PATENT DOCUMENT

Publication Number: US-9344225-B2
Application Number: US-201414182075-A
Country: US
Kind Code: B2

Title: Distributed ARQ for wireless communication system

Abstract:
Systems and methods for providing distributed Automatic Repeat Request (ARQ) in a wireless communication system are described herein. In one embodiment, a relay station interconnects a base station of the wireless communication system and one or more mobile stations. A first ARQ process is performed for a first connection between the base station and the relay station. A separate second ARQ process is performed for a second connection between the relay station and a mobile station. In this manner, rather than having end-to-end ARQ between the base station and the mobile station, a distributed ARQ process is provided.

Claims:
What is claimed is: 
     
       1. A mobile station for communicating in a wireless communication network, the mobile station comprising:
 a wireless network interface configured to:
 establish a first connection between a relay station and the mobile station within the wireless communication network, and communicate with the relay station over the first connection, wherein communication between the relay station and a base station is over a second connection established between the base station and the relay station within the wireless communication network; and 
 establish a third connection between a target station and the mobile station within the wireless communication network in response to a handover of the mobile station from the relay station to the target station, wherein, during the handover, context information that enables continuity of data flow for the mobile station at the target station is forwarded by the relay station; and 
 
 a control system comprising a first protocol stack having convergence, media access control (MAC) and physical (PHY) layers, wherein the control system is configured to perform, through the wireless network interface, a first ARQ process over the first connection according to at least the first protocol stack; 
 wherein communication by the relay station over the first connection is further according to a second protocol stack comprised in the relay station and having convergence, media access control (MAC) and physical (PHY) layers. 
 
     
     
       2. The mobile station of  claim 1 , wherein the relay station is one of:
 a mobile relay station; or 
 a fixed relay station. 
 
     
     
       3. The mobile station of  claim 1 , further comprising:
 a user interface interacting with the control system and comprising one or more of:
 a speaker; 
 a microphone; 
 a display; or 
 a keypad. 
 
 
     
     
       4. The mobile station of  claim 1 , wherein a plurality of mobile stations, including the mobile station, are served by the relay station within the wireless communication network;
 wherein the second connection is a transport connection for downlink data for the plurality of mobile stations; and 
 wherein a plurality of connections, including the first connection, to the plurality of mobile stations are maintained by the relay station, each of the plurality of connections being for one of the plurality of mobile stations and at least some of the plurality of connections being ARQ enabled. 
 
     
     
       5. The mobile station of  claim 4 , wherein a separate ARQ process is performed by the relay station for each of the plurality of connections that is ARQ enabled. 
     
     
       6. The mobile station of  claim 1 , wherein the target station is the base station, and wherein the control system is configured to initiate, through the wireless network interface, the handover of the mobile station from the relay station to the base station;
 wherein the context information is communicated to the base station by the relay station for the first ARQ process, responsive to the control system initiating the handover of the mobile station from the relay station to the base station; and 
 wherein the first ARQ process is continued by the base station with the mobile station, responsive to the context information being communicated to the base station for the first ARQ process. 
 
     
     
       7. The mobile station of  claim 1 , wherein the target station is a second relay station that is associated with the base station and operates in an end-to-end ARQ mode, wherein the control system is configured to initiate, through the wireless network interface, the handover of the mobile station from the relay station to the second relay station;
 wherein the context information is communicated to the base station by the relay station for the first ARQ process, responsive to the control system initiating the handover of the mobile station from the relay station to the second relay station; and 
 wherein the first ARQ process with the mobile station is continued by the base station via the second relay station in an end-to-end manner, responsive to the context information being communicated by the relay station to the base station for the first ARQ process. 
 
     
     
       8. The mobile station of  claim 1 , wherein the target station is a second relay station that is associated with the base station and operates in a distributed ARQ mode, wherein the control system is configured to initiate, through the wireless network interface, the handover of the mobile station from the relay station to the second relay station;
 wherein the context information is communicated to the base station by the relay station for the first ARQ process, responsive to the control system initiating the handover of the mobile station from the relay station to the second relay station; 
 wherein the context information is forwarded by the base station to the second relay station for the first ARQ process, responsive to the context information being communicated by the relay station to the base station for the first ARQ process; and 
 wherein the first ARQ process with the mobile station is continued by the second relay station, responsive to the context information being forwarded by the base station to the second relay station for the first ARQ process. 
 
     
     
       9. The mobile station of  claim 1 , wherein the target station is a second base station, wherein the control system is configured to initiate, through the wireless network interface, the handover of the mobile station from the relay station to a second base station;
 wherein the context information is communicated to the base station by the relay station for the first ARQ process, responsive to the control system initiating the handover of the mobile station from the relay station to the second base station; 
 wherein the context information is forwarded by the base station to the second base station for the first ARQ process, responsive to the context information being communicated by the relay station to the base station for the first ARQ process; and 
 wherein the first ARQ process with the mobile station is continued by the second base station, responsive to the context information being forwarded by the base station to the second base station for the first ARQ process. 
 
     
     
       10. The mobile station of  claim 1 , wherein the target station is a second relay station that is associated with a second base station and operates in an end-to-end ARQ mode, wherein the control system is configured to initiate, through the wireless network interface, the handover of the mobile station from the relay station to the second relay station;
 wherein the context information is communicated to the base station by the relay station for the first ARQ process, responsive to the control system initiating the handover of the mobile station from the relay station to the second relay station; 
 wherein the context information is forwarded by the base station to the second base station for the first ARQ process, responsive to the context information being communicated by the relay station to the base station for the first ARQ process; and 
 wherein the first ARQ process with the mobile station is continued by the second base station via the second relay station in an end-to-end manner, responsive to the context information being forwarded by the base station to the second base station for the first ARQ process. 
 
     
     
       11. The mobile station of  claim 1 , wherein the target station is a second relay station that is associated with a second base station and operates in a distributed ARQ mode, wherein the control system is configured to initiate, through the wireless network interface, the handover of the mobile station from the relay station to the second relay station;
 wherein the context information is communicated to the base station by the relay station for the first ARQ process, responsive to the control system initiating the handover of the mobile station from the relay station to the second relay station; 
 wherein the context information is forwarded to the second base station by the base station for the first ARQ process, responsive to the context information being communicated to the base station by the relay station for the first ARQ process; 
 wherein the context information is forwarded to the second relay station by the second base station for the first ARQ process, responsive to the context information being forwarded to the second base station by the base station for the first ARQ process; and 
 wherein the first ARQ process with the mobile station is continued by the second relay station, responsive to the context information being forwarded to the second relay station by the second base station for the first ARQ process. 
 
     
     
       12. A relay station associated with a base station in a wireless communication network, the relay station comprising:
 wireless interface configured to communicate within the wireless communication network with a base station and one or more mobile stations; and 
 a control system configured to:
 establish a first connection to the base station through the wireless interface according to at least a first protocol stack comprising convergence, media access control (MAC) and physical (PHY) layers; 
 perform a first Automatic Repeat Request (ARQ) process for the first connection between the relay station and the base station through the wireless interface; 
 establish a second connection to a mobile station within a wireless coverage area of the relay station through the wireless interface according to a second a protocol stack comprising convergence, MAC and PHY layers; 
 perform a second ARQ process for the second connection between the relay station and the mobile station through the wireless interface; and 
 
 forward, during a handover of the mobile station from the relay station to a target station, context information associated with at least the second protocol stack to enable continuity of data flow for the mobile station at the target station. 
 
     
     
       13. The relay station of  claim 12 , wherein the relay station is one of:
 a mobile relay station; or 
 a fixed relay station. 
 
     
     
       14. The relay station of  claim 12 , further comprising memory associated with the control system;
 wherein the control system comprises one or more of:
 one or more central processing units executing instructions stored in the memory; 
 one or more application specific integrated circuits; or 
 one or more programmable field arrays. 
 
 
     
     
       15. The relay station of  claim 12 , wherein the relay station is configured to serve a plurality of mobile stations, including the mobile station, within the wireless coverage area of the relay station, and the first connection is a transport connection for downlink data for the plurality of mobile stations;
 wherein the control system is configured to maintain, through the wireless interface, a plurality of second connections, including the second connection, to the plurality of mobile stations, wherein each of the plurality of second connections is for one of the plurality of mobile stations, and wherein at least some of the plurality of second connections are ARQ enabled. 
 
     
     
       16. The relay station of  claim 15 , wherein the control system is configured to maintain, through the wireless interface, a separate ARQ process for each of the plurality of second connections that is ARQ enabled. 
     
     
       17. The relay station of  claim 12 , wherein the target station is the base station, wherein the control system is configured to forward, through the wireless interface, the context information to the base station for the second ARQ process, responsive to initiation of the handover of the mobile station from the relay station to the base station;
 wherein the second ARQ process with the mobile station is continued by the base station, responsive to the control system forwarding the context information to the base station for the second ARQ process. 
 
     
     
       18. The relay station of  claim 12 , wherein the target station is a second relay station that is associated with the base station and operates in an end-to-end ARQ mode, wherein the control system is configured to forward, through the at least one wireless interface, the context information to the base station for the second ARQ process, responsive to initiation of the handover of the mobile station from the relay station to the second relay station;
 wherein the second ARQ process with the mobile station is continued by the base station in an end-to-end manner via the second relay station, responsive to the control system forwarding the context information to the base station for the second ARQ process. 
 
     
     
       19. The relay station of  claim 12 , wherein the target station is a second relay station that is associated with the base station and operates in a distributed ARQ mode, wherein the control system is configured to forward, through the wireless interface, the context information to the base station for the second ARQ process, responsive to initiation of the handover of the mobile station from the relay station to the second relay station;
 wherein the context information is forwarded to the second relay station by the base station for the second ARQ process, responsive to the control system forwarding the context information to the base station for the second ARQ process; and 
 wherein the second ARQ process with the mobile station is continued by the second relay station, responsive to the context information being forwarded by the base station to the second relay station for the second ARQ process. 
 
     
     
       20. The relay station of  claim 12 , wherein the target station is a second base station, wherein the control system is configured to forward, through the wireless interface, the context information to the base station for the second ARQ process, responsive to initiation of the handover of the mobile station from the relay station to the second base station;
 wherein the context information is forwarded to the second base station by the base station for the second ARQ process, responsive to the control system forwarding the context information to the base station for the second ARQ process; and 
 wherein the second ARQ process with the mobile station is continued by the second base station, responsive to the context information being forwarded to the second base station by the base station for the second ARQ process. 
 
     
     
       21. The relay station of  claim 12 , wherein the target station is a second relay station that is associated with a second base station and operates in an end-to-end ARQ mode, wherein the control system is configured to forward, through the wireless interface, the context information to the base station for the second ARQ process, responsive to initiation of the handover of the mobile station from the relay station to the second relay station;
 wherein the context information is forwarded to the second base station by the base station for the second ARQ process, responsive to the control system forwarding the context information to the base station for the second ARQ process; and 
 wherein the second ARQ process with the mobile station is continued by the second base station in an end-to-end manner via the second relay station, responsive to the context information being forwarded by the base station to the second base station for the second ARQ process. 
 
     
     
       22. The relay station of  claim 12 , wherein the target station is a second relay station that is associated with a second base station and operates in a distributed ARQ mode, wherein the control system is configured to forward, through the wireless interface, the context information to the base station for the second ARQ process, responsive to initiation of the handover of the mobile station from the relay station to the second relay station;
 wherein the ARQ context information is forwarded to the second relay station by the base station for the second ARQ process, responsive to the control system forwarding the context information to the base station for the second ARQ process; and 
 wherein the second ARQ process with the mobile station is continued by the second relay station, responsive to the context information being forwarded by the base station to the second relay station for the second ARQ process.

Description:
This application is a continuation of U.S. patent application Ser. No. 12/922,486 filed Oct. 25, 2010, which itself claims benefit of U.S. provisional patent application No. 61/036,828 filed Mar. 14, 2008, the disclosures of both of which are hereby incorporated by reference in their entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The present invention relates to a wireless communication system and more particularly relates to distributed Automatic Repeat Request (ARQ) in a wireless communication system. 
     BACKGROUND 
     A relay station is a device that is used to interconnect a base station and a mobile station in a wireless communication network. By using a relay station, a base station may cover areas that would otherwise be inaccessible to the base station, such as the interior of a shopping center. Automatic Repeat Request (ARQ) is an error control process to achieve reliable data transmission over en unreliable connection. An ARQ process is desired for a wireless communication network having both base stations and relay stations. 
     SUMMARY OF THE DETAILED DESCRIPTION 
     Systems and methods for providing distributed Automatic Repeat Request (ARQ) in a wireless communication system are described herein. In one embodiment, a relay station interconnects a base station of the wireless communication system and one or more mobile stations. A first ARQ process is performed for a first connection between the base station and the relay station. A separate second ARQ process is performed for a second connection between the relay station and a mobile station. In this manner, rather than having end-to-end ARQ between the base station and the mobile station, a distributed ARQ process is provided. 
     In addition, systems and methods for maintaining ARQ continuity during a handover from the relay station to a target station are disclosed herein. In general, when a mobile station initiates a handover from the relay station providing distributed ARQ to a target station, the relay station forwards ARQ context information to the target station for an ARQ enabled connection between the relay station and the mobile station. More specifically, in one embodiment, if the target station is the base station serving the relay station, the relay station forwards the ARQ context information to the base station. Then, by using the ARQ context information, the base station is enabled to continue the ARQ process for the ARQ enabled connection to the mobile station. 
     In another embodiment, if the target station is second relay station served by the base station, the relay station forwards the ARQ context information to the base station. Then, if the second relay station is operating in a distributed ARQ mode or otherwise enabled to provide distributed ARQ, the base station forwards the ARQ context information to the second relay station. By using the ARQ context information, the second relay station is then enabled to continue the ARQ process for the ARQ enabled connection with the mobile station. If the second relay station is not operating in a distributed ARQ mode or otherwise enabled to provide distributed ARQ, the base station is enabled to continue the ARQ process for the ARQ enabled connection with the mobile station via the second relay station in an end-to-end, rather than distributed, manner. 
     In another embodiment, if the target station is a second base station, the relay station forwards the ARQ context information to the base station. The base station then forwards the ARQ context information to the second base station via a backhaul network. Then, by using the ARQ context information, the second base station is enabled to continue the ARQ process for the ARQ enabled connection with the mobile station. 
     In another embodiment, if the target station is a relay station of a second base station, the relay station forwards the ARQ context information to the base station, which in turn forwards the ARQ context information to the second base station. Then, if the second relay station is operating in a distributed ARQ mode or otherwise enabled to provide distributed ARQ, the second base station forwards the ARQ context information to the second relay station. By using the ARQ context information, the second relay station is then enabled to continue the ARQ process for the ARQ enabled connection with the mobile station. If the second relay station is not operating in a distributed ARQ mode or otherwise enabled to provide distributed ARQ, the second base station is enabled to continue the ARQ process for the ARQ enabled connection with the mobile station via the second relay station in an end-to-end, rather than distributed, manner. 
     Those skilled in the art will appreciate the scope of the present invention and realize additional aspects thereof after reading the following detailed description in association with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings incorporated in and forming a part of this specification illustrate several aspects of the invention, and together with the description serve to explain the principles of the invention. 
         FIG. 1  is a block diagram of a wireless communication network including a base station, a relay station, and a number of mobile stations according to one embodiment of this disclosure; 
         FIG. 2  illustrates an end-to-end mode of operation of a relay station according to one embodiment of this disclosure; 
         FIG. 3  illustrates a distributed mode of operation of a relay station according to one embodiment of this disclosure; 
         FIG. 4  illustrates exemplary protocol stacks of a base station, a relay station, and a mobile station when the relay station is operating in a distributed mode according to one embodiment of this disclosure; 
         FIGS. 5A and 5B  illustrate forwarding of Automatic Repeat Request (ARQ) context information from a relay station operating in a distributed mode when a handover of the mobile station from the relay station to a base station associated with the relay station occurs according to one embodiment of this disclosure; 
         FIGS. 6A through 6C  illustrate forwarding of ARQ context information from a relay station operating in a distributed mode when a handover of the mobile station from a relay station to another relay station associated with the same base station occurs according to one embodiment of this disclosure; 
         FIGS. 7A and 7B  illustrate forwarding of ARQ context information from a relay station operating in a distributed mode when a handover of the mobile station from the relay station to a different base station occurs according to one embodiment of this disclosure; 
         FIGS. 8A through 8C  illustrate forwarding of ARQ context information from a relay station operating in a distributed mode when a handover of the mobile station from a relay station to another relay station associated with a different base station occurs according to one embodiment of this disclosure; 
         FIG. 9  is a block diagram of an exemplary embodiment of the base station of  FIG. 1 ; 
         FIG. 10  is a block diagram of an exemplary embodiment of the relay station of  FIG. 1 ; and 
         FIG. 11  is a block diagram of an exemplary embodiment of one of the mobile stations of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the invention and illustrate the best mode of practicing the invention. Upon reading the following description in light of the accompanying drawings, those skilled in the art will understand the concepts of the invention and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims. 
       FIG. 1  illustrates an exemplary topology of a wireless communication network  10 . In the preferred embodiment, the wireless communication network  10  operates according to the IEEE 802.16j standard or the advanced Long Term Evolution (LTE) standard. However, the embodiments discussed herein may be utilized in any type of wireless communication system and are not limited to the IEEE 802.16j or advanced LTE standard. As illustrated, the wireless communication network  10  includes a base station ( 138 )  12 , a number of relay stations (RSs)  14 - 1  and  14 - 2 , and a number of mobile stations (MSs)  16 - 1  through  16 - 5 . The base station  12  is generally implemented at a fixed location. The base station  12  operates as a wireless access point for mobile stations, such as the mobile station  16 - 1 , located within a wireless coverage area  18  of the base station  12  as well as for mobile stations, such as the mobile stations  16 - 2  through  16 - 5  located within wireless coverage areas  20  and  22  of the relay stations  14 - 1  and  14 - 2 . 
     The relay stations  14 - 1  and  14 - 2  may each be either a fixed relay station (i.e., a relay station having a fixed location) or a mobile relay station (i.e., a relay station having a changing location). For instance, the relay station  14 - 1  may be a fixed relay station implemented at a shopping center in order to provide wireless access to mobile stations, such as the mobile stations  16 - 2  and  16 - 3 , located within the shopping center, and the relay station  14 - 2  may be a mobile relay station implemented on a bus in order to provide wireless access to mobile stations, such as the mobile stations  16 - 4  and  16 - 5 , located within the bus. In the preferred embodiment, each of the relay stations  14 - 1  and  14 - 2  may operate in either an end-to-end mode, which may also be referred to herein as a relay station mode, or a distributed mode, which may also be referred to herein as a base station mode. The operation modes of the relay stations  14 - 1  and  14 - 2  may be configured during a network entry. In an alternative embodiment, the relay stations  14 - 1  and  14 - 2  may have a single mode of operation, which may be either an end-to-end mode or a distributed mode, where at least one of the relay stations  14 - 1  and  14 - 2  is a distributed mode relay station. Note that the details of the end-to-end and distributed modes are discussed below in detail. 
     The mobile stations  16 - 1  through  16 - 5  may each be a user device having a wireless interface for connecting to the wireless communication network  10 . For example, each of the mobile stations  16 - 1  through  16 - 5  may be a mobile telephone, a mobile smart phone, a wireless access card for a personal computer, or the like. 
       FIG. 2  illustrates the operation of the relay station  14 - 1  when operating in the end-to-end mode according to one embodiment of this disclosure. This discussion is equally applicable to the relay station  14 - 2 . Also, while the discussion of  FIG. 2  focuses on an exemplary embodiment where the wireless communication network  10  is an IEEE 802.16j network, one of ordinary skill in the art will readily appreciate that the relay station  14 - 1  operating in end-to-end mode may be utilized in other types of wireless communication networks upon reading this disclosure. In this embodiment, Internet protocol (IP) flow forwarded by a gateway  24  is received at the base station  12 . The base station  12  maps the IP flow to a MS connection (i.e., a connection to one of the mobile stations  16 - 1  through  16 - 5 ). Using IEEE 802.16j as an example, the base station  12  creates an IEEE 802.16e medium access control (MAC) packet data unit (PDU) and may encrypt the MAC PDU. The base station  12  forwards the IEEE 802.16e MAC PDU as part of a relay MAC (R-MAC) PDU flow directed toward the relay station  14 - 1 . The R-MAC PDU flow may include one or more IEEE 802.16e MAC PDUs. The relay station  14 - 1  receives the R-MAC PDU flow and directs packets destined toward the mobile station  16 - 2  to the mobile station  16 - 2  and directs packets destined toward the mobile station  16 - 3  to the mobile station  16 - 3  as IEEE 802.16e MAC PDU flow. If the MAC PDU flow is encrypted, the mobile stations  16 - 2  and  16 - 3  decrypt the IEEE 802.16e MAC PDU. Accordingly, end-to-end connectivity is maintained between the base station  12  and the mobile stations  16 - 2  and  16 - 3  connected via the relay station  14 - 1 . Additionally, end-to-end security and Automatic Repeat Request (ARQ) are maintained between the base station  12  and the mobile stations  16 - 2  and  16 - 3  connected via the relay station  14 - 1 . 
       FIG. 3  illustrates the operation of the relay station  14 - 1  when operating in the distributed mode according to one embodiment of this disclosure. This discussion is equally applicable to the relay station  14 - 2 . Also, while the discussion of  FIG. 3  focuses on an exemplary embodiment where the wireless communication network  10  is an IEEE 802.16j network, one of ordinary skill in the art will readily appreciate that the relay station  14 - 1  operating in distributed mode may be utilized in other types of wireless communication networks upon reading this disclosure. In this embodiment, a transport connection is established between the base station  12  and the relay station  14 - 1  that is dedicated for relaying mobile station traffic, which is traffic to and/or from the mobile stations  16 - 2  and  16 - 3  served by the relay station  14 - 1 . Connections are also established between the relay station  14 - 1  and the mobile stations  16 - 2  and  16 - 3 . Using a downlink as an example, the base station  12  maps downlink service data flows to the mobile stations  16 - 2  and  16 - 3  served by the relay station  14 - 1  to the transport connection of the relay station  14 - 1 . The relay station  14 - 1  maps the downlink service data flows from the base station  12  to the respective connections of the mobile stations  16 - 2  and  16 - 3 . In a similar manner, uplink service data flows from the mobile stations  16 - 2  and  16 - 3  are provided to the relay station  14 - 1  via the corresponding connections, and the relay station  14 - 1  maps the uplink service data flows from the mobile stations  16 - 2  and  16 - 3  to the transport connection to the base station  12 . As such, security, connectivity, and ARQ may be maintained between the base station  12  and the relay station  14 - 1 , and separately maintained between the relay station  14 - 1  and mobile stations  16 - 2  and  16 - 3 . 
     Specifically, with respect to ARQ, an ARQ process is performed by the base station  12  and the relay station  14 - 1  for the transport connection dedicated for relaying mobile station traffic. In addition, if one or more ARQ enabled connections are made between the relay station  14 - 1  and the mobile station  16 - 2 , a separate ARQ process is performed by the relay station  14 - 1  and the mobile station  16 - 2  for each of the ARQ enabled connections. Likewise, if one or more ARQ enabled connections are made between the relay station  14 - 1  and the mobile station  16 - 3 , a separate ARQ process is performed by the relay station  14 - 1  and the mobile station  16 - 3  for each of the ARQ enabled connections. In this manner, rather than having an end-to-end ARQ process between the base station  12  and each of the mobile stations  16 - 2  and  16 - 3 , ARQ is distributed in that an ARQ process is performed for the transport connection between the base station  12  and the relay station  14 - 1  and separate ARQ processes are performed between the relay station  14 - 1  and the mobile stations  16 - 2  and  16 - 3 . 
     Distributed ARQ is beneficial because it reduces overhead in the wireless communication network  10 . More specifically, ARQ related data flow does not need to be relayed between the base station  12  and the mobile stations  16 - 1  through  16 - 5  for each ARQ enabled connection of the mobile stations  16 - 1  through  16 - 5 . In addition, there is reduced delay for distributed ARQ as compared to end-to-end ARQ. In addition, distributed ARQ is particularly beneficial for mobile relay stations. 
       FIG. 4  graphically illustrates an exemplary protocol stack for the base station  12 , the relay station  14 - 1 , and the mobile station  16 - 2 . In addition,  FIG. 4  illustrates an exemplary protocol stack of a standard relay primarily to be contrasted with the protocol stack of the relay station  14 - 1 . As illustrated in  FIG. 4 , the base station  12  maintains a convergence layer and a MAC layer with the relay station  14 - 1 , while the relay station  14 - 1  maintains a separate convergence layer and a separate MAC layer with the mobile station  16 - 2 . The relay station  14 - 1  also maintains a physical (PHY) layer with the mobile station  16 - 2 . In this example, the base station  12  also maintains a PHY layer and a MAC layer, which for IEEE 802.16 are an R-PHY layer and an R-MAC layer, with the standard relay. The standard relay also maintains a MAC layer and a PHY layer, which for IEEE 802.16 are an R-PHY layer and an R-MAC layer, with the relay station  14 - 1 . Note that, as discussed above and illustrated in  FIG. 4 , the ARQ maintained between the base station  12  and the relay station  14 - 1  is separate from the ARQ maintained between the relay station  14 - 1  and the mobile station  16 - 2 . 
     When operating to provide distributed ARQ, the relay stations  14 - 1  and  14 - 2  store ARQ context information for each of the ARQ enabled connections with the mobile stations  16 - 2  through  16 - 5 . For a particular connection, the ARQ context information for that connection includes information defining the state of the ARQ process. As an example, for IEEE 802.16, the ARQ context information for a particular connection may include ARQ related variables such as ARQ_TX_WINDOW_START, ARQ_RX_HIGHEST_BST, and the like. Note, however, that the ARQ context information may vary depending on the particular implementation. 
     Using the mobile station  16 - 2  as an example, when the mobile station  16 - 2  performs a handover from the relay station  14 - 1  to a target station, the relay station  14 - 1 , which is operating in the distributed ARQ mode, forwards the ARQ context information for each ARQ enabled connection of the mobile station  16 - 2  to the base station  12 . The target station may be the base station  12 , another relay station served by the base station  12  such as the relay station  14 - 2 , another base station, or another relay station of another base station. Based on the forwarded ARQ context information, the target station is enabled to maintain the ARQ process for each of the ARQ enabled connections of the mobile station  16 - 2 . As a result, continuity of the ARQ process for each of the ARQ enabled connections of the mobile station  16 - 2  is maintained through and following handover. 
       FIGS. 5A and 5B  illustrate the forwarding of the ARQ context information for the mobile station  16 - 2  during handover of the mobile station  16 - 2  from the relay station  14 - 1  to the base station  12  according to one embodiment of this disclosure. As illustrated in  FIG. 5A , in this embodiment, the mobile station  16 - 2  moves from the wireless coverage area  20  of the relay station  14 - 1  into the wireless coverage area  18  of the base station  12 . In response, a handover process is performed, as will be appreciated by one of ordinary skill in the art upon reading this disclosure. As illustrated in  FIG. 5B , once the handover process is initiated (step  100 ), the relay station  14 - 1  forwards the ARQ context information for one or more ARQ enabled connections to the mobile station  16 - 2  to the base station  12  (step  102 ). Based on the ARQ context information, the base station  12  is then enabled to continue the ARQ process for each of the ARQ enabled connections to the mobile station  16 - 2  (step  104 ). As a result, continuity for the ARQ process is maintained during and after the handover process. Note that  FIG. 5B  only illustrates the forwarding of the ARQ context information for clarity. However, as will be appreciated by one of ordinary skill in the art upon reading this disclosure, numerous additional steps not illustrated in  FIG. 5B  are typically performed during the handover process. 
       FIGS. 6A through 6C  illustrate the forwarding of the ARQ context information for the mobile station  16 - 2  during handover of the mobile station  16 - 2  from the relay station  14 - 1  to the relay station  14 - 2  of the base station  12  according to one embodiment of this disclosure. As illustrated in  FIG. 6A , in this embodiment, the mobile station  16 - 2  moves from the wireless coverage area  20  of the relay station  14 - 1  into the wireless coverage area  22  of the relay station  14 - 2 . In response, a handover process is performed, as will be appreciated by one of ordinary skill in the art upon reading this disclosure. As illustrated in  FIG. 6B , once the handover process is initiated (step  200 ), the relay station  14 - 1  forwards the ARQ context information for one or more ARQ enabled connections of the mobile station  16 - 2  to the base station  12  (step  202 ). In this embodiment, the relay station  14 - 2  operates in the end-to-end mode. As such, based on the ARQ context information, the base station  12  is then enabled to continue the ARQ process for each of the ARQ enabled connections to the mobile station  16 - 2  via the relay station  14 - 2  in an end-to-end manner (steps  204 A/ 204 B). As a result, continuity for the ARQ process is maintained during and after the handover process. 
       FIG. 6C  illustrates the ARQ forwarding process if the relay station  14 - 2  operates in the distributed mode. As illustrated, once the handover process is initiated (step  300 ), the relay station  14 - 1  forwards the ARQ context information for one or more ARQ enabled connections of the mobile station  16 - 2  to the base station  12  (step  302 ). In this embodiment, the relay station  14 - 2  operates in the distributed mode. As such, the base station  12  forwards the ARQ context information to the relay station  14 - 2  (step  304 ). Then, based on the ARQ context information, the relay station  14 - 2  is then enabled to continue the ARQ process for each of the ARQ enabled connections to the mobile station  16 - 2  (step  306 ). As a result, continuity for the ARQ process is maintained during and after the handover process. Again, note that  FIGS. 6B and 6C  only illustrate the forwarding of the ARQ context information for clarity. However, as will be appreciated by one of ordinary skill in the art upon reading this disclosure, numerous additional steps not illustrated in  FIGS. 6B and 6C  are typically performed during the handover process. 
       FIGS. 7A and 7B  illustrate the forwarding of the ARQ context information for the mobile station  16 - 2  during handover of the mobile station  16 - 2  from the relay station  14 - 1  to a base station  26  other than the base station  12  according to one embodiment of this disclosure. As illustrated in  FIG. 7A , in this embodiment, the mobile station  16 - 2  moves from the wireless coverage area  20  of the relay station  14 - 1  into a wireless coverage area  28  of the base station  26 . In response, a handover process is performed, as will be appreciated by one of ordinary skill in the art upon reading this disclosure. As illustrated in  FIG. 7B , once the handover process is initiated (step  400 ), the relay station  14 - 1  forwards the ARQ context information for one or more ARQ enabled connections of the mobile station  16 - 2  to the base station  12  (step  402 ). The base station  12  then forwards the ARQ context information to the base station  26  preferably via a backhaul network (step  404 ). Based on the ARQ context information, the base station  26  is then enabled to continue the ARQ process for each of the ARQ enabled connections to the mobile station  16 - 2  (step  406 ). As a result, continuity for the ARQ process is maintained during and after the handover process. Note that  FIG. 7B  only illustrates the forwarding of the ARQ context information for clarity. However, as will be appreciated by one of ordinary skill in the art upon reading this disclosure, numerous additional steps not illustrated in  FIG. 7B  are typically performed during the handover process. 
       FIGS. 8A through 8C  illustrate the forwarding of the ARQ context information for the mobile station  16 - 2  during handover of the mobile station  16 - 2  from the relay station  14 - 1  to a relay station  30  of the base station  26  according to one embodiment of this disclosure. As illustrated in  FIG. 8A , in this embodiment, the mobile station  16 - 2  moves from the wireless coverage area  20  of the relay station  14 - 1  into a wireless coverage area  32  of the relay station  30 . In response, a handover process is performed, as will be appreciated by one of ordinary skill in the art upon reading this disclosure. As illustrated in  FIG. 8B , once the handover process is initiated (step  500 ), the relay station  14 - 1  forwards the ARQ context information for one or more ARQ enabled connections of the mobile station  16 - 2  to the base station  12  (step  502 ). The base station  12  then forwards the ARQ context information for the one or more ARQ enabled connections of the mobile station  16 - 2  to the base station  26  preferably via a backhaul network (step  504 ). In this embodiment, the relay station  30  operates in the end-to-end mode. As such, based on the ARQ context information, the base station  12  is then enabled to continue the ARQ process for each of the ARQ enabled connections to the mobile station  16 - 2  via the relay station  30  in an end-to-end manner (steps  506 A/ 506 B). As a result, continuity for the ARQ process is maintained during and after the handover process. 
       FIG. 8C  illustrates the ARQ forwarding process if the relay station  30  operates in the distributed mode. As illustrated, once the handover process is initiated (step  600 ), the relay station  14 - 1  forwards the ARQ context information for one or more ARQ enabled connections of the mobile station  16 - 2  to the base station  12  (step  602 ). The base station  12  then forwards the ARQ context information for the one or more ARQ enabled connections of the mobile station  16 - 2  to the base station  26  preferably via a backhaul network (step  604 ). In this embodiment, the relay station  30  operates in the distributed mode. As such, the base station  12  forwards the ARQ context information to the relay station  30  (step  606 ). Then, based on the ARQ context information, the relay station  30  is enabled to continue the ARQ process for each of the ARQ enabled connections of the mobile station  16 - 2  (step  606 ). As a result, continuity for the ARQ process is maintained during and after the handover process. Again, note that  FIGS. 8B and 8C  only illustrate the forwarding of the ARQ context information for clarity. However, as will be appreciated by one of ordinary skill in the art upon reading this disclosure, numerous additional steps not illustrated in  FIGS. 8B and 8C  are typically performed during the handover process. 
       FIG. 9  is a block diagram of an exemplary embodiment of the base station  12  of  FIG. 1 . As illustrated, the base station  12  includes a control system  34 , which may have associated memory  36 . The control system  34  is implemented in hardware. For instance, the control system  34  may be one or more Central Processing Units (CPUs), one or more Application Specific Integrated Circuits (ASICs), one or more Field Programmable Gate Arrays (FPGAs), or the like. The functionality of the base station  12  discussed herein may be implemented in software executed by the control system  34 , implemented in hardware within the control system  34 , or a combination thereof. The base station  12  also includes one or more wireless network interfaces  38  for communicating with the relay stations  14 - 1  and  14 - 2  ( FIG. 1 ) and mobile stations, such as the mobile station  16 - 1 , located within the wireless coverage area  18  of the base station  12 . Lastly, the base station  12  includes a backhaul network interface  40  for communicating with other base stations via a backhaul network. The backhaul network may be a high speed wired or wireless network. 
       FIG. 10  is a block diagram of an exemplary embodiment of the relay station  14 - 1  of  FIG. 1 . This discussion is equally applicable to the relay station  14 - 2 . As illustrated, the relay station  14 - 1  includes a control system  42 , which may have associated memory  44 . The control system  42  is implemented in hardware. For instance, the control system  42  may be one or more CPUs, one or more ASICs, one or more FPGAs, or the like. The functionality of the relay station  14 - 1  discussed herein may be implemented in software executed by the control system  42 , implemented in hardware within the control system  42 , or a combination thereof. The relay station  14 - 1  also includes one or more wireless network interfaces  46  for communicating with the base station  12  and mobile stations, such as the mobile stations  16 - 2  and  16 - 3 , located within the wireless coverage area  20  of the relay station  14 - 1 . 
       FIG. 11  is a block diagram of an exemplary embodiment of the mobile station  16 - 1 . This discussion is equally applicable to the other mobile stations  16 - 2  through  16 - 5 . As illustrated, the mobile station  16 - 1  includes a control system  48 , which may have associated memory  50 . The control system  48  is implemented in hardware. For instance, the control system  48  may be one or more CPUs, one or more ASICs, one or more FPGAs, or the like. The functionality of the mobile station  16 - 1  discussed herein may be implemented in software executed by the control system  48 , implemented in hardware within the control system  48 , or a combination thereof. The mobile station  16 - 1  also includes a wireless network interface  52  for communicating with the base station  12 . Note that if the mobile station  16 - 1  were to move to the wireless coverage area  20  of the relay station  14 - 1 , then the wireless network interface  52  would then enable the mobile station  16 - 1  to communicate with the relay station  14 - 1 . The mobile station  16 - 1  also includes a user interface  54 , which may include components such as a speaker, a microphone, a display, a keypad, or the like. 
     Those skilled in the art will recognize improvements and modifications to the embodiments of the present invention. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.

Metadata:
Filing Date: 20140217
Publication Date: 20160517
Grant Date: 20160517
Priority Date: 20080314
Inventors: ZHANG HANG
ZHU PEIYING
TONG WEN
Assignee: APPLE INC
CPC Classifications: [{"code": "H04B7/15", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L1/18", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W40/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W8/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W40/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W40/22", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04B7/15", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L1/18", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W8/30", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04L1/16", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04B7/15", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04W8/30", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04L1/18", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04W8/30", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 41065605