DEVICE-TO-DEVICE (D2D) COMMUNICATION

FIELD

[0001] Embodiments of the present disclosure generally relate to communication technologies, and more specifically, to a method, device and computer-readable medium for device-to-device (D2D) communication.

BACKGROUND

[0002] Nowadays, in the 3 ^rd Generation Partnership Project (3GPP) on standardization of Long Term Evolution (LTE), there has been proposed a further enhancement Device-to-Device (feD2D) technology For example, at 3GPP RAN#72 and RAN#73 conferences, there has been raised the research technical subject for the D2D communication of Internet of Things (IoT) and a user wearable mobile device in the Long Term Evolution (LTE). The technology can support sidelink communications of an IoT device with a limited operating bandwidth and a wearable device in a relay environment. In a feD2D scenario, a remote terminal device (for example, a wearable device) is located adjacent to a relay terminal device. Therefore, the power efficiency and the resource utilization of the relay terminal device and the remote terminal device (for example, the user wearable mobile device) are important research subjects as well.

SUMMARY

[0003] Generally, embodiments of the present disclosure relate to a method of D2D communication and corresponding terminal devices.

[0004] In a first aspect, embodiments of the present disclosure provide a method for device-to-device (D2D) communication. The method comprises: at a remote terminal device in the D2D communication, transmitting, to a relay terminal device in the D2D communication, a discovery request to the D2D communication; obtaining an association between a channel condition related to a discovery of the D2D communication and at least one set of resources in a resource pool; and monitoring, based on the association, a response to the discovery request from the relay terminal device over the resource pool.

[0005] In a second aspect, embodiments of the present disclosure provide a method for device-to-device (D2D) communication. The method comprises: at a relay terminal device in the D2D communication, obtaining an association between a channel condition related to a discovery of the D2D communication and at least one set of resources in a resource pool; in response to receiving, from a remote terminal device in the D2D communication, a discovery request to the D2D communication, determining a current channel condition for a discovery of the D2D communication; and determining, based on the association, a set of resources from the at least one set of resources for responding to the discovery request, the set of resources corresponding to the current channel condition.

[0006] In a third aspect, embodiments of the present disclosure provide a remote terminal device. The remote terminal device comprises: at least one processor; and a memory coupled to the at least one processor and storing instructions, the instructions, when executed by the at least one processor, causing the remote terminal device to perform acts comprising: transmitting, to a relay terminal device in the D2D communication, a discovery request to the D2D communication; obtaining an association between a channel condition related to a discovery of the D2D communication and at least one set of resources in a resource pool; and monitoring, based on the association, a response to the discovery request from the relay terminal device over the resource pool.

[0007] In a fourth aspect, embodiments of the present disclosure provide a relay terminal device. The relay terminal device comprises: at least one processor; and a memory coupled to the at least one processor and storing instructions, the instructions, when executed by the at least one processor, causing the relay terminal device to perform acts comprising: obtaining an association between a channel condition related to a discovery of the D2D communication and at least one set of resources in a resource pool; in response to receiving, from a remote terminal device in the D2D communication, a discovery request to the D2D communication, determining a current channel condition for the discovery of the D2D communication; and determining, based on the association, a set of resources from the at least one set of resources for responding to the discovery request, the set of resource corresponding to the current channel condition.

[0008] In a fifth aspect, embodiments of the present disclosure provide a computer readable storage medium. The computer readable storage medium includes program codes stored thereon, and the program codes, when executed by a device, causes the device to perform the method according to the first aspect or second aspect.

[0009] It would be appreciated that this Summary is not intended to identify key features or essential features in the embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will be made apparent through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] The above and other objectives, features, and advantages of example embodiments of the present disclosure will become more apparent, through the following detailed description with reference to the accompanying drawings in which:

[0011] Fig. 1 illustrates a block diagram of an example communication system in which embodiments of the present disclosure can be implemented; [0012] Fig. 2 illustrates an interaction diagram of communication according to some embodiments of the present disclosure;

[0013] Fig. 3 illustrates a flowchart of an example method according to some embodiments of the present disclosure;

[0014] Fig. 4 illustrates a flowchart of an example method according to some embodiments of the present disclosure;

[0015] Fig. 5 illustrates a block diagram of a communication device according to some embodiments of the present disclosure;

[0016] Fig. 6 illustrates a block diagram of a communication apparatus according to some embodiments of the present disclosure; and [0017] Fig. 7 illustrates a block diagram of a communication apparatus according to some embodiments of the present disclosure.

[0018] Throughout the drawings, the same or similar reference symbols refer to the same or similar elements.

DETAILED DESCRIPTION OF EMBODIMENTS

[0019] Embodiments of the present disclosure will now be described in more detail with reference to the drawings. Although some embodiments of the present disclosure are illustrated in the drawings, it would be appreciated that the present disclosure may be implemented in various manners but not be limited to embodiments as described herein. By contrast, these embodiments are provided to understand the present disclosure more thoroughly and completely. It is to be understood that the drawings and embodiments of the present disclosure are provided only as examples and is not intended for limiting the scope disclosed herein in any manner.

[0020] The term "network device" used herein refers to any appropriate entity or device that can provide cells or coverage which enables a terminal device to access a network or receive services. An example of the network device includes a base station, for example. The term "base station" (BS) used herein can represent a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a remote radio unit (RRU), a radio header (RH), a remote radio header (RRH), a relay, a low-power node such as a femto station and a pico station, and the like.

[0021] The term "terminal device" or "user device" (UE) used herein refers to any entity or device capable of communicating with a network device or with another one in wireless. For example, the terminal device can include a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), a mobile station (MS), or an access terminal (AT), the foregoing device on a vehicle, a machine or an electric appliance with a communication function, and the like. [0022] As used herein, the term "include" and its variants are to be read as open-ended terms that mean "includes, but is not limited to." The term "based on" is to be read as "based at least in part on." The term "an embodiment" is to be read as "at least one example embodiment;" and "another embodiment" is to be read as "at least one further embodiment." Other definitions, explicit and implicit, may be included below. [0023] Fig. 1 illustrates an example communication system 100 in which embodiments of the present disclosure can be implemented. In this example, the communication system 100 includes a network device 110, a remote terminal device 120 and a relay terminal device 130. It would be appreciated that the term "remote terminal device" or "remote user equipment" used herein refers to a terminal device that is in a sidelink communication with a relay terminal device and can further communicate with a network device through relay by a relay terminal device. The term "relay terminal device" or "relay user equipment" used herein refers to a relay terminal device that can be in a sidelink communication with a remote terminal device. The relay terminal device can provide the relay service to the remote terminal device via the sidelink communication, such that the remote terminal device can communicate with the network device by means of the relay service.

[0024] The network device 100 can communicate with the relay terminal device 130. The remote terminal device 120 and the relay terminal device 130 can be any appropriate terminal devices, and their respective roles in network communication are determined based on relative locations thereof. That is to say, the remote terminal device 120 is located adjacent to the relay terminal device 130, and thus can be in the D2D communication (for example, the sidelink communication) with the relay terminal device 130, thereby communicating with the network device 110. It would be appreciated that the respective numbers of network devices, relay terminal devices and remote terminal devices are only used for description, without suggesting any limitations. The communication system 100 can include any appropriate number of network devices, relay terminal devices or remote terminal devices.

[0025] The communication in the communication system 100 can employ by any appropriate communication technologies and a corresponding communication standard. An example of the communication technology includes, but is not limited to, Long Term Evolution (LTE), LTE-advanced (LTE-A), wideband code division multiple access (W-CDMA), code division multiple access (CDMA), a global system for mobile communication (GSM), orthogonal frequency division multiplexing (OFDM), wireless local area networks (WLAN), worldwide interoperability for microwave access (WiMAX), Bluetooth, Zigbee technology, machine type communication (MTC), D2D, M2M or the like. Moreover, the communication can be performed according to any appropriate communication protocols which includes, but is not limited to, a transmission control protocol (TCP)/internet protocol (IP), a hypertext transfer protocol (HTTP), a user datagram protocol (UDP), a session description protocol (SDP) and the like.

[0026] The discovery procedure of the legacy D2D communication includes the following two modes: one mode (which is referred to as "Mode A") that requires the relay terminal device to broadcast a notification message, and the other mode (which is referred to as "Mode B") that requires the relay terminal device to send a response message in response to a solicitation message from one remote terminal device. In the Mode A, the relay terminal device uses a plurality of frequency bands in one subframe to broadcast the notification message. Consequently, the remote terminal device is required to monitor the entire operating frequency band of the relay terminal device to discover an appropriate relay terminal device. However, the operating frequency band of the relay terminal device exceeds far beyond a range of operating bandwidth of a remote terminal device with a narrowband. As such, the remote terminal device with a narrowband must monitor the operating frequency band of the relay terminal device segment by segment per its operating frequency band, which requires long time and a great deal of energy, thus resulting in a low efficiency

[0027] In the Mode B, the remote terminal device transmits a discovery request (for example, a solicitation message) of the D2D communication to initiate the D2D communication. The relay terminal device receives the discovery request from the remote terminal device and further transmits a message of responding to the request to the remote terminal device. Since the relay terminal device lacks of information about which resources should be utilized to respond to the message, it is likely that the relay terminal device randomly selects a resource for responding to the message. Therefore, the remote terminal device must monitor all resources to receive the response. This leads to the waste of energy and power of the remote terminal device. In addition, since the relay terminal device randomly selects the resource for responding to the request, there is a case where multiple relay terminal devices select the same resource, causing the remote terminal unable to receive the response correctly. The remote terminal device is also unable to preferentially receive a response from a relay terminal device having a good channel condition for a discovery of the D2D communication.

[0028] There has been proposed a method of associating a resource for transmitting a discovery request of D2D communication with a resource for responding to the request. Specifically, the relay terminal device can determine the resource for responding to the request based on the resource for the remote terminal device to transmit the discovery request of the D2D communication. Therefore, it is unnecessary for the remote terminal device to monitor all the resources to receive the response. However, there still exists the case that multiple relay terminal devices select the same resource, and the remote terminal device is unable to receive the response correctly. Furthermore, the remote terminal device is still unable to preferentially receive a response from a relay terminal device having a good channel condition for the discovery of the D2D communication, and energy waste also occurs in this method.

[0029] In order to better implement the discovery procedure of the D2D communication, embodiments of the present disclosure provide an association between the channel condition for the discovery of the D2D communication and a set of resources for transmission. Fig. 2 illustrates an interaction signaling diagram 200 between D2D communication entities according to embodiments of the present disclosure. The term "resource pool" used herein is a general term for several time domain and/or frequency domain resources used for transmitting information. The term "set of resources" used herein is a set that comprises a certain number of time domain and/or frequency domain resources for transmitting information (which is greater than or equal to 1).

[0030] Generally, according to embodiments of the present disclosure, the remote terminal device 120 may transmit 210 a discovery request for the D2D communication to the relay terminal device 130. Alternatively, a network device 210 may transmit 220, to the remove terminal device 120 and the relay terminal device 130, an association between the channel condition related to the discovery of the D2D communication and at least one set of resources in the resource pool. This association specifies a correspondence between respective channel conditions and respective set of resources. In other words, the association specifies that, for a particular channel condition, a particular set of resources can be used to perform the D2D communication discovery. The channel condition may be represented by a channel-related parameter, such as sidelink discovery reference signal received power (SD-RSRP). For example, the following Table 1 shows a correspondence of the SD-RSRP with different set of resources in the resource pool. The resources in the resource pool may be resources used by a physical sidelink discovery channel (PSDCH), and the set of resources may be a set of PSDCH resources.

Table 1

[0031] In the example as shown in Table 1, the channel condition is represented by the SD-RSRP; different values of SD-RSRP (for example, X ₀ , Xi ... X _n ) may represent different the channel condition; the set of resources may be represented by a set of PSDCH resources, and different sets of PSDCH resources are given different numbers (for example, 1, 2 ... N). Description about Table 1 will be made in more detail below.

[0032] It should be noted that Table 1 is provided only as an example, and the association may be represented in other forms, such as a tree structure and the like. It would be appreciated that the manner of obtaining the association as shown in Fig. 2 is only provided as an example, and the remote terminal device 120 and the relay terminal device 130 may obtain the association in any appropriate manners. For example, the association may be stored in the remote terminal device 120 and the relay terminal device 130 in advance. Alternatively, the association may also be stored in a database accessible by the remote terminal device 120 and the relay terminal device 130.

[0033] The relay terminal device 130 may determine 230a current channel condition for the discovery of the D2D communication in response to receiving a discovery request for the D2D communication from the remote terminal device 120. For example, the relay device 130 may determine the channel condition by measuring the SD-RSRP of the current channel. The relay terminal device 130 can also determine 240, based on the association, a set of resources in at least one set of resources. The set of resources corresponds to the current channel condition and is used for responding to a communication request. The remote terminal device 120 may monitor 250, based on the association, a response to the discovery request from the relay terminal device 130 over the resource pool. [0034] According to the procedure as shown in Fig. 2, the remote terminal device 120 and the relay terminal device 130 are allowed to obtain the association between the channel condition for the discovery of the D2D communication and the set of resources for transmission. The relay terminal device 130 may select a particular resource for responding to the discovery request of the D2D communication based on the association and its current channel condition. The remote terminal device 120 can preferentially receive, based on the association, a response from a relay terminal device which is with a good channel condition for the discovery of the D2D communication. The remote terminal device 120 may save energy and reduce power consumption accordingly. Moreover, embodiments of the present disclosure may prevent relay terminal devices with different channel conditions from selecting the same resource for responding.

[0035] Some example embodiments according to the present disclosure are described now in detail. Fig. 3 illustrates a flowchart of an example method 300 according to some embodiments of the present disclosure. The method 300 may be implemented at the remote terminal device 120 as shown in Fig. 1. [0036] At block 305, the remote terminal device 120 transmits a discovery request for D2D communication to the relay terminal device 130 in the D2D communication. In some embodiments, the discovery request for the D2D communication may be, for example, a solicitation message. In an example embodiment, the resource for transmitting the discovery request may be selected by the remote terminal device 120. Alternatively, the network device 110 may allocate a resource to the remote terminal device 120 to transmit the discovery request. [0037] The remote terminal device 120 may transmit the discovery request for the D2D communication to the relay terminal device 130 in any appropriate manners. For example, in some embodiments, the remote terminal device 120 may broadcast the discovery request. Alternatively, the remote terminal device 120 may multicast the discovery request. The remote terminal device 120 may also unicast the discovery request. It would be appreciated that embodiments of the present disclosure are not limited in this aspect.

[0038] At block 310, the remote terminal device 120 obtains an association between the channel condition related to the discovery of the D2D communication and at least one set of resources in the resource pool. The channel condition related to the discovery of the D2D communication may be any appropriate information, for example, information indicating a channel fading condition. The channel condition related to the discovery of the D2D communication may also be any appropriate information indicating a channel gain.

[0039] As described above, in some embodiments, the channel condition may be represented by the SD-RSRP. In some embodiments, resources in the resource pool may be PSDCH resources, and the set of resources may be a set of PSDCH resources. [0040] As shown in Table 1, by way of example, when the value of SD-RSRP falls within an interval of [Xo, Xi], the channel condition is good and the set of resources corresponding thereto is a first set of PSDCH resources (which is represented as 1_PSDCH). In other words, the set of resources corresponding to the good channel condition is 1_PSDCH. When the value of SD-RSRP falls within an interval of [Xi, X ₂ ], the channel condition is moderate and the set of resources corresponding thereto is a second set of PSDCH resources (which is represented as 2_PSDCH). In other words, the set of resources corresponding to the moderate channel condition is 2_PSDCH. When the value of SD-RSRP falls within the interval of [X _n -i, Xn], the channel condition is poor and the set of resources corresponding thereto is an Ν ^ώ set of PSDCH resources (which is represented as N_PSDCH). In other words, the set of resources corresponding to the poor channel condition is N_PSDCH.

[0041] In some embodiments, the remote terminal device 120 may receive the association (for example, Table 1) from the network device 110 via radio resource control signaling (RRC). Alternatively, the association (for example, Table 1) may be pre-configured in the remote terminal device 120. In another example embodiment, the association (for example, Table 1) may be transmitted to the remote terminal device 120 by the network device 110 periodically In other embodiments, the association (for example, Table 1) may be stored in a database accessible by the remote terminal device 120.

[0042] In some embodiments, the method 300 may further include block 315. At block 315, the remote terminal device 120 transmits an indication on a lower limit channel condition to the relay terminal device 130. In some embodiments, the indication on the lower channel condition, together with the discovery request for the D2D communication, may be transmitted to the relay terminal device 130 by the remote terminal device 120. Alternatively, the remote terminal device 120 may transmit the indication on the lower limit channel condition to the relay terminal device 130 separately. In an example embodiment, the resource for transmitting the indication may be selected by the remote terminal device 120. Alternatively, the network device 110 may allocate the resource to the remote terminal device 120 for transmitting the indication.

[0043] The remote terminal device 120 may transmit the indication on the lower limit channel condition to the relay terminal device 130 in any appropriate manners. For example, in some embodiments, the remote terminal device 120 may broadcast the indication. Alternatively, the remote terminal device 120 may multicast the indication. The remote terminal device 120 may also unicast the indication. It would be appreciated that embodiments of the present disclosure are not limited in this aspect.

[0044] At block 320, the remote terminal device 120 may monitor, based on the association, a response to the discovery request from the relay terminal device 130 over the resource pool. By way of example, in some embodiments, the set of resources 1_PSDCH corresponds to a good channel condition, as shown in Table 1. The remote terminal device 120 may preferentially monitor a response to the discovery request of the D2D communication over the set of resources 1_PSDCH (which is referred to as "a first set of resources"). If the remote terminal device monitors the response to the discovery request of the D2D communication over the first set of resources successfully, it is unnecessary for the remote terminal device 120 to continue monitoring other set of resources. In this manner, the remote terminal device 120 may establish the D2D communication with the relay remote terminal device 130 with the optimum channel condition, and the D2D communication quality therebetween may be ensured accordingly. Besides, it is unnecessary to consume energy and power for the remote terminal device 120 to continue monitoring other set of resources, which is highly advantageous to increase the power efficiency of the remote terminal device 120.

[0045] In some embodiments, if the remote terminal device 120 fails to monitor the response over the first set of resources, the remote terminal device 120 may continue to monitor the set of resources 2_PSDCH (which is referred to as "a second set of resources") corresponding to the moderate channel condition. Similarly, if the remote terminal device 120 monitors the response over the second set of resources successfully, it is unnecessary for the remote terminal device 120 to continue monitoring other set of resources. If the remote terminal device 120 fails to monitor the response over the second set of resources, the remote terminal device 120 may continue to monitor other set of resources.

[0046] Fig. 4 illustrates a flowchart of an example method 400 according to some embodiments of the present disclosure.

[0047] At block 405, the relay terminal device 130 may obtain an association between the channel condition related to the discovery of the D2D communication and at least one resource in the resource pool. As described above, the channel condition related to the discovery of the D2D communication may be any appropriate information, for example, information indicating the channel fading condition2. The channel condition related to the discovery of the D2D communication may also indicate any appropriate information indicating the channel gain. [0048] Only as an example, in some embodiments, the relay terminal device 130 may obtain the above Table 1 which shows an association between the channel condition related to the discovery of the D2D communication and at least one set of resources in the resource pool. Similarly, as shown in Table 1, only as an example, when the value of SD-RSRP falls within an interval of [Xo, Xi], the channel condition is good and the set of resources corresponding thereto is a first set of PSDCH resources (which is represented as 1_PSDCH). In other words, the set of resources corresponding to the good channel condition is 1_PSDCH. When the value of SD-RSRP falls within an interval of [Xi, X ₂ ], the channel condition is moderate and the set of resources corresponding thereto is a second set of PSDCH resources (which is represented as 2_PSDCH). In other words, the set of resources corresponding to the moderate channel condition is 2_PSDCH. When the value of SD-RSRP falls within the interval of [X _n -i, Xn], the channel condition is poor and the set of resources corresponding thereto is an Ν ^ώ set of PSDCH resources (which is represented as N_PSDCH). In other words, the set of resources corresponding to the poor channel condition is N_PSDCH.

[0049] In some embodiments, the relay terminal device 130 may receive the association (for example, Table 1) from the network device 110 via radio resource control signaling (RRC). Alternatively, the association (for example, Table 1) may be pre-configured in the relay terminal device 130. In another example embodiment, the association (for example, Table 1) may be transmitted to the relay terminal device 130 periodically by the network device 110. In other embodiments, the association (for example, Table 1) may be stored in a database accessible by the remote terminal device 120.

[0050] At block 410, the relay terminal device 130 can determine the current channel condition for a discovery of D2D communication in response to receiving a discovery request of the D2D communication from the remote terminal device 120. The relay terminal device 130 may measure a channel fading condition of a discovery channel of the D2D communication between the relay terminal device 130 and the remote terminal device 120. The remote terminal device 130 may measure a channel gain of the discovery channel of the D2D communication between the relay terminal device 130 and the remote terminal device 120. Alternatively, only as an example, in some embodiments, the relay terminal device 130 may measure SD-RSRP of the discovery channel of the D2D communication between the relay terminal device 130 and the remote terminal device 120 to determine the current channel condition. For example, the relay terminal device 130 may determine that the value of SD-RSRP of the current channel is X' .

[0051] At block 415, the relay terminal device 130 may determine, based on the association, a set of resources for the response to the communication request and corresponding to the current channel in at least one set of resources. Only as an example, in some embodiments, the relay terminal device 130 may look up Table 1 to determine the set of resources corresponding to the current channel condition. For example, if the value X' of SD-RSRP of the current channel falls within an interval of [Xo, Xi], which indicates that the channel condition is good; the relay terminal device 130 may determine that the set resource for the response to the communication request is 1_PSDCH. Similarly, if the value X' of SD-RSRP of the current channel falls within an interval of [Xi, X ₂ ], which indicates that the channel condition is moderate; the relay terminal device 130 may determine that the set resource for the response to the discovery request is 2_PSDCH. If the value X' of SD-RSRP of the current channel falls within an interval of [X _n -i, X _n ], which indicates that the channel condition is poor, the relay terminal device 130 may determine that the set resource for the response to the discovery request is N_PSDCH. It would be appreciated that the relay terminal device 130 may also transmit the response not over the determined resource.

[0052] In some embodiments, the resource for transmitting the discovery request of the D2D communication may be associated with the resource responding to the request, the relay terminal device 130 may preliminarily determine a set of resources for responding to the request based on the resource receiving the discovery request, and then further determine the set of resources for responding based on the association. Alternatively, the relay terminal device 130 may preliminarily determine a set of resources responding to the request based on the association, and then further determine the set of resources for responding based on the resource receiving the discovery request.

[0053] In some embodiments, the method 400 may further include block 420. At block 420, the relay terminal device 130 may obtain an indication on a lower limit channel condition. In some embodiments, the relay terminal device 130 may receive from the remote terminal device 120 the indication on the lower limit channel condition, together with the discovery request for the D2D communication. Alternatively, the relay terminal device 130 may receive the indication on the lower limit channel condition from the remote terminal device 120 separately. In some other embodiments, the relay terminal device 130 may receive the indication on the lower limit channel condition from the network device 110.

[0054] In some embodiments, the method 400 further includes block 425. At block 425, the relay terminal device 130 may respond to the discovery request in response to the current channel condition exceeding the lower limit channel condition. In some embodiments, only as an example, assuming that the indication on the lower limit channel condition is the value Xref of SD-RSRP and the value of SD-RSRP of the current channel condition is X', the relay terminal device 130 may compare the value X' with the value X _re f. If the value X' is greater than the value X _re f, which indicates that the current channel condition is acceptable, the relay terminal device 130 may respond to the discovery request over the resource corresponding to the current channel condition. If the value X' is less than the value X _re f, which indicates that the current channel condition is poor, the relay terminal device 130 may not respond to the discovery request. As such, the relay terminal device 130 may save energy consumption. Meanwhile, interference of a PC5 interface is further reduced.

[0055] Fig. 5 illustrates a block diagram of a device 500 according to embodiments of the present disclosure. As shown in Fig. 5, the device 500 includes one or more processors 510, one or more memories 520 coupled to the processors 510, and one or more transmitters and/or receivers 540 coupled to the processors 540.

[0056] The processor 510 can be of any appropriate type applicable to the local technical environment, and for example, and without limitation, the processor 510 may include, but is not limited to, one or more general computers, dedicated computers, microprocessors, digital signal processors and processors based on multi-core processor architecture. The device 500 can include a plurality of processors, such as specific integrated circuit chips, which are temporally synchronous with the main processor.

[0057] The memory 520 can be of any appropriate type applicable to the local technical environment and can be implemented using any appropriate data storage technology, which includes, but is not limited to a non-transitory computer readable medium, a semiconductor-based storage device, magnetic storage device and system, and storage device and system.

[0058] The memory 520 stores at least a part of instructions 530. The transmitter/receiver 540 is applicable to bidirectional communication. The transmitter/receiver 540 includes at least one antenna for communication and can support optical fiber communication, but there may be several access nodes as mentioned in the present disclosure, in practice. The communication interface can represent any essential interface for communication with other network elements. [0059] The instruction 530 is assumed to include a program instruction, when executed by the associated processor 510, causing the device 500 to perform operations according to the embodiments of the present disclosure as described with reference to Fig. 3 and Fig. 4. That is, the embodiments of the present disclosure can be implemented by the processor 510 of the device 500 performed by computer software, or hardware, or a combination of software and hardware.

[0060] Fig. 6 illustrates a diagram of a device 600 according to some embodiments of the present disclosure. It would be appreciated that the device 600 can be implemented at the remote terminal device 120 side as shown in Fig. 1. As shown in Fig. 6, the device 600 (for example, the remote terminal device 120) includes a transmitting unit 610, an obtaining unit 620 and a monitoring unit 630. The transmission unit 610 is configured to transmit a discovery request for the D2D communication to the relay terminal device in the D2D communication. The obtaining unit 620 is configured to obtain an association between a channel condition related to a discovery of the D2D communication and at least one set of resources in the resource pool. The monitoring unit 630 is configured to monitor a response to the discovery request from the relay terminal device over the resource pool based on the association. [0061] Fig. 7 illustrates a block diagram of a device 700 according to some embodiments of the present disclosure. It would be appreciated that the device 700 can be implemented at the relay terminal device 130 side as shown in Fig. 1. As shown, the device 700 (for example, the relay terminal device 130) includes an obtaining unit 710, a first determining unit 720 and a second determining unit 730. The obtaining unit 710 is configured to obtain an association between a channel condition related to a discovery of the D2D communication and at least one set of resources in a resource pool. The first determining unit 720 is configured to determine the current channel condition of the discovery for the D2D communication in response to receiving a discovery request to the D2D communication from the remote terminal device. The second determining unit is configured to determine a set of resources responding to the communication request corresponding to the current channel condition in at least one set of resources based on the association.

[0062] It would be appreciated that, the device 600 and the device 700 may further include means (not shown) for performing each step in the interaction 200, method 300 and method 400 as described with reference to Figs. 1-5. The operations and features described with reference to Figs. 1-7 are also applicable to the device 600 and the device 700 as well as the means included therein, and can produce the same effect, details of which are omitted herein.

[0063] The units included in the device 600 and the device 700 may be implemented in various manners, including software, hardware, firmware or any combination thereof. In one embodiment, one or more means can be implemented using software and/or firmware, such as a machine executable instruction stored on a storage medium. Besides the machine executable instruction or as an alternative, all or a part of the means in the device 600 and the device 700 can be implemented, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-Programmable Gate Arrays (FPGAs), Application- specific Integrated Circuits (ASICs), Application- specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), and the like.

[0064] The units as shown in Figs. 6 and 7 can be partly or fully implemented as hardware modules, software modules, firmware modules or any combination thereof. Particularly, in some embodiments, the process, method or procedure as described above can be implemented by a communication device or hardware in a communication device. For example, the relay terminal device and the remote terminal device can implement the methods 300 and 400 using a transmitter, receiver, transceiver and/or processor or controller.

[0065] Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

[0066] For example, embodiments of the present disclosure can be described in the general context of machine-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media. [0067] Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server. [0068] In the context of the present disclosure, the machine readable medium may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but is not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0069] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of divide embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments dividely or in any suitable sub-combination.

[0070] Although the subject matter has been described in a language that is specific to structural features and/or method actions, it is to be understood the subject matter defined in the appended claims is not limited to the specific features or actions described above. On the contrary, the above-described specific features and actions are disclosed as an example of implementing the claims.