CLIAMS:1. A wireless relay station, comprising:
at least one mobile station module configured to perform a downlink function comprising decoding and forwarding a first signal corresponding to a first data frame received from a superordinate node;
a relay layer configured to operate according to one or more standards defined for a desired wireless communications network;
at least one base station module connected back-to-back to the mobile station module via the relay layer and configured to perform an uplink function comprising encoding and forwarding a second signal received from the mobile station module to a subordinate node, wherein the second signal corresponds to a second data frame received before the first data frame; and
wherein the uplink function and the downlink function are performed using complete bandwidth available to an associated central base station that is in communication with the wireless relay station.

2. The wireless relay station of claim 1, wherein the base station module is configured to perform the uplink function for the first signal at a first frequency simultaneously with the downlink function for the second signal being performed by the mobile station module at a second frequency different from the first frequency.

3. The wireless relay station of claim 1, wherein the relay station is a decode-and-forward relay node and is configured to operate according to one or more standards defined in IEEE 802.16e.

4. The wireless relay station of claim 1, wherein the relay station is a decode-and-forward relay node and is configured to operate according to one or more standards defined in release 10 of 3GP standards for LTE implementation.

5. A wireless communications system, comprising:
one or more mobile stations;
at least one base station configured to control wireless communications corresponding to the mobile stations in a wireless communications network;
one or more relay stations communicatively coupled to at least one of the mobile stations and the base station, wherein each of the relay stations comprises:
at least one mobile station module configured to perform a downlink function comprising decoding and forwarding a first signal corresponding to a first data frame received from a superordinate node;
a relay layer configured to operate according to one or more standards defined for a desired wireless network;
at least one base station module connected back-to-back to the mobile station module via the relay layer and configured to perform an uplink function comprising encoding and forwarding a second signal received from the mobile station module to a subordinate node, wherein the second signal corresponds to a second data frame received before the first data frame; and
wherein the uplink function and the downlink function are performed using complete bandwidth available to the base station.

6. The wireless communications system of claim 5, wherein the wireless communications network corresponds to a WiMAX network, an LTE network or a combination thereof.

7. The wireless communications system of claim 5, wherein the super-ordinate node comprises one or more of a relay station and a base station, and wherein the subordinate node comprises one or more of a relay station and a mobile station.

8. The wireless communications system of claim 5, wherein the base station and each of the relay stations is configured to implement a customized communications protocol that establishes localized network operations satisfying one or more constraints defined in one or more standards defined for a desired wireless network in each of the relay stations, and wherein the network operations comprise authentication, disconnection, data reception, data transmission, or combinations thereof.

9. A method for enhanced wireless communications, comprising:
providing one or more relay stations comprising a mobile station module connected back-to-back with a base station module in a wireless communications network, wherein each of the relay stations is communicatively coupled to at least a base station, a mobile station, another relay station from the one or more relay stations, or combinations thereof;
providing a customized communications protocol for the base station and the relay stations to establish localized network operations that satisfy corresponding constraints defined in standards corresponding to a desired wireless network in each of the relay stations;
performing an uplink function for a first signal at the base station module in the relay stations simultaneously with a downlink function for a second signal at the mobile station module in the relay stations such that the uplink function and the downlink function are performed at different frequencies using complete bandwidth available to the base station, wherein the second signal is received prior to the first signal.

10. The method of claim 8, wherein the network operations comprise authentication, disconnection, data reception, data transmission, or combinations thereof.
,TagSPECI:BACKGROUND
[0001] Embodiments of the present specification relate generally to wireless networks, and more particularly to a system and method for enhanced multi-relay wireless communications using an efficient wireless relay configuration.
[0002] Wireless communications networks are widely deployed to provide seamless access to information over large geographical regions. Present-day WiMAX (Worldwide Interoperability for Microwave Access) networks, for example, may be used to provide wireless connectivity for communicating information for use in a wide variety of applications such as telecom, defense, and/or telemedicine in real-time. Generally, the WiMAX networks operate using interoperable implementations of the 802.16 family of wireless networks standards defined by the Institute of Electrical and Electronics Engineers (IEEE). The IEEE 802.16 WiMAX standards aid in efficient deployment of voice, video, and data communication services between base stations and corresponding mobile stations. Additionally, use of the IEEE 802.16 WiMAX standards may also support convergence of wireless multimedia services, context awareness, fixed-mobile convergence, quality of service (QoS), and other WiMAX-based services over enhanced wireless communication pathways.
[0003] Availability of seamless WiMAX-based services, however, relies on availability of a robust and extensible backhaul network across large geographical regions. Conventional WiMAX networks often suffer performance degradation at edges of the network due to low signal-to-noise ratio (SNR), shadowing, and/or non-uniform distribution of traffic, thus resulting in a large number of coverage holes. Specifically, such coverage holes may occur in sparsely populated regions, rural areas, non-line of sight regions in urban environments, and/or in-building spaces having limited or no backhaul connectivity. Widespread deployment and maintenance of new WiMAX backhaul networks for servicing these coverage holes across all geographical areas is not only complex but would involve exorbitant costs.
[0004] Accordingly, certain present-day communications networks employ WiMAX enabled multi-hop relays to expand and/or strengthen network coverage and bandwidth over a larger geographical area. Particularly, certain networks employ the multi-hop wireless relay standard defined in IEEE 802.16j that allows use of an intervening relay station between a base station and a subscriber or mobile station. Use of intervening relay stations extends coverage of the communications networks to rural areas and/or improves penetration of WiMAX signals into indoor environments.
[0005] Generally, these relay stations are relatively low-cost and powered network elements configured to decode, store, encode, and wirelessly communicate data received from a base station to a mobile station, and vice versa. Accordingly, distributed placement of the relay stations across network cells reduces propagation losses between the relay stations and the mobile stations, which result in larger link data rates, thereby obviating a need for an expensive wired backhaul connection.
[0006] However, the IEE802.16j frame structure is defined to accommodate each successive relay station such that available uplink (UL) and downlink (DL) bandwidth is equally distributed among successive relay stations. Particularly, the bandwidth is distributed amongst successive relay stations in conventional WiMAX networks to avoid interference between transmission and reception of information at the base stations, the relay stations, and/or the mobile stations. Accordingly, as the number of intervening relay stations increases, the available throughput at a leaf node in a conventional WiMAX network is progressively reduced. Thus, use of the IEE802.16j defined frame structure for WiMAX relay stations significantly limits scalability and/or other performance parameters such as SNR and/or throughput in conventional WiMAX networks.

BRIEF DESCRIPTION
[0007] According to an exemplary aspect of the present specification, a wireless relay station (RS) is presented. The RS includes at least one mobile station (MS) module configured to perform a downlink function comprising decoding and forwarding a first signal corresponding to a first data frame received from a superordinate node. The RS also include a relay layer configured to operate according to one or more standards defined for a desired wireless communications network. The RS further includes at least one base station (BS) module connected back-to-back to the MS module via the relay layer and configured to perform an uplink function comprising encoding and forwarding a second signal received from the MS module to a subordinate node, where the second signal corresponds to a second data frame received before the first data frame, and where the uplink function and the downlink function are performed using complete bandwidth available to an associated central BS in communication with the RS.
[0008] According to another aspect of the present specification, a wireless communications system is disclosed. The system includes one or more MS, at least one BS configured to control wireless communications corresponding to the MS in a wireless communications network. Additionally, the system includes one or more relay stations (RSs) communicatively coupled to at least one of the MS and the BS. Each of the RSs includes at least one MS module configured to perform a downlink function comprising decoding and forwarding a first signal corresponding to a first data frame received from a superordinate node. The RSs also include a relay layer configured to operate according to one or more standards defined for a desired wireless communications network. The RS further includes at least one BS module connected back-to-back to the MS module via the relay layer and configured to perform an uplink function comprising encoding and forwarding a second signal received from the MS module to a subordinate node, where the second signal corresponds to a second data frame received before the first data frame, and where the uplink function and the downlink function are performed using complete bandwidth available to the BS.
[0009] Additionally, in accordance with a further aspect of the present specification, a method for enhanced wireless communications is presented. The method includes providing one or more RSs including a MS module connected back-to-back with a BS module in a wireless communications network, where each of the RSs is communicatively coupled to at least a BS, a MS, another RS from the one or more RSs. Additionally, the method includes providing a customized communications protocol for the BS and the RSs to establish localized network operations that satisfy corresponding constraints defined in standards corresponding to a desired wireless network in each of the RSs. Further, the method includes performing an uplink function for a first signal at the BS module in the RSs simultaneously with a downlink function for a second signal at the MS module in the RSs such that the uplink function and the downlink function are performed at different frequencies using complete bandwidth available to the BS, where the second signal is received prior to the first signal.

DRAWINGS
[0010] These and other features, aspects, and advantages of the claimed subject matter will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
[0011] FIG. 1 is a schematic representation of an exemplary wireless communication system having an efficient wireless relay configuration;
[0012] FIG. 2 is an example of a conventional frame structure defined in IEEE 802.16j for a wireless relay station used in a conventional wireless communication system;
[0013] FIG. 3 is an example of an exemplary frame structure defined according to aspects of the present specification for use by a wireless relay station used in the system described in FIG. 1;
[0014] FIG. 4 is a block schematic representation of certain exemplary components of a relay station used in the wireless communication system of FIG. 1;
[0015] FIG. 5 is a sequence diagram depicting exemplary communications between a base station and a relay station using an example of a customized communications protocol;
[0016] FIG. 6 is a sequence diagram depicting exemplary communications between a relay station and a mobile station using an example of a customized communications protocol;
[0017] FIG. 7 is flow chart depicting an exemplary method for enhanced multi-relay wireless communications using the system and corresponding components described with reference to FIGs. 1-2; and
[0018] FIG. 8 is a block schematic diagram depicting an exemplary configuration of the wireless communication system of FIG. 1 for assessing performance of the present system and method described with reference to FIGs 1, 3, and 4, as compared to performance of a conventional wireless network.

DETAILED DESCRIPTION
[0019] The following description presents exemplary systems and methods for enhanced multi-relay (MR) wireless communications. Particularly, embodiments described herein disclose a technology agnostic wireless relay configuration that may be implemented in different wireless communications networks, such as WiMAX and LTE (Long-Term Evolution) networks, to provide enhanced throughput at corresponding leaf nodes.
[0020] To that end, the present systems and methods include a relay station (RS) having collocated base station (BS) and mobile station (MS) modules that allow for distributed communications between a BS and a RS. Additionally, the BS is also modified via a customized communications protocol to incorporate communication between the BS and RS, thereby mitigating latency issues. Moreover, the present wireless relay configuration eliminates a need for dedicated bandwidth allocation for communications between the RS and the BS, while making the complete bandwidth available for communications between MS and BS. Particularly, the present wireless relay configuration makes the complete bandwidth available for communications between MS and BS by configuring the BS and the RS to employ different frequencies for UL and DL, irrespective of a duplexing technique being used. Availability of the complete bandwidth for the MS-BS communications ensures that, irrespective of a number of intervening relay stations, an effective throughput available at a leaf node is substantially equal to the throughput available between a central BS and an adjacent RS or MS.
[0021] Although exemplary embodiments of the present systems and methods are described with reference to a WiMAX network, it may be appreciated that use of embodiments of the present systems and methods in various other communication networks such as LTE networks is also contemplated. Furthermore, as previously noted, embodiments of the present systems and methods may be implemented irrespective of a duplexing technique for extending coverage of a communications network, while still maintaining network performance at network edges or leaf nodes. An exemplary environment that is suitable for practicing various implementations of the present system is discussed in the following sections with reference to FIG. 1.
[0022] FIG. 1 illustrates an exemplary wireless communication system 100 including an efficient relay configuration for enhanced MR wireless communications. In one embodiment, the system 100 includes at least one BS 102, one or more RS 104, and one or more subscriber stations (SS) or MS 106 in operative association with each other. It may be noted that although FIG. 1 depicts only one BS102, two MS 106, and three RS 104, in certain other embodiments, the system 100 may include any number of base stations, relay stations, and mobile stations. Additionally, even though FIG. 1 depicts two-hop and three-hop communications between the BS 102 and each of the MS 106, the system 100 may allow a greater or fewer number of hops for facilitating communications between the BS 102 and the MS 106. Moreover, the BS 102, the RS 104, and/or the MS 106 may employ any desired duplexing technique such as time division duplexing (TDD) or frequency division duplexing (FDD).
[0023] In accordance with aspects of the present specification, the BS 102 provides connectivity management and control of the MS 106 and the RS 104 for enabling communications between the BS 102, RS 104, and/or MS 106 within a specific network region. In one embodiment, the BS 102 is communicatively coupled to a core wireless communications network 108 such as a WiMAX and/or an LTE network via a backhaul (not shown in FIG. 1) to support the connectivity management and control functions corresponding to the RS 104 and/or the MS 106.
[0024] In certain embodiments, the MS 106 may correspond to a stationary or a mobile device that operates under control of the BS 102 and/or the RS 104. Particularly, the MS 106 may include devices such as a cellular phone, a personal digital assistant (PDA), a wireless modem, a handheld device, a laptop computer, and/or a cordless phone. In one embodiment, the MS 106 may be configured to receive communication from the BS 102 and/or the RS 104 via DL, and communicate information to the RS 104 and/or the BS 102 via UL.
[0025] Further, according to certain aspects of the present specification, the RS 104 may be configured to provide management and control of subordinate relay stations and/or mobile stations. To that end, in one embodiment, the RS 104 may correspond to a powered device that may be communicatively coupled to the BS 102 to support multi-hop communication in the wireless network 108. Additionally, the RS 104 may correspond to a fixed, nomadic, and/or mobile relay stations that may be selectively configured to aid in providing desired connectivity even at the leaf nodes of the wireless network 108.
[0026] Generally, relay stations correspond to amplify-and-forward or decode-and-forward relay nodes. The amplify-and-forward relays may be transparent to both base stations and mobile stations and may be configured to simply amplify and forward received analog signals including noise and interference. Accordingly, the amplify-and-forward relays are typically used in high signal-to-noise ratio (SNR) environments. In contrast, decode-and-forward relays decode and re-encode the received signals prior to forwarding it to an associated relay transmitter. The decode-and-forward relays do not amplify noise and interference, and thus, are also useful in low-SNR environments.
[0027] Conventionally, the decode-and-forward relays may be configured to decode a signal received from a base station, thereby providing DL functionality similar to that of a MS. Additionally, the decode-and-forward relays may also be configured to encode and transmit the signal to one or more subordinate relay stations or mobile stations, thus providing DL functionality corresponding to a BS. An efficient network transmission entails simultaneous UL and DL operations. Accordingly, sufficient separation in time and/or in spectral space is employed for UL and DL signal in conventional wireless communications networks to prevent interference between the UL and DL operations.
[0028] Accordingly, conventional relay stations employ a frame structure defined in the IEE802.16j standard that distributes available UL and DL bandwidth among successive relay stations to provide the necessary time and/or spectral separation. However, as previously noted, the distribution of bandwidth amongst successive network nodes degrades network performance, especially at the leaf nodes in the network. Use of the IEE802.16j frame structure, thus, will result in undesirable performance degradation at the edges of the wireless network 108. The IEE802.16j frame structure used by conventional relay stations and corresponding shortcomings will be described in greater detail with reference to FIG. 2.
[0029] Particularly, FIG. 2 illustrates an exemplary representation 200 of a timing diagram corresponding to a data frame 202 defined using the IEE802.16j standard. The frame 202, for example, may be an FDD or a TDD frame. In the example depicted in FIG, 2, the DL frame duration for the FDD frame 202 is 5 milliseconds (ms). During conventional IEE802.16j communications, the DL frame duration of 5 ms may be further divided, for example, into P1 and P2 durations such that a sum of P1 and P2 equals 5 ms. Generally, a conventional BS may be configured to transmit data addressed to an intervening RS and corresponding child nodes during P1, while P2 remains silent and unused during the BS-RS transmission. The transmitted data may be stored in the RS, which in turn, may retransmit the data addressed to the child nodes during P2. Thus, an effective bandwidth available at the child nodes is reduced because the duration of transmission is limited to P2 instead of the entire 5 ms available to the FDD frame 202.
[0030] Consequently, if additional RS are present in a network path between the BS and the MS, an effective DL bandwidth will progressively reduce, for example, by half of the bandwidth that is available at a preceding RS. Conversely, it may be stated that the DL bandwidth available at a leaf node in a wireless communications network is inversely proportional to a number of conventional relay stations present in between the BS and the MS. Similarly, an effective UL bandwidth available at a leaf node in a wireless communications network will also be inversely proportional to the number of conventional relay stations present in between the BS and the MS, thereby impeding QoS and/or scalability of the wireless communications network.
[0031] With returning reference to FIG. 1, unlike such conventional relay stations, the RS 104 of FIG. 1 includes custom architecture that eliminates a need for dedicated bandwidth allocation for communications between the RS 104 and the BS 102. Instead, the custom architecture of the RS 104 allows the entire available bandwidth to be used for communications between MS 106 and the BS 102.
[0032] FIG. 3 illustrates an exemplary representation 300 of a timing diagram corresponding to data frame 302 used by the RS 104 of FIG. 1 in accordance with aspects of the present specification. Particularly, the timing diagram shows that an entire frame duration of 5 ms is available for data transmission from the BS 102 (see FIG. 1) to the RS 104, and in turn, from the RS 104 to subsequent child nodes such as the MS 106 (see FIG. 1). Particularly, the RS 104 employs a custom architecture that allows for simultaneous UL and DL of different data frames at different frequencies, thereby allowing use of the entire 5 ms for communications between the BS 102 and the MS 106. Accordingly, even as a number of RS 104 increases in a network path, the bandwidth available at the MS 106 located at the leaf node remains substantially the same as the bandwidth available at a node that is directly connected to the BS 102.
[0033] According to certain aspects of the present specification, the RS 104 allows for the allocation of the entire bandwidth by employing the custom architecture and customized communications protocol that delays data transmission by a determined number of frames. The custom architecture and the customized communications protocols used for facilitating robust data transmission between the BS 102, the RS 104, and the MS 106 will be described in greater detail with reference to FIGs. 4-7.
[0034] FIG. 4 illustrates a block schematic diagram 400 of an exemplary architecture of a RS such as the RS 104 of FIG. 1 to allow for enhanced multi-hop or MR wireless communications. To that end, the RS 104 includes at least one MS module 402 co-located with at least one BS module 404 and a relay layer 406. The MS module 402, in turn, may include a MS media access (MAC) layer 408, a MS physical layer 410, and a MS radio unit 412 configured to receive and/or retransmit signals. Similarly, the BS module 404 may include a BS MAC layer 414, a BS physical layer 416, and a BS radio unit 418 configured to receive and/or transmit signals. In certain embodiments, both the MS and BS physical layers 410 and 416 are designed and/or configured to adhere to the IEEE802.16e defined standards, thus ensuring backward compatibility of the RS 104 and the system 100 of FIG. 1, while still providing enhanced throughput across the wireless network 108 irrespective of a number of intervening RS.
[0035] To that end, in one embodiment, the MS module 402 includes WiMAX 16e Mobile Station software that is connected back-to-back to WiMAX 16e Base Station software in the BS module 404 to provide decode-and-forward functionality. Accordingly, signals transmitted by the central BS 102 (see FIG. 1) are received at the MS radio unit 412 for decoding and/or storage via use of the WiMAX 16e Mobile Station software. Subsequently, the decoded signal is transmitted to the BS module 404 for encoding and transmission to a desired subordinate node such as a subsequent RS or a MS in the wireless network 108.
[0036] Addition of co-located MS and BS modules 402 and 404 allows the RS 104 to provide simultaneous DL and UL operations at different frequencies. As used herein, the term “simultaneous” and variations thereof are used to refer to a specified frame duration, for example, of about 5 milliseconds (ms) for WiMAX-based implementations and about 1 ms for LTE-based implementations. Specifically, in one embodiment, the custom architecture of the RS 104 allows the MS module 402 to DL a data frame “N” received from a super-ordinate BS such as the BS 102 of FIG. 1 or another RS at a first frequency, while the BS module 404 simultaneously downlinks the re-encoded data frame “N-1” to a subordinate RS or MS 106 at a second frequency.
[0037] Thus, the co-located MS-BS architecture allows use of the entire bandwidth and/or the entire frame duration for communication between the BS 102 and the MS 106 by delaying transmission of one or more previously received data frames to subordinate nodes and use of different UL and DL frequencies. Such simultaneous and/or distributed processing of the DL and UL data frames enabled by the custom RS architecture aids in increasing an overall throughput of the wireless network 108. Furthermore, in certain embodiments, the UL and DL of the data frames performed using different carrier frequencies in the RS 104 avoids interference, thus providing MR wireless communications having desired QoS irrespective of a duplexing technique being used in the wireless network 108.
[0038] It may be noted that although the RS 104 is described with reference to a WiMAX network, embodiments of the present architecture of the RS 104 may similarly be used in LTE networks, where the MS 106 and BS 102 may be substituted with user equipment (UE) and evolved Node B (eNodeB), respectively. Additionally, in certain embodiments, both the MS and BS physical layers 410 and 416 may be designed and/or configured to adhere to the Release 10 of 3GP standards defined for LTE-based implementations, thus ensuring backward compatibility of the RS 104. The custom architecture, thus, may be advantageously implemented in wireless networks irrespective of the underlying technology being used.
[0039] With returning reference to FIG. 1, the custom architecture is supported by customized communication protocols between the RS 104, the BS 102, and the MS 106 to allow for desired functionality of the BS 102, the RS 104, and the MS 106. In one embodiment, each RS handles the requests from sub-ordinate RS/MS and then informs its super-ordinate RS or MR-BS such that all requests from leaf MS travel up to the MR-BS, and only then does the MS receive a response. Thus, the customized protocol may configure the RS 104 to operate in a decentralized relay mode, where the RS 104 appears as a MS for the BS 102, but as a BS for the MS 106. Particularly, the customized protocol may configure the RS 104 to build its own media access layer (MAC) frame conforming to requirements of the IEEE 802.16 MAC frame.
[0040] Additionally, in one embodiment, the communications protocols may be customized to establish localized connection admission in each RS 104 to satisfy constraints of admission defined by the underlying technology standards. For example, the communications protocols may be customized to establish localized connection admission in each RS 104 to satisfy IEEE 802.16e for WiMAX and/or Release 10 (3GPP TS 36.216 V10.0.0 (2010-09)) for LTE-based implementations. Similarly, the communications protocols may be customized to establish localized authentication, disconnection, data reception, data transmission, and/or other network functions in each RS 104 that continue to satisfy corresponding constraints defined by the underlying networking standards.
[0041] In one embodiment, for example, the RS 104 may take over user-equipment registration functions that are typically performed by a central or multi-relay BS. Accordingly, the RS 104 may be configured to generate an ADD-ENTITY message within a desired time period when the MS 106 enters the wireless network 108. Subsequently, the RS 104 communicates a proprietary user registration message to a super-ordinate RS or the BS 102 for registering the MS 106 with the BS 102. Subsequent RS 104 along a network path may be configured to forward the proprietary user registration message within a given time frame until the message is received at the BS 102. In one exemplary implementation, the customized communications protocol may also define a protocol for the BS 102 that allows registration of the MS 106 despite delay in receipt of the proprietary user registration message at the BS 102.
[0042] Further, in certain embodiments, the RS 104 may be configured to receive an ADD-CONNECTION message from a super-ordinate RS or the BS 102. Upon receiving the ADD-CONNECTION message, in one embodiment, the RS 104 is configured to initiate service flow creation procedures such as initiating Digital Signature Algorithm-Request/Response/Acknowledgment (DSA-REQ/RSP/ACK) with the registered MS 106 or to alternatively forward the ADD-CONNECTION message to the subordinate RS 104. Similarly, for de-registering a network device, the RS 104 may be configured to receive a REMOVE-ENTITY message from super-ordinate RS 104 or the BS 102. Upon receiving the REMOVE-ENTITY message, the RS 104 may be configured to initiate network exit procedure with the MS 106 or process and forward the REMOVE-ENTITY message to the subordinate RS 104. Alternatively, the RS 104 may be configured to receive the REMOVE-ENTITY message from a subordinate RS 104, process, and forward the message to a super-ordinate RS 104 or to the BS 102. Additionally, in certain embodiments, the RS 104 may be configured to receive DL data, identify transport connection identifier (CID) associated with the data, and forward the data to a subordinate RS 104 or a desired MS 106.
[0043] In certain embodiments, the communications protocols employed by the BS 102 may be customized to incorporate communication between the BS 102, the RS 104, and/or the MS 106. Certain exemplary customizations of the customized communications protocols will be described in greater detail with reference to FIGs. 5-6.
[0044] Particularly, FIG. 5 illustrates an exemplary sequence diagram 500 depicting examples of customized messaging between an MR-BS such as the BS 102 of FIG. 1 and an embodiment of the RS 104 described with reference to FIGs.1 and 4. In one embodiment, the customized messaging entails transmission of RS Indication Type/Length/Value (TLV) and a Relay Station Identifier (RS1 ID) to the MR-BS as part of a Ranging request (RNG-REQ). Upon receiving the RNG-REQ, the MR-BS updates one or more parameters such as MS identifier (MSID) and entity type in its network topology table. The network topology table records the details of RSs and MSs connected in the MR-BS and details of intermediate nodes in a path from MR-BS to the last MS. In the embodiment depicted in FIG. 5, the MSID corresponds to RS1 and the entity type corresponds to RS.
[0045] Additionally, in certain embodiments, the MR-BS is configured to receive Path_Reg_Req from ASN. Upon receiving Path_Reg_Reg, MR_BS creates a transport connection for RS1 in UL direction (TRS1U) and a transport connection for RS1 in DL direction (TRS1D) with appropriate QoS and CS Parameters received from ASN in Path_Reg_Req. To that end, in one embodiment, the MR-BS maintains one or more data routing and forwarding tables for DL connections and data forwarding table for UL connections. For example, upon receiving the Path_Reg_Req from ASN, MR-BS updates DL CID, Direct (Y)/Indirect (N) connection, and Forward (FWD) CID fields in an associated MR-BS DL FWD CID table. . Additionally, the MR-BS may also update UL CID field in an associated MR-BS UL CID table. In the embodiment depicted in FIG. 5, DL CID corresponds to TRS1D. Moreover, as there is no relay station between RS1 and MR-BS since the RS1 is connected directly to the MR-BS, there is no Forward CID.
[0046] Furthermore, in one embodiment, whenever MR-BS receives any data from ASN, the MR-BS identifies the intended recipient as an intermediate RS or a directly connected (RS/MS) by using the DL FWD CID Table. If the payload needs to be forwarded to an intermediate RS, then a corresponding CID belonging to RS is appended (pre-pended) to the payload and sent to RS. However, if the payload needs to be forwarded to a directly connected level RS/MS, then the payload is forwarded as is. Moreover, in the embodiment depicted in FIG. 5, the TRS1U corresponds to UL CID, which is updated in the MR-BS UL CID table. Additionally, when the MR-BS receives any data from subordinate nodes (RS/MS), the MR-BS checks the received CID in the MR-BS UL CID table and then forwards the received data to ASN based on a protocol corresponding to the identified subordinate node.
[0047] Further, upon receiving Path-Reg-Req from ASN, MR-BS communicates a DSA-Req to RS1. In one embodiment, the MR-BS transmits TRS1U, TRS1D, QoS, and CS Parameters to the RS 1 as part of the DSA-Req. In certain embodiments, the MR-BS may be configured to transmit TRS1U as UL CID as part of a UL data packet. Moreover, the RS1 may be configured to transmit a Dynamic Host Configuration Protocol (DHCP) Discover message on TRS1U ID. In one embodiment, the MR-BS retrieves the RSID (RS1) based on the UL CID (TRS1U) and forwards the DHCP Discover message to ASN. The ASN, in response, transmits a payload containing DHCP Offer message to the MR-BS. Upon receiving the payload containing DHCP offer, the MR-BS identifies that the message is intended for RS1, which is directly connected to MR-BS. Accordingly, the MR-BS forwards the payload, as is, to the RS1. Upon receiving the payload including the DHCP Offer, the RS evaluates the DHCP offer to determine if the payload is intended for the RS. If the payload is intended for the RS, the RS receives and processes the payload based on a specified protocol.
[0048] Furthermore, FIG. 6 illustrates an exemplary sequence diagram 600 depicting examples of customized messaging between the RS 104 and a BS such as the MS 102 of FIG. 1. In one embodiment, once the MS1 registers with RS1 (BS/MS), the RS1 transmits an ADD_Entity message to the MR-BS. The ADD_Entity message, for example, includes MS parameters such as MS Registration (REG) Context, MS1ID, Entity Type, and the list of RSs between MS1 and the current RS, that is, RS1. Upon receiving the ADD_Entity message, MR-BS updates its network topology table with MSID, Entity Type, and the list of RSs between MS1 and MR-BS. Subsequently, the MR-BS transmits an ADD_Entity_Success response to RS1.
[0049] Further, upon receiving Path_Reg_Req from the ASN, the MR-BS updates its MR-BS DL FWD CID Table and MR-BS UL CID Table. Accordingly, as per the sequence depicted in FIG. 5, MR-BS updates an entry for TMS1D in its MR-BS DL FWD CID table, where the entry includes forward CID as TRS1D as the MS is connected through RS1. Similarly, the MR-BS UL CID Table includes TRS1U and TMS1U. Once, both the MR-BS DL FWD CID and MR-BS UL CID Tables are updated, the MR-BS transmits an ADD_Connection message to RS1. Then, RS1 transmits a DSA-Req message to MS1 and upon receiving corresponding DSA RSP/ACK messages, the RS1 further transmits an ADD_Connection_Success message to the MR-BS.
[0050] Further, in one embodiment, the RS1 receives the DHCP Discover message as payload from MS1 on a Transport Connection for MS1 in Uplink direction (TMS1U). RS1 forwards the payload to a super-ordinate RS or MR-BS. The MR-BS, in turn, forwards it to the ASN. Specifically, the MR-BS, on reception of a DHCP offer, maps the received payload to a corresponding MS and/or intermediate RS(s). In one embodiment, the DHCP ACK is intended for MS1, which is connected through RS1. Accordingly, the MR-BS pre-pends TRS1D in the payload and communicates it to RS1. In certain embodiments, upon receiving the data message from the MR-BS, the RS1 maps the message as data intended for MS1 and accordingly forwards the originally received data to MS1.
[0051] Customization of the BS-RS and RS-MS communications protocols mitigates delayed transmission and/or reception of data frames, thus allowing for faster network registration and allocation of the complete bandwidth for BS-MS communications without impeding requisite network operations. An exemplary method for enhanced multi-relay wireless communications using the custom RS architecture and customized BS and RS communications protocols will be described in greater detail with reference to FIG. 7.
[0052] FIG. 7 illustrates a flow chart 700 depicting an exemplary method for enhanced multi-relay wireless communications. Embodiments of the exemplary method may be described in a general context of computer executable instructions on a computing system or a processor. Generally, computer executable instructions may include routines, programs, objects, components, data structures, procedures, modules, functions, and the like that perform particular functions or implement particular abstract data types.
[0053] Embodiments of the exemplary method may also be practiced in a distributed computing environment where optimization functions are performed by remote processing devices that are linked through a wired and/or wireless communication network. In the distributed computing environment, the computer executable instructions may be located in both local and remote computer storage media, including memory storage devices.
[0054] Further, in FIG. 7, the exemplary method is illustrated as a collection of blocks in a logical flow chart, which represents operations that may be implemented in hardware, software, or combinations thereof. The various operations are depicted in the blocks to illustrate the functions that are performed, for example, simultaneous UL and DL phase in the exemplary method. In the context of software, the blocks represent computer instructions that, when executed by one or more processing subsystems, perform the recited operations.
[0055] The order in which the exemplary method is described is not intended to be construed as a limitation, and any number of the described blocks may be combined in any order to implement the exemplary method disclosed herein, or an equivalent alternative method. Additionally, certain blocks may be deleted from the exemplary method or augmented by additional blocks with added functionality without departing from the spirit and scope of the subject matter described herein. For discussion purposes, the exemplary method will be described with reference to the elements of FIGs. 1-4.
[0056] As previously noted, conventional wireless communications systems employ data frame structures defined in IEEE 802.16j standards for multi-relay communications. Particularly, the IEEE 802.16j data frames accommodate each successive relay station such that available UL and DL bandwidth is equally distributed among successive RS to avoid interference between transmission and reception of information at the BS, the RS, and/or the MS. Accordingly, as the number of RS increases, the available throughput at a leaf node is progressively reduced. Thus, use of the IEE802.16j defined frame structure for WiMAX RS significantly limits scalability and/or other performance parameters of conventional WiMAX networks
[0057] Embodiments of the present method alleviate these shortcomings of the IEE802.16j-based multi-relay networks by use of a custom RS architecture and customized communications protocols. Specifically, in one embodiment, the method begins at step 702, where one or more RS 104 (see FIG. 1 and 4) including an MS module 402 (see FIG. 4) connected back-to-back with a BS module 404 (see FIG. 4) is provided in a wireless communications network 108 (see FIG. 1). An exemplary architecture of such an RS is described in detail with reference to FIG. 4.
[0058] Additionally, at step 704, a customized communications protocol may be provided for the BS 102 and the RS 104 to establish localized network operations that satisfy corresponding constraints defined by underlying networking standards in each of the RS 104. For example, when implementing the present method in a WiMAX network, the communications protocol for the BS 102 and the RS 104 may be customized to establish localized network operations that satisfy corresponding constraints defined by IEEE 802.16e standards. However, when implementing the present method in an LTE network, the communications protocol for the eNodeB and the RS 104 may be customized to establish localized network operations that satisfy corresponding constraints defined by Release 10 of the 3GPP standards for LTE implementations.
[0059] Further, at step 706, a UL function for a first signal is performed at the BS module in the RS symmetrically and/or simultaneously with a DL function for a second signal at the MS module in the RS. Particularly, the UL and DL are performed simultaneously at different frequencies using the complete bandwidth, where the second signal corresponds to a second data frame that is received before a first data frame corresponding to the first signal. Specifically, in an exemplary implementation, the custom architecture of the RS 104 allows the MS module 402 to DL a data frame “N” received from the super-ordinate BS 102 or another RS, while the BS module 404 simultaneously downlinks the re-encoded data frame “N-1” to a subordinate RS 104 or MS 106. Thus, the co-located MS-BS architecture allows use of the entire bandwidth and/or the entire frame duration for communication between the BS 102 and the MS 106 by delaying transmission of one or more previously received data frames to subordinate nodes and using different UL and DL frequencies.
[0060] As previously noted, simultaneous and/or distributed processing of the DL and UL data frames enabled by the custom RS architecture aids in increasing an overall throughput of the wireless network 108. Additionally, in certain embodiments, using different carrier frequencies for simultaneous UL and DL provides enhanced throughput and avoids interference, thus providing wireless communications having desired quality of service (QoS) even at the leaf nodes in the wireless network. An exemplary network performance derived by implementing an embodiment of the present method in a WiMAX network is discussed in greater detail with reference to FIG. 8.
[0061] Particularly, FIG. 8 depicts a block schematic diagram 800 of an exemplary network configuration that allows for direct communications between a BS and leaf nodes directly, and via a two-hop relay configuration. In one embodiment, the BS corresponds to a MR-BS or a central access point802 similar to the BS 102 of FIG. 1 and/or the MR-BS of FIGs. 5-6. Further, the leaf nodes correspond to a MS 804 that is in direct communications with the MR-BS 802, and another MS 806 that is communicatively coupled to the MR-BS 802 via RS 808 and RS 810. According to aspects of the present specification, the RS 808 and 810 employ the custom architecture and the customized communications protocols described herein with reference to FIGs. 4, and 5-7, respectively. Thus, the RS 808 and 810 allow for simultaneous UL and DL operations over the complete bandwidth by delaying the data frame transmission by one or more determined frames and using different UL and DL frequencies. Use of the complete bandwidth prevents progressive degradation of network performance as a number of RS between the MS and the MR-BS 802 increases.
[0062] In one exemplary implementation, throughput values were measured at the MS 804 and the MS 806 in the wireless network to assess a corresponding performance. Certain operating parameters of the wireless network used for the exemplary implementation are listed in the following Table 1.
[0063] Table 1 – Operating Parameters

Parameter Value
Frequency 2.3 Gigahertz (GHz) to 2.7 GHz
Bandwidth 5 MHz
Mode of Operation Single Input Single Output (SISO)
Modulation: DL 64 Quadrature Amplitude Modulation (QAM)
Modulation: UL UL: 16 QAM
OFDMA PHY Mode FDD
Encoding type Convolution Code (CC)

[0064] Further, the throughput values measured at MS 804 and MS 806 are listed in Table 2.
[0065] Table 2 – System Performance Parameters

Mode & modulation Throughput-MS 804 Throughput-MS 806
DL 64 QAM 9 Mbps 9 Mbps
16 QAM 7 Mbps 7 Mbps
UL 16 QAM 7 Mbps 7 Mbps

[0066] As evident from the notations in Table 2, use of an embodiment of the present system and/or method results in substantially the same throughput at the leaf node, MS 806, as the throughput measured at MS 804 that is directly connected to the MR-BS 802.
[0067] In contrast, Table 3 lists throughput values measured at MS 804 and MS 806 when the RS 808 and 810 correspond to conventional 802.16j RS and the MR-BS 802 corresponds to a conventional MR-BS.
[0068] Table 3 – Conventional System Performance Parameters

Mode & modulation Throughput-MS 804 Throughput-MS 806
DL 64 QAM 9 Mbps 2.25 Mbps
16 QAM 7 Mbps 1.75 Mbps
UL 16 QAM 7 Mbps 1.75 Mbps

[0069] As evident from the notations in Table 3, use of conventional RS results in progressive degradation of throughput due to an increase in number of intervening RS between the MS 806 and the conventional MR-BS 802 as compared to the performance measured at the MS 804 that is directly connected to the conventional MR-BS 802.
[0070] Thus, unlike conventional wireless networks that suffer from progressive performance degradation with increase in a number of intervening nodes, the present system and method may be used to provide consistent network performance to network nodes irrespective of a number of nodes in between these nodes and the MR-BS.
[0071] Embodiments of the present specification, thus, provide consistent network performance to desired network nodes irrespective of a number of nodes in between the desired nodes and the MR-BS 802. More particularly, use of the custom RS architecture including co-located MS and BS modules aids in simultaneous UL and DL operations over the complete bandwidth using different frequencies, thereby improving network coverage and capacity goals at low cost without the need of a cable or fiber access. Additionally, a duplexing-agnostic and/or networking standard-agnostic configuration of the custom RS architecture and customized protocols allows use of the present system and method to alleviate the shortcomings of different types of conventional multi-relay networks such as WiMAX and LTE networks.
[0072] It may be noted that the foregoing examples, demonstrations, and process steps that may be performed by certain components of the present systems, for example, by the BS 102, the RS 104, the MS 106 (see FIG. 1), the MS module 402, the BS module 404 (see FIG. 4), MR-BS, and RS1, (See FIGs. 5-6) may be implemented by suitable code on a processor-based system, such as a general-purpose or a special-purpose computer. It may also be noted that different implementations of the present specification may perform some or all of the steps described herein in different orders or substantially concurrently.
[0073] Additionally, various functions and/or method steps described in may be implemented in a variety of programming languages, including but not limited to Ruby, Hypertext Pre-processor (PHP), Perl, Delphi, Python, C, C++, or Java. Inventors – Please mention any specific programming languages or software to be noted here. Such code may be stored or adapted for storage on one or more tangible, machine-readable media, such as on data repository chips, local or remote hard disks, optical disks (that is, CDs or DVDs), solid-state drives, or other media, which may be accessed by the processor-based system to execute the stored code.
[0074] Although specific features of various embodiments of the present systems and methods may be shown in and/or described with respect to some drawings and not in others, this is for convenience only. It is to be understood that the described features, structures, and/or characteristics may be combined and/or used interchangeably in any suitable manner in the various embodiments, for example, to construct additional assemblies and techniques for use in wireless communications.
[0075] While only certain features of the present systems and methods have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.