U.S. patent application number 17/746621 was filed with the patent office on 2022-09-01 for method for d2d signal transmission in wireless communication system, and terminal using same.
The applicant listed for this patent is LG Electronics Inc.. Invention is credited to Seungmin Lee, Hanbyul Seo, Yunjung Yi.
Application Number | 20220278884 17/746621 |
Document ID | / |
Family ID | 1000006337075 |
Filed Date | 2022-09-01 |
United States Patent
Application |
20220278884 |
Kind Code |
A1 |
Lee; Seungmin ; et
al. |
September 1, 2022 |
METHOD FOR D2D SIGNAL TRANSMISSION IN WIRELESS COMMUNICATION
SYSTEM, AND TERMINAL USING SAME
Abstract
Provided is a method for device-to-device (D2D) signal
transmission performed by a terminal in a wireless communication
system, and a terminal device using the method. The method is
characterized by: receiving measurement carrier (MEA_CARRIER)
indication information which indicates a single downlink carrier to
be used in downlink measurement and synchronization for D2D
operation; and using, for the downlink measurement and
synchronization for D2D operation, the single downlink carrier
indicated by the measurement carrier (MEA_CARRIER) indication
information.
Inventors: |
Lee; Seungmin; (Seoul,
KR) ; Seo; Hanbyul; (Seoul, KR) ; Yi;
Yunjung; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LG Electronics Inc. |
Seoul |
|
KR |
|
|
Family ID: |
1000006337075 |
Appl. No.: |
17/746621 |
Filed: |
May 17, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16404904 |
May 7, 2019 |
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17746621 |
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15541101 |
Jun 30, 2017 |
10320600 |
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PCT/KR2016/000020 |
Jan 4, 2016 |
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16404904 |
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62099213 |
Jan 2, 2015 |
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62103503 |
Jan 14, 2015 |
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62151415 |
Apr 23, 2015 |
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62190754 |
Jul 10, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 56/00 20130101;
H04W 76/14 20180201; H04W 76/27 20180201; H04W 8/005 20130101; H04L
5/0037 20130101; H04L 5/001 20130101; H04L 27/2657 20130101; H04L
5/0048 20130101; H04W 56/001 20130101; H04W 72/0453 20130101; H04W
4/70 20180201; H04W 72/04 20130101; H04W 56/002 20130101; H04L
27/2655 20130101; H04L 5/14 20130101; H04W 72/0406 20130101; H04L
5/0091 20130101; H04W 8/00 20130101 |
International
Class: |
H04L 27/26 20060101
H04L027/26; H04L 5/00 20060101 H04L005/00; H04W 56/00 20060101
H04W056/00; H04W 8/00 20060101 H04W008/00; H04W 72/04 20060101
H04W072/04; H04W 76/14 20060101 H04W076/14; H04W 76/27 20060101
H04W076/27 |
Claims
1-14. (canceled)
15. A method for a relay user equipment (UE) to communicate with a
remote UE in a wireless communication system, the method
comprising: establishing a connection with the remote UE which is
in radio resource control (RRC) idle state related to a base
station; receiving system information from the base station; and
transmitting the system information to the remote UE.
16. The method of claim 15, wherein the system information is
related to a sidelink communication between the relay UE and the
remote UE.
17. The method of claim 15, wherein the relay UE is in RRC
connected state.
18. The method of claim 15, wherein the remote UE is located out of
a coverage of the base station.
19. A relay user equipment (UE) comprising: a transceiver for
transmitting and receiving a radio signal; and a processor coupled
to the transceiver, wherein the processor is configured to:
establish a connection with a remote UE which is in radio resource
control (RRC) idle state related to a base station; receive system
information from the base station; and transmit the system
information to the remote UE.
20. The relay UE of claim 19, wherein the system information is
related to a sidelink communication between the relay UE and the
remote UE.
21. The relay UE of claim 19, wherein the relay UE is in RRC
connected state.
22. The relay UE of claim 19, wherein the remote UE is located out
of a coverage of the base station.
23. A processor for a wireless communication device in a wireless
communication system, wherein the processor controls the wireless
communication device configured to: establish a connection with a
remote UE which is in radio resource control (RRC) idle state
related to a base station; receive system information from the base
station; and transmit the system information to the remote UE.
24. The processor of claim 23, wherein the system information is
related to a sidelink communication between the relay UE and the
remote UE.
25. The processor of claim 23, wherein the relay UE is in RRC
connected state.
26. The processor of claim 23, wherein the remote UE is located out
of a coverage of the base station.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to wireless communication, and
more particularly, to a method for transmitting a D2D
(device-to-device) signal by a user device in a wireless
communication system and the user device using the method.
Related Art
[0002] In International Telecommunication Union Radio communication
sector (ITU-R), a standardization task for International Mobile
Telecommunication (IMT)-Advanced, that is, the next-generation
mobile communication system since the third generation, is in
progress. IMT-Advanced sets its goal to support Internet Protocol
(IP)-based multimedia services at a data transfer rate of 1 Gbps in
the stop and slow-speed moving state and of 100 Mbps in the
fast-speed moving state.
[0003] For example, 3.sup.rd Generation Partnership Project (3GPP)
is a system standard to satisfy the requirements of IMT-Advanced
and is preparing for LTE-Advanced improved from Long Term Evolution
(LTE) based on Orthogonal Frequency Division Multiple Access
(OFDMA)/Single Carrier-Frequency Division Multiple Access (SC-FDMA)
transmission schemes. LTE-Advanced is one of strong candidates for
IMT-Advanced.
[0004] There is a growing interest in a Device-to-Device (D22)
technology in which devices perform direct communication. In
particular, D2D has been in the spotlight as a communication
technology for a public safety network. A commercial communication
network is rapidly changing to LTE, but the current public safety
network is basically based on the 2G technology in terms of a
collision problem with existing communication standards and a cost.
Such a technology gap and a need for improved services are leading
to efforts to improve the public safety network.
[0005] The public safety network has higher service requirements
(reliability and security) than the commercial communication
network. In particular, if coverage of cellular communication is
not affected or available, the public safety network also requires
direct communication between devices, that is, D2D operation.
[0006] D2D operation may have various advantages in that it is
communication between devices in proximity. For example, D2D UE has
a high transfer rate and a low delay and may perform data
communication. Furthermore, in D2D operation, traffic concentrated
on a base station can be distributed. If D2D UE plays the role of a
relay, it may also play the role of extending coverage of a base
station.
[0007] Meanwhile, a UE may have a radio resource control (RRC)
connection with a network through a specific carrier wave. In this
case, the specific carrier may be referred to as a primary carrier.
Conventionally, the UE is assumed to perform the D2D operation only
using the primary carrier wave. However, currently, it is also
considered to perform the D2D operation using a carrier wave other
than the primary carrier wave, and the serving cell for the UE is
not present using the other carrier wave. In this case, it is not
clear how to perform downlink measurement or synchronization
necessary for the UE to perform the D2D operation, in particular,
the D2D signal transmission.
SUMMARY OF THE INVENTION
[0008] The present invention is to provide a method for
transmitting a D2D (device-to-device) signal by a user device in a
wireless communication system and the user device using the
method.
[0009] In one aspect, provided is a method for transmitting a
device-to-device (D2D) signal by a user device in a wireless
communication system. The method includes receiving a measurement
carrier (MEA_CARRIER) indication information indicating one
downlink carrier used for downlink measurement and synchronization
for D2D operation using one downlink carrier indicated by the
measurement carrier (MEA_CARRIER) indication information to perform
downlink measurement and synchronization for the D2D operation.
[0010] The D2D operation may be a transmission of a D2D discovery
signal.
[0011] The D2D discovery signal may be transmitted via a
non-primary carrier rather than a primary carrier.
[0012] If there is an active serving cell for the user device, the
serving cell using a non-primary carrier rather than a primary
carrier for transmission of the D2D discovery signal, the activated
serving cell may be used to perform downlink measurement and
synchronization for the D2D operation.
[0013] If there is not an active serving cell for the user device,
the serving cell using a non-primary carrier rather than a primary
carrier for transmission of the D2D discovery signal, said one
downlink carrier indicated by the measurement carrier (MEA_CARRIER)
indication information may be used to perform downlink measurement
and synchronization for the D2D operation.
[0014] The one downlink carrier may be a carrier linked to the
non-primary carrier rather than the primary carrier via system
information.
[0015] The one downlink carrier may be a carrier not linked to the
non-primary carrier rather than the primary carrier via system
information.
[0016] In another aspect, provided is a user equipment. The user
equipment includes an RF (Radio Frequency) unit for transmitting
and receiving a radio signal and a processor coupled to the RF
unit. The processor is configured to receive a measurement carrier
(MEA_CARRIER) indication information indicating one downlink
carrier used for downlink measurement and synchronization for D2D
operation and to use said one downlink carrier indicated by the
measurement carrier (MEA_CARRIER) indication information to perform
downlink measurement and synchronization for the D2D operation.
[0017] The UE may transmit the D2D signal on a carrier other than
the primary carrier having the RRC connection with the network.
Downlink measurement and synchronization may be required to
transmit the D2D signal. In this connection, in one example, the UE
may not have hardware to measure the other carrier. In this case,
according to the prior art, it is unclear how to perform downlink
measurement and synchronization, which may cause problems in D2D
signal transmission. The present invention can solve the problem by
signaling, by the serving cell, the downlink carrier used for
downlink measurement and synchronization for D2D signal
transmission to the UE in the above case.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 shows a wireless communication system to which the
present invention is applied.
[0019] FIG. 2 is a diagram showing a wireless protocol architecture
for a user plane.
[0020] FIG. 3 is a diagram showing a wireless protocol architecture
for a control plane.
[0021] FIG. 4 shows a basic structure for ProSe.
[0022] FIG. 5 shows the deployment examples of types of UE
performing ProSe direct communication and cell coverage.
[0023] FIG. 6 is an embodiment of a ProSe discovery process.
[0024] FIG. 7 is another embodiment of a ProSe discovery
process.
[0025] FIG. 8 shows an example of the UE providing the relay
functionality.
[0026] FIG. 9 shows DL CARRIER #X, UL CARRIER #X, and CARRIER #Y
set for DRUE #N.
[0027] FIG. 10 illustrates a specific method using the example #4
above.
[0028] FIG. 11 illustrates a method of transmitting a D2D discovery
signal by the user device according to an embodiment of the present
invention.
[0029] FIG. 12 illustrates a situation in which the user device
performs a D2D operation.
[0030] FIG. 13 is a method for performing the D2D operation by the
user device when Rule #A-2 is applied.
[0031] FIG. 14 illustrates another situation in which the user
device performs D2D operation.
[0032] FIG. 15 is a block diagram illustrating the user device in
which an embodiment of the present invention is implemented.
DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0033] FIG. 1 shows a wireless communication system.
[0034] The wireless communication system may be referred to as an
Evolved-UMTS Terrestrial Radio Access Network (E-UTRAN) or a Long
Term Evolution (LTE)/LTE-A system, for example.
[0035] The E-UTRAN includes at least one base station (BS) 20 which
provides a control plane and a user plane to a user equipment (UE)
10. The UE 10 may be fixed or mobile, and may be referred to as
another terminology, such as a mobile station (MS), a user terminal
(UT), a subscriber station (SS), a mobile terminal (MT), a wireless
device, etc. The BS 20 is generally a fixed station that
communicates with the UE 10 and may be referred to as another
terminology, such as an evolved node-B (eNB), a base transceiver
system (BTS), an access point, etc.
[0036] The BSs 20 are interconnected by means of an X2 interface.
The BSs 20 are also connected by means of an S1 interface to an
evolved packet core (EPC) 30, more specifically, to a mobility
management entity (MME) through S1-MME and to a serving gateway
(S-GW) through S1-U.
[0037] The EPC 30 includes an MME, an S-GW, and a packet data
network-gateway (P-GW). The MME has access information of the UE or
capability information of the UE, and such information is generally
used for mobility management of the UE. The S-GW is a gateway
having an E-UTRAN as an end point. The P-GW is a gateway having a
PDN as an end point.
[0038] Layers of a radio interface protocol between the UE and the
network can be classified into a first layer (L1), a second layer
(L2), and a third layer (L3) based on the lower three layers of the
open system interconnection (OSI) model that is well-known in the
communication system. Among them, a physical (PHY) layer belonging
to the first layer provides an information transfer service by
using a physical channel, and a radio resource control (RRC) layer
belonging to the third layer serves to control a radio resource
between the UE and the network. For this, the RRC layer exchanges
an RRC message between the UE and the BS.
[0039] FIG. 2 is a diagram showing a wireless protocol architecture
for a user plane. FIG. 3 is a diagram showing a wireless protocol
architecture for a control plane. The user plane is a protocol
stack for user data transmission. The control plane is a protocol
stack for control signal transmission.
[0040] Referring to FIGS. 2 and 3, a PHY layer provides an upper
layer with an information transfer service through a physical
channel. The PHY layer is connected to a medium access control
(MAC) layer which is an upper layer of the PHY layer through a
transport channel. Data is transferred between the MAC layer and
the PHY layer through the transport channel. The transport channel
is classified according to how and with what characteristics data
is transferred through a radio interface.
[0041] Data is moved between different PHY layers, that is, the PHY
layers of a transmitter and a receiver, through a physical channel.
The physical channel may be modulated according to an Orthogonal
Frequency Division Multiplexing (OFDM) scheme, and use the time and
frequency as radio resources.
[0042] The functions of the MAC layer include mapping between a
logical channel and a transport channel and multiplexing and
demultiplexing to a transport block that is provided through a
physical channel on the transport channel of a MAC Service Data
Unit (SDU) that belongs to a logical channel. The MAC layer
provides service to a Radio Link Control (RLC) layer through the
logical channel.
[0043] The functions of the RLC layer include the concatenation,
segmentation, and reassembly of an RLC SDU. In order to guarantee
various types of Quality of Service (QoS) required by a Radio
Bearer (RB), the RLC layer provides three types of operation mode:
Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged
Mode (AM). AM RLC provides error correction through an Automatic
Repeat Request (ARQ).
[0044] The RRC layer is defined only on the control plane. The RRC
layer is related to the configuration, reconfiguration, and release
of radio bearers, and is responsible for control of logical
channels, transport channels, and PHY channels. An RB means a
logical route that is provided by the first layer (PHY layer) and
the second layers (MAC layer, the RLC layer, and the PDCP layer) in
order to transfer data between UE and a network.
[0045] The function of a Packet Data Convergence Protocol (PDCP)
layer on the user plane includes the transfer of user data and
header compression and ciphering. The function of the PDCP layer on
the user plane further includes the transfer and
encryption/integrity protection of control plane data.
[0046] What an RB is configured means a process of defining the
characteristics of a wireless protocol layer and channels in order
to provide specific service and configuring each detailed parameter
and operating method. An RB can be divided into two types of a
Signaling RB (SRB) and a Data RB (DRB). The SRB is used as a
passage through which an RRC message is transmitted on the control
plane, and the DRB is used as a passage through which user data is
transmitted on the user plane.
[0047] If RRC connection is established between the RRC layer of UE
and the RRC layer of an E-UTRAN, the UE is in the RRC connected
state. If not, the UE is in the RRC idle state.
[0048] A downlink transport channel through which data is
transmitted from a network to UE includes a broadcast channel (BCH)
through which system information is transmitted and a downlink
shared channel (SCH) through which user traffic or control messages
are transmitted. Traffic or a control message for downlink
multicast or broadcast service may be transmitted through the
downlink SCH, or may be transmitted through an additional downlink
multicast channel (MCH). Meanwhile, an uplink transport channel
through which data is transmitted from UE to a network includes a
random access channel (RACH) through which an initial control
message is transmitted and an uplink shared channel (SCH) through
which user traffic or control messages are transmitted.
[0049] Logical channels that are placed over the transport channel
and that are mapped to the transport channel include a broadcast
control channel (BCCH), a paging control channel (PCCH), a common
control channel (CCCH), a multicast control channel (MCCH), and a
multicast traffic channel (MTCH).
[0050] The physical channel includes several OFDM symbols in the
time domain and several subcarriers in the frequency domain One
subframe includes a plurality of OFDM symbols in the time domain.
An RB is a resources allocation unit, and includes a plurality of
OFDM symbols and a plurality of subcarriers. Furthermore, each
subframe may use specific subcarriers of specific OFDM symbols
(e.g., the first OFDM symbol) of the corresponding subframe for a
physical downlink control channel (PDCCH), that is, an L1/L2
control channel. A Transmission Time Interval (TTI) is a unit time
for subframe transmission.
[0051] The RRC state means whether or not the RRC layer of UE is
logically connected to the RRC layer of the E-UTRAN. A case where
the RRC layer of UE is logically connected to the RRC layer of the
E-UTRAN is referred to as an RRC connected state. A case where the
RRC layer of UE is not logically connected to the RRC layer of the
E-UTRAN is referred to as an RRC idle state. The E-UTRAN may check
the existence of corresponding UE in the RRC connected state in
each cell because the UE has RRC connection, so the UE may be
effectively controlled. In contrast, the E-UTRAN is unable to check
UE in the RRC idle state, and a Core Network (CN) manages UE in the
RRC idle state in each tracking area, that is, the unit of an area
greater than a cell. That is, the existence or non-existence of UE
in the RRC idle state is checked only for each large area.
Accordingly, the UE needs to shift to the RRC connected state in
order to be provided with common mobile communication service, such
as voice or data.
[0052] When a user first powers UE, the UE first searches for a
proper cell and remains in the RRC idle state in the corresponding
cell. The UE in the RRC idle state establishes RRC connection with
an E-UTRAN through an RRC connection procedure when it is necessary
to set up the RRC connection, and shifts to the RRC connected
state. A case where UE in the RRC idle state needs to set up RRC
connection includes several cases. For example, the cases may
include a need to send uplink data for a reason, such as a call
attempt by a user, and to send a response message as a response to
a paging message received from an E-UTRAN.
[0053] A Non-Access Stratum (NAS) layer placed over the RRC layer
performs functions, such as session management and mobility
management.
[0054] In the NAS layer, in order to manage the mobility of UE, two
types of states: EPS Mobility Management-REGISTERED
(EMM-REGISTERED) and EMM-DEREGISTERED are defined. The two states
are applied to UE and the MME. UE is initially in the
EMM-DEREGISTERED state. In order to access a network, the UE
performs a process of registering it with the corresponding network
through an initial attach procedure. If the attach procedure is
successfully performed, the UE and the MME become the
EMM-REGISTERED state.
[0055] In order to manage signaling connection between UE and the
EPC, two types of states: an EPS Connection Management (ECM)-IDLE
state and an ECM-CONNECTED state are defined. The two states are
applied to UE and the MME. When the UE in the ECM-IDLE state
establishes RRC connection with the E-UTRAN, the UE becomes the
ECM-CONNECTED state. The MME in the ECM-IDLE state becomes the
ECM-CONNECTED state when it establishes S1 connection with the
E-UTRAN. When the UE is in the ECM-IDLE state, the E-UTRAN does not
have information about the context of the UE. Accordingly, the UE
in the ECM-IDLE state performs procedures related to UE-based
mobility, such as cell selection or cell reselection, without a
need to receive a command from a network. In contrast, when the UE
is in the ECM-CONNECTED state, the mobility of the UE is managed in
response to a command from a network. If the location of the UE in
the ECM-IDLE state is different from a location known to the
network, the UE informs the network of its corresponding location
through a tracking area update procedure.
[0056] The D2D operation will now be described. In 3GPP LTE-A, the
service related to D2D operation is called proximity based service
(ProSe). Hereinafter, ProSe is equivalent to D2D operation and
ProSe may be interchanged with D2D operation. ProSe will now be
described.
[0057] The ProSe includes ProSe direction communication and ProSe
direct discovery. The ProSe direct communication is communication
performed between two or more proximate UEs. The UEs may perform
communication by using a protocol of a user plane. A ProSe-enabled
UE implies a UE supporting a procedure related to a requirement of
the ProSe. Unless otherwise specified, the ProSe-enabled UE
includes both of a public safety UE and a non-public safety UE. The
public safety UE is a UE supporting both of a function specified
for a public safety and a ProSe procedure, and the non-public
safety UE is a UE supporting the ProSe procedure and not supporting
the function specified for the public safety.
[0058] ProSe direct discovery is a process for discovering another
ProSe-enabled UE adjacent to ProSe-enabled UE. In this case, only
the capabilities of the two types of ProSe-enabled UE are used.
EPC-level ProSe discovery means a process for determining, by an
EPC, whether the two types of ProSe-enabled UE are in proximity and
notifying the two types of ProSe-enabled UE of the proximity.
[0059] Hereinafter, for convenience, the ProSe direct communication
may be referred to as D2D communication, and the ProSe direct
discovery may be referred to as D2D discovery.
[0060] FIG. 4 shows a basic structure for ProSe.
[0061] Referring to FIG. 4, the basic structure for ProSe includes
an E-UTRAN, an EPC, a plurality of types of UE including a ProSe
application program, a ProSe application server (a ProSe APP
server), and a ProSe function.
[0062] The EPC represents an E-UTRAN core network configuration.
The EPC may include an MME, an S-GW, a P-GW, a policy and charging
rules function (PCRF), a home subscriber server (HSS) and so
on.
[0063] The ProSe APP server is a user of a ProSe capability for
producing an application function. The ProSe APP server may
communicate with an application program within UE. The application
program within UE may use a ProSe capability for producing an
application function.
[0064] The ProSe function may include at least one of the
followings, but is not necessarily limited thereto. [0065]
Interworking via a reference point toward the 3rd party
applications [0066] Authorization and configuration of UE for
discovery and direct communication [0067] Enable the functionality
of EPC level ProSe discovery [0068] ProSe related new subscriber
data and handling of data storage, and also handling of the ProSe
identities [0069] Security related functionality [0070] Provide
control towards the EPC for policy related functionality [0071]
Provide functionality for charging (via or outside of the EPC,
e.g., offline charging)
[0072] A reference point and a reference interface in the basic
structure for ProSe are described below. [0073] PC1: a reference
point between the ProSe application program within the UE and the
ProSe application program within the ProSe APP server. This is used
to define signaling requirements in an application dimension.
[0074] PC2: a reference point between the ProSe APP server and the
ProSe function. This is used to define an interaction between the
ProSe APP server and the ProSe function. The update of application
data in the ProSe database of the ProSe function may be an example
of the interaction. [0075] PC3: a reference point between the UE
and the ProSe function. This is used to define an interaction
between the UE and the ProSe function. A configuration for ProSe
discovery and communication may be an example of the interaction.
[0076] PC4: a reference point between the EPC and the ProSe
function. This is used to define an interaction between the EPC and
the ProSe function. The interaction may illustrate the time when a
path for 1:1 communication between types of UE is set up or the
time when ProSe service for real-time session management or
mobility management is authenticated. [0077] PC5: a reference point
used for using control/user plane for discovery and communication,
relay, and 1:1 communication between types of UE. [0078] PC6: a
reference point for using a function, such as ProSe discovery,
between users belonging to different PLMNs. [0079] SGi: this may be
used to exchange application data and types of application
dimension control information.
[0080] The D2D operation may be supported both when UE is serviced
within the coverage of a network (cell) or when it is out of
coverage of the network.
[0081] FIG. 5 shows the deployment examples of types of UE
performing ProSe direct communication and cell coverage.
[0082] Referring to FIG. 5(a), types of UE A and B may be placed
outside cell coverage. Referring to FIG. 5(b), UE A may be placed
within cell coverage, and UE B may be placed outside cell coverage.
Referring to FIG. 5(c), types of UE A and B may be placed within
single cell coverage. Referring to FIG. 5(d), UE A may be placed
within coverage of a first cell, and UE B may be placed within
coverage of a second cell.
[0083] ProSe direct communication may be performed between types of
UE placed at various positions as in FIG. 5.
[0084] <Radio Resource Allocation for D2D Communication (ProSe
Direct Communication)>.
[0085] At least one of the following two modes may be used for
resource allocation for D2D communication.
[0086] 1. Mode 1
[0087] Mode 1 is mode in which resources for ProSe direct
communication are scheduled by an eNB. UE needs to be in the
RRC_CONNECTED state in order to send data in accordance with mode
1. The UE requests a transmission resource from an eNB. The eNB
performs scheduling assignment and schedules resources for sending
data. The UE may send a scheduling request to the eNB and send a
ProSe Buffer Status Report (BSR). The eNB has data to be subjected
to ProSe direct communication by the UE based on the ProSe BSR and
determines that a resource for transmission is required.
[0088] 2. Mode 2
[0089] Mode 2 is mode in which UE directly selects a resource. UE
directly selects a resource for ProSe direct communication in a
resource pool. The resource pool may be configured by a network or
may have been previously determined.
[0090] Meanwhile, if UE has a serving cell, that is, if the UE is
in the RRC_CONNECTED state with an eNB or is placed in a specific
cell in the RRC_IDLE state, the UE is considered to be placed
within coverage of the eNB.
[0091] If UE is placed outside coverage, only mode 2 may be
applied. If the UE is placed within the coverage, the UE may use
mode 1 or mode 2 depending on the configuration of an eNB.
[0092] If another exception condition is not present, only when an
eNB performs a configuration, UE may change mode from mode 1 to
mode 2 or from mode 2 to mode 1.
[0093] <D2D Discovery (ProSe Direct Discovery)>
[0094] D2D discovery refers to the procedure used in a ProSe
capable terminal discovering other ProSe capable terminals in close
proximity thereto and may be referred to as ProSe direct discovery.
The information used for ProSe direct discovery is hereinafter
referred to as discovery information.
[0095] A PC 5 interface may be used for D2D discovery. The PC 5
interface includes an MAC layer, a PHY layer, and a ProSe Protocol
layer, that is, a higher layer. The higher layer (the ProSe
Protocol) handles the permission of the announcement and monitoring
of discovery information. The contents of the discovery information
are transparent to an access stratum (AS). The ProSe Protocol
transfers only valid discovery information to the AS for
announcement. The MAC layer receives discovery information from the
higher layer (the ProSe Protocol). An IP layer is not used to send
discovery information. The MAC layer determines a resource used to
announce discovery information received from the higher layer. The
MAC layer produces an MAC protocol data unit (PDU) for carrying
discovery information and sends the MAC PDU to the physical layer.
An MAC header is not added.
[0096] In order to announce discovery information, there are two
types of resource assignment.
[0097] 1. Type 1
[0098] The type 1 is a method for assigning a resource for
announcing discovery information in a UE-not-specific manner. An
eNB provides a resource pool configuration for discovery
information announcement to types of UE. The configuration may be
broadcasted through the SIB. The configuration may be provided
through a UE-specific RRC message. Or the configuration may be
broadcasted through other than the RRC message in other layer or
may be provided by UE-specific signaling.
[0099] UE autonomously selects a resource from an indicated
resource pool and announces discovery information using the
selected resource. The UE may announce the discovery information
through a randomly selected resource during each discovery
period.
[0100] 2. Type 2
[0101] The type 2 is a method for assigning a resource for
announcing discovery information in a UE-specific manner. UE in the
RRC_CONNECTED state may request a resource for discovery signal
announcement from an eNB through an RRC signal. The eNB may
announce a resource for discovery signal announcement through an
RRC signal. A resource for discovery signal monitoring may be
assigned within a resource pool configured for types of UE.
[0102] An eNB 1) may announce a type 1 resource pool for discovery
signal announcement to UE in the RRC_IDLE state through the SIB.
Types of UE whose ProSe direct discovery has been permitted use the
type 1 resource pool for discovery information announcement in the
RRC_IDLE state. Alternatively, the eNB 2) announces that the eNB
supports ProSe direct discovery through the SIB, but may not
provide a resource for discovery information announcement. In this
case, UE needs to enter the RRC_CONNECTED state for discovery
information announcement.
[0103] An eNB may configure that UE has to use a type 1 resource
pool for discovery information announcement or has to use a type 2
resource through an RRC signal in relation to UE in the
RRC_CONNECTED state.
[0104] FIG. 6 is an embodiment of a ProSe discovery process.
[0105] Referring to FIG. 6, it is assumed that UE A and UE B have
ProSe-enabled application programs managed therein and have been
configured to have a `friend` relation between them in the
application programs, that is, a relationship in which D2D
communication may be permitted between them. Hereinafter, the UE B
may be represented as a `friend` of the UE A. The application
program may be, for example, a social networking program. `3GPP
Layers` correspond to the functions of an application program for
using ProSe discovery service, which have been defined by 3GPP.
[0106] Direct discovery between the types of UE A and B may
experience the following process.
[0107] 1. First, the UE A performs regular application layer
communication with the APP server. The communication is based on an
Application Program Interface (API).
[0108] 2. The ProSe-enabled application program of the UE A
receives a list of application layer IDs having a `friend`
relation. In general, the application layer ID may have a network
access ID form. For example, the application layer ID of the UE A
may have a form, such as "adam@example.com."
[0109] 3. The UE A requests private expressions code for the user
of the UE A and private representation code for a friend of the
user.
[0110] 4. The 3GPP layers send a representation code request to the
ProSe server.
[0111] 5. The ProSe server maps the application layer IDs, provided
by an operator or a third party APP server, to the private
representation code. For example, an application layer ID, such as
adam@example.com, may be mapped to private representation code,
such as "GTER543 #2FSJ67DFSF." Such mapping may be performed based
on parameters (e.g., a mapping algorithm, a key value and so on)
received from the APP server of a network.
[0112] 6. The ProSe server sends the types of derived
representation code to the 3GPP layers. The 3GPP layers announce
the successful reception of the types of representation code for
the requested application layer ID to the ProSe-enabled application
program. Furthermore, the 3GPP layers generate a mapping table
between the application layer ID and the types of representation
code.
[0113] 7. The ProSe-enabled application program requests the 3GPP
layers to start a discovery procedure. That is, the ProSe-enabled
application program requests the 3GPP layers to start discovery
when one of provided `friends` is placed in proximity to the UE A
and direct communication is possible. The 3GPP layers announces the
private representation code (i.e., in the above example, "GTER543
#2FSJ67DFSF", that is, the private representation code of
adam@example.com) of the UE A. This is hereinafter called
`announcement`. Mapping between the application layer ID of the
corresponding application program and the private representation
code may be known to only `friends` which have previously received
such a mapping relation, and the `friends` may perform such
mapping.
[0114] 8. It is assumed that the UE B operates the same
ProSe-enabled application program as the UE A and has executed the
aforementioned 3 to 6 steps. The 3GPP layers placed in the UE B may
execute ProSe discovery.
[0115] 9. When the UE B receives the aforementioned `announce` from
the UE A, the UE B determines whether the private representation
code included in the `announce` is known to the UE B and whether
the private representation code is mapped to the application layer
ID. As described the 8 step, since the UE B has also executed the 3
to 6 steps, it is aware of the private representation code, mapping
between the private representation code and the application layer
ID, and corresponding application program of the UE A. Accordingly,
the UE B may discover the UE A from the `announce` of the UE A. The
3GPP layers announce that adam@example.com has been discovered to
the ProSe-enabled application program within the UE B.
[0116] In FIG. 6, the discovery procedure has been described by
taking into consideration all of the types of UE A and B, the ProSe
server, the APP server and so on. From the viewpoint of the
operation between the types of UE A and B, the UE A sends (this
process may be called announcement) a signal called announcement,
and the UE B receives the announce and discovers the UE A. That is,
from the aspect that an operation that belongs to operations
performed by types of UE and that is directly related to another UE
is only step, the discovery process of FIG. 6 may also be called a
single step discovery procedure.
[0117] FIG. 7 is another embodiment of a ProSe discovery
process.
[0118] In FIG. 7, types of UE 1 to 4 are assumed to types of UE
included in specific group communication system enablers (GCSE)
group. It is assumed that the UE 1 is a discoverer and the types of
UE 2, 3, and 4 are discoveree. UE 5 is UE not related to the
discovery process.
[0119] The UE 1 and the UE 2-4 may perform a next operation in the
discovery process.
[0120] First, the UE 1 broadcasts a target discovery request
message (may be hereinafter abbreviated as a discovery request
message or M1) in order to discover whether specific UE included in
the GCSE group is in proximity. The target discovery request
message may include the unique application program group ID or
layer-2 group ID of the specific GCSE group. Furthermore, the
target discovery request message may include the unique ID, that
is, application program private ID of the UE 1. The target
discovery request message may be received by the types of UE 2, 3,
4, and 5.
[0121] The UE 5 sends no response message. In contrast, the types
of UE 2, 3, and 4 included in the GCSE group send a target
discovery response message (may be hereinafter abbreviated as a
discovery response message or M2) as a response to the target
discovery request message. The target discovery response message
may include the unique application program private ID of UE sending
the message.
[0122] An operation between types of UE in the ProSe discovery
process described with reference to FIG. 7 is described below. The
discoverer (the UE 1) sends a target discovery request message and
receives a target discovery response message, that is, a response
to the target discovery request message. Furthermore, when the
discoveree (e.g., the UE 2) receives the target discovery request
message, it sends a target discovery response message, that is, a
response to the target discovery request message. Accordingly, each
of the types of UE performs the operation of the 2 step. In this
aspect, the ProSe discovery process of FIG. 7 may be called a
2-step discovery procedure.
[0123] In addition to the discovery procedure described in FIG. 7,
if the UE 1 (the discoverer) sends a discovery conform message (may
be hereinafter abbreviated as an M3), that is, a response to the
target discovery response message, this may be called a 3-step
discovery procedure.
[0124] Meanwhile, a UE supporting D2D operation may provide relay
functionality to another network node (e.g., another UE or a base
station).
[0125] FIG. 8 shows an example of the UE providing the relay
functionality.
[0126] Referring to FIG. 8, UE 2 153 performs a repeater function
between the base station 151 and UE 1 152. That is, the UE 2 153
may be referred to as a network node that performs a relay function
between the UE 1 152 located outside the coverage 154 of the
network and the network 151. D2D operation may be performed between
UE 1 and UE 2 152 and 153. Conventional cellular communication or
wide area network (WAN) communication may be performed between UE 2
153 and network 151. In FIG. 8, since UE 1 152 is located outside
the network coverage, it cannot communicate with network 151 if UE
2 153 does not provide the relay function therebetween.
[0127] The present invention will now be described.
[0128] The present invention proposes a method for a UE to transmit
a synchronization signal and a broadcast channel in order to
perform a D2D operation.
[0129] The UE may be a UE serving as a relay unit. In one example,
a UE 1 supporting D2D operation may perform a similar role as a
repeater between the UE 2 located outside the coverage of the
network and the network. That is, the UE 1 may receive a signal
transmitted from the network and send the signal to the UE 2
outside the coverage or may receive a signal transmitted by the UE
2 outside the coverage and transmit the signal to the network. The
D2D operation may be used between the UEs 1 and 2.
[0130] Hereinafter, the UE performing the relay communication using
the D2D operation will be referred to as `D2D UE`, or `DRUE`. DRUE
may transmit a synchronization signal and a broadcast channel when
performing relay communication using the D2D operation.
Hereinafter, the synchronization signal used for the D2D operation
will be referred to as SSS (SIDELINK SYNCHRONIZATION SIGNAL), and
the broadcast channel used for the D2D operation will be referred
to as PSBCH (PHYSICAL SIDELINK BROADCAST CHANNEL), in order to
distinguish from an existing synchronization signal and broadcast
channel.
[0131] The SSS may include at least one of a PRIMARY SIDELINK
SYNCHRONIZATION SIGNAL (PSSS) and a SECONDARY SIDELINK
SYNCHRONIZATION SIGNAL (SSSS).
[0132] Hereinafter, it is referred to as D2D communication that the
UE communicates directly with another UE using a wireless channel
(That is, in the following, the above-mentioned ProSe direct
communication and ProSe discovery are collectively referred to as
D2D communication.) The UE refers to the user device. However, a
network equipment such as the base station may be regarded as a
kind of UE when the network equipment such as the base station
transmits/receives signals according to a communication method
between the UEs.
[0133] Hereinafter, the present invention will be described with
reference to the 3GPP LTE/LTE-A system for the convenience of
description, but the scope of the system to which the present
invention is applied is not limited to the 3GPP LTE/LTE-A system
and may be extended to other systems.
[0134] An example of the PSBCH and SSS transmission
operation/method is shown in the following section 1.
[0135] <Start of Section 1>
[0136] Physical Sidelink Broadcast Channel (PSBCH).
[0137] 1. Scrambling
[0138] The block of bits b(0), . . . , b(M.sub.bit-1), where
M.sub.bit is the number of bits transmitted on the physical
sidelink broadcast channel in one subframe, shall be scrambled. The
scrambling sequence generator shall be initialised at the start of
every PSBCH subframe with c.sub.init=N.sub.ID.sup.SL.
[0139] 2. Modulation
[0140] Modulation shall be done according to Table 1 specifying the
modulation mappings applicable for the physical sidelink broadcast
channel.
TABLE-US-00001 TABLE 1 <PSBCH modulation schemes> Physical
channel Modulation schemes PSBCH QPSK
[0141] 3. Layer Mapping
[0142] Layer mapping shall be done assuming a single antenna port,
v=1.
[0143] 4. Transform Precoding
[0144] Transform precoding shall be done with M.sub.RB.sup.PUSCH
and M.sub.sc.sup.PUSCH replaced by M.sub.RB.sup.PSBCH and
M.sub.sc.sup.PSBCH, respectively.
[0145] 5. Precoding
[0146] Precoding shall be done assuming a single antenna port,
v=1.
[0147] 6. Mapping to Physical Resources
[0148] The block of complex-valued symbols z(0), . . . ,
z(M.sub.symb.sup.ap-1) shall be multiplied with the amplitude
scaling factor .beta..sub.PSBCH in order to conform to the transmit
power P PSBCH and mapped in sequence starting with z(0) to physical
resource blocks on antenna port p and assigned for transmission of
PSBCH. The mapping to resource elements (k,l) corresponding to the
physical resource blocks assigned for transmission and not used for
transmission of reference signals or synchronization signals shall
be in increasing order of first the index k, then the index l,
starting with the first slot in the subframe. Resource elements in
the last SC-FDMA symbol within a subframe should be counted in the
mapping process but not transmitted.
[0149] The PSBCH shall use the same set of resource blocks as the
synchronization signal.
[0150] 7. Sidelink Synchronization Signals (SSS)
[0151] A physical-layer sidelink synchronization identity is
represented by N.sub.ID.sup.SL.di-elect cons.{0, 1, . . . , 335},
divided into two the two sets id_net and id_oon consisting of
identities {0, 1, . . . , 167} and {168, 169, . . . , 335},
respectively.
[0152] 7.1 Primary Sidelink Synchronization Signal (PSSS)
[0153] The primary sidelink synchronization signal is transmitted
in two adjacent SC-FDMA symbols in the same subframe.
[0154] 7.1.1 Sequence Generation
[0155] Each of the two sequences d.sub.i(0), . . . , d.sub.i(61),
i=1, 2 used for the primary sidelink synchronization signal in the
two SC-FDMA symbols is given with root index u=26 if
N.sub.ID.sup.SL.ltoreq.167 and u=37 otherwise.
[0156] 7.1.2 Mapping to Resource Elements
[0157] The sequence d.sub.i(n) shall be multiplied with the
amplitude scaling factor .beta..sub.PSBCH and mapped to resource
elements on antenna port 1010 in the first slot in the subframe
according to below equation 1.
a k , l = d i ( n ) , n = 0 , , 61 .times. k = n - 3 .times. 1 + N
R .times. B S .times. L .times. N s .times. c R .times. B 2 .times.
l = { 1 , 2 normal .times. cyclic .times. prefix 0 , 1 extended
.times. cyclic .times. prefix [ Equation .times. 1 ]
##EQU00001##
[0158] 7.2 Secondary Sidelink Synchronization Signal (SSSS)
[0159] The secondary sidelink synchronization signal is transmitted
in two adjacent SC-FDMA symbols in the same subframe.
[0160] 7.2.1 Sequence Generation
[0161] Each of the two sequences d.sub.i(0), . . . , d.sub.i(61),
i=1, 2 used for the secondary sidelink synchronization signal is
given assuming subframe 0 with 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..
[0162] 7.2.2 Mapping to Resource Elements
[0163] The sequence d.sub.i(n) shall be multiplied with the
amplitude scaling factor .beta..sub.SSSS.ltoreq..beta..sub.PSBCH
and mapped to resource elements on antenna port 1010 in the second
slot in the subframe according to below equation 2.
a k , l = d i ( n ) , n = 0 , , 61 .times. k = n - 31 + N R .times.
B S .times. L .times. N s .times. c R .times. B 2 .times. l = { 4 ,
5 normal .times. cyclic .times. prefix 3 , 4 extended .times.
cyclic .times. prefix [ Equation .times. 2 ] ##EQU00002##
[0164] <End of Section 1>
[0165] Referring to Section 1, the PSBCH may be transmitted through
scrambling, modulation, layer mapping, transform precoding,
precoding, mapping to physical resources, and the like.
[0166] A block of bits b(0), . . . , b(M.sub.bit-1) is scrambled
using a scrambling sequence. Here, M.sub.bit represents the number
of bits transmitted over the PBSCH in one subframe. The scrambling
sequence used for scrambling may use a sequence generated based on
the N.sup.SL.sub.ID for each subframe transmitting the PSBCH. PSBCH
uses QPSK as modulation scheme. Layer mapping and precoding are
performed using the assumption of a single antenna port.
[0167] Next, a transmission method of the SSS will be described
with reference to Section 1 above.
[0168] The SSS may include PSSS and SSSS. PSSS may be transmitted
using two concatenated SC-FDMA symbols in the same subframe, more
specifically, the second and third SC-FDMA symbols in the first
slot (this is true of a normal CP; in an case of an extended CP, it
may be transmitted using the first and second SC-FDMA symbols of
the first slot). Two sequences, each having a length of 62 may be
used for the two SC-FDMA symbols, and a root index of the sequences
may be different between a case where the N.sup.SL.sub.ID is 167
and a case where the N.sup.SL.sub.ID is not 167. Here, the
N.sup.SL.sub.ID may be a physical-layer sidelink synchronization
identity, and may have a value from 0 to 335 or less. The
N.sup.SL.sub.ID may be divided into id_net and id_oon, where id_net
is a ID used in the coverage and id_oon is a ID used outside the
coverage. Id_net may have a value from 0 to 167, and id_oon may
have a value from 168 to 335.
[0169] SSSS may be transmitted using two concatenated SC-FDMA
symbols in the same subframe, more specifically, the fifth and
sixth SC-FDMA symbols in the second slot (this is true of a normal
CP; in an case of an extended CP, it may be transmitted using the
fourth and fifth SC-FDMA symbols of the second slot). Two
sequences, each having a length of 62 may be used for the two
SC-FDMA symbols,
[0170] For convenience of explanation, some terms and situations to
which the present invention is applied will be described.
[0171] FIG. 9 shows DL CARRIER #X, UL CARRIER #X, and CARRIER #Y
set for DRUE #N.
[0172] Referring to FIG. 9, DRUE #N is assigned `DL CARRIER #X`,
which is a downlink carrier related to WAN (wide area network
communication), and `UL CARRIER #X`, which is an uplink carrier
related to WAN (wide area network communication). Further, DRUE #N
is assigned `CARRIER #Y` related to D2D communication (or D2D relay
communication). That is, DL CARRIER #X and UL CARRIER #X are
respectively downlink and uplink carriers constituting a serving
cell of DRUE #N (or for which the serving cell of DRUE #N is
present). CARRIER #Y is a carrier used for D2D communication.
[0173] Hereinafter, this situation is assumed and explained.
[0174] In D2D communication, the D2D communication related
parameter values and the operation procedures used may vary
depending on whether the UE is in network (cell) coverage or
outside the coverage. Thus, the UE may need to perform measurements
in order to determine whether the UE is in network (cell) coverage
or outside the coverage, to perform D2D communication.
[0175] Hereinafter, based on (DL) CARRIER, measurements may be
performed in order to determine whether the UE is in network (cell)
coverage or outside the coverage, to perform D2D communication.
Further, based on (DL) CARRIER, S-CRITERION (cell selection or
reselection) may be determined. This (DL) CARRIER may be referred
to as MEA_CARRIER. Further, based on the MEA_CARRIER, D2D
communication related (downlink) measurement (e.g., (D2D
transmission) power setting related PL (Pathloss) measurement) may
be performed. Further, D2D communication related (downlink)
synchronization may be based on the MEA_CARRIER. The MEA_CARRIER
setting (or pairing) information may be communicated to the D2D UE
via predefined signaling (e.g., SIB, RRC).
[0176] In the illustrated situation, in one example, DL CARRIER #X
may be interpreted as being set to MEA_CARRIER of UL CARRIER #X
(and/or MEA_CARRIER of CARRIER #Y may be interpreted as being set
to DL CARRIER #X).
[0177] Also, the DRUE #N may be interpreted as an IN-COVERAGE D2D
UE in a (communication) coverage of a base station performing WAN
communication based on DL CARRIER #X.
[0178] In the illustrated situation, it is assumed that there is no
base station performing WAN communication based on the
corresponding CARRIER #Y. Accordingly, a D2D UE performing D2D
communication only using CARRIER #Y is regarded as `OUT-OF-COVERAGE
(D2D UE)`.
[0179] CARRIER #Y may be interpreted as CARRIER (or resource) (or
CARRIER which not assigned MEA_CARRIER) that is used only for D2D
communication (or D2D relay communication).
[0180] In addition, for convenience of explanation, in one example,
the OOC D2D UE that performs D2D RELAY communication with DRUE #N
using CARRIER #Y is referred to as `OOC D2D UE #K` In FIG. 9, UE #K
is OOC D2D UE #K. The OOC D2D UE #K may be interpreted as D2D UE as
that does not find the base station (or cell) on the DL CARRIER #X
and performs the OOC D2D communication on CARRIER #Y that has been
preconfigured. The OOC D2D UE #K may be interpreted a D2D UE which
cannot perform D2D communication in the band to which UL CARRIER #X
belongs due to RF Capability Limitation, but which is capable of
performing D2D communication only in the band to which CARRIER #Y
belongs.
[0181] Hereinafter, the proposals of the present invention may be
applied only in a limited manner to following cases: a case when
DRUE #N performs D2D communication (or D2D relay communication)
only using CARRIER #Y and/or a case when DRUE #N performs D2D
communication (or D2D relay communication) using both UL CARRIER #X
and CARRIER #Y.
[0182] Also, the proposals of the present invention allow the OOC
D2D UE #K to effectively receive the D2D Relay communication
related information (or the D2D Relay communication data) by
allowing DRUN #N to effectively transmit the SSS and/or the PSBCH
when the DRUN #N carries out the D2D Relay communication on the
CARRIER #Y. In one example, the DRUE #N may be interpreted as an
OUTBAND RELAY. Here, the OUTBAND RELAY may be defined as a repeater
in which the first link between the base station and the repeater
and the second link between the repeater and the UE are not
operated at the same frequency, or the first and second links are
sufficiently isolated in the frequency domain such that
interference is not problematic although the two links are
simultaneously activated.
[0183] The proposals of the present invention can be extended, in
one example, when DRUE #N carries out D2D communication (or D2D
relay communication) on CARRIER #Y. Alternatively, the proposals of
the present invention may be applied regardless of whether CARRIER
#Y is assigned MEA_CARRIER (or whether MEA_CARRIER of CARRIER #Y is
set to DL CARRIER #X). Otherwise, the proposals of the present
invention may be applied only a case when CARRIER #Y is assigned
MEA_CARRIER or when MEA_CARRIER of CARRIER #Y is set to DL CARRIER
#X.
[0184] In addition, in one example, DRUE #N may be interpreted to
relay DL CARRIER #X (which is MEA_CARRIER) (or UL CARRIER #X)
related (system/relay) information (or (system/relay) information
related to a base station performing WAN DL communication therewith
using DL CARRIER #X) (to OOC D2D UE #K) using CARRIER #Y. In
addition, in one example, DRUE #N may be interpreted to be in an
RRC connection state (RRC_CONNECTED) in the view of DL CARRIER #X
(which is MEA_CARRIER) (or UL CARRIER #X) or in the view of a base
station performing WAN DL communication therewith using DL CARRIER
#X.
[0185] [The present method #1] When DRUE #N transmits a D2D Relay
communication related SSS and/or PSBCH using CARRIER #Y, it may be
defined to follow some or all of the following rules.
Example #1
[0186] The ROOT SEQUENCE INDEX value for generation of the sequence
of the PSSS may be defined to use a value defined for an
IN-COVERAGE (hereinafter referred to as IC). In one example, the
PSSS ROOT SEQUENCE INDEX value for the IC may be defined as 26, and
the PSSS ROOT SEQUENCE INDEX value for the OOC may be defined as
37.
[0187] When such a rule is applied, the D2D Relay communication
related PSSS transmitted by DRUE #N using CARRIER #Y may be
regarded as the PSSS transmitted by the IC D2D UE in terms of OOC
D2D UE #K. At this time, the PSSS transmission may be configured to
be performed using IC SSS TRANSMISSION RESOURCE (or OSS SSS
TRANSMISSION RESOURCE or D2D RELAY communication related SSS
TRANSMISSION RESOURCE).
Example #2
[0188] The SIDELINK SYNCHRONIZATION IDENTITY (ID) value for
generation of the sequence of the SSSS can be defined to use a
value defined for in-coverage (IC). That is, the value of the
specific ID used for generating the sequence of the SSSS is defined
for and between the in-coverage purpose and the out-coverage
purpose. When the DRUE #N transmits the D2D Relay communication
related SSSS using the CARRIER #Y, ID for IC may be used. Here, in
one example, the SIDELINK SYNCHRONIZATION ID value for IC is
defined as {0, 1, . . . , 167} (see id_net in Section 1). The
SIDELINK SYNCHRONIZATION ID value for OOC is {168, 169, . . . ,
335} (see id_oon in Section 1).
[0189] When this rule is applied, the D2D RELAY communication
related SSSS that DRUE #N transmits using CARRIER #Y may be
regarded as the SSSS transmitted by the IC D2D UE in terms of OOC
D2D UE #K. Further, in one example, when this (example #2) is
applied, the SSSS transmission may be configured to be performed
using the IC SSS TRANSMISSION RESOURCE (or OOC SSS TRANSMISSION
RESOURCE or D2D RELAY communication related SSS TRANSMISSION
RESOURCE).
Example #3
[0190] The CONTENTS transmitted through the PSBCH includes at least
one of, in one example, DFN (D2D (SUB) FRAME NUMBER), TDD UL-DL
CONFIGURATION, IN-COVERAGE INDICATOR, SIDELINK SYSTEM BANDWIDTH and
RESERVED FIELD. Among these, if the IN-COVERAGE INDICATOR has a
specific value (in one example, `1`), it may notify that the PSBCH
is a D2D signal transmitted from the IC D2D UE. When DRUE #N may
transmit the D2D Relay communication related PSBCH using CARRIER
#Y, the DRUE #N may set the IN-COVERAGE INDICATOR to `1`. In this
case, the D2D Relay communication related PSBCH transmitted by DRUE
#N using CARRIER #Y may be regarded as the PSBCH transmitted by the
IC D2D UE in view of the OOC D2D UE #K.
[0191] In another example, by setting the RESERVED FIELD in the
CONTENTS transmitted via the PSBCH to a predefined value, the PSBCH
may be defined to be interpreted as the PSBCH transmitted by the
D2D RELAY UE (or (REL-13) IC D2D UE) in terms of OOC D2D UE #K.
[0192] Also, in one example, when this (example #3) is applied, the
PSBCH transmission may be configured to be performed using the IC
SSS TRANSMISSION RESOURCE (or OOC SSS TRANSMISSION RESOURCE or D2D
RELAY communication related SSS TRANSMISSION RESOURCE).
Example #4
[0193] Through predefined signaling, DRUE #N may be informed which
CARRIER is the MEA_CARRIER of CARRIER #Y.
[0194] In one example, if MEA_CARRIER of CARRIER #Y is set (or
signaled) to DL CARRIER #X, DRUE #N is allowed to
configure/transmit the D2D RELAY communication related SSS and/or
PSBCH transmitted using CARRIER #Y in the same manner as in IC.
Here, in one example, the corresponding SSS and/or PSBCH
transmission may be configured to be performed using the IC SSS
TRANSMISSION RESOURCE (or OSS SSS TRANSMISSION RESOURCE or D2D
RELAY communication related SSS TRANSMISSION RESOURCE).
[0195] On the other hand, if MEA_CARRIER of CARRIER #Y is not set
(or signaled) (or MEA_CARRIER of CARRIER #Y is not set (or
signaled) to DL CARRIER #X), DRUE #N is allowed to
configure/transmit the D2D RELAY communication related SSS and/or
PSBCH transmitted using CARRIER #Y in the same manner as in
OCC.
[0196] Here, in one example, the corresponding SSS and/or PSBCH
transmission may be configured to be performed using an OCC SSS
TRANSMISSION RESOURCE (or IC SSS TRANSMISSION RESOURCE or D2D RELAY
communication related SSS TRANSMISSION RESOURCE). In another
example, a transmission operation using CARRIER #Y may be
determined based on MEASUREMENT and S-CRITERION satisfaction for
MEA_CARRIER of the CARRIER #Y, as designated via the MEA_CARRIER
setting related signaling (in one example, ROOT SEQUENCE INDEX for
generating a PSSS sequence and/or SIDELINK SYNCHRONIZATION ID for
SSSS sequence generation may be determined based on determination
about whether it is IC or OCC).
[0197] FIG. 10 illustrates a specific method using the example #4
above.
[0198] Referring to FIG. 10, the user device (DRUE #N) determines
whether there is an active serving cell on a non-primary carrier
that is not a primary carrier to perform a D2D operation (S190). In
one example, suppose that the user device has an RRC connection
state with a specific base station using DL carrier #X, and UL
carrier #X, and wants to transmit a D2D discovery signal using the
carrier #Y. In this case, the user device determines whether or not
there is an activated serving cell on the carrier #Y.
[0199] If there is a serving cell activated on the non-primary
carrier, the user device uses the activated serving cell for
downlink measurement and synchronization for D2D operation
(S191).
[0200] On the other hand, if there is no serving cell activated on
the non-primary carrier, the user device uses one downlink carrier
indicated by the current serving cell (base station) for downlink
measurement and synchronization for D2D operation (S192). The one
downlink carrier may be a DL carrier (e.g., a DL carrier linked by
system information) that is one of a pair of carriers via which the
user device performs the D2D operation (e.g., D2D discovery signal
transmission) or may be a DL carrier without this limitation (that
is, a DL carrier that is not linked by system information).
[0201] FIG. 11 illustrates a method of transmitting a D2D discovery
signal by the user device according to an embodiment of the present
invention.
[0202] Referring to FIG. 11, DRUE #N transmits D2D INTEREST
information to a serving cell (base station) (S111). The D2D
INTEREST information may be information that informs the serving
cell that DRUE #N is interested in D2D operation on a particular
carrier. In one example, DRUE #N may inform the serving cell that
it is interested in transmitting a D2D discovery signal using
CARRIER #Y rather than DL CARRIER #X, and UL CARRIER #X, which are
carriers that are performing WAN communication with the serving
cell. The D2D INTEREST information may be provided separately from
the capability information of the user device (UE CAPABILITY
INFORMATION) or included in the user device capability
information.
[0203] The serving cell provides MEA_CARRIER indication information
indicating the measured carrier (MEA_CARRIER) to DRUE #N (S112). In
the above example, DRUE #N may be informed that MEA_CARRIER for
CARRIER #Y is DL CARRIER #X.
[0204] DRUE #N may measure the DL CARRIER indicated by the
MEA_CARRIER indication information and perform synchronization
based on the DL CARRIER (S113). Here, it may be assumed that there
is no active serving cell using CARRIER #Y for DRUE #N. If there is
an active serving cell using CARRIER #Y for DRUE #N, then the
activated serving cell is used for downlink measurement and
synchronization for D2D operation.
[0205] DRUE #N transmits a D2D discovery signal to UE #K based on
the downlink measurement and synchronization (S114). As an
additional example, DRUE #N may perform coverage-in/out
determination for the DL CARRIER #X, to thereby use either the D2D
parameter in coverage or the D2D parameter outside of coverage for
the D2D operation using CARRIER #Y.
Example #5
[0206] The UE may be configured to configure/transmit the D2D RELAY
communication related SSS and/or PSBCH according to some or all of
the following rules.
[0207] 1) The ROOT SEQUENCE ID for generating the sequence of PSSS
and/or the SIDELINK SYNCHRONIZATION ID for SSSS sequence generation
use what is defined for the OOC purpose, but the RESERVED FIELD in
the CONTENTS transmitted through PSBCH is set to the predefined
value (or IN-COVERAGE INDICATOR is set to 1). Thus, it may be
interpreted from the point of view of the OOC D2D UE #K that the
corresponding D2D RELAY communication related SSS and/or PSBCH is
transmitted from D2D RELAY UE or (REL-13) IC D2D UE.
[0208] As another example, the ROOT SEQUENCE ID for generating the
sequence of PSSS and/or the SIDELINK SYNCHRONIZATION ID for SSSS
sequence generation use what is defined for the IC purpose, and the
RESERVED FIELD in the CONTENTS transmitted through PSBCH is set to
the predefined value (or IN-COVERAGE INDICATOR is set to 0). Thus,
it may be interpreted from the point of view of the OOC D2D UE #K
that the corresponding D2D RELAY communication related SSS and/or
PSBCH is transmitted from D2D RELAY UE or (REL-13) IC D2D UE.
[0209] 2) The ROOT SEQUENCE ID for generating the sequence of PSSS
and/or the SIDELINK SYNCHRONIZATION ID for SSSS sequence generation
use what is defined for the IC purpose, and the IN-COVERAGE
INDICATOR in the CONTENTS transmitted through PSBCH is set to 1 (or
the RESERVED FIELD is set to the predefined value). Thus, it may be
interpreted from the point of view of the OOC D2D UE #K that the
corresponding D2D RELAY communication related SSS and/or PSBCH is
transmitted from D2D RELAY UE or (REL-13) IC D2D UE.
[0210] 3) As another example, the ROOT SEQUENCE ID for generating
the sequence of PSSS and/or the SIDELINK SYNCHRONIZATION ID for
SSSS sequence generation use what is defined for the IC (or OOC)
purpose, and the SIDELINK SYNCHRONIZATION ID (see Section 1) used
for the initialization of the PSBCH SCRAMBLING SEQUENCE GENERATOR
may be defined to use (or substitute) a pre-configured (or
signaled) D2D RELAY communication-related SIDELINK SYNCHRONIZATION
ID value.
[0211] Here, in one example, the DID Relay communication-related
SIDELINK SYNCHRONIZATION ID value may be set (or signaled) to one
of the SIDELINK SYNCHRONIZATION IDs (e.g., {168, 169, . . . , 335})
for OCC (See id_oon in Section 1) or may be set (or signaled) to
one of the SIDELINK SYNCHRONIZATION IDs for IC (e.g., {0, 1, . . .
, 167} (See id_net in Section 1).
Example #6
[0212] The SIDELINK SYNCHRONIZATION ID used in the determination of
the ROOT SEQUENCE INDEX related to the PSSS sequence generation
and/or the SIDELINK SYNCHRONIZATION ID used for generating the SSSS
sequence (see Section 1) may be configured to use (or substitute)
the SIDELINK SYNCHRONIZATION ID value (e.g., {168, 169, . . . ,
335} (see id_oon in Section 1) as preconfigured or pre-signaled for
OOC. Here, in one example, a rule may be defined to pre-signal (or
preset) SSS (and/or PSBCH) transmission related resources. When
such a rule is applied, in one example, DRUE(s) that transmits a
D2D RELAY communication related SSS (and/or PSBCH) using CARRIER #Y
may be configured to use the same SIDELINK SYNCHRONIZATION ID for
PSSS and/or SSSS sequence generation and/or PSBCH SCRAMBLING
SEQUENCE GENERATOR initialization.
[0213] In addition, such a rule causes the UE performing the
OUTBAND D2D RELAY to transmit the PSSS and/or SSSS sequence for the
OOC purpose. However, the SIDELINK SYNCHRONIZATION ID and the
resources (related to the PSSS and/or SSSS transmission) may be
interpreted to be signaled from the base station. In addition, if
such a rule applies, in one example, DRUE(s) that transmits a D2D
RELAY communication related SSS (and/or PSBCH) using CARRIER #Y may
be configured to transmit the D2D Relay communication related SSS
(and/or PSBCH) using the same resources. As another example, the
SIDELINK SYNCHRONIZATION ID used for determination of the ROOT
SEQUENCE INDEX related to the PSSS sequence generation and/or the
SIDELINK SYNCHRONIZATION ID used for the SSSS sequence generation
may be configured to use (or substitute) the SIDELINK
SYNCHRONIZATION ID value (e.g., {0, 1, . . . , 167} (see id_net in
Section 1) as preconfigured or pre-signaled for IC.
[0214] In one example, if the OOC D2D UE #K receives from the DRUE
#N, a SSS and/or a PSBCH to which some or all rules of the
above-described [the present Method #1] are applied, the
corresponding D2D Relay communication related SSS and/or PSBCH may
be defined to have SYNCHRONIZATION SOURCE SELECTION PRIORITY higher
than those received from other OOC D2D UEs using the CARRIER #Y (or
may be defined to have PRIORITY higher than those received from
other OOC D2D UEs using the CARRIER #Y in terms of D2D Relay
communication related SSS and/or PSBCH and/or DATA and/or DISCOVERY
receipt).
[0215] As another example, if the OOC D2D UE #K receives from the
DRUE #N, a SSS and/or a PSBCH to which some or all rules of the
above-described [the present Method #1] are applied, the
corresponding D2D Relay communication related SSS and/or PSBCH may
be defined to have SYNCHRONIZATION SOURCE SELECTION PRIORITY higher
than those received from other OOC D2D UEs using the CARRIER #Y but
to have SYNCHRONIZATION SOURCE SELECTION PRIORITY higher than those
received from other IC D2D UEs using the CARRIER #Y. Here, in one
example, these rules may be applicable to following cases: 1) case
when there are base stations performing WAN communication based on
CARRIER #Y and, thus, PARTIAL COVERAGE SCENARIO may occur; 2) a
case in which when DRUE #N configures/transmits the D2D RELAY
communication-related SSS and/or PSBCH, the ROOT SEQUENCE ID for
generating the sequence of PSSS and/or the SIDELINK SYNCHRONIZATION
ID for SSSS sequence generation use what is defined for the IC
purpose, and the IN-COVERAGE INDICATOR in the CONTENTS transmitted
through PSBCH is set to 0 (or the RESERVED FIELD is set to the
predefined value).
[0216] As another example, if DRUE #N is performing D2D
communication using UL CARRIER #X as well as CARRIER #Y, a rule may
be configured such that the D2D transmission (TX) operation (and/or
D2D reception (RX) operation) using CARRIER #X may have a higher
PRIORITY than the D2D transmission (TX) operation (and/or D2D
reception (RX) operation) using CARRIER #Y. Here, in one example,
the application of such a rule may result in interpretation that IC
D2D TX operation (and/or IC D2D RX operation) (that is, D2D
communication using UL CARRIER #X) has a higher priority than D2D
RELAY communication using CARRIER #Y.
[0217] As further example, if DRUE #N does not have the capability
to simultaneously perform D2D communication using UL CARRIER #X and
CARRIER #Y, the D2D REALY communication (or D2D RELAY operation)
using CARRIER #Y may be suppressed during a period in which D2D
communication is performed using UL CARRIER #X.
[0218] As another example, if DRUE #N is performing D2D
communication using UL CARRIER #X as well as CARRIER #Y, a rule may
be configured such that the D2D transmission (TX) operation (and/or
D2D reception (RX) operation) using CARRIER #Y may have a higher
PRIORITY than the D2D transmission (TX) operation (and/or D2D
reception (RX) operation) using CARRIER #X. In one example, if DRUE
#N does not have the capability to simultaneously perform D2D
communication using UL CARRIER #X and CARRIER #Y, the D2D REALY
communication (or D2D RELAY operation) using CARRIER #X may be
suppressed during a period in which D2D communication is performed
using UL CARRIER #Y. This rule may be applied only to following
cases: a case when the MEA_CARRIER of CARRIER #Y is set to DL
CARRIER #X through predefined signaling, or a case when the DRUE #N
relays (system) information of a base station performing WAN
communication based on DL CARRIER #X using the CARRIER #Y.
[0219] In another example, the DRUE may use the predefined method
(or rule) to indicate the presence thereof to other D2D OOC UEs,
even though the DRUE does not have the information to be
transmitted to other D2D OOC UEs (or PSCCH (PHYSICAL SIDELINK
CONTROL CHANNEL)/PSSCH (PHYSICAL SIDELINK SHARED CHANNEL)). In this
way, the OOC D2D UE can detect the corresponding DRU and transmit
DATA thereto to support (or perform) the RELAY operation with the
network. Here, in one example, DRUE may announce its existence to
the other D2D OOC UEs by sending a predefined special PSCCH and/or
SSS (for a pre-defined (or signaled) time/period, even though the
DRUE does not have the information to be transmitted to other D2D
OOC UEs (or PSCCH (PHYSICAL SIDELINK CONTROL CHANNEL)/PSSCH
(PHYSICAL SIDELINK SHARED CHANNEL)). Here, in one example, a group
destination ID field (GROUP DESTINATION ID FIELD) on the
corresponding PSCCH may be set to the predetermined (or signaled)
special value. In particular, in one example, the proposed scheme
may be applicable not only to OUTBAND D2D RELAY but also to INBAND
D2D RELAY. Here, the INBAND RELAY may be defined as a repeater when
the link between the base station and the repeater and the link
between the repeater and the user device share the same carrier
frequency.
[0220] As another example, DRUE may be configured to send the
predefined special PSCCH (for a predefined (or signaled)
time/period) regardless of traffic, thereby to ensure that DRUE may
reliably send SSS (for the predefined (or signaled) time/period).
Here, in one example, the GROUP DESTINATION ID FIELD on the PSCCH
may be set to a predefined (or signaled) specific value. As another
example, DRUE may be configured to perform an SSS transmission for
a predefined (or signaled) time/period even though there is no
information to be transmitted to other D2D OOC UEs (or
PSCCH/PSSCH).
[0221] As another example, when DRUE #N performs D2D RELAY
communication (or D2D communication) using CARRIER #Y based on some
or all of the above-described suggested rules, some or all
information in the following examples #A to #E may be defined such
that they are set (or assumed) to be the same as those for
MEA_CARRIER of CARRIER #Y (or a predefined or signaled specific
CARRIER, wherein WAN DL communication may be performed using the
specific CARRIER).
Example #A
[0222] DFN (D2D frame number) information. Among the PSBCH CONTENTS
transmitted using CARRIER #Y, the DFN field may be set equally to
the SFN (SYSTEM (SUB) FRAME NUMBER) of the corresponding
MEA_CARRIER. In this case, the D2D RELAY communication (or D2D
communication) related time/frequency synchronization using CARRIER
#Y may be interpreted as equal to that for the MEA_CARRIER.
Example #B
[0223] TDD UL-DL CONFIGURATION information. If the MEA_CARRIER of
CARRIER #Y is an FM CARRIER, the TDD UL-DL CONFIGURATION field in
the PSBCH CONTENTS transmitted using CARRIER #Y is set to `000`. If
MEA_CARRIER of CARRIER #Y is TDD CARRIER, the TDD UL-DL
CONFIGURATION field in the PSBCH CONTENTS transmitted using CARRIER
#Y may be set to equally point to the TDD UL-DL CONFIGURATION of
the corresponding MEA_CARRIER. In another example, the TDD UL-DL
CONFIGURATION field in the PSBCH CONTENTS transmitted using CARRIER
#Y may be a FDD CARRIER (/BAND) or a CARDER_CONDITION field may be
configured such that the corresponding TDD UL-DL CONFIGURATION
field value is determined depending on whether the CARRIER #Y is a
TDD CARRIER (/BAND) or FDD CARRIER (/BAND), regardless of whether
the MEA_CARRIER is a FDD CARRIER or a TDD CARRIER.
[0224] In another example, if the TDD UL-DL CONFIGURATION field in
the PSBCH CONTENTS transmitted using CARRIER #Y indicates a TDD
system (or (actual) TDD UL-DL CONFIGURATION) according to the
proposed rule, interworking/matching relationship between the TIME
RESOURCE PATTERN field value on the PSCCH (SCI FORMAT 0) and the
SUBFRAME INDICATOR BITMAP, which determines the time resolution
pattern of the (MODE1) PSSCH transmitted using CARRIER #Y may be
defined with reference to TABLE defined for performing D2D
communication on the TDD system (as defined in the 3GPP TS 36.213
specification). To the contrary, if the TDD UL-DL CONFIGURATION
field in the PSBCH CONTENTS transmitted using CARRIER #Y indicates
FDD system (i.e., `000`), the interworking/matching relationship
between the TIME RESOURCE PATTERN field value on the PSCCH (SCI
FORMAT 0) and the SUBFRAME INDICATOR BITMAP, which determines the
time resolution pattern of the (MODE1) PSSCH transmitted using
CARRIER #Y may be defined with reference to TABLE defined for
performing D2D communication on the FDD system (as defined in the
3GPP TS 36.213 specification). In still another example, if the TDD
UL-DL CONFIGURATION field in the PSBCH CONTENTS transmitted using
CARRIER #Y indicates (actual) TDD UL-DL CONFIGURATION or TDD system
according to the proposed rule, the TIME RESOURCE PATTERN
candidates (i.e., `ITRP` [1]) of MODE2 PSSCH may be defined to
assume (or refer to) those matching the corresponding TDD UL-DL
CONFIGURATION. To the contrary, if the TDD UL-DL CONFIGURATION
field in the PSBCH CONTENTS transmitted using CARRIER #Y indicates
FDD system (i.e., `000`), the TIME RESOURCE PATTERN candidates
(i.e., `ITRP` [1]) of MODE2 PSSCH may be defined to assume (or
refer to) those matching the corresponding FDD UL-DL
CONFIGURATION.
Example #C
[0225] IN-COVERAGE INDICATOR information. Among the PSBCH CONTENTS
transmitted using CARRIER #Y, the IN-COVERAGE INDICATOR field may
be set according to the IN/OOC status for the corresponding
MEA_CARRIER.
Example #D
[0226] CARRIER #Y's MEA_CARRIER (or a predefined (or signaled)
specific CARRIER (to which WAN DL communication is performed) and
PAIRED UL CARRIER related DISCOVERY and/or COMMUNICATION and/or
SSS/PSBCH transmission (and/or receiving) related RESOURCE POOL
setting information.
Example #E
[0227] Time (or subframe or radio frame) (and/or frequency)
synchronization. As another example, the rule may be defined to
(always) synchronize time (or subframe or radio frame) to PCell (or
RELAY communication related SCI FORMAT 0 (D2D GRANT) transmission
related SCHEDULING CELL (i.e., MODE 1)) regardless of
MEA_CARRIER.
[0228] As another example, a rule may be defined such that
regardless of whether MEA_CARRIER of CARRIER #Y is a TDD/FDD
CARRIER, at least one of the TDD UL-DL CONFIGURATION field, the DFN
field, the IN-COVERAGE INDICATOR field, the SIDELINK SYSTEM
BANDWIDTH, and the RESERVED FIELDs in the PSBCH CONTENTS
transmitted using CARRIER #Y may be set (or fixed) to a predefined
(or signaled) value Here, as an example of the application of the
proposed scheme, the TDD UL-DL CONFIGURATION field in the PSBCH
CONTENTS transmitted using CARRIER #Y may be set or fixed to a
predefined (or signaled) `000` is. In this case, CARRIER #Y may be
interpreted as a (virtual) FDD UL CARRIER. As another example, a
rule may be defined such that when DRUE #N performs D2D RELAY
communication (based on MODE1) using CARRIER #Y, it transmits SCI
FORMAT 0 (D2D GRANT) (related to RELAY communication) based on
CROSS CARRIER SCHEDULING using other CARRIERs.
[0229] As another example, when the D2D UE #X performs D2D
communication using a preset (or signaled) CARRIER #T and CARRIER
#F, if the CARRIER #F is considered (or determined) for OOC and the
CARRIER #T is considered (or determined) for IC, transmission of at
least one of SSS, PSBCH, PSCCH, PSSCH, and PSDCH (PHYSICAL SIDELINK
DISCOVERY CHANNEL) using CARRIER #F may be done according to some
or all of the following rules/assumptions. Here, in one example,
CARRIER #F may be interpreted as a CARRIER dedicated to V2V
communication (VEHICLE TO VEHICLE communication, which may be
interpreted as direct communication between vehicles). Also, by way
of example, these rules/assumptions may be used only when D2D UE #X
does not perform D2D RELAY communication (using CARRIER #F) (or if
D2D UE #X is not set to DRUE using CARRIER #F).
Example #A
[0230] The SIDELINK SYNCHRONIZATION ID used in the determination of
the ROOT SEQUENCE INDEX related to the generation of the PSSS
sequence transmitted using CARRIER #F, and/or the SIDELINK
SYNCHRONIZATION ID (see Section 1) used for generating the SSSS
sequence may be configured to use SIDELINK SYNCHRONIZATION ID
values (in one example, {168, 169, . . . , 335} (see id_oon in
Section 1) as pre-signaled (or preset) for OOC. Here, in one
example, SSS (and/or PSBCH) transmission related resources may also
be pre-signaled (or preset). If such a rule applies, in one
example, a D2D UE(s) that transmits an SSS (and/or PSBCH) (related
to V2V communication) using CARRIER #F (for V2V communication only)
may be configured to use the same SIDELINK SYNCHRONIZATION ID for
generation of PSSS and/or SSSS sequence (and/or for initialization
of the PSBCH SCRAMBLING SEQUENCE GENERATOR). In addition, if such a
rule applies, in one example, a D2D UE(s) that transmits an SSS
(and/or PSBCH) (related to V2V communication) using CARRIER #F (for
V2V communication only) may be configured to transmit the
corresponding SSS (and/or PSBCH) using the same resources. In
another example, the SIDELINK SYNCHRONIZATION ID used in the
determination of the ROOT SEQUENCE INDEX related to the generation
of the PSSS sequence transmitted using CARRIER #F, and/or the
SIDELINK SYNCHRONIZATION ID used for generating the SSSS sequence
may be configured to use SIDELINK SYNCHRONIZATION ID values (in one
example, {0, 1, . . . , 167} (see id_net in Section 1) as
pre-signaled (or preset) for IC.
Example #B
[0231] Some or all of the following information (that is, at least
one of the examples #B-1 to #B-5 to be described later) relating to
the pre-established (or pre-signaled) CARRIER (referred to as
`REF_CARRIER`) may be equally applied to the transmission of at
least one of the SSS, PSBCH, PSCCH, PSSCH and PSDCH using the
CARRIER #F. For example, REF_CARRIER may be defined as a PCell or a
SCHEDULING CELL (i.e., MODE 1) associated with (V2V
communication-related) SCI FORMAT 0 (D2D GRANT) transmission
regardless of whether it is MEA_CARRIER of CARRIER #F or UL CARRIER
paired with MEA_CARRIER of CARRIER #T (or a predefined (or
signaled) specific CARRIER (via which WAN DL communication is
performed)).
Example #B-1
[0232] DFN information. Here, in one example, among the PSBCH
CONTENTS transmitted using CARRIER #F, the DFN field may be set
equally to the SFN (SYSTEM (SUB) FRAME NUMBER) of the corresponding
REF_CARRIER. In this case, the D2D communication related time
(/frequency) synchronization using CARRIER #F may be interpreted as
being equal to that using the REF_CARRIER.
Example #B-2
[0233] TDD UL-DL CONFIGURATION information. For example, if
REF_CARRIER of CARRIER #F is FDD CARRIER, the TDD UL-DL
CONFIGURATION field in PSBCH CONTENTS transmitted using CARRIER #F
is set to `000`. When REF_CARRIER of CARRIER #F is TDD CARRIER, the
TDD UL-DL CONFIGURATION field in PSBCH CONTENTS transmitted using
CARRIER #F may be set to equally point to the TDD UL-DL
CONFIGURATION of the corresponding REF_CARRIER. As another example,
the TDD UL-DL CONFIGURATION field in the PSBCH CONTENTS transmitted
using CARRIER #F may be configured such that the corresponding TDD
UL-DL CONFIGURATION field value is determined based on whether
CARRIER # is a FDD CARRIER (BAND) or a TDD CARRIER (BAND)
regardless of whether the REF_CARRIER is an FDD CARRIER or a TDD
CARRIER. As another example, if the TDD UL-DL CONFIGURATION field
in PSBCH CONTENTS transmitted using CARRIER #F indicates a TDD
system (or (actual) TDD UL-DL CONFIGURATION) according to the
proposed rule, interworking/matching relationship between the TIME
RESOURCE PATTERN field value on the PSCCH (SCI FORMAT 0) and the
SUBFRAME INDICATOR BITMAP, which determines the time resolution
pattern of the (MODE1) PSSCH transmitted using CARRIER #Y may be
defined with reference to TABLE defined for performing D2D
communication on the TDD system (as defined in the 3GPP TS 36.213
specification). To the contrary, if the TDD UL-DL CONFIGURATION
field in PSBCH CONTENTS transmitted using CARRIER #F indicates a
FDD system (i.e., `000`), the interworking/matching relationship
between the TIME RESOURCE PATTERN field value on the PSCCH (SCI
FORMAT 0) and the SUBFRAME INDICATOR BITMAP, which determines the
time resolution pattern of the (MODE1) PSSCH transmitted using
CARRIER #Y may be defined with reference to TABLE defined for
performing D2D communication on the FDD system (as defined in the
3GPP TS 36.213 specification). In still another example, if the TDD
UL-DL CONFIGURATION field in the PSBCH CONTENTS transmitted using
CARRIER #Y indicates (actual) TDD UL-DL CONFIGURATION or TDD system
according to the proposed rule, the TIME RESOURCE PATTERN
candidates (i.e., `ITRP` [1]) of MODE2 PSSCH may be defined to
assume (or refer to) those matching the corresponding TDD UL-DL
CONFIGURATION. To the contrary, if the TDD UL-DL CONFIGURATION
field in the PSBCH CONTENTS transmitted using CARRIER #Y indicates
FDD system (i.e., `000`), the TIME RESOURCE PATTERN candidates
(i.e., `ITRP` [1]) of MODE2 PSSCH may be defined to assume (or
refer to) those matching the corresponding FDD UL-DL
CONFIGURATION.
Example #B-3
[0234] IN-COVERAGE INDICATOR information. Here, for example, among
the PSBCH CONTENTS transmitted using CARRIER #F, the IN-COVERAGE
INDICATOR field may be set according to the IN/OOC status of the
corresponding REF_CARRIER.
Example #B-4
[0235] RESOURCE POOL setting information related to REF_CARRIER
related DISCOVERY and/or COMMUNICATION and/or SSS/PSBCH
transmission (and/or reception).
Example #B-5
[0236] Time (or subframe or radio frame) (and/or frequency)
synchronization. As another example, a rule may be defined to
synchronize (always) time (or subframe or radio frame) to
REF_CARRIER.
[0237] In the following, it is assumed that the user device
performs D2D operation in CARRIER #X. When TIMING REFERENCE (CELL)
associated with the D2D TX and/or D2D RX operation using CARRIER #X
(for example, SCELL (or NON-PCELL) or NON-SERVING CELL) is set or
signaled to PCELL (hereinafter referred to as REFER_CELL) (or other
CARRIER (as pre-signaled or predefined) other than CARRIER #X
and/or when the RESOURCE POOL information associated with the D2D
TX and/or D2D RX operation using CARRIER #X is received (or
CROSS-CARRIER-signaled) from the REFER_CELL other than the CARRIER
#X, some or all of the following rules may be defined to be applied
thereto.
[0238] That is, when the UE is set to comply with the time
reference of a carrier other than the carrier wave CARRIER #X
performing the D2D operation (more specifically, the time reference
of a cell using the other carrier) or to receive the resource pool
information from the cell using the other carrier wave, some or all
of the following rules may be defined to be applied thereto. The
cell using the other carrier providing the time reference or
providing the resource pool information will be referred to as a
reference cell (REFER_CELL) hereinafter. The rules to be described
later may be defined to be limited to the user device in the RELL
connection state in the PCELL and/or the user device in the RRC
idle state in the PCELL.
[0239] (Rule 1-1) REFER_CELL indicates CARRIER #X-based OOC D2D
communication related RESOURCE POOL information and SIDELINK
SYNCHRONIZATION SIGNAL ID (SLSSID), together with CARRIER #X-based
IN-COVERAGE (INC) D2D communication related RESOURCE POOL
information and SLSSID information, and the like. This considers
the possibility that D2D communication using CARRIER #X becomes
OUT-OF-COVERAGE (OOC) from the viewpoint of D2D UE.
[0240] From the viewpoint of the D2D UE, when the D2D communication
using the CARRIER #X becomes OOC, the UE follows (exceptionally)
the (CARRIER #X based) TIMING in the OOC situation rather than the
REFER_CELL based TIMING REFERENCE (and/or TA), and further, a rule
may be defined to perform OOC D2D communication using CARRIER #X
based on OOC D2D communication related RESOURCE POOL information
and SLSSID received from the REFER_CELL. In an alternative, the UE
may comply with REFER_CELL based TIMING REFERENCE (TA) or comply
with both of REFER_CELL based TIMING REFERENCE and (CARRIER #X
based) TA setting in an OOC situation, and, further, the rule may
be defined to perform OOC D2D communication using CARRIER #X based
on OOC D2D communication related RESOURCE POOL information and
SLSSID received from the REFER_CELL. As another example, when a D2D
communication using CARRIER #X is INC from the viewpoint of a D2D
UE, the UE may comply with REFER_CELL based TIMING REFERENCE (TA)
(or comply with both of REFER_CELL based TIMING REFERENCE and
(CARRIER #X based) TA setting in an OOC situation), and, further,
the rule may be defined to perform INC D2D communication using
CARRIER #X based on INC D2D communication related RESOURCE POOL
information and SLSSID received from the REFER_CELL.
[0241] (Rule 1-2) REFER_CELL indicates D2D UE of at least one of
common RESOURCE POOL information and SLSSID information to be
commonly used for OOC D2D communication and INC D2D communication
using the CARRIER #X. Thus, D2D UE may perform at least one of
CARRIER #X-based OOC D2D communication and INC D2D communication
based on the indicated RESOURCE POOL information and SLSSID
information.
[0242] In one example, if a D2D communication using CARRIER #X is
OOC from a viewpoint of an D2D UE, the UE follows (exceptionally)
the (CARRIER #X based) TIMING in the OOC situation rather than the
REFER_CELL based TIMING REFERENCE (and/or TA), and further, the UE
may perform OOC D2D communication using CARRIER #X based on
(common) D2D communication related RESOURCE POOL information and
SLSSID received from the REFER_CELL. In an alternative, the UE may
comply with REFER_CELL based TIMING REFERENCE (TA) or comply with
both of REFER_CELL based TIMING REFERENCE and (CARRIER #X based) TA
setting in an OOC situation, and, further, the UE may perform OOC
D2D communication using CARRIER #X based on (common) D2D
communication related RESOURCE POOL information and SLSSID received
from the REFER_CELL. As another example, when a D2D communication
using CARRIER #X is INC from the viewpoint of a D2D UE, the UE may
comply with REFER_CELL based TIMING REFERENCE (TA) (or comply with
both of REFER_CELL based TIMING REFERENCE and (CARRIER #X based) TA
setting in an OOC situation), and, further, the UE may perform INC
D2D communication using CARRIER #X based on (common) D2D
communication related RESOURCE POOL information and SLSSID received
from the REFER_CELL.
[0243] On the other hand, when the NON-SERVING CELL (and/or SCELL)
performing D2D TX (/RX) operation is determined (or assumed) to be
IN-COVERAGE, frequency synchronization and/or time synchronization
related to D2D TX (/RX) operation in the NON-SERVING CELL may be
done in accordance with all or some of the following rules.
[0244] Here, it is assumed that the SERVING CELL (and/or PCELL) and
the NON-SERVING CELL (and/or SCELL) use (or belong to) different
CARRIERs. In addition, some or all of the following rules may apply
only to a case when CARRIER associated with the NON-SERVING CELL
(and/or SCELL) and CARRIER associated with SERVING CELL (and/or
PCELL) have INTER-BAND (and/or INTRA-BAND CONTIGUOUS and/or
INTRA-BAND NON-CONTIGUOUS) relationship.
[0245] FIG. 12 illustrates a situation in which the user device
performs a D2D operation.
[0246] Referring to FIG. 12, the user device may be required to
perform a D2D operation at the F2 frequency while having a specific
cell serving as a serving cell (or PCELL) at F1 frequency. The user
device may be located within the coverage of the NON-SERVING CELL
(or SCELL) at F2 frequency. The NON-SERVING CELL (or SCELL) at the
F2 frequency may be referred to as an IN-COVERAGE NON-SERVING CELL
(or IN-COVERAGE SCELL).
[0247] In the situation described in FIG. 12, when the user device
attempts to perform the D2D operation, how to control frequency
synchronization and time synchronization is an issue. Hereinafter,
this issue will be described in detail.
[0248] (Rule #A-1) In performing the D2D operation (D2D
transmission or D2D reception), the user device adjusts frequency
synchronization and time synchronization according to predefined
rules (or signaled information) and then transmits D2D signals. The
user device may apply frequency synchronization related to D2D TX
(/RX) operation on the corresponding NON-SERVING CELL (and/or
SCELL) according to IN-COVERAGE NON-SERVING CELL (and/or SCELL). In
addition, the D2D TX (/RX) operation time synchronization on the
corresponding non-serving cell (and/or SCELL) may be (further)
applied or assumed according to the IN-COVERAGE NON-SERVING CELL
(and/or SCELL).
[0249] (Rule #A-2) The user device may apply or assume
synchronization of the D2D TX (/RX) operation on the corresponding
NON-SERVING CELL (and/or SCELL) according to the IN-COVERAGE
NON-SERVING CELL. In this connection, frequency synchronization may
be defined to follow PCELL (and/or SERVING CELL). That is, in FIG.
12, the user device adjusts the frequency synchronization according
to the serving cell (PCELL) at the F1 frequency, adjusts the time
synchronization according to the NON-SERVING CELL at the F2
frequency, and then performs the D2D operation.
[0250] FIG. 13 is a method for performing the D2D operation by the
user device when Rule #A-2 is applied.
[0251] Referring to FIG. 13, the user device applies frequency
synchronization based on a primary cell (or serving cell) at a
first frequency (S210). The user device applies time
synchronization based on the NON-SERVING CELL (or SCELL) at the
second frequency F2 intending to perform the D2D operation
(S220).
[0252] The user device performs the D2D operation by applying the
frequency synchronization and the time synchronization (S230).
[0253] For example, the user device, which is in the RRC connection
state with a specific cell at frequency #1 as the PCELL (or serving
cell), desires to perform the D2D operation at frequency #2. In
this connection, the cells at the frequency #2 may be NON-SERVING
CELL (or SCELL) for the user device. The user device may be within
the coverage of the NON-SERVING CELL (or SCELL). In this case, the
user device adjusts the frequency synchronization for the D2D
operation based on the PCELL (or serving cell) and adjusts the time
synchronization based on the NON-SERVING CELL (or SCELL) at the
frequency #2.
[0254] Rule #A-2 described above may be applied to a case when
SEARCHING WINDOW SIZE (related to the corresponding NON-SERVING
CELL) (or REFERENCE SYNCHRONIZATION WINDOW SIZE) is signaled (or
indicated) to have W2 (<CP LENGTH) (that is, when the difference
between the frequency (/time) synchronization according to the
NON-SERVING CELL (and/or SCELL) and the frequency (/time)
synchronization according to the PCELL (and/or SERVING CELL) is
small).
[0255] FIG. 14 illustrates another situation in which the user
device performs D2D operation.
[0256] Referring to FIG. 14, the user device may be required to
perform a D2D operation at the F2 frequency while having a specific
cell serving as a serving cell (or PCELL) at F1 frequency. The user
device may be located outside the coverage of the NON-SERVING CELL
(or SCELL) at the F2 frequency. In this case, the NON-SERVING CELL
(or SCELL) at the F2 frequency may be referred to as an
OUT-COVERAGE NON-SERVING CELL (or OUT-COVERAGE SCELL).
[0257] When it is assumed that the NON-SERVING CELL (and/or SCELL)
performing the D2D TX (/RX) operation is determined (or assumed) as
OUT-COVERAGE, and the PCELL (and/or SERVING CELL) is IN-COVERAGE,
the UE may apply frequency synchronization and/or time
synchronization related to the D2D TX (/RX) operation in the
corresponding NON-SERVING CELL (and/or SCELL) according to some or
all of the following rules.
[0258] It is assumed that the SERVING CELL (and/or PCELL) and the
NON-SERVING CELL (and/or SCELL) use (or belong to) different
CARRIERs. Some or all of the following rules may apply only to a
case when CARRIER associated with NON-SERVING CELL (and/or SCELL)
and CARRIER associated with SERVING CELL (and/or PCELL) have
INTER-BAND (and/or INTRA-BAND CONTIGUOUS and/or INTRA-CONTIGUOUS)
relationship.
[0259] (Rule #B-1) A rule may be defined to apply frequency
synchronization related to D2D TX(/RX) operation on the
corresponding NON-SERVING CELL (and/or SCELL)) based on the
IN-COVERAGE PCELL (and/or SERVING CELL). Here, as another example,
a rule may be defined to apply time synchronization related to D2D
TX(/RX) operation on the corresponding NON-SERVING CELL (and/or
SCELL)) based on the IN-COVERAGE PCELL (and/or SERVING CELL). Here,
in another example, if the corresponding D2D TX (/RX) UE has an
OUT-COVERAGE UE on the OUT-COVERAGE NON-SERVING CELL as a
SYNCHRONIZATION REFERENCE, a rule may be defined to apply frequency
synchronization and time synchronization related to D2D TX (/RX)
operation on the corresponding NON-SERVING CELL based on the
OUT-COVERAGE UE (SLSS thereof). In an alternative, a rule may be
defined to apply one of frequency synchronization and time
synchronization related to D2D TX (/RX) operation on the
corresponding NON-SERVING CELL based on the OUT-COVERAGE UE (SLSS
thereof), and to apply the other of frequency synchronization and
time synchronization related to D2D TX (/RX) operation on the
corresponding NON-SERVING CELL based on the IN-COVERAGE PCELL
(and/or SERVING CELL). Here, as another example, if the
corresponding D2D TX (/RX) UE does not have an OUT-COVERAGE UE on
the OUT-COVERAGE NON-SERVING CELL as a SYNCHRONIZATION REFERENCE
(i.e., the D2D TX (/RX) UE itself is an independent SYNCHRONIZATION
REFERENCE), frequency synchronization (and/or time synchronization)
related to D2D TX (/RX) operation on the corresponding non-serving
cell may be applied/assumed based on IN-COVERAGE PCELL. In an
alternative, D2D TX (/RX) UE itself configures (applies) one of
time synchronization and frequency synchronization) related to D2D
TX (/RX) operation, and the other of D2D TX/RX operation related
frequency synchronization and time synchronization) may be
applied/assumed based on IN-COVERAGE PCELL.
[0260] The proposed schemes described above may be implemented
independently, but may be implemented in the form of a combination
of some of the proposed schemes. The above-described proposed
schemes may be defined such that they are limitedly applied only to
the FDD system (and/or TDD system) environment. The proposed
schemes described above may be defined such that they are limited
to MODE 2 COMMUNICATION and/or TYPE 1 DISCOVERY (and/or MODE 1
COMMUNICATION and/or TYPE 2 DISCOVERY). In addition, the
above-described proposed schemes may be defined to be limited to
the IN-COVERAGE D2D UE (and/or OUT-COVERAGE D2D UE) (and/or
RRC_CONNECTED D2D UE (and/or RRC_IDLE D2D UE)). The proposed
schemes described above may be defined to be limited to only the
D2D UE that performs only the D2D DISCOVERY
(transmission/reception) (and/or the D2D UE performing only the D2D
COMMUNICATION (transmission/reception)). The proposed schemes
described above may be defined to be limited to only a situation
where only D2D DISCOVERY is supported (set) (and/or only D2D
COMMUNICATION is supported or set). The proposed schemes described
above may be defined to be limited only to a situation where the
D2D DISCOVERY SIGNAL reception operation is performed using in the
other (UL) CARRIER having the INTER-FREQUENCY (and/or a situation
where the D2D DISCOVERY SIGNAL reception operation is performed
using the other INTER-PLMN-based (UL) CARRIER). The proposed
schemes described above may be defined to be limited to the OUTBAND
D2D RELAY operation (and/or the INBAND D2D RELAY operation). The
above-described proposed schemes may be defined to be limited to a
situation where DRUE #N transmits D2D DISCOVERY-related (and/or
COMMUNICATION related) SSS, and/or PSBCH (related to RELAY
communication) using the CARRIER #Y. In addition, the proposed
schemes described above may also be applied to a situation where a
D2D UE performing a general D2D communication (not a D2D RELAY
operation) transmits D2D DISCOVERY-related (and/or D2D
COMMUNICATION related) SSS and/or PSBCH (and/or PSCCH and/or PSSCH
and/or PSDCH transmission) using the CARRIER #Y. Also, the
above-described proposed schemes may be defined to be limited to a
situation where the D2D operation is performed using a non-primary
carrier rather than a primary carrier. In addition, the
above-described proposed schemes may be defined to be limited to a
situation where there is no active serving cell using the carrier
on which the D2D operation is performed (or when there is no cell
to be detected).
[0261] FIG. 15 is a block diagram illustrating the user device in
which an embodiment of the present invention is implemented.
[0262] Referring to FIG. 15, the user device 1100 includes a
processor 1110, a memory 1120, and a radio frequency unit 1130.
Processor 1110 implements the proposed functionality, process
and/or method as set forth herein. For example, the processor 1110
may receive measurement carrier (MEA_CARRIER) indication
information indicating one downlink carrier used for downlink
measurement and synchronization for D2D operation, and may use one
downlink carrier indicated by the measurement carrier (MEA_CARRIER)
indication information to perform downlink measurement and
synchronization for the D2D operation.
[0263] The RF unit 1130 is connected to the processor 1110 to
transmit and receive radio signals.
[0264] The processor may comprise an application-specific
integrated circuit (ASIC), other chipset, logic circuitry and/or
data processing device. The memory may include read-only memory
(ROM), random access memory (RAM), flash memory, memory cards,
storage media, and/or other storage devices. The RF unit may
include a baseband circuit for processing the radio signal. When
the embodiment is implemented in software, the above-described
techniques may be implemented with modules (processes, functions,
and so on) that perform the functions described above. The module
may be stored in the memory and may be executed by the processor.
The memory may be internal or external to the processor, and may be
coupled to the processor by various well known means.
* * * * *