Patent Application
20170012751
The present invention relates generally to managing the allocation of resources in a network, and in particular embodiments, to techniques and mechanisms for multipoint Radio Link Control (RLC) coordinator for loosely coordinated multipoint communications.
Traditionally, radio access links between access points (APs) and mobile devices have been the bottleneck that constrains throughput between the mobile devices and the core network, as data rates over backhaul network connection between the radio access network (RAN) and the core network are typically many times faster than data rates over the corresponding wireless access links. However, next-generation network architectures having densely deployed cells may achieve significant increases in throughput, as well as share backhaul network resources amongst greater numbers of APs. As a result, the capacity gap between radio access links and backhaul network connection may be reduced in some next-generation network implementations, resulting in situations where data forwarding rates are constrained by the backhaul network connection, rather than the radio access link. Accordingly, techniques for efficiently utilizing backhaul resources in next-generation densely-deployed networks are desired.
Technical advantages are generally achieved by embodiments of this disclosure which describe multipoint RLC coordinator for loosely coordinated multipoint communications
In accordance with an embodiment, a method for efficiently utilizing backhaul resources during multipoint reception is provided. In this example, the method includes identifying access points receiving a wireless transmission in accordance with a multipoint reception scheme. Lower-layer decoding of the wireless transmissions is performed by the access points to obtain transport blocks carried by the wireless transmission. Radio link control (RLC) layer decoding of the transport blocks is performed at a network node to obtain data packets carried by the wireless transmission. The method further includes scheduling the transport blocks to be communicated from the access points over backhaul links to the network node. An apparatus for performing this method is also provided.
In accordance with another embodiment, a method for efficiently utilizing backhaul resources is provided. In this example, the method includes receiving a wireless transmission from a user equipment at an access point, and performing lower layer decoding on the wireless transmission to obtain transport blocks carried by the wireless transmission. The method further includes receiving a scheduling instruction for communicating the transport blocks over a backhaul link, and communicating the transport blocks over the backhaul link in accordance with the scheduling instruction. Radio link control (RLC) layer decoding of the transport blocks is performed at a network node to obtain data packets carried by the wireless transmission. An apparatus for performing this method is also provided.
In accordance with yet another embodiment, a method for coordinating access to limited backhaul resources is provided. In this example, the method includes identifying access points in a wireless network. The access points perform lower-layer decoding on wireless transmissions to obtain at least a first set of transport blocks and a second set of transport blocks carried by the wireless transmissions. Radio link control (RLC) layer decoding of the first set of transport blocks is performed at a first network node, and RLC layer decoding of the second set of transport blocks is performed at a second network node. The method further includes scheduling a shared backhaul link to carry transport blocks destined for the first network node or the second network node, wherein the shared backhaul link is capable of carrying transport blocks in the first set of transport blocks at least partially to the first network node and carrying transport blocks in the second set of transport blocks at least partially to the second network node. An apparatus for performing this method is also provided.
For a more complete understanding of the present disclosure, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.
The making and using of embodiments of this disclosure are discussed in detail below. It should be appreciated, however, that the concepts disclosed herein can be embodied in a wide variety of specific contexts, and that the specific embodiments discussed herein are merely illustrative and do not serve to limit the scope of the claims. Further, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of this disclosure as defined by the appended claims. As used herein, the term “transport block” refers to payload data, or copies of payload data (e.g., replicating decoded data stored in a buffer), carried over the physical layer of a wireless network. For example, in a long term evolution (LTE) network, a transport block refers to a media access control (MAC) protocol data unit (PDU), or a copy of a MAC PDU, carried in the physical downlink shared channel (PDSCH) and/or physical uplink shared channel (PUSCH).
In conventional networks, access points communicate uplink data over dedicated backhaul resources as soon as the uplink transmissions are received over the access network. This is possible because conventional networks typically have significantly more available resources in the backhaul network than the access network. Next-generation densely-deployed networks may not have such an abundancy of available backhaul resources due to higher data rates over the access network as well as due to the sharing of backhaul resources amongst greater numbers of access points. Consequently, the opportunistic use of backhaul resources may reduce efficiency and/or performance in next-generation densely-deployed networks. Indeed, the opportunistic use of backhaul resources may be particularly costly for access points participating in multi-point reception, as it may cause the access points to unnecessarily communicate redundant uplink data over the backhaul network. Accordingly, techniques for efficiently utilizing backhaul resources in next-generation densely-deployed networks are desired.
Aspects of this disclosure improve backhaul resource utilization efficiency by performing lower-layer decoding of uplink transmissions at access points to obtain transport blocks (TBs) carried by the uplink transmissions, and then strategically scheduling the TBs over backhaul links extending between the access points and network nodes. Upon reception, the network nodes may perform radio link control (RLC) decoding on the TBs to obtain the uplink data. Performing lower-layer decoding at the access points offers efficiency advantages over conventional techniques that opportunistically communicate the entire uplink media access control (MAC) physical data unit (PDU) over the backhaul network, as the TBs (e.g., radio link control (RLC) PDUs) obtained from the lower layer decoding have less overhead than the MAC PDUs carried by the uplink physical-layer transmissions. Moreover, scheduling the TBs over the backhaul links provides additional efficiency/performance benefits. For example, TBs may be scheduled in a manner that prioritizes time-sensitive data (e.g., voice traffic). As another example, TBs may be scheduled in a manner that strategically routes TBs over backhaul paths in a manner that increases the overall utilization of backhaul resources, e.g., TBs may be re-routed over an alternate path to allow other TBs to be transported over a primary path. Additionally, in the context of multi-point reception, it may be possible to avoid unnecessarily transporting redundant TBs over backhaul links. These and other aspects are described in greater detail below.
In this example, the APs 230, 240 are configured to receive a wireless transmission 215 from the mobile device 210 in accordance with a multi-point reception scheme. The APs 230, 240 perform lower layer decoding on the wireless transmission 215 to obtain TBs carried by the wireless transmission 215. The APs 230, 240 communicate the TBs over the backhaul paths 235, 245 to the network node 260, which performs RLC decoding on the TBs to obtain uplink data. Notably, TBs (e.g., MAC PDUs) may carry radio link control (RLC) physical data units (PDUs). Accordingly, the network node 260 may decode the TBs to obtain RLC PDUs.
The network node 260 may schedule TBs to be communicated over the backhaul paths 235, 245 by sending periodic and/or aperiodic control signaling the APs 230, 240. In one embodiment, the network node 260 sends a “send” instruction to at least one of the APs 230, 240. The send instruction instructs the recipient AP to send one or more TBs over one of the backhaul paths. The send instruction may identify a particular TB or group of TBs. In one example, the send instruction identifies a particular data stream associated with a group of TBs. For instance, each data stream may be associated with a different hybrid automatic repeat request (HARQ) process, and the send instruction may specify an identifier associated with a given HARQ process to identify the corresponding data stream. In such an example, the send instruction may instruct the recipient AP to send all TBs (e.g., all buffered and future TBs) associated with the identified data stream over the backhaul path. Alternatively, the send instruction may instruct the recipient AP to send a specific TB (e.g., TB X) or a specific subset of TBs (e.g., TBs X, Y, and Z) in the identified data stream over the backhaul path. As yet another alternative, the send instruction may instruct the recipient AP to send TBs up until a certain TB (or bit) in the identified data stream over the backhaul path, e.g., send TBs preceding TB Y in the data stream, send TBs between TB X and TB Z in the data stream. In another example, the send instruction may instruct the recipient AP to send all buffered and/or future TBs (e.g., for all data streams) over the backhaul path.
In another embodiment, the network node 260 sends a “hold” instruction to at least one of the APs 230, 240. The hold instruction may instruct the recipient AP to buffer or hold a particular TB or group of TBs for a period without sending the TB or group of TBs over a backhaul pathway. In some embodiments, the period is a defined period specified by the hold instruction. In other embodiments, the period is an indefinite period, e.g., the hold instruction instructs the recipient AP to buffer all TBs until further notice is provided by the network node. In yet another embodiment, the network node 260 sends a “discard” instruction to at least one of the APs 230, 240. The discard instruction may instruct the recipient AP to discard/drop all TBs (e.g., all buffered and future TBs) associated with a particular data stream (e.g., HARQ process), to discard/drop a specific TB (e.g., TB X) or a specific subset of TBs (e.g., TBs X, Y, and Z) associated with a particular data stream, or to discard/drop TBs up until a certain TB (or bit) in the particular data stream, e.g., TBs preceding TB Y in the data stream.
In some embodiments, the controller 290 may schedule TBs to be communicated over the backhaul paths 235, 245. The controller 290 may be any network device adapted to make scheduling decisions, such as a scheduler, a traffic engineering (TE) controller, or a software defined network (SDN) controller.
Embodiments may also strategically schedule TBs obtained from wireless transmissions communicated by different mobile devices over backhaul resources.
In some embodiments, the network node 260 or the controller 290 schedules TBs over one or more backhaul links 203, 204, 205 indirectly by communicating policy instructions to the access points 230, 240 and/or the intermediate node 250. The policy instructions may govern how TBs are handled. For example, the policy instructions may specify when, and/or under what conditions a TB is to be forwarded over one of the backhaul links 203, 204, 205. Notably, different policies may govern the forwarding of different TBs within the same traffic flow. As another example, the policy instructions may specify how long the TBs are to be buffered prior to being forwarded over one of the backhaul links 203, 204, 205, as well as when, and/or under what conditions, the TB is to be discarded. The policy instructions may also specify different treatments for TBs having different priorities. The policy instructions may be communicated to the access points 230, 240 and/or the intermediate node 250 prior to reception of the TBs. For example, the policy instructions may be communicated to the access points 230, 240 prior to communication of the wireless transmissions 215, 216, 226, or even before the mobile devices 210, 220 enter the network.
In one embodiment, a policy instruction instructs an access point, or an intermediate node, to send, drop, or buffer a TB when one or more criteria are satisfied. The one or more criteria may correspond to characteristics associated with the individual transport block and/or the traffic flow in general (e.g., priority, size, staleness), conditions of a backhaul link (e.g., congestion), conditions of a wireless link, or combinations thereof. In one example, the policy instruction instructs the intermediate node or the access point to transmit TBs over a backhaul link when the TBs are associated with a priority level that exceeds a threshold. In another example, the policy instruction instructs the intermediate node or access point to buffer or drop TBs that have a priority level that is less than a threshold. Other examples are also possible.
In one embodiment, the network device instructs a first access point to communicate all of the TBs to the network node by scheduling the TBs to be communicated over backhaul links extending between the first access point and the network node. In such an embodiment, the network device may instruct other access points participating in the multipoint reception scheme to buffer decoded TBs for a period, e.g., a defined period, or until further notice. If the network node fails to receive one or more of the TBs, then the network device may instruct one of the access points buffering those TBs to communicate the TBs to the network node via corresponding backhaul links. In other embodiments, the network device instructs multiple access points to communicate TBs to the network node.
Embodiments of this disclosure may strategically schedule shared backhaul links to carry TBs obtained from different wireless transmissions.
The backhaul network 609 includes intermediate nodes 650, 655 positioned in between the network nodes 660, 670 and the APs 630, 640, as well as an intermediate node 651 positioned in between the network nodes 660 and the AP 635, and an intermediate node 652 positioned in between the network nodes 670 and the AP 645. The backhaul network 609 further includes backhaul links 601-607. The AP 635 is interconnected to the network node 660 via a path extending over the backhaul links 601. The AP 645 is interconnected to the network node 670 via a path extending over the backhaul links 602.
The AP 630 is interconnected to the network node 660 via a path extending over the backhaul links 603, 605, 606. The AP 645 is interconnected to the network node 670 via a path extending over the backhaul links 604, 605, 607. The backhaul link 605 is shared between the paths interconnecting the APs 635, 645 to the network nodes 660, 670 (respectively), and is referred to as “the shared backhaul link” 605 throughout this disclosure. In some embodiments, the network nodes 660, 670 will coordinate the scheduling of TBs over the shared backhaul link 605. In other embodiments, the controller 690 will schedule TBs over the shared backhaul link 605.
In some embodiments, the network nodes 660, 670 or the controller 690 schedule TBs over the shared backhaul link 605 indirectly by communicating policy instructions to the access points 630, 640 and/or the intermediate node 650. The policy instructions may specify forwarding instructions for communicating TBs over the shared backhaul link 605, as well as other handling instructions, e.g., how long to buffer a TB, when to drop a TB, when to forward a TB, etc. The policy instructions may also specify handling instructions that are based on the characteristics of the TBs. For example, the policies may specify default handling instructions for TBs associated with a particular device (e.g., mobile devices, gateways) or a particular HARQ process number, or TBs that have been scheduled on specific resources, e.g., resource blocks, transmission time intervals (TTIs). The default handling instructions may specify that the TB is handled in a certain way (buffered/dropped/forwarded) when a condition is satisfied (e.g., after a threshold number of retransmission attempts, for packets having a certain payload size). The default handling instructions may be overridden by a backhaul scheduling order. The policy instructions may be communicated to the access points 630, 640 and/or the intermediate node 650 ahead of time, before the TBs are received at the access points 630, 640 and/or the intermediate node 650.
In some embodiments, all resources of a shared link may be scheduled to carry TBs from a single transmission. In the example depicted by
In other embodiments, resources of a shared link may be scheduled in a shared fashion such that the shared link transports TBs of different wireless transmissions during a common period. In the example depicted by
In some embodiments, the processing system 900 is included in a network device that is accessing, or part otherwise of, a telecommunications network. In one example, the processing system 900 is in a network-side device in a wireless or wireline telecommunications network, such as an access point, a relay station, a scheduler, a controller, a gateway, a router, an applications server, or any other device in the telecommunications network. In other embodiments, the processing system 900 is in a user-side device accessing a wireless or wireline telecommunications network, such as a mobile station, a user equipment (UE), a personal computer (PC), a tablet, a wearable communications device (e.g., a smartwatch), or any other device adapted to access a telecommunications network.
In some embodiments, one or more of the interfaces 910, 912, 914 connects the processing system 900 to a transceiver adapted to transmit and receive signaling over the telecommunications network.
The transceiver 1000 may transmit and receive signaling over any type of communications medium. In some embodiments, the transceiver 1000 transmits and receives signaling over a wireless medium. For example, the transceiver 1000 may be a wireless transceiver adapted to communicate in accordance with a wireless telecommunications protocol, such as a cellular protocol (e.g., long-term evolution (LTE)), a wireless local area network (WLAN) protocol (e.g., Wi-Fi), or any other type of wireless protocol (e.g., Bluetooth, near field communication (NFC)). In such embodiments, the network-side interface 1002 comprises one or more antenna/radiating elements. For example, the network-side interface 1002 may include a single antenna, multiple separate antennas, or a multi-antenna array configured for multi-layer communication, e.g., single input multiple output (SIMO), multiple input single output (MISO), multiple input multiple output (MIMO). In other embodiments, the transceiver 1000 transmits and receives signaling over a wireline medium, e.g., twisted-pair cable, coaxial cable, optical fiber. Specific processing systems and/or transceivers may utilize all of the components shown, or only a subset of the components, and levels of integration may vary from device to device.
Although the description has been described in detail, it should be understood that various changes, substitutions and alterations can be made without departing from the spirit and scope of this disclosure as defined by the appended claims. Moreover, the scope of the disclosure is not intended to be limited to the particular embodiments described herein, as one of ordinary skill in the art will readily appreciate from this disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, may perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
