U.S. patent application number 16/314564 was filed with the patent office on 2019-06-06 for method for transmitting and receiving data in wireless communication system and apparatus therefor.
The applicant listed for this patent is LG Electronics Inc.. Invention is credited to Hyukjin CHAE, Myoungseob KIM, Seungmin LEE, Hanbyul SEO.
Application Number | 20190174530 16/314564 |
Document ID | / |
Family ID | 60785467 |
Filed Date | 2019-06-06 |
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United States Patent
Application |
20190174530 |
Kind Code |
A1 |
KIM; Myoungseob ; et
al. |
June 6, 2019 |
METHOD FOR TRANSMITTING AND RECEIVING DATA IN WIRELESS
COMMUNICATION SYSTEM AND APPARATUS THEREFOR
Abstract
The present disclosure proposes a method for transmitting and
receiving data through sidelink in a wireless communication system
supporting Vehicle-to-Everything (V2X) communication. Particularly,
the method performed by a first User Equipment includes receiving,
from a base station, Downlink Control Information (DCI) including
information related to a transmission of first control information;
transmitting, to the second User Equipment, the first control
information based on the received DCI; and transmitting, to the
second User Equipment, one or more data through the sidelink.
Inventors: |
KIM; Myoungseob; (Seoul,
KR) ; SEO; Hanbyul; (Seoul, KR) ; LEE;
Seungmin; (Seoul, KR) ; CHAE; Hyukjin; (Seoul,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG Electronics Inc. |
Seoul |
|
KR |
|
|
Family ID: |
60785467 |
Appl. No.: |
16/314564 |
Filed: |
July 3, 2017 |
PCT Filed: |
July 3, 2017 |
PCT NO: |
PCT/KR2017/007049 |
371 Date: |
December 31, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62357393 |
Jul 1, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 1/0025 20130101;
H04W 4/40 20180201; H04L 5/0064 20130101; H04L 5/0078 20130101;
H04L 5/0053 20130101; H04W 72/042 20130101; H04W 76/14 20180201;
H04W 72/12 20130101; H04L 1/0009 20130101; H04L 1/0003 20130101;
H04W 72/1289 20130101; H04W 72/0446 20130101; H04W 72/1263
20130101 |
International
Class: |
H04W 72/12 20060101
H04W072/12; H04L 5/00 20060101 H04L005/00; H04W 72/04 20060101
H04W072/04; H04W 4/40 20060101 H04W004/40 |
Claims
1. A method for transmitting data through sidelink in a wireless
communication system supporting Vehicle-to-Everything (V2X)
communication, the method performed by a first User Equipment
comprising: receiving, from a base station, Downlink Control
Information (DCI) including information related to a transmission
of first control information, wherein the first control information
is used for scheduling data transmitted to a second User Equipment;
transmitting, to the second User Equipment, the first control
information based on the received DCI; and transmitting, to the
second User Equipment, one or more data through the sidelink,
wherein the DCI is transmitted in subframe #n, wherein the first
control information is transmitted in subframe #n+k or in a
specific sidelink subframe generated after the subframe #n+k, and
wherein the DCI includes second control information indicating a
timing gap between a first data transmission and a second data
transmission and wherein the second control information is a timing
gap field.
2. The method of claim 1, wherein the k is 4.
3. The method of claim 1, wherein the first control information and
the one or more data are transmitted to the second User Equipment
on an identical timing.
4. The method of claim 3, wherein the identical timing is an
identical subframe.
5. The method of claim 1, wherein the first data transmission is an
initial transmission of data, and wherein the second data
transmission is a retransmission of data.
6. The method of claim 1, wherein the first control information is
a Scheduling Assignment (SA).
7. (canceled)
8. The method of claim 1, wherein the first control information
includes the second control information.
9. The method of claim 1, wherein the specific sidelink subframe
includes initial sidelink subframes generated after the subframe
#n+k.
10. The method of claim 1, when resource allocations for the one or
more data are scheduled simultaneously by Dynamic Scheduling and
Semi-Persistent Scheduling (SPS), wherein either one of the Dynamic
Scheduling and the SPS is applied based on a specific
criterion.
11. The method of claim 10, wherein the specific criterion includes
at least one of a length of transmission period of the SPS or an
importance of transmission data.
12. A first User Equipment for transmitting data through sidelink
in a wireless communication system supporting Vehicle-to-Everything
(V2X) communication, the first User Equipment comprising: a Radio
Frequency (RF) unit configured to transmit and receive a radio
signal; and a processor functionally connected with the RF unit,
wherein the processor is configured to perform: receiving, from a
base station, Downlink Control Information (DCI) including
information related to a transmission of first control information,
wherein the first control information is used for scheduling data
transmitted to a second User Equipment; transmitting, to the second
User Equipment, the first control information based on the received
DCI; and transmitting, to the second User Equipment, one or more
data through the sidelink, wherein the DCI is transmitted in
subframe #n, wherein the first control information is transmitted
in subframe #n+k or in a specific sidelink subframe generated after
the subframe #n+k, wherein the DCI includes second control
information indicating a timing gap between a first data
transmission and a second data transmission, and wherein the second
control information is a timing gap field.
13. The first User Equipment of claim 12, wherein the k is 4.
14. The first User Equipment of claim 12, wherein the first control
information and the one or more data are transmitted to the second
User Equipment on an identical timing.
15. The first User Equipment of claim 14, wherein the identical
timing is an identical subframe.
16. The first User Equipment of claim 12, wherein the first data
transmission is an initial transmission of data, and wherein the
second data transmission is a retransmission of data.
17. (canceled)
18. The first User Equipment of claim 12, wherein the first control
information includes the second control information.
19. The first User Equipment of claim 12, wherein the specific
sidelink subframe includes initial sidelink subframes generated
after the subframe #n+k.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is the National Stage filing under 35
U.S.C. 371 of International Application No. PCT/KR2017/007049,
filed on Jul. 3, 2017, which claims the benefit of U.S. Provisional
Application No. 62/357,393 filed on Jul. 1, 2016, the contents of
which are all hereby incorporated by reference herein in their
entirety.
TECHNICAL FIELD
[0002] The present invention relates to a wireless communication
system, and more particularly, to a method for transmitting and
receiving data between User Equipments in a wireless communication
system that supports Vehicle-to-Everything (V2X) communication and
an apparatus supporting the same.
BACKGROUND ART
[0003] Mobile communication systems have been generally developed
to provide voice services while guaranteeing user mobility. Such
mobile communication systems have gradually expanded their coverage
from voice services through data services up to high-speed data
services. However, as current mobile communication systems suffer
resource shortages and users demand even higher-speed services,
development of more advanced mobile communication systems is
needed.
[0004] The requirements of the next-generation mobile communication
system may include supporting huge data traffic, a remarkable
increase in the transfer rate of each user, the accommodation of a
significantly increased number of connection devices, very low
end-to-end latency, and high energy efficiency. To this end,
various techniques, such as small cell enhancement, dual
connectivity, massive multiple input multiple output (MIMO),
in-band full duplex, non-orthogonal multiple access (NOMA),
supporting super-wide band, and device networking, have been
researched.
DISCLOSURE
Technical Problem
[0005] An object of the present disclosure is to provide a method
for transmitting and receiving data through Sidelink between User
Equipments in a wireless communication system that supports
Vehicle-to-Everything (V2X) communication.
[0006] Particularly, an object of the present disclosure is to
provide a method for determining data transmission timing based on
Scheduling Assignment (SA) transmission timing in V2X
communication.
[0007] In addition, an object of the present disclosure is to
provide a method for determining data transmission timing based on
DCI transmission timing in V2X communication.
[0008] In addition, an object of the present disclosure is to
define a new field for determining transmission timing between data
in V2X communication.
[0009] In addition, an object of the present disclosure is to apply
either one of scheduling considering a priority when dynamic
scheduling and Semi-Persistent Scheduling (SPS) are scheduled
simultaneously in relation to a data transmission in V2X
communication.
[0010] Technical objects to be achieved by the present invention
are not limited to the aforementioned technical objects, and other
technical objects not described above may be evidently understood
by a person having ordinary skill in the art to which the present
invention pertains from the following description.
Technical Solution
[0011] A method for transmitting data through sidelink in a
wireless communication system supporting Vehicle-to-Everything
(V2X) communication according to the present disclosure includes
receiving, from a base station, Downlink Control Information (DCI)
including information related to a transmission of first control
information, the first control information is used for scheduling
data transmitted to a second User Equipment; transmitting, to the
second User Equipment, the first control information based on the
received DCI; and transmitting, to the second User Equipment, one
or more data through the sidelink, the DCI is transmitted in
subframe #n, the first control information is transmitted in
subframe #n+k or in a specific sidelink subframe generated after
the subframe #n+k, and the DCI includes second control information
indicating a timing gap between a first data transmission and a
second data transmission.
[0012] In addition, in the present disclosure, the k is 4.
[0013] In addition, in the present disclosure, the first control
information and the one or more data are transmitted to the second
User Equipment on an identical timing.
[0014] In addition, in the present disclosure, the identical timing
is an identical subframe.
[0015] In addition, in the present disclosure, the first data
transmission is an initial transmission of data, and the second
data transmission is a retransmission of data.
[0016] In addition, in the present disclosure, the first control
information is a Scheduling Assignment (SA).
[0017] In addition, in the present disclosure, the second control
information is a timing gap field.
[0018] In addition, in the present disclosure, the first control
information includes the second control information.
[0019] In addition, in the present disclosure, the specific
sidelink subframe includes initial sidelink subframes generated
after the subframe #n+k.
[0020] In addition, in the present disclosure, when resource
allocations for the one or more data are scheduled simultaneously
by Dynamic Scheduling and Semi-Persistent Scheduling (SPS), either
one of the Dynamic Scheduling and the SPS is applied based on a
specific criterion.
[0021] In addition, in the present disclosure, the specific
criterion includes at least one of a length of transmission period
of the SPS or an importance of transmission data.
[0022] A first User Equipment for transmitting data through
sidelink in a wireless communication system supporting
Vehicle-to-Everything (V2X) communication according to the present
disclosure includes a Radio Frequency (RF) unit configured to
transmit and receive a radio signal; and a processor functionally
connected with the RF unit, wherein the processor is configured to
perform: receiving, from a base station, Downlink Control
Information (DCI) including information related to a transmission
of first control information, the first control information is used
for scheduling data transmitted to a second User Equipment;
transmitting, to the second User Equipment, the first control
information based on the received DCI; and transmitting, to the
second User Equipment, one or more data through the sidelink, the
DCI is transmitted in subframe #n, the first control information is
transmitted in subframe #n+k or in a specific sidelink subframe
generated after the subframe #n+k, and the DCI includes second
control information indicating a timing gap between a first data
transmission and a second data transmission.
Technical Effects
[0023] According to an embodiment of the present invention, a
timing on which a data transmission is started is clearly defined
based on SA transmission timing or DCI transmission timing, and a
problem of unable to transmit data when failing to receive
information for a data transmission timing from a base station.
[0024] In addition, according to an embodiment of the present
invention, Time-Resource Pattern for Transmission (T-RPT) pattern
which is previously used in relation to a data transmission in
Vehicle-to-Everything (V2X) communication is not used, but an
indicator indicating spacing between data transmissions is used,
and there is an effect of reducing a size of DCI.
[0025] Effects which may be obtained by the present invention are
not limited to the aforementioned effects, and other technical
effects not described above may be evidently understood by a person
having ordinary skill in the art to which the present invention
pertains from the following description.
DESCRIPTION OF DRAWINGS
[0026] The accompanying drawings, which are included to provide a
further understanding of the present invention and are incorporated
in and constitute a part of this application, illustrate
embodiments of the present invention together with the detailed
description serving to describe the principle of the present
invention.
[0027] FIG. 1 illustrates a radio frame structure in a wireless
communication system to which the present invention may be
applied.
[0028] FIG. 2 is a diagram illustrating a resource grid for one
downlink slot in a wireless communication system to which the
present invention may be applied.
[0029] FIG. 3 illustrates a downlink subframe structure in a
wireless communication system to which the present invention may be
applied.
[0030] FIG. 4 illustrates an uplink subframe structure in a
wireless communication system to which the present invention may be
applied.
[0031] FIG. 5 is a diagram for schematically describing D2D
communication in a wireless communication system to which the
present invention may be applied.
[0032] FIG. 6 illustrates various scenarios of D2D communication in
a wireless communication system to which the method proposed in the
present disclosure may be applied.
[0033] FIG. 7 illustrates protocol stack for Sidelink
communication.
[0034] FIG. 8 illustrates control plane protocol stack for
one-to-one Sidelink communication to which the present invention
may be applied.
[0035] FIG. 9 is a diagram for describing distributed discovery
resource allocation scheme in a wireless communication system
supporting Sidelink.
[0036] FIG. 10 illustrates Sidelink operation procedure in Sidelink
communication Mode 1 by a control of an eNB and a method for
performing Sidelink communication by transmitting and receiving the
related information.
[0037] FIG. 11 illustrates a method for transmitting downlink
control information for Sidelink communication between UEs in a
wireless communication system supporting Sidelink.
[0038] FIG. 12 illustrates a type of V2X application to which the
present invention may be applied.
[0039] FIG. 13 illustrates broadcast based V2V communication to
which the present invention may be applied.
[0040] FIG. 14 illustrates examples of V2X operation mode based on
only PC5 interface.
[0041] FIG. 15 illustrates examples of V2X operation mode based on
only Uu interface.
[0042] FIG. 16 illustrates examples of V2X operation mode based on
both of Uu interface and PC5 interface.
[0043] FIG. 17 illustrates examples of scheduling scheme applicable
to V2V Sidelink communication.
[0044] FIG. 18 illustrates an example of SA transmission
scheme.
[0045] FIG. 19 illustrates an operation flowchart for a first UE to
transmit and receive data in a wireless communication system
supporting Vehicle-to-Everything (V2X).
[0046] FIG. 20 illustrates a method for determining a transmission
timing of data using T-RPT pattern proposed in the present
disclosure.
[0047] FIG. 21 illustrates another method for determining a
transmission timing of data using T-RPT pattern proposed in the
present disclosure.
[0048] FIG. 22 illustrates another method for determining a
transmission timing of data using T-RPT pattern proposed in the
present disclosure.
[0049] FIG. 23 is a flowchart illustrating an example of a method
for transmitting and receiving data in V2X Sidelink communication
proposed in the present disclosure.
[0050] FIG. 24 illustrates a block diagram of a wireless
communication device to which the methods proposed in the present
disclosure may be applied.
[0051] FIG. 25 illustrates a block diagram of a wireless
communication apparatus according to an embodiment of the present
invention.
BEST MODE FOR INVENTION
[0052] Hereinafter, preferred embodiments of the present invention
will be described in detail with reference to the accompanying
drawings. A detailed description to be disclosed below together
with the accompanying drawing is to describe embodiments of the
present invention and not to describe a unique embodiment for
carrying out the present invention. The detailed description below
includes details in order to provide a complete understanding.
However, those skilled in the art know that the present invention
can be carried out without the details.
[0053] In some cases, in order to prevent a concept of the present
invention from being ambiguous, known structures and devices may be
omitted or may be illustrated in a block diagram format based on
core function of each structure and device.
[0054] In the specification, a base station means a terminal node
of a network directly performing communication with a terminal. In
the present document, specific operations described to be performed
by the base station may be performed by an upper node of the base
station in some cases. That is, it is apparent that in the network
constituted by multiple network nodes including the base station,
various operations performed for communication with the terminal
may be performed by the base station or other network nodes other
than the base station. A base station (BS) may be generally
substituted with terms such as a fixed station, Node B,
evolved-NodeB (eNB), a base transceiver system (BTS), an access
point (AP), and the like. Further, a `terminal` may be fixed or
movable and be substituted with terms such as user equipment (UE),
a mobile station (MS), a user terminal (UT), a mobile subscriber
station (MSS), a subscriber station (SS), an advanced mobile
station (AMS), a wireless terminal (WT), a Machine-Type
Communication (MTC) device, a Machine-to-Machine (M2M) device, a
Device-to-Device (D2D) device, and the like.
[0055] Hereinafter, a downlink means communication from the base
station to the terminal and an uplink means communication from the
terminal to the base station. In the downlink, a transmitter may be
a part of the base station and a receiver may be a part of the
terminal. In the uplink, the transmitter may be a part of the
terminal and the receiver may be a part of the base station.
[0056] Specific terms used in the following description are
provided to help appreciating the present invention and the use of
the specific terms may be modified into other forms within the
scope without departing from the technical spirit of the present
invention.
[0057] The following technology may be used in various wireless
access systems, such as code division multiple access (CDMA),
frequency division multiple access (FDMA), time division multiple
access (TDMA), orthogonal frequency division multiple access
(OFDMA), single carrier-FDMA (SC-FDMA), non-orthogonal multiple
access (NOMA), and the like. The CDMA may be implemented by radio
technology universal terrestrial radio access (UTRA) or CDMA2000.
The TDMA may be implemented by radio technology such as global
system for mobile communications (GSM)/general packet radio service
(GPRS)/enhanced data rates for GSM Evolution (EDGE). The OFDMA may
be implemented as radio technology such as IEEE 802.11(Wi-Fi), IEEE
802.16 (WiMAX), IEEE 802-20, E-UTRA (Evolved UTRA), and the like.
The UTRA is a part of a universal mobile telecommunication system
(UMTS). 3rd generation partnership project (3GPP) long term
evolution (LTE) as a part of an evolved UMTS (E-UMTS) using
evolved-UMTS terrestrial radio access (E-UTRA) adopts the OFDMA in
a downlink and the SC-FDMA in an uplink. LTE-advanced (A) is an
evolution of the 3GPP LTE.
[0058] The embodiments of the present invention may be based on
standard documents disclosed in at least one of IEEE 802, 3GPP, and
3GPP2 which are the wireless access systems. That is, steps or
parts which are not described to definitely show the technical
spirit of the present invention among the embodiments of the
present invention may be based on the documents. Further, all terms
disclosed in the document may be described by the standard
document.
[0059] 3GPP LTE/LTE-A is primarily described for clear description,
but technical features of the present invention are not limited
thereto.
[0060] (Terminology and Definition)
[0061] Carrier frequency: Center frequency of the cell
[0062] Cell: Combination of downlink and optionally uplink
resources. The linking between the carrier frequency of the
downlink resources and the carrier frequency of the uplink
resources is indicated in the system information transmitted on the
downlink resources.
[0063] Frequency layer: Set of cells with the same carrier
frequency
[0064] Sidelink: UE to UE interface for Sidelink communication, V2X
Sidelink communication and Sidelink discovery
[0065] Sidelink Control period, SC period: Period over which
resources are allocated in a cell for Sidelink control information
and Sidelink data transmissions
[0066] Sidelink communication: AS functionality enabling ProSe
Direct Communication between two or more nearby UEs, using E-UTRA
technology but not traversing any network node
[0067] Sidelink discovery: AS functionality enabling ProSe Direct
Discovery using E-UTRA technology but not traversing any network
node
[0068] Timing Advance Group, TAG: A group of serving cells that is
configured by RRC and that, for the cells with an UL configured,
use the same timing reference cell and the same Timing Advance
value
[0069] V2X Sidelink communication: AS functionality enabling V2X
Communication between nearby UEs, using E-UTRA technology but not
traversing any network node
[0070] The following acronyms are applied for an object of the
present invention.
[0071] ACK Acknowledgement
[0072] ARQ Automatic Repeat Request
[0073] CC Component Carrier
[0074] C-RNTI Cell RNTI
[0075] DCCH Dedicated Control Channel
[0076] DL Downlink
[0077] DwPTS Downlink Pilot Time Slot
[0078] eNB E-UTRAN NodeB
[0079] EPC Evolved Packet Core
[0080] EPS Evolved Packet System
[0081] E-RAB E-UTRAN Radio Access Bearer
[0082] E-UTRA Evolved UTRA
[0083] E-UTRAN Evolved UTRAN
[0084] FDD Frequency Division Duplex
[0085] FDM Frequency Division Multiplexing
[0086] LTE Long Term Evolution
[0087] MAC Medium Access Control
[0088] MCS Modulation and Coding Scheme
[0089] OFDM Orthogonal Frequency Division Multiplexing
[0090] OFDMA Orthogonal Frequency Division Multiple Access
[0091] ProSe Proximity based Services
[0092] PSBCH Physical Sidelink Broadcast CHannel
[0093] PSCCHPhysical Sidelink Control CHannel
[0094] PSDCHPhysical Sidelink Discovery CHannel
[0095] PSK Pre-Shared Key
[0096] PSSCH Physical Sidelink Shared CHannel
[0097] PUCCH Physical Uplink Control CHannel
[0098] PUSCHPhysical Uplink Shared CHannel
[0099] QoS Quality of Service
[0100] RRC Radio Resource Control
[0101] SI System Information
[0102] SIB System Information Block
[0103] SL-BCH Sidelink Broadcast Channel
[0104] SL-DCH Sidelink Discovery Channel
[0105] SL-RNTI Sidelink RNTI
[0106] SL-SCH Sidelink Shared Channel
[0107] STCH Sidelink Traffic Channel
[0108] TB Transport Block
[0109] TDD Time Division Duplex
[0110] TDM Time Division Multiplexing
[0111] TTI Transmission Time Interval
[0112] UE User Equipment
[0113] UL Uplink
[0114] UM Unacknowledged Mode
[0115] V2I Vehicle-to-Infrastructure
[0116] V2N Vehicle-to-Network
[0117] V2P Vehicle-to-Pedestrian
[0118] V2V Vehicle-to-Vehicle
[0119] V2X Vehicle-to-Everything
[0120] General System
[0121] FIG. 1 illustrates a structure a radio frame in a wireless
communication system to which the present invention can be
applied.
[0122] In 3GPP LTE/LTE-A, radio frame structure type 1 may be
applied to frequency division duplex (FDD) and radio frame
structure type 2 may be applied to time division duplex (TDD) are
supported.
[0123] In FIG. 1, the size of the radio frame in the time domain is
represented by a multiple of a time unit of T_s=1/(15000*2048). The
downlink and uplink transmissions are composed of radio frames
having intervals of T_f=307200*T_s=10 ms.
[0124] FIG. 1(a) illustrates the type 1 radio frame structure. The
type 1 radio frame may be applied to both full duplex FDD and half
duplex FDD.
[0125] The radio frame includes 10 subframes. One radio frame
includes 20 slots each having a length of T_slot=15360*T_s=0.5 ms.
Indices 0 to 19 are assigned to the respective slots. One subframe
includes two contiguous slots in the time domain, and a subframe i
includes a slot 2i and a slot 2i+1. The time taken to send one
subframe is called a transmission time interval (TTI). For example,
the length of one subframe may be 1 ms, and the length of one slot
may be 0.5 ms.
[0126] In FDD, uplink transmission and downlink transmission are
classified in the frequency domain. There is no restriction to full
duplex FDD, whereas a UE is unable to perform transmission and
reception at the same time in a half duplex FDD operation.
[0127] One slot includes a plurality of orthogonal frequency
division multiplexing (OFDM) symbols in the time domain and
includes a plurality of resource blocks (RBs) in the frequency
domain. An OFDM symbol is for expressing one symbol period because
3GPP LTE uses OFDMA in downlink. The OFDM symbol may also be called
an SC-FDMA symbol or a symbol period. The resource block is a
resource allocation unit and includes a plurality of contiguous
subcarriers in one slot.
[0128] FIG. 1(b) illustrates the type 2 radio frame structure. The
type 2 radio frame structure includes 2 half frames each having a
length of 153600*T_s=5 ms. Each of the half frames includes 5
subframes each having a length of 30720*T_s=1 ms.
[0129] In the type 2 radio frame structure of a TDD system, an
uplink-downlink configuration is a rule showing how uplink and
downlink are allocated (or reserved) with respect to all of
subframes. Table 1 represents the uplink-downlink
configuration.
TABLE-US-00001 TABLE 1 Subframe number plink- ownlink-to-Uplink
Downlink Switch-point configuration periodicity ms ms ms 0ms 0ms
0ms ms indicates data missing or illegible when filed
[0130] Referring to Table 1, "D" indicates a subframe for downlink
transmission, "U" indicates a subframe for uplink transmission, and
"S" indicates a special subframe including the three fields of a
downlink pilot time slot (DwPTS), a guard period (GP), and an
uplink pilot time slot (UpPTS) for each of the subframes of the
radio frame.
[0131] The DwPTS is used for initial cell search, synchronization
or channel estimation by a UE. The UpPTS is used for an eNB to
perform channel estimation and for a UE to perform uplink
transmission synchronization. The GP is an interval for removing
interference occurring in uplink due to the multi-path delay of a
downlink signal between uplink and downlink.
[0132] Each subframe i includes the slot 2i and the slot 2i+1 each
having "T slot=15360*T_s=0.5 ms."
[0133] The uplink-downlink configuration may be divided into seven
types. The location and/or number of downlink subframes, special
subframes, and uplink subframes are different in the seven
types.
[0134] A point of time changed from downlink to uplink or a point
of time changed from uplink to downlink is called a switching
point. Switch-point periodicity means a cycle in which a form in
which an uplink subframe and a downlink subframe switch is repeated
in the same manner. The switch-point periodicity supports both 5 ms
and 10 ms. In the case of a cycle of the 5 ms downlink-uplink
switching point, the special subframe S is present in each half
frame. In the case of the cycle of the 5 ms downlink-uplink
switching point, the special subframe S is present only in the
first half frame.
[0135] In all of the seven configurations, No. 0 and No. 5
subframes and DwPTSs are an interval for only downlink
transmission. The UpPTSs, the subframes, and a subframe subsequent
to the subframes are always an interval for uplink
transmission.
[0136] Both an eNB and a UE may be aware of such uplink-downlink
configurations as system information. The eNB may notify the UE of
a change in the uplink-downlink allocation state of a radio frame
by sending only the index of configuration information whenever
uplink-downlink configuration information is changed. Furthermore,
the configuration information is a kind of downlink control
information. Like scheduling information, the configuration
information may be transmitted through a physical downlink control
channel (PDCCH) and may be transmitted to all of UEs within a cell
in common through a broadcast channel as broadcast information.
[0137] Table 2 represents a configuration (i.e., the length of a
DwPTS/GP/UpPTS) of the special subframe.
TABLE-US-00002 TABLE 2 Normal cyclic Extended cyclic prefix pecial
prefix in downlink in downlink subframe UpPT UpPTS configuration
wPTS S wPTS ormal xtended ormal xtended cyclic cyclic cyclic cyclic
prefix prefix prefix in prefix in in in uplink uplink uplink
uplink
[0138] The structure of the radio frame according to the example of
FIG. 1 is only one example. The number of subcarriers included in
one radio frame, the number of slots included in one subframe, and
the number of OFDM symbols included in one slot may be changed in
various manners.
[0139] FIG. 2 is a diagram illustrating a resource grid for one
downlink slot in the wireless communication system to which the
present invention can be applied.
[0140] Referring to FIG. 2, one downlink slot includes the
plurality of OFDM symbols in the time domain. Herein, it is
exemplarily described that one downlink slot includes 7 OFDM
symbols and one resource block includes 12 subcarriers in the
frequency domain, but the present invention is not limited
thereto.
[0141] Each element on the resource grid is referred to as a
resource element and one resource block includes 12.times.7
resource elements. The number of resource blocks included in the
downlink slot, NDL is subordinated to a downlink transmission
bandwidth.
[0142] A structure of the uplink slot may be the same as that of
the downlink slot.
[0143] FIG. 3 illustrates a structure of a downlink subframe in the
wireless communication system to which the present invention can be
applied.
[0144] Referring to FIG. 3, a maximum of three former OFDM symbols
in the first slot of the sub frame is a control region to which
control channels are allocated and residual OFDM symbols is a data
region to which a physical downlink shared channel (PDSCH) is
allocated. Examples of the downlink control channel used in the
3GPP LTE include a Physical Control Format Indicator Channel
(PCFICH), a Physical Downlink Control Channel (PDCCH), a Physical
Hybrid-ARQ Indicator Channel (PHICH), and the like.
[0145] The PFCICH is transmitted in the first OFDM symbol of the
subframe and transports information on the number (that is, the
size of the control region) of OFDM symbols used for transmitting
the control channels in the subframe. The PHICH which is a response
channel to the uplink transports an Acknowledgement
(ACK)/Not-Acknowledgement (NACK) signal for a hybrid automatic
repeat request (HARQ). Control information transmitted through a
PDCCH is referred to as downlink control information (DCI). The
downlink control information includes uplink resource allocation
information, downlink resource allocation information, or an uplink
transmission (Tx) power control command for a predetermined
terminal group.
[0146] The PDCCH may transport A resource allocation and
transmission format (also referred to as a downlink grant) of a
downlink shared channel (DL-SCH), resource allocation information
(also referred to as an uplink grant) of an uplink shared channel
(UL-SCH), paging information in a paging channel (PCH), system
information in the DL-SCH, resource allocation for an upper-layer
control message such as a random access response transmitted in the
PDSCH, an aggregate of transmission power control commands for
individual terminals in the predetermined terminal group, a voice
over IP (VoIP). A plurality of PDCCHs may be transmitted in the
control region and the terminal may monitor the plurality of
PDCCHs. The PDCCH is constituted by one or an aggregate of a
plurality of continuous control channel elements (CCEs). The CCE is
a logical allocation wise used to provide a coding rate depending
on a state of a radio channel to the PDCCH. The CCEs correspond to
a plurality of resource element groups. A format of the PDCCH and a
bit number of usable PDCCH are determined according to an
association between the number of CCEs and the coding rate provided
by the CCEs.
[0147] The base station determines the PDCCH format according to
the DCI to be transmitted and attaches the control information to a
cyclic redundancy check (CRC) to the control information. The CRC
is masked with a unique identifier (referred to as a radio network
temporary identifier (RNTI)) according to an owner or a purpose of
the PDCCH. In the case of a PDCCH for a specific terminal, the
unique identifier of the terminal, for example, a cell-RNTI
(C-RNTI) may be masked with the CRC. Alternatively, in the case of
a PDCCH for the paging message, a paging indication identifier, for
example, the CRC may be masked with a paging-RNTI (P-RNTI). In the
case of a PDCCH for the system information, in more detail, a
system information block (SIB), the CRC may be masked with a system
information identifier, that is, a system information (SI)-RNTI.
The CRC may be masked with a random access (RA)-RNTI in order to
indicate the random access response which is a response to
transmission of a random access preamble.
[0148] Enhanced PDCCH (EPDCCH) carries UE-specific signaling. The
EPDCCH is located in a physical resource block (PRB) that is set to
be terminal specific. In other words, as described above, the PDCCH
may be transmitted in up to three OFDM symbols in the first slot in
the subframe, but the EPDCCH may be transmitted in a resource
region other than the PDCCH. The time (i.e., symbol) at which the
EPDCCH in the subframe starts may be set in the UE through higher
layer signaling (e.g., RRC signaling, etc.).
[0149] The EPDCCH is a transport format, a resource allocation and
HARQ information associated with the DL-SCH and a transport format,
a resource allocation and HARQ information associated with the
UL-SCH, and resource allocation information associated with SL-SCH
(Sidelink Shared Channel) and PSCCH Information, and so on.
Multiple EPDCCHs may be supported and the terminal may monitor the
set of EPCCHs.
[0150] The EPDCCH may be transmitted using one or more successive
advanced CCEs (ECCEs), and the number of ECCEs per EPDCCH may be
determined for each EPDCCH format.
[0151] Each ECCE may be composed of a plurality of enhanced
resource element groups (EREGs). EREG is used to define the mapping
of ECCE to RE. There are 16 EREGs per PRB pair. All REs are
numbered from 0 to 15 in the order in which the frequency
increases, except for the RE that carries the DMRS in each PRB
pair.
[0152] The UE may monitor a plurality of EPDCCHs. For example, one
or two EPDCCH sets may be set in one PRB pair in which the terminal
monitors the EPDCCH transmission.
[0153] Different coding rates may be realized for the EPOCH by
merging different numbers of ECCEs. The EPOCH may use localized
transmission or distributed transmission, which may result in
different mapping of the ECCE to the REs in the PRB.
[0154] FIG. 4 illustrates a structure of an uplink subframe in the
wireless communication system to which the present invention can be
applied.
[0155] Referring to FIG. 4, the uplink subframe may be divided into
the control region and the data region in a frequency domain. A
physical uplink control channel (PUCCH) transporting uplink control
information is allocated to the control region. A physical uplink
shared channel (PUSCH) transporting user data is allocated to the
data region. One terminal does not simultaneously transmit the
PUCCH and the PUSCH in order to maintain a single carrier
characteristic.
[0156] A resource block (RB) pair in the subframe are allocated to
the PUCCH for one terminal. RBs included in the RB pair occupy
different subcarriers in two slots, respectively. The RB pair
allocated to the PUCCH is frequency-hopped in a slot boundary.
[0157] Device-to-Device (D2D) Communication
[0158] A device-to-device (D2D) communication or sidelink
technology refers to a method of directly communicating with each
other by geographically close UEs without the intervention of
infrastructure, such as a base station. In the D2D communication
technology, a technology chiefly using a non-licensed frequency
band, such as already commercialized Wi-Fi Direct and Bluetooth,
has been developed. However, for the purpose of improving frequency
use efficiency of the cellular system, a D2D communication
technology using a licensed frequency band has been developed and
standardization thereof is performed.
[0159] In general, D2D communication is limitedly used as a term to
refer to communication between things and thing intelligent
communication. However, D2D communication in the present invention
may include all types of communication between simple devices
having a communication function and various types of devices having
a communication function, such as smartphones or personal
computers.
[0160] D2D communication may also be called a sidelink or sidelink
transmission.
[0161] A sidelink includes sidelink discovery, sidelink
communication, and V2X sidelink communication between UEs.
[0162] FIG. 5 is a diagram for conceptually illustrating D2D
communication in a wireless communication system to which the
present invention may be applied.
[0163] FIG. 5(a) illustrates a communication method based on the
existing eNB. A UE 1 may transmit data to the eNB on uplink, and
the eNB may transmit data to a UE 2 on downlink. Such a
communication method may be called an indirect communication method
through an eNB. In the indirect communication method, an Xn link
(link between eNBs or link between an eNB and a relay and may be
called a backhaul link), that is, a link defined in the existing
wireless communication system and/or an Uu link (link between an
eNB and a UE or link between a relay and a UE, and may be called an
access link) may be related.
[0164] FIG. 5(b) illustrates a UE-to-UE communication method as an
example of D2D communication. A data exchange between UEs may be
performed without the intervention of an eNB. Such a communication
method may be called a direct communication method between devices.
The D2D direct communication method has advantages in that latency
is reduced compared to an indirect communication method through the
existing eNB and less radio resources are used.
[0165] FIG. 6 illustrates examples of various scenarios D2D
communication to which a method proposed in this specification may
be applied.
[0166] The scenario of D2D communication may be basically divided
into (1) Out-of-Coverage Network, (2) Partial-Coverage Network and
(3) In-Coverage Network depending on whether a UE 1 and a UE 2 are
located in-coverage/out-of-coverage.
[0167] In-Coverage Network may be divided into
In-Coverage-Single-Cell and In-Coverage-Multi-Cell based on the
number of cells corresponding to coverage of an eNB.
[0168] FIG. 6(a) illustrates an example of the Out-of-Coverage
Network scenario of D2D communication. The Out-of-Coverage Network
scenario means that D2D UEs perform D2D communication without
control of an eNB. From FIG. 6(a), it may be seen that only a UE 1
and a UE 2 are present and the UE 1 and the UE 2 perform direct
communication.
[0169] FIG. 6(b) illustrates an example of the Partial-Coverage
Network scenario of D2D communication. The Partial-Coverage Network
scenario means that a D2D UE in coverage of a network and a D2D UE
out of coverage of the network perform D2D communication. From FIG.
6(b), it may be seen that a UE 1 in coverage of a network and a UE
2 out of coverage of the network communicate with each other.
[0170] FIG. 6(c) illustrates an example of the
In-Coverage-Single-Cell scenario. FIG. 8(d) illustrates an example
of the In-Coverage-Multi-Cell scenario. The In-Coverage Network
scenario means that D2D UEs perform D2D communication through
control of an eNB in coverage of a network. In FIG. 6(c), a UE 1
and a UE 2 are located in the same network coverage (or cell) and
perform D2D communication under the control of an eNB.
[0171] In FIG. 6(d), a UE 1 and a UE 2 are located in coverage of
networks, but are located in coverage of different networks.
Furthermore, the UE 1 and the UE 2 perform D2D communication under
the control of eNBs managing respective network coverages.
[0172] Hereinafter, D2D communication or a sidelink are described
more specifically.
[0173] D2D communication may operate in the scenarios shown in FIG.
6. In general, D2D communication may operate in coverage of a
network and out of coverage of a network. A link used for direct
communication between UEs may be referred to as a sidelink,
directlink or D2D link, but is collectively called a sidelink, for
convenience of description.
[0174] Sidelink transmission may operate in an uplink spectrum in
the case of FDD, and may operate in an uplink (or downlink)
subframe in the case of TDD. For the multiplexing sidelink
transmission and uplink transmission, time division multiplexing
(TDM) may be used.
[0175] Depending on the capability of a UE, sidelink transmission
and uplink transmission do not occur in a specific UE at the same
time. Sidelink transmission does not occur in an uplink subframe
used for uplink transmission or a sidelink subframe overlapping an
UpPTS partially or fully. Furthermore, sidelink transmission and
downlink transmission do not occur at the same time. Furthermore,
the transmission and reception of a sidelink do not occur at the
same time.
[0176] The structure of a physical resource used for sidelink
transmission may be the same as the structure of an uplink physical
resource. However, the last symbol of a sidelink subframe has a
guard period and is not used for sidelink transmission.
[0177] A sidelink subframe may have an extended CP or a normal
CP.
[0178] Sidelink communication may be basically divided into
sidelink discovery, sidelink communication, sidelink
synchronization, and vehicle-to-everything (V2X) sidelink
communication.
[0179] Sidelink communication is communication mode in which a UE
can perform direct communication through a PC5 interface. The
communication mode is supported when a UE is served by an E-UTRAN
and when a UE is out of coverage of E-UTRA.
[0180] Only UEs permitted to be used for a public safety operation
may perform sidelink communication.
[0181] In order to perform synchronization for an out-of-coverage
operation, a UE(s) may operate as a synchronization source by
transmitting a sidelink broadcast control channel (SBCCH) and a
synchronization signal.
[0182] An SBCCH delivers the most important system information
necessary to receive a different sidelink channel and a signal. The
SBCCH is transmitted in a fixed period of 40 ms along with a
synchronization signal. When a UE is in network coverage, the
contents of the SBCCH are derived or obtained from a parameter
signaled by an eNB.
[0183] When a UE is out of coverage, if the UE selects another UE
as a synchronization criterion, the contents of an SBCCH are
derived from a received SBCCH. If not, the UE uses a pre-configured
parameter. A system information block (SIB) 18 provides a
synchronization signal and resource information for SBCCH
transmission.
[0184] For an out-of-coverage operation, two pre-configured
subframes are present every 40 ms. A UE receives a synchronization
signal and SBCCH in one subframe. When the UE becomes a
synchronization source based on a defined criterion, it transmits a
synchronization signal and SBCCH in another subframe.
[0185] A UE performs sidelink communication on defined subframes
during a sidelink control period. The sidelink control period is
the period in which resources allocated to a cell occur for
sidelink control information and sidelink data transmission. The UE
transmits sidelink control information and sidelink data within the
sidelink control period.
[0186] The sidelink control information indicates a layer 1 ID and
transmission characteristics (e.g., MCS, the location of a resource
for a sidelink control period and timing alignment).
[0187] A UE performs transmission/reception through the Uu and PC5
in order of the following lower priority if a sidelink discovery
gap has not been configured. [0188] Uu transmission/reception
(highest priority); [0189] PC5 sidelink communication transmission
and reception; [0190] PC5 sidelink discovery
announcement/monitoring (lowest priority).
[0191] A UE performs transmission and reception through the Uu and
PC5 in order of the following lower priority if a sidelink
discovery gap has been configured: [0192] Uu transmission/reception
for RACH; [0193] PC5 sidelink discovery announcement during a
Sidelink Discovery Gap for transmission; [0194] Non-RACH Uu
transmission; [0195] PC5 sidelink discovery monitoring during a
Sidelink Discovery Gap for reception; [0196] Non-RACH Uu reception;
[0197] PC5 sidelink communication transmission and reception.
[0198] Sidelink Radio Protocol Structure
[0199] A UE radio protocol structure for sidelink communication
with respect to a user plane and a control plane is described.
[0200] FIG. 7 illustrates a protocol stack for sidelink
communication.
[0201] Specifically, FIG. 7(a) illustrates a protocol stack for a
user plane in which a PDCP, RLC and MAC sublayer (end in another
UE) perform functions on a user plane. The access layer protocol
stack of a PC5 interface includes a PDCP, RLC, MAC and PHY as shown
in FIG. 7(a).
[0202] User plane detailed information of sidelink communication:
[0203] There is no HARQ feedback for sidelink communication. [0204]
RLC UM is used for sidelink communication. [0205] A receiver UE
needs to maintain at least one RLC UM entity every transmission
peer UE. [0206] A reception RLC UM entity used for sidelink
communication does not need to be configured prior to the reception
of a first RLC UMD PDU. [0207] ROHC unidirectional mode is used for
the header compression of a PDCP for additional communication.
[0208] A UE may configure a plurality of logical channels. An LCID
included in a MAC subheader uniquely identifies a logical channel
within the range of one Source Layer-2 ID and Destination Layer-2
ID combination. A parameter for logical channel priority is not
configured.
[0209] An access layer (AS) is provided along with a ProSe
Per-Packet Priority (PPPP) of a protocol data unit transmitted
through the PC5 interface in a higher layer. There is a PPPP
related to each logical channel.
[0210] A UE configures and does not maintain a logical connection
to receiver UEs prior to one-to-multiple sidelink communication. A
higher layer configures and maintains a logical connection for
one-to-one sidelink communication, including a ProSe UE-to-Network
Relay task.
[0211] FIG. 7(b) illustrates a control plane protocol stack for an
SBCCH to which the present invention may be applied. In the PC5
interface, an access layer protocol stack for an SBCCH includes
RRC, RLC, MAC and PHY as in FIG. 7(b).
[0212] A control plane for configuring, maintaining and releasing a
logical connection for one-to-one sidelink communication is shown
in FIG. 8.
[0213] FIG. 8 illustrates a control plane protocol stack for
one-to-one sidelink communication to which the present invention
may be applied.
[0214] Sidelink Discovery
[0215] In sidelink communication, since a plurality of
transmitter/receiver UEs is distributed at a given location, a
sidelink discovery procedure for confirming the presence of
surrounding UEs is necessary before a specific UE perform sidelink
communication with surrounding UEs. Furthermore, sidelink discovery
may be used to confirm the presence of surrounding UEs and used for
various commercial purposes, such as advertising, issuing coupons
and finding friends, with respect to UEs within a proximity
area.
[0216] Sidelink discovery may be applied within network coverage
(including inter-cell, intra-cell). In inter-cell discovery, both
synchronous and asynchronous cell deployments may be taken into
consideration.
[0217] In this case, a signal (or message) periodically transmitted
by UEs for sidelink discovery may be referred to as a discovery
message, discovery signal, a beacon, etc. Hereinafter, a signal
periodically transmitted by UEs for sidelink discovery is
collectively called a discovery message, for convenience of
description.
[0218] If a UE 1 has the role of discovery message transmission,
the UE 1 transmits a discovery message, and a UE 2 receives the
discovery message. The transmission and reception roles of the UE 1
and the UE 2 may be changed. Transmission from the UE 1 may be
received by one or more UE(s), such as the UE 2.
[0219] A discovery message may include a single MAC PDU. In this
case, the single MAC PDU may include a UE ID and an application
ID.
[0220] A physical sidelink discovery channel (PSDCH) may be defined
as a channel in which a discovery message is transmitted. The
structure of a PSDCH channel may reuse a PUSCH structure.
[0221] Two types (sidelink discovery type 1 and sidelink discovery
type 2B) may be used as a resource allocation method for sidelink
discovery.
[0222] In the case of the sidelink discovery type 1, an eNB may
allocate a resource for discovery message transmission in a
non-UE-specific manner.
[0223] Specifically, a radio resource pool (i.e., discovery pool)
for discovery transmission and reception, including a plurality of
subframe sets and a plurality of resource block sets, is allocated
within a specific period (hereinafter "discovery period"). A
discovery transmitter UE randomly selects a specific resource
within the radio resource pool and then transmits a discovery
message.
[0224] Such a periodical discovery resource pool may be allocated
for discovery signal transmission in a semi-static manner.
Configuration information of a discovery resource pool for
discovery transmission includes a discovery period, a subframe set
which may be used for the transmission of a discovery signal within
a discovery period, and resource block set information.
[0225] Such configuration information of a discovery resource pool
may be transmitted to a UE by higher layer signaling. In the case
of an in-coverage UE, a discovery resource pool for discovery
transmission is configured by an eNB, and a UE may be notified of
the discovery resource pool through RRC signaling (e.g., a system
information block (SIB)).
[0226] A discovery resource pool allocated for discovery within one
discovery period may be multiplexed with a time-frequency resource
block having the same size through TDM and/or FDM. A time-frequency
resource block having the same size may be referred to as a
"discovery resource." A discovery resource may be divided as one
subframe unit, and may include two physical resource blocks (PRBs)
per slot in each subframe. One discovery resource may be used for
the transmission of a discovery MAC PDU by one UE.
[0227] Furthermore, a UE may repeatedly transmit a discovery signal
within a discovery period for the transmission of one transport
block. The transmission of a MAC PDU transmitted by one UE may be
repeated (e.g., repeated four times) contiguously or
non-contiguously within a discovery period (i.e., radio resource
pool). The number of transmissions of a discovery signal for one
transport block may be transmitted by a UE through higher layer
signaling.
[0228] A UE randomly selects the first discovery resource in a
discovery resource set which may be used for the repeated
transmission of a MAC PDU. Other discovery resources may be
determined in relation to the first discovery resource. For
example, a specific pattern may be pre-configured, and a next
discovery resource may be determined according to a pre-configured
pattern based on the location of a discovery resource first
selected by a UE. Furthermore, the UE may randomly select each
discovery resource within a discovery resource set which may be
used for the repeated transmission of a MAC PDU.
[0229] In the sidelink discovery type 2, a resource for discovery
message transmission is allocated in a UE-specific manner. Type 2
is subdivided into Type 2A and Type 2B. Type 2A is a method in
which an eNB allocates a resource at each transmission instance of
a discovery message by a UE within a discovery period. Type 2B is a
method of allocating a resource in a semi-persistent manner.
[0230] In the case of the sidelink discovery type 2B, a
RRC_CONNECTED UE requests the allocation of a resource for the
transmission of a sidelink discovery message from an eNB through
RRC signaling. Furthermore, the eNB may allocate the resource
through RRC signaling. When the UE makes transition to an RRC_IDLE
state or the eNB withdraws resource allocation through RRC
signaling, the UE releases the most recently allocated transmission
resource. As described above, in the case of the sidelink discovery
type 2B, a radio resource may be allocated by RRC signaling, and
the activation/deactivation of radio resources allocated by a PDCCH
may be determined.
[0231] A radio resource pool for discovery message reception is
configured by an eNB, and a UE may be notified of the radio
resource pool using RRC signaling (e.g., a system information block
(SIB)).
[0232] A discovery message receiver UE monitors both the discovery
resource pools of the sidelink discovery type 1 and type 2 for
discovery message reception.
[0233] A sidelink discovery method may be divided into a
centralized discovery method assisted by a central node, such as an
eNB, and a distributed discovery method for a UE autonomously to
confirm the presence of a surrounding UE without the help of a
central node.
[0234] In this case, in the case of the distributed discovery
method, a dedicated resource may be periodically allocated
separately from a cellular resource as a resource for a UE to
transmit and receive discovery messages.
[0235] FIG. 9 is a diagram for illustrating a distributed discovery
resource allocation method in a wireless communication system
supporting a sidelink.
[0236] Referring to FIG. 9, in the distributed discovery method, a
discovery subframe (i.e., "discovery resource pool") 901 for
discovery among all cellular uplink frequency-time resources is
fixedly (or dedicatedly) allocated, and the remaining region may
include the existing LTE uplink wide area network (WAN) subframe
region 902. The discovery resource pool may include one or more
subframes.
[0237] The discovery resource pool may be periodically allocated at
a specific time interval (i.e., "discovery period" or "PSDCH
period"). Furthermore, the discovery resource pool may be
repeatedly configured within one discovery period.
[0238] FIG. 9 illustrates an example in which a discovery resource
pool is allocated with a discovery period of 10 sec and 64
contiguous subframes are allocated in each discovery resource pool.
However, the sizes of a discovery period and time/frequency
resource of a discovery resource pool correspond to example, and
the present invention is not limited thereto.
[0239] A UE autonomously selects a resource (i.e., "discovery
resource") for transmitting its own discovery message within a
dedicatedly allocated discovery pool, and transmits a discovery
message through the selected resource.
[0240] Sidelink Communication
[0241] The application area of sidelink communication also includes
network edge-of-coverage in addition to in and out of network
coverage (in-coverage, out-of-coverage). Sidelink communication may
be used for purposes, such as public safety (PS).
[0242] If a UE 1 has the role of direct communication data
transmission, the
[0243] UE 1 transmits direct communication data, and a UE 2
receives direct communication data. The transmission and reception
roles of the UE 1 and the UE 2 may be changed. Direct communication
transmission from the UE 1 may be received by one or more UE(s),
such as the UE 2.
[0244] Sidelink discovery and sidelink communication are not
associated, but may be independently defined. That is, in groupcast
and broadcast direct communication, sidelink discovery is not
necessary. As described above, if sidelink discovery and sidelink
direct communication are independently defined, UEs do not need to
recognize an adjacent UE. In other words, in the case of groupcast
and broadcast direct communication, all receiver UEs within a group
do not need to be adjacent to each other.
[0245] A physical sidelink shared channel (PSSCH) may be defined as
a channel in which sidelink communication data is transmitted.
Furthermore, a physical sidelink control channel (PSCCH) may be
defined as a channel in which control information for sidelink
communication (e.g., scheduling assignment (SA) for sidelink
communication data transmission, transmission format) is
transmitted. A PSSCH and a PSCCH may reuse a PUSCH structure.
[0246] Two modes (Mode 1, Mode 2) may be used as a resource
allocation method for sidelink communication.
[0247] Mode 1 refers to a method of an eNB to schedule resources,
used to transmit data or control information for sidelink
communication, with respect to a UE. In in-coverage, Mode 1 is
applied.
[0248] An eNB configures a resource pool for sidelink
communication. The eNB may deliver information on a resource pool
for sidelink communication to the UE through higher layer
signaling. In this case, the resource pool for sidelink
communication may be divided into a control information pool (i.e.,
resource pool for transmitting a PSCCH) and a sidelink data pool
(i.e., resource pool for transmitting a PSSCH).
[0249] When a transmitter UE requests a resource for transmitting
control information and/or data from an eNB, the eNB schedules a
control information and sidelink data transmission resource within
a pool configured in the transmitter D2D UE using a PDCCH or
ePDCCH. Accordingly, the transmitter UE transmits control
information and sidelink data to a receiver UE using the scheduled
(i.e., allocated) resource.
[0250] Specifically, the eNB may perform scheduling on a resource
for transmitting control information (i.e., resource for
transmitting a PSCCH) using a downlink control information (DCI)
format 5 or a DCI format 5A, and may perform scheduling on a
resource for transmitting sidelink data (i.e., resource for
transmitting a PSSCH) using a sidelink control information (SCI)
format 0 or an SCI format 1. In this case, the DCI format 5
includes some fields of the SCI format 0, and the DCI format 5A
includes some fields of the SCI format 1.
[0251] In accordance with the above description, in the case of
Mode 1, a transmitter UE needs to be in the RRC_CONNECTED state in
order to perform sidelink communication. The transmitter UE
transmits a scheduling request to an eNB. A buffer status report
(BSR) procedure is performed so that an eNB can determine the
amount of resources requested by the transmitter UE.
[0252] When receiver UEs monitor a control information pool and
decode control information related thereto, they may selectively
decode sidelink data transmission related to the corresponding
control information. The receiver UE may not decode a sidelink data
pool based on a result of the decoding of control information.
[0253] A detailed example and signaling procedure of the sidelink
communication mode 1 are shown in FIGS. 10 and 11. In this case, as
described above, control information related to sidelink
communication is transmitted through a PSCCH, and data information
related to sidelink communication is transmitted through a
PSSCH.
[0254] FIG. 10 illustrates a method of performing a sidelink
operational procedure in a sidelink communication mode 1 based on
control of an eNB and sidelink communication by transmitting and
receiving related information.
[0255] As shown in FIG. 10, a PSCCH resource pool 1010 and/or a
PSSCH resource pool 1020 related to sidelink communication may be
pre-configured. The pre-configured resource pool may be transmitted
from an eNB to sidelink UEs through higher layer signaling (e.g.,
RRC signaling). In this case, the PSCCH resource pool and/or the
PSSCH resource pool may mean a resource (i.e., dedicated resource)
reserved for sidelink communication. In this case, the PSCCH is
control information for scheduling the transmission of sidelink
data (i.e., PSSCH), and may mean a channel in which the SCI format
0 is transmitted.
[0256] Furthermore, the PSCCH is transmitted according to a PSCCH
period, and the PSSCH is transmitted according to a PSSCH period.
The scheduling of the PSCCH is performed through the DCI format 5
(or DCI format 5A), and the scheduling of the PSSCH is performed
through the SCI format 0 (or SCI format 1). The DCI format 5 may be
referred to as a sidelink grant, and may be transmitted through a
physical layer channel or MAC layer channel, such as a PDCCH or an
EPDCCH.
[0257] In this case, the DCI format 5 includes resource information
for a PSCCH (i.e., resource allocation information), a transmission
power control (TPC) command for a PSCCH and PSSCH, a zero padding
(ZP) bit(s) and some fields of the SCI format 0 (e.g., frequency
hopping flag, resource block assignment and hopping resource
allocation information, a time resource pattern (e.g., subframe
pattern)).
[0258] Furthermore, the fields of the SCI format 0 is information
related to the scheduling of a PSSCH, and includes fields, such as
a frequency hopping flag, a time resource pattern, a modulation and
coding scheme (MCS), a TA indication, and a group destination
ID.
[0259] FIG. 11 illustrates a downlink control information
transmission method for sidelink communication between UEs in a
wireless communication system supporting sidelink communication.
FIG. 11 is merely for convenience of description and does not limit
the scope of the present invention.
[0260] Referring to FIG. 11, it is assumed that the DCI format 5 is
used as a sidelink grant. If the DCI format 5A is used, in FIG. 11,
the DCI format 5 is substituted with a DCI format 5A and the SCI
format 0 may be substituted with the SCI format 1.
[0261] First, in step S1105, a PSCCH resource pool and/or a PSSCH
resource pool related to a sidelink is configured by a higher
layer.
[0262] Thereafter, in step S1110, an eNB transmits information on
the PSCCH resource pool and/or the PSSCH resource pool to a
sidelink UE through higher layer signaling (e.g., RRC
signaling).
[0263] Thereafter, in step S1115, the eNB transmits control
information, related to the transmission of a PSCCH (i.e., SCI
format 0) and/or the transmission of a PSSCH (i.e., sidelink
communication data), to a sidelink transmitter UE through the DCI
format 5 respectively or together. The control information includes
information scheduling of the PSCCH and/or the PSSCH in the PSCCH
resource pool and/or the PSSCH resource pool. For example, resource
allocation information, an MCS level, a time resource pattern, etc.
may be included in the control information.
[0264] Thereafter, in step S1120, the sidelink transmitter UE
transmits the PSCCH (i.e., SCI format 0) and/or PSSCH (i.e.,
sidelink communication data) to a sidelink receiver UE based on the
information received in step S1115. In this case, the transmission
of the PSCCH and the transmission of the PSSCH may be performed
together, or the transmission of the PSSCH may be performed after
the transmission of the PSCCH.
[0265] Meanwhile, although not shown in FIG. 11, the sidelink
transmitter UE may request a transmission resource (i.e., PSSCH
resource) for sidelink data from the eNB, and the eNB may schedule
resources for the transmission of the PSCCH and the PSSCH. To this
end, the sidelink transmitter UE transmits a scheduling request
(SR) to the eNB, and a buffer status report (BSR) procedure may be
performed so that the eNB can determine the amount of resources
requested by the sidelink transmitter UE.
[0266] Sidelink receiver UEs may monitor a control information
pool. When control information related thereto is decoded, the
sidelink receiver UEs may selectively decode sidelink data
transmission related to the corresponding control information.
[0267] In contrast, Mode 2 refers to a method of a UE to randomly
select a specific resource in a resource pool in order to transmit
data or control information for sidelink communication. In
out-of-coverage and/or in-coverage, Mode 2 is applied.
[0268] In Mode 2, a resource pool for control information
transmission and/or a resource pool for sidelink communication data
transmission may be pre-configured or may be semi-statically
configured. A UE is provided with a configured resource pool (time
and frequency) and selects a resource for sidelink communication
transmission in a resource pool. That is, the UE may select a
resource for control information transmission in a control
information resource pool in order to transmit control information.
Furthermore, the UE may select a resource in a data resource pool
for the sidelink communication data transmission.
[0269] Furthermore, in sidelink broadcast communication, control
information is transmitted by a broadcasting UE. The control
information explicitly and/or implicitly indicates the location of
a resource for data reception in relation to a physical channel
(i.e., PSSCH) that carries sidelink communication data.
[0270] Sidelink Synchronization
[0271] A sidelink synchronization signal (sidelink synchronization
sequence, sidelink SS) may be used for a UE to obtain
time-frequency synchronization. In particular, in the case of out
of coverage of a network, control of an eNB is impossible. A new
signal and procedure for synchronization establishment between UEs
may be defined.
[0272] A UE that periodically transmits a sidelink synchronization
signal may be referred to as a sidelink synchronization source.
[0273] Each UE may have multiple physical-layer sidelink
synchronization identities (IDs). The number of physical-layer
sidelink synchronization IDs is 336 (i.e., 0 to 335). 336
physical-layer sidelink synchronization IDs may be divided into an
in-network coverage part ID set (id_net set, 0 to 167) and an
out-of-network coverage ID set (id_oon set, 168 to 335).
[0274] A sidelink synchronization signal includes a primary
sidelink synchronization signal (PSSS) and a secondary sidelink
synchronization signal (SSSS).
[0275] The PSSS is transmitted in two neighbor SC-FDMA symbols of
the same subframe. In this case, in order to generate the PSSS, if
physical-layer sidelink synchronization IDs are 0 to 167, a
Zadoff-Chu sequence having a root index of 26 is used. In other
cases, a Zadoff-Chu sequence having a root index of 37 is used.
[0276] In this case, a sequence configuring the PSSS is mapped to
the resource elements of an antenna port 1020 in the first slot of
a corresponding subframe according to Equation 1.
a k , l = d i ( n ) , n = 0 , , 61 k = n - 31 + N RB SL N sc RB 2 l
= { 1 , 2 normal cyclic prefix 0 , 1 extended cyclic prefix [
Equation 1 ] ##EQU00001##
[0277] Furthermore, the SSSS is transmitted in the two neighbor
SC-FDMA symbols of the same subframe. In this case, in order to
generate the SSSS, two sequences assuming a subframe 0, that is,
N.sub.ID.sup.(1)=N.sub.ID.sup.SL mod 168 and N.sub.ID.sup.(2)=.left
brkt-bot.N.sub.ID.sup.SL/168.right brkt-bot. for transmission modes
1 and 2, and a subframe 5 for transmission modes 3 and 4,
respectively, are used.
[0278] In this case, a sequence configuring the SSSS is mapped to
resource elements for the antenna port 1020 in the second slot of a
corresponding subframe according to Equation 2.
a k , l = d i ( n ) , n = 0 , , 61 k = n - 31 + N RB SL N sc RB 2 l
= { 4 , 5 normal cyclic prefix 3 , 4 extended cyclic prefix [
Equation 2 ] ##EQU00002##
[0279] Before transmitting a sidelink synchronization signal, a UE
may discover a sidelink synchronization source. Furthermore, when
the sidelink synchronization source is discovered, the UE may
obtain time-frequency synchronization through the received sidelink
synchronization signal from the discovered sidelink synchronization
source. Furthermore, the corresponding UE may transmit a sidelink
synchronization signal.
[0280] Furthermore, a channel for delivering system information
used for communication between UEs and synchronization-related
information along with synchronization may be necessary. The
channel may be referred to as a physical sidelink broadcast channel
(PSBCH).
[0281] Vehicle-to-Everything (V2X)
[0282] (1) Vehicle-to-Everything (V2X) Sidelink Communication
[0283] V2X sidelink communication includes communication between a
vehicle and all entities, such as vehicle-to-vehicle (V2V)
referring to communication between vehicles, vehicle to
infrastructure (V2I) referring communication between a vehicle and
an eNB or a road side unit (RSU), and vehicle-to-pedestrian (V2P)
referring to communication between a vehicle and UEs owned by
persons (pedestrian, bicycler, vehicle driver or passenger).
[0284] In this case, a wireless communication system supporting V2X
sidelink communication may include specific network entities for
supporting communication between a vehicle and all entities. For
example, the network entity may be an eNB, road side unit (RSU), a
UE or an application server (e.g., traffic safety server).
[0285] Furthermore, a UE performing V2X sidelink communication may
mean a vehicle UE (V-UE), a pedestrian UE, an RSU of an eNB type or
an RSU of a UE type in addition to a common handheld UE.
[0286] V2X sidelink communication may be directly performed between
UEs or may be performed through a network entity(s). V2X operation
modes may be classified according to a method of performing V2X
sidelink communication.
[0287] Terms used in V2X are defined as follows.
[0288] A road side unit (RSU): a road side unit (RSU) is a V2X
service-capable apparatus capable of transmission and reception to
and from a moving vehicle using V2I service.
[0289] Furthermore, the RSU is a fixed infrastructure entity
supporting a V2X application program and may exchange messages with
other entities supporting a V2X application program.
[0290] Pseudonymity: a condition in which data is not provided to a
specific subscriber without using additional information in the
processing of personally identifiable information (PII). A
technological and organization measures for separately maintaining
such additional information and guaranteeing non-attribution for a
subscriber that has been identified or that may be identified.
[0291] The RSU is a term frequently used in the existing ITS spec.
The reason why the term is introduced into 3GPP spec. is for
enabling the document to be read more easily in the ITS
industry.
[0292] The RSU is a logical entity that combines V2X application
logic with the function of an eNB (called eNB-type RSU) or a UE
(called UE-type RSU).
[0293] V2I Service: type of V2X service and an entity having one
side belonging to a vehicle and the other side belonging to
infrastructure.
[0294] V2P Service: V2X service type in which one side is a vehicle
and the other side is a device carried by a person (e.g., a
portable device carried by a pedestrian, bicycler, driver or follow
passenger).
[0295] V2X Service: 3GPP communication service type in which a
transmission or reception device is related to a vehicle.
[0296] V2V service, V2I service and V2P service may be further
classified depending on a counterpart who participates in
communication.
[0297] V2X enabled UE: UE supporting V2X service.
[0298] V2V Service: type of V2X service in which both sides of
communication are vehicles.
[0299] V2V communication range: a direct communication range
between two vehicles participating in V2V service.
[0300] V2X application program support type
[0301] A V2X application called vehicle-to-everything (V2X), as
described above, includes the four types of (1) vehicle-to-vehicle
(V2V), (2) vehicle-to-infrastructure (V2I), (3) vehicle-to-network
(V2N) and (4) vehicle-to-pedestrian (V2P).
[0302] FIG. 12 illustrates the type of V2X application to which the
present invention may be applied.
[0303] The four types of a V2X application may use "co-operative
awareness" providing more intelligent service for the final
user.
[0304] This means that entities, such as a vehicle, roadside
infrastructure, an application server and a pedestrian, can collect
knowledge of a corresponding area environment (e.g., information
received from other adjacent vehicle or sensor device) so that the
entities can process and share the corresponding knowledge in order
to provide more intelligent information, such as a cooperative
collision warning or autonomous driving.
[0305] Furthermore, the V2V applications expect adjacent UEs to
exchange V2V application information. The 3GPP transmission of a
message including V2V application information requires a UE to
obtain valid subscription and permission from a network
operator.
[0306] Transmission for a valid subscriber is provided regardless
of whether a UE is served by an E-UTRAN. A UE supporting the V2V
application transmits a message including 2V application
information (e.g., location, dynamic and attributes). Message
payload may be flexible in order to accommodate the amount of
various types of information.
[0307] The 3GPP transmission of a message including V2V application
information is chiefly based on broadcast as shown in FIG. 13. Such
3GPP transmission includes direct transmission between UEs due to a
restricted direct communication range and/or transmission between
UEs through a base structure supporting V2X communication, such as
RSX and application server.
[0308] FIG. 13 illustrates broadcast-based V2V communication to
which the present invention may be applied.
[0309] Vehicular to Vehicular (V2V)
[0310] An E-UTRAN enables adjacent UEs to exchange V2V-related
information using the E-UTRAN when a permission, grant and
proximity criterion is satisfied. A proximity criterion may be
configured to a worker.
[0311] Furthermore, a UE supporting the V2V application broadcasts
application layer information (e.g., as part of V2V service,
regarding a corresponding location, dynamic and attributes). V2V
payload needs to be flexible in order to accommodate different
information contents. The information may be periodically
broadcasted based on a configuration provided by an operator.
[0312] Vehicle-to-Infrastructure (V2I) Application
[0313] A UE supporting the V2I application transmits a message,
including V2I application information, to an RSU or a local-related
application server. The RSU and/or local-related application server
transmits a message, including V2I application information, to one
or more UEs supporting the V2I application.
[0314] A locally related application program server provides
services to a specific geographical area. The same or different
application programs may be provided because there are several
application program servers providing service to an overlap
area.
[0315] Vehicle-to-Network (V2N) Application
[0316] A UE supporting the V2N application communicates with an
application server supporting the V2N application. Both communicate
with each other through an EPS.
[0317] Vehicle-to-Pedestrian (V2P) Application
[0318] The V2P applications expect adjacent UEs to exchange V2P
application information. The 3GPP transmission of a message
including V2P application information requires a UE to obtain valid
subscription and permission from a network operator. Transmission
for a valid subscriber is provided regardless of whether a UE is
served by an E-UTRAN.
[0319] A UE supporting a V2P application transmits a message
including V2P application information. The V2P application
information is expected to be transmitted by a UE supporting the
V2X application in a vehicle (warning against a pedestrian) or a UE
supporting a V2X application related a vulnerable road user (e.g.,
warning against a vehicle).
[0320] The 3GPP transmission of a message including V2P application
information includes direct transmission between UEs due to a
restricted direct communication range and/or transmission between
UEs through an infrastructure structure supporting V2X
communication, such as an RSX or application server.
[0321] A major difference between the 3GPP transmission of a
message including V2P application information and the 3GPP
transmission of a message including V2V application information
lies in the characteristics of a UE. A UE supporting a V2P
application used by a pedestrian may have a lower battery capacity,
for example, and may have limited radio sensitivity due to the
antenna design. Accordingly, the UE cannot transmit a message
having the same periodicity as a UE supporting the V2V application
and/or also cannot receive a message.
[0322] Relative Priority of V2X Communication
[0323] Specific business core services (e.g., public safety, MPS)
may be relatively given priority over the transmission of V2X
application program information according to local/country
regulation requirements and an operator policy. The transmission of
safety-related V2X application information may have priority over
the transmission of V2X application program information not related
to safety.
[0324] However, in general, an operator may control relative
priority of different services.
[0325] Sidelink Communication-Related Identity (ID)
[0326] A sidelink communication and V2X sidelink
communication-related ID to which the present invention may be
applied is described.
[0327] The following IDs are used for sidelink communication.
[0328] Source Layer-2 ID: identify the sender of data in sidelink
communication. Source Layer-2 ID is a 24-bit length and is used
with a Destination Layer-2 ID and LCID in order to identify an RLC
UM entity and PDCP entity on the receiver side. [0329] Destination
Layer-2 ID: identify the target of data in sidelink communication
and V2X sidelink communication. In the case of sidelink
communication, the destination layer -2 ID is a 24-bit length and
is split into two bit streams in the MAC layer. [0330] One bit
string is the LSB part (8 bits) of a target layer 2 ID and
delivered to a physical layer as a group target ID. This is used to
identify the target of intended data in sidelink control
information and to filter a packet in the physical layer. [0331]
The second bit text string is the MSB part (16 bits) of a target
layer 2 ID and delivered within a MAC header. This is used to
filter a packet in the MAC layer. [0332] In the case of V2X
sidelink communication, a Destination Layer-2 ID is not split and
carried within a MAC header.
[0333] No Access Stratum signaling is necessary to form a group and
to configure the Source Layer-2 ID, Destination Layer-2 ID and
Group Destination ID of a UE.
[0334] Such an ID is provided by a higher layer and derived from an
ID provided by a higher layer. In the case of group cast and
broadcast, a ProSe UE ID provided by a higher layer is directly
used as a Source layer-2 ID, and a ProSe Layer 2 group ID provided
by a higher layer is directly used as a Destination layer-2 ID in
the MAC layer.
[0335] In the case of one-to-one communication, a ProSe UE ID and
V2X sidelink communication provided by a higher layer are directly
used as a Source layer-2 ID or Destination layer-2 ID in the MAC
layer.
[0336] V2X sidelink communication is described more
specifically.
[0337] The support of V2X service through the PC5 interface is
provided by V2X sidelink communication, that is, a communication
mode in which a UE can perform direct communication through the PC5
interface. The communication mode is supported when a UE is served
by an E-UTRAN and when a UE is out-of-E-UTRA coverage.
[0338] Only a UE permitted to be used in V2X service may perform
V2X sidelink communication. Furthermore, in the case of V2X
sidelink communication: [0339] A sidelink transport channel (STCH)
for sidelink communication is also used for V2X sidelink
communication. [0340] V2X data transmitted in a resource configured
for V2X sidelink communication is not multi-transmitted along with
non-V2X (e.g., public safety) data.
[0341] For sidelink communication, a control plane protocol stack
for an SBCCH is also used for V2X sidelink communication as shown
in FIG. 5b.
[0342] A UE supporting V2X sidelink communication may operate in
the two modes for resource allocation: [0343] Reserved resource
allocation. [0344] A UE needs to be in RRC_CONNECTED in order to
transmit data. [0345] A UE requests a transmission resource from an
eNB. The eNB schedules a transmission resource for the transmission
of sidelink control information and data. [0346] UE autonomous
resource selection. [0347] A UE autonomously selects a resource in
a resource pool and performs transmission format selection for
transmitting sidelink control information and data. [0348] When
mapping between a zone and a V2X sidelink transmission resource
pool is configured, a UE selects a V2X sidelink resource pool based
on the zone where the UE is located. [0349] A UE performs sensing
for the (re)selection of sidelink resources. Based on the results
of the sensing, the UE (re)selects some specific sidelink resources
and reserves a plurality of sidelink resources.
[0350] A maximum of two parallel independent resource reservation
processes are permitted to be performed by a UE. The UE is also
permitted to perform single resource selection for V2X sidelink
transmission.
[0351] A geographical area may be configured by an eNB or may be
pre-configured. When the area is configured, the world is divided
into geographical areas using a single fixing reference point
(i.e., geographical coordinates (0, 0)), length and width).
[0352] A UE determines a zone identity based on the length and
width of each zone, the number of zones in the length, and the
number of zones in the width, and modulo operation using single
fixing reference point.
[0353] The length and width of each zone, the number of zones in
the length, and the number of zones in the width are provided by an
eNB when a UE is in coverage and is pre-configured when the UE is
out of coverage.
[0354] This area may be configured both in a service area and
service area.
[0355] When a UE uses UE-autonomous resource selection with respect
to the UE in coverage, an eNB may provide mapping between the V2X
sidelink transmission resource pools between a zone(s) and an
SIB21.
[0356] With respect to UEs out of coverage, mapping between a
zone(s) and V2X sidelink transmission resource pools may be
pre-configured.
[0357] If mapping between a zone(s) and a V2X sidelink transmission
resource pool is (pre)configured, a UE selects a transmission
sidelink resource in a resource pool corresponding to a zone where
the UE is located.
[0358] The zone concept is not applied to a reception pool in
addition to an exceptional V2X sidelink transmission pool.
[0359] A resource pool for V2X sidelink communication is not
configured based on priority.
[0360] For V2X sidelink transmission, during handover, a
transmission resource pool configuration including an exceptional
transmission resource pool for a target cell may be signaled in a
handover command in order to reduce a transmission stop.
[0361] Accordingly, a UE may use the transmission sidelink resource
pools of the target cell before handover is completed as long as
synchronization with the target cell is performed.
[0362] If an exceptional transmission resource pool is included in
a handover command, the UE randomly starts to use a selected
resource in the exceptional transmission resource pool starting
from the reception of the handover command. When resource
allocation scheduled in the handover command is configured in the
UE, the UE continues to use the exceptional transmission resource
pool while a timer related to handover is executed. When autonomous
resource selection is configured in the UE in a target cell, the UE
continues to use the exceptional transmission resource pool until
initial sensing is completed in a transmission resource pool for
autonomous resource selection.
[0363] In an exceptional case (e.g., in a radio link failure (RLF),
during transition from RRC IDLE to RRC CONNECTED or during a change
in the dedicated sidelink resource pool of a cell), a UE may select
resources in an exceptional pool provided by the SIB 21 of a
serving cell based on sensing and may temporarily use them.
[0364] In obtaining a reception pool broadcasted by a target cell,
in order to avoid a stop time when a V2X message is received due to
latency, a synchronization configuration and reception resource
pool configuration for the target cell may be signaled in a
handover command with respect to RRC_CONNECTED UEs.
[0365] In the case of an RRC_IDLE UE, to minimize a sidelink
transmission/reception stop time related to the acquisition of the
SIB21 of a target cell depends on a UE implementation.
[0366] When a UE detects a cell on a corresponding carrier based on
a criterion, the carrier is considered to be in-coverage in a
carrier used for V2X sidelink communication.
[0367] If a UE permitted for V2X sidelink communication is in
coverage for V2X sidelink communication, it may use resource
allocation scheduled based on an eNB configuration or UE autonomous
resource selection.
[0368] When a UE is out of coverage for V2X sidelink communication,
a transmission and reception resource pool set for data is
pre-configured in the UE. A V2X sidelink communication resource is
not shared with another non-V2X application program transmitted
through a sidelink.
[0369] If an RRC_CONNECTED UE is interested in V2X communication
transmission in order to request a sidelink resource, it may
transmit a sidelink UE information message to a serving cell.
[0370] In order to receive V2X communication, when a UE is
configured by a higher layer and provided with a PC5 resource, the
UE receives a configured resource.
[0371] A serving cell may provide a synchronization configuration
for a carrier used for V2X sidelink communication. In this case, a
UE follows a synchronization configuration received from a serving
cell.
[0372] If a cell is not detected on the carrier used for V2X
sidelink communication and the UE does not receive the
synchronization configuration from the serving cell, the UE follows
a pre-configured synchronization configuration. A synchronization
criterion includes three types of an eNB, a UE and a GNSS. If the
GNSS is configured as a synchronization source, the UE uses UTC
time in order to calculate a direct frame number and subframe
number.
[0373] If eNB timing is set as a synchronization criterion for a UE
for a dedicated carrier for V2X, the UE follows a PCell
(RRC_CONNECTED)/serving cell (RRC_IDLE) for synchronization and DL
measurement.
[0374] PC5 Interface-Based V2X Operation Mode
[0375] FIG. 14 illustrates examples of a V2X operation mode based
on a PC5 interface only.
[0376] Referring to FIG. 14, a UE transmits a V2X message to a
plurality of UEs in the area where a sidelink is supported. In this
case, the V2X message means a message mutually transmitted by a
network entity or UE using a V2X sidelink communication system.
[0377] FIG. 14(a) means a V2V operation mode, FIG. 14(b) means a
V2I operation mode, and FIG. 14(c) means a V2P operation mode. In
this case, in the case of V2I, one of a transmitter UE or a
receiver UE is an RSU of a UE type. Furthermore, in the case of
V2P, one of a transmitter UE or a receiver UE is a pedestrian
UE.
[0378] Uu Interface-Based V2X Operation Mode
[0379] FIG. 15 illustrates examples of a V2X operation mode based
on a Uu interface only.
[0380] Referring to FIG. 15, FIG. 15(a) means a V2V operation mode,
FIG. 15(b) means a V2I operation mode, FIG. 15(c) means a V2P
operation mode, and FIG. 15(d) means a V2N operation mode.
[0381] In this case, there is a mode in which a UE(s) transmits
(uplink transmission) a message (e.g., V2X message, V2I message) to
a specific network entity (e.g., eNB, E-UTRAN) and a specific
network entity transmits (downlink transmission) a message (e.g.,
V2X message, I2V message) to a plurality of UEs located in a
specific area.
[0382] In this case, the specific network entity may be an eNB, an
E-UTRAN or an RSU of an eNB type.
[0383] Furthermore, the UE may communicate with an application
server.
[0384] Furthermore, in order to support a Uu interface-based V2X
operation mode, an E-UTRAN performs the uplink reception and
downlink transmission of V2X messages. For the downlink, the
E-UTRAN may use a broadcast mechanism.
[0385] Uu Interface and PC5 Interface-Based V2X Operation Mode
[0386] FIG. 16 illustrates examples of a V2X operation mode based
on both the Uu interface and the PC5 interface.
[0387] Referring to FIG. 16, FIG. 16(a) means a scenario 3A mode in
which an E-UTRAN receives a V2X message from a UE type RSU and
transmits the received V2X message to a plurality of UEs. In
contrast, FIG. 16(b) means a scenario 3B mode in which a UE
transmits a V2X message to an E-UTRAN, the E-UTRAN transmits the
received V2X message to one or more UE type RSUs, and a UE type RSU
transmits a V2X message to other UEs through a sidelink.
[0388] More specifically, if both the Uu interface and the PC5
interface are used, an RSU (e.g., an RSU of a UE type) is present
between UEs and a specific network entity. The RSU may receive a
message from the UEs or transmits a message to the UEs.
[0389] In this case, it is assumed that the RSU is connected to a
specific network entity.
[0390] The specific network entity may receive a message from the
UEs using the RSU or may transmit a message to the UEs. In this
case, the specific network entity may be an eNB, an E-UTRAN or an
RSU of an eNB type.
[0391] In this case, a specific network entity or RSU that receives
the message of the UEs may operate through the Uu interface (e.g.,
Uu vehicle-to-infrastructure (V2I)) using a legacy LTE uplink
method.
[0392] Alternatively, the specific network entity or the RSU may
operate through the PC5 interface (e.g., PC5 V2I or PC5 V2V signal
overhearing) using a separate resource or separate band supporting
communication between UEs.
[0393] Likewise, the specific network entity or RSU transmitting a
message to the UEs may operate through the Uu interface or the PC5
interface using a legacy LTE downlink method.
[0394] (2) Scheduling Scheme in V2V Sidelink Communication
[0395] In the case of V2V sidelink communication, an eNB
indication-based scheduling method (i.e., Mode 1) of sidelink
communication and a scheduling method (i.e., Mode 2) for a UE to
autonomously select a resource within a specific resource pool may
be used.
[0396] However, in V2V sidelink communication, Mode 3 corresponding
to Mode 1 and Mode 4 corresponding to Mode 2 are defined so that
they are different from those in the case of the existing sidelink
communication.
[0397] In this case, Mode 3 may be referred to as a distributed
scheduling method, and Mode 4 may be referred to as an eNB
scheduling method.
[0398] In particular, sensing based on a semi-persistent
transmission-based mechanism may be defined with respect to the
distributed scheduling method (i.e., Mode 4). Most of V2V traffic
from a UE is periodical. The V2V traffic is used to sense
congestion for a resource and to estimate a future congestion for a
corresponding resource. Corresponding resources are booked based on
the estimation. The use of a channel can be optimized by improving
separation efficiency between transmitters using an overlap
resource through such a technology.
[0399] A configuration 1 for Mode 4 (i.e., distributed scheduling)
and a configuration 2 for Mode 3 (i.e., eNB scheduling) may be
represented like FIG. 17.
[0400] FIG. 17 illustrates examples of scheduling methods which may
be applied to V2V sidelink communication.
[0401] Referring to FIG. 17, two configurations use a V2V
communication dedicated carrier. That is, a band for the dedicated
carrier is used for only PC5-based V2V communication. In this case,
FIG. 17(a) illustrates a method for the configuration 1, and FIG.
17(b) illustrates a method for the configuration 2.
[0402] In this case, in both cases, time synchronization may be
performed by a global navigation satellite system (GNSS).
[0403] FIG. 17(a), that is, in the case of the configuration 1, the
scheduling and interference management of V2V traffic is supported
based on a distributed algorithm (i.e., Mode 4) implemented between
vehicles. As described above, the distributed algorithm is based on
sensing through semi-persistent transmission. Furthermore, a
mechanism in which resource allocation depends on geographical
information is defined.
[0404] In contrast, FIG. 17(b), that is, in the case of the
configuration 2, the scheduling and interference management of V2V
traffic is supported by an eNB through control signaling through
the Uu interface. The eNB allocates resources used for V2V
signaling in a dynamic manner.
[0405] As described above, in order to perform direct communication
between UEs through Sidelink and the like, an eNB may select and
indicate a resource to transmit a message, and signal the related
control message and the like for the UE. As such, the scheme that
an eNB indicates and signals may be referred to as network-assisted
scheme and/or mode 1 scheme. Different from this, the scheme that a
UE directly selects a resource may be referred to as UE-autonomous
scheme and/or mode 2 scheme. In addition, in the case of the V2X
Sidelink communication, the mode 1 scheme may be referred to as
mode 3 scheme and the mode 2 scheme may be referred to as mode 4
scheme.
[0406] When a communication is performed between UEs, the UE needs
to transmit Scheduling Assignment (SA) that designates resource
allocation information and the like for transmission data in
Sidelink resource selection and scheduling to another UE. In
addition, in the case of the mode 1 scheme, an eNB transmits
Downlink Control Information (DCI) that designates information for
SA and information for transmission data to a UE. Here, the DCI may
include a part of information for SA transmission and contents of
SA (i.e., information related to data transmission). Furthermore,
the DCI may be referred to as Sidelink grant, and the SA may be
referred to as Sidelink Control Information (SCI).
[0407] At this time, pattern for transmitting SA and/or data (e.g.,
time/frequency resource pattern) and/or information for scheduling
scheme and the like may be added as a specific field of the DCI. In
this case, a part of the DCI format designed with the same size as
the existing DCI format (i.e., DCI format 0) may be changed. For
example, when SA and/or data is retransmitted, in the case that an
eNB transmits only DCI for an initial transmission, not
transmitting DCI in each retransmission (or transmission), the eNB
needs to inform the information for remaining SA and/or data. Here,
the transmission of only the DCI for the initial transmission may
be designed for reducing DCI overhead.
[0408] As described above, while an addition of specific field(s)
for DCI is considered, in the case that the fields for the
parameters previously existed are maintained without any change, a
length (i.e., size) of DCI is increased. In this case, as a size
changes for each DCI format, a problem may occur that count and/or
type of blind decoding performed in a UE is changed. That is, in
the case that a size of DCI format is not regularly configured for
each format, overhead of blind decoding of UE may be increased.
[0409] Accordingly, a method of maintaining a size of DCI format
(i.e., the size is configured as the same as DCI format 0) needs to
be considered even in the case that new fields are added in DCI. In
this case, a method of adding new fields may be considered while a
part of existing fields in the existing DCI is deleted or
constricted.
[0410] At this time, the value indicated in the corresponding field
(i.e., deleted or constricted field) may be indicated to a UE by
using other signaling or other field which may be replaced. Here,
the other field which may be replaced may mean a newly added field
as well as the existing fields in the existing DCI.
[0411] Hereinafter, in the present disclosure, a method for
configuring a DCI format used for V2X Sidelink communication will
be described in detail.
[0412] As described above, the DCI is information used for
scheduling SA (or SCI or PSCCH), and the SA is information used for
scheduling (Sidelink) data (or PSSCH).
[0413] In addition, in the case of the Sidelink communication, the
DCI format that an eNB transmits to a transmission UE may be
represented as DCI format 5, and the SA that a transmission UE
transmits to a reception UE may be represented as SCI format.
[0414] Particularly, in the case of the V2X Sidelink communication,
the DCI format that an eNB transmits to a transmission UE may be
represented as DCI format 5A, and the SA that a transmission UE
transmits to a reception UE may be represented as SCI format 1.
However, this is just an example, but not limited to the
representation, and may be represented in various forms. For
example, the DCI format used for the V2X Sidelink communication may
be represented as DCI format 5, DCI format 5A, modified DCI format
5 or new DCI format 5, and the like.
[0415] In addition, hereinafter, the description described in
relation to the present invention may also be extendedly applied to
other wireless communication operates in the same way as well as
the V2X Sidelink communication.
[0416] In this case, as described above, even in the case that
additional information (i.e., additional field), which was not
existed in the DCI format, is included, the methods for maintaining
a length (i.e., size) of the DCI format as the same as the existing
case are described in the present disclosure.
[0417] Furthermore, the methods described in the present disclosure
may be applied as a method for reducing a size of the general DCI
format as well as a method for maintaining a size of the DCI format
which is used for the V2X Sidelink communication. The reducing of a
size of the DCI format itself may mean that an amount of resource
(e.g., radio resource, power, transmission time, etc.) consumed for
transmitting the DCI is reduced. Accordingly, when a size of the
DCI format is reduced, an eNB may perform scheduling more
efficiently in an aspect of resource.
[0418] In addition, the embodiments described below are
distinguished for the convenience of description, but a part of the
configuration of any one embodiment may be included in the other
embodiment, or may be replaced by the configuration or the
characteristics corresponding to the other embodiment.
[0419] Method for reducing a size of a field related to SA and/or
resource of data
[0420] In order to maintain a size of DCI while a new field is
added to the DCI, a method for reducing a size of the SA resource
field (i.e., resource field for Physical Sidelink Control Channel
(PSCCH)) included in the existing DCI may be considered.
[0421] In comparison with the existing case (e.g., Sidelink
communication between normal UEs), the number of resources usable
for V2X communication or SA transmission in V2V communication may
not be changed or only a few of it may be changed. In this case,
there is little possibility that a size (e.g., 6 bits) of the field
indicating the SA resource defined in the existing DCI format
(e.g., DCI format 5/5A) with the change of the scheme of
multiplexing SA and/or data (e.g., Frequency Division Multiplexing
(FDM) scheme and Time Division Multiplexing (TDM) scheme) only.
[0422] However, in the case that a UE may know a part or the whole
of allocation information for time/frequency resource of SA
transmission, may be indicated with the information from an eNB and
the like, or may estimate it autonomously, the size of the field
indicating the SA resource may be reduced. That is, a method of
reducing the field indicating the SA field using predefined
information (i.e., advance information) or implicit information
(configuring the size of the field indicating the SA resource to
smaller than 6 bits).
[0423] For example, in the case that it is configured that SA is
transmitted after a specific time offset (or timing gap, subframe
offset) based on a transmission position of DCI, the information
for the time resource of SA transmission is not required to be
included in the DCI. As an example, in the case that the DCI is
transmitted in subframe #n, it may be configured that SA is
transmitted in subframe #n+k.
[0424] Here, the configuration information for the specific timing
offset may be predefined (predetermined or preconfigured) on a
system or an eNB may inform the configuration information through
signaling (e.g., higher layer signaling) to a UE. As an example,
this method may be performed as shown in FIG. 18.
[0425] FIG. 18 illustrates an example of SA transmission scheme.
FIG. 18 is shown just for the convenience of description, but does
not limit the scope of the present invention.
[0426] Referring to FIG. 18, each of the squares depicted means a
subframe, and the case is assumed that SA is transmitted in 4th
subframe after DCI transmission. Particularly, in the case that the
DCI is transmitted in subframe #n 1802, it may be configured that
SA is transmitted in subframe #n+4 1804. Alternatively, different
from FIG. 18, it may be configured that SA is transmitted in the
first Sidelink subframe existed (or generated) after subframe #n+4
1804.
[0427] As described above, in the case that the SA transmission is
configured to be transmitted after a specific timing offset (or
timing gap) based on a transmission position of the DCI, the eNB
may indicate only frequency resource allocation information of the
SA transmission to the UE using the DCI. In addition, in the case
that the SA transmission is configured to be performed at a
position departed from as much as a specific timing offset and/or a
specific frequency offset based on a transmission position of the
DCI, the eNB may transmit the DCI in which time resource allocation
information and/or frequency resource allocation information are/is
excluded to the UE. In other words, since a part of resource
allocation information may be excluded from the DCI based on
time/frequency relationship between the DCI transmission and the SA
transmission, a size of the field indicating the SA resource may be
reduced in comparison with the existing DCI.
[0428] Alternatively, in the case that SA and data are multiplexed
in the FDM scheme and/or SA is transmitted in a sub-channel unit
including a regular number of resource blocks (RBs), a size of the
frequency resource allocation information of the SA transmission
may be reduced.
[0429] In addition, the method described above may reduce the size
of the field indicating the SA resource, and may also be
efficiently applied to the case that V2X communication or V2V
communication uses wide band on frequency (i.e., supports wide
bandwidth). Particularly, uncertainty of SA detection may be
reduced as specific time/frequency offset is used between the DCI
transmission and the SA transmission, and accordingly, an efficient
SA scheduling may be performed in the FDM scheme.
[0430] Further, in relation to the resource information included in
the DCI, a method of reducing a size of RB assignment filed as well
as the SA resource field may be considered. The RB assignment filed
included in the existing DCI field is configured to distinguish the
cases of all combinations between the timing when the RB assignment
is started and the timing (or the number of assigned RBs) when the
RB assignment is ended.
[0431] At this time, in the case that a UE may estimate (or infer)
the number of RBs assigned by signaling, indication or other field
included in the DCI from an eNB and the like, the size of the RB
assignment field may be reduced. Alternatively, even in the case
that a UE may know a starting point of the RB assignment through
interrelationship between frequency assignment schemes of SA and
data, the size of the RB assignment field may be reduced. In this
case, the number of RBs (i.e., RB size) may be predefined depending
on types of V2V or V2X message which is used for the data
transmission. In addition, in the case that a resource allocation
unit for data is transmitted in a sub-channel unit including a
regular number of RBs, the size (i.e., bit number) of the RB
assignment field may be changed as the resource allocation unit is
changed.
[0432] Method for Indicating Modulation and Coding Scheme (MCS)
Index
[0433] For the mode 1 scheme described above, Semi-Persistent
Scheduling (SPS) as well as dynamic scheduling may be considered
for data transmission between UEs. In this case, a common (or
single) DCI (or DCI format) may be configured, which may be applied
to both of the two (or more) types of scheduling scheme. Separate
DCIs may be configured for each scheduling scheme, but in order to
reduce complexity of DCI (i.e., in order to reduce blind decoding
count and/or types of UE), the common DCI may be used for the
scheduling schemes. The common DCI may also be referred to as mode
1 Sidelink DCI or mode 1 Sidelink grant.
[0434] At this time, in the case of the dynamic scheduling scheme,
information of specific DCI is used once or for transmissions of
associated data (or only for a specific transmission period).
Different from this, in the case of the SPS scheme, information of
specific DCI may be used until the corresponding SPS transmission
operation is released. Accordingly, in order to common DCI for two
types of scheduling scheme, a field indicating a valid period of
the corresponding DCI may be additionally included. Here, the field
indicating a valid period of the corresponding DCI may mean a field
that distinguishes how long period the corresponding DCI is valid.
For example, the field indicating a valid period of the
corresponding DCI may include a field that distinguishes dynamic
scheduling from SPS.
[0435] In the case that dynamic transmission and SPS transmission
are distinguished using the field, a specific field may be
configured in accordance of each of the uses for the dynamic
transmission and the SPS transmission. In this case, a UE may
interpret (or use) the corresponding specific field according to
each of the uses for the dynamic transmission and the SPS
transmission. Alternatively, a part or the whole of the remaining
fields except the field that distinguishes the dynamic scheduling
and the SPS may be differently configured (or defined) for the
dynamic transmission and the SPS transmission.
[0436] For example, in the case that the field that distinguishes
the dynamic scheduling and the SPS is configured as 1 bit, 0 may
indicate that the corresponding DCI is for the dynamic scheduling.
That is, 0 may indicate the DCI defined only for one-shot
transmission or the associated transmission (or retransmission).
Different from this, 1 may indicate that the corresponding DCI is
for the SPS. Accordingly, when a UE receives the DCI configured as
1, the corresponding UE may operate based on the SPS transmission.
That is, the UE may transmit SA and/or data indicated by the
corresponding DCI during the previously configured and/or a
predetermined period indicated by signaling (e.g., RRC signaling),
and the like or until the corresponding SPS transmission operation
is released.
[0437] In relation to the predetermined period, the UE may count
the number of SA and/or data being transmitted and perform a
transmission of SA and/or data until a corresponding timer expires.
Alternatively, the UE may count time lapsed from the timing when
the DCI is transmitted and perform a transmission of SA and/or data
until a corresponding timer expires.
[0438] As described above, in the case that the SPS transmission as
well as the dynamic transmission is scheduled using a common DCI
(i.e., the same DCI format), various types of messages may be
transmitted in the aspect of a size of message block, a size of
transport block, and the like. Accordingly, an eNB is required to
designate the Modulation and Coding Scheme (MCS) applied to the
various types of messages.
[0439] In this case, the eNB may indicate an MCS index in
semi-static manner for a UE through higher layer signaling (e.g.,
RRC signaling) and the like.
[0440] Alternatively, the MCS index is included in the existing SA
(i.e., SCI format), but a method of including a field indicating
information for the MCS in the DCI may be considered so as to a UE
may detect MCS level even in the case that the UE fails to receive
the SA. Particularly, in the case that the DCI includes a field
indicating information for the MCS, even in the case that the UE
performing SPS transmission fails to receive the SA, the UE may
detect a change of the MCS using the DCI.
[0441] For example, like DCI format 0, a field indicating the MCS
(i.e., MCS index) or MCS and redundancy version may be included in
the DCI which is used for Sidelink (or V2X, V2V) communication. At
this time, the corresponding field may be configured with 5 bits
considering the usable MCS level.
[0442] For another example, by using the characteristics that
transmittable types of message is limited for Sidelink (or V2X,
V2V) communication, a method of reducing a size of the field
indicating the MCS index may be used (i.e., configuring a size of
the field indicating the MCS index to be smaller than 5 bits). In
the case of using the field of which size is reduced, an eNB may
indicate the MCS index for a transmission of the message related to
the corresponding DCI to a UE by using the remaining bits which are
occurred owing to the reduction of size of other fields included in
the DCI. That is, in the case of using the method, there is an
advantage that a size of the existing DCI may be maintained even in
the case that the remaining bit is configured smaller.
[0443] Particularly, the eNB may transmit the DCI including an
additional field indicating the MCS index and the like to the UE.
In other words, the DCI may include a separate field indicating a
specific message among the messages which are categorized according
to the MCS index, a size of message, and the like. Here, the
specific message may mean a set of specific messages which are
selected among preconfigured multiple message sets.
[0444] In the case of the dynamic scheduling transmission, various
types of messages may be transmitted in comparison with the SPS
transmission. However, such V2V and/or V2X message transmission is
performed in broadcast manner mainly, not a transmission to a
specific UE. Therefore, the types of messages transmitted in the
V2V and/or V2X communication (or Sidelink communication) may be
limited. Accordingly, a method may be used that an eNB indicates
only a part of MCSs corresponding to the limited types of messages.
In addition, based on the characteristics of performing repeated
transmission of the SPS transmission, when the MCS satisfying a
predetermined level, a message transmission may be smoothly
performed. Accordingly, in the case of the SPS transmission, even
in the case that a specific MCS is indicated among a part of MCSs
proper for the SPS transmission, not the whole MCSs, a message
transmission may be performed without any problem.
[0445] As described above, in the case of the V2V and/or V2X
communication (or Sidelink communication), only a part of the MCS
indexes may be selectively used among the usable MCS indexes for a
message transmission, and only a part of the whole transport block
sizes may be selectively used. Furthermore, when sizes of the MCS
index and the transport block used for the message transmission are
determined, a size of resource block (RB) to be used for the
message transmission may also be determined. Alternatively, the MCS
index may be determined after the size of resource block and the
size of transport block are determined, and any combinations of the
order of determining thereof are available.
[0446] As such, the MCS (i.e., MCS index) required for a type of
transmitted message, a size of transport block (TB size), a size of
resource block (RB size), and the like may be predefined, and made
up as a set. That is, according to the MCS required for a type of
message used in the V2V and/or V2X communication, a size of
transport block, a size of resource block, and the like, one or
more message sets may be predefined (or preconfigured or
predetermined). In this case, even in the case that a UE detects a
set of messages indicated by the corresponding DCI, the UE may
obtain the information for the MCS level required for a
transmission of the corresponding message, a size of transport
block and a size of resource block.
[0447] In addition, in the case that a coding rate (i.e., coderate)
of the corresponding message is not sufficient or the corresponding
message has an importance to be transmitted repeatedly, the
corresponding message is configured to be transmitted repeatedly.
In this case, the information for the (maximum) retransmission
count, the coding rate, and the like may be additionally included
in addition to the MCS (i.e., MCS index), a size of transport
block, a size of resource block, and the like.
[0448] As an example, the message sets may be configured as
represented in Table 3 below.
TABLE-US-00003 TABLE 3 Message Message Set size N_rpt N_PRB I_TBS
I_MCS Q_m Coderate 1 190 Byte 3 10 9 (1544 bit) 9 2 0.268 2 300
Byte 2 10 13 (2536 bit) 14 4 0.330 3 800 Byte 2 25 13 (6456 bit) 14
4 0.336 4 1600 Byte 2 50 13 (12960 bit) 14 4 0.338 . . . . . . . .
. . . . . . . . . . . . .
[0449] In Table 3, `Message size` means a size of the corresponding
message, `N_rpt` means a number of repetition transmissions of the
corresponding message, `N_PRB` means the number of resource block
(i.e., a size of resource block) used for transmitting the
corresponding message, `I_TBS` means an index (size) of the
transport block used for transmitting the corresponding message,
`I_MCS` means an MCS index used for transmitting the corresponding
message, `Q_m" means a modulation order used for transmitting the
corresponding message, and `coderate` means a code rate of the
corresponding message.
[0450] At this time, as represented in Table 3, in the case that 4
types of message sets (i.e., a first message set (Message set 1), a
second message set (Message set 2), a third message set (Message
set 3) and a fourth message set (Message 4)) are configured, a
message set field configured with a combination of a size of
message, a number of repetition transmissions, the number of
resource block, and the like may be configured with 2 bits. Here,
the message set field may mean a separate field indicating the MCS
index, and the like included in the DCI. At this time, in the case
that the message set field is configured with 2 bits, the first
message set is indicated by `00`, the second message set is
indicated by `01`, the third message set is indicated by `10` and
the fourth message set is indicated by `11`. That is, the MCS index
used for transmitting the corresponding message may be indicated by
using 2 bits only which is decreased by 3 bits in comparison with
the existing 5 bits.
[0451] In this case, the configuration information for the message
set described above may be predefined on a system, or the
configuration information for the message set may be transmitted to
a UE through higher layer signaling, and the like. In addition, the
configuration information for the message set may be configured
with a combination of various parameters related to the
corresponding message types as well as a size of message, a number
of repetition transmissions, the number of resource block, and the
like.
[0452] Further, in the various embodiments, the retransmission
count (e.g., N_rpt) used for V2V and/or V2X communication may be
indicated by Time-Resource Pattern of Transmission (T-RPT) field
and so on included in a new field indicating the message set or the
existing DCI (e.g., DCI format 5). In addition, in the case that
the new field and the T-RPT field are not used, the retransmission
count may be indicated through higher layer signaling (e.g., RRC
signaling), or a separate field indicating the retransmission count
may be included in the DCI.
[0453] FIG. 19 illustrates an operation flowchart for a first UE to
transmit and receive data in a wireless communication system
supporting Vehicle-to-Everything (V2X). FIG. 19 is shown just for
the convenience of description, but not intended to limit the scope
of the present invention.
[0454] Referring to FIG. 19, the case is assumed that a first UE
receive a resource selection and an indication for scheduling
through downlink control information from an eNB in order to
perform Sidelink communication (i.e., Device-to-Device
communication) with a second UE.
[0455] In step S1905, the first UE receives downlink control
information (DCI) including resource allocation information related
to a transmission of control information (e.g., SA) with respect to
Sidelink from the eNB. At this time, the corresponding resource
allocation information may mean the SA resource allocation
information of which size is adjusted (i.e., the bit number is
configured smaller than the SA resource allocation information
included in the existing DCI) described above.
[0456] After the first UE receives the DCI, in step S1910, the
first UE may transmit Sidelink control information and at least one
data (i.e., data transmitted through Sidelink, Sidelink data) to
the second UE. In this case, the transmission of the at least one
data may be performed after the transmission of control information
with respect to Sidelink or performed simultaneously.
[0457] At this time, the transmission of control information with
respect to Sidelink is performed in a second subframe located after
a preconfigured offset from a first subframe in which the DCI is
received. Here, the preconfigured offset may mean a specific timing
offset described in the first embodiment described above. That is,
the preconfigured offset may be configured based on the
relationship between a reception position of the DCI (or DCI
transmission position in the aspect of an eNB) and a transmission
position of the control information with respect to Sidelink. In
addition, the second subframe may include a first Sidelink subframe
located after a preconfigured offset from the first subframe. That
is, the first subframe is subframe #n, the second subframe may
include subframe #n+4 (e.g., n+4th subframe) or a first (or
initial) subframe generated after the subframe #n+4.
[0458] In this case, the resource allocation information included
in the DCI may include resource allocation information of which
size is adjusted based on at least one of the preconfigured offset
or a transmission unit (e.g., sub-channel unit including a
preconfigured (i.e., predetermined) number of RBs) on the frequency
domain related to the transmission of control information with
respect to the Sidelink. For example, the resource allocation
information included in the DCI may mean resource allocation
information of which size is adjusted (e.g., configured with a bit
number smaller than 6 bits) as the time resource allocation
information is excluded according to the preconfigured offset. At
this time, the bit number configuring the DCI format related to the
DCI may be configured as the same bit number configuring other DCI
format (e.g., DCI format 0). That is, a length of the DCI format
may be identically configured with the length of DCI format 0.
[0459] In addition, the DCI may further include specific
information (i.e., specific field) indicating an MCS index for the
at least one data transmission. For example, a separate field
indicating the MCS described in the second embodiment above in the
DCI may be additionally included.
[0460] In this case, the specific information may include
information indicating a specific message set among preconfigured
message sets. Here, the preconfigured message sets may mean the
message sets described in the second embodiment above. In other
words, the preconfigured message sets may be configured based on at
least one of an MCS index required related to a transmission of at
least one data, the number of transport blocks, or the number of
resource blocks. At this time, the specific information may be
configured with a bit number smaller than 5 bits, and the bit
number configuring the DCI format related to the DCI may be
identically configured with the bit number configuring other DCI
format (e.g., DCI format 0).
[0461] Further, the DCI may further include control information
with respect to the Sidelink and information indicating whether the
transmission of at least one data is performed according to the SPS
scheme (e.g., a field indicating a valid period of the
corresponding DCI in the second embodiment).
[0462] According to the methods described above, the size of the
DCI (e.g., mode 1 sidelink grant) used in V2V and/or V2X
communication may be identically configured with the size of the
existing other DCI (e.g., DCI format 0). Accordingly, even in the
case that additional information required for V2V and/or V2X
communication is included in the DCI, a UE may perform the blind
decoding for the DCI, which was performed for the existing DCI, in
the same manner. That is, even in the case that additional
information required for V2V and/or V2X communication is included
in the DCI, a UE is not required to perform additional blind
decoding in comparison with the previous case, and there is an
advantage that DCI overhead does not occur.
[0463] Hereinafter, a method for determining transmission timing
for SA transmission and data transmission in V2X Sidelink
communication proposed in the present disclosure is described in
detail with reference to the related drawing.
[0464] As described above, (1) DCI is information used for
scheduling SA (or SCI or PSCCH) and (2) SA is information used for
scheduling (Sidelink) data (or PSSCH), defined in Sidelink
communication.
[0465] In addition, in the case of Sidelink communication, the DCI
format transmitted to a transmission UE from an eNB may be
represented as DCI format 5, and the SA transmitted to a reception
UE from a transmission UE may be represented as Sidelink Control
Information (SCI) format.
[0466] Particularly, in the case of V2X Sidelink communication, the
DCI format transmitted to a transmission UE from an eNB may be
represented as DCI format 5A, and the SA transmitted to a reception
UE from a transmission UE may be represented as Sidelink Control
Information (SCI) format 1.
[0467] However, this is just an example, and not limited to the
representation, but may be represented as various forms.
[0468] Hereinafter, the description described in relation to the
present invention may also be extendedly applied to other wireless
communication operates in the same way as well as the V2X Sidelink
communication.
[0469] First, the method proposed in the present disclosure in V2X
Sidelink communication may be classified into a first embodiment
and a second embodiment largely according to a use (or
transmission) of T-RPT field, and the first embodiment and the
second embodiment may be applied together as occasion demands.
[0470] The DCI format used for V2X Sidelink communication includes
a part of contents of the SA.
[0471] Here, the DCI format may be represented as DCI format 5 or
DCI format 5A, or modified DCI format 5 or new DCI format 5, and
the like.
[0472] A part of the contents of the SA included in the DCI format
may include a field indicating T-RPT index that represents a
pattern for a repeated transmission or a retransmission of
data.
[0473] Here, the term, `pattern` may be interpreted as the same
meaning as a regular form or a specific form, and the like.
[0474] Particularly, in the DCI used in Mode 1 Sidelink
communication, it may be classified into the first embodiment and
the second embodiment as below according to use of the T-RPT
field.
[0475] Mode 1 Sidelink, as described above, is a network-assisting
scheme that an eNB directly indicates or signals the Sidelink
communication related information to a UE, and may also be
represented as Mode 3 in V2X Sidelink communication.
Embodiment 1: (Re)Use T-RPT Field
[0476] First, a first embodiment is in relation to a method for
(re)using T-RPT field included in the DCI of the existing Sidelink
communication for V2X Sidelink communication.
[0477] That is, in the case that the T-RPT field is used in V2X
Sidelink communication without any change, all of information for a
repeated transmission of data may be indicated in single DCI (up to
4 retransmissions).
[0478] In other words, for a repeated transmission of V2X Sidelink
communication of a transmission UE, an eNB transmits V2X sidelink
DCI including T-RPT field to the transmission UE.
[0479] By using the T-RPT field, a transmission UE is able to
(repeatedly) transmit a message or data to a reception UE on
various timings, and flexibility of resource allocation may become
significantly increased.
[0480] Particularly, in the case that the T-RPT field is used in
the DCI of V2X Sidelink communication, a part of resource
collision, half-duplex problem, and the like, which may occur by
using different T-RPTs between UEs, may be solved.
[0481] Here, as a method of interpreting the T-RPT pattern and
applying it to an actual data transmission, largely, (1) a method
of applying the T-RPT pattern based on SA transmission timing
(method 1) and (2) a method of applying the T-RPT pattern based on
a predetermined offset from DCI transmission timing (method 2) may
be considered.
[0482] (Method 1: Application of T-RPT Pattern Based on SA
Transmission Timing)
[0483] FIG. 20 illustrates a method for determining a transmission
timing of data using T-RPT pattern proposed in the present
disclosure.
[0484] Particularly, FIG. 20a illustrates an example of a method
for determining data transmission timing based on SA transmission
timing.
[0485] That is, method 1 relates to a method of synchronizing a
starting position of data transmission according to T-RPT pattern
with a starting position of SA transmission, and the corresponding
method provides a method for solving the situation that a UE is
unable to transmit data when the UE fails to obtain a starting
position of data transmission in the out-of coverage scenario.
[0486] For example, a case may occur that a UE operating mode 2
fails to obtain the information related to data transmission
starting point through SIB, RRC signaling or DCI from an eNB.
[0487] In this case, a problem may occur that the UE is unable to
(re)transmit data.
[0488] Accordingly, method 1 defines such that data transmission
timing is synchronized with transmission timing of SA.
[0489] When applying method 1, it is assumed that the SA includes
T-RPT pattern, and it is assumed that a UE operating in Mode 1 (or
Mode 3) generates SA through DCI and a UE operating in Mode 2 (or
Mode 4) obtains SA in advance or generates SA independently (if it
is required).
[0490] Particularly, the situation in which method 1 is applied may
be as below.
[0491] In the case that a first UE receiving information related to
data transmission starting point through SIB or RRC signaling, and
the like transmits SA to a second UE that fails to receive
information related to the data transmission starting point, the
second UE interprets that the T-RPT pattern included in the SA is
applied from the SA transmission timing.
[0492] That is, the first UE starts a transmission of data on a
subframe which is the same as the subframe for transmitting the SA
to the second UE.
[0493] In addition, the second UE may assume that data is
(re)transmitted according to the T-RPT pattern from the SA
transmission timing.
[0494] Here, the first UE is a UE that is able to receive
information related to the data transmission starting timing from
an eNB, and may be a UE that operates in Mode 1 (or Mode 3), and
the second UE is a UE that is unable to receive information related
to the data transmission starting timing from an eNB, and may be a
UE that operates in Mode 2 (or Mode 4).
[0495] And, it is assumed that the second UE may receive SIB or RRC
signaling, but when applying method 1, the second UE is unable to
receive SIB or RRC signaling including the information related to
data transmission starting timing.
[0496] In addition, a single SA may schedule a single Transport
Block (TB).
[0497] The contents related to method 1 described above may be
identically applied to method 2 (determining data transmission
timing considering a relationship with DCI transmission timing)
that will be described below.
[0498] For example, according to method 1, the DCI is transmitted
in subframe (SF) #n, the SA is transmitted SF #(n+k) (e.g., k=4),
and the T-RPT pattern indicated by the SA is applied from SF #(n+k)
timing.
[0499] The T-RPT pattern indicated by the SA may be included in the
DCI which is transmitted on SF #n.
[0500] Referring to FIG. 20a, an eNB may transmit the DCI to a
transmission UE on subframe (SF) #n 2001, and the transmission UE
may transmit the SA to a reception UE on SF #(n+k) (e.g., k=4)
2002.
[0501] At this time, the transmission UE may transmit data related
to the SA to the reception UE by applying the T-RPT pattern
indicated by the SA from the timing when the SA is transmitted,
that is, SF #(n+k) timing.
[0502] It may be interpreted that the T-RPT pattern represents a
specific form or a regular form of the time resource for a data
transmission.
[0503] That is, the T-RPT pattern is a concept representing a form
for a plurality of data resources, and a plurality of data
resources may include repeated data resource or retransmitted data
resource.
[0504] For example, as shown in FIG. 20a, in the case that the
T-RPT pattern is `00101011` (2003), an applying timing of data
transmission is SF #n+4 (2004) on which the SA is transmitted.
[0505] That is, the subframe on which data transmission is started
is the same as the subframe on which the SA is transmitted.
[0506] In addition, the timing when an actual data transmission
occurs may be SF #(n+k+2)(2005), SF #(n+k+4)(2006), SF
#(n+k+6)(2007) and SF #(n+k+7)(2008) as shown in FIG. 20a.
[0507] In FIG. 20a, k is 4, and total (re)transmission count of
data is 4 times.
[0508] Next, a case of (re)transmitting data using a plurality of
SAs is described with reference to FIG. 20b and FIG. 20c.
[0509] FIG. 20a shows the case that a transmission or a
retransmission of all data is performed after a single SA
transmission.
[0510] Different from FIG. 20a, a plurality of SAs may be used for
a transmission or a retransmission of all data.
[0511] That is, referring to FIG. 20b and FIG. 20c, it is shown
that a part of data (re)transmission is performed after the first
SA transmission, and (re)transmission for the remaining data is
performed through the next SA (or the second SA) transmission.
[0512] In FIG. 20a and FIG. 20c, it is assumed that data is
(re)transmitted twice times per a single SA.
[0513] As shown in FIG. 20b, the second SA transmission timing
transmitted after the first SA transmission may be obtained from a
timing gap between the first SA transmission timing and the first
data transmission timing.
[0514] The timing gap may be represented as an offset, and the
timing gap may be defined in a subframe unit.
[0515] However, when the method shown in FIG. 20b is applied,
before all of the first SA transmission 2010 and the data 2020
related to the first SA transmission are transmitted, the second SA
2030 may be transmitted, and accordingly, the case may occur that
the data associated with the first SA transmission and the second
SA are (unintentionally) FDMed, or the data associated with the
first SA transmission is transmitted on the same timing or the
ahead timing of the second SA transmission timing.
[0516] Accordingly, in order to solve such a situation, a method of
transmitting the second SA may be considered on the timing
immediately next to the timing (or subframe) when the last data
(re)transmission is completed associated with the first SA or on
the timing departing as much as a predetermined offset.
[0517] For example, FIG. 20c shows the case that two data 2012
(re)transmission associated with the first SA 2011 are completed,
and the second SA 2013 is transmitted on the timing departing as
much as 0 TTI offset.
[0518] The size of the predetermined offset may be indicated
through RRC signaling, and the like, or predefined, or indicated
through a physical channel (e.g., DCI).
[0519] Method 2: Application of T-RPT Pattern After a Predetermined
Timing Gap from DCI Transmission Timing
[0520] Different from method 1, method 2 relates to a method for
applying T-RPT pattern after a predetermined timing gap from the
DCI transmission timing, not the SA transmission timing.
[0521] FIG. 21 illustrates another method for determining a
transmission timing of data using T-RPT pattern proposed in the
present disclosure.
[0522] As shown in FIG. 21a, an eNB transmits DCI to a transmission
UE on subframe (SF) #n, and the transmission UE transmits data to a
reception UE by applying the T-PRT pattern on SF #(n+m) (e.g.,
m=4).
[0523] Here, the m value may be indicated through RRC signaling,
and the like, or predefined, or forwarded or transmitted to the UE
through a DCI field (e.g. T-RPT offset field).
[0524] FIG. 21a shows the case that T-RPT pattern is `00101011` and
m=4.
[0525] In FIG. 21a, the timing gap k (k=5, 6, . . . ) between DCI
and SA transmission timings may be indicated to a UE through RRC
signaling, or predefined, or forwarded through a DCI field (e.g.
T-RPT offset field).
[0526] Here, in the case that the m value corresponding to the
T-RPT timing gap is identical to the k value defined in the method
1 described above, method 1 and method 2 operate in the same
manner, that is, data is (re)transmitted on the same timing.
[0527] FIG. 21b illustrates another method for determining a
transmission timing of data using T-RPT pattern proposed in the
present disclosure.
[0528] Particularly, FIG. 21b shows the case that data is
transmitted by applying the T-RPT pattern on the timing departing
from k subframe from DCI transmission timing.
[0529] Here, k corresponds to 6.
[0530] In the case that the timing of transmitting data by applying
the T-RPT pattern is defined as the timing departing as much as k'
subframe from the SA transmission timing, k' corresponds to 2.
[0531] However, in some cases, a case may occur that (the first) SA
is transmitted on timing later than (the first or the later) data
transmission timing.
[0532] Accordingly, in order to prevent it, as shown in FIG. 22,
the first bit 2210 having `1` value for the first time in the T-RPT
pattern is synchronized with the SA transmission timing (SF #n+6,
2220). In this case, the SA and (the first) data may be transmitted
with being FDMed.
[0533] That is, FIG. 22 illustrates another method for determining
a transmission timing of data using T-RPT pattern proposed in the
present disclosure.
[0534] In addition, it is defined that the remaining bits of the
T-RPT pattern corresponds to (re)transmission timing of data.
[0535] Here, the remaining bits of the T-RPT pattern represent the
bits after the first bit having `1` value for the first time in the
T-PRT pattern.
[0536] That is, in the case that total x bits having `1` value are
existed in the T-RPT pattern, 1 bit among the total x bits
indicates SA transmission, and the remaining (x-1) bit(s) indicates
(re)transmission of data. In this case, it means that data is
(re)transmitted (x-1) times.
Second Embodiment: Not Using T-RPT Field
[0537] The second embodiment relates to a method of using another
field, not using the T-RPT field included in the DCI of Sidelink
communication for the DCI of V2X Sidelink communication.
[0538] The second embodiment may be more efficient than the first
embodiment in the following reasons.
[0539] First, since it is required to reduce a size of the DCI in
V2X Sidelink communication (Mode 3 and Mode 4), it is preferable to
define a new field having a bit number smaller than that of the
T-RPT field using 7 bits in the existing Sidelink
communication.
[0540] The reason is because there is not so such data transmission
amount for V2X Sidelink communication and a problem that resource
is wasted may occur in the case that resource is allocated using
the existing T-RPT.
[0541] In addition, since mobility is added when a UE drives in
fast speed in the V2X Sidelink communication, in the case that
resource is allocated in the existing T-RPT pattern method, the V2X
Sidelink communication may not be properly performed.
[0542] In the case that several elements constructing T-RPT, for
example, a number of repetition transmissions or repeatedly
transmitted pattern is limited to a predetermined number, all T-RPT
patterns may not be required. That is, this may mean that resource
flexibility is not so great.
[0543] Accordingly, in this case, a method of newly defining and
using other fields (e.g., other indicators) performing the same
operation may be considered than using the T-RPT.
[0544] As described above, when the indicators other than the T-RPT
field are used, the transmission pattern of the data can be
represented with a smaller number of bits than using the T-RPT
field (7 bits).
[0545] For example, in the case that retransmission data is
transmitted in a consecutive TTI or with a fixed/uniform (same
interval) interval, the T-RPT pattern described above is not
required to be used.
[0546] As such, the fixed/uniform (same interval) interval of
timing offset may be predefined, indicated through RRC signaling in
the case of being variable, or indicated through a part of fields
of the DCI.
[0547] The T-RPT pattern defined in LTE Rel-12 is defined to
perform all data retransmissions within 8 TTIs, basically.
[0548] However, even in the case that it is not available to
perform all data retransmissions within 8 TTIs, it may not be
proper to use the T-RPT pattern described above.
[0549] As an example of this, in order for all UEs to have
(re)transmission patterns which are orthogonal with each other in
time domain, it needs to be more widely spread on time domain.
[0550] However, in the case that a range that UEs may (re)transmit
in time domain is limited, a probability that collision between
transmission data occurs (i.e., transmitted in the same TTI)
becomes high.
[0551] Accordingly, it may not be proper to use the T-RPT pattern
in such a case.
[0552] Therefore, hereinafter, a method for (re)transmitting data
using a time offset related indicator, not the T-RPT pattern, is
described in detail.
[0553] That is, in the case that it is not available to use the
existing T-RPT, new time offset related indicators may be defined
which may perform the same or similar operation (or function) as
the T-RPT.
[0554] The time offset related indicator is information indicating
a timing gap or an offset between an initial data transmission and
retransmission data.
[0555] In addition, the time offset related indicator may also be
interpreted as information indicating a timing gap between
data.
[0556] At this time, types of the information that may be indicated
through the existing T-RPT may include (1) number of repetition
transmissions, (2) a timing gap between a data transmission and
(the next) data transmission (e.g., retransmission), and the
like.
[0557] In the case of not using the T-RPT, a particular method for
indicating information of (1) and (2) is required, which is
described below.
[0558] In section (2), the data transmission may mean an initial
transmission, and (the next) data transmission may mean a
retransmission
[0559] In addition, unless the case that DCI is transmitted in
every (data) (re)transmission, in addition to information of (1)
and (2), the following information is also required to be
determined.
[0560] Further, in the case that the following information does not
use the T-RPT similarly, a method of indicating it to a UE may be
required. [0561] Timing gap between SA transmission and
(associated) data transmission [0562] Timing gap between SA
transmission and (the next) SA transmission
[0563] Furthermore, in addition to the method of indicating a
time-frequency index on which SA is to be transmitted through the
existing SA resource (or resource for PSCCH), a time resource and a
frequency resource of SA may be divided and indicated.
[0564] In this case, a method of determining information such as SA
(initial) transmitting timing may also be required.
[0565] Then, a method for configuring or indicating time resource
information representing a time resource for data (re)transmission
or a specific form of the time resource, not using the T-RPT
pattern, will be described.
[0566] Here, the time resource information may include indicators
related to a timing offset.
[0567] That is, in the case that the T-RPT described in the first
embodiment is not used for data (re)transmission in the V2X
Sidelink communication, information needs to be configured or
indicated, such as (1) number of repetition transmissions, (2) SA
(initial) transmission timing, (3) a timing gap between SA
transmission and (associated) data transmission, (4) a timing gap
between data transmission and (the next) data transmission, and the
like. At least one of (1) to (4) may be included in the time
resource information.
[0568] In the case that the T-RPT is not used, a method for
indicating or configuring each of the information of (1) to (4)
will be described in detail.
[0569] First, the number of repetition transmissions is
described.
[0570] The number of repetition transmissions may represent a count
of data being repeated or retransmitted.
[0571] In the case that the T-RPT is used, the information for data
number of repetition transmissions is implicitly mapped in the
T-RPT.
[0572] However, in the case that the T-RPT is not used, the number
of repetition transmissions of data may be indicated or configured
by using the message set of Table 3 described above.
[0573] In the case that the message set is not included in the DCI
or not signaled to a UE, the number of repetition transmissions may
be indicated through RRC signaling or a part of bits of the DCI may
be used for the use of informing the number of repetition
transmissions.
[0574] Here, the information or the field indicating the number of
repetition transmissions may be represented as N_rpt field, for
example.
[0575] Next, SA (initial) transmission timing is described.
[0576] The SA (initial) transmission timing may be preferred to use
a method of indicating or determining how much degree of offset is
departed with reference to a specific timing (as a reference)
rather than indicating a specific absolute value of a timing when
SA is transmitted.
[0577] For example, in the case that an eNB transmits the DCI to a
transmission UE on n.sup.th subframe (SF #n), it may be defined
that the associated SA is transmitted on n+4.sup.th subframe (SF
#n+4) or the first Sidelink subframe generated after the SF
#n+4.
[0578] The Sidelink subframe means a subframe on which the SA or
data can be transmitted, and may be represented as Sidelink Control
(SC) period.
[0579] The expression `A and/or B` used in the present disclosure
may be identically interpreted as the meaning of `at least one of A
or B`.
[0580] As such, in the case that SA transmission timing is defined,
an eNB may indicate only the frequency resource allocation
information for the SA transmission to a UE.
[0581] Subsequently, the timing gap between SA transmission and
(associated) data transmission is described.
[0582] When a specific message is generated (from a specific UE),
until the timing when a reception UE receives the generated
specific message, a latency time occurs (in physical layer)
including 1) timing gap between the message generation time and the
DCI transmission time, 2) timing gap between the DCI transmission
time and the SA transmission time, and 3) timing gap between the SA
transmission time and the Data transmission time.
[0583] It needs to configure a timing gap between the data
transmissions such that the summation of the timing gaps of
sections 1) to 3) becomes not to great considering latency
requirements for the message transmission.
[0584] For example, assuming that each of the timing gap between
the DCI transmission time and the SA transmission time and the
timing gap between the SA transmission time and the Data
transmission time is 4 TTIs, there exists latency time of 8 TTIs
already owing to the two timing gaps.
[0585] Accordingly, it is required to define or configure such that
the timing gaps between the SA transmission time and the Data
transmission time does not have too great value.
[0586] In other words, this may mean that a range of fluctuation of
the timing gap is not too great.
[0587] Accordingly, the following two methods (method 1 and method
2) may be considered such that the timing gaps between the SA
transmission time and the Data transmission time does not have too
great value.
[0588] (Method 1)
[0589] First, method 1 uses the timing gap from the SA transmission
time to the Data transmission time as a value which is common to
all UEs and a predefined fixed value.
[0590] The fact that the range of fluctuation of the corresponding
timing gap (from the SA transmission time to the Data transmission
time) is not too great may be interpreted that it does not have a
significant meaning to configure the corresponding timing gap value
in UE-specific manner.
[0591] Accordingly, it may be defined such that all UEs use a
predefined fixed value.
[0592] (Method 2)
[0593] Method 2 uses the timing gap from the SA transmission time
to the Data transmission time in UE-specific manner.
[0594] As described above, method 2 may be used for the case that
it is required to distinguish UEs using UE-specific values or the
case that it is required to allocate data resource to be flexible
to the maximum.
[0595] Method 2 may be divided into method {circle around (1)} and
method {circle around (2)} as below.
[0596] First, method {circle around (1)} is to indicate the timing
gap from the SA transmission time to the Data transmission time
through RRC signaling or inform using a part of bits of the
DCI.
[0597] In the case that the DCI is transmitted in every (data)
(re)transmission, this value may be designated through the
corresponding field in each DCI, and in the case that the DCI is
transmitted once for all (data) (re)transmissions, the timing gap
value may be identically applied to all (re)transmissions through
the corresponding field.
[0598] On the other hand, method {circle around (2)} uses the
timing gap from the SA transmission time to the Data transmission
time designated in the SA, not informing directly the timing gap
from the SA transmission time to the Data transmission time through
the DCI.
[0599] Whether to use the timing gap from the SA transmission time
to the Data transmission time designated in the SA, it may be
indicated or configured through 1 bit flag and the like in the
DCI.
[0600] For example, in the case that the 1 bit flag in the DCI is
configured as `1`, a transmission UE transmits data to a reception
UE with an offset as much as the timing gap designated in the
SA.
[0601] Here, the SA may designate a timing gap value for one or
more data transmissions.
[0602] More particularly, the timing gap value for the one or more
data transmissions may be determined by using the T-RPT value of
the SA.
[0603] That is, assuming that a position of each bit of the T-RPT
indicates a relative timing gap from the SA transmission time, the
fact that a specific bit(s) of the T-RPT is configured as `1` may
mean the data is transmitted on the timing departed as much as the
corresponding TTI from the SA.
[0604] In other words, the timing when `1` value is generated for
the first time (or firstly) in the T-RPT pattern may be the timing
gap between the SA and (the first or associated) data transmission
times.
[0605] For example, the timing when `1` value is generated for the
first time (or firstly) in the T-RPT pattern is on the first bit
(i.e., MSB bit), this may mean that the SA and the data are
transmitted on the same timing (or same subframe). In this case,
the SA and the data may be transmitted with being FDMed.
[0606] Alternatively, in the case that the 1 bit flag in the DCI is
`0`, it may be interpreted that the timing gap value designated in
the SA is not used.
[0607] For example, a data transmission time may be determined by
using a timing gap field indicating the timing gap from the SA
transmission time to the Data transmission time designated in the
DCI.
[0608] For another example, it may be configured that the SA and
the data may be transmitted on the same time, that is, FDMed.
[0609] That is, this may mean that the SA and the data are
transmitted on the same subframe.
[0610] In this case, the 1 bit flag in the DCI may be used as an
indicator for distinguishing FDM and TDM between the SA and the
data.
[0611] Next, a timing gap between a data transmission and (the
next) data transmission is described.
[0612] Similar to the timing gap between the SA transmission and
the (associated) data transmission, it is required to configure
such that the value becomes not too great (or a range of
fluctuation of the corresponding timing gap is not too great)
considering the latency requirement and the like of a message
transmission.
[0613] Accordingly, the same or similar method may be applied with
the scheme of designating the timing gap from the SA transmission
time to the data transmission time described above.
[0614] That is, firstly, a method may be applied by using the
corresponding value (timing gap between data transmission and (the
next) data transmission to a value which is common between UEs and
predefined fixed value.
[0615] Here, the fact that the range of fluctuation of the
corresponding value is not too great means that it does not have
significant meaning to configure it in UE-specific manner, and it
may be considered to use a predefined value commonly for all
UEs.
[0616] Secondly, a UE-specific value is used.
[0617] That is, in the case that UEs needs to be distinguished by
UE-specific value, or in the case that data resource allocation has
to be performed in flexible manner to the maximum, the UE-specific
value may be used.
[0618] Even in this case, method {circle around (1)} and method
{circle around (2)} of method 2 described above may be identically
applied.
[0619] That is, like the method {circle around (1)}, the timing gap
between data and (the next) data transmission times may be
indicated through RRC signaling or indicated by using a part of
bits of the DCI. In this case, this value may be indicated again
through the SA.
[0620] In the case that the DCI is transmitted in every (data)
(re)transmission, this value may be designated through the
corresponding field for each DCI, and in the case that the DCI is
transmitted only once for all (data) (re)transmissions, the timing
gap value may be identically applied to all (re)transmissions
through the corresponding field.
[0621] In addition, like the method {circle around (2)}, the timing
gap value between data and (the next) data transmission times is
not directly informed through the DCI, but the timing gap
indicating the timing gap from the data transmission time and (the
next) data transmission time designated in the SA may be
applied.
[0622] Further, whether the timing gap between the data
transmission time and the next data transmission time designated in
the SA may be indicated or configured through the 1 bit field in
the DCI.
[0623] For example, in the case that the 1 bit flag in the DCI is
value `1`, a transmission UE transmits (the next) data to a
reception UE with an offset as much as the timing gap designated in
the SA.
[0624] The SA may designate a timing gap value for one or more data
transmissions.
[0625] More particularly, the timing gap value between data
transmissions may be determined by using the T-RPT value of the
SA.
[0626] Alternatively, in the case that the 1 bit flag in the DCI is
`0`, it may be interpreted that the timing gap value designated in
the SA is not used.
[0627] For example, a data transmission time may be determined by
using a timing gap field between data and (the next) data
designated in the DCI.
[0628] A part or the whole of the predefined values described
above, RRC signaling and DCI fields may be selectively combined and
used.
[0629] As another embodiment, in the case that resource allocations
between dynamic scheduling and SPS scheduling is overlapped, a
method for solving it is described.
[0630] A part or the whole of the timing when data (re)transmission
of dynamic scheduling is generated and the timing when data
(re)transmission is generated by SPS (or timing when the
corresponding resource is allocated) in a specific UE aspect may be
overlapped.
[0631] In this case, in the case that different UEs transmit data
simultaneously (in the same TTI or the same subframe), problems
such as half-duplex, resource collision and interference increase
may occur.
[0632] Accordingly, a method may be required such that two types of
transmissions are not generated simultaneously.
[0633] In the case that two transmissions are generated
simultaneously, it may be defined to select one of the three
methods as below according to message type, application or use
case.
[0634] First, the first method is to follow resource allocation of
dynamic scheduling.
[0635] That is, the first method is to follow the resource
allocation of dynamic scheduling in the case that SPS transmission
period is not long (e.g., 10 ms) and/or more urgent and important
message is transmitted through dynamic scheduling.
[0636] At this time, the transmission data for dropped SPS (or of
which transmission time is missed) may be dropped as it is
according to importance or urgency, or may be allocated again in
other timing through SPS reconfiguration, scheduling request (for
SPS resource allocation).
[0637] Next, the second method is to follow the resource allocation
of SPS scheduling.
[0638] That is, the second method is to follow the SPS scheduling
method in the case that the SPS transmission period is relatively
long (e.g., 500 ms) and more urgent and importance message is
transmitted through serious transmission latency and/or SPS
scheduling once the SPS transmission is dropped.
[0639] Next, the third method is to follow a priority of the
message (or packet).
[0640] That is, the third method is to determine the way of
resource allocation according to a priority order provided for each
message (or packet) in the case that the priority may not be
determined only with dynamic scheduling or SPS scheduling scheme
simply.
[0641] In the case that the priority is the same, scheduling scheme
may be determined in random way.
[0642] FIG. 23 is a flowchart illustrating an example of a method
for transmitting and receiving data in V2X Sidelink communication
proposed in the present disclosure.
[0643] Referring to FIG. 23, a method is described for a first UE
to transmit Sidelink related data to a second UE through sidelink
in a wireless communication system supporting Vehicle-to-Everything
(V2X) communication.
[0644] First, the first UE receives, from a base station, Downlink
Control Information (DCI) including information related to a
transmission of first control information (step, S2310).
[0645] The DCI may also include information for transmission data
in addition to the information for the first control
information.
[0646] In addition, the DCI may include a part of the contents of
the first control information.
[0647] Further, the DCI may be represented as DCI format 5A in
Vehicle-to-Everything (V2X) Sidelink communication.
[0648] The first control information is information used for
scheduling data transmitted (or to be transmitted) to the second
UE, and may be information indicating resource allocation
information for data to be transmitted for selecting Sidelink
resource or scheduling.
[0649] The first control information may be represented Scheduling
Assignment (SA), Physical Sidelink Control Channel (PSCCH) and the
like.
[0650] Here, the first UE may mean a transmission UE, and the
second UE may mean a reception UE.
[0651] In addition, the DCI is transmitted in subframe #n, and the
first control information may be transmitted in subframe #n+k or in
a specific sidelink subframe generated after the subframe #n+k.
[0652] The k may be 4.
[0653] Here, the specific side link subframe may be the first side
link subframe (s) occurring after the (n+k) th subframe.
[0654] Here, the specific Sidelink subframe may be Sidelink
subframe(s) included in Sidelink period firstly usable which is
started after subframe #n+k.
[0655] The Sidelink period may be represented as SC period.
[0656] In addition, the DCI may include second control information
indicating a timing gap between the first data transmission and the
second data transmission, and may include the information mentioned
in the second embodiment described above.
[0657] The second control information may indicate a timing gap
field,
[0658] and included in the first control information.
[0659] Later, the first UE transmits, to the second UE, the first
control information based on the received DCI (step, S2320).
[0660] Later, the first UE transmits, to the second UE, one or more
data through the sidelink (step, S2330).
[0661] The first control information and the one or more data may
be transmitted on an identical timing, and the identical timing may
mean an identical subframe.
[0662] Further, the first data transmission may mean an initial
transmission of data, and the second data transmission may mean a
retransmission of data.
[0663] Overview of Devices to Which the Present Invention Can be
Applied
[0664] FIG. 24 illustrates a block diagram of a wireless
communication device to which the methods proposed in the present
disclosure may be applied.
[0665] Referring to FIG. 24, a wireless communication system
includes a base station (or eNB) 2410 and a plurality of terminals
(or UEs) 2420 located within coverage of the eNB 2410.
[0666] The eNB 2410 includes a processor 2411, a memory 2412, and a
radio frequency (RF) unit 2413. The processor 2411 implements
functions, processes and/or methods proposed in FIG. 1 to FIG. 23.
Layers of radio interface protocols may be implemented by the
processor 2411. The memory 2412 may be connected to the processor
2411 to store various types of information for driving the
processor 2411. The RF unit 2413 may be connected to the processor
2411 to transmit and/or receive a wireless signal.
[0667] The UE 2420 includes a processor 2421, a memory 2422, and a
radio frequency (RF) unit 2423.
[0668] The processor 2421 implements functions, processes and/or
methods proposed in FIG. 1 to FIG. 23. Layers of radio interface
protocols may be implemented by the processor 2421. The memory 2422
may be connected to the processor 2421 to store various types of
information for driving the processor 2421. The RF unit 2423 may be
connected to the processor 2421 to transmit and/or receive a
wireless signal.
[0669] The memory 2412 or 2422 may be present within or outside of
the processor 2411 or 2421 and may be connected to the processor
2411 or 2421 through various well known units.
[0670] For example, in order to transmit and receive data between
UEs in a wireless communication system supporting V2X
communication, the UE may include a Radio Frequency (RF) unit for
transmitting and receiving a radio signal; and a processor
functionally connected to the RF unit.
[0671] Also, the eNB 2410 and/or the UE 2420 may have a single
antenna or multiple antennas.
[0672] FIG. 25 illustrates a block diagram of a wireless
communication apparatus according to an embodiment of the present
invention.
[0673] Particularly, in FIG. 25, the UE described above FIG. 24
will be exemplified in more detail.
[0674] Referring to FIG. 25, the UE includes a processor (or
digital signal processor) 2510, RF module (RF unit) 2535, power
management module 2505, antenna 2540, battery 2555, display 2515,
keypad 2520, memory 2530, Subscriber Identification Module (SIM)
card 2525 (which may be optional), speaker 2545 and microphone
2550. The UE may include a single antenna or multiple antennas.
[0675] The processor 2510 may be configured to implement the
functions, procedures and/or methods proposed by the present
invention as described in FIG. 1 to FIG. 23. Layers of a wireless
interface protocol may be implemented by the processor 2510.
[0676] The memory 2530 is connected to the processor 2510 and
stores information related to operations of the processor 2510. The
memory 2530 may be located inside or outside the processor 2510 and
may be connected to the processors 2510 through various well-known
means.
[0677] A user enters instructional information, such as a telephone
number, for example, by pushing the buttons of a keypad 2520 or by
voice activation using the microphone 2550. The microprocessor 2510
receives and processes the instructional information to perform the
appropriate function, such as to dial the telephone number.
Operational data may be retrieved from the SIM card 2525 or the
memory module 2530 to perform the function. Furthermore, the
processor 2510 may display the instructional and operational
information on the display 2515 for the user's reference and
convenience.
[0678] The RF module 2535 is connected to the processor 2510,
transmits and/or receives an RF signal. The processor 2510 issues
instructional information to the RF module 2535, to initiate
communication, for example, transmits radio signals comprising
voice communication data. The RF module 2535 comprises a receiver
and a transmitter to receive and transmit radio signals. An antenna
2540 facilitates the transmission and reception of radio signals.
Upon receiving radio signals, the RF module 2535 may forward and
convert the signals to baseband frequency for processing by the
processor 2510. The processed signals would be transformed into
audible or readable information outputted via the speaker 2545.
[0679] The aforementioned embodiments are achieved by combination
of structural elements and features of the present invention in a
predetermined manner. Each of the structural elements or features
should be considered selectively unless specified separately. Each
of the structural elements or features may be carried out without
being combined with other structural elements or features. Also,
some structural elements and/or features may be combined with one
another to constitute the embodiments of the present invention. The
order of operations described in the embodiments of the present
invention may be changed. Some structural elements or features of
one embodiment may be included in another embodiment, or may be
replaced with corresponding structural elements or features of
another embodiment. Moreover, it will be apparent that some claims
referring to specific claims may be combined with another claims
referring to the other claims other than the specific claims to
constitute the embodiment or add new claims by means of amendment
after the application is filed.
[0680] The embodiments of the present invention may be achieved by
various means, for example, hardware, firmware, software, or a
combination thereof. In a hardware configuration, the methods
according to the embodiments of the present invention may be
achieved by one or more ASICs (Application Specific Integrated
Circuits), DSPs (Digital Signal Processors), DSPDs (Digital Signal
Processing Devices), PLDs (Programmable Logic Devices), FPGAs
(Field Programmable Gate Arrays), processors, controllers,
microcontrollers, microprocessors, etc.
[0681] In a firmware or software configuration, the embodiments of
the present invention may be implemented in the form of a module, a
procedure, a function, etc. Software code may be stored in the
memory and executed by the processor. The memory may be located at
the interior or exterior of the processor and may transmit data to
and receive data from the processor via various known means.
[0682] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention
without departing from the spirit or scope of the inventions. Thus,
it is intended that the present invention covers the modifications
and variations of this invention provided they come
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