WO2018202212A1

WO2018202212A1 - Method and device for sidelink discovery

Info

Publication number: WO2018202212A1
Application number: PCT/CN2018/089654
Authority: WO
Inventors: Li Yang; He Wang
Original assignee: Alcatel Lucent; Nokia Shanghai Bell Co., Ltd.
Priority date: 2017-05-05
Filing date: 2018-06-01
Publication date: 2018-11-08
Also published as: CN108834107A; CN108834107B

Abstract

Embodiments of the present disclosure relate to a method and device for sidelink discovery. For example, at a relay terminal device operating on a plurality of frequency bands, a first frequency band is selected from a plurality of frequency bands to transmit a message related to sidelink discovery of a remote terminal device; and the message is transmitted at least partly in the first frequency band to enable the remote terminal device to perform sidelink discovery with the message. The corresponding method implemented at the remote terminal device and the relay terminal device and the remote terminal device capable of implementing the above method are also disclosed.

Description

METHOD AND DEVICE FOR SIDELINK DISCOVERY

FIELD

Embodiments of the present disclosure generally relate to the field of communication technology, and more specifically, to a method and device for sidelink discovery.

BACKGROUND

Currently, further enhanced device to device (feD2D) technology has been proposed in the 3 ^rd Generation Partnership Project (3GPP) standardization of Long Term Evolution (LTE) . The technology may support Internet of Things (IoT) devices with limited operating bandwidth and wearable devices for sidelink communication in relay environments. Examples of the wearable devices described above include, but are not limited to, enhanced machine type communication (eMTC) devices, narrow-band Internet of Things (NB-IoT) devices, and the like. In the LTE version 12/13/14 standard, the device-to-device (D2D) scenarios and frameworks focus on public safety or vehicle use cases. However, the related specification of the traditional D2D does not apply to feD2D. Different from the traditional D2D, in a feD2D scenario, it is desired to support the narrow-band terminal devices with low costs, low complexity and low power, such as user equipment (UE) .

For example, in a sidelink discovery process defined in the traditional D2D, an Evolved Universal Terrestrial Radio Access (E-UTRA) direct radio signals are typically used to detect and identify nearby UEs. However, in the feD2D scenario, since the remote UE (such as a wearable device) has already situated in the vicinity of the relay UE, there is no need to perform the above detection and identification process.

In addition, the physical sidelink discovery channel (PSDCH) used for the sidelink discovery in the traditional D2D is not specific to the narrow-band remote UE. For example, in the traditional D2D, the relay UE may broadcast an announcement message on the PSDCH, or transmit a response message in response to a request message from the remote UE. Regardless of which message related to sidelink discovery is transmitted, the relay UE usually uses at least one frequency band in a sub-frame for respective message transmission, and each frequency band has two physical resource blocks (PRBs) . Therefore, the remote UE needs to monitor multiple resource pools to receive the announcement message or response message transmitted by the relay UE on the PSDCH.

However, for bandwidth-limited narrow-band remote UEs, the above discovery process requires a lot of time and power to monitor the PSDCH channel, and is therefore rather inefficient. In the case where the operating band of the narrow-band remote UE does not support the frequency band used by the relay UE to transmit the message related to sidelink discovery, the narrow-band remote UE may even fail to receive the respective message. In particular, for NB-IoT devices, since they only support one PRB while the messages related to sidelink discovery are usually transmitted with two PRBs, it is impossible to obtain the messages related to sidelink discovery. Therefore, additional enhancements to the feD2D discovery process are needed to provide support for bandwidth-constrained IoT devices or wearable devices.

SUMMARY

In general, embodiments of the present disclosure provide a method and device for sidelink discovery.

In a first aspect, embodiments of the present disclosure provide a method implemented at a relay terminal device, the relay terminal device operating on a plurality of frequency bands. The method comprises: selecting, from the plurality of frequency bands, a first frequency band for transmitting a message related to sidelink discovery of a remote terminal device; and transmitting the message at least partly in the first frequency band to enable the remote terminal device to perform the sidelink discovery with the message.

In a second aspect, embodiments of the present disclosure provide a method implemented at a remote terminal device, the remote terminal device operating on one of a plurality of frequency bands. The method comprises: selecting, from the plurality of frequency bands, a first frequency band for receiving a message related to sidelink discovery from a relay terminal device, the relay terminal device operating on the plurality of frequency bands; and receiving the message at least partly in the first frequency band for performing the sidelink discovery.

In a third aspect, embodiments of the present disclosure provide a relay terminal device, comprising: a controller configured to select, from a plurality of frequency bands, a first frequency band for transmitting a message related to sidelink discovery of a remote terminal device; and a transceiver configured to transmit the message at least partly in the first frequency band to enable the remote terminal device to perform the sidelink discovery with the message.

In a fourth aspect, embodiments of the present disclosure provide a remote terminal device, comprising: a controller configured to select, from a plurality of frequency bands, a first frequency band for receiving a message related to sidelink discovery from a relay terminal device, the relay terminal device operating on the plurality of frequency bands; and a transceiver configured to receive the message at least partly in the first frequency band for performing the sidelink discovery.

In a fifth aspect, embodiments of the present disclosure provide a computer readable storage medium comprising program codes stored thereon, the program codes, when executed by an apparatus, causing the apparatus to perform the method according to the first aspect or second aspect.

Through the following depiction, it will be appreciated that according to embodiments of the present disclosure, the relay terminal device operating on a plurality of frequency bands may select one of the plurality of frequency bands to transmit message related to sidelink discovery of the remote terminal device. Accordingly, when performing sidelink discovery, the remote terminal device only needs to monitor the first frequency band without monitoring the entire operating bandwidth of the relay terminal device. In this manner, the efficiency of sidelink discovery of the remote terminal device is improved.

It will be appreciated that, the content described in the Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other features of the present disclosure will be more comprehensible with the following depiction.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the following detailed description with reference to the accompanying drawings, the above and other features, advantages and aspects of embodiments of the present disclosure will become more apparent. In the drawings, the same or similar reference symbols refer to the same or similar elements, in which:

FIG. 1 illustrates an example communication network in which embodiments of the present disclosure may be implemented;

FIG. 2 illustrates a flowchart illustrating an example method implemented at a transmitter in accordance with some embodiments of the present disclosure;

FIG. 3 illustrates an example process of dividing and distributing frequency bands in accordance with some embodiments of the present disclosure;

FIG. 4 illustrates an example communication process between a relay terminal device and a remote terminal device in accordance with some embodiments of the present disclosure;

FIG. 5 illustrates an example communication process between a relay terminal device and a remote terminal device in accordance with some other embodiments of the present disclosure;

FIG. 6 illustrates an example communication process between a relay terminal device and a remote terminal device in accordance with further embodiments of the present disclosure;

FIG. 7 illustrates a flowchart illustrating an example method in accordance with some other embodiments of the present disclosure;

FIG. 8 illustrates a block diagram illustrating an apparatus in accordance with some embodiments of the present disclosure;

FIG. 9 illustrates a block diagram illustrating an apparatus in accordance with some other embodiments of the present disclosure; and

FIG. 10 illustrates a block diagram illustrating a device suitable to implement embodiments of the present disclosure.

In all the drawings, the same or similar reference numbers refer to the same or similar elements.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will be described in the following in greater detail with reference to the drawings. Although some embodiments of the present disclosure are displayed in the drawings, it is to be understood that the present disclosure may be implemented in various manners, not limited to the embodiments set forth herein, rather, these embodiments are provided to provide a more thorough and complete understanding of the present disclosure. It is to be understood that the drawings of the present disclosure and embodiments thereof are only for illustrative purpose, rather than to limit the scope of protection of the present disclosure.

The term “network device” used herein refers to any suitable entity or device that may provide a cell or coverage so that the terminal device may access network or receive services therefrom. Examples of the network device include, for instance, a base station. The term “base station” , or BS, as used herein may 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 head (RRH) , a relay, a low power node such as a pico base station and a femto base station, and the like.

The term “terminal device” or “user equipment” as used herein refers to any entity or device that may communicate wirelessly with the network device or with each other. As an example, the terminal device may include a mobile terminal (MT) , a subscriber station (SS) , a portable subscriber station (PSS) , a mobile station (MS) , or an access terminal (AT) , the above devices mounted on a vehicle, and a machine or an appliance having communication function.

The term “remote terminal device” or “remote user equipment” (remote UE) as used herein refers to terminal devices that perform sidelink communication with the relay terminal device and further with the network device through relay of the relay terminal device. The term “relay terminal device” or “relay user equipment” (relay UE) as used herein refers to relay terminal devices that can perform sidelink communication with the remote terminal device. Through this sidelink communication, the relay terminal device may provide relay service to the remote terminal device to enable the remote terminal device to communicate with the network device by means of this relay service.

As used herein, the term “includes” 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 “one embodiment” is to be read as “at least one embodiment” ; the term “another embodiment” is to be read as “at least one another embodiment. ” The following text may also contain other explicit or implicit definitions.

As described above, the sidelink discovery process of the traditional D2D does not apply to feD2D. For example, the sidelink discovery process of the traditional D2D includes the following two modes: one mode (referred to as “mode A” ) requires the relay UE to broadcast announcement message, and the other mode (called “mode B” ) requires the relay UE to transmit response message in response to the request message from the remote UE. In mode A, the relay UE uses a plurality of frequency bands in one subframe to broadcast announcement message. Therefore, the remote UE needs to monitor the entire operating band of the relay UE to find a suitable relay UE. However, the operating frequency band of the relay UE far exceeds the range of the operating bandwidth of the narrow-band remote U E. For this reason, the narrow-band remote UE must monitor the operating band of the relay UE segment by segment in unit of its own operating band. This takes a long time and consumes a lot of energy, thus being rather inefficient. In mode B, the remote UE first transmits a request message for sidelink discovery, and then monitors to determine whether there is a relay UE that has received the request message and made a response. The remote UE usually can only perform the above monitoring on its own operating frequency band. Therefore, when the operating frequency band of the remote UE does not support the frequency band used by the relay UE, the narrow-band remote UE cannot even receive the respective message.

Besides, for NB-IoT devices, since they only support one PRB while the messages related to sidelink discovery are usually transmitted with two PRBs, it is impossible to obtain the messages related to sidelink discovery.

To at least partly solve the above and other potential problems, embodiments of the present disclosure allow the relay terminal device operating on a plurality of frequency bands to select one frequency band (referred to as “first frequency band” ) from a plurality of frequency bands to transmit messages related to sidelink discovery of the remote terminal device. Accordingly, when performing sidelink discovery, the remote terminal device only needs to monitor the first frequency band without monitoring the entire operating bandwidth of the relay terminal device, thereby improving the efficiency of sidelink discovery. Particularly for a narrow-band remote terminal device with a limited operating bandwidth, embodiments of the present disclosure greatly reduce the time and power consumption of the sidelink discovery process, thus improving the efficiency significantly.

FIG. 1 illustrates an example communication network 100 in which embodiments of the present disclosure may be implemented. The communication network 100 includes a network device 110, two relay terminal devices 120-1 and 120-2 (collectively referred to as “relay terminal device 120” ) and two remote terminal device groups 130-1 and 130-2 (collectively referred to as “remote terminal device group 130” ) . Three remote terminal devices 140-1, 140-2 and 140-3 in the remote terminal device group 130-1 are in the vicinity of the relay terminal device 120-1, and thus may perform sidelink communication with the relay terminal device 120-1, and communicate with the network device 110 owing to this. The three remote terminal devices 140-4, 140-5, and 140-6 in the remote terminal device group 130-2 are in the vicinity of the relay terminal device 120-2 and thus may perform sidelink communication with the relay terminal device 120-2, and communicate with the network device 110 owing to this. It is to be understood that the number of network devices, relay terminal devices, and remote terminal devices illustrated in FIG. 1 is for illustrative purpose only and is not meant to be limiting. Communication network 100 may include any suitable number of network devices, relay terminal devices, and remote terminal devices.

Communication in the communication network 100 may be compliant with any proper wireless communication technology and the respective communication standard. The examples of communication technology may include, but not limited to, Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , Global System for Mobile Communications (GSM) , Wireless Local Area Network (WLAN) , Worldwide Interoperability for Microwave Access (WiMAX) , Bluetooth, Zigbee technology, Machine Type Communication (MTC) , D2D, or M2M and the like. Moreover, the communication may be performed according to any suitable communication protocol, including but not limited to Transmission Control Protocol (TCP) /Internet Protocol (IP) , Hypertext Transfer Protocol (HTTP) , User Datagram Protocol (UDP) and Session Description Protocol (SDP) and the like.

The operating bandwidth of the relay terminal device 120 spans a plurality of frequency bands. Depending on the particular implementation, the remote terminal device 140 may operate on at least one of these frequency bands. In the following description, some embodiments will be discussed with the remote terminal device 140 operating in one of these frequency bands as an example. It is to be understood, however, that this is merely to enable those ordinarily skilled in the art to better understand the principles and concepts of embodiments of the present disclosure, rather than to limit the scope of the present disclosure in any way.

According to embodiments of the present disclosure, the relay terminal device 120 (for example, the relay terminal device 120-1) selects, from a plurality of frequency bands with which it operates, a first frequency band for transmitting a message related to sidelink discovery of the remote terminal device 140 in the vicinity (for example, the remote terminal devices 140-1 to 140-3) . The relay terminal device 120, in turn, transmits the message in the first frequency band. Accordingly, the remote terminal device 140 receives this message in the first frequency band and performs sidelink discovery with this message. The principles and specific embodiments of the present disclosure will be described in detail with reference to FIG. 2 to FIG. 7 from the perspective of the relay terminal device 120 and the remote terminal device 140, respectively.

FIG. 2 illustrates a flowchart of an example method 200 in accordance with some embodiments of the present disclosure. Method 200 may be implemented at the relay terminal device 120 as shown in FIG. 1. For the ease of discussion, the method 200 will be specifically described hereinafter with reference to FIG. 1.

At block 205, the relay terminal device 120 selects, from a plurality of frequency bands with which it may operate, a first frequency band for transmitting a message related to the sidelink discovery of the remote terminal device 140. This message may be any suitable message related to the sidelink discovery of the remote terminal device 140. In some embodiments, the message may include an announcement message broadcast by relay terminal device 120 which is used to inform the remote terminal device 140 in the vicinity of its existence. In some other embodiments, the message may include a response message transmitted by the relay terminal device 120 in response to the request message for sidelink discovery transmitted by the remote terminal device 140.

According to an embodiment of the present disclosure, the relay terminal device 120 may perform the selection of the first frequency band in any suitable manner. In some embodiments, the relay terminal device 120 may select one frequency band from a plurality of frequency bands by itself. At this time, the relay terminal device 120 may notify an indication of the selected frequency band to the network device 110, and then the indication is further notified to remote terminal device 140 by the network device, which enables the remote terminal device 140 to receive the message. The specific operations and processing of the remote terminal device 140 will be described in detail hereinafter with reference to FIG. 7.

In addition to performing the selection of the first frequency band by itself, in some embodiments, the relay terminal device 120 may receive the indication of the first frequency band from the network device 110 and perform the selection of the first frequency band based on the received indication. For example, the network device 110 may index multiple frequency bands available to the relay terminal device 120. Moreover, the network device 110 may allocate one frequency band for each relay terminal device 120 and transmit the index of the allocated frequency band to each relay terminal device 120. Accordingly, the relay terminal device 120 may determine the frequency band that the network device 110 allocates to it based on the received index.

One specific example is described hereinafter with reference to FIG. 3. In this example, the network device 110 divides the operating bandwidth 305 of the relay terminal device 120 into a plurality of frequency bands, and assigns one frequency band index for each frequency band. As illustrated in the figure, the network device 110 allocates a frequency band 310 for the relay terminal device 120-1, and allocates a frequency band 320 for the relay terminal device 120-2. Moreover, the network terminal device 110 transmits the corresponding frequency band index to the relay terminal devices 120-1 and 120-2.

In this case, the relay terminal devices 120-1 and 120-2 may determine that they are to transmit a message related to sidelink discovery on the

frequency bands

310 and 320 based on the respective frequency band indexes received from the network device 110, respectively. Accordingly, when a remote terminal device in the remote terminal device groups 130-1 and 130-2 is about to perform a sidelink discovery, the network device 110 may allocate indexes corresponding to

frequency bands

310 and 320 allocated to relay terminal devices 120-1 and 120-2 respectively to remote terminal device groups 130-1 and 130-2 in the vicinity. In this way, the remote terminal device groups 130-1 and 130-2 may monitor the messages from the relay terminal devices 120-1 and 120-2 in the

frequency bands

310 and 320, respectively, thereby greatly reducing the search range of the remote terminal devices.

The network device 110 may perform the division of the operating frequency band of the relay terminal device 120 in any suitable rule. In some embodiments, the network device 110 may take the bandwidth of the remote terminal device 140 in the vicinity of the relay terminal device 120 into account when performing frequency band division. For example, when the operating bandwidth of the remote terminal device 140 is 6 physical resource blocks (PRBs) , the network device 110 may divide the operating bandwidth of the relay terminal device 120 in the vicinity of the remote terminal device 140 into a plurality of frequency bands in the unit of 6 PRBs, and allocate a frequency band of 6 PRBs to each relay terminal device 120. In a case where the remote terminal device 140 is, for instance, an eMTC UE with an operating bandwidth of 1 PRB, the network device 110 may divide the operating bandwidth of the relay terminal device 120 in the vicinity of the remote terminal device 140 into a plurality of frequency bands with a width of 1 PRB.

In some embodiments, to further reduce the frequency range that the remote terminal device 140 needs to monitor and in turn to increase the monitoring efficiency, the network device 110 may dynamically perform the above frequency band division for a certain relay terminal device 120. For example. for the relay terminal device 120-1, when the operating bandwidth of the remote terminal devices 140-1 to 140-3 in the vicinity thereof is 6 PRBs, the network device 110 may divide the operating bandwidth of the relay terminal device 120-1 into a plurality of frequency bands with a width of 6 PRBs. When the remote terminal devices 140-1 to 140-3 in the vicinity of the relay terminal device 120-1 are eMTC UEs with an operating bandwidth of 1 PRB, the network device 110 may re-divide the operating bandwidth into a plurality of frequency bands of a width of 1 PRB, and re-allocate frequency bands for the relay terminal device 120-1.

In addition to receiving an indication of the first frequency band from the network device 110, in some other embodiments, the relay terminal device 120 may also receive the indication from the remote terminal device 140. In an embodiment where the relay terminal device 120 transmits, in response to receiving a request message for sidelink discovery from the remote terminal device 140, a response message as a message related to sidelink discovery, the request message may indicate the first frequency band. The relay terminal device 120 may in turn select the first frequency band from the plurality of frequency bands based on the received request message. It is possible to realize indication of the first frequency band through a request message in any suitable manner. As an example, the indication of the first frequency band may be included in the request message. As an alternative, a certain mode of the request message may also correspond to a certain frequency band. In this way, the relay terminal device 120 may determine the first frequency band accordingly after receiving the request message. Examples in this regard will be described hereinafter in detail.

Continuing to refer to FIG. 2, after the relay terminal device 120 selects the first frequency band, at block 210, the relay terminal device 120 at least partly transmits a message related to sidelink discovery of the remote terminal device 140 in the first frequency band to enable the remote terminal device 140 to perform sidelink discovery with this message. In the embodiment where the message related to sidelink discovery is implemented as an announcement message of the relay terminal device 120, the relay terminal device 120 may broadcast the announcement message in the first frequency band.

As described above, there is only one PRB in the operating bandwidth of some remote terminal devices 140 (such as eMTC UEs) . However, PSDCH transmission packets used by the message related to sidelink discovery e.g. the announcement message or response message, often occupy more than one PRB, e.g. two PRBs, in one subframe. In order to further improve the efficiency of sidelink discovery of the remote terminal device 140 (especially the eMTC UE) , in some embodiments, it is possible to compress the message that needs to occupy multiple PRBs in the manner of reducing the size or improving the modulation and coding scheme (MCS) , such that the message is adapted to be transmitted in one PRB. This approach needs to be coordinated through the high level of the system.

In order to further increase system efficiency, in some embodiments, it is possible to divide the message related to sidelink discovery into a plurality of message segments, each of which is transmitted within a period of time (such as a subframe) using one resource unit (such as a PRB) . It is to be understood that the period of time may be of any suitable duration, and the resource unit may have any proper frequency bandwidth. The scope of the present disclosure is not limited in this regard.

In embodiments where the relay terminal device 120 broadcasts an announcement message, the announcement message may include a plurality of announcement message segments. In this case, the relay terminal device 120 may broadcast one announcement message segment (referred to as “first announcement message segment” ) of a plurality of announcement message segments in the first subframe.

To facilitate remote terminal device 140 receiving other announcement message segments, in some embodiments, the relay terminal device 120 may use a first announcement message segment to indicate the frequency band (referred to as “second frequency band” ) used by the subsequent announcement message segment (referred to as “second announcement message segment” ) . For example, the relay terminal device 120 may select, from a plurality of frequency bands, a second frequency band to be used for broadcasting the second announcement message segment. The relay terminal device 120 may in turn use the first announcement message segment to indicate the second frequency band when the first announcement message segment is broadcast in the first frequency band.

It is possible to realize indication of the second frequency band with the first announcement message segment in any proper manner. In some embodiments, the indication of the second frequency band may be contained in the first annonncement message segment. For example, some bits of an announcement message segment may be used alone for this indication. It is to be understood that other ways of indication are also feasible.

According to an embodiment of the present disclosure, the announcement message broadcast by the relay terminal device 120 may include the original announcement message and a duplicate of the original message. In the context of the present disclosure, “duplicate” refers to a copy of a message, which may include full copying, for example using different channel coding. By transmitting multiple duplicates of the message, the transmit energy may be increased, so as to increase the probability that the receiver correctly detects the signal, thereby enhancing the transmission coverage.

A specific example in which the relay terminal device 120 broadcasts a plurality of announcement message segments is described hereinafter with reference to FIG. 4. As illustrated, the announcement message broadcast by the relay terminal device 120 includes the original announcement message and a duplicate of the original message. The original announcement message includes two

announcement message segments

405 and 410, while the duplicate of the announcement message includes an announcement message segment 415 and other announcement message segments (not shown) .

In this example, the relay terminal device 120 first selects a frequency band 310 for broadcasting the announcement message segment 405. The relay terminal device 120 also selects another frequency band (not shown) for broadcasting the announcement message segment 410. The relay terminal device 120 in turn broadcasts the announcement message segment 405 in the frequency band 310, and includes an indication 420 of another frequency band used by the announcement message segment 410 in the announcement message segment 405. As illustrated, the announcement message segment 410 broadcast by the relay terminal device 120 contains an indication 425 of the frequency band to be used by the announcement message segment 415 in the duplicate of the announcement message, and contains an indication 430 of the frequency band used for subsequent announcement message segment in the announcement message segment 415.

Accordingly, the remote terminal device 140 may obtain respective

frequency band indications

420, 425 and 430 from the received

announcement message segments

405, 410 and 415 broadcast by the relay terminal device 120. The remote terminal device 140 may in turn receive the respective messages on the indicated frequency bands. The respective operations of the remote terminal device 140 will be described in detail hereinafter with reference to FIG. 7.

As described above, in the embodiment in which the relay terminal device 120 transmits, in response to receiving a request message for sidelink discovery from the remote terminal device 140, a response message as a message related to sidelink discovery, the request message may indicate the first frequency band. A specific example will be described hereinafter with reference to FIG. 5. As shown in the figure, the remote terminal device 140 may transmit a request message 505 towards the relay terminal device 120 in the vicinity when performing the sidelink discovery, the request message 505 including an indication 510 of the frequency band for the relay terminal device 120 to transmit the response message. The remote terminal device 140 may use any suitable frequency band to transmit the request message 505. A specific example in this regard will be described in detail hereinafter.

After receiving the request message 505, the relay terminal device 120 may obtain a frequency band indication 510 from the request message 505. If the relay terminal device 120 determines that it is possible to provide relay service to the network device 110 for the remote terminal device 140, the first frequency band may be selected based on the indication 510 from the plurality of frequency bands that it operates, and the response message 515 for the request message 505 is in turn transmitted towards the remote terminal device 140 in the first frequency band. In this manner, the remote terminal device 140 may only monitor the desired frequency band when the response message for the relay terminal device 120 is received.

Although both the announcement message and the response message of the relay terminal device 120 are described above as transmitted in the first frequency band, it is to be understood that this is for illustrative purpose only and is not intended to be limiting in any manner. According to embodiments of the present disclosure, the announcement message and the response message of the relay terminal device 120 may be transmitted in different frequency bands.

Similar to the announcement message, the request message transmitted by the remote terminal device 140 and the response message transmitted by the relay terminal device 120 may also include multiple message segments to further improve the efficiency of sidelink discovery of the remote terminal device 140 with limited operating bandwidth (for instance, eMTC UE with a bandwidth of only one PRB) . Similarly, the request message may include the original request message and a duplicate of the original request message while the response message may include the original response message and a duplicate of the original response message.

When the request message includes multiple request message segments, one of the multiple request message segments (referred to as a “first request message segment” ) may indicate the frequency band (referred to as “third frequency band” ) used by the subsequent request message segment (referred to as a “second request message segment” ) . After the relay terminal device 120 receives a first request message segment from the remote terminal device 140, a fourth frequency band may be determined based on the first request message segment, and a second request message segment may in turn be received from the remote terminal device 140 in the fourth frequency band.

If there are other request message segments after the second request message segment, the second request message segment may indicate subsequent request message segments. Alternatively, the second request message segment may indicate the frequency band on which the remote terminal device 140 expects to receive the response message, such as the first frequency band. Accordingly, the relay terminal device 120 may determine the first frequency band based on the received second response message segment, and transmit one response message segment (referred to as “first response message segment” ) of the plurality of response message segments in the first frequency band. Likewise, the first response message segment may indicate the frequency band (referred to as “fourth frequency band” ) used by the subsequent response message segment (referred to as “second response message segment” ) . In this way, the remote terminal device 140 can obtain the information of the frequency band used by the relay terminal device 120 to transmit each response message segment, so that each response message segment can be monitored in the respective frequency band, which greatly improves the efficiency of sidelink discovery.

A specific example will be discussed hereinafter with reference to FIG. 6. As shown in the figure, the request message transmitted by the remote terminal device 140-1 includes two

request message segments

605 and 610. An indication 615 of the frequency band for transmitting the request message segment 610 is included in the request message segment 605. Accordingly, the relay terminal device 120 may determine the frequency band to be used by the request message segment 610 based on an indication 615 contained in the received request message segment 605, and in turn receive the request message segment 610 in the respective frequency band.

The response message for the request message transmitted by the relay terminal device 120 also includes two message segments, namely,

response message segments

620 and 625. In this example, the request message segment 610 contains an indication 630 of the frequency band to be used for the response message segment 625. Accordingly, after receiving the request message segment 610, the relay terminal device 120 may determine the frequency band for transmitting the response message segment 620 based on the indication 630 contained therein, and transmit the response message segment 620 on the frequency band. As illustrated, the response message segment 620 contains an indication 635 of the frequency band to be used for the response message segment 625 in order to inform the remote terminal device 140 on which frequency band the response message segment 625 is received. In this way, the efficiency of the sidelink discovery process may be improved.

FIG. 7 shows a flowchart illustrating an example method 700 in accordance with some embodiments of the present disclosure. The method 700 may be implemented at the remote terminal device 140 as shown in FIG. 1. For ease of discussion, method 700 will be described in detail hereinafter with reference to FIG. 1.

As illustrated, at block 705, the remote terminal device 140 operating on one of a plurality of frequency bands selects, from a plurality of frequency bands, a first frequency band for receiving messages related to sidelink discovery from the relay terminal device 120. According to embodiments of the present disclosure, the relay terminal device operates on a plurality of frequency bands.

The remote terminal device 140 may perform the selection of the first frequency band in any suitable manner. In an embodiment where the message related to sidelink discovery is an announcement message broadcast by the relay terminal device 120, the remote terminal device 140 may receive the indication of the first frequency band from the network device 110, and based on the received indication, select the first frequency band from a plurality of frequency bands. In an embodiment where the message is a response message transmitted by the relay terminal device 120 in response to the request message transmitted by the remote terminal device 140, the remote terminal device 140 may select the first frequency band by itself.

It is to be understood that the above two alternatives are merely illustrative rather than limiting and other ways are also feasible. For example, when the relay terminal device 120 transmits, in response to a request message transmitted by the remote terminal device 140, a response message as a message related to sidelink discovery, the remote terminal device 140 may also select the first frequency band based on the indication of the network device 110.

After selecting the first frequency band, at block 710, the remote terminal device 140 receives the message related to sidelink discovery at least partly in the first frequency band for performing sidelink discovery. In an embodiment where the message is an announcement message broadcast by the relay terminal device 120, the remote terminal device 140 may receive the announcement message at least partly in the first frequency band.

In some embodiments, the announcement message may include a plurality of announcement message segments. In these embodiments, the remote terminal device 140 may receive the first announcement message segment in the plurality of announcement message segments in the first frequency band. The first announcement message segment may indicate a second frequency band to be used by the relay terminal device 120 to broadcast the second announcement message segment of the plurality of announcement message segments. The remote terminal device 140 may in turn determine the second frequency band based on the first announcement message segment and receive the second announcement message segment in the second frequency band.

In the embodiment where the message related to sidelink discovery is a response message transmitted by the relay terminal device 120 in response to the request message transmitted by the remote terminal device 140, the remote terminal device 140 may also transmit a request message for the sidelink discovery towards the relay terminal device 120. The request message may at least indicate the first frequency band. The remote terminal device 140 may in turn receive a response message for the request message from the relay terminal device at least partly in the first frequency band.

In some embodiments, the request message includes a plurality of request message segments. In these embodiments, the remote terminal device 140 may transmit the first request message segment in the plurality of request message segments towards the relay terminal device 120. The first request message segment indicates a third frequency band of a plurality of frequency bands. The remote terminal device 140 may in turn transmit the second request message segment in the plurality of request message segments to the relay terminal device 120 on the third frequency band, wherein the second request message segment indicates the first frequency band.

In some embodiments, the response message includes a plurality of response message segments. In these embodiments, the remote terminal device 140 may receive the first response message segment in the plurality of response message segments from the relay terminal device 120 in the first frequency band. The first response message segment indicates a fourth frequency band of the plurality of frequency bands, wherein the second response message segment of the plurality of response message segments is to be transmitted in the fourth frequency band.

It is to be understood that the remote terminal device 140 may perform the sidelink discovery process described above using any of the current sidelink discovery technology, or any sidelink discovery technology to be developed in the future, and the scope of the present disclosure is not limited in this respect.

It is also to be understood that the operations performed by the relay terminal device 120 described above in conjunction with schematic diagrams FIG. 1 to FIG. 6 and the related features are also applicable to the method 700 performed by the remote terminal device 140 and have the same effect. The specific details will not be repeated.

FIG. 8 shows a block diagram of an apparatus 800 in accordance with some embodiments of the present disclosure. It is to be understood that the apparatus 800 may be implemented at the side of the relay terminal device 120 shown in FIG. 1. As shown in FIG. 8, the apparatus 800 (for example, the relay terminal device 120) includes a first selection unit 805 and a transmission unit 810. The first selection unit 805 is configured to select a first frequency band from among a plurality of frequency bands for transmitting a message related to sidelink discovery of the remote terminal device. The transmission unit 810 is configured to transmit the message at least partly in the first frequency band to enable the remote terminal device to perform sidelink discovery with the message.

FIG. 9 shows a block diagram of an apparatus 900 in accordance with some embodiments of the present disclosure. It is to be understood that the apparatus 900 may be implemented at a side of the remote terminal device 140 shown in FIG. 1. As illustrated, the apparatus 900 (such as the remote terminal device 140) includes a second selection unit 905 and a receiving unit 910. The second selection unit 905 is configured to select from a plurality of frequency bands a first frequency band for receiving a message related to sidelink discovery from the relay terminal device, wherein the relay terminal device operates on a plurality of frequency bands. The receiving unit 910 is configured to receive the message at least partly in the first frequency band for performing the sidelink discovery.

It shall be appreciated that the apparatus 800 and apparatus 900 may further include units (not shown) for performing each step of the method 200 and method 700 depicted above with reference to FIGS. 1-7. The operations and features depicted with reference to FIGS. 1-7 are likewise applicable to the apparatus 800 and apparatus 900 and the units contained therein and have the same effect. The details will not be repeated herein.

The units included in the

apparatuses

800 and 900 may be implemented in various manners, including software, hardware, firmware, or any combination thereof. In one embodiment, one or more modules may be implemented using software and/or firmware, for example, machine-executable instructions stored on the storage medium. In addition to or instead of machine-executable instructions, parts or all of the modules in the

apparatuses

800 and 900 may be implemented, at least in part, by one or more hardware logic components. As an 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.

The units shown in FIGS. 8 and 9 may be implemented, partially or entirely, as hardware modules, software modules, firmware modules or any combination thereof. In particular, in some embodiments, the flows, methods or processes described above may be implemented by a communication device or hardware in a communication device. For example, the relay terminal device and remote terminal device may implement the

methods

200 and 700 by means of its transmitter, receiver, transceiver and/or processor or controller.

FIG. 10 shows a block diagram of a device 1000 applicable to implement embodiments of the present disclosure. The device 1000 may be used to implement the relay terminal device 120 or remote terminal device 140 shown in FIG. 1.

As shown, the device 1000 includes a controller 1010. The controller 1010 controls operations and functions of the device 1000. For example, in some embodiments, the controller 1010 may execute various operations by means of instructions 1030 stored in a memory 1020 coupled to the controller 1010. The memory 1020 may be of any appropriate type suitable for a local technical environment, and may be implemented using any suitable data storage technique, including without limitation to, a semiconductor based memory device, a magnetic memory device and system, an optical memory device and system. Although only one memory unit is shown in FIG. 10, there may be a plurality of physically different memory units in the device 1000.

The controller 1010 may be of any suitable type suitable for a local technical environment, and may include without limitation to, one or more of a general-purpose computer, a special purpose computer, a microcontroller, a digital signal processor (DSP) , and a multi-core controller architecture based on controllers. The device 1000 may also include a plurality of controllers 1010. The controller 1010 is coupled to a transceiver 1040 and the transceiver 1040 may enable information receiving and transmitting by means of one or more antennas 1050 and/or other components.

When the device 1000 acts as the relay terminal device, the controller 1010 and the transceiver 1040 may operate in cooperation to implement the method 200 described above with reference to FIGS. 1-6. When the device 1000 acts as the remote terminal device, the controller 1010 and the transceiver 1040 may operate in cooperation to implement the method 700 described above with reference to FIG. 7. All features described above with reference to FIGS. 1 to 7 are applicable to the device 1000 and will not be repeated herein.

Generally, various example embodiments of the present disclosure may be implemented in hardware, special purpose circuits, software, logic or any combinations thereof. Some aspects may be implemented in hardware while other aspects may be implemented in firmware or software executed by controllers, microprocessors or other computing devices. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method 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.

As an example, embodiments of the present disclosure may be described in the context of machine-executable instructions, which is included in program modules executed in devices on a target physical or virtual processor, for example. In general, program modules comprise routines, programs, libraries, objects, classes, components, data structures, and the like, that perform particular tasks or implement particular abstract data structures. 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.

Computer program codes for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. The computer program codes may be provided to a processor of a general purpose computer, a special purpose computer or other programmable data processing apparatuses, such that the program codes, when executed by the computer or other programmable data processing apparatuses, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program codes may be executed 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.

In the context of the present disclosure, a machine-readable medium may be any tangible medium that contains or stores programs for or related to an instruction executing system, apparatus or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium and may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus or device, or any suitable combination thereof. 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 thereof.

Furthermore, although operations are depicted in a particular order, it is to be understood that such operations are not required to 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 might 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 illustration of features that may be specific to particular embodiments. Certain features that are described in the context of separate 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 separately or in any suitable sub-combination.

Although the present disclosure has been described in languages specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A method implemented at a relay terminal device, the relay terminal device operating on a plurality of frequency bands, the method comprising:

selecting, from the plurality of frequency bands, a first frequency band for transmitting a message related to sidelink discovery of a remote terminal device; and

transmitting the message at least partly in the first frequency band to enable the remote terminal device to perform the sidelink discovery with the message.
The method according to Claim 1, wherein selecting the first frequency band comprises:

receiving, from a network device, an indication of the first frequency band; and

selecting, based on the received indication, the first frequency band from the plurality of frequency bands.
The method according to Claim 2, wherein transmitting the message at least partly in the first frequency band comprises:

broadcasting, at least partly in the first frequency band, an announcement message to be used by the remote terminal device for the sidelink discovery.
The method according to Claim 3, wherein the announcement message includes a plurality of announcement message segments, and broadcasting the announcement message comprises:

broadcasting a first announcement message segment of the plurality of announcement message segments in the first frequency band.
The method according to Claim 4, wherein broadcasting the first announcement message segment comprises:

selecting, from the plurality of frequency bands, a second frequency band for broadcasting a second announcement message segment of the plurality of announcement message segments; and

broadcasting the first announcement message segment in the first frequency band, the first announcement message segment indicating the second frequency band.
The method according to Claim 1, wherein selecting the first frequency band comprises:

receiving, from the remote terminal device, a request message for the sidelink discovery, the request message at least indicating the first frequency band; and

selecting, based on the received request message, the first frequency band from the plurality of frequency bands.
The method according to Claim 6, wherein transmitting the message at least partly in the first frequency band comprises:

transmitting, a response message for the request message towards the remote terminal device at least partly in the first frequency band.
The method according to Claim 7, wherein the request message includes a plurality of message segments, and receiving the request message comprises:

receiving, from the remote terminal device, a first request message segment of the plurality of request message segments, the first request message segment indicating a third frequency band of the plurality of frequency bands;

determining the third frequency band based on the received first request message segment; and

receiving a second request message segment of the plurality of request message segments from the remote terminal device in the third frequency band, the second request segment indicating the first frequency band.
The method according to Claim 8, wherein the response message includes a plurality of response message segments, and transmitting the response message at least partly in the first frequency band comprises:

transmitting, in the first frequency band, a first response message segment of the plurality of response message segments towards the remote terminal device, the first response message segment indicating a fourth frequency band of the plurality of frequency bands, a second response message segment of the plurality of response message segments to be transmitted on the fourth frequency band.
A method implemented at a remote terminal device, the remote terminal device operating on one of a plurality of frequency bands, the method comprising:

selecting, from the plurality of frequency bands, a first frequency band for receiving a message related to sidelink discovery from a relay terminal device, the relay terminal device operating on the plurality of frequency bands; and

receiving the message at least partly in the first frequency band for performing the sidelink discovery.
The method according to Claim 10, wherein selecting the first frequency band comprises:

receiving, from a network device, an indication of the first frequency band; and

selecting, based on the received indication, the first frequency band from the plurality of frequency bands.
The method according to Claim 11, wherein receiving the message at least partly in the first frequency band comprises:

receiving an announcement message broadcast by the relay terminal device at least partly in the first frequency band.
The method according to Claim 12, wherein the announcement message includes a plurality of announcement message segments, and receiving the announcement message at least partly in the first frequency band comprises:

receiving, in the first frequency band, a first announcement message segment of the plurality of announcement message segments, the first announcement message segment indicating a second frequency band of the plurality of frequency bands that is to be used by the relay terminal device for broadcasting a second announcement message segment of the plurality of announcement message segments;

determining the second frequency band based on the first announcement message segment; and

receiving the second announcement message segment in the second frequency band.
The method according to Claim 10, further comprising:

transmitting, towards the relay terminal device, a request message for the sidelink discovery, the request message at least indicating the first frequency band.
The method according to Claim 14, wherein receiving the message at least partly in the first frequency band comprises:

receiving a response message for the request message from the relay terminal device at least partly in the first frequency band.
The method according to Claim 15, wherein the request message includes a plurality of request message segments, and transmitting the request message comprises:

transmitting a first request message segment of the plurality of request message segments towards the relay terminal device, the first request message segment indicating a third frequency band of the plurality of frequency bands; and

transmitting, towards the relay terminal device, a second request message segment of the plurality of request message segments on the third frequency band, the second request message segment indicating the first frequency band.
The method according to Claim 16, wherein the response message includes a plurality of response message segments, and receiving the response message at least partly in the first frequency band comprises:

receiving, in the first frequency band, a first response message segment of the plurality of response message segments from the relay terminal device, the first response message segment indicating a fourth frequency band of the plurality of frequency bands, a second response message segment of the plurality of response message segments to be transmitted on the fourth frequency band.
A relay terminal device, comprising:

a controller configured to select, from a plurality of frequency bands, a first frequency band for transmitting a message related to sidelink discovery of a remote terminal device; and

a transceiver configured to transmit the message at least partly in the first frequency band to enable the remote terminal device to perform the sidelink discovery with the message.
The relay terminal device according to Claim 18, wherein the transceiver is further configured to receive an indication of the first frequency band from a network device, and

wherein the controller is configured to select the first frequency band from the plurality of frequency bands based on the received indication.
The relay terminal device according to Claim 19, wherein the transceiver is configured to:

broadcast, at least partly in the first frequency band, an announcement message to be used by the remote terminal device for the sidelink discovery.
The relay terminal device according to Claim 20, wherein the announcement message includes a plurality of announcement message segments, and the transceiver is configured to:

broadcast a first announcement message segment of the plurality of announcement message segments in the first frequency band.
The relay terminal device according to Claim 21, wherein the controller is further configured to select, from the plurality of frequency bands, a second frequency band for broadcasting a second announcement message segment of the plurality of announcement message segments; and

wherein the transceiver is configured to broadcast the first announcement message segment in the first frequency band, the first announcement message segment indicating the second frequency band.
The relay terminal device according to Claim 18, wherein the transceiver is further configured to receive, from the remote terminal device, a request message for the sidelink discovery, the request message at least indicating the first frequency band; and

wherein the controller is configured to select the first frequency band from the plurality of frequency bands based on the received request message.
The relay terminal device according to Claim 23, wherein the transceiver is configured to:

transmit a response message for the request message to the remote terminal device at least partly in the first frequency band.
The relay terminal device according to Claim 24, wherein the request message includes a plurality of request message segments, and the transceiver is further configured to: receive, from the remote terminal device, a first request message segment of the plurality of request message segments, the first request message segment indicating a third frequency band of the plurality of frequency bands;

wherein the controller is further configured to determine the third frequency band based on the received first request message segment; and

wherein the transceiver is configured to receive, in the third frequency band, a second request message segment of the plurality of request message segments from the remote terminal device, the second request segment indicating the first frequency band.
The relay terminal device according to Claim 25, wherein the response message includes a plurality of response message segments, and the transceiver is configured to:

transmit, in the first frequency band, a first response message segment of the plurality of response message segments towards the remote terminal device, the first response message segment indicating a fourth frequency band of the plurality of frequency bands, a second response message segment of the plurality of response message segments to be transmitted on the fourth frequency band.
A remote terminal device, comprising:

a controller configured to select, from a plurality of frequency bands, a first frequency band for receiving a message related to sidelink discovery from a relay terminal device, the relay terminal device operating on the plurality of frequency bands; and

a transceiver configured to receive the message at least partly in the first frequency band for performing the sidelink discovery.
The remote terminal device according to Claim 27, wherein the transceiver is further configured to receive an indication of the first frequency band from a network device; and

wherein the controller is configured to select the first frequency band from the plurality of frequency bands based on the received indication.
The remote terminal device according to Claim 28, wherein the transceiver is configured to:

receive an announcement message broadcast by the relay terminal device at least partly in the first frequency band.
The remote terminal device according to Claim 29, wherein the announcement message includes a plurality of announcement message segments, and the transceiver is configured to:

receive, in the first frequency band, a first announcement message segment of the plurality of announcement message segments, the first announcement message segment indicating a second frequency band of the plurality of frequency bands that is to be used by the relay terminal device for broadcasting a second announcement message segment of the plurality of announcement message segments;

wherein the controller is further configured to determine the second frequency band based on the first announcement message segment; and

wherein the transceiver is further configured to receive the second announcement message segment in the second frequency band.
The remote terminal device according to Claim 27, wherein the transceiver is further configured to:

transmit a request message for the sidelink discovery towards the relay terminal device, the request message at least indicating the first frequency band.
The remote terminal device according to Claim 31, wherein the transceiver is configured to:

receive a response message for the request message from the relay terminal device at least partly in the first frequency band.
The remote terminal device according to Claim 32, wherein the request message includes a plurality of request message segments, and the transceiver is configured to:

transmit a first request message segment of the plurality of request message segments towards the relay terminal device, the first request message segment indicating a third frequency band of the plurality of frequency bands; and

transmit, towards the relay terminal device, a second request message segment of the plurality of request message segments on the third frequency band, the second request message segment indicating the first frequency band.
The remote terminal device according to Claim 33, wherein the response message includes a plurality of response message segments, and the transceiver is configured to:

receive, in the first frequency band, a first response message segment of the plurality of response message segments from the relay terminal device, the first response message segment indicating a fourth frequency band of the plurality of frequency bands, a second response message segment of the plurality of response message segments to be transmitted on the fourth frequency band.
A computer readable storage medium comprising program codes stored thereon, the program codes, when executed by an apparatus, causing the apparatus to perform the method according to any of Claims 1-9.
A computer readable storage medium comprising program codes stored thereon, the program codes, when executed by an apparatus, causing the apparatus to perform the method according to any of Claims 10-17.