WO2017201027A2 - Enhancements for ieee 802.11ah relays - Google Patents

Abstract

Methods, systems, and apparatuses are disclosed for reachable address updates in wireless systems. A reachable address table may be stored in a forwarding database of a relay. The reachable address table may include routing information for one or more stations (STAs) and one or more relays associated with the relay. A change in association status of a STA may be determined and the reachable address table may be updated to include updated routing information of with the STA. A reachable address update may be sent to an upstream relay. The reachable address update may include the updated routing information for only the changed STA, such that the upstream relay does not overwrite routing information for the one or more STAs and the one or more relays in its own forwarding database.

Description

ENHANCEMENTS FOR IEEE 802.11 AH RELAYS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional

Application No. 62/337, 100 filed on May 16, 2016, the contents of which is hereby incorporated by reference herein.

BACKGROUND

[0002] The IEEE 802.11ah wireless networking protocol uses sub-1 GHz bands to provide extended range wireless networks, compared to wireless networks operating in the 2.4 GHz and 5 GHz bands. These networks may benefit from lower energy consumption, allowing the creation of large groups of stations or sensors that cooperate to share the signal, thus supporting the concept of the Internet of Things (IoT).

SUMMARY

[0003] Methods, systems, and apparatuses are disclosed for performing reachable address updates in wireless systems. A relay may store a reachable address table in a forwarding database. The reachable address table may include routing information for one or more stations (STAs) and one or more relays associated with the relay. The relay may determine a change in association of a STA with the relay. The relay may update the reachable address table to include updated routing information of the STA. The relay may send a reachable address update to an upstream relay comprising the updated routing information for only the STA with the changed association. The upstream relay may not overwrite routing information for the one or more STAs and the one or more relays in its own forwarding database.

[0004] A relay may store a reachable address table in a forwarding database. The reachable address table may include routing information for one or more stations (STAs) and one or more relays associated with the relay. The relay may receive a reachable address update from a downstream relay. The reachable address update may include updated routing information for only a downstream STA with a changed association status. The relay may compare the received updated routing information for the downstream STA in the reachable address update with routing information in the relay's reachable address table. The relay may determine whether to send an upstream reachable address update comprising the updating routing information for only the downstream STA to an upstream relay.

[0005] A relay may receive a message from an upstream relay to initiate a removal of an outdated reachable address in a forwarding database. The message may include an old initiator media access control (MAC) address of a downstream relay and a station (STA) MAC address of a STA that is no longer associated with the downstream relay. The relay may compare the old initiator MAC address and the STA MAC address to routing information for the STA in the forwarding database. The relay may update the forwarding database.

[0006] A relay may receive a reachable address update from a downstream relay. The he reachable address update may include updated routing information for only a downstream station (STA) with a changed association status. The relay may compare an identity of the downstream relay with an identity of a forwarding relay associated with the downstream STA in a forwarding database of the relay. Upon determining that the identity of the downstream relay and the identity of the forwarding relay are different, the relay may update the forwarding database. The relay may send a message to the forwarding relay indicating removal of the STA from the forwarding relay's forwarding database.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings wherein:

[0008] FIG. 1A is a system diagram of an example communications system in which one or more disclosed embodiments may be implemented; [0009] FIG. IB is a system diagram of an example wireless transmit/receive unit (WTRU) that may be used within the communications system illustrated in FIG. 1A;

[0010] FIG. 1C is a system diagram of an example radio access network and an example core network that may be used within the communications system illustrated in FIG. 1A;

[0011] FIG. 2 is a diagram illustrating relay architecture;

[0012] FIG. 3 is. a diagram of a relay element;

[0013] FIG. 4A is a diagram of a reachable address update element;

[0014] FIG. 4B is a diagram of a reachable address field;

[0015] FIG. 5 is a diagram illustrating a first differential reachable address update;

[0016] FIG. 6 is a diagram illustrating a second differential reachable address update;

[0017] FIG. 7 is a diagram illustrating a root AP-initiated removal of an outdated reachable address;

[0018] FIG. 8 is a diagram of a first enhanced relay element; and

[0019] FIG. 9 is a diagram of a second enhanced relay element.

DETAILED DESCRIPTION

[0020] FIG. 1A is a diagram of an example communications system 100 in which one or more disclosed embodiments may be implemented. The communications system 100 may be a multiple access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communications system 100 may enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communications systems 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), and the like.

[0021] As shown in FIG. 1A, the communications system 100 may include wireless transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) 104, a core network 106, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and/or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, consumer electronics, and the like.

[0022] The communications systems 100 may also include a base station

114a and a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the core network 106, the Internet 110, and/or the other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a Home Node B, a Home eNode B, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and/or network elements.

[0023] The base station 114a may be part of the RAN 104, which may also include other base stations and/or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and/or the base station 114b may be configured to transmit and/or receive wireless signals within a particular geographic region, which may be referred to as a cell (not shown). The cell may further be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In another embodiment, the base station 114a may employ multiple -input multiple-output (MIMO) technology and, therefore, may utilize multiple transceivers for each sector of the cell.

[0024] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0025] More specifically, as noted above, the communications system

100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 116 using wideband CDMA (WCDMA). WCDMA may include communication protocols such as High-Speed Packet Access (HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High- Speed Downlink Packet Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

[0026] In another embodiment, the base station 114a and the WTRUs

102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

[0027] In other embodiments, the base station 114a and the WTRUs

102a, 102b, 102c may implement radio technologies such as IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 IX, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the like.

[0028] The base station 114b in FIG. 1A may be a wireless router, Home

Node B, Home eNode B, or access point, for example, and may utilize any suitable RAT for facilitating wireless connectivity in a locahzed area, such as a place of business, a home, a vehicle, a campus, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the core network 106.

[0029] The RAN 104 may be in communication with the core network

106, which may be any type of network configured to provide voice, data, applications, and/or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. For example, the core network 106 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and/or perform high- level security functions, such as user authentication. Although not shown in FIG. 1A, it will be appreciated that the RAN 104 and/or the core network 106 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to the RAN 104, which may be utilizing an E-UTRA radio technology, the core network 106 may also be in communication with another RAN (not shown) employing a GSM radio technology.

[0030] The core network 106 may also serve as a gateway for the

WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and/or other networks 112. The PSTN 108 may include circuit-switched telephone networks that provide plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the transmission control protocol (TCP), user datagram protocol (UDP) and the internet protocol (IP) in the TCP/IP internet protocol suite. The networks 112 may include wired or wireless communications networks owned and/or operated by other service providers. For example, the networks 112 may include another core network connected to one or more RANs, which may employ the same RAT as the RAN 104 or a different RAT.

[0031] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities, i.e., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links. For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with the base station 114a, which may employ a cellular -based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0032] FIG. IB is a system diagram of an example WTRU 102. As shown in FIG. IB, the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive element 122, a speaker/microphone 124, a keypad 126, a display /touchp ad 128, non-removable memory 130, removable memory 132, a power source 134, a global positioning system (GPS) chipset 136, and other peripherals 138. It will be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with an embodiment.

[0033] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits (ASICs), Field Programmable Gate Array (FPGAs) circuits, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit/receive element 122. While FIG. IB depicts the processor 118 and the transceiver 120 as separate components, it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0034] The transmit/receive element 122 may be configured to transmit signals to, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, the transmit/receive element 122 may be an antenna configured to transmit and/or receive RF signals. In another embodiment, the transmit/receive element 122 may be an emitter/detector configured to transmit and/or receive IR, UV, or visible light signals, for example. In yet another embodiment, the transmit/receive element 122 may be configured to transmit and receive both RF and light signals. It will be appreciated that the transmit/receive element 122 may be configured to transmit and/or receive any combination of wireless signals.

[0035] In addition, although the transmit/receive element 122 is depicted in FIG. IB as a single element, the WTRU 102 may include any number of transmit/receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit/receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0036] The transceiver 120 may be configured to modulate the signals that are to be transmitted by the transmit/receive element 122 and to demodulate the signals that are received by the transmit/receive element 122. As noted above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers for enabling the WTRU 102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, for example.

[0037] The processor 118 of the WTRU 102 may be coupled to, and may receive user input data from, the speaker/microphone 124, the keypad 126, and/or the display /touchp ad 128 (e.g., a liquid crystal display (LCD) display unit or organic hght-emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker/microphone 124, the keypad 126, and/or the display /touch ad 128. In addition, the processor 118 may access information from, and store data in, any type of suitable memory, such as the non-removable memory 130 and/or the removable memory 132. The nonremovable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 may access information from, and store data in, memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0038] The processor 118 may receive power from the power source 134, and may be configured to distribute and/or control the power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and the like.

[0039] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to, or in lieu of, the information from the GPS chipset 136, the WTRU 102 may receive location information over the air interface 116 from a base station (e.g., base stations 114a, 114b) and/or determine its location based on the timing of the signals being received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by way of any suitable location-determination method while remaining consistent with an embodiment.

[0040] The processor 118 may further be coupled to other peripherals

138, which may include one or more software and/or hardware modules that provide additional features, functionality and/or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photographs or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands free headset, a Bluetooth® module, a frequency modulated (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, and the like.

[0041] FIG. 1C is a system diagram of the RAN 104 and the core network 106 according to an embodiment. As noted above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also be in communication with the core network 106.

[0042] The RAN 104 may include eNode-Bs 140a, 140b, 140c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 140a, 140b, 140c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 140a, 140b, 140c may implement MIMO technology. Thus, the eNode-B 140a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0043] Each of the eNode-Bs 140a, 140b, 140c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink and/or downlink, and the like. As shown in FIG. 1C, the eNode-Bs 140a, 140b, 140c may communicate with one another over an X2 interface.

[0044] The core network 106 shown in FIG. 1C may include a mobility management entity gateway (MME) 142, a serving gateway 144, and a packet data network (PDN) gateway 146. While each of the foregoing elements are depicted as part of the core network 106, it will be appreciated that any one of these elements may be owned and/or operated by an entity other than the core network operator.

[0045] The MME 142 may be connected to each of the eNode-Bs 140a,

140b, 140c in the RAN 104 via an Si interface and may serve as a control node. For example, the MME 142 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation/deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 142 may also provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM or WCDMA.

[0046] The serving gateway 144 may be connected to each of the eNode

Bs 140a, 140b, 140c in the RAN 104 via the Si interface. The serving gateway 144 may generally route and forward user data packets to/from the WTRUs 102a, 102b, 102c. The serving gateway 144 may also perform other functions, such as anchoring user planes during inter-eNode B handovers, triggering paging when downlink data is available for the WTRUs 102a, 102b, 102c, managing and storing contexts of the WTRUs 102a, 102b, 102c, and the like.

[0047] The serving gateway 144 may also be connected to the PDN gateway 146, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0048] The core network 106 may facilitate communications with other networks. For example, the core network 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. For example, the core network 106 may include, or may communicate with, an IP gateway (e.g., an IP multimedia subsystem (IMS) server) that serves as an interface between the core network 106 and the PSTN 108. In addition, the core network 106 may provide the WTRUs 102a, 102b, 102c with access to the networks 112, which may include other wired or wireless networks that are owned and/or operated by other service providers.

[0049] Other network 112 may further be connected to an IEEE 802.11 based wireless local area network (WLAN) 160. The WLAN 160 may include an access router 165. The access router may contain gateway functionality. The access router 165 may be in communication with a plurality of access points (APs) 170a, 170b. The communication between access router 165 and APs 170a, 170b may be via wired Ethernet (IEEE 802.3 standards), or any type of wireless communication protocol. AP 170a is in wireless communication over an air interface with WTRU 102 d.

[0050] Referring now to FIG. 2, a diagram illustrating relay architecture is shown. Relaying is a feature in the IEEE 802.11ah WLAN system. The general design of the relay is stated in the IEEE 802.11ah standard, incorporated herein by reference. Relay 202, Relay 204, and Relay 206 may be relays and may include a relay STA, a relay AP, and a relay function. The relay STA 208, relay AP 210, and relay function 212 of Relay 204 are shown in FIG. 2. The relay STAs of Relay 202 and Relay 204 may be associated with a root AP 214. The relay STA of Relay 206 may be associated with the relay AP of Relay 202.

[0051] STA 216 may be a non-AP STA associated with the relay AP of

Relay 202. STA 218 and STA 220 may be non-AP STAs associated with the relay AP of Relay 206. STA 222 and STA 224 may be non-AP STAs associated with the relay AP 210 of Relay 204. Frames from STA 216 may be forwarded via the relay function of Relay 202 from the relay AP to the relay STA and then to the root AP 214. Similarly, frames from the root AP 214 may be forwarded to STA 216 via the relay STA, the relay function and the relay AP of Relay 202. Similar forwarding may be done by Relay 206 and Relay 202 in sequence to handle frames from STA 218 and STA 220 relaying multiple times to or from the root AP.

[0052] Under one Root AP, a first STA may be an upstream STA to a second STA if a frame sent to the Distribution System (DS) by the second STA is forwarded by the first STA. In this case, the second STA may be a downstream STA to the first STA.

[0053] Referring now to FIG. 3, a diagram of a relay element 300 is shown. A relay AP may indicate a root AP to which it is directly or indirectly associated by including a root AP basic service set (BSS) identification as a RootAP BSSID 302 in its relay element 300. The Element ID 304 may be used to identify the relay element 300. The Length 306 may identify the length of the relay element 300. This may be used in the future if new fields are added to the relay element 300. A relay STA may use this value to skip the unrecognized fields and jump directly to the next element. The Relay Control 308 may be used to indicate the presence of the RootAP BSSID 302.

[0054] The IEEE 802.11ah standard may specify how a root AP, or a relay STA, determines how to forward a received frame to a downstream STA, or the determination may be implementation specific. A MAC service tuple passed to a root AP from the DS, or received at a relay STA via the wireless medium (WM), may be examined by the relay function. If the destination address (DA) matches the address of the relay AP or an associated non-AP STA, it may be delivered using legacy (non-relay) methods. Otherwise, the included MAC Service Data Unit (MSDU) is forwarded via the WM to the associated relay STA using either a four-address frame format or an A-MSDU format. The associated relay STA may have most recently included the MSDU's DA in a reachable address (RA) element.

[0055] The IEEE 802.11ah standard may further specify how a relay

STA informs an upstream relay AP of the identities of the STAs that are downstream. The downstream STAs may be either relay STAs or non-AP STAs. A relay STA may send a reachable address update frame in a reassociation request frame to the AP to which the relay STA is associating. The reachable address update frame may contain a reachable address element, which itself may contain a current list of reachable address fields..

[0056] Referring now to FIG. 4A, a diagram of a reachable address update element 400 is shown. An Element ID field 402 and a Length field 404 may identify the reachable address element 400. An Initiator MAC Address field 406 may indicate the MAC address of the relay STA that transmits the reachable address element 400. A relay STA may set the Initiator MAC Address Field 406 to its own MAC address. An Address Count field 408 may be an integer representing the number of addresses in one or more reachable address fields 410. The one or more reachable address fields 410 may indicate the MAC addresses that can be reached through the relay STA.

[0057] Referring now to FIG. 4B, a diagram illustrating a reachable address field 412 of the one or more reachable address fields 410 is shown. An Add/Remove subfield 414 may be set to 1 if the MAC address is the address of a new STA joining the relay. The Add/Remove subfield 414 may be set to 0 if the MAC address is the address of a STA leaving the relay. A Relay Capable subfield 416 may be set to 1 if the STA is relay capable, otherwise it may be set to 0. A MAC Address subfield 418 may be set to the MAC address of the STA that joins or leaves the BSS.

[0058] The reachable address update element 400 may contain a current list of reachable addresses to which it is associated when one or more of the following conditions occur. The reachable address update element 400 may be sent when a new non-AP STA associates with the relay AP of the relay. The reachable address update element 400 may be sent when a non-AP STA is disassociated or deauthenticated from the relay AP of the relay. The reachable address update element 400 may be sent when a reachable address update frame is received at the relay AP of the relay. A relay STA generating a reachable address element 400 under the first two conditions may set the Initiator MAC Address field 406 of the reachable address update element 400 to its own MAC address.

[0059] A relay STA may set the Add/Remove subfield 414 to 1 if the STA is identified by the MAC Address subfield 418 is associated to the relay AP of the relay. The relay STA may set the Add/Remove subfield 414 to 0 if the STA identified by the MAC Address subfield 418 disassociated from the relay AP of the relay. A root AP may update the DS upon receipt of a reachable address update frame.

[0060] In an IEEE 802.11 WLAN system, there may one or more types of STA mobility within a network. One type of STA mobility may be no- transition. In this type, two subclasses may be identified: static and local movement. In the static subclass, there may be no motion. In the local movement subclass, there may be movement within the physical (PHY) range of the communicating STAs, such as movement within a basic service area (BSA). Another type of mobility may be a BSS-transition, which may be defined as STA movement from one BSS in one extended service set (ESS) to another BSS within the same ESS. A fast BSS transition may establish the state necessary for data connectivity before reassociation of the STA rather than after reassociation.

[0061] Another type of mobility may be ESS-transition, which may be defined as STA movement from a BSS in one ESS to a BSS in a different ESS. Maintenance of upper-layer connections may not be guaranteed, and disruption of service may occur in this mobility type.

[0062] The Fast Transition (FT) protocol may provide a mechanism for a

STA to perform a BSS transition between APs in a robust security network (RSN) or when quality-of-service (QoS) admission control is enabled in the ESS. The different association services may support the different categories of mobility.

[0063] Under the IEEE 802.1 lah standard, when a STA moves from one relay (API) to another relay (AP2) under the same root AP, it may be considered as a BSS-transition as defined above. This may be a BSS-transition because relay APs under the root AP may have the same service set identifier (SSID). A relay AP may use the same SSID as the AP to which its relay STA is associated.

[0064] When a STA moves away from the BSS in the case of BSS- transition, it may not perform a disassociation from the old BSS. Instead, a reassociation procedure may be performed in the new BSS. The association may be sufficient for no-transition MSDU delivery between STAs. Additional functionality may be needed to support BSS-transition mobility. The additional required functionality may be provided by a reassociation service in the Distribution System Service (DSS).

[0065] The reassociation service may be invoked to move a current association from one AP to another. This may keep the DS informed of the current mapping between an AP and a STA as the STA moves from BSS to BSS within an ESS. Reassociation may also enable the changing of association attributes of an established association while the STA remains associated with the same AP. Reassociation may be initiated by the non-AP STA. [0066] During a fast BSS transition a Robust Security Network

Association (RSNA) may be moved during reassociation. Therefore, if FT is not used, the old RSNA may be deleted and a new RSNA may be constructed.

[0067] A STA may disassociate with the AP when the STA leaves the network. The network may not need to rely on the STA informing the AP of the departure. The STA may attempt to disassociate when it leaves the network. However, the MAC protocol may not depend on the STA invoking the disassociation service. MAC management may be designed to accommodate loss of communication with an associated STA.

[0068] A max idle period may be a time period during which a STA can refrain from transmitting frames to its associated AP without being disassociated. The max idle period may be indicated in a Max Idle Period field of a BSS Max Idle Period element. A non-AP STA may be considered inactive if an associated AP has not received a Data frame, PS-Poll frame, or Management frame of a frame exchange sequence initiated by the STA for a time period greater than or equal to the time specified by the Max Idle Period field.

[0069] If an Idle Options field of a BSS Max Idle Period element specifies the use of protected keep-alive frames, then the AP may disassociate the STA if no protected frames are received from the STA for a period indicated by the Max Idle Period field of the BSS Max Idle Period element. If the Idle Options field allows unprotected or protected keep-alive frames, then the AP may disassociate the STA if no protected or unprotected frames are received from the STA for a duration indicated by the Max Idle Period field of the BSS Max Idle Period element.

[0070] The AP may be able to set the BSS Max Idle Period to a long value, such as one or more days. In a STA, two MSBs of the Max Idle Period field may contain a Unified Scaling Factor subfield and a remaining 14 bits may contain an Unsealed Interval subfield. A Listen Interval field may be carried in a PPDU. In a STA, the value of a BSSMaxIdlePeriod parameter used by MAC Layer Management Entity (MLME) primitives may be measured in periods of 1000 time units (TUs). The BSSMaxIdlePeriod parameter may be equal to the value of the Unsealed Interval subfield multiplied by a scaling factor that corresponds to the value indicated in the Unified Scaling Factor subfield. The Unified Scaling Factor subfield encoding may be defined in the IEEE 802.11ah standard. With the new element, the max idle period may be set up to approximately 5 years.

[0071] A relay may use implicit acknowledgment methods. A STA that has enabled an implicit ACK procedure may consider a received SlG_SHORT/SlG_LONG PPDU as a successful acknowledgement of a previously transmitted MPDU that was carried in an SlG_SHORT/SlG_LONG PPDU when the STA is a non-AP STA associated to a relay AP and the following conditions are satisfied. A PHY-RXSTART.indication primitive that corresponds to the received PPDU may be detected within an AckTimeout interval that started as a result of the previously transmitted MPDU. A RXVECTOR parameter PARTIAL_AID may be equal to the PARTIAL_AID that corresponds to the BSSID of the root AP or the PARTIAL_AID may be equal to 0 and the PPDU may contain a Request to Send (RTS) frame with a reachable address equal to the BSSID of the root AP. The RXVECTOR parameter UPLINK jNDICATION may be equal to 1.

[0072] A STA attached to a relay may use the PARTIAL_AID derived from the root AP BSSID as an indication that the preceding UL frame to the relay has been successfully received. The PARTIAL_AID may be in the PHY header of a frame immediately after its own uplink frame to the relay.

[0073] As described above, a STA associated with a relay AP may be assigned a large value of max idle period. The STA may be asleep when it is not in active communication with the relay AP, for example, during the time outside of Target Wake Time (TWT) service period. When the STA wakes up, it may have been moved outside the communication range of the associated relay AP, but it may find another relay AP in the same ESS. In this situation, the STA may perform re-authentication and re-association with a new target AP. For a relay, there may be a list (e.g., a forwarding database) that may contain a next hop relay for the reachable address based on the procedures described above. [0074] Under normal circumstances, the target AP may update the DS after a successful re- association. However, a problem may occur when the movement described above is under the same root AP. For example, a first relay AP (relay API) and a second relay AP (relay AP2) may be directly or indirectly associated with a root AP.

[0075] A first station (STAl) may originally be associated with relay

API. The STAl may wake up from an idle period to find itself under the coverage of relay AP2, which may be in the same ESS under the same root AP. STAl may perform reassociation with relay AP2. As described above, relay AP2 may send a reachable address update frame to the root AP. The root AP may update its forwarding database pointing, pointing STAl to relay AP2. STAl may perform communication with a Machine-Type Communication (MTC) server and may go back to sleep.

[0076] The root AP may not receive or forward any data frames from or to STAl if there are no data packets generated after reassociation. Because it is a BSS transition, an L3 procedure may not be required. STA authentication procedures may be performed at relay AP2 and traffic may not be generated beyond the associated relay AP2 in accordance with the FT protocol described above. Even if FT is not used before reassociation with the relay AP2 (i.e., a full authentication is performed), the EAP exchange may be relayed by the relay AP2. The traffic may not appear to the root AP as STAl generated frames. Because of this, the root AP may not rely on authentication messages to determine whether STAl has undergone BSS transition.

[0077] If STAl is configured with a long max idle period, relay API may think STAl is still associated. After a while, sometime before the expiration of the max idle period for STAl, a second station (STA2) may join the BSS of relay API. As described above, relay API may send a reachable address update frame to the root AP containing the current list of reachable addresses (i.e., the addresses of STAl and STA2). The root AP may update the forwarding database, pointing STAl back to relay API. After a period of time, a server may initiate communication to STAl. The root AP, based on information from the forwarding database, may forward packets to relay API. [0078] If relay API cannot reach STAl, it may locally disassociate with

STAl. As described above, relay API may send a reachable address update frame to root AP to remove STAl from the reachable address. The root AP may update the DS to reflect that STAl is no longer reachable. The root AP may no longer forward packets with a DA corresponding to STAl's MAC address to any of its relay APs.

[0079] As described above, the reachable address updating procedure may face issues when a STA transitions from one relay AP to another relay AP when they are both associated (directly or indirectly) with the same root AP.

[0080] As shown in FIG. 2, there may be more than two hops between a

STA and the root AP. The implicit acknowledgement procedure described above may only work in the case that the STA receiving the implicit acknowledgement and the root AP are two hops away. Issues may arise with implicit ACK procedures if a relay is not directly associated with a root AP.

[0081] Although the reachable address update frame may be a protected management frame, a relay STA with a compromised upper layer may utilize its lower layer RSNA credentials to perform an attack. If a rogue relay STA performs a reachable address update with a relay network, the rogue relay STA may potentially divert packets from reaching their intended destinations. Furthermore, if a STA associates with rogue relay AP, the rogue relay AP may act as a middleman to eavesdrop or tamper with the STAs data. Detection of the attack may be important.

[0082] A process of differential reachable address updating may be used to improve the reachable address update procedures for relays. A relay STA may send a frame that contains a reachable address update element 400 to the AP to which it is associated when one or more of the following conditions occur. The frame may be sent when a new non-AP STA associates with the relay AP of the relay. The frame may be sent when a non-AP STA is disassociated or deauthenticated from the relay AP of the relay. The frame may be sent when a reachable address update frame is received at the relay AP of the relay. The relay STA may send differential reachable address updates to its upstream AP. [0083] Referring now to FIG. 5 a diagram illustrating a differential reachable address update is shown. This differential reachable address update procedure may be performed if a new non-AP STA 502 associates with a first relay 504. The first relay 504 may send the reachable address update frame to an upstream second relay 506. Rather than sending a reachable address update containing a list of all STAs associated with the first relay 504, the first relay 504 may send a reachable address update that only contains information about the newly associated non-AP STA 502. This may prevent upstream APs from rewriting their forwarding databases with erroneous information about routing information for STAs that may have already associated/disassociated from the first relay 504. For example, an old non-AP STA 510 may be currently associated with a third relay 512 and may have not actively disassociated with the first relay 504. Because the first relay 504 may only send a reachable address update frame with information about the new non-AP STA 502, it may not cause the second relay 506 to rewrite its forwarding database, which may have been previously updated after receiving a reachable address update frame from the third relay 512 upon association with the old non-AP STA 510.

[0084] The reachable address update frame may contain the address of the newly associated non-AP STA 502. This may be done by setting the Add/Remove subfield 414 to 1 in the reachable address field 412. If the address in the reachable address update frame is marked as add, then an entry may be added/updated to the forwarding database indicating the address is to be forwarded to the first relay 504. The second relay 506, and subsequent upstream APs including a root AP 508, may perform a comparison of the received reachable address update frame and its own forwarding database. If the address is marked as add and the first relay 504 is different than what is listed as the forwarding relay of the non-AP STA 510 in the forwarding database of the second relay 506, the second relay 506 may send a reachable address update frame to an upstream AP containing only the changed entries. Otherwise, no action may be taken by the second relay 506. As shown in FIG. 5, the second relay 506 may send the reachable address update frame with the address of the newly associated STA 502 to the root AP 508. For relay systems with multiple hops, the reachable address update frame may contain an identity of the relay that initiated the reachable address update.

[0085] Referring now to FIG. 6, a diagram illustrating a differential reachable address update is shown. This differential reachable address update procedure may be performed if a non-AP STA 606 is implicitly disassociated or deauthenticated from the first relay 602. The first relay 602 may send the reachable address update frame to an upstream second relay 604. Rather than sending a reachable address update containing a list of all ST As associated with the first relay 602, the first relay 602 may send a reachable address update that only contains information about the stale non-AP STA 606.

[0086] The reachable address update frame may contain the address of the newly de-associated/de-authenticated STA 606 with the add/remove subfield set to 0. The second relay 604, (and subsequent upstream APs including a root AP 608), may perform a comparison of the received reachable address update frame and its own forwarding database. If the address is marked as remove and the first relay 602 is listed as the forwarding relay of the non-AP STA 606 in the forwarding database of the second relay 604, the second relay 604 may send a reachable address update frame to an upstream AP containing only the changed entries. Otherwise, no action may be taken by the second relay 604. As shown in FIG. 6, the forwarding database of the second relay 604 already has the non-AP STA 606 associated with the third relay 610, so a reachable address update frame is not sent to the root AP 608. It should be noted that, the first relay 602 may also take no action if it has no recent radio contact with the disassociated non-AP STA 606. For relay systems with multiple hops, the reachable address update frame may contain an identity of the relay that initiated the reachable address update.

[0087] When a relay STA re-associates with an AP, the co-located relay

AP may disassociate with all STAs, or it may use one or a combination of the following approaches for conveying reachable addresses of the downstream STAs. [0088] One or more procedures may be used to signal the time of a last radio contact. A relay STA may include a last radio contact time with the reachable address update for each address. If the forwarding database of a receiver already contains this address, it may compare the received timestamp with a timestamp in the database. If the received timestamp is newer or the address does not exist in the forwarding database, then the forwarding database may be updated.

[0089] The relay AP and/or root AP may record the last radio contact time in its forwarding database, based on the received reachable address update for the address, if the relay STA having this address is not directly associated with the relay AP and/or root AP.

[0090] The relay AP and the relay STA may be co-located but may belong to a different BSS and may not have the same clock. A conversion of time stamp may be needed when forwarding the reachable address update elements 400. Alternatively a relative timestamp may be used. The relative timestamp may indicate the duration between the last radio contact and the time when the message containing the reachable address update element 400 is sent.

[0091] A STA may initiate the reachable address update after joining or before leaving a BSS. A STA, either a non-AP STA or a relay STA, may initiate a reachable address update for itself to its AP. The AP may then forward the reachable address update upstream and may aggregate updates from multiple STAs.

[0092] If the STA is a relay and re-associates with an AP, it may send a broadcast message (or unicast messages to all associated STAs) in the BSS of its relay AP indicating the need for an reachable address update. The indication may be passed downstream across multiple relays. A downstream STA may receive the indication and initiate a reachable address update, possibly within a window of random delays. If the disassociation of a downstream STA is initiated by a relay AP, the relay AP may send the reachable address update on behalf of the disassociated STA if there is an acknowledgment from the STA. [0093] An aging mechanism may be applied to an reachable address entry, such that the reachable address entry is removed after a duration of time in which data frames with a source address (SA) matching the address are not received. The reachable address entry may be removed after a duration of time in which an reachable address update is not received for the address.

[0094] The reachable address may be removed from an upstream STA. A relay AP and/or root AP that receives an address update from a different downstream STA than the forwarding relay recorded in the forwarding database may send a message downstream to the original forwarding relay STA to remove the reachable address entry of the STA. The message may also include the MAC address of the initiator of the reachable address update. The receiving relay may send the message downstream if its forwarding database indicates there is another relay downstream.

[0095] The receiver of the message may remove the reachable address from its forwarding database. The relay may no longer include this address in the reachable address update sent upstream. The relay may include the address again if there is a reachable address update from a downstream STA that adds the address back, or if the STA with this address associates with the relay.

[0096] Referring now to FIG. 7, a diagram illustrating a root AP- initiated removal of an outdated reachable address is shown. The reachable address element 400 in the reachable address update frame may contain the initiator MAC address (i.e., a relay AP's MAC address). Based on the information received in the reachable address update frames, a root AP 702 may keep track of the RAs, the STAs, and their associated initiator MAC addresses.

[0097] For example, for a STA 710, the root AP 702 may detect the associated initiator MAC address has changed either based on a newly received reachable address update frame or if STA 710 is now directly associated with the root AP 702. The root AP 702 may send a message that contains the "old initiator MAC address" for a relay AP 706 and "STA MAC address" for STA 710 to indicate the removal of the MAC address of the STA 710 along the old path.

[0098] The message may be addressed to an immediate downstream relay 704 on the path to the "old initiator MAC address." This immediate downstream receiving relay AP 704 may forward the message and may update its forwarding table based on the message. The receiving relay AP 704 may read the message to find the "old initiator MAC address."

[0099] Based on the forwarding table entry in the receiving relay AP

704, the receiving relay AP 704 may send the same message to the immediate next hop relay AP 706 on the path to the "old initiator MAC address." If there is another entry for the "STA MAC address" of STA 710 that indicates forwarding to an address other than the immediate next hop relay AP 706 on the path to the "old initiator MAC address," such as a relay 708, the receiving relay AP 704 may remove the forwarding entry that uses the immediate next hop relay AP 706 on the path to the "old initiator MAC address." The receiving relay AP 704 may also remove the forwarding entry if the STA with "STA MAC address" is now currently directly associated with the receiving relay 704 AP (i.e., the relay AP 704 is the initiator of the most recent reachable address update).

[0100] The receiving relay AP 704 may send an acknowledgement to an upstream relay (not shown) or the root AP 702 following an action frame acknowledgement procedure. If the receiving relay AP 704 has the "STA MAC address" from STA 710 directly associated with itself and the MAC address of the receiving relay AP 704 is the "old initiator MAC address," it may implicitly disassociate with the STA 710. Alternatively, the receiving relay AP 704 may perform an "association check" as described below.

[0101] An intermediate relay may create a new forwarding entry after receiving a reachable address update frame for a STA that already has an old forwarding entry. Before the old entry is removed, which may be triggered by the message originating from root AP 702, the intermediate relay may forward the DL data to both downstream relays. [0102] The next hop relay AP 706 with the "old initiator MAC address" may send a frame, such as a Quality of Service (QoS) null frame, to trigger a response from the STA 710. If the next hop relay AP 706 does not receive a response, it may (implicitly) dis-associate the STA 710. If the STA 710 responds, the next hop relay AP 706 may send the reachable address update frame upstream to add the STA 710 back to the forwarding path leading to itself.

[0103] A relay/root AP may update its forwarding database based on a downstream STA forwarding an uplink data frame. More specifically, the update may be based on the SA (i.e., MAC address) of the data frame or the SA of the A-MSDU and the relay from which it received the uplink data frame. An aging mechanism may be applied to each address entry such that the address entry is removed after a certain time if data frames having a SA matching the address are not received. It should be noted that there may be no data/L3 traffic sent in the re-association process.

[0104] The following description may include efficient implicit ACK procedures for multi-hop relays. A relay AP may indicate in an element or frame, such as its relay element, an identification (ID) of its direct upstream AP. The ID may be a BSSID or partial AID. The direct upstream AP may be the AP to which its co-located relay STA is associated. The relay AP may include the above information in one or more of its beacon signals, probe response frames, reassociation frames, action frames, Action No ACK frames, management frames, control frames, data frames extensions, or MAC/PHY headers. The STAs associated with the relay AP may then extract information from the BSSID, such as information about the upstream AP that is 2 hops away.

[0105] Referring now to FIG. 8, a diagram of a first enhanced relay element 800, as described above, is shown. The first enhanced relay element 800 may contain an Element ID 802, a Length 804, a Relay Control 806, and an Upstream AP ID/BSSID 808. The Element ID 802 may be used to identify the first enhanced relay element 800. The Length 804 may identify the length of the first enhanced relay element 800. This may be used in the future if new fields are added to the first enhanced relay element 800. A relay STA may use this value to skip the unrecognized fields and jump directly to the next element. The Relay Control 806 may be used to indicate the presence of the Upstream AP ID/BSSID 808. The Upstream AP ID/BSSID 808 may be included in the enhanced relay element 800 instead of the root AP BSSID. For a relay AP that is directly associated with the root AP, the BSSID of the root AP may be included in the Upstream AP ID/BSSID 808 field.

[0106] Referring now to FIG. 9, a diagram of a second enhanced relay element 900, as described above, is shown. The second enhanced relay element 900 may contain an Element ID 902, a Length 904, a Relay Control 906, an Upstream AP ID/BSSID 908, and a Root AP BSSID 910. The Element ID 902 may be used to identify the second enhanced relay element 900. The Length 904 may identify the length of the second enhanced relay element 900. This may be used in the future if new fields are added to the second enhanced relay element 900. A relay STA may use this value to skip the unrecognized fields and jump directly to the next element. The Relay Control 906 may be used to indicate the presence of the Root AP BSSID 910. The Upstream AP ID/BSSID 908 may contain the partial AID or BSSID of the upstream AP. The Upstream AP ID/BSSID 908 and/or the RootAP BSSID 910 fields may be optional. The inclusion of the Upstream AP ID/BSSID 908 and/or RootAP BSSID 910 fields may be indicated by one or more indicators in the enhanced relay element 900, for example, by a Hierarchy Identifier subfield in the Relay Control 906 field.

[0107] Potential values and meanings of the Hierarchy Identifier subfield are shown in Table 1.

Hierarchy Meaning Presence of fields in Relay Identifier element

0 RootAP No Upstream AP

ID/BSSID or RootAP BSSID field is included in the Relay element

1 Relay AP that is directly Only RootAP BSSID field associated with the RootAP is included in Relay

element. No Upstream AP ID/BSSID is included in Relay element.

2 relay AP that relays frames Both Upstream AP

within the BSS ID/BSSID or RootAP identified by the BSSID BSSID field are included in contained in the the Relay element

RootAP BSSID field

3-127 Reserved

Table 1

[0108] The enhanced implicit ACK procedures may include one or more of the following steps. A relay AP may indicate its upstream AP and/or root AP in one or more frames, such as its relay element, beacon, Probe Response, Reassociation Response, NDP frames, or MAC/PLCP headers. The upstream AP and/or root AP may be indicated using one or more of its ID, partial AID and/or BSSID. The inclusion of the Upstream AP ID/BSSID and/or RootAP BSSID fields in the relay element may be indicated by the Hierarchy Identifier subfield in the Relay Control field of the Relay element. STAs may extract the ID/BSSID/Partial AID of the upstream AP from the relay element or any other element and/or frames that the relay AP uses to indicate its upstream AP and/or root AP.

[0109] If a STA has enabled the implicit ACK procedure, it may consider a received SlG_SHORT/SlG_LONG PPDU as a successful acknowledgement of a previously transmitted MPDU that was carried in an SlG_SHORT/SlG_LONG PPDU. The STA may be a non-AP STA or a relay STA associated with a relay AP. In this procedure, a PHY-RXSTART indication that corresponds to the received PPDU may be detected within an AckTimeout interval that started as a result of the previously transmitted MPDU. A RXVECTOR parameter PARTIAL_AID may be equal to the PARTIAL_AID that corresponds to the BSSID of the root AP or may be equal to the PAETIAL_AID that corresponds to the BSSID of the upstream AP of its relay AP. The PARTIAL_AID may be equal to 0 and the PPDU may contain a RTS frame with a reachable address equal to the BSSID of the root AP or the BSSID of the upstream AP of its relay AP. A RXVECTOR parameter UPLINK JUDICATION may be equal to 1.

[0110] As described above, a relay trusted by a root AP may insufficiently authenticate downstream relays. This may occur if the security settings of the relay are not implemented correctly or if the relay is using a weak security protocol. To address this, a relay may establish a direct security association with the root AP.

[0111] Upon association with a relay AP, a relay may perform an additional security association directly with the root AP. In other words, there may be an authentication by the root AP of the relay, which is more than one hop away from the root AP. The MPDU/MMPDU exchanges between the root AP and the relay may be encapsulated as MSDU data and may be transported via each hop.

[0112] When sending the reachable address update frame, the reachable address element 400 may be signed by a key obtained from the direct security association of the relay and the root AP. The reachable address update message may be encrypted and decrypted at each hop, visible to all intermediate relays. The intermediate relays may not modify the signed reachable address element 400.

[0113] When forwarding the reachable address update for a relay ST A, the route may be recorded as part of the reachable address update frame and signed by the relay using a key obtained from its own security association with the root AP. When the root AP receives the reachable address update, it may verify the recorded route and reachable address update element 400. If all signatures are verified, the root AP may contact each relay in the old recorded route using, for example, a relay-root AP direct security association, to remove the forwarding entry for the relay STA. The root AP may contact each relay in the new recorded route using, for example, a relay-root AP direct security association, to add the forwarding entry for the relay STA. If the recorded route or the reachable address element 400 cannot be verified by the root AP, no action may be taken and DL data to the relay STA may be forwarded via the old route.

[0114] Security may be verified using a signed token from a previous relay AP. A token may be sent from a root AP to a relay after it initiates a reachable address update for a relay STA associated with the relay. The relay may send the token signed with a key obtained from its security association with the root AP to the relay STA after completing the reachable address update. If the relay STA moves to a new relay, it may provide the new relay with the signed token. The new relay may send the signed token together with the reachable address update frame. This may allow the root AP to verify that the token is signed by the first relay.

[0115] If the token verification is not provided, for example, if there is a loss of power or a reboot of the relay STA before association to the second relay, the root AP may generate an MPDU to the relay STA via the old route. This may cause disassociation if the relay STA is not reachable via the first relay. The relay AP may only accept an update from the second relay after there is an update from the first relay removing the relay STA.

[0116] Although features and elements are described above in particular combinations, one of ordinary skill in the art will appreciate that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated in a computer- readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, a read only memory (ROM), a random access memory (RAM), a register, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD- ROM disks, and digital versatile disks (DVDs). A processor in association with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

CLAIMS What is claimed is:

1. A method for use in a relay of an IEEE 802.11 based wireless network, the method comprising:

storing a reachable address table in a forwarding database of the relay, wherein the reachable address table comprises routing information for one or more stations (STAs) and one or more other relays associated with the relay; determining a change in association of a STA with the relay;

updating the reachable address table to include routing information of the STA; and

sending a reachable address update to an upstream relay comprising updated routing information for only the STA with the changed association, such that the upstream relay does not overwrite routing information for the one or more STAs and the one or more other relays in its own forwarding database.

2. The method of claim 1, wherein the determining the change in association of the STA with the relay comprises the STA associating with the relay.

3. The method of claim 1, wherein the determining the change in association of the STA with the relay comprises the STA disassociating with the relay.

4. The method of claim 1, wherein the determining the change in association of the STA with the relay comprises the relay not receiving data frames from the STA after a period time.

5. The method of claim 1, wherein the relay and the upstream relay have a common root AP.

6. The method of claim 1, wherein the reachable address update further comprises a last radio contact time with the STA.

7. A method for use in a relay of an IEEE 802.11 based wireless network, the method comprising:

storing a reachable address table in a forwarding database of the relay, wherein the reachable address table comprises routing information for one or more stations (STAs) and one or more relays associated with the relay;

receiving a reachable address update from a downstream relay, wherein the reachable address update comprises updated routing information for only a downstream STA with a changed association status;

comparing the received updated routing information for the downstream STA in the reachable address update with routing information in the relay's reachable address table; and

determining whether to send an upstream reachable address update comprising the updating routing information for only the downstream STA to an upstream relay.

8. The method of claim 7, wherein the received updated routing information for the downstream STA comprises an indication to add or remove the downstream STA to the relay's reachable address table.

9. The method of claim 8, wherein the determining whether to send an upstream reachable address update to an upstream relay comprises:

sending the upstream reachable address update if the received updated routing information for the downstream STA comprises an indication to add the downstream STA and the compared routing information is different.

10. The method of claim 8, wherein the determining whether to send an upstream reachable address update to an upstream relay comprises:

sending the upstream reachable address update if the received updated routing information for the downstream STA comprises an indication to remove the downstream STA and the compared routing information is the same.

11. The method of claim 7, wherein the reachable address update comprises an identity of a downstream relay that initiated the reachable address update.

12. A method for use in a relay of an IEEE 802.11 based wireless network, the method comprising:

receiving, by the relay, a message from an upstream relay to initiate a removal of an outdated reachable address in a forwarding database, wherein the message comprises an old initiator media access control (MAC) address of a downstream relay and a station (STA) MAC address of a STA that is no longer associated with the downstream relay;

comparing the old initiator MAC address and the STA MAC address to routing information for the STA in the forwarding database; and

updating the forwarding database.

13. The method of claim 12, wherein the message is generated when a root AP receives a reachable address update and detects that a new initiator MAC address of a new downstream relay associated with the STA is different than the old initiator MAC address.

14. The method of claim 12, wherein the upstream relay is a root AP.

15. The method of claim 12, wherein the relay and the upstream relay have a common root AP.

16. The method of claim 12, further comprising:

forwarding the message to a next hop relay on a path to the downstream relay.

17. The method of claim 12, further comprising:

determining that there is an entry for the STA MAC address in the forwarding database indicating forwarding to a different relay than a next hop relay on a path to the downstream relay; and

removing the entry indicating forwarding to the next hop relay from the message; and

forwarding the message to the next hop relay indicating the removal of the STA from the next hop relay's forwarding database.

18. The method of claim 12, further comprising:

determining that the STA MAC address is directly associated with the relay; and

removing the entry indicating forwarding to a next hop relay on a path to the downstream relay from the message.

19. The method of claim 12, further comprising:

determining that the old initiator MAC address is a MAC address of the relay;

determining that the STA MAC address is directly associated with the relay; and

disassociating with the STA.

20. The method of claim 12, further comprising:

determining that the old initiator MAC address is a MAC address of the relay;

determining that the STA MAC address is directly associated with the relay; and

performing an association check with the STA to determine if the STA is still directly associated with the relay.

21. A method for use in a relay of an IEEE 802.11 based wireless network, the method comprising: receiving, by the relay, a reachable address update from a downstream relay, wherein the reachable address update comprises updated routing information for only a downstream station (STA) with a changed association status;

comparing an identity of the downstream relay with an identity of a forwarding associated with the downstream STA in a forwarding database of the relay; and

upon determining that the identity of the downstream relay and the identity of the forwarding relay are different, updating the forwarding database and sending a message to the forwarding relay indicating removal of the STA from the forwarding relay's forwarding database.

22. The method of claim 21, wherein the relay is a root AP.

23. The method of claim 21, wherein the relay and the downstream relay have a common root AP.

24. The method of claim 21, wherein the message is forwarded to one or more additional relays further downstream by the forwarding relay.