WO2013107004A1

WO2013107004A1 - Method and apparatus for facilitating concurrent occupation of a channel

Info

Publication number: WO2013107004A1
Application number: PCT/CN2012/070521
Authority: WO
Inventors: Haifeng Wang; Zhenhong Li; Ting Zhou; Jing Xu
Original assignee: Renesas Mobile Corp
Current assignee: Renesas Electronics Corp
Priority date: 2012-01-18
Filing date: 2012-01-18
Publication date: 2013-07-25
Anticipated expiration: 2014-07-18

Abstract

A method is provided for facilitating concurrent occupation of a channel. The method may include determining, at a first terminal that is a member of a first device-to- device (D2D) communication group, that the first terminal has not heard a clear to send message within a predefined period of time following the first terminal hearing a message requesting to send data on a channel sent by a second terminal that is a member of a second D2D communication group. The method may further include determining, responsive to determining that the first terminal has not heard a clear to send message within the predefined period of time following the first terminal hearing the message requesting to send data on the channel, to format and send a D2D shared band data request (DSBDR) message to be sent to a third terminal. A corresponding apparatus and computer program product are also provided.

Description

METHOD AND APPARATUS FOR FACILITATING

CONCURRENT OCCUPATION OF A CHANNEL

TECHNOLOGICAL FIELD

[0001] Embodiments of the present invention relate generally to wireless communication technology and, more particularly, relate to an apparatus, method and computer program product for facilitating concurrent occupation of a channel.

BACKGROUND

[0002] The modern communications era has brought about a tremendous expansion of wireless network technology, driven by consumer demands. This expansion of wireless and mobile networking technologies have addressed related consumer demands, while providing more flexibility and immediacy of information transfer and providing convenience to users.

[0003] Current and future networking technologies continue to facilitate ease of information transfer and convenience to users. In order to provide easier or faster information transfer and convenience, telecommunication industry service providers are developing improvements to existing networks. One ongoing area of development in networking and communication technology is the development of device-to-device (D2D) communication technologies. D2D communication technologies may use radio resources of a hosting cellular system, but allow two computing devices, such as mobile terminals (also referred to as user equipment (UE)), to communicate directly with each other without routing their communications through components of the cellular system.

[0004] Use of D2D communication may offer several advantages. For example, the direct communication link between mobile terminals engaged in D2D communication may result in reduced end-to-end delay time for data exchanged between the terminals as compared to indirect communication via cellular system components. Further, since communications may be offloaded from the cellular network to D2D communication links, network load may be reduced. Additional benefits of D2D communication may include improved local area coverage, improved serving network resource efficiency, and conservation of transmission power by both UEs and network access points. Additionally, D2D communication may support a variety of end user services, such as peer-to-peer applications, head-to-head gaming applications, collaborative applications, and/or the like that may be used by users of mobile terminals within close proximity of each other. [0005] While usage of D2D communication offers several advantages, coexistence of mobile terminals using D2D communication on license-exempt bands, such as Industrial, Scientific, Medical (ISM) bands, with other users of the license- exempt bands may be problematic. In this regard, ISM bands are widely used by wireless systems, such as Wireless Local Area Networks (WLANs). Accordingly, coordination of D2D communication to avoid interference with coexisting WLAN systems while making efficient use of license-exempt bands is an ongoing area of development.

BRIEF SUMMARY OF EXAMPLE EMBODIMENTS

[0006] Methods, apparatuses and computer program products are provided herein for facilitating concurrent occupation of a channel. Embodiments provided herein may provide several advantages to network providers, wireless service providers, computing devices, and computing device users. In this regard, some example embodiments improve the spatial reuse of a communication medium while avoiding inter-device interference. More particularly, some example embodiments facilitate concurrent occupation of a channel by multiple D2D communication groups such that two terminals within carrier-sensing range of each other may transmit simultaneously in the event that their transmissions do not mutually interfere. Accordingly, some example embodiments provide for improved channel efficiency and capacity by allowing concurrent occupation of a channel in the event that there is a hidden terminal and/or an exposed terminal. Some example embodiments are further operational in a manner compliant to conventional channel contention mechanisms, such as the WLAN Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)

mechanism so as to provide fairness between cellular systems and WLAN systems. Some example embodiments additionally save cellular scheduling signaling overhead and latency delay by providing for concurrent channel use and channel reuse.

[0007] In a first example embodiment, a method is provided, which may comprise determining, at a first terminal that is a member of a first D2D communication group, that the first terminal has not heard a clear to send message within a predefined period of time following the first terminal hearing a message requesting to send data on a channel sent by a second terminal that is a member of a second D2D communication group. The method of this example embodiment may further comprise determining, responsive to determining that the first terminal has not heard a clear to send message within the predefined period of time following the first terminal hearing the message requesting to send data on the channel, to format and send a D2D shared band data request (DSBDR) message to a third terminal requesting the third terminal to send data to the first terminal over the channel during a period of time during which the channel is reserved by the second terminal. The third terminal of this example embodiment may be a member of the first D2D communication group. The method of the first example embodiment provides for improved channel efficiency and capacity by allowing concurrent occupation of a channel in the event that there is a hidden terminal and/or an exposed terminal.

[0008] In another example embodiment, an apparatus comprising at least one processor and at least one memory including computer program code is provided. The at least one memory and the computer program code may be configured to, with the at least one processor, cause the apparatus of this example embodiment to at least determine, at a first terminal that is a member of a first D2D communication group, that the first terminal has not heard a clear to send message within a predefined period of time following the first terminal hearing a message requesting to send data on a channel sent by a second terminal that is a member of a second D2D communication group. The at least one memory and the computer program code may be configured to, with the at least one processor, further cause the apparatus of this example embodiment to determine, responsive to determining that the first terminal has not heard a clear to send message within the predefined period of time following the first terminal hearing the message requesting to send data on the channel, to format and send a DSBDR message to a third terminal requesting the third terminal to send data to the first terminal over the channel during a period of time during which the channel is reserved by the second terminal. The third terminal of this example embodiment may be a member of the first D2D communication group. The apparatus of this example embodiment provides for improved channel efficiency and capacity by allowing concurrent occupation of a channel in the event that there is a hidden terminal and/or an exposed terminal.

[0009] In a further example embodiment, a computer program product comprising at least one non-transitory computer-readable storage medium having computer-readable program code stored therein is provided. The computer-readable program code may include instructions configured to cause an apparatus to determine, at a first terminal that is a member of a first D2D communication group, that the first terminal has not heard a clear to send message within a predefined period of time following the first terminal hearing a message requesting to send data on a channel sent by a second terminal that is a member of a second D2D communication group. The computer-readable program code may further include instructions configured to cause the apparatus to determine, responsive to determining that the first terminal has not heard a clear to send message within the predefined period of time following the first terminal hearing the message requesting to send data on the channel, to format and send a DSBDR message to a third terminal requesting the third terminal to send data to the first terminal over the channel during a period of time during which the channel is reserved by the second terminal. The third terminal of this example embodiment may be a member of the first D2D communication group. The computer program product of this example embodiment provides for improved channel efficiency and capacity by allowing concurrent occupation of a channel in the event that there is a hidden terminal and/or an exposed terminal.

[0010] In yet another example embodiment, an apparatus is provided, which may comprise means for determining, at a first terminal that is a member of a first D2D communication group, that the first terminal has not heard a clear to send message within a predefined period of time following the first terminal hearing a message requesting to send data on a channel sent by a second terminal that is a member of a second D2D

communication group. The apparatus of this example embodiment may further comprise means for determining, responsive to determining that the first terminal has not heard a clear to send message within the predefined period of time following the first terminal hearing the message requesting to send data on the channel, to format and send a DSBDR message to a third terminal requesting the third terminal to send data to the first terminal over the channel during a period of time during which the channel is reserved by the second terminal. The third terminal of this example embodiment may be a member of the first D2D communication group. The apparatus of this example embodiment provides for improved channel efficiency and capacity by allowing concurrent occupation of a channel in the event that there is a hidden terminal and/or an exposed terminal.

[0011] The above summary is provided merely for purposes of summarizing some example embodiments of the invention so as to provide a basic understanding of some aspects of the invention. Accordingly, it will be appreciated that the above described example embodiments are merely examples and should not be construed to narrow the scope or spirit of the invention in any way. It will be appreciated that the scope of the invention encompasses many potential embodiments, some of which will be further described below, in addition to those here summarized. BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0012] Having thus described embodiments of the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

[0013] FIG. 1 illustrates an example of an exposed terminal problem that may be addressed by some example embodiments;

[0014] FIG. 2 illustrates another example problem that may be addressed by some example embodiments;

[0015] FIG. 3 illustrates an example system for facilitating concurrent occupation of a channel in accordance with some example embodiments;

[0016] FIG. 4 illustrates a block diagram of an access point apparatus in accordance with some example embodiments;

[0017] FIG. 5 illustrates a block diagram of a terminal apparatus in accordance with some example embodiments;

[0018] FIG. 6 illustrates an example channel contending mechanism that may be used by some example embodiments;

[0019] FIG. 7 illustrates an example of concurrent channel occupation in the case of an exposed terminal in accordance with some example embodiments;

[0020] FIG. 8 illustrates an example of concurrent channel occupation in the case that a clear to send message is not sent in accordance with some example embodiments;

[0021] FIG. 9 illustrates an example of channel contention and concurrent channel occupation in the case of multiple exposed terminals in accordance with some example embodiments;

[0022] FIG. 10 illustrates a flowchart according to an example method for facilitating concurrent occupation of a channel according to some example embodiments; and

[0023] FIG. 11 illustrates a flowchart according to another example method for facilitating concurrent occupation of a channel according to some example embodiments.

DETAILED DESCRIPTION

[0024] Some embodiments of the present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, various embodiments of the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout.

[0025] As used herein, the terms "data," "content," "information" and similar terms may be used interchangeably to refer to data capable of being transmitted, received, displayed and/or stored in accordance with various example embodiments. Thus, use of any such terms should not be taken to limit the spirit and scope of the disclosure. Further, where a computing device is described herein to receive data from another computing device, it will be appreciated that the data may be received directly from the another computing device or may be received indirectly via one or more intermediary computing devices, such as, for example, one or more servers, relays, routers, network access points, base stations, and/or the like.

[0026] As used in this application, the term 'circuitry' refers to all of the following:

(a)hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) to combinations of circuits and software (and/or firmware), such as (as applicable): (i) to a combination of processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

[0027] This definition of 'circuitry' applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware. The term "circuitry" would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in server, a cellular network device, or other network device.

[0028] FIG. 1 illustrates an example of an exposed terminal problem that may be addressed by some example embodiments. In the example of FIG. 1, there are two D2D communication pairs - a first D2D pair 102 and a second D2D pair 108. The first D2D pair 102 is comprised of the UE1 104 and the UE2 106, and the second D2D pair 108 is comprised of the UE3 1 10 and UE4 112. In the example of FIG. 1, the UE2 106 is an exposed terminal, as the UE2 106 and UE3 110 are within carrier-sensing range of each other. Accordingly, in the example of FIG. 1, the request to send (RTS) message 114 sent by the UE3 110 to the UE4 112 is heard by the UE2 106. However, the UE2 106 is outside of carrier-sensing range of the UE4 112, and does not hear the clear to send (CTS) message 116 sent by the UE4 112 to the UE3 110 in response to the RTS message 114.

[0029] Thus as a result of the RTS message 114, the UE3 110 and UE4 1 12 may occupy the channel and exchange data 118 with each other. However, while the UE2 106 and UE4 112 are outside of carrier-sensing range of each other, as illustrated by the caption 120, the UE2 106 may sense that the channel is busy due to reception of the RTS 114 and may update its Network Allocation Vector (NAV), which may define the duration for which the channel will be occupied, to be the duration of a period indicated in the RTS message 1 14 for which the UE3 1 10 reserved the channel. The UE2 106 may not try to access the channel until its NAV timer reaches 0. Accordingly, while the UE2 106 may safely (e.g., without interference) transmit data to the UE1 104 while the UE3 110 is transmitting data to the UE4 112, and the UE1 104 may safely transmit data to the UE2 106 while the UE4 112 transmits data to the UE3 1 10, the first D2D pair 102 may decline to occupy the channel concurrent with the second D2D pair 108 during the period reserved by the UE3 1 10 because the UE2 106 is exposed to the RTS message 114. Some example embodiments improve channel efficiency in instances such as that in FIG. 1 in which an exposed terminal exists by facilitating concurrent occupation of the channel by both the first D2D pair 102 and the second D2D pair 108.

[0030] FIG. 2 illustrates another example problem that may be addressed by some example embodiments. In the example of FIG. 2, there are two D2D communication pairs - a first D2D pair 202 and a second D2D pair 208. The first D2D pair 202 is comprised of the UE1 204 and the UE2 206, and the second D2D pair 208 is comprised of the UE3 210 and UE4 212. The UE3 210 may send an RTS message 214 to the UE4 212. However, as indicated by caption 220, the UE4 212 may not respond to the RTS message 214 with a CTS message, such as because the channel is busy or the UE4 212 cannot hear the RTS message 214. For example, in the example of FIG. 2, the channel may be occupied prior to the UE3 210 sending the RTS message 214 by communications between the UE4 212 and a wireless local area network (WLAN) station (STA) 216. The WLAN STA 216 may, for example, obtain access to a WLAN from the WLAN access point (AP) 218. Since the UE4 212 does not send a CTS message in the example of FIG. 2, the UE3 210 may back off of contending the channel and may contend the channel again after doubling its contention window 222. However, while the D2D pair 208 does not physically occupy the channel, since the UE2 206 heard the RTS message 214, as indicated by the caption 224, the UE2 206 (and any other UEs that may have heard the RTS message 214) may keep silent for the duration of a NAV period that may correspond to a time indicated in the RTS message 214. Accordingly, the channel may go unused by either the first D2D pair 202 or the second D2D pair 208 during the period indicated as reserved by the RTS message 214. Some example embodiments further described herein may improve channel efficiency in this scenario by facilitating occupancy of the channel by the first D2D pair 202 in the event that the UE2 206 hears the RTS message 214, but no CTS message is sent.

[0031] Referring now to FIG. 3, FIG. 3 illustrates an example system 300 for facilitating concurrent occupation of a channel in accordance with some example embodiments. It will be appreciated that the system 300 as well as the illustrations in other figures are each provided as an example of an embodiment(s) and should not be construed to narrow the scope or spirit of the disclosure in any way. In this regard, the scope of the disclosure encompasses many potential embodiments in addition to those illustrated and described herein. As such, while FIG. 3 illustrates one example of a configuration of a system for facilitating concurrent occupation of a channel, embodiments of the present invention may be implemented in systems having numerous other configurations.

[0032] As illustrated in FIG. 3, an access point 302 may provide cellular network access to one or more terminal apparatuses, such as the UE1 304, UE2 306, UE3 308, UE4 310, UE5 312, and UE6 314. The access point 302 may, for example, comprise an evolved Node B (eNB) that may provide an access point for a Long Term Evolution (LTE) cellular network (e.g., an LTE network, LTE Advanced network, and/or other current or future LTE network). However, it will be appreciated that embodiments of the access point 302 are not so limited. In this regard, it will be appreciated that embodiments disclosed herein are not limited to implementation in the context of LTE networks, but rather may be implemented with any type of cellular network employing one or more mobile access mechanisms, such as LTE, LTE Advanced (LTE-A), Time Division Synchronous Code Division Multiple Access (TD- SCDMA), wideband code division multiple access (W-CDMA), CDMA2000, global system for mobile communications (GSM), general packet radio service (GPRS), and/or the like. The access point 302 may accordingly be embodied as any type of access point that may provide access to a cellular network, such as an eNB, a node B, base station, base transceiver station, and/or the like.

[0033] The terminal apparatuses in the system 300 (e.g., the UE1 304, UE2 306, UE3 308, UE4 310, UES 312, UE6 314, and/or the like) may each comprise any computing device having a cellular network interface that may support interfacing with the access point 302 in order to support cellular network access. By way of non-limiting example, the terminal apparatuses (e.g., the UEl 304, UE2 306, UE3 308, UE4 310, UE5 312, UE6 314, and/or the like) may each respectively be embodied as a mobile communication device, mobile telephone, personal digital assistant (PDA), smart phone, tablet computing device, pager, laptop computer, desktop computer with a cellular network adapter, portable game device, positioning device, some combination thereof, or the like. While the terminal apparatuses of the system 300 (e.g., the UEl 304, UE2 306, UE3 308, UE4 310, UE5 312, and UE6 314) are illustrated in FIG. 3 as comprising user equipment (UE) devices, it will be appreciated that illustrations and discussion referencing a UE(s) are provided by way of example, and not by way of limitation, as where examples are described and/or illustrated to use UEs, any type of terminal apparatus may be substituted for a UE within the scope of the disclosure.

[0034] The terminal apparatuses of the system 300 may be grouped into a plurality of D2D communication groups, which may be served by the access point 302. Each D2D communication group may be comprised of two or more terminal apparatuses. The illustration of FIG. 3 illustrates three such D2D communication groups, including a first D2D pairing including the UEl 304 and UE2 306, a second D2D pairing including the UE3 308 and UE4 310, and a third D2D pairing including the UE5 312 and UE6 314. However, it will be appreciated that the system 300 is not limited to including three D2D pairings, as the system 300 may include additional or fewer D2D communication groups in some

implementations. Further, in some implementations, a D2D communication group may include more than two terminal apparatuses.

[0035] The access point 302 may be configured to support setup of D2D communication between terminal apparatuses in a D2D communication group. In this regard, the access point 302 may be configured to allocate resources (e.g., in-band resources) for D2D communication, coordinate D2D link setup to accommodate D2D communication between two or more terminal apparatuses in a D2D communication group, control D2D data transmission by terminal apparatuses in a D2D communication group, and/or the like. The access point 302 may be configured to provide such control signaling to support setup of D2D communication via cellular control signaling 316 (e.g., via LTE control signaling and/or via control signaling in accordance with some other cellular communication protocol) to the terminal apparatuses of the system 300. The members of a D2D communication group may communicate via a D2D link 318, which may, for example, comprise wireless transmission of data on an unlicensed band, such as a band in the ISM range. Accordingly, in accordance with some example embodiments, the terminal apparatuses in the system 300 (e.g., the UEl 304, UE2 306, UE3 308, UE4 310, UE5 312, UE6 314, and/or the like) may comprise both a first modem supporting a first wireless access technology (e.g., a cellular modem) for supporting cellular network communication with the access point 302 and a second modem supporting a different wireless access technology (e.g., a WLAN modem) for supporting D2D communication on an unlicensed band.

[0036] FIG. 4 illustrates a block diagram of an access point apparatus 402 in accordance with some example embodiments. However, it should be noted that the components, devices or elements illustrated in and described with respect to FIG. 4 below may not be mandatory and thus some may be omitted in certain embodiments. Additionally, some embodiments may include further or different components, devices or elements beyond those illustrated in and described with respect to FIG. 4.

[0037] FIG. 4 illustrates an apparatus that may comprise or be employed on a cellular network access point, such as the access point 302, and which may be configured to perform at least some of the functionality of an access point as described herein. As such, by way of example, the access point apparatus 402 may comprise or be implemented on an eNB, node B, base station, base transceiver station, and/or other cellular network access point. Although illustrated as a single entity, in some example embodiments, the access point apparatus 402 may further comprise one or more supporting cellular network nodes or other entities. As such, it will be appreciated that functionalities attributed to the access point apparatus 402 in accordance with various example embodiments may, in some example embodiments be performed by multiple apparatuses, which may act in concert to provide functionalities attributed to the access point apparatus 402.

[0038] The access point apparatus 402 may include or otherwise be in communication with processing circuitry 410 that is configurable to perform actions in accordance with one or more example embodiments disclosed herein. In this regard, the processing circuitry 410 may be configured to perform and/or control performance of one or more functionalities of the access point apparatus 402 in accordance with various example embodiments, and thus may provide means for performing functionalities of the access point apparatus 402 in accordance with various example embodiments. The processing circuitry 410 may be configured to perform data processing, application execution and/or other processing and management services according to one or more example embodiments. In some

embodiments, the access point apparatus 402 or a portion(s) or component(s) thereof, such as the processing circuitry 410, may be embodied as or comprise a chip or chip set. In other words, the access point apparatus 402 or the processing circuitry 410 may comprise one or more physical packages (e.g., chips) including materials, components and/or wires on a structural assembly (e.g., a baseboard). The structural assembly may provide physical strength, conservation of size, and/or limitation of electrical interaction for component circuitry included thereon. The access point apparatus 402 or the processing circuitry 410 may therefore, in some cases, be configured to implement an embodiment of the invention on a single chip or as a single "system on a chip." As such, in some cases, a chip or chipset may constitute means for performing one or more operations for providing the functionalities described herein.

[0039] In some example embodiments, the processing circuitry 410 may include a processor 412 and, in some embodiments, such as that illustrated in FIG. 4, may further include memory 414. The processing circuitry 410 may be in communication with or otherwise control a communication interface 418 and/or a D2D information broadcast controller 420. The processing circuitry 410 may be embodied as a circuit chip (e.g., an integrated circuit chip) configured (e.g., with hardware, software or a combination of hardware and software) to perform operations described herein. However, in some embodiments, the processing circuitry 410 may be embodied as a portion of a server, computer, workstation or other computing device.

[0040] The processor 412 may be embodied in a number of different ways. For example, the processor 412 may be embodied as various processing means such as one or more of a microprocessor or other processing element, a coprocessor, a controller or various other computing or processing devices including integrated circuits such as, for example, an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), or the like. Although illustrated as a single processor, it will be appreciated that the processor 412 may comprise a plurality of processors. The plurality of processors may be in operative

communication with each other and may be collectively configured to perform one or more functionalities of the access point apparatus 402 as described herein. The plurality of processors may be embodied on a single computing device or distributed across a plurality of computing devices collectively configured to function as the access point apparatus 402. In some example embodiments, the processor 412 may be configured to execute instructions stored in the memory 414 or otherwise accessible to the processor 412. As such, whether configured by hardware or by a combination of hardware and software, the processor 412 may represent an entity (e.g., physically embodied in circuitry - in the form of processing circuitry 410) capable of performing operations according to embodiments of the present invention while configured accordingly. Thus, for example, when the processor 412 is embodied as an ASIC, FPGA or the like, the processor 412 may be specifically configured hardware for conducting the operations described herein. Alternatively, as another example, when the processor 412 is embodied as an executor of software instructions, the instructions may specifically configure the processor 412 to perform one or more operations described herein.

[0041] In some example embodiments, the memory 414 may include one or more non- transitory memory devices such as, for example, volatile and/or non-volatile memory that may be either fixed or removable. In this regard, the memory 414 may comprise a non- transitory computer-readable storage medium. It will be appreciated that while the memory 414 is illustrated as a single memory, the memory 414 may comprise a plurality of memories. The plurality of memories may be embodied on a single computing device or may be distributed across a plurality of computing devices collectively configured to function as the access point apparatus 402. The memory 414 may be configured to store information, data, applications, instructions or the like for enabling the access point apparatus 402 to carry out various functions in accordance with one or more example embodiments. For example, the memory 414 may be configured to buffer input data for processing by the processor 412. Additionally or alternatively, the memory 414 may be configured to store instructions for execution by the processor 412. As yet another alternative, the memory 414 may include one or more databases that may store a variety of files, contents or data sets. Among the contents of the memory 414, applications may be stored for execution by the processor 412 in order to carry out the functionality associated with each respective application. In some cases, the memory 414 may be in communication with one or more of the processor 412,

communication interface 418, or D2D information broadcast controller 420 via a bus(es) for passing information among components of the access point apparatus 402.

[0042] The communication interface 418 may include one or more interface mechanisms for enabling communication with other devices and/or networks. In some example

embodiments, the communication interface 418 may be any means such as a device or circuitry embodied in either hardware, or a combination of hardware and software that is configured to receive and/or transmit data from/to a network and/or any other device or module that may be in communication with the processing circuitry 410. By way of example, the communication interface 418 may be configured to facilitate over-the-air cellular communications between one or more terminal apparatuses (e.g., the UE1 304, UE2 306, UE3 308, UE4 310, UE5 312, UE6 314, terminal apparatus 502 illustrated in FIG. 5, and/or the like) and the access point apparatus 402. By way of further example, the communication interface 418 may be further configured to facilitate communication with a cellular core network such that data may be communicated between a terminal apparatus and one or more other network- connected apparatuses. The communication interface 418 may accordingly include, for example, an antenna (or multiple antennas) and supporting hardware and/or software for enabling communications with a wireless communication network and/or a communication modem or other hardware/software for supporting communication via cable, digital subscriber line (DSL), universal serial bus (USB), Ethernet or other methods.

[0043] In some example embodiments, the processor 412 (or the processing circuitry 410) may be embodied as, include, or otherwise control a D2D information broadcast controller 420. As such, the D2D information broadcast controller 420 may be embodied as various means, such as circuitry, hardware, a computer program product comprising a computer readable medium (for example, the memory 414) storing computer readable program instructions executable by a processing device (for example, the processor 412), or some combination thereof. The D2D information broadcast controller 420 may be capable of communication with one or more of the memory 414 or communication interface 418 to access, receive, and/or send data as may be needed to perform one or more of the

functionalities of the D2D information broadcast controller 420 as described herein.

[0044] FIG. 5 illustrates a block diagram of a terminal apparatus 502 in accordance with some example embodiments. However, it should be noted that the components, devices or elements illustrated in and described with respect to FIG. 5 below may not be mandatory and thus some may be omitted in certain embodiments. Additionally, some embodiments may include further or different components, devices or elements beyond those illustrated in and described with respect to FIG. 5.

[0045] The terminal apparatus 502 may comprise an apparatus that may be implemented on terminal apparatus configured for D2D communication. By way of non-limiting example, the terminal apparatus 502 may be implemented on a mobile communication device, mobile telephone, personal digital assistant (PDA), smart phone, tablet computing device, pager, laptop computer, desktop computer with a cellular network adapter, portable game device, positioning device, some combination thereof, or the like. The terminal apparatus 502 may, for example, be implemented on the UEl 304, UE2 306, UE3 308, UE4 310, UE5 312, UE6 314, and/or the like.

[0046] Referring now to FIG. 5, the terminal apparatus 502 may include or otherwise be in communication with processing circuitry 510 that is configurable to perform actions in accordance with one or more example embodiments disclosed herein. In this regard, the processing circuitry 510 may be configured to perform and/or control performance of one or more functionalities of the terminal apparatus 502 in accordance with various example embodiments, and thus may provide means for performing functionalities of the terminal apparatus 502 in accordance with various example embodiments. The processing circuitry 510 may be configured to perform data processing, application execution and/or other processing and management services according to one or more example embodiments. In some embodiments, the terminal apparatus 502 or a portion(s) or component(s) thereof, such as the processing circuitry 510, may be embodied as or comprise a chip or chip set. In other words, the terminal apparatus 502 or the processing circuitry 510 may comprise one or more physical packages (e.g., chips) including materials, components and/or wires on a structural assembly (e.g., a baseboard). The structural assembly may provide physical strength, conservation of size, and/or limitation of electrical interaction for component circuitry included thereon. The terminal apparatus 502 or the processing circuitry 510 may therefore, in some cases, be configured to implement an embodiment of the invention on a single chip or as a single "system on a chip." As such, in some cases, a chip or chipset may constitute means for performing one or more operations for providing the functionalities described herein.

[0047] In some example embodiments, the processing circuitry 510 may include a processor 512 and, in some embodiments, such as that illustrated in FIG. 5, may further include memory 514. The processing circuitry 510 may be in communication with or otherwise control a user interface 516, a communication interface 518, and/or a channel contention controller 520. As such, the processing circuitry 510 may be embodied as a circuit chip (e.g., an integrated circuit chip) configured (e.g., with hardware, software or a combination of hardware and software) to perform operations described herein.

[0048] The processor 512 may be embodied in a number of different ways. For example, the processor 512 may be embodied as various processing means such as one or more of a microprocessor or other processing element, a coprocessor, a controller or various other computing or processing devices including integrated circuits such as, for example, an ASIC (application specific integrated circuit), an FPGA (field programmable gate array), or the like. Although illustrated as a single processor, it will be appreciated that the processor 512 may comprise a plurality of processors. The plurality of processors may be in operative

communication with each other and may be collectively configured to perform one or more functionalities of the terminal apparatus 502 as described herein. The plurality of processors may be embodied on a single computing device or distributed across a plurality of computing devices collectively configured to function as the terminal apparatus 502. In some example embodiments, the processor 512 may be configured to execute instructions stored in the memory 514 or otherwise accessible to the processor 512. As such, whether configured by hardware or by a combination of hardware and software, the processor 512 may represent an entity (e.g., physically embodied in circuitry - in the form of processing circuitry 510) capable of performing operations according to embodiments of the present invention while configured accordingly. Thus, for example, when the processor 512 is embodied as an ASIC, FPGA or the like, the processor 512 may be specifically configured hardware for conducting the operations described herein. Alternatively, as another example, when the processor 512 is embodied as an executor of software instructions, the instructions may specifically configure the processor 512 to perform one or more operations described herein.

[0049] In some example embodiments, the memory 514 may include one or more non- transitory memory devices such as, for example, volatile and/or non- volatile memory that may be either fixed or removable. In this regard, the memory 514 may comprise a non- transitory computer-readable storage medium. It will be appreciated that while the memory 514 is illustrated as a single memory, the memory 514 may comprise a plurality of memories. The plurality of memories may be embodied on a single computing device or may be distributed across a plurality of computing devices collectively configured to function as the terminal apparatus 502. The memory 514 may be configured to store information, data, applications, instructions or the like for enabling the terminal apparatus 502 to carry out various functions in accordance with one or more example embodiments. For example, the memory 514 may be configured to buffer input data for processing by the processor 512. Additionally or alternatively, the memory 514 may be configured to store instructions for execution by the processor 512. As yet another alternative, the memory 514 may include one or more databases that may store a variety of files, contents or data sets. Among the contents of the memory 514, applications may be stored for execution by the processor 512 in order to carry out the functionality associated with each respective application. In some cases, the memory 514 may be in communication with one or more of the processor 512, user interface 516, communication interface 518, or channel contention controller 520 via a bus(es) for passing information among components of the terminal apparatus 502.

[0050] The user interface 516 (if implemented) may be in communication with the processing circuitry 510 to receive an indication of a user input at the user interface 516 and/or to provide an audible, visual, mechanical or other output to the user. As such, the user interface 516 may include, for example, a keyboard, a mouse, a joystick, a display, a touch screen, a microphone, a speaker, and/or other input/output mechanisms.

[0051] The communication interface 518 may include one or more interface mechanisms for enabling communication with other devices and/or networks. In some cases, the communication interface 518 may be any means such as a device or circuitry embodied in either hardware, or a combination of hardware and software that is configured to receive and/or transmit data from/to a network and/or any other device or module in communication with the processing circuitry 510. By way of example, the communication interface 518 may be configured to provide a cellular network interface (e.g., a cellular modem) to enable the terminal apparatus 502 to interface with a cellular network, such as via an access point 302, access point apparatus 402, and/or the like. As another example, the communication interface 518 may be configured to provide a wireless network interface (e.g., a WLAN modem and/or the like) to enable the terminal apparatus 502 to engage in D2D

communication with another terminal apparatus, such as over an unlicensed band. The communication interface 518 may include, for example, an antenna (or multiple antennas) and supporting hardware and/or software for enabling communications with a wireless communication network (e.g., a cellular network, WSN, and/or the like) and/or a

communication modem or other hardware/software for supporting communication via cable, digital subscriber line (DSL), universal serial bus (USB), Ethernet or other methods.

[0052] In some example embodiments, the processor 512 (or the processing circuitry 510) may be embodied as, include, or otherwise control a channel contention controller 520. As such, the channel contention controller 520 may be embodied as various means, such as circuitry, hardware, a computer program product comprising computer readable program instructions stored on a computer readable medium (for example, the memory 514) and executed by a processing device (for example, the processor 512), or some combination thereof. The channel contention controller 520 may be capable of communication with one or more of the memory 514, user interface 516, or communication interface 518 to access, receive, and/or send data as may be needed to perform one or more of the functionalities of the channel contention controller 520 as described herein.

[0053] In some example embodiments, the D2D information broadcast controller 420 may be configured to cause the access point apparatus 402 to send D2D configuration and control information to one or more terminal apparatuses (e.g., terminal apparatuses 502) that may be served by the access point apparatus 402. By way of non-limiting example, this D2D configuration and control information may be broadcast to terminal apparatuses that may be within a coverage area of the access point apparatus 402 and/or may be unicast to one or more individual terminal apparatuses that may be served by the access point apparatus 402.

[0054] In some example embodiments, the D2D information broadcast controller 420 may be configured to cause the access point apparatus 402 to broadcast D2D status information related to a status of one or more D2D communication groups within a coverage area of the access point apparatus 402. The D2D status information may, for example, include an identification (ID) one or more terminal apparatuses in a D2D communication group, a media access control (MAC) address of one or more terminal apparatuses in a D2D communication group, transmission-reception (Tx-Rx) timeslot assignment information for a D2D communication group, and/or the like. The D2D information broadcast controller 420 may, for example, be configured to cause the access point apparatus 402 to broadcast such status information periodically, responsive to formation of a new D2D communication group, responsive to updating a configuration (e.g., Tx-Rx timeslot assignment) for a D2D communication group, and/or the like. In embodiments wherein the D2D status information is broadcast, terminal apparatuses within the coverage area of the access point apparatus 402 may hear the status information. Accordingly, a terminal apparatus 502 that may be within the coverage area of the access point apparatus 402 may be configured to obtain D2D status information that may be broadcast by the access point apparatus 402, such as via a cellular modem that may be implemented on the terminal apparatus 502 in some example

embodiments.

[0055] In some example embodiments, terminal apparatuses 502 that want to contend for a channel that may be used for D2D communication among members of a D2D

communication group may use a channel contention mechanism. In this regard, FIG. 6 illustrates an example channel contending mechanism that may be used by terminal apparatuses 502 in accordance with some example embodiments. More particularly, FIG. 6 illustrates an example implementation of a Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism that may be used by terminal apparatuses contending a channel for collision avoidance in accordance with some example embodiments. It will be appreciated, however, that in some example embodiments, a contention mechanism other than CSMA/CA may be used in addition to or in lieu of CSMA/CA. In the example of FIG. 6, UEl 602 and UE2 604 may comprise LTE user equipment devices, which may comprise a D2D pairing. The UEl 602 and UE2 604 may each comprise embodiments of a terminal apparatus 502. There may additionally be one or more other terminals 606, which may include LTE UEs, WLAN STAs, and/or the like. The UEl 602 may desire to contend a channel, and may send a message requesting to send data on the channel, such as the RTS (Request to Send) message 608, to the UE2 604. The RTS message 608 may, for example, be sent using WLAN network technology via a WLAN modem. A terminal other than the UE2 604 that hears the RTS message 608 may start a NAV period 620 beginning from a time 610 at which the RTS message 608 was received by the other terminal, and extending for a period indicated in the RTS message 608 during which the channel may be reserved by the UEl 602, which may terminate at the time 612, after which a new round of channel contention may begin. The UE2 604 may receive the RTS message 608 and, following a Short Interframe Space (SIFS) period, may send a clear to send (CTS) message to the UEl 602 in response to the RTS message 608. The CTS message 614 may, for example, be sent using WLAN network technology via a WLAN modem. A terminal other than the UEl 602 that hears the CTS message 614 may set the NAV period 622, which may expire at time 612.

[0056] The UEl 602 may receive the CTS message 614, and, in response to the CTS message 614, the UEl 602 and UE2 604 may occupy the unlicensed channel for the period during which the channel is reserved by the UEl 602 (e.g., until time 612). In this regard, the UEl 602 and UE2 604 may engage in D2D communication over the unlicensed channel in accordance with a cellular networking protocol (e.g. LTE protocol) via cellular modems (e.g., LTE modems) that may be implemented on the UEl 602 and UE2 604. The UEl 602 and UE2 604 may engage in D2D communication in alternating Tx-Rx time slots 618. In embodiments implemented in LTE systems, the Tx-Rx time slots may be 1 millisecond (ms) in length. However, it will be appreciated that the length of the Tx-Rx time slots may vary in embodiments implemented in non-LTE systems. The Tx-Rx time slots may, for example, be assigned by an access point apparatus 402 that may serve the UEl 602 and UE2 604. As will be described further herein below, some example embodiments enable a terminal 606 that hears the RTS message 608, but not the CTS message 614 to engage in a secondary contention of the channel and occupy the channel concurrently with the UEl 602 and UE2 604.

[0057] In some example embodiments, the channel contention controller 520 associated with a terminal apparatus 502 that is a member of a first D2D communication group may be configured to detect (e.g., receive) a message requesting send data on a channel (e.g., an RTS message) sent by a second terminal that is a member of a second D2D communication group. The RTS message may, for example, be heard by a WLAN modem of the terminal apparatus 502. The first and second D2D communication groups may be served by the same access point apparatus 402. In the event that the terminal apparatus 502 does not receive a CTS message sent in response to the RTS message (e.g., a CTS message that may be sent by a terminal that is paired with the second terminal in the second D2D communication group) within a predefined period of time following the channel contention controller 520 hearing the RTS message, the channel contention controller 520 may be configured to determine that the terminal apparatus 502 has not heard a CTS message within the predefined period of time following the terminal apparatus 502 hearing the RTS message. The predefined period of time may, for example, comprise a SIFS period following receipt of the RTS message, during which the channel contention controller 520 may be configured to listen for a CTS message.

[0058] In some example embodiments, the channel contention controller 520 may be configured to recognize a situation in which the terminal apparatus 502 hears an RTS message, but does not hear a CTS message as a secondary contention requirement indicator. The channel contention controller 520 may be configured in response to the secondary contention requirement indicator to format a message to another terminal that is paired with the terminal apparatus 502 in the first D2D communication group (e.g., a D2D partner of the terminal apparatus 502) requesting that the D2D partner send data to the terminal apparatus 502 over the channel during the period of time during which the channel is reserved by the terminal that sent the RTS message, which may be indicated in the RTS message. This message may be referred to as a D2D shared band data request (DSBDR) message. The DSBDR message may include an indication of an identifier of the apparatus 502, such as a UE ID, so as to identify the sender of the DSBDR message to any terminals that receive the DSBDR message. IN some example embodiments, the DSBDR message may include an indicator indicating that the signaling frame is a DSBDR signaling. The channel contention controller 520 may be configured to cause the terminal apparatus 502 to send the DSBDR message to the D2D partner of the terminal apparatus 502, The DSBDR message may be sent over the channel by a cellular modem of the terminal apparatus 502 in accordance with a cellular signaling protocol, such as LTE protocol.

[0059] In some example embodiments, the channel contention controller 520 may be configured to cause the terminal apparatus 502 to send the DSBDR message in a random interval of a subframe on the channel. The D2D partner of the terminal apparatus 502 may accordingly listen to the channel during the subframe and detect any DSBDR messages that may be sent by terminals within range during the subframe. Sending the DSBDR message in a random interval of the subframe may, for example, reduce the possibility of collision in the event that multiple terminals hear the RTS message, but not a CTS message, and decide to send DSBDR messages prompting their D2D partners to send data on the channel. [0060] In embodiments wherein the DSBDR message is sent during a random interval, the channel contention controller 520 may be configured to determine the random interval. By way of example, in some such example embodiments, the channel contention controller 520 may be configured to determine the random interval by dividing a period of the subframe (e.g., 1 ms for embodiments implemented in LTE systems) by an amount of time that may be required for the terminal apparatus 502 to send the DSBDR message. The resulting quotient may be floored to derive an integer, N. The channel contention controller 520 may be configured to generate a random integer, , that is uniformly distributed from 0 to N. The channel contention controller 520 may determine the random interval of the subframe to be the i'^h time interval of the subframe.

[0061] In the event that a D2D partner of the terminal apparatus 502 sends data over the channel to the terminal apparatus 502, the first D2D communication group may occupy the channel during at least a portion of the period of time during which the channel is reserved by the second terminal (e.g., the period of time indicated in the RTS message sent by the second terminal). Accordingly, the first D2D communication group may occupy the channel concurrently with the primary channel occupier (e.g., the second D2D communication group), thus providing for improved channel efficiency and capacity.

[0062] The channel contention controller 520 may be configured to coordinate

transmissions on the channel by the first D2D communication group to avoid interfering with any communications that may be sent over the channel by the second D2D communication group. In embodiments in which an access point apparatus 402 serving the first and second D2D communication groups is configured to broadcast D2D status information including Tx- Rx timeslot assignment information for the D2D communication groups, the channel contention controller 520 may be configured to use the Tx-Rx timeslot assignment

information to coordinate transmissions on the channel to avoid interfering with any communications that may be sent on the channel by the second D2D communication group. In this regard, the channel contention controller 520 may know the schedule for the assigned Tx and Rx timeslots of the second terminal based on Tx-Rx timeslot assignment information that may be broadcast by the access point apparatus 402. The channel contention controller 520 may use this knowledge to coordinate transmissions such that the terminal apparatus 502 transmits data to its D2D partner only during the second terminal's Tx timeslot and listens for data that may be sent by the D2D partner during the second terminal's Rx timeslot.

Accordingly, the terminal apparatus 502 may avoid transmitting data over the channel during the second terminal's Rx timeslot to avoid interfering with transmissions between members of the second D2D communication group, which is the primary channel occupier.

[0063] A channel contention controller 520 that may be associated with a terminal receiving a DSBDR message from its D2D partner may be configured whether to send data over the channel to its D2D partner in response to the DSBDR message. If the channel contention controller 520 only detects DSBDR signaling from its D2D partner during a subframe, the channel contention controller 520 may cause the terminal to send data to its partner over the channel during the next subframe.

[0064] If the channel contention controller 520 detects multiple DSBDR messages, such as in the case that the terminal receives DSBDR messages from its D2D partner and from one or more further terminals, the channel contention controller 520 may be configured to compare a priority that may be associated with each of the received DSBDR messages. If the channel contention controller 520 determines that the DSBDR message sent by the terminal's D2D partner is associated with the highest priority among the received DSBDR messages (e.g., the DSBDR messages received during the subframe), the channel contention controller 520 may cause the terminal to start transmitting data to its D2D partner during the next subframe. If, however, the DSBDR message sent by the terminal's D2D partner is not associated with the highest priority among the received DSBDR messages, the channel contention controller 520 may decline to respond to the DSBDR message sent by its D2D partner.

[0065] The priority associated with a DSBDR message may correspond to a predefined priority that may be associated with a terminal that sent the DSBDR message. The priority may, for example, be predefined by the access point apparatus 402. For example, the priority of a terminal may correspond to an identifier for the terminal. As an example, the terminal having the smallest UE ID may have the highest priority.

[0066] If the channel contention controller 520 detects a DSBDR message sent by its D2D partner and also senses energy from another source on the channel, the channel contention controller 520 may decline to respond to the DSBDR message sent by its D2D partner. If a DSBDR message is not even heard by the sending terminal's D2D partner, the D2D partner may not respond to the DSBDR message.

[0067] FIG. 7 illustrates an example of concurrent channel occupation in the case of an exposed terminal in accordance with some example embodiments. In this regard, FIG. 7 illustrates application of some example embodiments to the exposed terminal scenario illustrated in FIG. 1. In the example of FIG. 7, there are two D2D communication groups - a first D2D pair 702 and a second D2D pair 708, which may be served by the same cellular network access point. The first D2D pair 702 is comprised of the UEl 704 and the UE2 706, and the second D2D pair 708 is comprised of the UE3 710 and UE4 712. The UEl 704, UE2 706, UE3 710, and UE4 712 may each comprise embodiments of a terminal apparatus 502.

[0068] The cellular network access point serving the first D2D pair 702 and second D2D pair 708 may broadcast status information for the D2D pairs periodically in its coverage area. The status information may, for example, include UE ID information, MAC address information, D2D pair Tx-Rx timeslot assignment information, and/or the like. Accordingly, the D2D pair 702 may know the status information for the second D2D pair 708, and vice versa.

[0069] In the example of FIG. 7, the UE3 710 may successfully access the channel according to a contention mechanism, such as a CSMA/CA mechanism, and may send an RTS frame 714 to the UE4 712. The UE4 712 may respond with a CTS message 716, and the D2D pair 708 may occupy the channel and exchange data 718 for a period 720 indicated by the RTS message 714.

[0070] In the example of FIG. 7, the UE2 706 is an exposed terminal, as the UE2 706 and UE3 710 are within carrier-sensing range of each other. Accordingly, the RTS message 714 sent by the UE3 710 to the UE4 712 may be heard by the UE2 706. However, the UE2 706 is outside of carrier-sensing range of the UE4 712, and does not hear the CTS message 716 sent by the UE4 712 to the UE3 710 in response to the RTS message 114.

[0071] The UE2 706 may also wish to contend the channel, but may have lost to the UE3 710 during the channel contention process. The UE2 706 may sense that the channel is busy and determine that it has not heard a CTS message within a predefined period of time (e.g., a SIFS period) subsequent to hearing the RTS message 714. Responsive to this determination, UE2 706 may trigger a secondary channel contention, and may send a DSBDR message 722 to the UEl 704 over the channel. The DSBDR message 722 may be sent during a random time interval in the subframe (e.g., a 1 ms LTE subframe).

[0072] In the example of FIG. 7, the UEl 704 may only detect the DSBDR message 722 during the subframe, as indicated by the caption 724. The UEl 704 may accordingly respond to the DSBDR message 722 by transmitting data 726 to the UE2 706 over the channel. The D2D pair 702 may accordingly occupy the channel concurrent with the D2D pair 708 for at least a portion of the period 720 during which the channel is reserved by the UE3 710 in accordance with the time indicated in the RTS message 714. [0073] The UE1 704 and UE2 706 may use D2D pair status information (e.g., Tx-RX timeslot assignment information) broadcast by the cellular network access point serving the D2D pair 702 and D2D pair 708 to align the Tx-Rx timeslot of the D2D pair 702 with the Tx- Rx timeslot of the D2D pair 708 so that transmissions on the channel by the D2D pairs do not interfere with each other even though the pairs concurrently occupy the channel. When the duration of the period 720 expires, a new round of channel contention (e.g., CSMA/CA) 728 may begin.

[0074] FIG. 8 illustrates an example of concurrent channel occupation in the case that a clear to send message is not sent in accordance with some example embodiments. In this regard, FIG. 8 illustrates application of some example embodiments to the scenario illustrated in FIG. 2 in which a CTS message is not sent. In the example of FIG. 8, there are two D2D communication groups - a first D2D pair 802 and a second D2D pair 808, which may be served by the same cellular network access point. The first D2D pair 802 is comprised of the UE1 804 and the UE2 806, and the second D2D pair 808 is comprised of the UE3 810 and UE4 812. The UE1 804, UE2 806, UE3 810, and UE4 812 may each comprise embodiments of a terminal apparatus 502.

[0075] The cellular network access point serving the first D2D pair 802 and second D2D pair 808 may broadcast status information for the D2D pairs periodically in its coverage area. The status information may, for example, include UE ID information, MAC address information, D2D pair Tx-Rx timeslot assignment information, and/or the like. Accordingly, the D2D pair 802 may know the status information for the second D2D pair 808, and vice versa.

[0076] In the example of FIG. 8, the UE3 810 may successfully access the channel according to a contention mechanism, such as a CSMA/CA mechanism, and may send an RTS frame 814 to the UE4 812. However, as indicated by caption 820, the UE4 812 may not respond to the RTS message 814 with a CTS message, such as because the channel is busy or because the UE4 812 cannot hear the RTS message 814. For example, in the example of FIG. 8, the channel may be occupied prior to the UE3 810 sending the RTS message 814 by communications between the UE4 812 and a WLAN STA 816. The WLAN STA 816 may, for example, obtain access to a WLAN from the WLAN AP 818.

[0077] In the example of FIG. 8, the UE2 806 and UE3 810 are within carrier-sensing range of each other. Accordingly, the RTS message 814 sent by the UE3 810 to the UE4 812 may be heard by the UE2 806. However, as the UE4 812 does not send a CTS message, the UE2 806 does not hear a CTS message in response to the RTS message, regardless of whether the UE2 806 is within carrier sensing range of the UE4 812.

[0078] The UE2 806 may also wish to contend the channel, but may have lost to the UE3 810 during the channel contention process. The UE2 806 may sense that the channel is busy and determine that it has not heard a CTS message within a predefined period of time (e.g., a SIFS period) subsequent to hearing the RTS message 814. Responsive to this determination, UE2 806 may trigger a secondary channel contention, and may send a DSBDR message 822 to the UEl 804 over the channel. The DSBDR message 822 may be sent during a random time interval in the subframe (e.g., a 1 ms LTE subfirame).

[0079] In the example of FIG. 8, the UEl 804 may only detect the DSBDR message 822 during the subframe, as indicated by the caption 824. The UEl 804 may accordingly respond to the DSBDR message 822 by transmitting data 826 to the UE2 806 over the channel. The D2D pair 802 may occupy the channel for at least a portion of the period 828 during which the channel is reserved by the UE3 810 in accordance with the time indicated in the RTS message 814.

[0080] Since in the example of FIG. 8, the UE4 812 does not respond to the RTS message 814 with a CTS message, the D2D pair 808 does not transmit data on the channel and there is no interference caused by the D2D pair 802 occupying the channel. However, in some example embodiments the UE2 806 may not be able to determine whether it is an exposed terminal and did not hear the CTS (e.g., the example of FIG. 7) or if the CTS was never sent (e.g., the example illustrated in FIG. 8). the UEl 804 and UE2 806 may accordingly use D2D pair status information (e.g., Tx-RX timeslot assignment information) broadcast by the cellular network access point serving the D2D pair 802 and D2D pair 808 to align the Tx-Rx timeslot of the D2D pair 802 with the Tx-Rx timeslot of the D2D pair 808 so that

transmissions by the D2D pair 808 do not interfere with data that may be potentially sent on the channel by the D2D pair 808. When the duration of the period 828 expires, a new round of channel contention (e.g., CSMA/CA) 830 may begin.

[0081] FIG. 9 illustrates an example of channel contention and concurrent channel occupation in the case of multiple exposed terminals in accordance with some example embodiments. In the example of FIG. 9, a first D2D pair is comprised of the UEl 902 and the UE2 904, a second D2D pair is comprised of the UE3 906 and UE4 908, and a third D2D pair comprised of the UE5 910 and UE6 912. All three D2D pairs may be served by the same cellular network access point. The UEl 902, UE2 904, UE3 906, UE4 908, UE5 910, and UE6 912 may each comprise embodiments of a terminal apparatus 502. [0082] The cellular network access point serving the D2D pairs illustrated in FIG. 9 may broadcast status information for the D2D pairs periodically in its coverage area. The status information may, for example, include UE ID information, MAC address information, D2D pair Tx-Rx timeslot assignment information, and/or the like. Accordingly, the D2D pairs may know the status information for other D2D pairs in the coverage area of the cellular network access point.

[0083] In the example of FIG. 9, the UE3 902 may successfully access the channel according to a contention mechanism, such as a CSMA/CA mechanism, and may send an RTS frame 914 to the UE4 904. The RTS message 914 may be sent using a WLAN modem that may be implemented on the UE3 902, The UE4 904 may receive the RTS message 914 via a WLAN modem that may be implemented on the UE4 904. The UE4 904 may respond with a CTS message 916, which may be sent via a WLAN modem that may be implemented on the UE4 904. In response to the CTS message 916, the D2D pair comprised of the UE3 902 and UE4 904may occupy the channel and exchange data for a period 720 that may be indicated by the RTS message 914, which may terminate at time 918. After time 918, new round of channel contention (e.g., CSMA/CA) may begin.

[0084] In the example of FIG. 9, the UE1 906 and UE5 910 may comprise exposed terminals, as the UE1 906 and UE5 910 are within carrier-sensing range of the UE3 902. Accordingly, the RTS message 914 may be heard by the UE1 906 and UE5 910, such as by WLAN modems that may be implemented on the UE1 906 and/or UE5 910. However, the UE1 906 and UE5 910 may be outside of carrier-sensing range of the UE4 904, and do not hear the CTS message 916.

[0085] The UE1 906 and UE5 910 may also wish to contend the channel, but may have lost to the UE3 902 during the channel contention process. As illustrated by 920, the UE1 906 may sense that the channel is busy and determine that it has not heard a CTS message within a predefined period of time (e.g., a SIFS period) subsequent to hearing the RTS message 914. Responsive to this determination, UE1 906 may trigger a secondary channel contention, and may send a DSBDR message 922 to the UE2 908 over the channel (e.g., using a cellular modem, such as an LTE modem). The DSBDR message 922 may be sent during a random time interval in the subframe (e.g., a l ms LTE subframe). Further, as illustrated by 924, the UE5 910 may sense that the channel is busy and determine that it has not heard a CTS message within a predefined period of time (e.g., a SIFS period) subsequent to hearing the RTS message 914. Responsive to this determination, UE5 910 may trigger a secondary channel contention, and may send a DSBDR message 926 to the UE6 912 over the channel (e.g., using a cellular modem, such as an LTE modem). The DSBDR message 926 may be sent during a random time interval in the sub frame (e.g., a l ms LTE subframe).

[0086] The UE2 908 may listen to the channel during the subframe to detect any DSBDR messages that may be sent. As illustrated by operation 928, in the example of FIG. 9, the UE2 908 may receive both the DSBDR message 922 and the DSBDR message 926 in the subframe. Since a further DSBDR message (the DSBDR message 926) was received during the subframe in addition to the DSBDR message 922 from the D2D partner of the UE2 908, the UE2 908 may determine which of the received DSBDR messages is associated with the highest priority. In the example illustrated in FIG. 1, the UE1 906 has a higher priority than the UE5 910. Accordingly, the UE2 908 may determine to respond to the DSBDR message 922 by sending data 930 to the UE1 906 over the channel in the next subframe. The D2D pair comprised of the UE1 906 and UE2 908 may occupy the channel concurrent with the D2D pair comprised of the UE3 902 and UE4 904 for at least a portion of the period during which the channel is reserved by the UE3 710 in accordance with the time indicated in the RTS message 914 (e.g. up till the time 920). The UE1 906 and UE2 908 may use D2D pair status information (e.g., Tx-RX timeslot assignment information) broadcast by the serving cellular network access point to align their Tx-Rx timeslots with the Tx-Rx timeslot of the D2D pair comprised of the UE3 902 and UE4 904 so that transmissions on the channel by the D2D pairs do not interfere with each other even though the pairs concurrently occupy the channel.

[0087] The UE6 912 may also listen to the channel during the subframe to detect any DSBDR messages that may be sent. As illustrated by operation 932, in the example of FIG. 9, the UE6 912 may receive both the DSBDR message 922 and the DSBDR message 926 in the subframe. Since a further DSBDR message (the DSBDR message 922) was received during the subframe in addition to the DSBDR message 926 from the D2D partner of the UE6 912, the UE6 912 may determine which of the received DSBDR messages is associated with the highest priority. In the example illustrated in FIG. 1 , the UE1 906 has a higher priority than the UE5 910. Accordingly, the UE6 912 may determine to not respond to the DSBDR message 926.

[0088] While in the example of FIG. 9, a CTS message 916 is sent by the UE4 904, but not heard by the UE1 906 and UE5 910, it will be appreciated that secondary channel contention may be proceed in a manner substantially similar to that illustrated in FIG. 9 in an alternative scenario in which the UE4 904 does not send a CTS message 916 in response to the RTS message 914. In this regard, both the UE1 906 and the UE5 910 may opt to trigger a secondary channel contention responsive to not hearing a CTS message within a predefined period of time after hearing the RTS message 914.

[0089] FIG. 10 illustrates a flowchart according to an example method for facilitating concurrent occupation of a channel according to some example embodiments. In this regard, FIG. 10 illustrates operations that may be performed at a terminal apparatus 502. The operations illustrated in and described with respect to FIG. 10 may, for example, be performed by, with the assistance of, and/or under the control of one or more of the processing circuitry 510, processor 512, memory 514, communication interface 518, or channel contention controller 520. Operation 1000 may comprise determining, at a first terminal that is a member of a first device-to-device (D2D) communication group, that the first terminal has not heard a clear to send message within a predefined period of time following the first terminal hearing a message requesting to send data on a channel sent by a second terminal that is a member of a second D2D communication group. The processing circuitry 510, processor 512, memory 514, communication interface 518, and/or channel contention controller 520 may, for example, provide means for performing operation 1000. Operation 1010 may comprise determining, responsive to the determination of operation 1000, to format and send a DSBDR message to a third terminal requesting the third terminal to send data to the first terminal over the channel during a period of time during which the channel is reserved by the second terminal. The third terminal may be a member of the first D2D communication group. The processing circuitry 510, processor 512, memory 514, communication interface 518, and/or channel contention controller 520 may, for example, provide means for performing operation 1010.

[0090] In an instance in which the third terminal receives the DSBDR message sent by the first terminal and decides to respond, the method may further comprise operation 1020, which may comprise receiving, at the first terminal, data sent by the third terminal over the channel in response to the DSBDR message. The processing circuitry 510, processor 512, memory 514, communication interface 518, and/or channel contention controller 520 may, for example, provide means for performing operation 1020. In an instance in which the third terminal sends data to the first terminal responsive to the DSBDR message, the method may further comprise operation 1030, which may comprise occupying the channel during at least a portion of the period of time during which the channel is reserved by the second terminal. The period of time during which the channel is reserved by the second terminal may, for example, be indicated in the message sent by the second terminal requesting to send data on the channel. In some example embodiments, operation 1030 may further comprise using Tx- Rx timeslot assignment information for the second D2D communication group that may be broadcast by a serving cellular network access point to coordinate transmissions on the channel by the first D2D communication group to avoid interfering with any communications that may be sent over the channel by the second D2D communication group. The processing circuitry 510, processor 512, memory 514, communication interface 518, and/or channel contention controller 520 may, for example, provide means for performing operation 1030.

[0091] FIG. 11 illustrates a flowchart according to another example method for facilitating concurrent occupation of a channel according to some example embodiments. In this regard, FIG. 1 1 illustrates operations that may be performed at a terminal apparatus 502. The operations illustrated in and described with respect to FIG. 10 may, for example, be performed by, with the assistance of, and/or under the control of one or more of the processing circuitry 510, processor 512, memory 514, communication interface 518, or channel contention controller 520. Operation 1100 may comprise receiving, at a first terminal, a DSBDR message sent by a second terminal that is a D2D partner of the first terminal in a D2D communication group. The processing circuitry 510, processor 512, memory 514, communication interface 518, and/or channel contention controller 520 may, for example, provide means for performing operation 1100.

[0092] Operation 1110 may comprise determining, at the first terminal, whether to respond to the DSBDR message sent by the second terminal. In an instance in which the first terminal only detects DSBDR signaling from the second terminal during a subframe, operation 1110 may comprise the first terminal determining to respond to the DSBDR message by sending data to the second terminal over the channel during the next subframe.

[0093] Alternatively, if the first terminal detects multiple DSBDR messages, such as in the case that the terminal receives DSBDR messages from the second terminal and from one or more further terminals, operation 1110 may comprise the first terminal comparing a priority that may be associated with each of the received DSBDR messages and determining which of the received DSBDR messages is associated with the highest priority. If the first terminal determines that the DSBDR message sent by the second terminal is associated with the highest priority among the received DSBDR messages, the first terminal may determine to respond to the DSBDR message by sending data to the second terminal over the channel during the next subframe. If, however, the DSBDR message sent by the second terminal is not associated with the highest priority among the received DSBDR messages, the first terminal may decline to respond to the DSBDR message sent by the second terminal. [0094] As still a further alternative, if the first terminal senses energy from another source on the channel in addition to receiving the DSBDR message from the second terminal, the operation 1 1 10 may comprise the first terminal determining to decline to respond to the DSBDR message sent by the first terminal. The processing circuitry 510, processor 512, memory 514, communication interface 518, and/or channel contention controller 520 may, for example, provide means for performing operation 1110.

[0095] FIGS. 10-1 1 are flowcharts of a system, method and program product according to example embodiments of the invention. It will be understood that each block of the flowcharts, and combinations of blocks in the flowcharts, may be implemented by various means, such as hardware, firmware, processor, circuitry and/or other device associated with execution of software including one or more computer program instructions. For example, one or more of the procedures described above may be embodied by computer program instructions. In this regard, the computer program instructions which embody the procedures described above may be stored by a memory device of an apparatus employing an

embodiment of the present invention and executed by a processor in the apparatus. As will be appreciated, any such computer program instructions may be loaded onto a computer or other programmable apparatus (e.g., hardware) to produce a machine, such that the resulting computer or other programmable apparatus provides for implementation of the functions specified in the flowcharts block(s). These computer program instructions may also be stored in a non-transitory computer-readable storage memory that may direct a computer or other programmable apparatus to function in a particular manner, such that the instructions stored in the computer-readable storage memory produce an article of manufacture the execution of which implements the function specified in the flowcharts block(s). The computer program instructions may also be loaded onto a computer or other programmable apparatus to cause a series of operations to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide operations for implementing the functions specified in the flowcharts block(s).

[0096] Accordingly, blocks of the flowcharts support combinations of means for perfom ing the specified functions and combinations of operations for performing the specified functions. It will also be understood that one or more blocks of the flowcharts, and combinations of blocks in the flowcharts, can be implemented by special purpose hardware- based computer systems which perform the specified functions, or combinations of special purpose hardware and computer instructions. [0097] Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although the foregoing descriptions and the associated drawings describe example embodiments in the context of certain example combinations of elements and/or functions, it should be appreciated that different

combinations of elements and/or functions may be provided by alternative embodiments without departing from the scope of the appended claims. In this regard, for example, different combinations of elements and/or functions than those explicitly described above are also contemplated as may be set forth in some of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

What is Claimed is:

1. A method comprising:

determining, at a first terminal that is a member of a first device-to-device (D2D) communication group, that the first terminal has not heard a clear to send message within a predefined period of time following the first terminal hearing a message requesting to send data on a channel sent by a second terminal that is a member of a second D2D

communication group; and

determining, responsive to determining that the first terminal has not heard a clear to send message within the predefined period of time following the first terminal hearing the message requesting to send data on the channel, to format and send a D2D shared band data request (DSBDR) message to a third terminal requesting the third terminal to send data to the first terminal over the channel during a period of time during which the channel is reserved by the second terminal, wherein the third terminal is a member of the first D2D

communication group.

2. The method of Claim 1 , wherein the predefined period of time following the first terminal hearing the message requesting to send data on the channel comprises a Short Interframe Space(SIFS) period.

3. The method of any of Claims 1-2, further comprising:

determining a random interval of a subframe on the channel; and

causing the DSBDR message to be sent from the first terminal to the third terminal over the channel in the determined random interval of the subframe.

4. The method of Claim 3, wherein determining the random interval of the subframe comprises:

deriving an integer, N, at least in part by dividing a period of the subframe by a time required for sending the DSBDR message; and

generating a random integer, i, that is uniformly distributed from 0 to N;

wherein causing the DSBDR message to be sent in the determined random interval comprises causing the DSBDR message to be sent in the i'^h time interval of the subframe.

5. The method of any of Claims 1-4, wherein the message requesting to send data on the channel is heard by a first modem of the first terminal and the DSBDR message is sent by a second modem of the first terminal, wherein the first modem uses a first wireless access technology, and wherein the second modem uses a second wireless access technology.

6. The method of any of Claims 1-5, wherein the first D2D communication group and the second D2D communication group are served by the same cellular network access point.

7. The method of any of Claims 1-6, further comprising:

receiving, at the first terminal, data sent by the third terminal over the channel in response to the DSBDR message, and wherein the first D2D group occupies the channel during at least a portion of the period of time during which the channel is reserved by the second terminal.

8. The method of Claim 7, further comprising:

receiving, at the first terminal, D2D pair status information broadcast by a cellular network access point, the D2D pair status information including transmission-reception timeslot assignment information for the second D2D communication group; and

using the transmission-reception timeslot assignment information for the second D2D communication group to coordinate transmissions on the channel by the first D2D

communication group to avoid interfering with any communications that may be sent over the channel by the second D2D communication group.

9. The method of any of Claims 1-8, wherein in an instance in which the third terminal receives a DSBDR message from one or more further terminals in a same subframe in which the third terminal receives the DSBDR message from the first terminal, the third terminal is configured to compare a priority associated with each of the received DSBDR messages and transmit data to the first terminal only in an instance in which the DSBDR message sent by the first terminal is associated with the highest priority.

10. The method of Claim 9, wherein the priority associated with a DSBDR message is pre-defined by a cellular network access point.

1 1. An apparatus comprising:

at least one processor; and at least one memory including computer program code,

the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to at least:

determine, at a first terminal that is a member of a first device-to-device (D2D) communication group, that the first terminal has not heard a clear to send message within a predefined period of time following the first terminal hearing a message requesting to send data on a channel sent by a second terminal that is a member of a second D2D

communication group; and

determine, responsive to determining that the first terminal has not heard a clear to send message within the predefined period of time following the first terminal hearing the message requesting to send data on the channel, to format and send a D2D shared band data request (DSBDR) message to a third terminal requesting the third terminal to send data to the first terminal over the channel during a period of time during which the channel is reserved by the second terminal, wherein the third terminal is a member of the first D2D

communication group.

12. The apparatus of Claim 1 1 , wherein the predefined period of time following the first terminal hearing the message requesting to send data on the channel comprises a Short Interframe Space (SIFS) period.

13. The apparatus of any of Claims 1 1-12, wherein the at least one memory and the computer program code configured to, with the at least one processor, further cause the apparatus to:

determine a random interval of a subframe on the channel; and

cause the DSBDR message to be sent from the first terminal to the third terminal over the channel in the determined random interval of the subframe.

14. The apparatus of Claim 13, wherein the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to determine the random interval of the subframe at least in part by:

generating a random integer, i, that is uniformly distributed from 0 to N; and wherein the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus to cause the DSBDR message to be sent in the determined random interval by causing the DSBDR message to be sent in the i^th time interval of the subframe.

15. The apparatus of any of Claims 11-14, wherein the message requesting to send data on the channel is heard by a first modem of the first terminal and the DSBDR message is sent by a second modem of the first terminal, wherein the first modem uses a first wireless access technology, and wherein the second modem uses a second wireless access technology.

16. The apparatus of any of Claims 11-15, wherein the first D2D communication group and the second D2D communication group are served by the same cellular network access point.

17. The apparatus of any of Claims 11-16, wherein the at least one memory and the computer program code configured to, with the at least one processor, further cause the apparatus to:

receive, at the first terminal, data sent by the third terminal over the channel in response to the DSBDR message, and wherein the first D2D group occupies the channel during at least a portion of the period of time during which the channel is reserved by the second terminal.

18. The apparatus of Claim 17, wherein the at least one memory and the computer program code configured to, with the at least one processor, further cause the apparatus to: receive, at the first terminal, D2D pair status information broadcast by a cellular network access point, the D2D pair status information including transmission-reception timeslot assignment information for the second D2D communication group; and

use the transmission-reception timeslot assignment information for the second D2D communication group to coordinate transmissions on the channel by the first D2D

1 . The apparatus of any of Claims 11-18, wherein in an instance in which the third terminal receives a DSBDR message from one or more further terminals in a same subframe in which the third terminal receives the DSBDR message from the first terminal, the third terminal is configured to compare a priority associated with each of the received DSBDR messages and transmit data to the first terminal only in an instance in which the DSBDR message sent by the first terminal is associated with the highest priority.

20. The apparatus of Claim 19, wherein the priority associated with a DSBDR message is pre-defined by a cellular network access point.

21. The apparatus of any of Claims 11-20, wherein the apparatus is implemented on the first terminal, and wherein the first terminal is configured to be used in a Long Term Evolution cellular network.

22. The apparatus of any of Claims 1 1-21, wherein the apparatus is implemented on the first terminal, the first terminal comprising a mobile phone, wherein the mobile phone further comprises:

user interface circuitry; and

user interface software configured to facilitate user control of at least some functions of the mobile phone through use of a display.

23. A computer program product comprising:

at least one computer readable medium having program code stored thereon, the program code comprising instructions, which when executed by an apparatus, are configured to cause the apparatus to at least:

communication group; and

determine, responsive to determining that the first terminal has not heard a clear to send message within the predefined period of time following the first terminal hearing the message requesting to send data on the channel, to format and send a D2D shared band data request (DSBDR) message to a third terminal requesting the third tenninal to send data to the first terminal over the channel during a period of time during which the channel is reserved by the second terminal, wherein the third terminal is a member of the first D2D communication group.

24. The computer program product of Claim 23, wherein the predefined period of time following the first terminal hearing the message requesting to send data on the channel comprises a Short Interframe Space (SIFS) period.

25. The computer program product of any of Claims 23-24, wherein the program code further comprises instructions configured to cause the apparatus to:

determine a random interval of a subframe on the channel; and

26. The computer program product of Claim 25, wherein the program code further comprises:

instructions configured to cause the apparatus to determine the random interval of the subframe at least in part by:

generating a random integer, i, that is uniformly distributed from 0 to N; and instructions configured to cause the apparatus to cause the DSBDR message to be sent in the determined random interval by causing the DSBDR message to be sent in the i^th time interval of the subframe.

27. The computer program product of any of Claims 23-26, wherein the message requesting to send data on the channel is heard by a first modem of the first terminal and the DSBDR message is sent by a second modem of the first terminal, wherein the first modem uses a first wireless access technology, and wherein the second modem uses a second wireless access technology.

28. The computer program product of any of Claims 23-27, wherein the first D2D communication group and the second D2D communication group are served by the same cellular network access point.

29. The computer program product of any of Claims 23-28, wherein the program code further comprises instructions configured to cause the apparatus to:

30. The computer program product of Claim 29, wherein the program code further comprises instructions configured to cause the apparatus to:

receive, at the first terminal, D2D pair status information broadcast by a cellular network access point, the D2D pair status information including transmission-reception timeslot assignment information for the second D2D communication group; and

31. The computer program product of any of Claims 23-30, wherein in an instance in which the third terminal receives a DSBDR message from one or more further terminals in a same subframe in which the third terminal receives the DSBDR message from the first terminal, the third terminal is configured to compare a priority associated with each of the received DSBDR messages and transmit data to the first terminal only in an instance in which the DSBDR message sent by the first terminal is associated with the highest priority.

32. The computer program product of Claim 31 , wherein the priority associated with a DSBDR message is pre-defined by a cellular network access point.

33. An apparatus comprising:

means for determining, at a first terminal that is a member of a first device-to-device (D2D) communication group, that the first terminal has not heard a clear to send message within a predefined period of time following the first terminal hearing a message requesting to send data on a channel sent by a second terminal that is a member of a second D2D communication group; and means for determining, responsive to determining that the first terminal has not heard a clear to send message within the predefined period of time following the first terminal hearing the message requesting to send data on the channel, to format and send a D2D shared band data request (DSBDR) message to a third terminal requesting the third terminal to send data to the first terminal over the channel during a period of time during which the channel is reserved by the second terminal, wherein the third terminal is a member of the first D2D communication group.

34. The apparatus of Claim 33, wherein the predefined period of time following the first terminal hearing the message requesting to send data on the channel comprises a Short Interframe Space (SIFS) period.

35. The apparatus of any of Claims 33-34, further comprising:

means for determining a random interval of a subframe on the channel; and means for causing the DSBDR message to be sent from the first terminal to the third terminal over the channel in the determined random interval of the subframe.

36. The apparatus of Claim 35, wherein:

the means for determining the random interval of the subframe comprise:

means for deriving an integer, N, at least in part by dividing a period of the subframe by a time required for sending the DSBDR message; and

means for generating a random integer, i, that is uniformly distributed from 0 to N; and

the means for causing the DSBDR message to be sent comprise means for causing the DSBDR message to be sent in the i^th time interval of the subframe.

37. The apparatus of any of Claims 33-36, wherein the message requesting to send data on the channel is heard by a first modem of the first terminal and the DSBDR message is sent by a second modem of the first terminal, wherein the first modem uses a first wireless access technology, and wherein the second modem uses a second wireless access technology.

38. The apparatus of any of Claims 33-37, wherein the first D2D communication group and the second D2D communication group are served by the same cellular network access point.

39. The apparatus of any of Claims 33-38, further comprising:

means for receiving, at the first terminal, data sent by the third terminal over the channel in response to the DSBDR message, and wherein the first D2D group occupies the channel during at least a portion of the period of time during which the channel is reserved by the second terminal.

40. The apparatus of Claim 39, further comprising:

means for receiving, at the first terminal, D2D pair status information broadcast by a cellular network access point, the D2D pair status information including transmission- reception timeslot assignment information for the second D2D communication group; and means for using the transmission-reception timeslot assignment information for the second D2D communication group to coordinate transmissions on the channel by the first D2D communication group to avoid interfering with any communications that may be sent over the channel by the second D2D communication group.

41. The apparatus of any of Claims 33-40, wherein in an instance in which the third terminal receives a DSBDR message from one or more further terminals in a same subframe in which the third terminal receives the DSBDR message from the first terminal, the third terminal is configured to compare a priority associated with each of the received DSBDR messages and transmit data to the first terminal only in an instance in which the DSBDR message sent by the first terminal is associated with the highest priority.

42. The apparatus of Claim 41, wherein the priority associated with a DSBDR message is pre-defined by a cellular network access point.