CN104812059B - Device-to-device synchronization method suitable for user equipment and user equipment - Google Patents

Abstract

The present disclosure provides a device-to-device (D2D) synchronization method and User Equipment (UE) suitable for the user equipment. In one of the exemplary embodiments, the D2D synchronization method includes: receiving the detected signal from the receiver; obtaining a first signal having first timing information and a second signal having second timing information from the detected signal; determining to forward the first timing information or the second timing information based on an upper power limit constraint of the first signal and the second signal and a power difference between the first signal and the second signal; and deciding whether to transmit third timing information inherent to the UE based on whether the first signal and the second signal are below a power threshold.

Description

Applicable device-to-device synchronization method for user equipment and user equipment

technical field

The present disclosure relates to a device-to-device synchronization method applicable to user equipment and user equipment.

Background technique

Device to Device (D2D) communication may refer to a communication method for a user equipment (UE) to directly communicate with another UE in a wireless communication system. Conventionally, whenever a UE transmits a message to another UE, in the case of LTE, a base station or evolved Node B (eNB) will relay the message between the two UEs. But for D2D communication, since the user messages of two UEs can be delivered directly from one UE to the other, the interference of the eNB has been minimized.

However, in order to synchronize a D2D device with the network or another peer device, D2D synchronization information may be delivered from the network or from the peer device to every other UE. Therefore, a D2D synchronization signal (D2D synchronization signal, D2DSS) may be transmitted by using a synchronization source (synchronization source, SS) to enhance network synchronization. When the network implements synchronous D2D communication instead of asynchronous D2D communication (where a device will blindly search for another device), all D2D devices may need to align to network timing according to the synchronization signal.

Therefore, at least two types of devices can be used as synchronization sources. Conventionally, an eNB may act as a synchronization source by periodically transmitting system information (in which a primary synchronization signal (PSS) and a secondary synchronization signal (SSS) are set). When having received the PSS/SSS, the D2D UE may align its timing with that of the eNB. Also, another peer-to-peer device can act as a synchronization source as well. Specifically, any D2D UE can act as a synchronization source to transmit a D2DSS that can be received by another D2D UE.

In order to design a D2D synchronization scheme, several issues will need to be considered. First, a D2D device can receive several synchronization signals at the same time. In that case, the D2D device will consider the object to which it will synchronize itself. If the D2D device chooses to follow the wrong device, the timing of the D2D device will be out of alignment. Moreover, when the D2D device receives two or more different reference timings, there may be timing confusion. In that case, the D2D device will not know which reference timing it should follow. Second, after the D2D device selects the reference timing, the D2D device may not necessarily forward the selected reference timing.

In any case, the D2D synchronization method can be designed to ensure the reliability of network timing and minimize potential timing confusion.

Contents of the invention

Accordingly, the present disclosure is directed to a device-to-device (D2D) synchronization method applicable to user equipment and user equipment (UE).

In one of the exemplary embodiments, the present disclosure is directed to a D2D synchronization method comprising: receiving a detected signal from a receiver; obtaining a first signal having first timing information from the detected signal and a second signal with second timing information; decide to forward the first signal based on the power upper limit constraints of the first signal and the second signal and the power difference between the first signal and the second signal timing information or the second timing information; and determining whether to transmit UE-specific third timing information based on whether all detected signals are lower than a power threshold.

In one of the exemplary embodiments, the present disclosure is directed to a user equipment comprising: a transmitter for transmitting wireless signals; a receiver for receiving wireless signals; and a processing circuit coupled to the a transmitter and the receiver and configured to: receive a detected signal from the receiver; obtain a first signal with first timing information and a first signal with second timing information from the detected signal Two signals; forwarding the first timing information or the second timing information based on the power upper limit constraints of the first signal and the second signal and the power difference between the first signal and the second signal and transmitting, by the transmitter, the UE-inherent third timing information in response to all detected signals being below a power threshold.

In order to make the above-mentioned features and advantages of the present disclosure understandable, the following describes in detail the exemplary embodiments accompanied by the drawings. It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to further explain the disclosure as claimed.

It is to be understood, however, that this summary may not contain all aspects and embodiments of the disclosure, and thus is not meant to be limiting in any way. Moreover, the present disclosure will incorporate improvements and modifications apparent to those skilled in the art.

Description of drawings

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate the embodiments of the disclosure and, together with the description, serve to explain principles of the disclosure.

FIG. 1 illustrates an exemplary wireless communication system with D2D capability.

Figure 2 illustrates the potential timing confusion of a synchronized D2D wireless communication system.

FIG. 3A illustrates a proposed device-to-device synchronization method according to one of the exemplary embodiments of the present disclosure.

Figures 3B-3C provide two different examples that further illustrate the concepts disclosed by Figure 3A.

4A-4C illustrate a first exemplary scenario of the proposed device-to-device synchronization method.

5 illustrates a second exemplary scenario of the proposed device-to-device synchronization method.

6 illustrates a third exemplary scenario of the proposed device-to-device synchronization method.

FIG. 7 illustrates a D2D synchronization signal (D2DSS) triggering flowchart according to one of the exemplary embodiments of the present disclosure.

FIG. 8 is a flowchart summarizing the proposed device-to-device synchronization method.

FIG. 9 illustrates an exemplary UE performing the proposed device-to-device synchronization method in terms of a functional block diagram.

【Description of main component labels】

101: eNB

102: Small cell base station

103a~103k: UE

211: eNB

212: second D2D UE synchronization source

213: D2D UE with chaotic timing

214: the first D2D UE synchronization source

311: eNB

312: UE

313: UE

314: UE

322: UE

323: UE

324: UE

331: First broadcast range

332: second broadcast range

401: UE0

402: UE1

411: eNB

412: S0

413: S1

420: imaginary mark

430: Imaginary mark

440: imaginary mark

501:UE0

502: UE1

511: eNB

512: S0

513: S1

601: UE0

611: eNB

612: S0

901: processing circuit

902: Digital/analog (D/A)/analog/digital (A/D) converter

903: Teleporter

904: Receiver

905: Antenna unit

S111: control signaling

S112: Conventional cellular communication

S113: Discovery signal

S114: D2D synchronization signal

S115: D2D communication

S201, S203, S301, S302, S303, S304, S305, S306, S701, S702, S703, S704, S801, S802, S803: steps

d _th : second edge power threshold

RSRP _PSS/SSS : Reference Signal Received Power of Primary Synchronization Signal/Secondary Synchronization Signal

RSRP _D2DSS : Reference Signal Received Power of Device-to-Device Synchronization Signal

D2DSS0, D2DSS1, D2DSSR: Device-to-device synchronization signal for S0, S1, UE0

P _eNB , P _S0 , P _S1 : RSRP power levels of synchronization signals of eNB, S0, and S1

P _edge : first edge power threshold

Detailed ways

Reference will now be made in detail to exemplary embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and descriptions to refer to the same or like parts.

In order to implement a wireless communication system capable of synchronous D2D communication, it will be necessary to maintain synchronization among UEs in the wireless network. Therefore, in order to provide synchronization of D2D UEs through a wireless network, especially to provide synchronization of UEs near or outside the edge of the coverage of the wireless network, the present disclosure proposes a device-to-device (D2D) synchronization method applicable to user equipment and A user equipment (UE), the method involves selecting a synchronization source and forwarding a reference timing provided by the synchronization source. Through the proposed method and device, timing misalignment and timing confusion will be minimized, so the reliability of D2D communication in wireless networks will be enhanced. Moreover, the range of the D2D communication of the wireless network can be extended without worrying about the synchronization loss of UEs near or outside the boundary of the coverage area of the wireless network.

FIG. 1 illustrates an exemplary wireless communication system with D2D capability. An exemplary wireless communication system 100 will comprise at least one evolved Node B (eNB) 101 acting as a base station synchronization source for each cell and a group of UEs 103a to 103k served by the eNB 101 . The UEs 103a to 103k may include the D2D UE 103a transmitting a discovery signal as denoted by S113, and also include a UE acting as a cluster head. A cell may also include at least one small cell base station 102 . The wireless communication system 100 can provide conventional cellular communication as indicated by S112 to any UE, such as UE 103b, through the eNB 101, and the wireless communication system 100 can also allow UEs 103a to 103k to participate in D2D communication as indicated by S115. The wireless network 100 may provide synchronization for D2D communication by transmitting control signaling as denoted by S111 either from the eNB 101 or from the cluster head UE 103i. The small cell 102 may also act as a synchronization source by transmitting a D2D synchronization signal as represented by S114.

When any of the UEs 103a to 103k is moving within the radio range 150 of the eNB 101, the UE will be considered to be within network coverage. Otherwise, when any of the UEs 103a to 103k moves outside the radio range 150 of the eNB 101, the UE will be considered to be out of network coverage. However, when a UE is out of network coverage, another UE may act as a relay for the UE out of network coverage. For example, UE 103b may act as a relay for UE 103c by delivering user data from eNB 101 to UE 103c. For a UE that is out of network coverage, another UE may also serve as a cluster head that forwards network timing information for the UE out of network coverage. For example, UE 103i may act as a cluster head for UE 103j and UE 103k. However, timing confusion may occur if the UE receives synchronization information from multiple synchronization sources at the same time.

FIG. 2 illustrates a timing disorder situation for a synchronous D2D wireless communication system. In FIG. 2 , the D2D UE 213 may simultaneously receive network timing information from the first D2D UE synchronization source 214 in step S201 and from the second D2D UE synchronization source 212 in step S203 . Although the first D2D UE synchronization source 214 may be synchronized with the eNB 211, the second D2D UE synchronization source 212 outside the coverage of the eNB 211 may provide different timing information from the D2D UE synchronization source 214, so D2D UE 213 may occur The timing is messed up. To avoid timing confusion, the UE will need to know what synchronization source it is timing aligned to. Furthermore, in order to extend the range of D2D communication in a wireless network, the UE may also need to know when to act as a timing repeater that receives timing information and forwards it to Other devices outside the boundaries of network coverage.

FIG. 3A illustrates the proposed process of timing selection and timing forwarding according to one of the exemplary embodiments of the present disclosure. In step S301, the UE will perform detection of one or more synchronization sources in order to align its own timing to one of the detected synchronization sources. In detail, after detecting one or more synchronization signals from one or more synchronization sources, the UE can choose what synchronization signal to synchronize its own timing to based on designed metrics. For example, the designed metric could be the detected average power over a period of time such that the UE will align itself timing to the one synchronization signal with the highest average power over a period of time. The aforementioned average power within a time period may refer to, for example, a reference signal received power (RSRP) of the signal. For another example, the designed metric may also be the relative distance between the synchronization source and the UE.

In step S302, the UE will decide whether to activate the timing forwarding function. When the timing forwarding function is activated, the UE will decide whether to forward the timing information of the selected synchronization source to another device. Activation of the timing forwarding function may be based on an upper constraint of the designed metric of the selected synchronization source and a gap in the designed metric between the selected synchronization source and another external synchronization source. When the upper limit constraint is satisfied and the difference of the designed metric exceeds a certain threshold, the timing forwarding function of the UE will be activated. For example, if the designed metric is the detected average power over a period of time, the UE can decide whether the power cap constraint is satisfied, that is, whether the detected average power of the synchronization signal of the selected synchronization source is less than The first edge power threshold, and the UE can also determine whether the difference of the detected average power between the selected synchronization source and another synchronization source exceeds the second edge power threshold. The other synchronization source may be a synchronization source other than the selected synchronization source having the highest detected average power over a period of time. When the power cap constraint is met and the detected power difference exceeds a second marginal power threshold, the UE may act as a timing repeater to forward timing information from the selected synchronization source to another external device. The two edge power thresholds mentioned above are non-zero positive numbers and will likely vary in different scenarios.

In step S303, if the timing forwarding function of the UE is not activated, the UE will only synchronize with the timing of the selected synchronization source. However, if the timing forwarding function of the UE has been activated, the process moves to step S304. In step S304, the UE will further decide that the timing information of the selected synchronization source will actually be forwarded, or the UE will act as an independent synchronization source for other devices. In general, if the UE is not synchronized to any detected synchronization source, eg, all detected signal powers are below a power threshold, then the UE will act as an independent synchronization source for other devices. In step S305, assuming that the UE cannot align its timing to any of the detected synchronization sources, then the UE will act as an independent synchronization source. In step S306, assuming that the UE can align its timing to the selected synchronization source, the UE will forward the selected timing information to other devices. Figures 3B and 3C provide two different examples for further clarifying the concept of Figure 3A.

In FIG. 3B , assuming that eNB 311 broadcasts system information including PSS and SSS to UE 312 at the edge of the transmission range of eNB 311, UE 312 can forward the timing information embedded in PSS and SSS to the eNB 311 An out-of-coverage UE (eg, UE 314) acts as a synchronization source. However, for UE 312 at the edge of eNB 311's transmission range, the PSS and SSS received from eNB 311 will be reliable. If the PSS and SSS are unreliable, the UE (eg, UE 313) will be considered out of eNB 311 coverage. The UE 313 will then act as an independent synchronization source by transmitting the inherent D2DSS to UEs within the coverage of the UE 313 .

FIG. 3C is another example that further clarifies FIG. 3B in more detail. In the example of FIG. 3C, eNB 311 will broadcast a system information signal containing PSS and SSS. Within the first broadcast range 331 of the eNB 311, the RSRP of the system information signal will exceed the first marginal power threshold, that is, the power cap constraint is not satisfied. Any UE within the first broadcast range 331 will not relay the timing information (eg, PSS/SSS) provided by the eNB 311 to other UEs. However, if the UE is outside the first broadcast range 331, then the UE will be considered to be at the boundary of the broadcast range of the eNB 311 and the timing information of the eNB 311 can be relayed to other UEs. Since UE 322 is just outside the first broadcast range 331 , UE 322 will relay the timing information to UE 323 . If a UE is outside the first broadcast range 331 but within the second broadcast range 332, then the UE will be deemed to have received sufficiently reliable timing information such that the UE can relay the timing information to other UEs. The area between the first broadcast range 331 and the second broadcast range 332 may be defined as an area where the RSRP of the system information signal received by the UE is lower than the first marginal power threshold, but the RSRP of the system information signal received by the same UE is high at the third edge power threshold, wherein the first edge power threshold is greater than the third edge power threshold, and both edge power thresholds are non-zero positive numbers. If the UE is outside the second broadcast range 332, then the UE does not have sufficiently reliable timing information such that the UE will not forward timing accuracy information to other UEs. For example, when UE 323 in FIG. 3C is within the second broadcast range 332 and can supply timing information to UE 324 by transmitting D2DSS aligned to the network, the D2DSS received by UE 324 may be lower than the third marginal power Threshold so that UE 324 does not forward timing information to other UEs. Figures 4 to 7 provide further details of the proposed D2D synchronization method by exploring various exemplary scenarios.

4A-4C illustrate a first exemplary scenario of the proposed device-to-device synchronization method. Figure 4A illustrates a signaling diagram of various D2D wireless network elements. In FIG. 4A, eNB 411 will broadcast PSS/SSS with a power level denoted as P _eNB . Besides receiving P _eNB , UE0 401 may also receive D2DSS0, which represents D2DSS from S0412 and has power level P _S0 . S0 412 may represent another synchronization source with different timing information from eNB 411 , and may be another D2D device outside the range of eNB 411 . UE0 401 may also receive D2DSS1, which represents D2DSS with power level _PS1 from S1413. S1413 may also represent another synchronization source with different timing information from eNB411 and S0412, and may be another D2D device outside the scope of eNB411 and S0412. The D2DSS (D2DSSR) generated by UE0 401 will be transmitted to UE1 402 . For the first exemplary scenario, the D2DSSR will be derived based on the timing information PSS/SSS of the network.

Figure 4B illustrates a first exemplary scenario in further detail. For the first exemplary scenario, it is assumed that for UE0, P _eNB >P _S0 >P _S1 , that is, it is assumed that UE0401 is closer to eNB411 than S0412, and S0412 is closer to UE0401 than S1413 (not shown). If the P _eNB perceived by UE0 is greater than the first power threshold indicated as P _th1 , then UE0 401 will select eNB411 as its timing-aligned synchronization source. If the P _eNB perceived by UE0 401 is greater than the first edge power threshold P _edge , then UE0 401 may be considered to be within the radius from eNB 411 to imaginary marker 420 and UE 401 may not forward timing information to other UEs. However, if the UE0 401 perceived P _eNB is less than the first edge power threshold, UE0 401 forwards the timing information to UE1 402 based on the conditions explained in the following sections. If UE0 401 detects the condition (P _eNB –P _S0 )>d _th , then UE0 401 will forward the D2DSSR to UE1 402, and the D2DSSR can be based on the timing information from eNB 411 alone, or the combined timing information from eNB 411 and D2DSS0 from S0 , where d _th indicates the second edge power threshold. d _th is a predetermined power level threshold, and represents a timing forwarding function activation threshold. The number d _th can be adjusted based on the reliability requirements of the network. In other words, if the network has high reliability requirements, then _dth will be larger. Satisfying the condition P _eNB <P _edge and (P _eNB –P _S0 )>d _th means that UE0401 will be located in the ring-shaped area between the imaginary marker 420 and the imaginary marker 430 in FIG. . If (P _eNB −P _S0 )<=d _th , UE0 401 does not forward the timing information from eNB 411 because it may be considered unreliable.

Figure 4C illustrates a cross-sectional view of Figure 4B. In the top graph, the imaginary marker 440 is where P _eNB =P _S0 . As UE0 401 moves closer to eNB 411, P _eNB will be greater than P _S0 . In the middle graph, the distance between eNB 411 and marker 430 is within a radius of P _eNB >(P _S0 +d _th ). This means that when the UE0 401 moves from the imaginary marker 430 to the imaginary marker 440, the power level of the PSS/SSS will decay by d _th . In the bottom graph of FIG. 4C , the distance between the imaginary mark 420 and the imaginary mark 430 is within the circular region satisfying P _edge >P _eNB >(P _S0 +d _th ). This means that if UE0 401 is within the radius of eNB 411 and hypothetical marker 430 but outside the radius of eNB 411 and hypothetical marker 420, then UE0 401 can forward the timing information of eNB 411 to UE1 402 in D2DSSR.

5 illustrates a second exemplary scenario of a device-to-device synchronization method. For the second exemplary scenario, UE0 501 is closer S0 512 than eNB 511 . Therefore, if UE0501 detects that P _eNB >= P _th1 , then UE0501 will select the timing from eNB 511 because, although UE0501 is closer to S0512 than to eNB 511, eNB 511 will be considered as having higher priority level, where P _th1 is the first power threshold. UE0 501 will then synchronize its timing with the PSS/SSS from eNB 511, but UE 501 may not forward the timing information to other UEs. However, if UE0501 detects that P _eNB <P _th1 and P _S0 >=P _th2 , then UE0501 will synchronize with the timing information from S0512 , where P _th2 is indicated as the second power threshold. This means that UE0501 may be too far away from eNB 511 and/or not receive sufficient power from eNB 511, but UE0501 will receive sufficient power from S0512 such that UE0501 will be able to synchronize with S0512.

For the situation when UE0 is located around the edge of the coverage area of S0512, or in other words, when P _S0 detected by UE0501 is smaller than the predetermined first edge power threshold P _edge , then if UE0501 detects that (P _S0 −P _eNB )> d _th , then UE0 will start forwarding the timing information from S0512 to possibly between eNB 511 and S0512 by transmitting a D2DSSR with the timing of D2DSS0 or with the combined timing of D2DSS0 and eNB or with the combined timing of all D2DSSs that UE0501 has received Other UEs near or outside the coverage area. The timing forwarding activation threshold, ie, the second edge power threshold d _th , may be adjusted based on the reliability requirements of the entire D2D communication system.

6 illustrates a third exemplary scenario of a device-to-device synchronization method. For this exemplary scenario, when UE0601 detects that P _eNB , P _S0 and P S1 respectively received from eNB 611, S0612 and _S1 (not shown) are all lower than the predetermined power threshold, that is, P _eNB <P _th1 and ( P _S0 , P _S1 )<P _th2 , then the UE0601 is considered to be outside the coverage of the eNB network and S0612, where P _th1 is the first power threshold and P _th2 is the second power threshold. In this case, UE0 601 will not be synchronized with timing information from any of the aforementioned synchronization sources. Instead, the UE0601 will transmit the D2DSSR to other peer devices or D2D UEs within range of the UE0601 based on its inherent timing information.

FIG. 7 is a flowchart illustrating D2D Synchronization Signal (D2DSS) triggering that may relate to the aforementioned scenarios. It is assumed that the UE has received PSS/SSS from the base station and at least one D2DSS from an external synchronization source. In step S701, it is assumed that the D2D-capable UE has detected PSS/SSS from at least one system information transmitted by the base station, and the D2D-capable UE has also detected the strongest D2DSS from at least one system information transmitted by the synchronization source. In step S702, the UE will determine whether it detects that the RSRP of the PSS/SSS (RSRP _PSS/SSS ) is lower than a predetermined PSS/SSS threshold (threshold _PSS/SSS ), where the threshold _PSS/SSS is defined the same as P _th1 . If the RSRP of the PSS/SSS is above a predetermined PSS/SSS threshold, then the first exemplary scenario mentioned above will apply. If the RSRP of the PSS/SSS is lower than the predetermined PSS/SSS threshold, step S703 will be executed. In step S703, the UE will determine whether the received RSRP of the D2DSS (RSRP _D2DSS ) is lower than a predetermined D2DSS threshold (threshold _D2DSS ), where the threshold _D2DSS is defined the same as P _th2 . If the RSRP of the received D2DSS is above a predetermined D2DSS threshold, then the second exemplary scenario mentioned above will apply. If the received RSRP of the D2DSS is lower than the predetermined D2DSS threshold, then step S704 will be performed and the third exemplary scenario mentioned above will apply. In step S704, the UE will transmit the D2DSS based on the inherent timing information of the UE.

FIG. 8 is a flowchart summarizing the proposed device-to-device synchronization method from the perspective of a D2D-capable UE. In step S801, the UE will receive the detected signal from the receiver, and the UE will obtain a first signal with first timing information and a second signal with second timing information from the detected signal. In step S802, the UE will decide to forward the first timing information or The second timing information. In step S803, the UE will decide whether to transmit UE-specific third timing information based on whether all detected signals are lower than the power threshold.

In one of the exemplary embodiments, the first timing information may include a primary synchronization signal (PSS) and a secondary synchronization signal (SSS), and if the first signal is higher than a first power threshold, the UE may synchronize to the first First timing information of a signal, and if the first signal is lower than the first power threshold, not synchronized to the first timing information of the first signal.

In one of the exemplary embodiments, the UE may synchronize to the second signal if the second signal is above the second power threshold and the first signal is below the first power threshold.

In one of the exemplary embodiments, the UE may transmit the third timing information only if the first signal is below the first power threshold and the second signal is below the second power threshold.

In one of the exemplary embodiments, the UE may forward the first timing information if the first signal is below the first marginal power threshold, and not forward the first timing information if the first signal is above the first marginal power threshold 1. Timing information.

In one of the exemplary embodiments, the UE may forward the second timing information if the second signal is below the first marginal power threshold, and not forward the second timing information if the second signal is above the first marginal power threshold Two timing information.

In one of the exemplary embodiments, the UE may forward the first timing information if the first signal has a higher power than the second signal by a second marginal power threshold, and if the first signal does not have a higher power than the second signal If the power is less than the second edge power threshold, the UE does not forward the first timing information.

In one of the exemplary embodiments, the UE may forward the second timing information if the second signal has a power higher than the first signal by more than a second marginal power threshold, and if the second signal does not have a higher power than the first signal If the power is higher than the second edge power threshold, the UE does not forward the second timing information.

In one of the exemplary embodiments, the above-mentioned first and second edge power thresholds are adjustable.

Figure 9 illustrates an exemplary UE in terms of a functional block diagram. The UE of FIG. 9 will correspond to the UE of FIG. 8 so as to be able to perform the proposed device-to-device synchronization method according to a functional block diagram. The UE contains at least (but not limited to) a processing circuit 901 coupled to a digital/analog (D/A)/analog/digital (A/D) converter 902, a transmitter 903, a receiver 904, and one or more antenna elements 905. The transmitter 903 will transmit the signal wirelessly and the receiver 904 will receive the signal wirelessly. The transmitter 903 and receiver 904 may also perform operations such as low noise amplification, impedance matching, frequency mixing, frequency up-conversion or down-conversion, filtering, amplification, and the like. (D/A)/(A/D) converter 902 is configured to convert from an analog signal format from receiver 904 to a digital signal format that can be digitally processed by processing circuit 901 . On the other hand, the (D/A)/(A/D) converter 902 may receive a signal from the processing circuit 901 and convert the signal in a digital signal format to an analog signal format for transmission to the transmitter 903 . The processing circuit 901 is configured to process digital signals and execute procedures of the proposed D2D synchronization method according to the aforementioned exemplary embodiments of the present disclosure. Also, the processing circuit 901 is optionally coupled to a non-transitory storage medium for storing programming code, device configuration, codebook, buffered or persistent data, and the like. The functions of the processing circuit 901 may be implemented using programmable units such as microprocessors, microcontrollers, DSP chips, FPGAs, and the like. The functions of the processing circuit 901 may also be implemented by a stand-alone electronic device or IC, and the functions performed by the processing circuit may be implemented within a network of hardware or software.

In this disclosure, 3GPP-like keywords or terms are used as examples only to present inventive concepts according to this disclosure; however, the same concepts presented in this disclosure can be applied to any other system by those skilled in the art, such as IEEE802.11 , IEEE 802.16, WiMAX, etc.

In this disclosure, the term "user equipment" (UE) may refer to various embodiments, which may include, for example but not limited to, mobile stations, advanced mobile stations (AMS), servers, clients, Desktop computers, laptop computers, network computers, workstations, personal digital assistants (PDAs), tablet personal computers (personal computers, PCs), scanners, telephone devices, pagers, cameras, televisions, handheld Video game devices, music devices, wireless sensors, and more. In some applications, a UE may be a stationary computer device operating in a mobile environment such as a bus, train, airplane, boat, automobile, and the like.

No element, act, or instruction used in the detailed description of the disclosed embodiments of the present application should be construed as absolutely critical or essential to the disclosure unless explicitly described as such. Also, as used herein, the word "a" and "an" can include more than one item. If only one item is intended, then the term "single" or similar language will be used. Furthermore, as used herein, the term "any of" preceding a listing of items and/or categories of items is intended to include said items and/or categories of items individually or in combination with other items and/or Other item categories are "any of", "any combination of", "any multiple of", and/or "any combination of multiples of". Also, as used herein, the term "collection" is intended to encompass any number of items, including zero. Also, as used herein, the term "quantity" is intended to include any quantity, including zero.

Those skilled in the art will recognize that various modifications and changes can be made in the structure of the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the above, it is intended that the present disclosure cover modifications and variations of this disclosure provided they come within the scope of the appended claims and their equivalents.

Claims (14)

1. a kind of device suitable for user equipment is to device synchronous method, which is characterized in that the method includes：

Detected signal is received from receiver；

The first signal with the first timing information and second with the second timing information is obtained from the detected signal Signal, wherein first timing information includes primary synchronization signals and secondary synchronizing signal, second timing information includes First device is to device synchronizing signal；

If being synchronized to first timing information of first signal, based on first signal and the second signal The upper limit of the power constrains and the difference power between first signal and the second signal determines to forward first timing information, The wherein described upper limit of the power constraint includes first edge power threshold；And

Whether decide whether less than power threshold to transmit the user equipment based on first signal and the second signal Intrinsic third timing information, wherein being only less than second less than the first power threshold and the second signal in first signal In the case of power threshold, the third timing information is just transmitted.

2. according to the method described in claim 1, it is characterized in that, further including：

If first signal is higher than first power threshold, it is synchronized to first sequential letter of first signal Breath；And

If first signal is less than first power threshold, asynchronous first sequential to first signal is believed Breath.

3. according to the method described in claim 2, it is characterized in that, further including：

If the second signal is higher than second power threshold and first signal is less than first power threshold, together Walk the second signal；And

Based on the constraint of the upper limit of the power of first signal and the second signal and first signal and the second signal Between difference power determine to forward second timing information.

4. according to the method described in claim 2, it is characterized in that, further including：

If first signal is less than the first edge power threshold and first signal is with higher than the second signal The excessively power of second edge power threshold then forwards first timing information；And

If first signal does not have higher than the first edge power threshold or first signal than the second signal Exceed in the power of the second edge power threshold, does not then forward first timing information.

5. according to the method described in claim 3, it is characterized in that, further including：

Second signal less than the first edge power threshold and the second signal have than first signal exceed in The power of second edge power threshold then forwards second timing information；And

Do not have than first signal higher than the first edge power threshold or the second signal in the second signal Exceed in the power of the second edge power threshold, does not then forward second timing information.

6. according to the method described in claim 4, it is characterized in that, the wherein described first edge power threshold and second side Both edge power thresholds are adjustable.

7. according to the method described in claim 1, it is characterized in that, the third timing information includes that second device is same to device Walk signal.

8. a kind of user equipment, which is characterized in that including：

Conveyer, for transmitting wireless signal；

Receiver, for receiving wireless signal；And

Processing circuit is couple at least one conveyer and at least one receiver and is configured for use in：

Detected signal is received from the receiver；

The first signal with the first timing information and second with the second timing information is obtained from the detected signal Signal, wherein first timing information includes primary synchronization signals and secondary synchronizing signal, second timing information includes First device is to device synchronizing signal；

If being synchronized to first timing information of first signal, the work(based on first signal and the second signal The rate upper limit constrain and the difference power between first signal and the second signal and forward first timing information, wherein institute It includes first edge power threshold to state upper limit of the power constraint；And

It is intrinsic less than power threshold the user equipment to be transmitted by the conveyer in response to all detected signals Third timing information, wherein being only less than the second power-threshold less than the first power threshold and the second signal in first signal In the case of value, the third timing information is just transmitted.

9. user equipment according to claim 8, which is characterized in that the processing circuit be further configured for：

If first signal is higher than first power threshold, it is synchronized to first sequential letter of first signal Breath；And

If first signal is less than first power threshold, asynchronous first sequential to first signal is believed Breath.

10. user equipment according to claim 9, which is characterized in that the wherein described processing circuit be further configured with For：

If the second signal is higher than the second power threshold and first signal is less than first power threshold, it is synchronized to The second signal；And

Based on the constraint of the upper limit of the power of first signal and the second signal and first signal and the second signal Between difference power determine to forward second timing information.

11. user equipment according to claim 9, which is characterized in that the wherein described processing circuit be further configured with For：

If first signal is less than the first edge power threshold and first signal is with higher than the second signal The excessively power of second edge power threshold then forwards first timing information via the conveyer；And

If first signal does not have higher than the first edge power threshold or first signal than the second signal Exceed in the power of the second edge power threshold, then forwards first timing information not via the conveyer.

12. user equipment according to claim 10, which is characterized in that the wherein described processing circuit be further configured with For：

If the second signal is less than the first edge power threshold and the second signal is with higher than first signal The excessively power of second edge power threshold then forwards second timing information via the conveyer；And

If the second signal does not have higher than the first edge power threshold or the second signal than first signal Exceed in the power of the second edge power threshold, then forwards second timing information not via the conveyer.

13. user equipment according to claim 11, which is characterized in that the wherein described first edge power threshold and described Both second edge power thresholds are adjustable.

14. user equipment according to claim 8, which is characterized in that the third timing information includes second device pair Device synchronizing signal.