CN104812052B

CN104812052B - Transmission method and system, sending end and receiving end of D2D communication synchronization signal

Info

Publication number: CN104812052B
Application number: CN201410036812.1A
Authority: CN
Inventors: 袁明; 夏树强; 吴栓栓; 袁弋非; 杨瑾
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2014-01-24
Filing date: 2014-01-24
Publication date: 2020-01-10
Anticipated expiration: 2034-01-24
Also published as: CN104812052A; WO2015109433A1

Abstract

The invention discloses a transmission method and a system, a sending end and a receiving end of a D2D communication synchronization signal, wherein the system comprises the following steps: a transmitting end and a receiving end. The sending end comprises a configuration module and a sending module, and the receiving end comprises a configuration module and a receiving module, wherein the configuration module is used for acquiring time-frequency resources preconfigured by the network side through interaction with the network side, the preconfigured time-frequency resources refer to n groups of synchronization resources reserved on a device-to-device D2D transmission bandwidth and used for bearing synchronization signals, and the frequency domain positions of the groups of synchronization resources in a subframe are determined by using D2D synchronization signals D2DSS located on each group of synchronization resources, wherein n is a positive integer; a sending module, configured to send the D2DSS on a time-frequency resource preconfigured on the network side; a receiving module, configured to receive the D2DSS on a time-frequency resource preconfigured on the network side. The invention solves the problem of synchronization between equipment under various out-of-coverage scenes.

Description

Transmission method and system, sending end and receiving end of D2D communication synchronization signal

Technical Field

The present invention relates to the field of wireless communications, and in particular, to a Device-to-Device (D2D) communication synchronization signal transmission method and system, a transmitting end, and a receiving end.

Background

Cellular communication systems have developed wireless communication technology in a vigorous fashion due to the reuse of limited spectrum resources. In a cellular system, when there is a service to be transmitted between two User equipments (User equipments, abbreviated as UEs), service data from a User Equipment 1 (UE 1) to a User Equipment 2 (UE 2) is first transmitted to a base station 1 over an air interface, the base station 1 transmits the User data to a base station 2 over a core network, and the base station 2 transmits the service data to a UE2 over the air interface. Similar processing flows are adopted for traffic data transmission from UE2 to UE 1. As shown in fig. 1, when UE1 and UE2 are located in the same cell, although base station 1 and base station 2 are the same site, one data transmission still consumes two radio spectrum resources.

It follows that the above-described cellular communication method is clearly not an optimal communication means if the user equipment 1 and the user equipment 2 are located in the same cell and are relatively close together. In fact, as mobile communication services are diversified, for example, social networks, electronic payments, and the like are applied to wireless communication systems more and more widely, so that the service transmission demand between close-range users is increased. Therefore, a Device-to-Device (D2D) communication mode is receiving increasing attention. As shown in fig. 2, D2D means that the service data is not forwarded through the base station, but is directly transmitted to the target user equipment through an air interface by the source user equipment. This communication mode is different from that of the conventional cellular system. For users of short-range communication, D2D not only saves wireless spectrum resources, but also reduces data transmission pressure of the core network. The D2D communication based on the cellular network is a novel technology for directly communicating among a plurality of terminal devices supporting the D2D function under the control of a system, can reduce the occupation of system resources, increase the spectrum efficiency of the cellular communication system, reduce the transmitting power consumption of the terminal and save the network operation cost to a great extent.

In D2D Communication, the receiving end of D2D service data may be a single UE or multiple UEs, that is, D2D Communication may be Unicast (single) Communication, Broadcast (Broadcast) Communication, Multicast (Group host or Group Communication), or Multicast (Multicast) Communication. In consideration of the D2D communication scheme, support for the above communication modes needs to be considered.

Long term evolution (Long term evolution, LTE for short), Advanced Long term evolution (LTE-a) and International mobile telecommunications (IMT-Advanced) systems are based on Orthogonal Frequency Division Multiplexing (OFDM) technology, and OFDM systems are time-Frequency two-dimensional data formats. One 10ms radio frame (frame) consists of 10 subframes and 1 subframe (subframe) consists of 2 consecutive slots (slots), i.e. subframe i comprises slots 2i and 2i + 1. When Normal cyclic prefix (Normal CP) is used, 1 downlink subframe is composed of 14 OFDM symbols, and 1 uplink subframe is composed of 14 SC-FDMA (single carrier-Frequency Division Multiple Access) symbols; when cp (extended cp) is extended, 1 downlink subframe is composed of 12 OFDM symbols, and 1 uplink subframe is composed of 12 SC-FDMA symbols.

One Resource Block (RB) is composed of 12 subcarriers in succession in the frequency domain and all OFDM/SC-FDMA symbols in 1 slot in succession in the time domain; one Resource block pair (RB pair for short) is composed of 12 subcarriers consecutive in the frequency domain and all OFDM/SC-FDMA symbols within 1 subframe consecutive in the time domain. The Resource corresponding to one subcarrier on each OFDM/SC-FDMA symbol is called a Resource Element (RE).

In LTE/LTE-a cellular communication, cell search is a very critical step in mobile communication, which is a prerequisite for a terminal to establish a communication link with a base station. No matter the terminal is initially powered on in the serving cell or performs cell handover in the communication process, the connection needs to be established with the base station through the cell search process. The cell search process is mainly to make the terminal and the cell obtain time synchronization and frequency synchronization and obtain the physical cell ID, system bandwidth and other cell broadcast information. Generally, a terminal first obtains time synchronization and frequency synchronization through a synchronization signal, and then obtains related information of a current cell, such as bandwidth, cell ID, frame clock information, cell antenna configuration, CP length, and the like.

In D2D communication, a first premise of data transmission between a source user equipment and a target user equipment is to implement time-frequency Synchronization at both transmitting and receiving ends, and at present, only one rough Synchronization process is designed for D2D Synchronization, that is, after a D2D receiving end acquires time-frequency Synchronization with a transmitting end according to a device-to-device Synchronization Signal (D2D Synchronization Signal, abbreviated as D2 DSS) transmitted by a D2D transmitting end, it further receives a Physical device-to-device Synchronization Channel (Physical D2D Synchronization Channel, abbreviated as PD2 DSCH) transmitted by the D2D transmitting end, so as to obtain more detailed system information at the D2D transmitting end and control information related to subsequent data reception. However, there is no specific implementation details, including how the D2DSS and the PD2DSCH are transmitted, the association between the D2DSS and the PD2DSCH, etc. Since the D2D communication uses uplink resources (i.e. uplink frequency band of FDD or uplink subframe of TDD) for transmission, the design of synchronization procedure and synchronization signaling between D2D UEs is very different from that in LTE/LTE-a system.

Disclosure of Invention

The technical problem to be solved by the present invention is to provide a transmission method and system, a transmitting end and a receiving end for D2D communication synchronization signals, which solve the synchronization problem between devices in various coverage scenarios (including in-coverage, out-coverage and half-coverage scenarios).

In order to solve the above technical problem, the present invention provides a method for transmitting a device-to-device synchronization signal, including:

a device-to-device D2D sending end sends a D2D synchronization signal D2DSS on a time frequency resource pre-configured on a network side; the preconfigured time-frequency resource refers to n groups of synchronization resources reserved on a D2D transmission bandwidth and used for carrying synchronization signals, and determines a frequency domain position of each group of synchronization resources in a subframe by using a D2DSS located on each group of synchronization resources, where n is a positive integer.

Further, the D2DSS includes: the D2D primary synchronization signal PD2DSS and/or the D2D secondary synchronization signal SD2 DSS;

the n groups of synchronization resources for carrying synchronization signals include:

in the frequency domain, respectively consisting of

Each data block RB consists of i ═ 1, 2.., n;

in the time domain, the PD2DSS occupies p SC-FDMA symbols, and the SD2DSS occupies q SC-FDMA symbolsP and q are each a positive integer of 1 or more,

the number of RBs occupied by the ith synchronization resource is a positive integer less than or equal to 6.

Further, the determining the frequency domain position of each group of synchronization resources in the subframe by using the D2DSS located on the synchronization resource group includes:

the time domain positions of the PD2DSS and the SD2DSS positioned on each group of synchronous resources in the subframe uniquely correspond to the frequency domain positions of the synchronous resources in the subframe, and different time domain positions correspond to different frequency domain positions.

Further, the method further comprises: when the D2DSS is sent, the PD2DSS and the SD2DSS carry a root sequence;

the determining the frequency domain position of each group of synchronization resources in the subframe by using the D2DSS located on the synchronization resources comprises:

the root sequences of the PD2DSS and SD2DSS located on each set of synchronization resources correspond uniquely to the frequency domain positions of the synchronization resources in the subframe, with different root sequences corresponding to different frequency domain positions.

Further, the frequency domain positions of the n groups of synchronization resources for carrying synchronization signals in the subframe include:

in a subframe, the n groups of synchronization resources for carrying synchronization signals are respectively arranged on the frequency domain

With bilateral symmetry as centre

A resource unit RE, wherein i 1,2, n,

the transmission bandwidth of D2D occupies the total number of resource blocks RB,

for in each RBTotal number of sub-carriers involved.

when n is 1, there are only 1 set of synchronization resources whose frequency domain position in the subframe is on one of: at the centre of the D2D transmission bandwidthStarting from the upper band edge of the D2D transmission bandwidth on a RB

Starting at the lower band edge of the D2D transmission bandwidth and over one RB

RB, wherein i ═ 1;

when n is 2, there are 2 sets of synchronization resources whose frequency domain positions in the subframe are on any two of: at the centre of the D2D transmission bandwidth

Starting from the upper band edge of the D2D transmission bandwidth on a RB

RB, wherein i ═ 1, 2;

when n is 3, there are 3 sets of synchronization resources whose frequency domain positions in the subframe are respectively at the center of the D2D transmission bandwidth and starting from the upper/lower two band edges of the D2D transmission bandwidthAnd RB, wherein i is 1,2 and 3.

Further, when p ═ q ═ 1, the time domain positions of the PD2DSS and the SD2DSS in the subframe specifically include:

the PD2DSS is arranged on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is arranged on the SC-FDMA symbol behind the PD2DSS, and the interval between the two is any number of SC-FDMA symbols in 0-5; alternatively, the first and second electrodes may be,

the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is located on the SC-FDMA symbol before the PD2DSS, and the interval between the SD2DSS and the SC-FDMA symbol is any number of SC-FDMA symbols in 1-4; alternatively, the first and second electrodes may be,

the SD2DSS is arranged on the last SC-FDMA symbol of the first half slot of the subframe, the PD2DSS is arranged on the SC-FDMA symbol before the SD2DSS, and the interval between the SD2DSS and the SC-FDMA symbol is any number of SC-FDMA symbols in 0-4; alternatively, the first and second electrodes may be,

the SD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the PD2DSS is located on the SC-FDMA symbol after the SD2DSS, and the interval between the SD2DSS and the SC-FDMA symbol is 0, 1, 3, 4 or 5; alternatively, the first and second electrodes may be,

the symbol positions occupied by the PD2DSS and the SD2DSS are SC-FDMA symbols uniformly shifted leftwards by any number of symbols in 1-4 on the basis of the time domain position of the D2DSS in the LTE; alternatively, the first and second electrodes may be,

the symbol positions occupied by the PD2DSS and the SD2DSS are SC-FDMA symbols uniformly shifted to the right by any number of symbols in 2-6 on the basis of the time domain position of the D2DSS in the LTE.

Further, before transmitting the D2DSS, the method further comprises:

the D2D sending end and the D2D receiving end negotiate and agree to send and receive the D2DSS on the time frequency resource pre-configured on the same network side.

Further, the sending end of D2D sends D2DSS on a time-frequency resource preconfigured by the network side, including:

in an out-of-coverage scenario, the D2D sending end monitors the n sets of synchronization resources for carrying synchronization signals, if there is an idle synchronization resource, selects an idle synchronization resource to send the D2DSS on a time-frequency resource preconfigured on the network side, and if there is no idle synchronization resource, waits for re-monitoring at the next time;

or, in an in-coverage/semi-coverage scenario, the D2D sending end sends the D2DSS on a time-frequency resource preconfigured by the network side using a synchronization resource indicated by the network side.

In order to solve the above technical problem, the present invention further provides a device-to-device synchronization signal transmission method, including:

the device-to-device D2D receiving end receives the D2D synchronization signal D2DSS on the time frequency resource pre-configured on the network side; the preconfigured time-frequency resource refers to n groups of synchronization resources reserved on a D2D transmission bandwidth and used for carrying synchronization signals, and determines a frequency domain position of each group of synchronization resources in a subframe by using a D2DSS located on each group of synchronization resources, where n is a positive integer.

Further, the D2DSS includes: a D2D primary synchronization signal PD2DSS and a D2D secondary synchronization signal SD2 DSS;

in the frequency domain, respectively consisting of

RB consists of i ═ 1, 2.., n;

in the time domain, the PD2DSS occupies p SC-FDMA symbols, the SD2DSS occupies q SC-FDMA symbols, p and q are positive integers greater than or equal to 1,

Further, the PD2DS and the SD2DSS carry root sequences;

the root sequences of the PD2DSS and/or SD2DSS located on each set of synchronization resources correspond uniquely to the frequency domain positions of the synchronization resources in the subframe, with different root sequences corresponding to different frequency domain positions.

Further, prior to receiving the D2DSS, the method further comprises:

and the D2D receiving end and the D2D transmitting end negotiate and agree to receive and transmit the D2DSS on the time frequency resource pre-configured on the same network side.

Further, the receiving end of D2D receives D2DSS on a time-frequency resource pre-configured by the network side, including:

the D2D receiving end performs full-band scanning in the range of the D2D transmission frequency band to acquire PD2DSS on n groups of synchronous resources;

and for each group of synchronous resources, searching the SD2DSS forwards or backwards on the basis of the time domain position of the PD2DSS, and determining the corresponding frequency domain position of the synchronous resources in the subframe according to the time domain positions of the PD2DSS and the SD2DSS in the subframe.

the D2D receiving end performs full-band scanning in the range of the D2D transmission frequency band to acquire PD2DSS on n groups of synchronous resources, and the PD2DSS carries a root sequence;

and for each group of synchronous resources, receiving the SD2DSS carrying the root sequence, and determining the corresponding frequency domain position of the synchronous resources in the subframe according to the root sequence carried by the PD2DSS and/or the root sequence carried by the SD2 DSS.

In order to solve the above technical problem, the present invention further provides a sending end of a device-to-device synchronization signal, including:

a configuration module, configured to acquire, through interaction with a network side, a time-frequency resource preconfigured by the network side, where the preconfigured time-frequency resource refers to n groups of synchronization resources reserved on a device-to-device D2D transmission bandwidth and used for carrying synchronization signals, and determine a frequency domain position of each group of synchronization resources in a subframe by using a D2D synchronization signal D2DSS located on each group of synchronization resources, where n is a positive integer;

and the sending module is used for sending the D2DSS on a time-frequency resource pre-configured by the network side.

in the frequency domain, respectively consisting of

Each data block RB consists of i ═ 1, 2.., n;

the root sequences of PD2DSS and SD2DSS positioned on each group of synchronous resources uniquely correspond to the frequency domain positions of the synchronous resources in the subframe, and different root sequences correspond to different frequency domain positions;

the sending module is further configured to send the D2DSS, where the PD2DSS and the SD2DSS carry a root sequence.

With bilateral symmetry as centre

A resource unit RE, wherein i 1,2, n,

as the total number of subcarriers contained in each RB.

when n is 1, there are only 1 set of synchronization resources whose frequency domain position in the subframe is on one of: at the centre of the D2D transmission bandwidth

Starting from the upper band edge of the D2D transmission bandwidth on a RB

RB, wherein i ═ 1;

when n is 2, there are 2 sets of synchronization resources whose frequency domain positions in the subframe are on any two of: at the centre of the D2D transmission bandwidthStarting from the upper band edge of the D2D transmission bandwidth on a RB

RB, wherein i ═ 1, 2;

when n is 3, there are 3 sets of synchronization resources whose frequency domain positions in the subframe are respectively at the center of the D2D transmission bandwidth and starting from the upper/lower two band edges of the D2D transmission bandwidth

And RB, wherein i is 1,2 and 3.

Further, the configuration module is further configured to negotiate with a D2D receiving end to agree to send and receive the D2DSS on a time-frequency resource preconfigured on the same network side before sending the D2 DSS.

Further, the sending end further includes:

a resource selection module, configured to monitor the n groups of synchronization resources for carrying synchronization signals in a non-coverage scenario, select an idle synchronization resource to notify the sending module to send the D2DSS on a time-frequency resource preconfigured on the network side if there is an idle synchronization resource, and wait for re-monitoring at a next time if there is no idle synchronization resource;

or, in an in-coverage/semi-coverage scenario, the D2D sending end uses a synchronization resource indicated by a network side to notify the sending module to send the D2DSS on a time-frequency resource preconfigured by the network side.

In order to solve the above technical problem, the present invention further provides a device-to-device synchronization signal receiving end, including:

a receiving module, configured to receive the D2DSS on a time-frequency resource preconfigured on the network side.

in the frequency domain, respectively consisting of

RB consists of i ═ 1, 2.., n;

the root sequences of the PD2DSS and/or SD2DSS positioned on each group of synchronous resources uniquely correspond to the frequency domain positions of the synchronous resources in the subframe, and different root sequences correspond to different frequency domain positions;

the receiving module is further configured to, when receiving the D2DSS, the PD2DS and the SD2DSS carry a root sequence.

Further, the configuration module is further configured to negotiate with the D2D sender to agree to receive and send the D2DSS on a time-frequency resource preconfigured on the same network side before receiving the D2 DSS.

Further, the receiving module is configured to receive a D2DSS on a time-frequency resource preconfigured by the network side, and includes:

scanning the full frequency band within the range of the D2D transmission frequency band to obtain PD2DSS on n groups of synchronous resources;

scanning the full frequency band within the range of a D2D transmission frequency band to obtain PD2DSS on n groups of synchronous resources, wherein the PD2DSS carries a root sequence;

In order to solve the above technical problem, the present invention further provides a device-to-device synchronization signal transmission system, including: a transmitting end as described above and a receiving end as described above.

Compared with the prior art, the transmission method and system, the sending end and the receiving end of the D2D communication synchronization signal provided by the invention mainly solve the synchronization problem between the devices in various coverage scenes (including in-coverage, out-coverage and semi-coverage scenes).

Drawings

FIG. 1 is a diagram of cellular communications in the prior art when UEs are located in the same base station cell;

fig. 2 is a schematic diagram of a preferred D2D communication system in the prior art;

fig. 3a to f are schematic time-domain positions of a PD2DSS and the SD2DSS in a subframe when p ═ q ═ 1 is preferred in the embodiment;

fig. 4a is a schematic time domain position diagram of a PD2DSS and the SD2DSS in a subframe when p = q =2 in the embodiment;

fig. 4b is a schematic time domain position diagram of the PD2DSS and the SD2DSS in a subframe when p =1 and q =2 in the embodiment;

fig. 5 is a flowchart illustrating a specific process of the D2D sending end sending D2DSS on a time-frequency resource pre-configured on a network side in the embodiment;

fig. 6 is a flowchart illustrating a specific process of receiving D2DSS by the receiving end of D2D on a time-frequency resource pre-configured on the network side in the embodiment;

fig. 7 is a flowchart illustrating a specific process of receiving D2DSS by the receiving end of D2D on a time-frequency resource pre-configured on the network side in the embodiment;

FIG. 8 is a block diagram of a transmission system of a device-to-device communication synchronization signal in the embodiment;

fig. 9 is a schematic diagram of a corresponding relationship between frequency-domain positions of a group of synchronization resources in a subframe and time-domain positions of PD2DSS and SD2DSS when the system in example 1 pre-configures 1 group of synchronization resources;

fig. 10 is a schematic diagram of a corresponding relationship between a frequency domain position of 2 groups of synchronization resources in a subframe and time domain positions of PD2DSS and SD2DSS when the system in example 2 is applied to pre-configure 2 groups of synchronization resources;

fig. 11 is a schematic diagram of a corresponding relationship between a frequency domain position of another 2 groups of synchronization resources in a subframe and time domain positions of PD2DSS and SD2DSS when the system in application example 3 pre-configures 2 groups of synchronization resources;

fig. 12 is a schematic diagram of a corresponding relationship between a frequency domain position of 3 groups of synchronization resources in a subframe and time domain positions of PD2DSS and SD2DSS when the system in application example 4 pre-configures 3 groups of synchronization resources;

fig. 13 is a schematic diagram of a corresponding relationship between a frequency domain position of another 3 groups of synchronization resources in a subframe and time domain positions of PD2DSS and SD2DSS when the system in application example 5 pre-configures 3 groups of synchronization resources;

fig. 14 is a schematic diagram of the correspondence relationship between the frequency domain position of the group of synchronization resources in the subframe and the root sequences of PD2DSS and SD2DSS when the system in application example 6 pre-configures 1 group of synchronization resources;

fig. 15 is a structural diagram of a D2D subframe when contention-based D2D communication in application example 7 is used;

fig. 16 is a diagram illustrating that one synchronization resource is reserved per broadcast traffic channel in application example 7.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.

Example (b):

the embodiment provides a method for transmitting a device-to-device communication synchronization signal, which is applied to a D2D sending end, and includes:

a D2D sending end sends D2D synchronization signal D2DSS on a time frequency resource pre-configured on a network side; the preconfigured time-frequency resource refers to n groups of synchronization resources reserved on a D2D transmission bandwidth and used for carrying synchronization signals, and determines a frequency domain position of each group of synchronization resources in a subframe by using a D2DSS located on each group of synchronization resources, where n is a positive integer.

Wherein, prior to transmitting the D2DSS, the method further comprises:

Wherein the D2DSS comprises: a Primary Synchronization Signal (PD 2 DSS) of D2D and/or a Secondary Synchronization Signal (SD 2 DSS) of D2D (Primary D2D Synchronization Signal);

wherein, the composition of the n groups of synchronization resources for carrying synchronization signals includes:

in the frequency domain, respectively consisting of

RB consists of i ═ 1, 2.., n;

in the time domain, the PD2DSS occupies p SC-FDMA symbols, the SD2DSS occupies q SC-FDMA symbols, p and q are positive integers which are more than or equal to 1,the number of RBs occupied by the ith synchronization resource is a positive integer less than or equal to 6. Wherein the content of the first and second substances,

the values of p and q are fixedly configured in advance by the network side.

Wherein both PD2DSS and SD2DSS are transmitted in a sequence form,the total length (the total number of occupied REs) of the sequences of PD2DSS and SD2DSS plus the guard interval on each group of synchronous resources is equal toi＝1,2,...,n。

As a preferred mode, the frequency domain positions of the n groups of synchronization resources for carrying synchronization signals in the subframe include:

With bilateral symmetry as centre

A resource unit RE, wherein i 1,2, n,

for the total number of sub-carriers included in each RB,

or, as another preferred mode, the frequency domain positions of the n groups of synchronization resources for carrying synchronization signals in the subframe include:

when n is 1, there are only 1 set of synchronization resources, whose frequency domain position in the subframe is on one of the following: at the centre of the D2D transmission bandwidthStarting from the upper band edge of the D2D transmission bandwidth on a RB

Lower band edge of the bandwidth on one RB and with D2D transmissionIn the starting position

RB, wherein i ═ 1; preferably, the D2D transmission bandwidth center can be

On each RB;

Starting from the upper band edge of the D2D transmission bandwidth on a RB

RB, wherein i ═ 1, 2; preferably, the two band edges of the upper/lower bandwidth of the D2D transmission bandwidth are used as starting positions

On each RB;

when n is 3, there are 3 sets of synchronization resources whose frequency domain positions in the subframe are respectively at the center of the D2D transmission bandwidth and start at the upper/lower two band edges of the D2D transmission bandwidth

And RB, wherein i is 1,2 and 3.

As a preferred embodiment, when p ═ q ═ 1 is preferred, as shown in fig. 3, the time domain positions of the PD2DSS and the SD2DSS in a subframe specifically include:

1) as shown in fig. 3a, a PD2DSS is on the last SC-FDMA symbol of the first half slot of a subframe, an SD2DSS is located on the SC-FDMA symbol after the PD2DSS, and the interval between the two is any number of SC-FDMA symbols from 0 to 5, which provides the possibility of 6 time domain positions; alternatively, the first and second electrodes may be,

2) as shown in fig. 3b, a PD2DSS is on the last SC-FDMA symbol of the first half slot of a subframe, an SD2DSS is located on the SC-FDMA symbol before the PD2DSS, and the interval between them is any number of SC-FDMA symbols from 1 to 4, providing the possibility of 4 time domain positions; alternatively, the first and second electrodes may be,

3) as shown in fig. 3c, SD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, PD2DSS is on the SC-FDMA symbol before the SD2DSS, and the interval between them is any number of SC-FDMA symbols from 0 to 4, providing 5 time domain positions possible; alternatively, the first and second electrodes may be,

4) as shown in fig. 3d, SD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, PD2DSS is on the SC-FDMA symbol after the SD2DSS, and the interval between them is 0, 1, 3, 4 or 5 SC-FDMA symbols, providing 5 time-domain position possibilities; alternatively, the first and second electrodes may be,

5) as shown in fig. 3e, the symbol positions occupied by PD2DSS and SD2DSS are SC-FDMA symbols uniformly shifted leftward by any number of symbols in 1-4 on the basis of the time domain position of D2DSS in LTE, which provides the possibility of 4 time domain positions; alternatively, the first and second electrodes may be,

6) as shown in fig. 3f, the symbol positions occupied by the PD2DSS and the SD2DSS are SC-FDMA symbols uniformly shifted rightward by any number of symbols in 2-6 on the basis of the time domain position of the D2DSS in LTE, which provides the possibility of 5 time domain positions.

For another example, when p = q =2, as shown in fig. 4a, a time domain position of the PD2DSS and the SD2DSS in a subframe is provided, specifically: PD2DSS and SD2DSS respectively occupy 2 SC-FDMA symbols, PD2DSS is located at 1 st to 2 nd symbols of slot1, and SD2DSS is located at 1 to 2 reciprocal symbols of slot 0;

when p =1 and q =2, as shown in fig. 4b, there is provided a time domain position of the PD2DSS and the SD2DSS in a subframe, specifically: PD2DSS occupies 1 SC-FDMA symbol, SD2DSS occupies 2 SC-FDMA symbols, PD2DSS is located at the last 1 symbol of slot0, and SD2DSS is located at the 1-2 symbols of slot 1.

As a preferred mode, the determining, by using the D2DSS located on each set of synchronization resources, the frequency-domain position of the set of synchronization resources in the subframe includes:

The corresponding relationship between the time domain positions of the PD2DSS and the SD2DSS in the subframe and the frequency domain positions of the synchronization resources in the subframe is preconfigured by the network side, that is, the time-frequency resources preconfigured by the network already include the corresponding relationship between the time domain positions of the PD2DSS and the SD2DSS and the frequency domain positions of the synchronization resources, the network side provides a plurality of corresponding relationships, and different time domain positions indicate different frequency domain positions, that is, as long as the time domain positions can uniquely indicate the frequency domain positions.

Since the relative time-frequency positions of different PD2DSS and SD2DSS represent different pre-configured time-frequency resources, the D2D sending end and the D2D receiving end need to define and select the same pre-configured time-frequency resources on the network side in advance, that is, select the same corresponding relationship between the time-domain position and the frequency-domain position.

As another preferred mode, the PD2DS and the SD2DSS carry root sequences; the determining the frequency domain position of each group of synchronization resources in the subframe by using the D2DSS located on the synchronization resources comprises:

In this way, the corresponding relationship between the time domain positions of the PD2DSS and the SD2DSS and the frequency domain positions of the synchronization resources in the subframe does not need to be considered, so the time domain positions of the PD2DSS and the SD2DSS of the synchronization resources may be fixed, for example, the time domain positions of the PD2DSS and the SD2DSS of the n groups of synchronization resources are the same, for example, the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, and the SD2DSS is on the SC-FDMA symbol after the PD2 DSS.

The corresponding relationship between the root sequence of the PD2DSS and/or the SD2DSS and the frequency domain position of the synchronization resource in the subframe is pre-configured by the network side, that is, the pre-configured time-frequency resource by the network side already contains the corresponding relationship between the root sequence of the PD2DSS and/or the SD2DSS and the frequency domain position of the synchronization resource. However, different root sequences carried by the PD2DSS and the SD2DSS represent different pre-configured time-frequency resources, so the D2D sending end and the D2D receiving end need to agree in advance to select the same pre-configured time-frequency resources on the network side, that is, select the corresponding relationship between the same root sequence and the frequency domain position.

As a preferable mode, as shown in fig. 5, in an out-of-coverage scenario, a specific process of the D2D sending the D2DSS on a time-frequency resource preconfigured by a network side includes:

s101: the D2D sending end monitors the n groups of synchronization resources for carrying synchronization signals;

s102: judging whether idle synchronous resources exist, if so, executing a step S103, otherwise, executing a step S104;

s103: if the idle synchronous resources exist, selecting one idle synchronous resource to send the D2DSS on a time frequency resource pre-configured on a network side;

s104: if no idle synchronous resource exists, waiting for re-monitoring at the next moment, and selecting whether to send a synchronous signal according to a monitoring result.

In addition, in an in-coverage/semi-coverage scenario, as a preferred mode, the D2D sends the D2DSS on a time-frequency resource preconfigured on a network side according to a synchronization resource indicated by a base station.

The time frequency resource pre-configured by the network side is one of the following 2 ways:

1) the time domain positions of PD2DSS and SD2DSS positioned on each group of synchronous resources in the subframe uniquely correspond to the frequency domain positions of the synchronous resources in the subframe, and different time domain positions correspond to different frequency domain positions;

the frequency domain position and the time domain position may specifically adopt one of the above descriptions, as long as the time domain position can uniquely indicate the frequency domain position; and when the PD2DSS and the SD2DSS are transmitted, the signals are transmitted at the frequency domain position and the time domain position.

2) The root sequences of the PD2DSS and SD2DSS located on each set of synchronization resources correspond uniquely to the frequency domain positions of the synchronization resources in the subframe, with different root sequences corresponding to different frequency domain positions.

The method comprises the steps of sending PD2DSS and SD2DSS, wherein the PD2DSS and the SD2DSS carry root sequences, and sending the PD2DSS and the SD2DSS at frequency domain positions corresponding to the root sequences. The time domain position can be any position in the subframe and is configured in advance by the network side.

The embodiment also provides a method for transmitting device-to-device communication synchronization signals, which is applied to a D2D receiving end, and includes:

a D2D receiving end receives a D2D synchronization signal D2DSS on a time frequency resource pre-configured on a network side; the preconfigured time-frequency resource refers to n groups of synchronization resources reserved on a D2D transmission bandwidth and used for carrying synchronization signals, and determines a frequency domain position of each group of synchronization resources in a subframe by using a D2DSS located on each group of synchronization resources, where n is a positive integer.

Wherein, prior to receiving the D2DSS, the method further comprises:

Wherein the D2DSS comprises: PD2DSS and SD2 DSS;

in the frequency domain, respectively consisting of

RB consists of i ═ 1, 2.., n;

in the time domain, the PD2DSS occupies p SC-FDMA symbols, the SD2DSS occupies q SC-FDMA symbols, p and q are positive integers which are more than or equal to 1,indicates the number of RBs occupied by the ith synchronization resource asA positive integer of 6 or less.

Wherein the content of the first and second substances,the values of p and q are fixedly configured in advance by the network side.

Or, in another preferred mode, receiving PD2DS and SD2DSS carrying root sequences;

However, different root sequences carried by the PD2DSS and the SD2DSS represent different pre-configured time-frequency resources, so the D2D sending end and the D2D receiving end need to agree in advance to select the same pre-configured time-frequency resources on the network side, that is, select the corresponding relationship between the same root sequence and the frequency domain position.

As a preferred mode, the D2D receiving end already defines a corresponding relationship between time-domain positions of the PD2DSS and the SD2DSS in the subframe and frequency-domain positions of the synchronization resources in the subframe with the transmitting end, that is, selects the time-frequency resources preconfigured by the network side that are the same as the transmitting end, as shown in fig. 6, a specific process of the D2D receiving the D2DSS on the time-frequency resources preconfigured by the network side includes:

s201: the D2D receiving end scans the full frequency band within the range of the D2D transmission frequency band, obtains PD2DSS on n groups of synchronous resources, and obtains time slot synchronization according to the received PD2 DSS;

s202: for each group of synchronous resources, searching the SD2DSS forwards or backwards on the basis of the time domain position of the PD2DSS, and determining the corresponding frequency domain position of the synchronous resources in the subframe according to the time domain positions of the PD2DSS and the SD2DSS in the subframe;

s203: and the D2D receiving terminal realizes time synchronization and frequency synchronization with the D2D transmitting terminal according to the received PD2DSS and SD2DSS, and/or acquires the ID information of the D2D transmitting terminal.

As a preferred mode, the D2D receiving end already defines a corresponding relationship between the root sequence of the PD2DSS and/or the SD2DSS and the frequency domain position of the synchronization resource in the subframe with the transmitting end, that is, selects the time-frequency resource preconfigured on the network side that is the same as the transmitting end, as shown in fig. 7, a specific process of the D2D receiving end receiving the D2DSS on the time-frequency resource preconfigured on the network side includes:

s301: the D2D receiving end scans the full frequency band within the range of the D2D transmission frequency band, obtains PD2DSS on n groups of synchronous resources, and obtains time slot synchronization according to the received PD2DSS, wherein the PD2DSS carries a root sequence;

s302: for each group of synchronous resources, receiving SD2DSS carrying root sequences, and determining corresponding frequency domain positions of the synchronous resources in a subframe according to the root sequences carried by the PD2DSS and/or the root sequences carried by the SD2 DSS;

s303: and the D2D receiving terminal realizes time synchronization and frequency synchronization with the D2D transmitting terminal according to the received PD2DSS and SD2DSS, and/or acquires the ID information of the D2D transmitting terminal.

As shown in fig. 8, this embodiment further provides a transmission system of a device-to-device communication synchronization signal, including: a transmitting end of a D2D communication and a receiving end of a D2D communication, wherein:

a transmitting end, comprising:

the configuration module is used for acquiring time-frequency resources preconfigured by the network side through interaction with the network side, wherein the preconfigured time-frequency resources refer to n groups of synchronization resources reserved on a D2D transmission bandwidth and used for carrying synchronization signals, and the frequency domain positions of the groups of synchronization resources in a subframe are determined by using D2DSS located on each group of synchronization resources, wherein n is a positive integer;

a sending module, configured to send a D2D synchronization signal D2DSS on a time-frequency resource preconfigured by the network side.

The configuration module determines the time domain position and the frequency domain position of each group of synchronous resources, namely the time frequency resources preconfigured by the network side, and the transmitting module transmits the D2DSS on the time frequency resources.

Wherein the D2DSS comprises: the D2D primary synchronization signal PD2DSS and/or the D2D secondary synchronization signal SD2 DSS;

in the frequency domain, respectively consisting of

Each data block RB consists of i ═ 1, 2.., n;

As another preferred mode, the determining, by using the D2DSS located on each set of synchronization resources, the frequency-domain position of the set of synchronization resources in the subframe includes:

With bilateral symmetry as centre

A resource unit RE, wherein i 1,2, n,

as the total number of subcarriers contained in each RB.

when n is 1, there are only 1 set of synchronization resources whose frequency domain position in the subframe is on one of: at D2D transmission bandwidth centerIs/are as follows

Starting from the upper band edge of the D2D transmission bandwidth on a RB

RB, wherein i ═ 1;

Starting from the upper band edge of the D2D transmission bandwidth on a RB

RB, wherein i ═ 1, 2;

And RB, wherein i is 1,2 and 3.

Wherein, when p ═ q ═ 1 is preferred, the PD2DSS and the SD2DSS are time domain positions in a subframe as shown in fig. 3a to 3 b.

In addition, the configuration module is further configured to negotiate with a D2D receiving end to agree to transmit and receive the D2DSS on a time-frequency resource preconfigured on the same network side before transmitting the D2 DSS.

In addition, the transmitting end further includes:

A receiving end, comprising:

a receiving module, configured to receive a D2D synchronization signal D2DSS on a time-frequency resource preconfigured by the network side.

The D2DSS includes: a D2D primary synchronization signal PD2DSS and a D2D secondary synchronization signal SD2 DSS;

in the frequency domain, respectively consisting of

RB consists of i ═ 1, 2.., n;

In addition, the configuration module is further configured to negotiate with the D2D sender to agree to receive and send the D2DSS on a time-frequency resource preconfigured on the same network side before receiving the D2 DSS.

As a preferred mode, the receiving module is configured to receive a D2DSS on a time-frequency resource preconfigured by the network side, and includes:

As another preferred mode, the receiving module is configured to receive a D2DSS on a time-frequency resource preconfigured by the network side, and includes:

In the following application example, taking the time domain positions of the PD2DSS and the SD2DSS in the sub-frame when p ═ q ═ 1 as an example, the synchronization resources are respectively used in the frequency domain

With bilateral symmetry as centre

On resource elements RE, or with synchronous resources centered in D2D transmission bandwidth

Starting from the upper band edge of the D2D transmission bandwidth on a RB

For example, on each RB, the frequency domain position of each group of synchronization resources in the subframe has a one-to-one correspondence relationship with the time domain positions of the PD2DSS and the SD2DSS, and the time domain positions of the PD2DSS and the SD2DSS indicate the positions of the synchronization resources in the frequency domain, which will be described in detail in this embodiment.

Application example 1

If there are only 1 group of synchronization resources, as shown in fig. 9, the corresponding relationship between the frequency domain position of the group of synchronization resources in the subframe and the time domain positions of PD2DSS and SD2DSS is shown:

when the set of synchronization resources is located in the middle of the D2D transmission band

On each RB as shown in FIG. 9 (a). At this time, PD2DSS and SD2DSS occupy 1 SC-FDMA symbol each, PD2DSS is located at the 3 rd symbol of slot1, and SD2DSS is located at the last symbol of slot 0.

When the set of synchronization resources is located in the middle of the non-D2D transmission band, for example, located at the upper edge of the D2D transmission band as the starting position

On each RB, as shown in FIG. 9(b), PD2DSS is located on the 2 nd last SC-FDMA symbol of slot0, and SD2DSS is located on the 1 SC-FDMA symbol before PD2 DSS.

The receiving end of D2D can determine the frequency domain position of the synchronization signal according to the relative position between PD2DSS and SD2DSS in the time domain,

the network side is fixedly configured in advance.

Application example 2:

in the case that 2 groups of synchronization resources preconfigured on the network side are located at the upper/lower band edges of the D2D transmission bandwidth, as shown in fig. 10, the correspondence between the frequency domain position of the 2 groups of synchronization resources and the time domain positions of the PD2DSS and the SD2DSS is given:

the frequency domain position of the 1 st group of synchronization resources is as follows: starting from the upper band edge of the D2D transmission bandwidth

On each RB, at this time, the PD2DSS and SD2DSS each occupy 1 SC-FDMA symbol, and the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, and the SD2DSS is located on the 1 SC-FDMA symbol immediately after the PD2 DSS;

the frequency domain position of the 2 nd group synchronization resource is as follows: starting from the lower band edge of the D2D transmission bandwidth

On each RB, as shown in fig. 10, at this time, the PD2DSS and SD2DSS occupy 1 SC-FDMA symbol each, and the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, and the SD2DSS is located on the SC-FDMA symbol before the PD2DSS with a spacing of 1 SC-FDMA symbol therebetween.

Note that the time domain positions of the PD2DSS and the SD2DSS are not limited to the two time domain positions given in this application example, and when p ═ q ═ 1, any two time frequency positions listed in time domain positions 1) to 6) of the subframe of the PD2DSS and the SD2DSS may be selected, as long as the time domain positions of the PD2DSS and the SD2DSS may uniquely indicate the frequency domain positions where the synchronization resources are located.

The specific process of transmitting the synchronization signal by the D2D sending end is as follows:

in the out-of-coverage scenario, the D2D sender listens to the 2 groups of synchronization resources, and if the 1 st group is found to be idle, the D2D sender starts at the upper band edge of the D2D transmission bandwidth

Sending PD2DSS and SD2DSS on one RB, wherein the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, and the SD2DSS is located on the 1 SC-FDMA symbol immediately after the PD2 DSS; if the D2D initiator finds group 2 free, then the D2D initiator starts at the lower band edge of the D2D transmission bandwidth

And sending PD2DSS and SD2DSS on one RB, wherein the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is positioned on the SC-FDMA symbol before the PD2DSS, and the interval between the two is 1 SC-FDMA symbol.

If the coverage is in/half coverage, whether the D2D sender sends the synchronization signal on the 1 st group or the 2 nd group synchronization resource is uniformly scheduled by the base station.

The specific process of receiving the synchronization signal by the D2D receiving end is as follows:

firstly, scanning the full frequency band in the range of the D2D transmission frequency band to obtain the PD2DSS on the 2 groups of synchronous resources, and the receiving end of D2D can obtain time slot synchronization according to the received PD2 DSS;

then, the receiving end of D2D searches SD2DSS forwards or backwards based on PD2DSS, if the receiving end of D2D searches SD2DSS backwards based on PD2DSS, then the time domain position of PD2DSS and SD2DSS can determine the synchronous signalStarting at the upper band edge of the D2D transmission bandwidth

On each RB; if the receiving end searches the SD2DSS forward on the basis of the PD2DSS, and the interval between the two is 1 SC-FDMA symbol, then according to the time domain positions of the PD2DSS and the SD2DSS, it can be determined that the synchronization signal is located at the starting position of the lower frequency band edge of the D2D transmission bandwidth

And on one RB.

And finally, the receiving end of the D2D completes time synchronization and frequency synchronization with the transmitting end of the D2D according to the received PD2DSS and SD2DSS, and/or acquires the ID information of the transmitting end of the D2D.

Application example 3:

the situation that 2 groups of synchronization resources preconfigured on the network side are allocated at equal intervals on the whole D2D transmission bandwidth is shown in fig. 11, which gives the correspondence between the frequency domain position of 2 groups of synchronization resources and the time domain positions of PD2DSS and SD2 DSS:

the 2 groups of synchronous resources are respectively arranged on the frequency domain

With bilateral symmetry as centre

And RE, wherein i is 1, 2. Suppose that the total transmission bandwidth of D2D is 50 RBs, i.e.

For the total number of subcarriers, i.e. 12,

total 600 REs, then:

frequency domain institute of group 1 (i = 1) synchronization resourceThe positions are as follows: bilaterally symmetrical with 200RE as center

On each RE, the sub-carrier where 200 REs are located is used as a direct current carrier (DC carrier) and does not carry any data thereon, as shown in fig. 11, at this time, 1 SC-FDMA symbol is occupied by PD2DSS and SD2DSS, and the SD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, and the PD2DSS is located on the 1 SC-FDMA symbol immediately before the SD2 DSS.

The frequency domain of the 2 nd group (i = 2) of synchronization resources is located at: bilaterally symmetrical with 400RE as centerAnd (2) the sub-carrier where 400RE is located is used as a direct current carrier (DC carrier) and does not carry any data thereon, as shown in fig. 11, at this time, 1 SC-FDMA symbol is occupied by PD2DSS and SD2DSS, respectively, and the SD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, and the PD2DSS is located on the 1 SC-FDMA symbol immediately after the SD2 DSS.

Note that the time domain positions of the PD2DSS and the SD2DSS are not limited to the two time domain positions given in this application example, and when p ═ q ═ 1, any two time frequency positions listed in time domain positions 1) to 6) of the subframe of the PD2DSS and the SD2DSS may be selected, as long as the time domain position of the PD2DSS and the SD2DSS may uniquely refer to the frequency domain position of the synchronization resource.

in the out-of-coverage scenario, the D2D sender listens to the 2 sets of synchronization resources, and if the 1 st set is found to be idle, the D2D sender is symmetric on two sides around 200 REs

Sending PD2DSS and SD2DSS on the REs, wherein the SD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, and the PD2DSS is located on the 1 SC-FDMA symbol immediately before the SD2 DSS; if the D2D initiator finds that group 2 is idle, then the D2D initiator is in the process400RE centered bilaterally symmetrical

The PD2DSS and SD2DSS are transmitted on the REs, with SD2DSS on the last SC-FDMA symbol of the first half slot of the subframe and PD2DSS on the 1 SC-FDMA symbol immediately after SD2 DSS.

then, the receiving end of D2D searches SD2DSS forwards or backwards based on PD2DSS, and if the receiving end of D2D searches SD2DSS backwards based on PD2DSS, it can determine that the synchronization signal is located at two sides of 200RE as center, which are symmetric according to the time domain position of PD2DSS and SD2DSSOn RE; if the receiving end searches SD2DSS forward on the basis of PD2DSS, then according to the time domain positions of PD2DSS and SD2DSS, the synchronous signal can be determined to be positioned on two sides symmetrical with 400RE as the center

On RE;

Application example 4:

in the case that 3 groups of synchronization resources preconfigured on the network side are respectively located in the center of the D2D transmission bandwidth and in the upper/lower frequency bands, as shown in fig. 12, the correspondence between the frequency domain position of the 3 groups of synchronization resources and the time domain position of the PD2DSS and the SD2DSS is given:

On each RB, at the moment, each of PD2DSS and SD2DSS occupies 1 SC-FDMA symbol, the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is located on the SC-FDMA symbol after the PD2DSS, and the interval between the two is 1 SC-FDMA symbol;

the frequency domain position of the 2 nd group synchronization resource is as follows: intermediate of D2D transmission bands

On each RB, as shown in fig. 12, at this time, the PD2DSS and SD2DSS each occupy 1 SC-FDMA symbol, and the time domain position thereof extends to the existing scheme of FDD LTE or TDD LTE;

the frequency domain position of the 3 rd group of synchronization resources is as follows: starting from the lower band edge of the D2D transmission bandwidth

On each RB, at this time, the PD2DSS and SD2DSS each occupy 1 SC-FDMA symbol, and the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is located on the SC-FDMA symbol after the PD2DSS, and the interval between them is 2 SC-FDMA symbols.

in the out-of-coverage scenario, the D2D sender listens to the 3 groups of synchronization resources, and if the 1 st group is found to be idle, the D2D sender starts at the upper band edge of the D2D transmission bandwidth

Sending PD2DSS and SD2DSS on each RB, wherein the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is on the SC-FDMA symbol behind the PD2DSS, and the interval between the two is 1 SC-FDMA symbol; if the D2D sender finds group 2 free, then the D2D sender is D2D mid-band

PD2DSS and SD2DSS are sent on each RB, and the time domain positions of the PD2DSS and the SD2DSS are extended to the existing scheme of FDD LTE or TDD LTE; if the D2D initiator finds group 3 free, then the D2D initiator starts at the lower band edge of the D2D transmission bandwidth

The PD2DSS and the SD2DSS are sent on one RB, the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is located on the SC-FDMA symbol behind the PD2DSS, and the interval between the two is 2 SC-FDMA symbols.

If the coverage is in/half coverage, the D2D sender sends the synchronization signal on the synchronization resource of group 1, group 2 or group 3, and the synchronization signal is obtained by scheduling by the base station.

The specific steps of receiving the synchronization signal by the D2D receiving end are as follows:

firstly, scanning the full frequency band in the range of the D2D transmission frequency band to obtain the PD2DSS on the 3 groups of synchronous resources, and the D2D receiving end can obtain time slot synchronization according to the received PD2 DSS;

then, the receiving end of the D2D searches the SD2DSS forwards or backwards based on the PD2DSS, and if the receiving end of the D2D searches the SD2DSS forwards based on the PD2DSS, it can determine the time domain position of the synchronization signal located in the middle of the transmission band of the D2D according to the time domain positions of the PD2DSS and the SD2DSS

On each RB; if the receiving end of D2D searches the SD2D backwards on the basis of PD2DSSSS with an interval of 1 SC-FDMA symbol, the synchronization signal can be determined to be located at the upper band edge of the D2D transmission bandwidth as the starting position according to the time domain positions of the PD2DSS and the SD2DSS

On each RB; if the receiving end of D2D searches back for SD2DSS based on PD2DSS, and the interval between the two is 2 SC-FDMA symbols, then it can be determined that the synchronization signal is located at the beginning position of the lower band edge of the D2D transmission bandwidth according to the time domain positions of PD2DSS and SD2DSS

And on one RB.

Application example 5:

the situation that 3 groups of synchronization resources preconfigured on the network side are allocated at equal intervals on the whole D2D transmission bandwidth is shown in fig. 13, which gives the correspondence between the frequency domain position of the 3 groups of synchronization resources and the time domain positions of PD2DSS and SD2 DSS:

the 3 groups of synchronous resources are respectively arranged on the frequency domain

With bilateral symmetry as centre

RE, where i is 1,2, 3. Assume that the total transmission bandwidth of D2D is 100 RBs, i.e.

For the total number of subcarriers, i.e. 12,a total of 1200 REs, then:

the frequency domain position of the 1 st group of synchronization resources is as follows: bilaterally symmetrical with 300RE as center

On each RE, the sub-carrier where 300 REs are located is used as a direct current carrier (DC carrier) and does not carry any data thereon, as shown in fig. 13, at this time, PD2DSS and SD2DSS each occupy 1 SC-FDMA symbol, and PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, SD2DSS is located on the SC-FDMA symbol before PD2DSS, and the interval between the two is 3 SC-FDMA symbols.

The frequency domain position of the 2 nd group synchronization resource is as follows: bilaterally symmetrical with 600RE as center

On each RE, the subcarrier where 600 REs are located is used as a direct current carrier (DC carrier) and does not carry any data thereon, as shown in fig. 13, at this time, a PD2DSS and a SD2DSS each occupy 1 SC-FDMA symbol, and the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, and the SD2DSS is located on 1 SC-FDMA symbol immediately after the PD2 DSS;

the frequency domain position of the 3 rd group of synchronization resources is as follows: bilaterally symmetrical with 900RE as center

On each RE, the subcarrier where 900 REs are located is used as a direct current carrier (DC carrier) and does not carry any data thereon, as shown in fig. 13, at this time, the PD2DSS and the SD2DSS each occupy 1 SC-FDMA symbol, and the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is located on the SC-FDMA symbol after the PD2DSS, and the interval between the two is 3 SC-FDMA symbols.

in the out-of-coverage scenario, the D2D sender listens to the 3 sets of synchronization resources, and if the 1 st set is found to be idle, the D2D sender is symmetric on two sides around 300 REsSending PD2DSS and SD2DSS on the REs, wherein the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is on the SC-FDMA symbol before the PD2DSS, and the interval between the two is 3 SC-FDMA symbols; if the D2D initiator finds that group 2 is idle, the D2D initiator is symmetric on both sides around 600RE

Sending PD2DSS and SD2DSS on the REs, wherein the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, and the SD2DSS is located on the 1 SC-FDMA symbol immediately after the PD2 DSS; if the D2D initiator finds that group 3 is free, the D2D initiator is symmetric on both sides around 900REAnd transmitting PD2DSS and SD2DSS on the REs, wherein the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is positioned on the SC-FDMA symbol behind the PD2DSS, and the interval between the two is 3 SC-FDMA symbols.

then, the receiving end of D2D searches SD2DSS forwards or backwards based on PD2DSS, if the receiving end of D2D searches SD2DSS backwards by 1 SC-FDMA symbol based on PD2DSS, then according to the time domain position of PD2DSS and SD2DSS, it can be determined that the synchronization signal is located at the bilaterally symmetrical time domain position taking 600RE as the center

On RE; if the receiving end searches SD2DSS forward on the basis of PD2DSS, and the interval between the two is 3 SC-FDMA symbols, then according to the time domain positions of PD2DSS and SD2DSS, it can be determined that the synchronization signal is located at bilateral symmetry centered on 300RE

On RE; if the receiving end searches SD2DSS backwards on the basis of PD2DSS, and the interval between the two is 3 SC-FDMA symbols, then according to the time domain positions of PD2DSS and SD2DSS, it can be determined that the synchronization signal is positioned on two sides of the synchronization signal which is symmetrical and takes 900RE as the center

On each RE.

In the following, taking the time domain positions of the PD2DSS and the SD2DSS in the sub-frame when p ═ q ═ 1 as an example, the synchronization resources are respectively used in the frequency domain

With bilateral symmetry as centre

Starting from the upper band edge of the D2D transmission bandwidth on a RB

One RB and D2D transmissionWith the lower band edge of the input bandwidth as the starting position

For example, on each RB, the frequency domain position of each group of synchronization resources in the subframe has a one-to-one correspondence relationship with the root sequences of the PD2DSS and the SD2DSS, and the root sequences of the PD2DSS and/or the SD2DSS indicate the positions of the synchronization resources in the frequency domain, which will be described in detail in this embodiment.

Application example 6:

the case that 3 groups of synchronization resources preconfigured on the network side are respectively located in the center and the upper/lower frequency band of the D2D transmission bandwidth is shown in fig. 14, which gives the frequency domain positions of the 3 groups of synchronization resources:

PD2DSS carries 3 different root sequences, labeled with 0, 1, 2. The frequency domain position corresponding to the 0 th root sequence is that the D2DSS is positioned in the center of the D2D transmission frequency band; the frequency domain position corresponding to the 1 st root sequence is that the D2DSS is positioned at the upper edge of the D2D transmission frequency band; the frequency domain position corresponding to the 2 nd type root sequence is that the D2DSS is positioned at the lower edge of a D2D transmission frequency band; the time domain positions of the PD2DSS and the SD2DSS are arbitrary and are configured by the network side in a semi-static mode.

Alternatively, for example, SD2DSS carries 168 different root sequences, labeled with 0-167. When the imod3 is 0, and i is 0-167, the corresponding frequency domain position is that the D2DSS is positioned at the center of the D2D transmission frequency band; when the imod3 is 1 and i is 0-167, the corresponding frequency domain position is that the D2DSS is positioned at the upper edge of the D2D transmission frequency band; when the imod3 is 2, and i is 0-167, the corresponding frequency domain position is that the D2DSS is positioned at the lower edge of the D2D transmission frequency band; the time domain positions of the PD2DSS and the SD2DSS are arbitrary and are configured by the network side in a semi-static mode.

As shown in fig. 14, 3 frequency domain positions are shown corresponding to 3 root sequences or 168 different root sequences obtained by taking a film of 3 (3 sets of synchronization resources), but the root sequences themselves cannot be shown in the figure.

On each RB, the sequence which is sent at the moment is the 1 st root sequence or a sequence which satisfies imod 3-1, i-0-167;

On each RB, the 0 th root sequence or a sequence which satisfies imod 3-0 and i-0-167 is sent;

the frequency domain position of the 3 rd group of synchronization resources is as follows: starting from the lower band edge of the D2D transmission bandwidthOn each RB, the 2 nd root sequence or the sequence which meets imod 3-2 and i-0-167 is sent; .

Application example 7:

and respectively reserving a fixed time-frequency resource for each service channel for the transmission of the synchronous signals.

In the contention based D2D communication, a subframe with D2D control and/or data transmission is referred to as a D2D subframe (D2D subframe), each D2D subframe may be divided into a plurality of traffic channel resources in the frequency domain, each traffic channel is composed of N RBs, where N is a positive integer. Each UE listens to and selects an idle traffic channel to transmit the corresponding D2D control and/or broadcast data. Multiple UEs may simultaneously transmit control and/or broadcast data on one D2D subframe using respective contention-successful traffic channels, and other UEs may be in a listening state on the D2D subframe and receive information on one or more traffic channels in the D2D subframe. The structure of the D2D subframe in the contention based D2D communication is shown in fig. 15.

The frequency domain location of the traffic channel is fixed once the system is configured. If the frequency domain positions of the PD2DSS and the SD2DSS on each traffic channel are in a one-to-one correspondence with the time domain positions of the PD2DSS and the SD2DSS, it is only required to ensure that the time domain positions of the PD2DSS and the SD2DSS on different traffic channels are different from each other, as shown in fig. 16, where the selectable time domain position refers to the time domain positions of the PD2DSS and the SD2DSS in a subframe when p is q is 1.

For example, the PD2DSS and SD2DSS of traffic channel 1 each occupy 1 SC-FDMA symbol, and the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is located on the SC-FDMA symbol before the PD2DSS, and the interval between them is 1 SC-FDMA symbol. The PD2DSS and SD2DSS of the traffic channel 2 each occupy 1 SC-FDMA symbol, and the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is located on the SC-FDMA symbol before the PD2DSS, and the interval between the two is 2 SC-FDMA symbols. The PD2DSS and the SD2DSS of the traffic channel m respectively occupy 1 SC-FDMA symbol, the PD2DSS is on the last SC-FDMA symbol of the first half slot of the subframe, the SD2DSS is positioned on the SC-FDMA symbol after the PD2DSS, and the interval between the two is 2 SC-FDMA symbols.

If new root sequences are introduced for the PD2DSS and the SD2DSS, time-domain positions of the PD2DSS and the SD2DSS on each traffic channel may be fixed, that is, the PD2DSS and the SD2DSS may be fixed at the same time-domain position, for example, when p q is 1, one time-domain position may be selected from the time-domain positions of the PD2DSS and the SD2DSS in the subframe, and of course, the time-domain positions of the PD2DSS and the SD2DSS on each traffic channel may be different, as long as it is ensured that the frequency-domain positions where the PD2DSS and the SD2DSS are located and only one root sequence maintain a one-to-one binding relationship.

As can be seen from the foregoing embodiments, compared with the prior art, the transmission method and system, the transmitting end, and the receiving end of the D2D communication synchronization signal provided in the foregoing embodiments mainly solve the problem of synchronization between devices in an out-of-coverage scene.

It will be understood by those skilled in the art that all or part of the steps of the above methods may be implemented by instructing the relevant hardware through a program, and the program may be stored in a computer readable storage medium, such as a read-only memory, a magnetic or optical disk, and the like. Alternatively, all or part of the steps of the above embodiments may be implemented using one or more integrated circuits. Accordingly, each module/unit in the above embodiments may be implemented in the form of hardware, and may also be implemented in the form of a software functional module. The present invention is not limited to any specific form of combination of hardware and software.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Various other embodiments may be devised in accordance with the teachings of the present invention without departing from the spirit and scope thereof, and it should be understood that various changes and modifications may be effected therein by those skilled in the art without departing from the spirit and scope of the invention.

Claims

1. A method of transmitting a device-to-device synchronization signal, comprising:

the sending end of the device-to-device D2D sends a D2D synchronization signal D2DSS on the time frequency resource pre-configured on the same network side; the preconfigured time frequency resources refer to n groups of synchronization resources reserved on a D2D transmission bandwidth and used for carrying synchronization signals, and the preconfigured time frequency resources determine frequency domain positions of each group of synchronization resources in a subframe by using a D2DSS located on each group of synchronization resources, where n is a positive integer;

wherein the determining the frequency domain position of each group of synchronization resources in the subframe by using the D2DSS located on the synchronization resources comprises: the time domain positions of PD2DSS and SD2DSS positioned on each group of synchronous resources in the subframe uniquely correspond to the frequency domain positions of the synchronous resources in the subframe, and different time domain positions correspond to different frequency domain positions;

or, the PD2DSS and the SD2DSS carry root sequences, and the determining, by using the D2DSS located on each group of synchronization resources, the frequency domain position of the group of synchronization resources in a subframe includes: the root sequences of the PD2DSS and SD2DSS located on each set of synchronization resources correspond uniquely to the frequency domain positions of the synchronization resources in the subframe, with different root sequences corresponding to different frequency domain positions.

2. The method of claim 1, wherein:

in the frequency domain, respectively consisting ofEach data block RB consists of i ═ 1, 2.., n;

3. The method of claim 1, wherein:

the frequency domain positions of the n groups of synchronization resources for carrying synchronization signals in the subframe comprise:

With bilateral symmetry as centre

A resource unit RE, where i 1,2,

as the total number of subcarriers contained in each RB.

4. The method of claim 1, wherein:

Starting from the upper band edge of the D2D transmission bandwidth on a RB

RB, wherein i ═ 1;

Starting from the upper band edge of the D2D transmission bandwidth on a RB

Starting at the lower band edge of the D2D transmission bandwidth and over one RBRB, wherein i ═ 1, 2;

On each RB, wherein i ═1,2,3。

5. The method of claim 2, wherein:

when p ═ q ═ 1, the time domain positions of the PD2DSS and the SD2DSS in a subframe specifically include:

6. The method of claim 1, wherein:

prior to transmitting the D2DSS, the method further comprises:

7. The method of claim 6, wherein:

the D2D sending end sends D2DSS on a time-frequency resource pre-configured on a network side, including:

8. A method of transmitting a device-to-device synchronization signal, comprising:

the device-to-device D2D receiving end receives the D2D synchronization signal D2DSS on the same time frequency resource pre-configured by the network side; the preconfigured time frequency resources refer to n groups of synchronization resources reserved on a D2D transmission bandwidth and used for carrying synchronization signals, and the preconfigured time frequency resources determine frequency domain positions of each group of synchronization resources in a subframe by using a D2DSS located on each group of synchronization resources, where n is a positive integer;

wherein the D2DSS comprises: a D2D primary synchronization signal PD2DSS and a D2D secondary synchronization signal SD2 DSS;

alternatively, the first and second electrodes may be,

the PD2DS and the SD2DSS carry root sequences; the determining the frequency domain position of each group of synchronization resources in the subframe by using the D2DSS located on the synchronization resources comprises: the root sequences of the PD2DSS and/or SD2DSS located on each set of synchronization resources correspond uniquely to the frequency domain positions of the synchronization resources in the subframe, with different root sequences corresponding to different frequency domain positions.

9. The method of claim 8, wherein:

in the frequency domain, respectively consisting ofRB consists of i ═ 1, 2.., n;

10. The method of claim 8, wherein:

prior to receiving the D2DSS, the method further comprises:

11. The method of claim 10, wherein:

the D2D receiving end receives D2DSS on a time-frequency resource pre-configured by the network side, including:

12. The method of claim 10, wherein:

13. A transmitting end of a device-to-device synchronization signal, comprising:

a configuration module, configured to obtain, through interaction with a network side, the same time-frequency resource preconfigured by the network side, where the preconfigured time-frequency resource refers to n groups of synchronization resources reserved on a device-to-device D2D transmission bandwidth and used for carrying synchronization signals, and the preconfigured time-frequency resource determines a frequency domain position of each group of synchronization resources in a subframe by using a D2D synchronization signal D2DSS located on each group of synchronization resources, where n is a positive integer;

a sending module, configured to send the D2DSS on a time-frequency resource preconfigured on the network side;

or, the PD2DSS and the SD2DSS carry root sequences; the determining the frequency domain position of each group of synchronization resources in the subframe by using the D2DSS located on the synchronization resources comprises: the root sequences of the PD2DSS and SD2DSS located on each set of synchronization resources correspond uniquely to the frequency domain positions of the synchronization resources in the subframe, with different root sequences corresponding to different frequency domain positions.

14. The transmit end of claim 13, wherein:

in the frequency domain, respectively consisting of

Each data block RB consists of i ═ 1, 2.., n;

15. The transmit end of claim 13, wherein:

With bilateral symmetry as centre

A resource element RE, where i 1,2,. n,

as the total number of subcarriers contained in each RB.

16. The transmit end of claim 13, wherein:

Starting from the upper band edge of the D2D transmission bandwidth on a RBStarting at the lower band edge of the D2D transmission bandwidth and over one RBRB, wherein i ═ 1;

Starting from the upper band edge of the D2D transmission bandwidth on a RB

RB, wherein i ═ 1, 2;

And RB, wherein i is 1,2 and 3.

17. The transmit end of claim 14, wherein:

18. The transmit end of claim 13, wherein:

the configuration module is further configured to negotiate with a D2D receiving end to agree to send and receive the D2DSS on a time-frequency resource preconfigured on the same network side before sending the D2 DSS.

19. The transmit end of claim 18, wherein: further comprising:

20. A receiving end of a device-to-device synchronization signal, comprising:

a receiving module, configured to receive the D2DSS on a time-frequency resource preconfigured on the network side;

alternatively, the first and second electrodes may be,

21. The receiving end of claim 20, wherein:

in the time domain, the PD2DSS occupies p SC-FDMA symbols, the SD2DSS occupies q SC-FDMA symbols, p and q are positive integers greater than or equal to 1,the number of RBs occupied by the ith synchronization resource is a positive integer less than or equal to 6.

22. The receiving end of claim 20, wherein:

the configuration module is further configured to negotiate with the D2D sending end to agree to receive and send the D2DSS on a time-frequency resource preconfigured on the same network side before receiving the D2 DSS.

23. The receiving end of claim 22, wherein:

the receiving module is configured to receive a D2DSS on a time-frequency resource preconfigured on the network side, and includes:

24. The receiving end of claim 22, wherein:

25. A device-to-device synchronization signal transmission system, comprising: the transmitting end according to any one of claims 13 to 19 and the receiving end according to any one of claims 20 to 24.