Patent Publication Number: US-9900798-B2

Title: Polling and reporting mechanism

Description:
TECHNICAL FIELD 
     This disclosure relates generally to improving transmission quality and/or energy efficiency in networks and, more particularly, to methods, devices, and computer program products for polling and status reporting in a wireless network. 
     BACKGROUND 
     3GPP Long Term Evolution (LTE) is a standard for mobile device network technology. LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS), and is a technology for realizing high-speed packet-based communication that can reach high data rates on both downlink and uplink channels. 
     The current Radio Link Control (RLC) protocol in LTE and HSPA defines a polling bit, which triggers a status message transmission in the receiver peer, unless it has already been triggered. Typically, the status message will be transmitted back to the transmitter peer immediately, or as soon as possible. However, if either a reordering timer or a status prohibit timer is running, the transmission of the status may be delayed. The reordering timer may be started, for instance, whenever a gap in sequence numbers is detected and its expiration may trigger a status report to be sent from the receiver peer to the transmitter peer. The status prohibit timer is started whenever a status is sent. 
     The 3GPP specification provides a description of polling in an Acknowledged Mode (AM) receiver. For instance, 3GPP TS 36.322, Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Link Control (RLC) protocol specification, version 11.0.0, sub-clause 5.2 specifies the Automatic Repeat-reQuest (ARQ) procedures used for AM data transfer. As described in the standard&#39;s specification, the AM RLC entity polls its peer AM RLC entity in order to trigger STATUS reporting at the peer. Upon assembly of a new Acknowledged Mode Data (AMD) Protocol Data Unit (PDU), the transmitting side of an AM RLC will increment the value of “PDU_WITHOUT_POLL” by one, and increment the value of “BYTE_WITHOUT_POLL” by the number of contained bytes. If either PDU_WITHOUT_POLL is greater than or equal to a value, pollPDU, or the counter “BYTE_WITHOUT_POLL” is greater than or equal to a value, “pollByte,” a poll will be triggered. Further, if both the transmission buffer and the retransmission buffer are emptied, or if no new RLC data PDU can be transmitted, e.g., due to window stalling, or a counter t-PollRetransmit expiring, while conditions for “Last Data Poll” persist, a poll will be triggered. According to the standard, the RLC AM entity maintains a variable RETX_COUNT to count the number of retransmissions of an AMD PDU. Presently, there is one RETX_COUNT counter per PDU that is retransmitted. 
     The pollPDU and pollByte are optional thresholds which are configured by the radio resource layer in the evolved nodeB (eNodeB), using Radio Resource Control (RRC) signalling to configure the transmitter in the user equipment (UE). These thresholds are set per each RLC AM entity. The transmitting side of an RLC AM entity will start or restart t-PollRetransmit each time it delivers a PDU including a poll to a lower layer, i.e., the timer is (re)started on the transmission occasion. At the same time, the entity remembers the sequence number (SN) of the PDU for which the poll was set, as outlined in 3GPP TS 36.322, subclause 5.2.2.1 (“set POLL_SN to VT(S)—1”). The t-PollRetransmit timer is stopped upon reception of a STATUS report comprising either a positive or a negative acknowledgement for the RLC data PDU with sequence number equal to POLL_SN. A positive acknowledgement (confirmation of successful reception) is used to advance the transmitter window and to send an indication of successful delivery to higher layers. A negative acknowledgement (notification of reception failure) will make the transmitter retransmit, thereby restarting the timer as described above. This occurs only if the SN of the corresponding RLC PDU is within the transmitter window. For instance, it could have been already acknowledged and used to advance the transmitter window. Also, the above only occurs if the RETX_COUNT has not exceeded the maxRetxThreshold that corresponds to the PDU. 
     In Section 5.2.3, 3GPP TS 36.322 also provides a description of status reporting. The acknowledgements of received PDUs or byte segments of PDUs are sent in Status Reports. There are two types of triggers for such reporting.
         Transmitter triggers: The receiver may be explicitly polled by the transmitter as described above. The transmitter&#39;s aim is to progressively report successful delivery to higher layers and advance its transmission window. It cannot do that without continuous feedback from the receiver (positive acknowledgements).   Receiver triggers: The receiver itself may trigger status reporting when detecting a reception failure, appearing as a gap in the SNs of successfully received PDUs. The receiver&#39;s aim is to progressively advance its receiving window by reassembling SDUs for further delivery through higher layers. The gap effectively hinders it from delivering out-of-order SDUs. The gap cannot be filled unless the transmitter performs retransmission of the missing parts. Thus, the receiver supervises the occurrence of one or more gaps with a timer, t-Reordering, which is set proportionately to avoid short-cutting retransmission schemes of lower layers. Status reporting will be triggered if the gap still occurs at the time of t-Reordering&#39;s expiration. The timer is stopped when gap(s) cease to exist.       

     The RLC receiver sends a STATUS PDU if each of the following are fulfilled:
         status reporting is triggered (as described above);   it is allowed to send status (t-StatusProhibit is not running); and   a transmission opportunity is provided.
 
The receiving side of an RLC AM entity will start or restart the t-StatusProhibit timer each time it delivers a PDU, including status to lower layer. In other words, the timer is (re)started with the transmission occasion. Values for t-StatusProhibt are enumerated in 3GPP 36.331.
       

     3GPP 36.322, Section 6.2.2.11 describes a Polling bit (P) field. Presently, the P field indicates whether or not the transmitting side of an AM RLC entity requests a STATUS report from its peer AM RLC entity. Specifically, a Status Report is requested if P=1. The poll is sent by sending a message with the P bit set in the RLC PDU or RESEG PDU header based on triggers described above. The poll is usually sent along with the transmission of a new data PDU. The poll may also be sent along with a retransmission of a previously sent AMD PDU or RESEG PDU if the “Last Data Poll” trigger is activated, i.e., no new data can be sent. 
     SUMMARY 
     According to some embodiments, methods, devices, and computer program products have been developed that provide mechanisms for polling and reporting status in a network. 
     In many communication systems, the control procedures that are frequently performed are of a request-respond type, for instance, on the signaling radio bearers (SRB 1  or SRB 2 ) in LTE. For example, according to a request-response model, a base station, such as an evolved Node B (eNodeB), may request that a wireless communication device, such as a UE, perform an action and then wait for a confirmation that the action has been completed. 
     On the lower layers, such as, for example, the Radio Link Control (RLC) layer in a Control Plane Stack or a User Plane Stack, there are protocols that operate in such a request-respond manner. For instance, on the RLC layer when the Acknowledged Mode (AM) is used, the transmitter and receiver use mechanisms called polling and status reporting to inform each other on their respective transmission and reception statuses. Since the processing times are different on the different layers (longer in the higher up layers of the protocol stack, typically) the different requests and responses cause the UE to make several separate transmissions to inform the different protocol layers of the reception status. This behavior may cause redundant access requests on the random access channel or otherwise and increased power consumption in general. 
     According to some embodiments, mechanisms to delay responding to a received request for status information (“a polling request”) or the triggering or transmission of a status message caused by a reception of a polling request, or to delay the triggering or transmission of the polling request itself are provided, such that redundant transmissions may be minimized, power consumption may be optimized, and network load may be reduced, for instance, load on the random access channel of an eNodeB. 
     In some embodiments, a method for reporting status in a network is provided, which includes receiving, at a control entity of a first stack layer of a first device, a first message from a second device that comprises a set of data and an indicator requesting status information. The method also includes determining, at the control entity, status information of the first device and obtaining a second set of data from a second stack layer of the first device. The method also includes transmitting, from the control entity, a response message to the second device in response to a transmission triggering event, where the response message comprises both the status information and at least a portion of the second set of data. The response message may be, for example, a concatenation of the status information and a portion of the second set of data. 
     In some embodiments, the method may further comprise starting or resetting a timer of the first device in response to receiving the first message, such as a status prohibit timer, a reordering timer, or a status reporting delay timer. According to some aspects, the transmission triggering event of the method may be a specified time lapse of expiration of the timer. 
     In some embodiments, a device comprising a processor and a memory is provided, and the memory contains instructions executable by the processor whereby the device is operative to receive, at a control entity of a first stack layer of the device, a first message from a second device that comprises a set of data and an indicator requesting status information. The device is operative to determine, at the control entity, status information of the device and obtain a second set of data from a second stack layer. The device is also operative to transmit a response message to the second device in response to a transmission triggering event, where the response message comprises both the status information and at least a portion of the second set of data. The response message may be, for example, a concatenation of the status information and a portion of the second set of data. 
     In some embodiments, a device for reporting status in a network is provided. The device includes means to receive, at a control entity of a first stack layer of the device, a first message from a second device that comprises a set of data and an indicator requesting status information. The device also includes means to determine, at the control entity, status information of the device and obtain a second set of data from a second stack layer. The device also includes means to transmit a response message to the second device in response to a transmission triggering event, where the response message comprises both the status information and at least a portion of the second set of data. The response message may be, for example, a concatenation of the status information and a portion of the second set of data. 
     In some embodiments, a computer program product including a non-transitory computer readable medium storing computer instructions for reporting status in a network is provided. The product includes instructions for receiving, at a control entity of a first stack layer of a first device, a first message from a second device that comprises a set of data and an indicator requesting status information. The product also includes instructions for determining, at the control entity, status information of the first device and obtaining a second set of data from a second stack layer of the first device. The product also includes instructions for transmitting, from the control entity, a response message to the second device in response to a transmission triggering event, where the response message comprises both the status information and at least a portion of the second set of data. The response message may be, for example, a concatenation of the status information and a portion of the second set of data. 
     According to some embodiments, the triggering and transmission of status reporting is delayed from the time of poll reception such that it occurs in coordination with the response to a request message contained in a higher layer&#39;s payload in the received message tagged with the poll. Further, techniques may include delaying the status reporting based on a timer which is started or restarted at the reception of the poll. Further, techniques may include delaying the status reporting until the arrival of a subsequent message in the reverse direction and having the status reporting concur with that message. Delaying the status reporting may be based on the reception of a special-purpose poll bit. Alternatively, delaying the status reporting may be accomplished by delaying the poll to be sent. Delaying the status reporting by delaying the poll may be based on a timer that is started (or restarted) at the transmission of the PDU that contains the request. Further, techniques may include delaying the status reporting by delaying the poll until the arrival of a subsequent message in the forward direction, and having the delayed poll concur with that message. 
     In some embodiments, a method for polling in a network is provided that comprises transmitting, from a control entity of a first device to a second device, a first data message comprising a first set of data. The method further comprises initiating a timer in response to the transmitting of the first data message, and after an expiration or specified time lapse of the timer, transmitting a polling request to the second device, where the polling request is included in an Acknowledged Mode Data (AMD) Protocol Data Unit (PDU), or PDU segment, or polling request PDU. The method also includes receiving, at the control entity from the second device, a response message comprising a concatenation of a second set of data responsive to the first set of data and status information of the second device. 
     In some embodiments, a method for requesting status in a network is provided. The method comprises obtaining, at a control entity of a first device, a first set of data and transmitting, from the control entity to a second device, a first message comprising the first set of data and a status request. The method also includes receiving, at the control entity from the second device, a response message comprising a concatenation of a second set of data responsive to the first set of data and status information of the second device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments of the present disclosure and, together with the description, further serve to explain the principles of the disclosure and to enable a person skilled in the pertinent art to make and use the embodiments disclosed herein. In the drawings, like reference numbers indicate identical or functionally similar elements. 
         FIG. 1  is an illustration of a wireless communication system in accordance with exemplary embodiments. 
         FIG. 2A  is an illustration of an exemplary control plane stack. 
         FIG. 2B  is an illustration of an exemplary user plane stack. 
         FIG. 3  is an exemplary request-response transmission sequence diagram. 
         FIGS. 4A-4C  illustrate data formats in accordance with exemplary embodiments. 
         FIG. 5  is a flow chart illustrating a process in accordance with exemplary embodiments. 
         FIG. 6  is a flow chart illustrating a process in accordance with exemplary embodiments. 
         FIG. 7  is a request-response transmission sequence diagram in accordance with exemplary embodiments. 
         FIG. 8  is a flow chart illustrating a process in accordance with exemplary embodiments. 
         FIG. 9  is a flow chart illustrating a process in accordance with exemplary embodiments. 
         FIG. 10  is a block diagram of an access node in accordance with exemplary embodiments. 
         FIG. 11  is a block diagram of a wireless device in accordance with exemplary embodiments. 
         FIG. 12  is a block diagram of a control node in accordance with exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Particular embodiments are directed to methods, devices, and computer program products for polling and status reporting techniques that avoid redundant accesses by network devices to report status and response messages separately for different protocol layers, thereby reducing network load and improving power efficiency. The disclosed techniques may be applicable, for instance, to delay status reporting from a wireless communication device (WCD), as well as a network or control node. 
     Referring to  FIG. 1 , a wireless communication deployment  100  in accordance with exemplary embodiments includes an access node  104  serving a wireless communication device (WCD)  106 . Examples of WCDs include, but are not limited to, mobile telephones, user equipments (UEs), personal digital assistants, electronic readers, portable electronic tablets, wireless sensors, machine communication devices, personal computers, and laptop computers. Access node  104  may be, for example, a base station, an eNodeB, relay node, or gateway type device, and is capable of communicating with device  106 , along with any additional elements suitable to support wireless communication between wireless communication devices or between a wireless communication device and another communication device, such as landline telephone. The access node  104  may be in communication with, for instance via a network  102 , one or more control nodes  108 , such as a Radio Network Controller (RNC), a Mobility Management Entity (MME), a Mobile Switching Center (MSC) or Base Station Subsystem (BSS). Although node  108  is explicitly identified as a control node, each of nodes  104 ,  106 , and  108  may be understood as a “control” node to the extent that it includes a control unit or otherwise implements control functions. 
       FIGS. 2A and 2B  illustrate stacks for the control plane and user plane respectively.  FIG. 2A  illustrates an exemplary control plane stack  200  of a UE, eNB, and MME. These devices could correspond, for instance, to the WCD  106 , access node  104 , and control node  108  shown in  FIG. 1 .  FIG. 2B  illustrates an exemplary user plane stack  250  for the UE  106  and eNodeB  104 . Signaling, such as data and other messages, may be communicated between layers of the stacks, and between stack entities of peer devices. For instance, PDUs may be communicated between the same layer of different devices, while Service Data Units (SDUs) may be communicated between different layers of the same device. For instance, a PDU may be transmitted from the RLC entity  202  of the eNodeB  104  to the RLC entity  204  of the UE  106  as shown in  FIG. 2A , while an SDU could be obtained by the RLC entity  204  of the UE  106  from a higher layer, such as the RRC layer  206 . 
       FIG. 3  is a two-layered request-response transmission sequence diagram  300  illustrating communications involving an RRC and RLC entity according to present techniques. In this example, a first device  302  and a second device  304  are in communication. Device  302  may be, for example, an access node  104  such as an eNodeB, while device  304  may be a WCD  106 , such as a UE. In this example, each device  302 , 304  includes an RRC, RLC, and MAC layer. At sequence  306 , device  304  receives an RLC transmission that includes data and a request for status information (“poll”). At sequence  308 , the device  304  RLC responds to device  302  with its status, without introducing a delay and using the MAC layer for adaption. At sequence  310 , the RRC layer responds to peer device  302 , using the RLC layer for delivery. At sequence  312 , the RLC delivers the data response, using the MAC for adaption. In comparison to the embodiments disclosed herein, sequence  300  includes an inefficient use of resources by having a redundant RLC transmission back to device  302  in order to report status. 
     The 3GPP 36.322 RLC AM provides information regarding, inter alia, RLC entities, RLC data PDUs, and AMD PDUs. For instance, an AMD PDU may be used to transfer upper layer data by an AM RLC entity. It is used when the AM RLC entity transmits the upper layer PDUs for the first time, or when the AM RLC entity retransmits an AMD PDU without having to perform re-segmentation. Presently, the AMD PDU used by 3GPP LTE consists of a Data field and an AMD PDU header, as illustrated in  FIG. 4A . 3GPP 36.322 also lists additional formats for the AMD PDU, with for instance, an LI field. 
     The specification also describes an AMD PDU segment, often referred to as RESEG PDU, which is used to transfer upper layer data by an AM RLC entity. It is used when the AM RLC entity needs to retransmit a portion or “segment” of an AMD PDU. Like the AMD PDU, the AMD PDU segment has a Data field and an AMD PDU segment header, as illustrated in  FIG. 4B . Again, 3GPP 36.322 lists additional formats for the AMD PDU segment, with for instance, and LI field. 
     The 3GPP 36.322 also provides for a PDU header, for instance, as shown in  FIG. 4A .  FIG. 4A  illustrates an exemplary AMD PDU format  400  in accordance with the specification, while  FIG. 4B  illustrates an exemplary AMD PDU segment format  410 , and  FIG. 4C  illustrates an exemplary Status PDU format  420 . The header of an AMD PDU consists of a “fixed” part  402 , i.e., the fields that are present for every AMD PDU, and an “extension” part—the fields that are absent when not necessary (not shown). The fixed part of the AMD PDU header is byte aligned and consists of a D/C, an RF, a P, an FI, an E and an SN field. The extension part of the AMD PDU header is byte aligned and may consist of, for instance, E(s), LI(s), and occasionally “padding.” The extension part may be used when successive upper layer PDUs or parts of such PDUs are concatenated. 
     Similarly, as illustrated in  FIG. 4B , the header of an AMD PDU segment has a fixed part  412  and a possible extension part (not shown). The first two bytes of the header are structured in the same way as the header of an AMD PDU. The next two bytes of the fixed part are byte aligned and consist of Last Segment Flag (LSF) and Segmentation Offset (SO). The extension part of the AMD PDU segment header is structured in the same way as the extension part of AMD PDU header, and may consist of, for instance, E(s), LI(s), and occasionally padding. The extension part is used to retransmit different data parts that were originally transmitted in one, and the same, AMD PDU. 
     An RLC control PDU may be used by the AM RLC entity to further control the ARQ procedure for control beyond what is possible from using the header fields in the RLC data PDUs. There are three ARQ procedures: Retransmission, Polling, and Status Reporting. The 3GPP LTE standard currently specifies just one RLC control PDU, the STATUS PDU. The STATUS PDU is used for status reporting. It is sent by the receiving side of an AM RLC entity to inform the peer AM RLC entity about AMD PDUs that have been received successfully, and AMD PDUs for which parts are detected as missing. 
     As illustrated in  FIG. 4C , the header of a RLC Control PDU begins with half a byte of data  422  that is present for every RLC control PDU, consisting of a D/C and a Control Protocol Data Unit Type (CPT) field. In the case of a STATUS PDU, two further fixed fields  424  follow: ACK_SN and E1. The extension part  426  of the STATUS PDU (absent when not necessary) consists of reoccurring triplets NACK_SN, E1 and E2, each followed by a pair of SOstart and SOend (absent when not necessary). The D/C value is 0 for an RLC control PDU, as opposed to the value 1, which implicate a Data PDU. The CPT value for STATUS is 000. The values 001-111 are reserved for future use. 
     3GPP 36.322 also describes the concatenation of PDUs The transmitting side of an AM RLC entity will not segment an RLC SDU (or partially transmitted SDU or retransmitted RLC PDU) if the whole SDU (or partially transmitted SDU or retransmitted RLC PDU) fits into the resources provided by the lower adaption and physical transmission layers. It will always maximize the size of any segment to fill the grant to the extent possible. 
     Although the 3GPP specification provides numerous transmission formats and timers, such as the status prohibit timer and reordering timer, there are presently no other mechanisms that inhibit the status transmission in the RLC receive. Aspects of the present disclosure provide devices and techniques for delaying reporting status to avoid redundant transmissions and optimize power consumption. It is particularly beneficial in the above-described scenarios to hold back the status transmission even when the status prohibit timer is not running, or when the reordering timer expires, where request-respond behavior is typical for several layers, thereby forming overlaid request-respond behaviors. 
     Referring to now to  FIG. 5 , a process  500  for reporting status in a network is illustrated. The process  500  may be performed, for instance, by a component of a wireless communication device, access node, or control node. For instance, the process  500  may be performed by a control entity of wireless communication device  106 , access node  104 , or control node  108 . 
     In step  510 , an initial message is received on a first stack layer that comprises a first set of data and data indicating a request for status information. The initial message may be received in a control entity of the first stack layer in a first device, from a second device. For instance, the first stack layer may be a Radio Link Control (RLC) layer. According to some embodiments, the first device may be a WCD, such as a UE, while the second device is a base station, such as an eNodeB. 
     In step  520 , status information is determined. For instance, the control entity may determine the status of the first device. Status information may include, for example, either a positive or a negative acknowledgement of the receipt of a message, such as for the RLC data PDU with a certain sequence number. In some embodiments, the indicator requesting status information in step  510  may be comprised of a polling bit. The polling bit may be a part of an Acknowledged Mode Data (AMD) PDU or PDU segment. According to certain aspects, in response to the polling bit, the determination of status in step  520  may be performed only after a specified delay. 
     In step  530 , a second set of data is obtained from a second stack layer, for instance, a second stack layer of the first device. According to some embodiments, the second stack layer may be the Radio Resource Control (RRC) layer. The second set of data may be obtained in a Service Data Unit (SDU) from the second stack layer, and in certain aspects, may be responsive to the first set of data received in step  510 . 
     In step  540 , a response message is transmitted to the second device. The response message may be, for instance, comprised of some or all of the status information determined in step  520  as well as at least a portion of the second set of data. The response message may be, for example, a concatenation of the status information and at least a portion of the second set of data. The response message may be a Protocol Data Unit (PDU) or PDU segment, such as an Acknowledged Mode Data (AMD) PDU. The transmitting step may include, for example, adaptation on a Medium Access Control (MAC) layer of the device. 
     According to some embodiments, the transmission of step  540  is in response to a transmission triggering event. The triggering event may be, for example, the expiration or specified time lapse of a timer. The timer that causes the triggering even may be started, or reset, in response to receiving the first message of step  510 . In certain aspects, the timer may be a timer that currently exists in the LTE standards, such as the status prohibit timer or a reordering timer. Alternatively, the timer may be a timer specifically configured to delay reporting, i.e., a status reporting delay timer. The status reporting delay timer may be used to delay one or more of status determination and transmission. 
     In some embodiments, the device may be configured such that reception of a poll bit causes the device to check, or otherwise determine, whether a pre-defined existing timer, e.g., the status prohibit or reordering timer, is already running prior to triggering the status. According to certain aspects, if the timer is not yet running, the timer is started, and the status is triggered after the timer has expired, or a predetermined amount of time has elapsed from the existing time. If the timer is already running, it may be restarted in order to provide the necessary delay. In this configuration, a new use of existing timers causes the status transmission triggered by the poll reception to be delayed by the length, or a portion of the length, of the chosen timer. 
     One of ordinary skill in the art will recognize that there are multiple ways to implement the existing timers in order to achieve the desired reporting delay. For instance, one option is that the standardized behavior is changed without concern for type of bearer, i.e., that the existing status prohibit timer is started/restarted at the reception of a poll, instead of when sending a status as in the legacy system. Another option, is to define a differentiated behavior per bearer, e.g., to change the standardized behavior only for Signaling Radio Bearers (SRBs). 
     Yet another alternative option is to add a configuration option to RRC signaling that may be used by an access node, such as an eNodeB, to control the reporting behavior of a WCD. The configuration could be applicable for all bearers, or for certain types of bearer, e.g., SRBs or SRB 1  in LTE, or there could be a separate configuration per each bearer. According to some embodiments, a default configuration has this functionality turned off. 
     In certain aspects, in order to effectively delay reporting to achieve conservation of resources, the timer should be large enough to effectively delay the status so that it coincides with the higher layer response, such as the second set of data received from the second stack layer in step  530 . Values from the standardized range of the timer t-StatusProhibit are non-limiting exemplary values. As outlined in 3GPP TS 36.331, these values may range from between 0 ms and 500 ms, in increments of 5 ms to 50 ms. The standard also provides for spare values. 
     In some embodiments, process  500  does not include the use of an existing 3GPP timer to delay reporting, rather, a new timer, referred to herein as a status reporting delay timer, is defined for delaying status triggering upon reception of a poll. This new timer may be signaled with RRC configuration and may be applicable to all bearers, or for certain types of bearer, e.g., SRBs or SRB1, or there could be a separate configuration per each bearer. In some instances, exemplary values for the new timer may range between 0 ms and 500 ms. 
     According to some embodiments, status triggering and transmission is delayed by introducing a new special-purpose poll bit into the RLC PDU or PDU segment header. When this new kind of delay poll bit is received, for instance, by a WCD in a message from a base station, the status reporting is only triggered after either a pre-defined (specified) or a configured delay. The poll bit may be sent in an RLC control PDU by using a new Control Protocol Data Unit Type (CPT). As illustrated, for instance, by the STATUS message of  FIG. 4C , an RLC control PDU header consists of a D/C and a CPT field. The D/C value is 0 for RLC control PDU. The CPT value would be any value in the range 001-111 that is presently reserved according to the 3GPP specification. 
     According to some embodiments, the delayed actions upon receiving a poll are controlled by the transmitting aspects of the same RLC entity. This is in contrast to the triggering and transmission of status controlled by timers related to the receiving side of that RLC entity. The transmitting side delays the status reporting until forming and transmitting some subsequent (and new) AMD PDU or AMD PDU segment. In this case, the status is triggered upon assembly of a new AMD PDU. This will cause the status transmission triggered by the poll reception to be delayed until the next AMD PDU transmission. When these messages are concatenated, physical layer resources are saved as there are less transmitted bits and triggered random access procedures. 
     According to some embodiments, a new poll bit is introduced in the AMD PDU (or AMD PDU segment). This new poll bit enables different types of status reporting schemes to be used in different scenarios. Additionally, to handle cases where a response message is not sent, a maximum wait time may be defined, after which the status transmission is triggered regardless of AMD PDU transmission. This functionality may be incorporated into the triggering schemes discussed above. 
     For instance, according to a non-limiting example, the network may include a new poll bit in the AMD PDU including RRCConnectionReconfiguration. In this example, the receiver side (a UE in this case) triggers status reporting, but delays it until the next transmission. According to this scenario, the next transmission would likely be RRCConnectionReconfigurationComplete. In some embodiments, when this message is transmitted, the corresponding AMD PDU is concatenated with the status PDU. 
     Referring now to  FIG. 6 , a process  600  for reporting status in a network is illustrated. The process  600  may be performed, for instance, by a component of a wireless communication device, access node, or control node. For instance, the process  600  may be performed by a control entity of wireless communication device  106 , access node  104 , or control node  108 . 
     In step  610 , an RLC entity of a first device, such as WCD  106 , receives a PDU message (or segment) from a peer device, such as access node  104  or control node  108 , that includes data and a poll request. 
     In step  620 , a status of the first device is determined. 
     In step  630 , the RLC entity receives an SDU from the RRC layer of the first device that includes data that is responsive to the data received in the PDU from the peer device. For example, the PDU of step  610  may include two parts: (1) an indicator requesting status information; and (2) a set of data that can be decoded as an RRC message by the higher level stack layers. In this example, the responsive data may be responsive to the decoded RRC message. 
     In step  640 , the first device delivers to the peer device an indication of its status along with the responsive data, for example, using the MAC layer for adaption. The response may also include a polling request. 
     Certain aspects of processes  500  and  600  may be understood with respect to the request-response transmission sequence diagram of  FIG. 7 . Request-response transmission sequence diagram  700  illustrates communications involving an RRC and RLC according to techniques disclosed herein. In this example, a first device  702  and a second device  704  are in communication. Device  702  may be, for example, an access node  104  such as an eNodeB, while device  704  may be a WCD  106 , such as a UE. In this example, each device  702 , 704  includes an RRC, RLC, and MAC layer. At sequence  706 , device  704  receives an RLC transmission that includes data and a request for status information (“poll”). At sequence  708 , device  704  determines status information, but does not respond to device  702  with the status; rather, a delay is introduced and the reporting is effectively “leashed.” At sequence  710 , the RRC layer responds to peer device  702 , using the RLC layer for delivery. The status is then “unleashed,” such that it may be reported back to device  702 . At sequence  712 , the RLC delivers the data response together with the status, using the MAC for adaption. When compared to sequence  300 , which uses existing techniques, sequence  700  improves the efficient use of resources by eliminating the redundant RLC transmission  308  back to device  302  to report status. The data response and the status may be, for instance, concatenated together for transmission in sequence  712 . 
     Certain aspects of disclosed embodiments may be implemented from the status-requesting side of the request-response model. Referring now to  FIG. 8 , a process  800  for requesting status information in a network is illustrated. The process  800  may be performed, for instance, by a component of a wireless communication device, access node, or control node. For instance, the process  800  may be performed by a control entity of wireless communication device  106 , access node  104 , or control node  108 . 
     In step  810 , a control entity of a first device obtains a first set of data. The data may be obtained, for instance, by receiving it from another entity or device, or alternatively, the data may be determined or otherwise developed by the control entity. 
     In step  820 , the control entity transmits the data to a second device, along with a polling request. The message may be communicated, for instance, on the RLC layer. In some embodiments, the message may be a PDU or PDU segment that includes an indicator request status, where the data may be decoded in a higher layer of the second device as an RRC message. 
     In step  830 , the control entity of the first device receives a responsive message from the second device that is a concatenation of a second set of data, which is responsive to the first set of data, and an indication of the second device&#39;s status. 
     According to some embodiments, a delay in status reporting may be accomplished by omitting or delaying the corresponding request for status information. For instance, the transmitting peer device may separate a poll from the message, such as a PDU or PDU segment, that would normally contain the poll and that contains the higher layer data/request. The poll may then be sent in a subsequent message, such as a subsequent PDU or PDU segment. One of ordinary skill in the art will recognize that there are a number of subsequent PDUs that could carry the delayed poll. For instance, it may be transmitted according to the typical manner of selecting a PDU for polling, as outlined in Section 4.1.2.2 of 3GPP 36.322, e.g., by selecting the next new AMD PDU or AMD PDU segment that will be formed from the higher layer input the next RESEG PDU that will be formed from “Last Data Poll” trigger. Alternatively, the message to carry the delayed poll may be configured as a minimal, special-purpose standalone Control PDU, tailored specifically to carry a delayed poll. The time instant to send a message that carries the delayed poll may be triggered by a timer, such as a timer present in the current 3GPP specification, or a timer specifically developed for triggering a delayed request for status information. 
     Referring now to  FIG. 9 , a process  900  for requesting status information in a network is illustrated. The process  900  may be performed, for instance, by a component of a wireless communication device, access node, or control node. For instance, the process  900  may be performed by a control entity of wireless communication device  106 , access node  104 , or control node  108 . 
     In step  910 , an initial data message comprising a first set of data is transmitted from a first device to second device. For instance, the message may be transmitted from an eNodeB to a UE. 
     In step  920 , a timer is initiated in response to the transmission of the initial data message. 
     In step  930 , a polling request is transmitted to a second device, for instance, in an AMD PDU, an AMD PDU segment, or a polling request PDU. The timing of the transmission of the polling request may be based on the timer of step  920 . For instance, the expiration or specified time lapse of the timer may trigger the polling request transmission in step  930 . 
     In step  940 , a response message is received from the second device that is a concatenation of a second set of data, responsive to the first set of data, and an indication of the second device&#39;s status. 
       FIG. 10  illustrates a block diagram of an exemplary access node, such as node  104  shown in  FIG. 1 . As shown in  FIG. 10 , the access node  104  may include: a data processing system  1002 , which may include one or more microprocessors and/or one or more circuits, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like; a network interface  1010 ; a transceiver  1004 , and a data storage system  1006 , which may include one or more non-volatile storage devices and/or one or more volatile storage devices (e.g., random access memory (RAM)). According to some embodiments, the data processing system  1002  may comprise a control unit used for selection of transmission parameters. 
     In embodiments where data processing system  1002  includes a microprocessor, computer readable program code (CRPC)  1008  may be stored in a computer readable medium, such as, but not limited, to magnetic media (e.g., a hard disk), optical media (e.g., a DVD), memory devices (e.g., random access memory), and the like. In some embodiments, computer readable program code is configured such that when executed by a processor, the code causes the data processing system  1002  to perform steps described above (e.g., steps described above with reference to the flow charts shown in  FIGS. 5-6 and 8-9 ). In other embodiments, the access node  104  is configured to perform steps described herein without the need for code. That is, for example, data processing system  1002  may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and/or software. For example, in particular embodiments, the functional components of the base station described above may be implemented by data processing system  1002  executing computer instructions, by data processing system  1002  operating independent of any computer instructions, or by any suitable combination of hardware and/or software. 
       FIG. 11  illustrates a block diagram of an exemplary wireless device, such as device  106  shown in  FIG. 1 . As shown in  FIG. 11 , the device  106  may include: a data processing system  1102 , which may include one or more microprocessors and/or one or more circuits, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like; a transceiver  1104 , and a data storage system  1106 , which may include one or more non-volatile storage devices and/or one or more volatile storage devices (e.g., random access memory (RAM)). According to some embodiments, the data processing system  1102  may comprise a control unit used for selection of transmission parameters. 
     In embodiments where data processing system  1102  includes a microprocessor, computer readable program code (CRPC)  1108  may be stored in a computer readable medium, such as, but not limited, to magnetic media (e.g., a hard disk), optical media (e.g., a DVD), memory devices (e.g., random access memory), and the like. In some embodiments, computer readable program code is configured such that when executed by a processor, the code causes the data processing system  1102  to perform steps described above (e.g., steps described above with reference to the flow charts shown in  FIGS. 5-6 and 8-9 ). In other embodiments, the device  106  is configured to perform steps described herein without the need for code. That is, for example, data processing system  1102  may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and/or software. For example, in particular embodiments, the functional components of the base station described above may be implemented by data processing system  1102  executing computer instructions, by data processing system  1102  operating independent of any computer instructions, or by any suitable combination of hardware and/or software. 
       FIG. 12  illustrates a block diagram of an exemplary control node, such as node  108  shown in  FIG. 1 . As shown in  FIG. 12 , the control node  108  may include: a data processing system  1202 , which may include one or more microprocessors and/or one or more circuits, such as an application specific integrated circuit (ASIC), field-programmable gate arrays (FPGAs), and the like; a network interface  1206 , and a data storage system  1204 , which may include one or more non-volatile storage devices and/or one or more volatile storage devices (e.g., random access memory (RAM)). According to some embodiments, the data processing system  1202  may comprise a control unit used for selection of transmission parameters. 
     In embodiments where data processing system  1202  includes a microprocessor, computer readable program code (CRPC)  1208  may be stored in a computer readable medium, such as, but not limited, to magnetic media (e.g., a hard disk), optical media (e.g., a DVD), memory devices (e.g., random access memory), and the like. In some embodiments, computer readable program code is configured such that when executed by a processor, the code causes the data processing system  1202  to perform steps described above (e.g., steps described above with reference to the flow charts shown in  FIGS. 5-6 and 8-9 ). In other embodiments, the control node  104  is configured to perform steps described herein without the need for code. That is, for example, data processing system  1202  may consist merely of one or more ASICs. Hence, the features of the embodiments described herein may be implemented in hardware and/or software. For example, in particular embodiments, the functional components of the base station described above may be implemented by data processing system  1202  executing computer instructions, by data processing system  1202  operating independent of any computer instructions, or by any suitable combination of hardware and/or software. 
     While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Thus, the breadth and scope of the present disclosure should not limited by any of the above-described exemplary embodiments. For example, while much of the disclosure has been described with respect to terms and concepts applicable to s system based on the 3GPP LTE FDD technology, one of ordinary skill in the art will readily recognize the disclosed methods, devices, and computer program products are applicable to other communication systems, such as any system using overlaid control procedures of a request-response type. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context. 
     Additionally, while the processes described above and illustrated in the drawings are shown as a sequence of steps, this was done solely for the sake of illustration. Accordingly, it is contemplated that some steps may be added, some steps may be omitted, the order of the steps may be re-arranged, and some steps may be performed in parallel.