U.S. patent application number 16/737617 was filed with the patent office on 2020-05-07 for user equipment and communication method.
This patent application is currently assigned to NTT DOCOMO, INC.. The applicant listed for this patent is NTT DOCOMO, INC.. Invention is credited to Hiroki Harada, Satoshi Nagata, Shimpei Yasukawa.
Application Number | 20200145971 16/737617 |
Document ID | / |
Family ID | 58187515 |
Filed Date | 2020-05-07 |
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United States Patent
Application |
20200145971 |
Kind Code |
A1 |
Yasukawa; Shimpei ; et
al. |
May 7, 2020 |
USER EQUIPMENT AND COMMUNICATION METHOD
Abstract
A user equipment in a radio communication system supporting D2D
communication is disclosed that includes a determination unit that
receives a first region in a radio frame, which is commonly used
for downlink communication and uplink communication with a base
station and includes the first region to which a downlink pilot
signal and a downlink control signal are to be mapped and a second
region to which downlink user data or uplink data is to be mapped,
to determine whether a D2D signal is transmittable using the second
region.
Inventors: |
Yasukawa; Shimpei; (Tokyo,
JP) ; Nagata; Satoshi; (Tokyo, JP) ; Harada;
Hiroki; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NTT DOCOMO, INC. |
Tokyo |
|
JP |
|
|
Assignee: |
NTT DOCOMO, INC.
Tokyo
JP
|
Family ID: |
58187515 |
Appl. No.: |
16/737617 |
Filed: |
January 8, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15755256 |
Feb 26, 2018 |
10568084 |
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PCT/JP2016/074253 |
Aug 19, 2016 |
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16737617 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
Y02D 70/00 20180101;
Y02D 30/70 20200801; Y02D 70/20 20180101; H04W 28/06 20130101; Y02D
70/1262 20180101; H04W 72/042 20130101; H04L 5/0048 20130101; H04W
92/18 20130101; Y02D 70/21 20180101; Y02D 70/1264 20180101; H04W
72/04 20130101 |
International
Class: |
H04W 72/04 20060101
H04W072/04; H04L 5/00 20060101 H04L005/00; H04W 28/06 20060101
H04W028/06; H04W 92/18 20060101 H04W092/18 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 1, 2015 |
JP |
2015-172392 |
Claims
1. A user equipment in a radio communication system that supports
D2D communication, the user equipment comprising: a determination
unit that receives a first region in a radio frame, which is
commonly used for downlink communication and uplink communication
with a base station and includes the first region to which a
downlink pilot signal and a downlink control signal are to be
mapped and a second region to which downlink user data or uplink
data is to be mapped, to determine whether a D2D signal is
transmittable using the second region.
2. The user equipment according to claim 1, wherein the
determination unit determines that the D2D signal is transmittable
using the second region when the first region does not include a
control signal indicating that the second region is allocated to
the uplink communication or the downlink communication with the
base station or when reception power of the first region is less
than or equal to a predetermined threshold value.
3. The user equipment according to claim 1, further comprising: a
transmission unit that transmits the D2D signal using the second
region in the radio frame where a D2D physical control channel and
a D2D physical data channel are time-multiplexed when the
determination unit determines that the D2D signal is transmittable,
wherein the transmission unit transmits the D2D signal using a
frequency band other than a predetermined frequency band in the
second region when only the predetermined frequency band is
allocated to the uplink communication or the downlink communication
with the base station.
4. The user equipment according to claim 3, wherein the
transmission unit transmits the D2D signal with transmission power
specified by the base station using the frequency band other than
the predetermined frequency band.
5. The user equipment according to claim 3, wherein the
transmission unit transmits the D2D signal using the second region
when the determination unit determines multiple times in succession
that the D2D signal is transmittable.
6. The user equipment according to claim 4, wherein the
transmission unit transmits the D2D signal using the second region
when the determination unit determines multiple times in succession
that the D2D signal is transmittable.
7. The user equipment according to claim 2, further comprising: a
transmission unit that transmits the D2D signal using the second
region in the radio frame where a D2D physical control channel and
a D2D physical data channel are time-multiplexed when the
determination unit determines that the D2D signal is transmittable,
wherein the transmission unit transmits the D2D signal using a
frequency band other than a predetermined frequency band in the
second region when only the predetermined frequency band is
allocated to the uplink communication or the downlink communication
with the base station.
8. The user equipment according to claim 7, wherein the
transmission unit transmits the D2D signal with transmission power
specified by the base station using the frequency band other than
the predetermined frequency band.
9. The user equipment according to claim 7, wherein the
transmission unit transmits the D2D signal using the second region
when the determination unit determines multiple times in succession
that the D2D signal is transmittable.
10. The user equipment according to claim 1, further comprising: a
transmission unit that transmits the D2D signal using the second
region in the radio frame where a D2D physical control channel and
a D2D physical data channel are time-multiplexed when the
determination unit determines that the D2D signal is transmittable,
wherein the transmission unit transmits the D2D signal using the
second region when the determination unit determines multiple times
in succession that the D2D signal is transmittable.
11. The user equipment according to claim 10, wherein a number of
symbols of the radio frame is equal to a number of symbols
corresponding to a region to which the downlink user data or the
uplink data is mapped in a radio frame used in a carrier where
communication between the base station and the user equipment is
performed.
12. The user equipment according to claim 1, further comprising: a
transmission unit that transmits the D2D signal using the second
region in the radio frame where a D2D physical control channel and
a D2D physical data channel are time-multiplexed when the
determination unit determines that the D2D signal is transmittable,
wherein the transmission unit repeatedly transmits the D2D signal
based on a predetermined hopping pattern.
13. A user equipment in a radio communication system that supports
D2D communication, the user equipment comprising: an acquisition
unit that acquires carrier information indicating whether each of
multiple carriers allocated to the radio communication system is
used commonly for communication between a base station and the user
equipment and D2D communication or used only for the D2D
communication.
14. The user equipment according to claim 13, further comprising: a
transmission unit that when a D2D signal is to be transmitted using
a carrier used only for the D2D communication, transmits the D2D
signal using a radio frame where a D2D physical control channel and
a D2D physical data channel are time-multiplexed, wherein the
transmission unit repeatedly transmits the D2D signal based on a
predetermined hopping pattern.
15. A communication method performed by a user equipment in a radio
communication system that supports D2D communication, the
communication method comprising: receiving a first region in a
radio frame, which is commonly used for downlink communication and
uplink communication with a base station and includes the first
region to which a downlink pilot signal and a downlink control
signal are to be mapped and a second region to which downlink user
data or uplink data is to be mapped, and thereby determining
whether a D2D signal is transmittable using the second region.
16. A communication method performed by a user equipment in a radio
communication system that supports D2D communication, the
communication method comprising: acquiring carrier information
indicating whether each of multiple carriers allocated to the radio
communication system is used commonly for communication between a
base station and the user equipment and D2D communication or used
only for the D2D communication.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation of U.S.
Application and, thereby, claims benefit under 35 U.S.C. .sctn. 120
to U.S. Application No. 15/755,256, filed on Feb. 26, 2018, titled
"USER EQUIPMENT AND COMMUNICATION METHOD," which is a U.S. Nation
Stage Application of PCT Application No. PCT/JP2016/074253, filed
on Aug. 19, 2016, which claims priority to Japanese Patent
Application No. 2015-172392, filed on Sep. 1, 2015. The contents of
the priority applications are incorporated by reference in their
entirety.
TECHNICAL FIELD
[0002] The present invention relates to a user equipment and a
communication method.
BACKGROUND ART
[0003] In a long term evolution (LTE) system or a system successive
to the LTE system (also referred to as, for example, LTE-advanced
(LTE-A), future radio access (FRA), or 4G), Device to Device (D2D)
technology allowing user terminals to directly communicate with
each other without using a radio base station has been studied (for
example, see Non-Patent Document 1).
[0004] The D2D technology can reduce traffic between a user
equipment and a base station and enable communication between user
equipments even when a base station becomes incommunicable at the
time of disaster or the like.
[0005] The D2D technology is roughly classified into D2D discovery
(also referred to as D2D detection) for discovering another user
terminal which is communicable and D2D communication (also referred
to as D2D direct communication, direct communication between
terminals) for allowing terminals to directly communicate with each
other. Hereinafter, when the D2D communication and the D2D
discovery are not to be particularly distinguished, the
[0006] D2D communication and the D2D discovery are simply referred
to as D2D. A signal which is transmitted and received by D2D is
referred to as a D2D signal.
RELATED-ART DOCUMENT
Non-Patent Document
[0007] [Non-Patent Document 1]"Key drivers for LTE success:
Services Evolution", September, 2011, 3GPP, Internet URL:
http://www.3gpp.org/ftp/Information/presentations/presentations_2011/2011-
_09_ LTE_Asia/2011_LTE-Asia_3GPP_Service_evolution.pdf
SUMMARY OF THE INVENTION
Problem to be Solved by the Invention
[0008] In 3rd Generation Partnership Project (3GPP), realization of
V2X has been studied by using a D2D function. Here, V2X is a
generic term of vehicle to vehicle (V2V) referring to a
communication scheme which is performed between vehicles, vehicle
to infrastructure (V2I: communication between road and vehicle)
referring to a communication scheme which is performed between a
vehicle and a road-side unit installed at a roadside, vehicle to
Nomadic device (V2N: communication between device and vehicle)
referring to a communication scheme which is performed between a
vehicle and a mobile device of a driver, and vehicle to pedestrian
(V2P: communication between pedestrian and vehicle) referring to a
communication scheme which is performed between a vehicle and a
mobile device of a pedestrian. In V2X, it is assumed that important
communication (for example, communication for accident prevention,
congestion avoidance, and the like) is handled, and thus there is
demand for a more decrease in delay than in convention D2D.
[0009] In 3GPP, fifth-generation (5G) radio technology which is a
next-generation radio communication system has been studied. An
example of requirements proposed in 5G is achievement of a more
decrease in delay in radio sections. In the D2D technology, demand
for a decrease in delay in consideration of requirements of 5G is
assumed. In this way, there is demand for a more decrease in delay
in D2D communication with enlargement in use form and advancement
in radio technology, but in the current D2D technology, there is a
large delay because a control signal and a data signal are
periodically transmitted at a relatively long interval (40 ms).
[0010] A technology disclosed herein is made in consideration of
the above-mentioned circumstances and an object thereof is to
provide a technology that enables D2D communication with a low
delay.
Means for Solving the Problems
[0011] The disclosed technology provides a user equipment in a
radio communication system that supports D2D communication. The
user equipment includes a determination unit that receives a first
region in a radio frame, which is commonly used for downlink
communication and uplink communication with a base station and
includes the first region to which a downlink pilot signal and a
downlink control signal are to be mapped and a second region to
which downlink user data or uplink data is to be mapped, to
determine whether a D2D signal is transmittable using the second
region; and a transmission unit that transmits the D2D signal using
the second region in the radio frame where a D2D physical control
channel and a D2D physical data channel are time-multiplexed when
the determination unit determines that the D2D signal is
transmittable.
[0012] The disclosed technology also provides a user equipment in a
radio communication system that supports D2D communication. The
user equipment includes an acquisition unit that acquires carrier
information indicating whether each of multiple carriers allocated
to the radio communication system is used commonly for
communication between a base station and the user equipment and D2D
communication or used only for the D2D communication; and a
transmission unit that when a D2D signal is to be transmitted using
a carrier used only for the D2D communication, transmits the D2D
signal using a radio frame where a D2D physical control channel and
a D2D physical data channel are time-multiplexed.
Advantageous Effect of the Invention
[0013] According to the disclosed technology, it is possible to
provide a technology that enables D2D communication with a low
delay.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a diagram illustrating an example of a
configuration of a radio communication system according to an
embodiment;
[0015] FIG. 2A is a diagram illustrating an example of a physical
channel configuration which is studied in 5G;
[0016] FIG. 2B is a diagram illustrating an example of a physical
channel configuration which is studied in 5G;
[0017] FIG. 3A is a diagram illustrating D2D physical channel
configuration (1-1) according to the embodiment;
[0018] FIG. 3B is a diagram illustrating D2D physical channel
configuration (1-1) according to the embodiment;
[0019] FIG. 3C is a diagram illustrating D2D physical channel
configuration (1-1) according to the embodiment;
[0020] FIG. 4A is a diagram illustrating D2D physical channel
configuration (1-2) according to the embodiment;
[0021] FIG. 4B is a diagram illustrating D2D physical channel
configuration (1-2) according to the embodiment;
[0022] FIG. 5A is a diagram illustrating D2D physical channel
configuration (1-3) according to the embodiment;
[0023] FIG. 5B is a diagram illustrating D2D physical channel
configuration (1-3) according to the embodiment;
[0024] FIG. 6A is a diagram illustrating D2D physical channel
configuration (1-4) according to the embodiment;
[0025] FIG. 6B is a diagram illustrating D2D physical channel
configuration (1-4) according to the embodiment;
[0026] FIG. 7 is a diagram illustrating D2D physical channel
configuration (1-5) according to the embodiment;
[0027] FIG. 8 is a diagram illustrating a relationship between a
D2D resource pool and a D2D physical channel configuration;
[0028] FIG. 9A is a diagram illustrating D2D physical channel
configuration (2) according to the embodiment;
[0029] FIG. 9B is a diagram illustrating D2D physical channel
configuration (2) according to the embodiment;
[0030] FIG. 10A is a diagram illustrating an example in which 5G
radio resources and D2D radio resources are
frequency-multiplexed;
[0031] FIG. 10B is a diagram illustrating an example in which 5G
radio resources and D2D radio resources are
frequency-multiplexed;
[0032] FIG. 11A is a diagram illustrating a method of instructing
radio resources capable of transmitting a D2D signal;
[0033] FIG. 11B is a diagram illustrating a method of instructing
radio resources capable of transmitting a D2D signal;
[0034] FIG. 11C is a diagram illustrating a method of instructing
radio resources capable of transmitting a D2D signal;
[0035] FIG. 12 is a diagram illustrating a method of transmitting a
D2D signal after checking an emptiness state of D2D radio
resources;
[0036] FIG. 13 is a diagram illustrating a method of repeatedly
transmitting a D2D signal;
[0037] FIG. 14 is a diagram illustrating a method of repeatedly
transmitting a D2D signal;
[0038] FIG. 15 is a diagram illustrating a method of enhancing a
recognition rate of D2D radio resources;
[0039] FIG. 16 is a diagram illustrating an example of a functional
configuration of a user equipment according to the embodiment;
[0040] FIG. 17 is a diagram illustrating an example of a functional
configuration of a base station according to the embodiment;
and
[0041] FIG. 18 is a diagram illustrating an example of a hardware
configuration of a user equipment and a base station according to
the embodiment.
DESCRIPTION OF EMBODIMENTS
[0042] Hereinafter, embodiments of the invention will be described
with reference to the accompanying drawings. The embodiments
described below are only examples and embodiments of the invention
are not limited to the following embodiments. For example, a radio
communication system according to the embodiments is assumed to be
a LTE-based system, but the invention is not limited to the LTE and
can be applied to another scheme. In the specification and the
appended claims, "LTE" is used in a wide meaning including
fifth-generation communication schemes corresponding to Releases
10, 11, 12, 13, and 14 of 3GPP and releases subsequent thereto as
well as communication schemes corresponding to Releases 8 and 9 of
3GPP.
[0043] The following embodiment is described with the premise of a
physical channel configuration which is studied in 5G, but
application of the embodiment to only 5G is not intended. All or a
part of the embodiment can be applied to various radio
communication systems.
[0044] In the following description, one TTI is used to have a
minimum unit of scheduling. One subframe is assumed to have the
same length as one TTI and may be replaced with another term. A
pilot signal is used to have the same meaning as a reference
signal.
<<System Configuration>>
[0045] FIG. 1 is a diagram illustrating an example of a
configuration of a radio communication system according to an
embodiment. As illustrated in FIG. 1, a radio communication system
according to this embodiment includes a base station eNB, a
transmission-side user equipment UEa, and a reception-side user
equipment UEb. In FIG. 1, the transmission-side user equipment UEa
and the reception-side user equipment UEb are separately
illustrated, but the transmission-side user equipment UEa and the
reception-side user equipment UEb have the same D2D communication
function (a function of transmitting and receiving a D2D signal).
In the following description, any user equipment of the user
equipment UEa and the user equipment UEb is referred to as a "user
equipment UE."
[0046] The user equipment UE has a cellular communication function
and a D2D communication function. The base station eNB has a
function of performing various instructions (such as allocation of
D2D resources) required for transmitting and receiving a D2D signal
to the user equipment UE, for example, using broadcast information
(system information such as SIB), radio resource control (RRC)
signaling, or the like.
<<D2D Physical Channel Configuration>>
[0047] A D2D physical channel configuration which is used by the
user equipment UE according to this embodiment to perform D2D
communication will be described below. It is assumed that D2D
physical channel configuration (1) to be described below is mainly
used to perform an operation of overlapping 5G radio resources and
D2D radio sources and D2D physical channel configuration (2) is
mainly used to perform an operation when it is not necessary to
consider interference with 5G radio resources, like a D2D dedicated
carrier.
<5G Physical Channel Configuration>
[0048] A physical channel configuration which is studied in 5G will
be first described below before describing a physical channel
configuration which is used for D2D communication.
[0049] FIGS. 2A and 2B are diagrams illustrating an example of a
physical channel configuration which is studied in 5G. As
illustrated in FIGS. 2A and 2B, it is proposed that a radio frame
which is used for 5G between the base station eNB and the user
equipment UE includes a region (Region "A" in FIGS. 2A and 2B) to
which a pilot signal and a downlink control signal are mapped and a
region (Region "B" in FIGS. 2A and 2B) to which data is mainly
mapped in one TTI.
[0050] Region "A" is additionally partitioned into a pilot signal
region (DL pilot) to which a downlink pilot signal is mapped and a
control signal region (DL control) to which a downlink control
signal is mapped. The downlink control signal mapped on the control
signal region is, for example, a signal including scheduling
information and/or various control signals such as a UL grant, like
downlink control information (DCI). The control signal includes use
information indicating a use of multi-use region to be described
later.
[0051] Region "B" is partitioned into a data region to which DL
data or UL data is mapped and a multi-use region (Flex). In 5G,
application of dynamic time division duplex (TDD) of dynamically
switching uplink and downlink in the unit of TTI is studied and
arbitrary switching between use of the data region and the
multi-use region for transmission of DL data or transmission of UL
data using the downlink control signal which is mapped on the
control signal region is studied. For example, a use method of
mapping DL data on the data region when DL scheduling information
(DL assignment) is included in the downlink control signal and
mapping UL data on the data region when UL scheduling information
(UL grant) is included in the downlink control signal is
studied.
[0052] The multi-use region may be used in a part of the data
region or may be used to transmit ACK/NACK (A/N) in response to DL
data. The multi-used region may be used for transmission of an
additional pilot signal and a guard period.
[0053] FIG. 2A illustrates an example of a physical channel
configuration in which DL data is mapped on the data region, and
FIG. 2B illustrates an example of a physical channel configuration
in which UL data is mapped on the data region. When UL data is
mapped on the data region, it is studied that an uplink pilot
signal (UL pilot) is mapped on the head of the data region as
illustrated in FIG. 2B. UL data may include uplink control
information (UCI).
[0054] As for TDM of a plurality of signals (channels), various
sequences or combination are considered and the invention is not
limited to the sequence or combination illustrated in FIGS. 2A and
2B.
[0055] The vertical axis in FIGS. 2A and 2B represents a frequency
axis and is not limited to a whole band, but may be a part of a
band. This is because it is also studied in 5G that a whole band is
divided into a plurality of sub bands and a radio frames having
different TTI lengths are frequency-multiplexed (FDM). When the
dynamic TDD is applied, switching of uplink/downlink in the unit of
a whole band or sub bands is assumed.
<D2D Physical Channel Configuration (1)>
[0056] Subsequently, a plurality of examples of the configuration
of D2D physical channel configuration (1) will be described below.
In the following description, "D2D physical channel configuration
(1)" is used in a meaning including D2D physical channel
configurations (1-1) to (1-5).
(D2D Physical Channel Configuration (1-1))
[0057] FIGS. 3A, 3B, and 3C are diagrams illustrating D2D physical
channel configuration (1-1) in the embodiment. As illustrated in
FIGS. 3A, 3B, and 3C, in this embodiment, a physical channel
configuration in which a D2D pilot signal (side link (SL) pilot)
channel and a D2D control signal (SL control) channel are mapped on
first-half symbols among symbols corresponding to Region "B" of a
5G physical channel configuration and a D2D data (SL data) channel
is mapped on second-half symbols may be used. Among symbols
corresponding to Region "B" of the 5G physical channel
configuration, one or more symbols of the head may be set as a
guard period, or a guard period may not be particularly set. FIGS.
3A, 3B, and 3C illustrate an example of a physical channel
configuration when one or more symbols of the head are set as a
guard period.
[0058] A physical channel configuration not including a guard
period may be described in the D2D physical channel configuration
to be described below, but does not intend that a guard period is
not included unless otherwise specified. A guard period may or may
not be set in D2D physical channel configurations to be described
below.
[0059] As illustrated in FIG. 3B, a feedback channel (SL feedback)
for feedback from the reception-side user equipment UEb to the
transmission-side user equipment UEa may be additionally mapped on
second-half symbols. Regarding the feedback, it is assumed that
ACK/NACK for HARQ of D2D data is fed back from the reception-side
user equipment UEb to the transmission-side user equipment UEa.
[0060] The number of symbols to which the feedback channel is
mapped may be equal to or different from the number of symbols of
the multi-use region.
[0061] As illustrated in FIG. 3C, the user equipment UE may set
transmission power in symbols corresponding to the multi-use region
to be low. The transmission power may be designated by an offset
value (an offset value from transmission power symbols other than
the multi-use region) predetermined or broadcasted using broadcast
information or may be designated by a transmission power parameter
indicating transmission power in the symbols corresponding to the
multi-use region.
(D2D Physical Channel Configuration (1-2))
[0062] FIGS. 4A and 4B are diagrams illustrating D2D physical
channel configuration (1-2) in the embodiment. Unlike FIGS. 3A, 3B,
and 3C, FIGS. 4A and 4B illustrate a D2D physical channel
configuration corresponding to a 5G physical channel configuration
not including a multi-use region in Region "B." In D2D physical
channel configuration (1-2), similarly to D2D physical channel
configuration (1-1), a D2D pilot signal channel and a D2D physical
control channel are mapped on first-half symbols among symbols
corresponding to Region "B" of the 5G physical channel
configuration and a D2D data (SL data) channel is mapped on
second-half symbols.
(D2D Physical Channel Configuration (1-3))
[0063] FIGS. 5A and 5B are diagrams illustrating D2D physical
channel configuration (1-3) in the embodiment. As illustrated in
FIGS. 5A and 5B, in this embodiment, a physical channel
configuration in which a D2D pilot signal channel and a D2D
physical control channel are mapped on first-half symbols among
symbols of the region obtained by excluding the multi-use region
from Region "B" of the 5G physical channel configuration and a D2D
physical data channel is mapped on second-half symbols may be used.
Similarly to FIGS. 3A, 3B, and 3C and FIGS. 4A and 4B, a feedback
channel for feedback from the reception-side user equipment UEb to
the transmission-side user equipment UEa may be additionally mapped
on the second-half symbols.
[0064] FIG. 5A illustrates a D2D physical channel configuration
when a feedback channel is not included and FIG. 5B illustrates a
D2D physical channel configuration when a feedback channel is
included.
(D2D Physical Channel Configuration (1-4))
[0065] FIGS. 6A and 6B are diagrams illustrating D2D physical
channel configuration (1-4) in the embodiment. As illustrated in
FIGS. 6A and 6B, it is also assumed in 5G that a downlink control
signal is transmitted using Region "B" like an enhanced physical
downlink control channel (EPDCCH) in the conventional LTE.
[0066] In this embodiment, when a downlink control signal is
transmitted using Region "B," a D2D physical channel configuration
in which a D2D pilot signal channel and a D2D physical control
channel are mapped on first-half symbols in whole Region "B" or the
region obtained by excluding the multi-use region from Region "B"
and a D2D physical data channel is mapped on second-half symbols
may also be used as in D2D physical channel configurations (1-1) to
(1-3).
[0067] FIG. 6A illustrates a D2D physical channel configuration
when the D2D pilot signal channel and the D2D physical control
channel are mapped on the first-half symbols in the region obtained
by excluding the multi-use region from Region "B." FIG. 6B
illustrates a D2D physical channel configuration when the D2D pilot
signal channel and the D2D physical control channel are mapped on
the first-half symbols among the symbols corresponding to Region
"B" and the D2D physical data channel is mapped on the second-half
symbols.
(D2D Physical Channel Configuration (1-5))
[0068] FIG. 7 is a diagram illustrating D2D physical channel
configuration (1-5) in the embodiment. In this embodiment, instead
of mapping the D2D pilot signal channel, the D2D physical control
channel, and the D2D physical data channel on one subframe, the D2D
pilot signal channel, the D2D physical control channel, and the D2D
physical data channel may be mapped using a plurality of subframes.
In the example illustrated in FIG. 7, the D2D pilot signal channel
and the D2D physical control channel are mapped on first two
subframes and the D2D physical data channel is mapped on
second-half of four subframes.
[0069] In D2D physical channel configuration (1-5), one media
access control protocol data unit (MAC PDU) may be divided and
mapped on a plurality of subframes. Since it is difficult to
transmit a D2D signal in a broadband in consideration of the
maximum transmission power and the coverage of the user equipment
UE, an amount of data which can be transmitted by one subframe is
limited. Accordingly, by transmitting one MAC PDU by a plurality of
subframes using D2D physical channel configuration (1-5), it is
possible to secure the coverage and to transmit a MAC PDU having a
large data size.
[0070] When D2D physical channel configuration (1-5) is applied,
all of a plurality of subframes to which the D2D physical control
channel is mapped may be considered as a physical side link control
channel (PSCCH) resource pool in the convention LTE, all of a
plurality of subframes to which the D2D physical data channel is
mapped may be considered as a physical side link shared channel
(PSSCH) resource pool, and the D2D control signal and the D2D data
may be time-hopped and frequency-hopped and repeatedly transmitted
in the resource pools similarly to the conventional D2D.
Accordingly, when D2D physical channel configuration (1-5) is
applied, it is possible to divert the conventional D2D interface
(corresponding to Rel-12) and to reduce a processing load of the
user equipment UE.
[0071] Allocation of the number of subframes to which the D2D
physical control channel is mapped and the number of subframes to
which the D2D physical data channel is mapped may be fixed or may
be dynamically selected by determination of the transmission-side
user equipment UEa.
[0072] A plurality of examples of the configuration of D2D physical
channel configuration (1) have been described above. By using D2D
physical channel configurations (1-1) to (1-4), it is possible to
transmit a D2D control signal and D2D data in one TTI and to
realize D2D communication with a delay lower than that in the
conventional LTE. When D2D physical channel configuration (1-5) is
used, it is possible to realize D2D communication with a delay
lower than that in the conventional LTE by mapping the D2D physical
control channel and the D2D physical data channel on subframes with
a cycle (for example, less than 40 ms) shorter than that in the
conventional LTE.
(Determination of Whether D2D Radio Resource is Available)
[0073] As described above, it is assumed that D2D physical channel
configuration (1) is mainly used when an operation of overlapping
5G radio resources and D2D radio resources. Therefore, in this
embodiment, the user equipment UE considers radio resources, which
are not allocated as the 5G radio resources in the range set as a
D2D resource pool among all radio resources allocated for 5G, as
D2D radio resources and transmits and receives a D2D signal. The
D2D resource pool may be broadcasted to the user equipment UE using
broadcast information as in the convention LTE or may be defined in
advance.
[0074] FIG. 8 is a diagram illustrating a relationship between the
D2D resource pool and the D2D physical channel configuration. As
illustrated in FIG. 8, the D2D resource pool is set to a specific
range among all the radio resources. A D2D physical channel is
mapped on a part other than Region "A" in the D2D resource pool.
The range of the D2D resource pool in FIG. 8 is an example. The D2D
resource pool in this embodiment may be set to a certain range
among all the radio resources or may be set to be periodically
repeated.
[0075] A specific processing sequence which is performed by the
user equipment UE will be described below. The user equipment UE
determines whether 5G radio resources are allocated to a whole or a
part of Region "B" (that is, whether a whole or a part of Region
"B" is allocated to transmission of DL data and transmission of UL
data) by monitoring Region "A" of the 5G physical channel
configuration for each subframe in the D2D resource pool, and
considers a whole or a part of Region "B" as the D2D radio
resources when 5G radio resources are not allocated to a whole or a
part of Region "B."
[0076] For example, the user equipment UE may determine whether 5G
radio resources are allocated to a whole or a part of Region "B" by
monitoring a specific radio resource (a search space) of Region
"A."
[0077] In this case, the base station eNB maps an identifier
indicating whether a whole or a part of Region "B" is allocated to
5G radio resources on the specific search space such that the user
equipment UE can easily ascertain the identifier. The base station
eNB may enable the user equipment UE to easily ascertain an
identifier by mapping the identifier indicating that a whole or a
part of Region "B" is D2D radio resources on the specific search
space. The identifier may be broadcasted using another subframe
(for example, a previous subframe or a subframe previous by several
subframes). By broadcasting the identifier using another subframe
in advance, it is possible to avoid an influence of a processing
delay which may occur in the user equipment UE. The specific
resource (the search space) may be quasi-statically broadcasted to
the user equipment UE using broadcast information or the like in
advance. The base station eNB may transmit an identifier indicating
that all of predetermined subframes are D2D radio resources using
another subframe (for example, a previous subframe or a subframe
previous by several subframes). In the predetermined subframes, the
user equipment UE can consider all the subframes including Region
"A" and Region "B" as the D2D radio resources.
[0078] For example, the user equipment UE may determine whether 5G
radio resources are allocated to a whole or a part of Region "B" by
monitoring control signals dedicated for user equipment UE included
in Region "A" for each subframe (that is, by monitoring Region "A"
in a whole band).
[0079] In this case, the base station eNB may not mask control
signals included in Region "A" with a cyclic redundancy check (CRC)
using a user equipment ID (UEID) to enable the user equipment UE
monitoring Region "A" to receive the control signals dedicated for
other user equipments UE.
[0080] For example, the user equipment UE may determine whether 5G
radio resources are allocated to a whole or a part of Region "B" by
determining whether reception power of a whole or a part of Region
"A" is equal to or less than a predetermined threshold value. In
order to prevent erroneous recognition due to measurement of
reception power of a control signal other than the control signal
indicating allocation of radio resources to Region "B" among the
control signals transmitted in Region "A," transmission resources
may be quasi-statically set to Region "A" for each control
signal.
[0081] For example, the user equipment UE may determine whether
Region "B" can be considered as D2D radio resources using explicit
broadcasting (such as an RRC signal or broadcast information) from
the base station eNB. For example, it may be determined that radio
resources for a random access channel, radio resources for a
synchronization signal, and radio resources for transmission of
broadcast information which are set in the broadcast information
cannot be used as the D2D radio resources.
[0082] For example, when a control signal transmitted in Region "A"
indicates radio resources mapped on Region "B" in another subframe,
the user equipment UE may determine whether Region "B" of another
subframe is considered as D2D radio resources by monitoring Region
"A."
[0083] Similarly to the transmission-side user equipment UEa, the
reception-side user equipment UEb monitors Region "A" and
determines whether 5G radio resources are allocated to a whole or a
part of Region "B." When it is determined that 5G radio resources
are not allocated to a whole or a part of Region "B," the
reception-side user equipment UEb monitors (waits for) a D2D signal
which may be transmitted in a whole or a part of Region "B." When
it is determined that 5G radio resources are allocated to a whole
of Region "B," the reception-side user equipment UEb may not
monitor Region "B." Accordingly, it is possible to suppress
consumption of a battery of the user equipment UE.
<D2D Physical Channel Configuration (2)>
[0084] D2D physical channel configuration (2) in this embodiment
will be described below. It is assumed that D2D physical channel
configuration (2) is mainly used to perform an operation in which
it is not necessary to consider interference with 5G radio
resources such as a carrier allocated as a carrier dedicated for
D2D communication or a carrier (for example, a carrier to which
dynamic TDD is not applied and in which a whole subframe is allowed
to be used as D2D radio resources) in which all radio resources can
be considered as D2D radio resources.
[0085] When D2D physical channel configuration (2) is applied, the
user equipment UE can transmit a D2D signal without determining
whether Region "A" may be considered as D2D radio resources by
monitoring Region "A." In a carrier to which D2D physical channel
configuration (2) is applied, all radio resources may be considered
as a D2D resource pool or a partial range of all the radio
resources may be set as the D2D resource pool. When a partial range
of all radio resources is set as a D2D resource pool, the user
equipment UE may transmit a D2D signal using D2D physical channel
configuration (2) within the range set as the D2D resource
pool.
[0086] FIGS. 9A and 9B are diagrams illustrating D2D physical
channel configuration (2) in the embodiment. As illustrated in
FIGS. 9A and 9B, in D2D physical channel configuration (2), a D2D
pilot signal (SL pilot) channel and a D2D control signal (SL
control) channel are mapped on first-half symbols in one TTI and a
D2D data (SL data) channel is mapped on second-half symbols.
[0087] FIG. 9A illustrates an example of a physical channel
configuration when the number of symbols per subframe (one TTI) is
set to be the same as the number of symbols in Region "B" in the 5G
physical channel configuration. By using the D2D physical channel
configuration illustrated in FIG. 9A, the user equipment UE can
perform a demodulation process common to D2D physical channel
configuration (1) when performing a demodulation process of a D2D
signal. That is, when an operation in which D2D physical channel
configuration (1) and D2D physical channel configuration (2) are
mixed is performed in a plurality of carriers, it is possible to
reduce a processing load of the user equipment UE.
[0088] FIG. 9B illustrates an example of D2D physical channel
configuration (2) when the number of symbols per subframe (one TTI)
is set to be the same as the number of symbols in a subframe in a
radio frame configuration which is used in 5G. By using D2D
physical channel configuration (2) illustrated in FIG. 9B, it is
possible to reduce a processing load of the user equipment UE when
transmitting a D2D control signal. In order to notify the user
equipment UE of a carrier to which D2D physical channel
configuration (2) is applied, the base station eNB may notify the
user equipment UE of carrier information indicating whether each of
a plurality of carriers allocated in the radio communication system
is a carrier in which a 5G radio resource and a D2D radio resource
are overlaid or a carrier which is allocated to be dedicated for
D2D communication (or a carrier in which all radio resources can be
considered as D2D radio resources). The user equipment UE may
select a D2D physical channel configuration which is used for the
D2D communication on the basis of the acquired carrier information.
Specifically, when the carrier for transmitting a D2D signal is a
carrier in which a 5G radio resource and a D2D radio resource are
overlaid, the user equipment UE transmits the D2D signal using D2D
physical channel configuration (1). When the carrier for
transmitting a D2D signal is a carrier which is allocated to be
dedicated for D2D communication (or a carrier in which all radio
resources can be considered as D2D radio resources), the user
equipment UE transmits the D2D signal using D2D physical channel
configuration (2).
[0089] D2D physical channel configuration (2) illustrated in FIG.
9B may be used for a carrier in which a 5G radio resource and a D2D
radio resource are overlaid. In this case, for example, a region to
which a D2D pilot signal channel and a D2D physical control channel
are mapped and Region "A" of the 5G physical channel configuration
may be multiplexed in a code division multiplexing (CDM)
manner.
[0090] D2D physical channel configuration (2) which is used for D2D
communication has been described above. By using D2D physical
channel configuration (2), it is possible to transmit the D2D
control signal and the D2D data for each TTI and to transmit and
receive data with a delay lower than that in the conventional
D2D.
<Modified Example of D2D Resource Pool>
[0091] In the conventional D2D (D2d of Rel-12), a resource pool is
set in a unit of subframes. On the other hand, in D2D physical
channel configuration (1) which is used in this embodiment, radio
resources are allocated in a unit of symbols instead allocating a
whole subframe to D2D radio resources. Therefore, in this
embodiment, when a D2D resource pool is set, the resource pool may
be set in a unit of symbols in addition to a unit of subframes.
More specifically, by adding information indicating symbol
positions in addition to information indicating a radio frame
number and a subframe number to information on a resource pool
which is notified of the user equipment UE using broadcast
information or the like, a start point and an end point of a
resource pool on the time axis may be indicated.
[0092] In this embodiment, it is assumed that orthogonal
frequency-division multiplexing (OFDM) is applied to transmission
of a D2D signal, and the D2D resource pool may be discontinuous on
the frequency axis. Single carrier transmission (of multi-clusters)
may be applied. In a resource pool in the conventional D2D (D2D of
Rel-12), two clusters can be allocated on the frequency axis, but
in this embodiment, a resource pool may be allocated to more
clusters. A resource pool which is discontinuous on the frequency
axis may be expressed by a bit map.
<<Frequency Multiplexing of 5G Radio Resources and D2D Radio
Resources>>
[0093] In the "(Determination of Whether D2D Radio Resource is
Available)," when 5G radio resources are not allocated to a whole
or a part of Region "B," a whole or a part of Region "B" is
considered as D2D radio resources.
[0094] When a part of Region "B" is considered as D2D radio
resources, 5G radio resources and D2D radio resources are
frequency-multiplexed in Region "B."
[0095] When 5G radio resources and D2D radio resources are
frequency-multiplexed, it is preferable that the user equipment UE
transmit a D2D signal not to interfere with 5G communication.
[0096] FIGS. 10A and 10B are diagrams illustrating a case in which
5G radio resources and D2D radio resources are
frequency-multiplexed. For example, as illustrated in FIG. 10A, it
is assumed that 5G radio resources and D2D radio resources are
frequency-multiplexed in Region "X" and Region "Y."
[0097] In this case, in order to suppress interference with 5G DL
data (or UL data), the user equipment UE may provide a guard band
in D2D radio resources and transmit a D2D signal. In this case, the
user equipment UE may change a bandwidth of the guard band when
Region "B" is allocated to transmission of DL data and when Region
"B" is allocated to transmission of UL data. The user equipment UE
may change (switch) the bandwidth of the guard band for each
subframe.
[0098] When a D2D signal is transmitted, the user equipment UE may
set transmission power of the D2D signal to be equal to or less
than transmission power of DL data (or UL data), for example, as
illustrated in FIG. 10B. In this case, the user equipment UE may
determine the transmission power of the D2D signal by transmission
power control (fractional TPC) based on a path loss acquired by
measuring a downlink pilot signal in Region "A" and a power control
command instructed from the base station eNB.
[0099] When Region "B" is allocated to transmission of DL data, the
user equipment UE may control the transmission power of the D2D
signal to be greater than that when Region "B" is allocated to
transmission of UL data. Accordingly, when Region "B" is allocated
to transmission of DL data, the reception-side user equipment UE
can control the reception power of the D2D signal to be equal to or
greater than a predetermined value.
[0100] The base station eNB may notify the user equipment UE of
transmission power of a D2D signal in a unit of subframes using a
downlink control signal transmitted in Region "A" and the user
equipment UE may determine the transmission power of the D2D signal
in accordance with the instruction.
[0101] The above-mentioned "(Determination of Whether D2D Radio
Resource is Available)," the user equipment UE is enabled to
consider a part of Region "B" as a D2D radio resource. In other
words, the user equipment UE can take charge of determination of a
radio resource range which is used to transmit a D2 signal.
Therefore, when 5G radio resources and D2D radio resources are
frequency-multiplexed, the base station eNB may explicitly
(forcibly) notify the user equipment UE of a radio resource range
in which a D2D signal can be transmitted using the downlink control
signal which is transmitted in Region "A" for each frame. By
causing the base station eNB to explicitly notify the user
equipment UE of the radio resource range, it is possible to clearly
separate a band used for 5G communication and a band used for D2D
communication and to further suppress interference with 5G.
[0102] The base station eNB may notify whether a multi-use region
(Flex) is included in the radio resource range in which a D2D
signal can be transmitted together when notifying the radio
resource in which a D2D signal can be transmitted. The downlink
control signal may be mapped on a specific resource (a search
space) in Region "A." The specific resource may be quasi-statically
notified to the user equipment UE using broadcast information or
the like in advance.
[0103] FIGS. 11A, 11B, and 11C are diagrams illustrating a method
of notifying radio resources in which a D2D signal can be
transmitted. The base station eNB may notify the user equipment UE
of "a radio resource region in which a D2D signal can be
transmitted" including a multi-use region (Flex) for each subframe
using a downlink control signal transmitted in Region "A" as
illustrated in FIG. 11A, or may notify the user equipment UE of "a
radio resource region in which a D2D signal can be transmitted" not
including a multi-use region (Flex) for each subframe as
illustrated in FIG. 11B.
[0104] The base station eNB may notify the user equipment UE of a
range of radio resources which are allocated to DL data (or UL
data) for each subframe using the downlink control signal
transmitted in Region "A" as illustrated in FIG. 11C. In this case,
the user equipment UE can determine that the radio resources in the
range which is not allocated to DL data (or UL data) are radio
resources in which can be transmitted a D2D signal.
[0105] The base station eNB may notify a range of radio resources
in granularity of symbols when notifying the range of radio
resources in which a D2D signal can be transmitted. As described
above, when Region "B" is used to transmit UL data, an uplink pilot
signal may be mapped on the head of Region "B." By performing
notification in granularity of symbols, the base station eNB can
notify the user equipment UE of the range of radio resources in
which a D2D signal can be transmitted to avoid a range to which an
uplink pilot signal is mapped. In this case, the user equipment UE
may consider a difference in the number of symbols which can be
used to transmit a D2D signal based on details of the downlink
control signal and may transmit the D2D signal using a symbol which
can be used in common to transmit the D2D signal. For example, when
the number of symbols which can be used to transmit a D2D signal
differs when an uplink pilot signal is mapped and when an uplink
pilot signal is not mapped, the D2D signal is always transmitted
with a configuration of a smaller number of symbols. In another
method, the D2D signal may be transmitted using a configuration of
a maximum number of symbols and symbols which cannot be used to
transmit a D2D signal may be punctured. For example, the user
equipment UE transmits the D2D signal using symbols which can be
used to transmit the D2D signal when the pilot signal is not
mapped, and performs puncture and transmits the D2D signal when an
uplink pilot signal is mapped.
<<Half-Duplex Communication Countermeasure>>
[0106] D2D employs half-duplex communication using a common
frequency band between the transmission-side user equipment UEa and
the reception-side user equipment UEb. Accordingly, a user
equipment UE which is transmitting a D2D signal cannot receive a
D2D signal transmitted from another user equipment UE. In the case
of D2D, since a partner user equipment UE to which data is
transmitted cannot be said to be always in a standby state, it is
necessary to cause the reception-side user equipment UE to easily
receive the D2D signal as much as possible in order to achieve a
decrease in delay in the D2D communication.
[0107] Therefore, a user equipment UE in this embodiment, may
transmit a D2D signal after ascertaining that another user
equipment UE does not transmit a D2D signal (a D2D physical data
channel is available). In another method, a user equipment UE in
this embodiment may repeatedly transmit the same D2D signal.
Hereinafter, a specific processing sequence thereof will be
described.
<Ascertainment of Availability of D2D Radio Resource>
[0108] FIG. 12 is a diagram illustrating a method of transmitting a
D2D signal after ascertaining availability of a D2D radio resource.
A user equipment UE may ascertain whether a D2D radio resource is
available by monitoring a radio resource region to which a D2D
physical control channel is mapped when transmitting a D2D signal,
and may transmit the D2D signal using a next subframe when it is
determined that the D2D radio resource is available (that another
user equipment UE does not transmit a D2D signal). The user
equipment UE may perform ascertainment of whether a D2D radio
resource is available on a plurality of continuous subframes, and
may transmit the D2D signal using a next subframe when the D2D
radio resources in the plurality of continuous subframes are
available. In the example illustrated in FIG. 12, the user
equipment UE performs ascertainment of whether a D2D radio resource
is available on two continuous subframes, and transmits a D2D
signal using a next subframe when it is determined that the D2D
radio resources in the two continuous subframes are available.
[0109] A method of ascertaining whether a D2D radio resource is
available will be more specifically described below. A user
equipment UE may ascertain whether a D2D radio resource is
available, for example, by performing carrier sensing in a radio
resource region to which a D2D physical control channel is mapped.
The carrier sensing is a process of determining whether a band in
which a D2D signal is to be transmitted is available or under use.
More specifically, the user equipment UE determines that the D2D
radio resource is under use when a reception level of a signal
received in the band to which the D2D physical control channel is
mapped is higher than a predetermined threshold value, and
determines that the D2D radio resource is available when the
reception level of the received signal is equal to or lower than
the predetermined threshold value.
[0110] The user equipment UE may detect a D2D control signal by
monitoring the radio resource region to which the D2D physical
control channel is mapped, and may ascertain whether the D2D radio
resource is available by checking radio resource allocation
information included in the D2D control signal.
[0111] When a D2D physical data channel (SL data) is divided into a
plurality of sub-channels on the time axis and the frequency axis,
the user equipment UE may ascertain whether the D2D radio resource
is available for each sub-channel.
[0112] When it is determined that the D2D radio resource is
available, the user equipment UE may transmit a D2D signal
continuously (in a burst manner) using a plurality of subframes
subsequent to a next subframe. For example, when it is ascertained
that the D2D radio resources in five continuous subframes are
available, the user equipment UE may continuously transmit a D2D
signal using eight subframes subsequent to the five subframes. The
eight subframes may be actually continuous frames or may be
subframes in which only subframes considered as the D2D radio
resource in the above-mentioned "(Determination of Whether D2D
Radio Resource is Available)" are continuous. Accordingly, it is
possible to enhance a possibility that a D2D signal will reach the
other user equipment UE.
[0113] In the radio communication system according to this
embodiment, the number of subframes which are used to ascertain
whether a D2D radio resource is available may be set to differ
depending on user equipments UE. The number of subframes may be
individually set for each user equipment UE using an RRC signal or
the like from the base station eNB.
[0114] Accordingly, an operation in which a certain user equipment
UE transmits a D2D signal using a next subframe when it is
ascertained that the D2D radio resource in three continuous
subframes is available and another user equipment UE transmits a
D2D signal using a next subframe when the D2D radio resource in
five continuous subframes is available can be realized, and the
timing at which each user equipment UE starts transmission of a D2D
signal can be randomized.
<Repeated Transmission>
[0115] A user equipment UE may repeatedly transmit the same D2D
signal when transmitting the D2D signal. When the same D2D signal
is repeatedly transmitted, the D2D signal may be repeatedly
transmitted using a subframe which is arbitrarily selected by the
user equipment UE among subframes available for the D2D radio
resource. The user equipment UE may repeatedly transmit a second or
subsequent D2D signal using a radio resource of the same band as
the radio resource in the frequency direction in the subframes
which has been first used to transmit the D2D signal. The user
equipment UE may repeatedly transmit a D2D signal on the basis of a
predetermined time/frequency hopping pattern.
(Repetition Window)
[0116] In this embodiment, a user equipment UE transmits a D2D
signal using a subframe which has been considered as a D2D radio
resource in the above-mentioned "(Determination of Whether D2D
Radio Resource is Available)." That is, when the user equipment UE
intends to repeatedly transmit the same D2D signal but the number
of radio resources (subframes) available as the D2D radio resource
is small, there is a possibility that a long time will be required
until a final D2D signal is transmitted after a first D2D signal is
transmitted.
[0117] Therefore, in this embodiment, a repetition window
indicating a range in which the same D2D signal is repeatedly
transmitted may be provided in advance and the user equipment UE
may repeatedly transmit the same D2D signal (the same D2D control
signal or/and the same D2D data) within only the repetition window.
The length of the repetition window is not particularly limited,
but a start point and an end point of a repetition window are
quasi-statically set in the same way as the D2D resource pool.
[0118] FIG. 13 is a diagram illustrating a method of repeatedly
transmitting a D2D signal. In the example illustrated in FIG. 13,
subframes 1-0 to 1-4 are set as a repetition window, and subframes
1-1 and 1-2 are subframes which are not available for D2D
communication (for example, allocated for 5G radio resources). In
this case, the user equipment UE can transmit the same D2D signal
using subframes 1-0, 1-3, and 1-4. That is, the user equipment UE
may repeatedly transmit the D2D signal using a subframe which is
arbitrarily selected among subframes 1-0, 1-3, and 1-4, or may
repeatedly transmit the D2D signal using a subframe corresponding
to a predetermined time/frequency hopping pattern among subframes
1-0, 1-3, and 1-4. In the example illustrated in FIG. 13, the user
equipment UE repeatedly transmits the same D2D signal using
subframe 1-0 and subframe 1-4.
[0119] A start point and an end point of a repetition window may be
explicitly set in a user equipment UE using broadcast information,
an RRC signal, or the like from the base station eNB by designating
a radio frame number, a subframe number, and a cycle.
[0120] A position of a reference subframe (a subframe position
specified by a radio frame number and a subframe number)
corresponding to a start point of a repetition window and a
time/frequency hopping pattern (for example, which is repeatedly
transmitted three times every other subframe) may be notified to a
user equipment UE using broadcast information, an RRC signal, or
the like from the base station eNB, and the user equipment UE may
recognize that subframes from the reference subframe to the final
subframe satisfying the time/frequency hopping pattern are a
repetition window.
[0121] A transmission-side user equipment UE may include
information indicating the start point and the end point of a
repetition window in a D2D control signal and may repeatedly
transmit the D2D signal. A reception-side user equipment UE
receiving the D2D signal can recognize the end point of the
repetition window with reference to the information.
(Time/Frequency Hopping Pattern)
[0122] As described above, when a D2D signal is repeatedly
transmitted, a user equipment UE may repeatedly transmit the D2D
signal on the basis of a predetermined time/frequency hopping
pattern.
[0123] FIG. 14 is a diagram illustrating a method of repeatedly
transmitting a D2D signal. For example, as illustrated in FIG. 14,
a user equipment UE may repeatedly transmit a D2D signal on the
basis of a predetermined time/frequency hopping pattern. In the
example illustrated in FIG. 14, a state in which the same D2D
signal is time/frequency-hopped and repeatedly transmitted using
subframes 1-0, 1-3, and 1-7 is illustrated.
[0124] In this embodiment, a time/frequency hopping pattern may be
shared by a transmission-side user equipment UEa and a
reception-side user equipment UEb and the reception-side user
equipment UEb may synthetically receive a plurality of D2D signals
which are repeatedly transmitted. Accordingly, the reception-side
user equipment UEb can enhance demodulation accuracy of the D2D
signal.
[0125] For example, in this embodiment, a time/frequency hopping
pattern may be prescribed for all subframes in a D2D resource pool
regardless of whether each subframe is a D2D radio resource, and
may be notified to a transmission-side user equipment UEa and a
reception-side user equipment UEb using broadcast information, an
RRC signal, or the like from the base station eNB.
[0126] In this case, the transmission-side user equipment UEa
additionally ascertains whether the subframe is a subframe
corresponding to the time/frequency hopping pattern notified in
advance when a D2D signal is transmitted and it is determined in
the above-mentioned "(Determination of Whether D2D Radio Resource
is Available)" that a subframe can be used to transmit the D2D
signal, and repeatedly transmits the D2D signal when the subframe
is a subframe corresponding to the time/frequency hopping pattern.
In this case, the user equipment UE does not transmit the D2D
signal using the subframe which is a subframe corresponding to the
time/frequency hopping pattern but cannot be used to transmit the
D2D signal.
[0127] The reception-side user equipment UEb monitors the D2D
signal on the basis of the previously notified time/frequency
hopping pattern, considers that the D2D signals received on the
basis of the time/frequency hopping pattern are the same D2D
signal, and tries synthetic reception. By prescribing the
time/frequency hopping pattern for all subframes in the D2D
resource pool in advance, the reception-side user equipment UEb can
correctly recognize whether received D2D signals are the same D2D
signal even when a subframe considered as a D2D radio resource is
erroneously recognized.
[0128] The time/frequency hopping pattern prescribed for all
subframes in the D2D resource pool may be defined as a plurality of
patterns. In this case, in order to enable the reception-side user
equipment UEb to ascertain which time/frequency hopping pattern is
applied, the transmission-side user equipment UEa may include
information indicating the applied time/frequency hopping pattern
in the D2D control signal.
[0129] For example, in this embodiment, the start point of the
time/frequency hopping pattern and the start point of the
repetition window may be prescribed to be equal to each other and
the time/frequency hopping pattern and the repetition window may be
notified in advance to the transmission-side user equipment UEa and
the reception-side user equipment UEb using broadcast information,
an RRC signal, or the like from the base station eNB. Since the
time/frequency hopping pattern is fixedly set regardless of whether
each subframe is used as a D2D radio resource, the reception-side
user equipment UEb can correctly recognize whether the received D2D
signals are the same D2D signal even when a subframe considered as
a D2D radio resource is erroneously recognized.
[0130] In another example, the start point of the time/frequency
hopping pattern may be arbitrarily determined by the
transmission-side user equipment UEa, and the transmission-side
user equipment UEa may include information indicating the applied
time/frequency hopping pattern in the D2D control signal. When the
D2D control signal can be received, the reception-side user
equipment UEb can determine radio resources to which the D2D
signal, which is repeatedly transmitted thereafter, is mapped.
[0131] Regarding the time/frequency hopping pattern, different
time/frequency hopping patterns may be prescribed for the D2D
control signal and the D2D data.
[0132] Instead of repeatedly transmitting the same D2D control
signal and the same D2D data for each subframe, the D2D control
signal may be first repeatedly transmitted and the D2D data may be
repeatedly transmitted after the repeated transmission of the D2D
control signal is completed. It is possible to divert the
time/frequency hopping pattern in the conventional D2D
(Rel-12).
[0133] In this embodiment, in order to enable the reception-side
user equipment UEb to recognize that the same D2D data is
repeatedly transmitted, the transmission-side user equipment UEa
may give an index indicating the same MAC PDU to a MAC header or
the like. Accordingly, the reception-side user equipment UEb
receiving a plurality of pieces of D2D data can specify whether the
received MAC PDU is a MAC PDU including repeated data or a MAC PDU
including new data. As a result, even when the time/frequency
hopping pattern is not shared in advance by the transmission-side
user equipment UEa and the reception-side user equipment UEb, the
reception-side user equipment UEb can recognize that the same D2D
data has been received.
[0134] In this embodiment, When a message (ACK) indicating that a
D2D signal can be correctly received from the reception-side user
equipment UEb via a feedback channel, the transmission-side user
equipment UEa may not repeatedly transmit the same D2D signal.
[0135] The method of allowing the reception-side user equipment UE
to receive a D2D signal as easily as possible has been described
above as a half-duplex communication countermeasure. The processing
sequence described in "<Ascertainment of Availability of D2D
Radio Resource>" and the processing sequence described in
"<Repeated Transmission>" may be appropriately combined. For
example, the processing sequence described in "<Ascertainment of
Availability of D2D Radio Resource>" may be applied to
transmission of a D2D control signal and the processing sequence
described in "<Repeated Transmission>" may be applied to
transmission of D2D data.
<Fail Safe>
[0136] In this embodiment, a user equipment UE transmits and
receives a D2D signal using a subframe which is considered as a D2D
radio resource in the above-mentioned "(Determination of Whether
D2D Radio Resource is Available)."
[0137] However, when a 5G radio resource is allocated but a user
equipment UE erroneously recognizes the 5G radio resource as a D2D
radio resource, it is assumed that 5G communication is affected due
to interference or the like.
[0138] Therefore, when a downlink control signal included in Region
"A" is not detected at the time of monitoring Region "A," the use
equipment UE may not consider the subframe as a D2D radio resource
(that is, does not transmit the D2D signal using the subframe). The
user equipment UE may not transmit the D2D signal within a range of
a repetition window associated with the subframe or within a
resource pool associated with the subframe in addition to the
subframe. Accordingly, for example, it is possible to reduce a
possibility that a user equipment UE present in an area having a
bad communication condition will erroneously recognize a 5G radio
resource as a D2D radio resource.
[0139] In another method, a base station eNB may allocate a D2D
radio resource to a predetermined subframe and may continuously
transmit a downlink control signal including information indicating
a position of the D2D radio resource allocated to the predetermined
subframe using a plurality of prescribed subframes (hereinafter
referred to as a "downlink control information report window"). A
user equipment UE may transmit a D2D signal using the predetermined
subframe only when the information is not received within the
plurality of prescribed subframes. The range of the downlink
control information report window may be notified from the base
station eNB to the user equipment UE in advance using broadcast
information, an RRC signal, or the like. A specific example thereof
will be described below with reference to the drawing.
[0140] FIG. 15 is a diagram illustrating a method of enhancing a
recognition rate of a D2D radio resource. A base station eNB, for
example, allocates D2D radio resources to five subframes ("Y" in
FIG. 15) and continuously transmits a downlink control signal
including information indicating positions of the D2D radio
resources allocated to the five subframes using five subframes
indicated by "X" in FIG. 15. A user equipment UE transmits a D2D
signal using the radio resources (resource blocks at indicated
positions) indicated by the information in the subframes ("Y" in
FIG. 15) to which the D2D radio resources are allocated only when
the information is received using one or more subframes of the five
subframes indicated by "X" in FIG. 15.
[0141] Accordingly, for example, it is possible to reduce a
possibility that a user equipment UE present in an area having a
bad communication condition will erroneously recognize a 5G radio
resource as a D2D radio resource and to reduce a possibility that a
transmission opportunity of a D2D signal will be lost because a
radio resource allocated for D2D is erroneously recognized as a 5G
radio resource.
<<Functional Configuration>>
[0142] An example of functional configurations of a user equipment
UE and a base station eNB that perform the operations of the
above-mentioned embodiment will be described below.
<User Equipment>
[0143] FIG. 16 is a diagram illustrating an example of a functional
configuration of a user equipment according to the embodiment. As
illustrated in FIG. 16, a user equipment UE includes a signal
transmission unit 101, a signal reception unit 102, a determination
unit 103, and an acquisition unit 104. FIG. 16 illustrates only
functional units, which are particularly associated with the
invention, in the user equipment UE and has functions, which are
not illustrated, for performing at least LTE-based operations. The
functional configuration illustrated in FIG. 16 is only an example.
The functional subdivision and the names of the functional units
are not particularly limited as long as the operations associated
with the embodiment can be performed.
[0144] The signal transmission unit 101 has a function of
generating various signals of a physical layer from a signal of an
upper layer to be transmitted from the user equipment UE and
wirelessly transmitting the generated signals. The signal
transmission unit 101 has a D2D signal transmitting function and a
cellular communication transmitting function. The signal
transmission unit 101 has a function of transmitting a D2D signal
on the basis of D2D physical channel configuration (1) or/and D2D
physical channel configuration (2).
[0145] The signal transmission unit 101 has a function of
transmitting a D2D signal on the basis of D2D physical channel
configuration (1) using Region "B" in a radio frame including a
region (Region "A") to which a downlink pilot signal and a downlink
control signal are mapped and a region (Region "B") to which
downlink user data or uplink data is mapped as a radio frame which
is shared by downlink communication and uplink communication with a
base station eNB in accordance with an instruction from the
determination unit 103.
[0146] The signal transmission unit 101 has a function of
transmitting a D2D signal using a radio frame in which a D2D
physical control channel and a D2D physical data channel are
time-multiplexed when the D2D signal is transmitted using a carrier
which is used only for D2D communication. The number of symbols in
the radio frame may be equal to the number of symbols in Region
"B."
[0147] The signal transmission unit 101 may transmit a D2D signal
with transmission power instructed from the base station eNB.
[0148] The signal transmission unit 101 may transmit a D2D signal
using a frequency band which is not allocated to the uplink
communication or downlink communication with the base station eNB
in Region "B" in accordance with an instruction from the
determination unit 103. The signal transmission unit 101 may
transmit a D2D signal using the frequency band with transmission
power instructed from the base station eNB.
[0149] The signal transmission unit 101 may transmit a D2D signal
in Region "B" when the determination unit 103 continuously
determines that the D2D signal can be transmitted a plurality of
times.
[0150] The signal transmission unit 101 may repeatedly transmit a
D2D signal on the basis of a predetermined hopping pattern. The
signal transmission unit 101 may repeatedly transmit a D2D signal
within a predetermined repetition window.
[0151] The signal reception unit 102 has a function of wirelessly
receiving various signals from another user equipment UE or a base
station eNB and acquiring a signal of an upper layer from the
received signals of the physical layer. The signal reception unit
102 has a D2D signal receiving function and a cellular
communication receiving function. The signal reception unit 102 has
a function of receiving a D2D signal on the basis of D2D physical
channel configuration (1) or/and D2D physical channel configuration
(2).
[0152] The determination unit 103 has a function of determining
whether a D2D signal can be transmitted in Region "B" by monitoring
Region "A" in a radio frame including a region (Region "A") to
which a downlink pilot signal and a downlink control signal are
mapped and a region (Region "B") to which downlink user data or
uplink data is mapped as a radio frame which is shared by downlink
communication and uplink communication with a base station eNB.
[0153] The determination unit 103 may determine that a D2D signal
can be transmitted in Region "B," when a control signal indicating
that Region "B" is allocated to uplink communication or downlink
communication between the base station eNB and the user equipment
UE is not included in Region "A" or when reception power of Region
"A" is equal to or less than a predetermined threshold value.
[0154] The determination unit 103 may determine that a D2D signal
can be transmitted in Region "B," when information indicating that
the D2D signal can be transmitted in a predetermined radio resource
of Region "B" is included in a downlink control signal transmitted
in Region "A." The determination unit 103 may instruct the signal
transmission unit 101 to transmit the D2D signal using the
predetermined radio resource indicated by the information.
[0155] The determination unit 103 may detect a frequency band in
Region "B" which is not allocated to uplink communication or
downlink communication between the base station eNB and the user
equipment UE. When it is detected that only a predetermined
frequency band in Region "B" is allocated to uplink communication
or downlink communication between the base station eNB and the user
equipment UE, the determination unit 103 may instruct the signal
transmission unit 101 to transmit a D2D signal in a frequency band
other than the predetermined frequency band.
[0156] The acquisition unit 104 has a function of acquiring carrier
information indicating whether each of a plurality of carriers
allocated in the radio communication system is a carrier which is
used in common to communication between the base station eNB and
the user equipment UE and D2D communication or a carrier which is
used for only D2D communication using broadcast information, an RRC
signal, or the like.
<Base Station>
[0157] FIG. 17 is a diagram illustrating an example of a functional
configuration of a base station according to the embodiment. As
illustrated in FIG. 17, the base station eNB includes a signal
transmission unit 201, a signal reception unit 202, a resource
allocation unit 203, and an instruction unit 204. FIG. 17
illustrates only functional units, which are particularly
associated with the embodiment of the invention, in the base
station eNB and also has a function of performing at least
LTE-based operations. The functional configuration illustrated in
FIG. 17 is only an example. The functional subdivision and the
names of the functional units are not particularly limited as long
as the operations associated with the embodiment can be
performed.
[0158] The signal transmission unit 201 has a function of
generating various signals of a physical layer from a signal of an
upper layer to be transmitted from the base station eNB and
wirelessly transmitting the generated signals. The signal reception
unit 202 has a function of wirelessly receiving various signals
from the user equipment UE and acquiring a signal of an upper layer
from the received signals of the physical layer.
[0159] The resource allocation unit 203 has a function of
allocating 5G radio resources and D2D radio resources.
[0160] The instruction unit 204 has a function of instructing a
variety of information associated with D2D communication to the
user equipment UE. Examples of the variety of information include a
power control command, information indicating a range of a
repetition window, a time/frequency hopping pattern, information
indicating a range of downlink control information report window,
and carrier information.
<Hardware Configuration>
[0161] The block diagrams (FIGS. 16 and 17) which are used above to
describe the embodiment illustrate blocks in units of functions.
The functional blocks (constituent units) are embodied in any
combination of hardware and/or software. Means for embodying the
functional blocks is not particularly limited. That is, the
functional blocks may be embodied by one unit which is physically
and/or logically coupled or may be embodied by two or more units
which are physically and/or logically separated and which are
connected directly and/or indirectly (for example, in a wired
and/or wireless manner).
[0162] For example, the user equipment UE and the base station eNB
in the embodiment of the invention may function as computers that
perform the processes of the communication method according to the
invention. FIG. 18 is a diagram illustrating an example of a
hardware configuration of the user equipment UE and the base
station eNB according to the invention. The user equipment UE and
the base station eNB described above may be physically configured
as a computer device including a processor 1001, a memory 1002, a
storage 1003, a communication device 1004, an input device 1005, an
output device 1006, and a bus 1007.
[0163] In the following description, a word "unit" may be referred
to as a circuit, a device, a unit, or the like. The hardware
configurations of the user equipment UE and the base station eNB
may include one or more units illustrated in the drawing or may not
include some units.
[0164] The functions of the user equipment UE and the base station
eNB are realized by causing hardware such as the processor 1001 and
the memory 1002 to read predetermined software (a program) and
causing the processor 1001 to perform computation and to control
communication of the communication device 1004 and reading and/or
writing of data in the memory 1002 and the storage 1003.
[0165] The processor 1001 controls the computer as a whole, for
example, by activating an operating system. The processor 1001 may
be constituted by a central processing unit (CPU) including an
interface with peripherals, a control unit, a calculation unit, a
register, and the like. For example, the signal transmission unit
101, the signal reception unit 102, the determination unit 103, and
the acquisition unit 104 of the user equipment UE and the signal
transmission unit 201, the signal reception unit 202, the resource
allocation unit 203, and the instruction unit 204 of the base
station eNB may be embodied by the processor 1001.
[0166] The processor 1001 reads a program (program codes), a
software module, or data from the storage 1003 and/or the
communication device 1004 to the memory 1002 and performs various
processes in accordance therewith. As the program, a program
causing a computer to perform at least a part of the operations
described above in the embodiment is used. For example, the signal
transmission unit 101, the signal reception unit 102, the
determination unit 103, and the acquisition unit 104 of the user
equipment UE and the signal transmission unit 201, the signal
reception unit 202, the resource allocation unit 203, and the
instruction unit 204 of the base station eNB may be embodied by a
control program which is stored in the memory 1002 and operated by
the processor 1001 or the other functional blocks may be similarly
embodied. Various processes described above have been described to
be performed by a single processor 1001, but may be simultaneously
or sequentially performed by two or more processors 1001. The
processor 1001 may be mounted as one or more chips. The program may
be transmitted from a network via an electric communication
line.
[0167] The memory 1002 is a computer-readable recording medium and
may be constituted, for example, by at least one of a read only
memory (ROM), an erasable programmable ROM (EPROM), an electrically
erasable programmable ROM (EEPROM), and a random access memory
(RAM). The memory 1002 may be referred to as a register, a cache,
or a main memory (a main storage unit). The memory 1002 can store a
program (program codes), a software module, or the like which can
be executed to perform the communication method according to the
embodiment of the invention.
[0168] The storage 1003 is a computer-readable recording medium and
may be constituted, for example, by at least one of an optical disc
such as a compact disc ROM (CD-ROM), a hard disk drive, a flexible
disk, a magneto-optical disk (such as a compact disk, a digital
versatile disk, or a Blu-ray (registered trademark) disk), a smart
card, a flash memory (such as a card, a stick, or a key drive), a
floppy (registered trademark) disk, and a magnetic strip. The
storage 1003 may be referred to as an auxiliary storage unit.
Examples of the recording medium may include a database including
the memory 1002 and/or the storage 1003, a server, and another
appropriate medium.
[0169] The communication device 1004 is hardware (a transceiver
device) that allows communication between computers via a wired
and/or wireless network and is referred to as, for example, a
network device, a network controller, a network card, or a
communication module. For example, the signal transmission unit 101
and the signal reception unit 102 of the user equipment UE and the
signal transmission unit 201 and the signal reception unit 202 of
the base station eNB may be embodied by the communication device
1004.
[0170] The input device 1005 is an input device (such as a
keyboard, a mouse, a microphone, a switch, a button, or a sensor)
that receives an input from the outside. The output device 1006 is
an output device (such as a display, a speaker, or an LED lamp)
that performs outputting to the outside. The input device 1005 and
the output device 1006 may be configured as a unified body (such as
a touch panel).
[0171] The units such as the processor 1001 and the memory 1002 are
connected to each other via the bus 1007 for transmitting and
receiving information. The bus 1007 may be constituted by a single
bus or may be configured by different buses between the units.
[0172] The user equipment UE and the base station eNB may be
configured to include hardware such as a microprocessor, a digital
signal processor (DSP), an application specific integrated circuit
(ASIC), a programmable logic device (PLD), or a field programmable
gate array (FPGA), or a part or all of the functional blocks may be
embodied by the hardware. For example, the processor 1001 may be
mounted as at least one hardware module.
<<Summary>>
[0173] According to the above-mentioned embodiment, there is
provided a user equipment in a radio communication system that
supports D2D communication. The user equipment includes a
determination unit that receives a first region in a radio frame,
which is commonly used for downlink communication and uplink
communication with a base station and includes the first region to
which a downlink pilot signal and a downlink control signal are to
be mapped and a second region to which downlink user data or uplink
data is to be mapped, to determine whether a D2D signal is
transmittable using the second region; and a transmission unit that
transmits the D2D signal using the second region in the radio frame
where a D2D physical control channel and a D2D physical data
channel are time-multiplexed when the determination unit determines
that the D2D signal is transmittable. According to the user
equipment UE, it is possible to provide a technology that enables
D2D communication with a low delay.
[0174] The determination unit may determine that the D2D signal is
transmittable using the second region when the first region does
not include a control signal indicating that the second region is
allocated to the uplink communication or the downlink communication
with the base station or when reception power of the first region
is less than or equal to a predetermined threshold value.
Accordingly, it is possible to perform D2D communication, for
example, using a radio resource to which no 5G radio resource is
allocated. That is, it is possible to multiplex a 5G radio resource
and a D2D communication radio resource.
[0175] The transmission unit may transmit the D2D signal using a
frequency band other than a predetermined frequency band in the
second region when only the predetermined frequency band is
allocated to the uplink communication or the downlink communication
with the base station. Accordingly, it is possible to
frequency-multiplex 5G communication and D2D communication in the
same band.
[0176] The transmission unit may transmit the D2D signal with
transmission power specified by the base station using the
frequency band other than the predetermined frequency band.
Accordingly, when 5G communication and D2D communication are
frequency-multiplexed in the same band, it is possible to suppress
interference between the 5G communication and the D2D
communication. Since the interference is suppressed, it is possible
to improve communication quality.
[0177] The transmission unit may transmit the D2D signal using the
second region when the determination unit determines multiple times
in succession that the D2D signal is transmittable. Accordingly, it
is possible to transmit a D2D signal at a timing where it is highly
unlikely that another user equipment UE is transmitting a D2D
signal and to avoid an influence of half-duplex communication as
much as possible. It is also possible to increase the possibility
that a D2D signal reaches a reception-side user equipment UE.
[0178] According to the above-mentioned embodiment, there is
provided a user equipment in a radio communication system that
supports D2D communication. The user equipment includes an
acquisition unit that acquires carrier information indicating
whether each of multiple carriers allocated to the radio
communication system is used commonly for communication between a
base station and the user equipment and D2D communication or used
only for the D2D communication; and a transmission unit that when a
D2D signal is to be transmitted using a carrier used only for the
D2D communication, transmits the D2D signal using a radio frame
where a D2D physical control channel and a D2D physical data
channel are time-multiplexed. With this user equipment UE, it is
possible to provide a technology that enables D2D communication
with a low delay.
[0179] The number of symbols of the radio frame may be equal to the
number of symbols corresponding to a region to which the downlink
user data or the uplink data is mapped in a radio frame used in a
carrier where communication between the base station and the user
equipment is performed. Accordingly, when physical channel
configuration (1) and physical channel configuration (2) are mixed
in multiple carriers, it is possible to reduce the processing load
of the user equipment UE.
[0180] The transmission unit may repeatedly transmit the D2D signal
based on a predetermined hopping pattern. Accordingly, it is
possible to avoid an influence of half-duplex communication as much
as possible. It is also possible to enhance the possibility that a
D2D signal reaches a reception-side user equipment UE.
[0181] According to the above-mentioned embodiment, there is
provided a communication method performed by a user equipment in a
radio communication system that supports D2D communication. The
communication method includes receiving a first region in a radio
frame, which is commonly used for downlink communication and uplink
communication with a base station and includes the first region to
which a downlink pilot signal and a downlink control signal are to
be mapped and a second region to which downlink user data or uplink
data is to be mapped, and thereby determining whether a D2D signal
is transmittable using the second region; and transmitting the D2D
signal using the second region in the radio frame where a D2D
physical control channel and a D2D physical data channel are
time-multiplexed when it is determined in the determining that the
D2D signal is transmittable. According to the communication method,
it is possible to provide a technology that enables D2D
communication with a low delay.
[0182] According to the above-mentioned embodiment, there is
provided a communication method performed by a user equipment in a
radio communication system that supports D2D communication. The
communication method includes acquiring carrier information
indicating whether each of multiple carriers allocated to the radio
communication system is used commonly for communication between a
base station and the user equipment and D2D communication or used
only for the D2D communication; and when a D2D signal is to be
transmitted using a carrier used only for the D2D communication,
transmitting the D2D signal using a radio frame where a D2D
physical control channel and a D2D physical data channel are
time-multiplexed. According to the communication method, it is
possible to provide a technology that enables D2D communication
with a low delay.
<Complement of Embodiment>
[0183] The D2D physical control channel may be a PSCCH. The D2D
physical data channel may be a PSSCH. The D2D control signal may be
side link control information (SCI). The control signal and the
control information may be used in the same meaning.
[0184] The configuration of the devices (user equipment
[0185] UE/base station eNB) described in the embodiment of the
invention may have a configuration in which the devices include a
CPU and a memory and which is embodied by causing the CPU
(processor) to execute a program, may have a configuration which is
embodied by hardware such as a hardware circuit having logics of
the processing described in the embodiment, or may have a
configuration in which a program and hardware are mixed.
[0186] While embodiments of the invention have been described
above, the invention disclosed herein is not limited to the
embodiments and it will be understood by those skilled in the art
that various modifications, corrections, alternatives,
substitutions, and the like can be made. While description has been
made using specific numerical value examples for the purpose of
promoting understanding of the invention, such numerical values are
only simple examples and arbitrary appropriate values may be used
unless otherwise specified. The sorting of items in the above
description is not essential to the invention, details described in
two or more items may be combined for use if necessary, or details
described in a certain item may be applied to details described in
another item (unless incompatible). Boundaries between functional
units or processing units in the functional block diagrams cannot
be said to be necessarily correspond to boundaries of physical
components. Operations of a plurality of functional units may be
physically performed by one component, or an operation of one
functional unit may be physically performed by a plurality of
components. The sequences and the flowcharts described above in the
embodiment may be changed in the order as long as they are not
incompatible with each other. For the purpose of convenience of
explanation, while a user equipment UE and a base station eNB have
been described above with reference to functional block diagrams,
such devices may be embodied by hardware, by software, or by
combination thereof. Software which is executed by a processor of
the user equipment UE and software which is executed by a processor
of the base station eNB in the embodiments of the invention may be
stored in an appropriate storage medium such as a random access
memory (RAM), a flash memory, a read only memory (ROM), an EPROM,
an EEPROM, a register, a hard disk (HDD), a removable disk, a
CD-ROM, a database, or a server.
[0187] In the embodiment, Region "A" is an example of the first
region. Region "B" is an example of the second region.
EXPLANATION OF REFERENCE NUMERALS
[0188] eNB base station
[0189] UE user equipment
[0190] 101 signal transmission unit
[0191] 102 signal reception unit
[0192] 103 determination unit
[0193] 104 acquisition unit
[0194] 201 signal transmission unit
[0195] 202 signal reception unit
[0196] 203 resource allocation unit
[0197] 204 instruction unit
[0198] 1001 processor
[0199] 1002 memory
[0200] 1003 storage
[0201] 1004 communication device
[0202] 1005 input device
[0203] 1006 output device
* * * * *
References