Abstract:
A method of enabling terminal-to-terminal communication includes organizing a cluster including a cluster head, a first cluster member, and a second cluster member. The first cluster member includes a first terminal. The second cluster member includes a second terminal. The cluster head is connected to the first cluster member and the second cluster member. The method further includes controlling a unicast communication from the first cluster member to the second cluster member via the cluster head.

Description:
FIELD 
       [0001]    The embodiments discussed herein are related to terminal-to-terminal communication. 
       BACKGROUND 
       [0002]    Terminal-to-terminal communication may allow data transmissions to be made directly between two or more terminals of a telecommunication system. The terminal-to-terminal communication may overlay regular cellular communications, and may be performed with or without cellular network coverage. In some instances, using terminal-to-terminal communication may increase network capacity. For example, terminal-to-terminal communication may permit spatial multiplexing, which may allow for higher relative spectrum usage. Employing terminal-to-terminal communication may also permit throughput between terminals to be increased if a terminal-to-terminal link experiences better channel quality than a cellular link. Using terminal-to-terminal communication may reduce resource usage when data is transmitted once between two terminals during a terminal-to-terminal transmission, as compared to transmitting the same data twice between the two terminals over a cellular link, i.e., once through an uplink (UL) transmission from a transmitting terminal to a base station and once through a downlink (DL) transmission to a receiving terminal from the base station. Terminal-to-terminal communication may reduce communication latency of a telecommunication network. For example, terminal-to-terminal communication may not relay data through a base station and/or a core network, thus potentially reducing the transit time of the data and/or the load on the base station and/or the core network. The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate one example technology area where some embodiments described herein may be practiced. 
       SUMMARY 
       [0003]    According to an aspect of an embodiment, a method of enabling terminal-to-terminal communication includes organizing a cluster including a cluster head, a first cluster member, and a second cluster member. The first cluster member includes a first terminal. 
         [0004]    The second cluster member includes a second terminal. The cluster head is connected to the first cluster member and the second cluster member. The method further includes controlling a unicast communication from the first cluster member to the second cluster member via the cluster head. 
         [0005]    The object and advantages of the embodiments will be realized and achieved at least by the elements, features, and combinations particularly pointed out in the claims. 
         [0006]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Example embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0008]      FIG. 1  is a diagrammatic view of an example telecommunication system; 
           [0009]      FIG. 2  is a diagrammatic view of an example cluster that may be implemented in the telecommunication system of  FIG. 1 ; 
           [0010]      FIG. 3  is a diagrammatic view of an example communication process between a cluster head, a cluster member transmitter, and a cluster member receiver that may be implemented in the cluster of  FIG. 2 ; 
           [0011]      FIG. 4A  is a diagrammatic view of an example channel scheme between a terminal cluster head, a cluster member transmitter, and a cluster member receiver that may be implemented in the cluster of  FIG. 2 ; and 
           [0012]      FIG. 4B  is a diagrammatic view of an example channel scheme between a base station cluster head, a cluster member transmitter, and a cluster member receiver that may be implemented in the cluster of  FIG. 2 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0013]    Some embodiments described herein may relate to a telecommunication system based on the 3rd Generation Partnership Project&#39;s (3GPP) Long Term Evolution (LTE) radio access network. Descriptions involving LTE may also apply to 3GPP&#39;s Long Term Evolution Advanced (LTE-A) radio access network. However, the embodiments described herein are not limited to the example telecommunication systems described. Rather, the embodiments described herein may also be applicable to other telecommunication systems. Some embodiments may relate to performing and/or enabling terminal-to-terminal communication in a telecommunication system. The terminal-to-terminal communication may occur with or without cellular network coverage. 
         [0014]    Embodiments of the present invention will be explained with reference to the accompanying drawings. 
         [0015]      FIG. 1  is a diagrammatic view of an example telecommunication system  100 , arranged in accordance with at least one embodiment described herein. In some embodiments, a network architecture of the telecommunication system  100  may include the network architecture of an Evolved Universal Mobile Telecommunications System (E-UMTS). The E-UMTS may include an LTE radio access network, for instance. The radio access network may include an E-UMTS Terrestrial Radio Access Network (E-UTRAN). However, other types of network architecture may alternately or additionally be used. 
         [0016]    The telecommunication system  100  may include a base station  102 . The base station  102  may include base station equipment, including hardware and/or software for radio communication with radio-communication-equipped nodes (“wireless nodes”). For example, the base station  102  may be equipped for radio communication  110  with wireless nodes such as terminal  104   a,  terminal  104   b,  and terminal  104   c  (collectively “terminals  104 ”). The base station  102  may generally allow the wireless nodes, including the terminals  104 , to wirelessly communicate with each other and/or to wirelessly access a network (not shown) via radio communication  110  with the base station  102 . 
         [0017]    The base station  102  may include hardware and software for radio communication over a licensed spectrum. The licensed spectrum may generally include portions of a radio spectrum licensed for transmission of wireless data, such as cellular data. For example, the base station  102  may be configured to transmit cellular data that complies with an LTE radio access network, such as an LTE radio access network according to 3GPP LTE specification releases 8-12. The base station  102  may include an E-UTRAN NodeB (eNB) associated with LTE radio access networks. 
         [0018]    The terminals  104  may include equipment configured to allow the terminals  104  to transmit and receive data via wireless communications via the licensed spectrum. For example, the terminals  104  may include hardware, such as one or more antennas for transmitting and receiving radio transmissions, and codecs. The terminals  104  may include mobile phones, tablet computers, laptop computers, and/or other electronic devices that may use radio communication. Alternately or additionally, the terminals  104  may include devices that employ machine-type communication (MTC). The terminals  104  may include user equipment (UE) associated with LTE radio access networks. 
         [0019]    Each of the terminals  104  may include memory  106  and a processor  108 . The memory  106  may include a non-transitory computer-readable medium. Instructions such as programming code executable by the processor  108  may be encoded in the memory  106 . When the instructions are executed by the processor  108 , the associated terminals  104   a,    104   b,  and  104   c  may perform operations related to and/or including the processes described herein. The terminals  104  may be equipped for terminal-to-terminal communication  112 , which may include device-to-device (D2D) communication associated with LTE radio access networks. The terminal-to-terminal communication  112  may allow the terminals  104  to transmit and/or receive data among the terminals  104  without routing the data through the base station  102 . 
         [0020]      FIG. 2  is a diagrammatic view of an example cluster  200 . In some embodiments, the cluster  200  may be implemented in the telecommunication system  100  of  FIG. 1 . The cluster  200  may include a cluster head  202 . The cluster  200  may also include a cluster member  206   a,  a cluster member  206   b,  a cluster member  206   c,  and a cluster member  206   d  (collectively “cluster members  206 ”). The cluster members  206  may be terminals generally corresponding to the terminals  104  of  FIG. 1 . The cluster members  206  may be within a transmission range  204  of the cluster head  202 . The cluster members  206  may be communicatively associated with the cluster head  202 , described herein as being connected to the cluster head  202 . The cluster members  206  may or may not be within a transmission range (not shown) of each of the other cluster members  206 . The cluster  200  may enable cluster-member-to-cluster-member communication  210 . The cluster-member-to-cluster-member communication  210  may generally correspond to the terminal-to-terminal communication  112  of  FIG. 1 . 
         [0021]    In some embodiments, the cluster head  202  may be a base station generally corresponding to the base station  102  of  FIG. 1 . For example, a base station may be the cluster head  202  for cluster members  206  located within a cell generally corresponding to the transmission range  204  of the base station. In embodiments including a base station as the cluster head  202 , a cluster-member-to-cluster-head communication  208  may generally correspond to the radio communication  110  of  FIG. 1 . In some embodiments, when the cluster head  202  is a base station, one or more terminals connected to the base station for cellular communication may be cluster members  206 . 
         [0022]    Alternately, the cluster head  202  may be a terminal generally corresponding to the terminals  104  of  FIG. 1 . For example, a terminal may be the cluster head  202  for cluster members  206  located within a transmission range  204  of the cluster head  202 . The cluster head  202  and/or one or more of the cluster members  206  may be outside of cellular network coverage, e.g., the cluster head  202  and/or one or more of the cluster members  206  may be outside of a transmission range of a base station. In embodiments including a terminal as the cluster head  202 , the cluster-member-to-cluster-head communication  208  may generally correspond to the terminal-to-terminal communication  112  of  FIG. 1 . 
         [0023]    In some embodiments, one or more of the cluster members  206  may be identified via a cluster member identification. The cluster head  202  may assign the cluster member identification. If the cluster head  202  is a base station, the cluster member identification may include a cell radio-network temporary identifier (C-RNTI) associated with LTE radio access networks. If the cluster head  202  is a terminal, the cluster member identification may include a D2D radio-network temporary identifier (D2D-RNTI). 
         [0024]    Connectivity between the cluster head  202  and the cluster members  206 , and/or connectivity among the cluster members  206  may depend on a transmission power of the cluster head  202 . In some embodiments, the transmission power of the cluster head  202  may be adjusted based on a number of terminals within the transmission range  204  of the cluster head  202 . The transmission power of the cluster head  202  may be reduced to reduce the size of the transmission range  204  and potentially reduce the number of cluster members  206  in the cluster  200 . Alternately, the transmission power of the cluster head  202  may be increased to increase the size of the transmission range  204  and potentially increase the number of cluster members  206  in the cluster  200 . 
         [0025]    The cluster members  206  may set a default transmission power associated with the cluster  200 . The default transmission power of each of the cluster members  206  may be based on an estimated path loss between each of the cluster members  206  and the cluster head  202 . The estimated path loss between each of the cluster members  206  and the cluster head  202  may be based on a cluster beacon transmitted by the cluster head  202 . The cluster beacon may advertise the existence of the cluster  200  and may be used for synchronization by the cluster members  206 . In some embodiments, a link budget between each of the cluster members  206  and the cluster head  202  may be roughly symmetric. 
         [0026]    Alternately or additionally, the default transmission power of each of the cluster members  206  associated with the cluster  200  may be based on power control commands transmitted by the cluster head  202 . For example, with respect to the cluster member  206   a,  the cluster head  202  may monitor a signal received from the cluster member  206   a  and may transmit a power control command to the cluster member  206   a  based on the signal received from the cluster member  206   a.    
         [0027]    The default transmission powers of each of the cluster members  206  in the cluster  200  may be different. The cluster members  206  may perform cluster-member-to-cluster-member communication  210  directly between two or more cluster members  206 . The cluster-member-to-cluster-member communication  210  may generally correspond to the terminal-to-terminal communication  112  of  FIG. 1 . 
         [0028]    In some embodiments, the cluster head  202  may manage the cluster-member-to-cluster-member communication  210  within the cluster  200 . The high received power threshold and/or the low received power threshold may be configured by the cluster head  202  through the RRC. For example, the cluster head  202  may set a high received power threshold and/or a low received power threshold for a particular cluster-member-to-cluster-member communication  210 . Alternately, the cluster head  202  may set the high received power threshold and/or the low received power threshold for all or a subset of all the cluster-member-to-cluster-member communication  210  in the cluster  200 . 
         [0029]    The high received power threshold may be represented by the symbol Th H . The high received power threshold may represent a power above which a cluster-member-to-cluster-member communication  210  may be successfully received by the cluster members  206  in a bidirectional link. By way of example, a bidirectional link between the cluster member  206   a  and the cluster member  206   b  may allow cluster-member-to-cluster-member communication  210  between the cluster member  206   a  and the cluster member  206   b.  Both the cluster member  206   a  and the cluster member  206   b  may successfully receive the cluster-member-to-cluster-member communication  210  if the cluster-member-to-cluster-member communication  210  is received with a power equal to or above the high received power threshold. 
         [0030]    The low received power threshold may be represented by the symbol Th L . The low received power threshold may represent a power below which an attempted cluster-member-to-cluster-member communication  210  may be unsuccessfully received and/or not received by the cluster members  206  in an interference link. By way of example, an interference link between the cluster member  206   a  and the cluster member  206   b  may not allow cluster-member-to-cluster-member communication  210  between the cluster member  206   a  and the cluster member  206   b.  In some embodiments, an interference link may not be used in cluster-member-to-cluster-member communication  210 . 
         [0031]    A path loss between two of the cluster members  206  may be represented by a symbol PL. 
         [0032]    By way of example, a path loss between the cluster member  206   a  and the cluster member  206   b  may be represented by the symbol PL a-b . 
         [0033]    A default transmission power associated with the cluster  200  by the cluster member  206   a  may be represented by a symbol P D   a  and a default transmission power associated with the cluster  200  by the cluster member  206   b  may be represented by a symbol P D   b . 
         [0034]    A cluster-member-to-cluster-member communication  210  transmitted by the cluster member  206   b  at the cluster member  206   b  default transmission power may be received at the cluster member  206   a  at a received power represented by PL a-b ·P D   b . Conversely, the power of a cluster-member-to-cluster-member communication  210  received at the cluster member  206   b  when transmitted from the cluster member  206   a  at the cluster member  206   a  default power may be represented by PL a-b ·P D   a . 
         [0035]    The cluster member  206   a  and the cluster member  206   b  may have a bidirectional link as a result of the cluster-member-to-cluster-member communication  210  being received at both the cluster member  206   a  and the cluster member  206   b  with received power equal to or greater than the high received power threshold. Put another way, the cluster member  206   a  and the cluster member  206   b  may have a bidirectional link at the default transmission powers of the cluster member  206   a  and the cluster member  206   b  when the following formula 1 and formula 2 are both true. 
         [0000]        PL   a-b   ·P   D   b   ≧Th   H    Formula 1:
 
         [0000]        PL   a-b   ·P   D   a   ≧Th   H    Formula 2:
 
         [0036]    In some embodiments, if one or both of formula 1 and formula 2 are not true, the transmission power of the cluster member  206   a  may be increased and/or the transmission power of the cluster member  206   b  may be increased such that the cluster-member-to-cluster-member communication  210  is received at the cluster member  206   a  and at the cluster member  206   b  with a received power equal to or greater than the high received power threshold. Put another way, the cluster members  206  may change the transmission power of the cluster-member-to-cluster-member communication  210  to form bidirectional links. 
         [0037]    The cluster members  206  may exchange cluster-member-to-cluster-member communication  210  over the bidirectional links. 
         [0038]    The cluster member  206   a  and the cluster member  206   b  may have a unidirectional link as a result of the power of the cluster-member-to-cluster-member communication  210  being received at only one of the cluster member  206   a  and the cluster member  206   b  with a received power greater than or equal to the high received power threshold. In some embodiments, a unidirectional link may be used for one-way cluster-member-to-cluster-member communication  210 . In these and other embodiments, one or more of the cluster members  206  may change the transmission power of the cluster-member-to-cluster-member communication  210  to turn the unidirectional links into bidirectional links. 
         [0039]    The cluster member  206   a  and the cluster member  206   b  may have an interference link as a result of the power of the cluster-member-to-cluster-member communication  210  being received at both the cluster member  206   a  and the cluster member  206   b  with a received power less than or equal to the low received power threshold. In some embodiments, the interference links may not be used by the cluster members  206  for cluster-member-to-cluster-member communication  210 . Alternately or additionally, the cluster members  206  may change the transmission power of the cluster-member-to-cluster-member communication  210  to turn the interference links into unidirectional links and/or bidirectional links. 
         [0040]      FIG. 3  is a diagrammatic view of an example communication process  300  between a cluster head  302 , a cluster member transmitter  304 , and a cluster member receiver  306  that may be implemented in the cluster  200  of  FIG. 2 . The cluster head  302  may generally correspond to the cluster head  202  of  FIG. 2 . The cluster member transmitter  304  and the cluster member receiver  306  may generally correspond, respectively, to the cluster member  206   a  and the cluster member  206   b.    
         [0041]    In some embodiments, the terminal-to-terminal communication may be performed as one or more unicast sessions. For example, the communication process  300  may represent a one-way data transmission from the cluster member transmitter  304  to the cluster member receiver  306 . In some embodiments, a communication process (not shown) similar to the communication process  300  may be performed to transmit data from the cluster member receiver  306  to the cluster member transmitter  304  by reversing the roles of the cluster member transmitter  304  and cluster member receiver  306 . 
         [0042]    In some embodiments, the cluster head  302  may allocate resources for the unicast session in a manner similar to or the same as semi-persistent scheduling (SPS) associated with LTE radio access networks. Performing a terminal-to-terminal communication as one or more unicast sessions and/or in a manner similar to or the same as SPS may promote an efficient use of resources and/or an efficient use of power at the cluster head  302 . Other scheduling schemes, e.g., dynamic scheduling associated with LTE radio access networks, may alternately or additionally be used. 
         [0043]    The communication process  300  may begin with the cluster member transmitter  304  transmitting a request for resources  308 . The resources may be requested for a terminal-to-terminal communication generally corresponding to the cluster-member-to-cluster-member communication  210  of  FIG. 2  to be performed as a unicast session between the cluster member transmitter  304  and the cluster member receiver  306 . 
         [0044]    The cluster head  302  may respond by transmitting a control indicator  310 . The control indicator  310  may identify allocated resources. The control indicator  310  may be broadcast by the cluster head  302  such that the control indicator  310  is received by both the cluster member transmitter  304  and the cluster member receiver  306 . In some embodiments, the control indicator  310  may include a cluster number temporary identification (CNTI) assignment to the cluster member transmitter  304  and/or a CNTI assignment to the cluster member receiver  306 . Alternately or additionally, the cluster head  302  may transmit a D2D unicast radio-network temporary identifier (D2D-U-RNTI) associated with the unicast session between the cluster member transmitter  304  and the cluster member receiver  306 . 
         [0045]    In some embodiments, the allocated resources may include physical resources, a resource period, and/or a resource duration. The physical resources may include terminal-to-terminal data transmission resources and terminal-to-terminal feedback resources. The terminal-to-terminal feedback resources may be implicitly identified relative to the terminal-to-terminal data transmission resources. 
         [0046]    The terminal-to-terminal data transmission resources may be used by the cluster member transmitter  304  to transmit terminal-to-terminal data transmissions  311  to the cluster member receiver  306 . 
         [0047]    The terminal-to-terminal feedback resources may be used by the cluster member receiver  306  to transmit acknowledgements  312  in response to the terminal-to-terminal data transmissions  311 . The acknowledgements  312  may include a positive acknowledgement (ACK) configured to indicate that the terminal-to-terminal data transmissions  311  were successfully received by the cluster member receiver  306 . Alternately or additionally, the acknowledgements  312  may include a negative acknowledgement (NACK) configured to indicate that the terminal-to-terminal data transmissions  311  were not successfully received. 
         [0048]    In some embodiments, the terminal-to-terminal data transmissions  311  and/or the acknowledgements  312  may be based on a hybrid automatic repeat-request (HARQ) scheme associated with the LTE radio access network. The cluster member transmitter  304  and the cluster member receiver  306  may maintain a HARQ process autonomously. 
         [0049]    The cluster member transmitter  304  may transmit the terminal-to-terminal data transmissions  311  according to the allocated resources. The cluster member receiver  306  may also transmit the acknowledgements  312  according to the allocated resources. 
         [0050]    The cluster member transmitter  304  may optionally retransmit one or more of the terminal-to-terminal data transmissions  311  with a different modulation and coding scheme (MCS) based on the acknowledgements  312  received. 
         [0051]    In some embodiments, the communication process  300  may include cluster-member-to-cluster-head feedback. The allocated resources may include cluster-member-to-cluster-head feedback resources. The cluster-member-to-cluster-head feedback resources may include periodic resources. 
         [0052]    The cluster member transmitter  304  may transmit feedback  313  including a transmission status of the terminal-to-terminal data transmissions  311  to the cluster head  302  via the cluster-member-to-cluster-head feedback resources. The transmission status may include a terminal-to-terminal data transmission queue status, information about the transmission quality of the terminal-to-terminal data transmissions  311 , a transmission power of the terminal-to-terminal data transmissions  311 , or the like or any combination thereof. The information about the quality of the terminal-to-terminal data transmissions  311  may include statistics related to the ACKs and NACKs received via the acknowledgements  312 . 
         [0053]    The cluster member receiver  306  may also transmit feedback  314  including a reception status of the terminal-to-terminal data transmissions  311  to the cluster head  302  via the cluster-member-to-cluster-head feedback resources. The reception status may include information about the transmission quality of the terminal-to-terminal data transmissions  311 , a signal-to-interference-and-noise-ratio (SINR), or the like or any combination thereof. The information about the quality of the terminal-to-terminal data transmissions  311  may include statistics related to the ACKs and NACKs transmitted via the acknowledgements  312 . 
         [0054]    In some embodiments, the cluster head  302  may transmit a control indicator  315 . The control indicator  315  may identify updated allocated resources generally corresponding to the allocated resources used to communicate the terminal-to-terminal data transmissions  311  and the acknowledgements  312 . The updated allocated resources may be changed from the allocated resources based on the feedback  313 , the feedback  314 , available terminal-to-terminal communication resources, demand for the available terminal-to-terminal communication resources, or the like or any combination thereof. The control indicator  315  may be broadcast by the cluster head  302  such that the control indicator  315  is received by the cluster member transmitter  304  and the cluster member receiver  306 . 
         [0055]    Alternately or additionally, the control indicator  315  may instruct the cluster member transmitter  304  to adjust the transmission power of transmissions to the cluster member receiver  306 . 
         [0056]    In response to receiving the control indicator  315 , the cluster member transmitter  304  may transmit terminal-to-terminal data transmissions  316  via the updated allocated resources. The terminal-to-terminal data transmissions  316  may generally correspond to the terminal-to-terminal data transmissions  311 . 
         [0057]    In response to the terminal-to-terminal data transmissions  316 , the cluster member receiver  306  may transmit acknowledgements  317  via the updated allocated resources. The acknowledgements  317  may generally correspond to the acknowledgements  312 . 
         [0058]    In some embodiments, the process of updating the allocated resources may continue until the cluster member transmitter  304  has successfully transmitted the data transmissions associated with the unicast session. 
         [0059]    In some embodiments, the cluster member transmitter  304  may transmit feedback  318  generally corresponding to the feedback  313 . The cluster member receiver  306  may also transmit feedback  319  generally corresponding to the feedback  314 . 
         [0060]    In some embodiments, the cluster head  302  may transmit a control indicator  320  including a termination signal. The control indicator  320  may be received by the cluster member transmitter  304  and the cluster member receiver  306 . The termination signal of the control indicator  320  may inform the cluster member transmitter  304  and the cluster member receiver  306  that the allocated resources and/or the updated allocated resources are no longer allocated for a terminal-to-terminal unicast from the cluster member transmitter  304  to the cluster member receiver  306 . The termination signal may be included in the control indicator  320  based on the feedbacks  318  and  319 . The termination signal may be transmitted after the cluster member transmitter  304  has no more data transmissions to transmit to the cluster member receiver  306 , if the terminal-to-terminal data transmissions  316  are not being received successfully by the cluster member receiver  306 , or the like. 
         [0061]    In some embodiments, the termination signal may not be used to end the example communication process  300 . For example, the example communication process  300  may end after the duration of the allocated resources and/or the updated allocated resources are reached. 
         [0062]      FIG. 4A  is a diagrammatic view of an example channel scheme  400  between a terminal cluster head  402 , a cluster member transmitter  404 , and a cluster member receiver  406  that may be implemented in the cluster  200  of  FIG. 2 . The terminal cluster head  402  may generally correspond to the terminal  104   a  of  FIG. 1 , the cluster head  202  of  FIG. 2 , and/or the cluster head  302  of  FIG. 3 . The cluster member transmitter  404  may generally correspond to the terminal  104   b  of  FIG. 1 , the cluster member  206   a  of  FIG. 2  and/or the cluster member transmitter  304  of  FIG. 3 . The cluster member receiver  406  may generally correspond to the terminal  104   c  of  FIG. 1 , the cluster member  206   b  of  FIG. 2 , and/or the cluster member receiver  306  of  FIG. 3 . 
         [0063]    In some embodiments, the channel scheme  400  may be employed in an LTE radio access network. The channel scheme  400  may optionally be employed in performing the communication process  300  of  FIG. 3 . 
         [0064]    The channel scheme  400  may include a D2D physical control channel (D2D-PCCH)  408 . In some embodiments, the terminal cluster head  402  may transmit the control indicators  310 ,  315 , and  320  of  FIG. 3  via the D2D-PCCH  408 . The cluster member transmitter  304  and the cluster member receiver  306  of  FIG. 3  may monitor the D2D-PCCH  408  for the control indicators  310 ,  315 , and  320 . Other control signals may alternately or additionally be transmitted via the D2D-PCCH  408 . 
         [0065]    The channel scheme  400  may further include a D2D physical shared channel (D2D-PSCH)  410 . The terminal cluster head  402  may allocate D2D-PSCH  410  resources for use by the cluster member transmitter  404  and/or the cluster member receiver  406  to transmit the terminal data transmissions  311  and  316 , and/or the feedbacks  313 ,  314 ,  318 , and  319  of  FIG. 3 . 
         [0066]    In some embodiments, the cluster member transmitter  404  may use the D2D-PSCH  410  to transmit the request for resources  308  of  FIG. 3 . Resources for transmitting the request for resources  308  may be allocated via an in-cluster random access, a periodic allocation, or the like. 
         [0067]    The channel scheme  400  may further include a D2D physical feedback channel (D2D-PFBK)  412 . The terminal cluster head  402  may allocate D2D-PFBK  412  resources for use by the cluster member transmitter  404  and/or the cluster member receiver  406  to transmit the acknowledgements  312  and  317 , and/or the feedbacks  313 ,  314 ,  318 , and  319  of  FIG. 3 . 
         [0068]    Alternately or additionally, the terminal cluster head  402  may transmit the control indicators  310 ,  315 , and  320  via the D2D-PSCH  410  and/or the D2D-PFBK  412 . For example, the terminal cluster head  402  may transmit the control indicator  310  and the control indicators  310 ,  315 , and  320  using an SPS scheme via the D2D-PSCH. 
         [0069]    In these and other embodiments, additional logic channels and/or transport channels may be used. For example, logic channels such as a D2D logic control channel (D2D-LCCH) and a D2D dedicated traffic channel (D2D-DTCH) may be used to carry terminal-to-terminal control traffic and dedicated terminal-to-terminal traffic, respectively. A transport channel such as a D2D shared channel (D2D-SCH) may be dedicated for D2D data traffic. 
         [0070]      FIG. 4B  is a diagrammatic view of an example channel scheme  450  between a base station cluster head  452 , the cluster member transmitter  404 , and the cluster member receiver  406  that may be implemented in the cluster  200  of  FIG. 2 . The channel scheme  450  includes some elements that are similar or identical to elements of the channel scheme  400  of  FIG. 4A , such as the cluster member transmitter  404 , the cluster member receiver  406 , the D2D-PSCH  410 , and the D2D-PFBK  412 , for which a more detailed description is already provided above. 
         [0071]    The base station cluster head  452  may generally correspond to the base station  102  of  FIG. 1 , the cluster head  202  of  FIG. 2 , and/or the cluster head  302  of  FIG. 3 . In some embodiments, the channel scheme  450  may be employed in an LTE radio access network. The channel scheme  450  may be employed in performing the communication process  300  of  FIG. 3 . 
         [0072]    The channel scheme  450  may include a physical downlink shared channel (PDSCH)  454  associated with LTE radio access networks. In some embodiments, the base station cluster head  452  may transmit the control indicators  310 ,  315 , and  320  of  FIG. 3  via the PDSCH  454 . Other control signals may alternately or additionally be transmitted via the PDSCH  454 . 
         [0073]    The channel scheme  450  may alternately or additionally include a physical uplink shared channel (PUSCH)  456  associated with LTE radio access networks. In some embodiments, the cluster member transmitter  404  may use the PUSCH  454  to transmit the request for resources  308  of  FIG. 3 . The cluster member transmitter  404  and/or the cluster member receiver  406  may use the PUSCH  454  to transmit the feedbacks  313 ,  314 ,  318 , and  319  of  FIG. 3 . 
         [0074]    The embodiments described herein may include the use of a special purpose or general purpose computer including various computer hardware or software modules, as discussed in greater detail below. 
         [0075]    Embodiments described herein may be implemented using computer-readable media for carrying or having computer-executable instructions or data structures stored thereon. Such computer-readable media may be any available media that may be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media may include non-transitory computer-readable storage media including Random Access Memory (RAM), Read-Only Memory (ROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Compact Disc Read-Only Memory (CD-ROM) or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory devices (e.g., solid state memory devices), or any other storage medium which may be used to carry or store desired program code in the form of computer-executable instructions or data structures and which may be accessed by a general purpose or special purpose computer. Combinations of the above may also be included within the scope of computer-readable media. 
         [0076]    Computer-executable instructions may include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing device (e.g., one or more processors) to perform a certain function or group of functions. 
         [0077]    Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. 
         [0078]    Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. 
         [0079]    As used herein, the terms “module” or “component” may refer to specific hardware implementations configured to perform the operations of the module or component and/or software objects or software routines that may be stored on and/or executed by general purpose hardware (e.g., computer-readable media, processing devices, etc.) of the computing system. In some embodiments, the different components, modules, engines, and services described herein may be implemented as objects or processes that execute on the computing system (e.g., as separate threads). While some of the system and methods described herein are generally described as being implemented in software (stored on and/or executed by general purpose hardware), specific hardware implementations or a combination of software and specific hardware implementations are also possible and contemplated. In this description, a “computing entity” may be any computing system as previously defined herein, or any module or combination of modulates running on a computing system. 
         [0080]    All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Although embodiments of the present inventions have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.