JP2016523036A - Method for selecting entities based on total link quality - Google Patents

Abstract

Systems, methods and means for a base station to determine link quality are disclosed. The base station (STA) can determine the quality of the path including the relay node by determining the link quality associated with each link of the path. The STA can receive a transmission indicating that the transmitting entity is a relay node. The transmission may indicate a first link quality associated with the link between the relay node and the root access point (AP). The STA can determine a second link quality associated with the link between (STA) and the relay node, for example, the STA can estimate the second link quality. The STA can determine the total link quality associated with the link from the STA to the relay node and from the relay node to the root AP. The STA can select related entities based on the total link quality.

Description

(Cross-reference of related applications)
This application claims the benefit of US Provisional Application No. 61 / 818,854, filed May 2, 2013, the disclosure of which is incorporated herein by reference.

  A multi-hop WiFi system can be used to improve the coverage and capacity of a single access point (AP) system. A multi-hop WiFi system can use relay APs and / or relay-type STAs that improve the channel conditions of the base station (STA), which can suffer from degraded channel conditions or coverage. In a relay-based WiFi system, an STA that receives a management frame (for example, a beacon frame or a probe response frame) from a relay AP cannot have sufficient information on all relay paths. The STA cannot have information on the link between the root AP and the relay AP, for example. The root AP cannot have information on the link between the relay AP and the destination STA, for example.

  This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. And not.

  Systems, methods and means for a base station to determine link quality are disclosed. For example, a base station (STA) can determine the quality of a path including a relay node by determining the link quality associated with each link of the path. The STA can receive a transmission indicating that the transmitting entity is a relay node. The transmission may be a beacon frame, a short beacon frame, a probe response frame, or the like. A relay device (eg, WTRU) can be a dedicated relay or other device (eg, a base station that functions as a relay, an access point (AP) that functions as a relay, or a base station that functions as an AP that functions as a relay). Non-base station). The transmission may indicate a first link quality associated with the link between the relay node and the root access point (AP). The root AP may be the destination node associated with the data transmitted by the STA. The STA can determine a second link quality associated with the link between the (STA) and the relay node, for example, the STA can estimate the second link quality by measuring a transmission metric. . The STA can determine the total link quality associated with the link from the STA to the relay node and from the relay node to the root AP.

  The STA can select related entities based on the total link quality. The STA can use the total link quality to determine whether to send data to the root AP via a relay node or to send data directly to the root AP. For example, the STA determines whether the total link quality meets the requirements (eg, whether the total link quality is better than the quality of the link between the STA and the root AP, the total link quality exceeds a threshold, such as an SNR threshold). Or not). The STA can make a selection to associate with the relay node to send to the root AP when the total link quality meets the requirements.

  The indication that the sending entity is a relay node may be explicit or implicit. An exemplary explicit indication that the sending entity is a relay node may be an explicit signal via an information element. An exemplary implicit indication that the transmitting entity is a relay node may be the first link quality present in the frame of transmission.

  A more detailed understanding may be obtained by the following description, given by way of example in conjunction with the accompanying drawings.

1 illustrates an example communication system. FIG. FIG. 2 illustrates an example wireless transmit / receive unit (WTRU). FIG. 2 illustrates an example wireless local area network (WLAN) device. It is a figure which shows the example of the relay architecture of IEEE802.11ah. It is a figure which shows the example of the downlink relay (for example, from AP to STA) using explicit ACK. It is a figure which shows the example of the uplink relay (for example, from STA to AP) using explicit ACK. It is a figure which shows the example of the relay operation | movement using implicit ACK. It is a figure which shows the example of transmission. It is a figure which shows the example of relay path selection in the case of a relay node and a source node. It is a figure which shows the example of a relay path selection in the case of 1 or several relay node and one source node. FIG. 6 is a diagram illustrating an example of a frame format for transmission in which a frame control field bit can indicate whether link quality between a relay and a root AP exists. FIG. 6 is a diagram illustrating an example of a frame format for transmission in which link quality between a relay and a root AP can be provided by an information element (IE). It is a figure which shows the example of the frame format of the flow control notification frame which can signal the address of a relay node. It is a figure which shows the example of the frame format of the flow control notification element format of the example flow control element shown in FIG. It is a figure which shows the example of the simplified flow control notification element format. It is a figure which shows the example of the frame format of the flow control notification frame which can signal the address of a destination node. It is a figure which shows the example of the frame format of the flow control notification element format of the example flow control element shown in FIG. It is a figure which shows the example of the transmission opportunity (TXOP) operation | movement using explicit ACK. It is a figure which shows the example of TXOP operation | movement using implicit ACK.

  A detailed description of the illustrated embodiments will now be described with reference to the various figures. It should be noted that this description provides detailed examples of possible implementations, but the details are exemplary and are in no way intended to limit the scope of this application. Further, the drawings may illustrate one or more message diagrams that are intended to be exemplary. Other embodiments may also be used. The order of the messages may be changed when appropriate. If not required, the message may be omitted and additional messages may be added.

  FIG. 1A is a diagram of an example communications system 100 in which one or more disclosed features may be implemented. For example, a wireless network (eg, a wireless network comprising one or more components of the communication system 100) has a QoS characteristic that bearers that extend beyond the wireless network (eg, beyond the walled garden associated with the wireless network). Can be assigned.

  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 allow multiple wireless users to access such content through sharing of system resources including wireless bandwidth. For example, the communication system 100 may include code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), etc. Multiple channel access methods can be used.

  As shown in FIG. 1A, a communication system 100 includes a plurality of WTRUs, eg, at least one wireless transmit / receive unit (WTRU), such as WTRUs 102a, 102b, 102c, and 102d, a radio access network (RAN) 104, a core network. 106, the public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, the disclosed embodiments may include any number of WTRUs, base stations, networks, and / or network elements. Recognize that you intend. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. As an example, the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and / or receive wireless signals, such as user equipment (UE), mobile stations, fixed or mobile subscriber units, pagers, cellular A telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a home appliance, and the like can be included.

  The communication system 100 may also include a base station 114a and a base station 114b. Each of the base stations 114a, 114b wirelessly interfaces with at least one of the WTRUs 102a, 102b, 102c, 102d to provide access to one or more communication networks, such as the core network 106, the Internet 110, and / or the network 112. It can be any type of device configured to facilitate. As an example, the base stations 114a, 114b may be base transceiver base stations (BTS), Node B, eNode B, home Node B, home eNode B, site controller, access point (AP), wireless router, etc. . Although base stations 114a, 114b are each shown as a single element, it should be appreciated that base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

  Base station 114a is part of RAN 104, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), radio network controller (RNC), relay node, etc. You can. Base station 114a and / or 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 be further divided into cell sectors. For example, the cell associated with the base station 114a can be divided into three sectors. Thus, in one embodiment, the base station 114a can include three transceivers, ie, one transceiver in each sector of the cell. In another embodiment, the base station 114a can use multi-input multi-output (MIMO) technology and thus can utilize multiple transceivers for each sector of the cell.

  Base stations 114a, 114b may be any suitable wireless communication link (eg, radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.) via an air interface 116. Can communicate with one or more of the WTRUs 102a, 102b, 102c, 102d. The air interface 116 may be established using any suitable radio access technology (RAT).

  More specifically, as described above, the communication system 100 may be a multiple access system and may use one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and so on. For example, the base station 114a and WTRUs 102a, 102b, 102c in the RAN 104 may establish a radio interface 116 using wideband CDMA (WCDMA), such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA). Can be implemented. 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).

  In another embodiment, the base station 114a and the WTRUs 102a, 102b, 102c can establish an evolved UMTS terrestrial radio that can establish an air interface 116 using Long Term Evolution (LTE) and / or LTE Advanced (LTE-A). Wireless technologies such as access (E-UTRA) can be implemented.

  In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may be IEEE 802.16 (ie, WiMAX (Worldwide Interoperability for Microwave Access), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, IS-2000 (Interim Standard 2000), IS-95 (Interim Standard 95), IS-856 (Interim Standard 856), global system for mobile communication (GSM (registered trademark)), extended data rate (EDGE) for GSM evolution, GSM EDGE (GERAN), etc. Wireless technology can be implemented.

  The base station 114b of FIG. 1A may be, for example, a wireless router, home Node B, home eNode B, or access point, facilitating wireless connectivity in local areas such as work, home, car, campus, etc. Any RAT suitable for doing so can be used. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 that establishes a wireless local area network (WLAN). In another embodiment, the base station 114b and the WTRUs 102c, 102d can implement a radio technology such as IEEE 802.15 establishing a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d can utilize a cell-based RAT (eg, WCDMA), CDMA2000, GSM, LTE, LTE-A, etc. to establish a pico cell or femto cell. As shown in FIG. 1A, the base station 114b can connect directly to the Internet 110. Therefore, the base station 114 b does not need to access the Internet 110 via the core network 106.

  The RAN 104 may be any type of network configured to provide voice, data, application, and / or VoIP (voice over internet protocol) services to one or more of the WTRUs 102a, 102b, 102c, 102d. It can communicate with the core network 106. For example, the core network 106 can provide call control, billing services, mobile location based services, prepaid phone calls, Internet connectivity, video delivery, etc., and / or perform high level security functions such as user authentication. Although not shown in FIG. 1A, it should be appreciated that the RAN 104 and / or core network 106 may be in direct or indirect communication with other RATs using the same RAT as the RAN 104 or a different RAT. For example, in addition to being connected to a RAN 104 that can utilize E-UTRA radio technology, the core network 106 can also communicate with another RAN (not shown) that uses GSM radio technology.

  The core network 106 may also function 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 a circuit switched telephone network that provides legacy voice telephone service (POST). The Internet 110 is a global network of interconnected computer networks and devices that use common communication protocols such as Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Internet Protocol (IP) in the TCP / IP Internet Protocol Suite. System can be included. Network 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, the network 112 can include another core network connected to one or more RANs, which can use the same RAT as the RAN 104 or a different RAT.

  Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capability, i.e., the WTRUs 102a, 102b, 102c, 102d communicate with different wireless networks via different wireless links. A plurality of transceivers can be included. For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that can use cell-based radio technology and a base station 114b that can use IEEE 802 radio technology.

  FIG. 1B shows an exemplary wireless transmission / reception unit, WTRU 102. The WTRU 102 may be used in one or more of the communication systems described herein. As shown in FIG. 1B, the WTRU 102 includes a processor 118, transceiver 120, transmit / receive element 122, speaker / microphone 124, keypad 126, display / touchpad 128, non-removable memory 130, removable memory 132, power supply 134, all A global positioning system (GPS) chipset 136 and other peripherals 138 may be included. It should be appreciated that the WTRU 102 may include any sub-combination of the above-described elements while remaining consistent with the embodiments.

  The processor 118 may be a general purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC). ), Field programmable gate array (FPGA) circuits, other types of integrated circuits (ICs), state machines, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to the transceiver 120 and the transceiver can be coupled to the transmit / receive element 122. 1B depicts the processor 118 and the transceiver 120 as separate components, it should be appreciated that the processor 118 and the transceiver 120 may be combined in an electronic package or chip.

  The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (eg, base station 114a) via 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 optical signals. It should be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

  Further, although the transmit / receive element 122 is shown in FIG. 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may use MIMO technology. Accordingly, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (eg, multiple antennas) that transmit and receive wireless signals over the air interface 116.

  The transceiver 120 may be configured to modulate the signal transmitted by the transmit / receive element 122 and demodulate the signal received by the transmit / receive element 122. As described above, the WTRU 102 may have multi-mode capability, and thus the transceiver 120 may be configured to allow multiple WTRUs 102 to communicate via multiple RATs, such as, for example, UTRA and IEEE 802.11. Of transceivers.

  The processor 118 of the WTRU 102 is coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (eg, a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit) from which the user. Input data can be received. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Further, processor 118 may access information from and store data in any suitable type of memory, such as non-removable memory 130 and / or removable memory 132. Non-removable memory 130 may include random access memory (RAM), read only memory (ROM), hard disk, or other types of memory storage devices. The removable memory 132 may include a subscriber identification module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, the processor 118 can access information from and store data in memory that is not physically located on the WTRU 102, such as on a server or home computer (not shown).

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

  The processor 118 may also be coupled to a GPS chipset 136 that may be configured to provide location information (eg, longitude and latitude) regarding the current location of the WTRU 102. As an addition or alternative to information from the GPS chipset 136, the WTRU 102 may receive location information via the air interface 116 from a base station (eg, base stations 114a, 114b) and / or two or more nearby The position of the WTRU can be determined based on the timing of the signal received from the base station. It should be appreciated that the WTRU 102 can obtain location information by any suitable location determination method while remaining consistent with the embodiment.

  The processor 118 is further 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. obtain. For example, the peripheral device 138 includes an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photo or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth (registered trademark) module. , Frequency modulation (FM) wireless units, digital music players, media players, video game player modules, Internet browsers, and the like.

  FIG. 1C illustrates an exemplary wireless local area network (WLAN) device. One or more of the devices can be used to implement one or more features described herein. A WLAN may include, but is not limited to, an access point (AP) 102, a base station (STA) 110, and a STA 112. STAs 110 and 112 may be associated with AP 102. A WLAN may be configured to implement one or more protocols of the IEEE 802.11 communication standard, which may include channel access schemes such as DSSS, OFDM, OFDMA, etc. The WLAN can operate in modes such as infrastructure mode, ad hoc mode, and the like.

  A WLAN operating in infrastructure mode may comprise one or more APs that communicate with the associated one or more STAs. The AP and STAs associated with the AP may comprise a basic service set (BSS). For example, the AP 102, the STA 110, and the STA 112 may include a BSS 122. An extended service set (ESS) may comprise one or more APs (with one or more BSSs) and STAs associated with the APs. The AP can access and / or interface to a distributed system (DS) 116, which can be wired and / or wireless and can carry traffic to and / or from the AP. Traffic to a WLAN STA originating from outside the WLAN may be received at the WLAN AP, which can send traffic to the WLAN STA. Traffic originating from the WLAN STA and destined for the outside of the WLAN, for example, the server 118, is sent to the WLAN AP, and the AP sends the traffic to the destination, for example, the network 114 sent to the server 118 via the DS 116. Can be sent out. Traffic between STAs in a WLAN may be sent via one or more APs. For example, a source STA (eg, STA 110) may have traffic destined for a destination STA (eg, STA 112). The STA 110 can send traffic to the AP 102, and the AP 102 can send the traffic to the STA 112.

  The WLAN can operate in an ad hoc mode. An ad hoc mode WLAN may be referred to as an independent basic service set (BSS). In an ad hoc mode WLAN, STAs can communicate directly with each other (eg, STAs 110 can communicate with STAs 112 without using communication routed through an AP).

  An IEEE 802.11 device (eg, IEEE 802.11 AP in a BSS) can use a beacon frame that announces the presence of a WLAN network. An AP, such as AP 102, can transmit a beacon on a channel, eg, a fixed channel, such as a main channel. The STA can establish communication with the AP using a channel, such as a main channel.

  The STAs and / or APs can use a Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) channel access mechanism. In CSMA / CA, STAs and / or APs can sense the main channel. For example, if the STA has data to transmit, the STA can sense the main channel. When the main channel is detected to be busy, the STA can back off. For example, a WLAN or portion thereof may be configured such that one STA can transmit at a given time, eg, a given BSS. Channel access can include RTS and / or CTS signaling. For example, a request to send (RTS) frame that can be sent by a sending device and a clear to send (CTS) frame that can be sent by a receiving device can be exchanged. For example, if the AP has data to send to the STA, the AP can send an RTS frame to the STA. If the STA is ready to receive data, the STA can respond with a CTS frame. While the AP initiating the RTS can send its data, the CTS frame can include a time value that can alert other STAs not to access the media. Upon receiving the CTS frame from the STA, the AP can send data to the STA.

  Devices can reserve spectrum through a network allocation vector (NAV) field. For example, in an IEEE 802.11 frame, the NAV field can be used to reserve a channel for a period of time. The STA that wants to transmit data can set the NAV at a time when it can expect to use the channel. When the STA sets the NAV, the NAV may be set to the associated WLAN or a subset thereof (eg, BSS). Other STAs can count down to zero NAV. When the counter reaches a value of zero, the NAV functionality can indicate to other STAs that the channel is currently available.

  A WLAN device, such as an AP or STA, may include one or more of the following: a processor, memory, radio receiver and / or transmitter (eg, which may be integrated into the transceiver), one or more antennas (For example, the antenna 106 in FIG. 1). The function of the processor may comprise one or more processors. For example, the processor may include one or more of the following: a general purpose processor, a dedicated processor (eg, baseband processor, MAC processor, etc.), a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field Programmable gate array (FPGA) circuits, other types of integrated circuits (ICs), state machines, etc. One or more processors may or may not be integrated with each other. A processor (eg, one or more processors or a subset thereof) may be integrated with one or more other functions (eg, other functions such as memory). The processor performs signal coding, data processing, power control, input / output processing, modulation, demodulation, and / or any other functionality that enables the device to operate in a wireless environment, such as the WLAN of FIG. it can. The processor may be configured such that the processor executes executable code (eg, instructions), including, for example, software and / or firmware instructions. For example, the processor may be configured to execute computer-readable instructions contained in one or more of a processor (eg, a memory and a chipset that includes the processor) or memory. Execution of instructions causes the device to perform one or more of the functions described herein.

  The device can include one or more antennas. The device can use multi-input multi-output (MIMO) technology. One or more antennas can receive a radio signal. The processor can receive a wireless signal via, for example, one or more antennas. One or more antennas can transmit wireless signals (eg, based on signals sent from the processor).

  The device may include one or more devices for storing programming and / or data, such as processor executable code or instructions (eg, software, firmware, etc.), electronic data, databases, or other digital information. It can have a memory. The memory can include one or more memory units. One or more memory units may be integrated with one or more other functions (eg, other functions included in the device, such as a processor). Memory is read only memory (ROM) (eg, EEPROM (erasable programmable read only memory), EEPROM (electrically erasable programmable read only memory), etc.), random access memory (RAM), magnetic disk storage medium, optical storage medium, flash Memory devices and / or other non-transitory computer readable media for storing information may be included. The memory can be coupled to the processor. The processor can communicate with one or more entities of the memory, such as directly via a system bus.

  A WLAN in infrastructure basic service set (BSS) mode may have a basic service set (BSS) access point (AP) and one or more base stations (STAs) associated with the AP. An AP can access or interface to a distributed system (DS) or another type of wired / wireless network that can carry traffic in and out of the BSS. Traffic to the STA can originate from outside the BSS, can be reached through the AP, and can be delivered to the STA. Traffic originating from the STA and destined for the outside of the BSS can be sent to the APs distributed to the respective destinations. Traffic between STAs in the BSS is sent through an AP that allows the source STA to send traffic to the AP, and the AP can deliver the traffic to the destination STA. The traffic between STAs in the BSS may be peer to peer traffic. Such peer-to-peer traffic may be sent directly between the source STA and the destination STA using, for example, a direct link setup (DLS) using IEEE 802.11e DLS or IEEE 802.11z tunnel DLS. A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs can communicate directly with each other. This communication mode may be an ad hoc mode.

  By using the IEEE 802.11 infrastructure mode for operation, the AP can transmit beacons on a fixed channel, eg, the primary channel. This channel may be in the 20 MHz band and may be the BSS operating channel. This channel can also be used by a STA establishing a connection with an AP. The channel access in the IEEE 802.11 system may be CSMA / CA (Carrier Sense Multiple Access with Collision Avoidance). In the infrastructure mode of operation, each STA can sense the main channel. If the STA detects that the channel is busy, the STA can back off. One STA can be transmitted at a given time for a given BSS.

  In various countries around the world, dedicated spectrum can be allocated to wireless communication systems, such as WLAN. The allocated spectrum (eg, below 1 GHz) can be limited in size and channel bandwidth. The spectrum can be fragmented. The available channels are not adjusted and combined for transmission over a wider bandwidth. For example, a WLAN system built with the IEEE 802.11 standard can be designed to operate in such a spectrum. Given such spectrum limitations, WLAN systems support lower bandwidth and lower data rates compared to HT and / or VHT WLAN systems (eg, based on IEEE 802.11n and / or 802.11ac standards). Can be made possible.

  Spectral allocation in one or more countries may be limited. For example, in China, the 470-566 and 614-787 MHz bands can allow 1 MHz bandwidth. In addition to 1 MHz bandwidth, 2 MHz with 1 MHz mode may be supported. The 802.11ah physical layer (PHY) can support 1, 2, 4, 8, and 16 MHz bandwidths.

  802.11ahPHY can operate at less than 1 GHz. 802.11ahPHY can be based on 802.11acPHY. 802.11acPHY can be downclocked (eg, to accommodate the narrow bandwidth required by 802.11ah). 802.11acPHY can be downclocked by a factor of ten. Support of 2, 4, 8 and 16 MHz can be achieved with 1/10 downclocking. Support for 1 MHz bandwidth can use PHY with 32 Fast Fourier Transform (FFT) size.

  In 802.11ah, one or more STAs (eg, up to 6000 STAs including devices such as instruments and sensors) may be supported within a basic service set (BSS). A STA may have different supported uplink and downlink traffic requirements. For example, the STA may be configured to upload data to the server (eg, upload periodically), resulting in uplink traffic. The STA may be queried and / or configured by the server. If the server queries and / or configures the STA, the server can expect the queried data to arrive within a set interval. The server, or server application, can expect confirmation of the configuration to be performed (eg, within a certain interval). Such a traffic pattern may be different from the traffic pattern of the conventional WLAN system. In an 802.11ah system, one or more (eg, 2) bits can be used in the PLCP header of the frame. One or more bits can indicate in the packet the type of acknowledgment expected as a response (eg, an early acknowledgment (ACK) indication). An ACK indication (eg, a 2-bit ACK indication) may be signaled in a signal (SIG) field. The ACK indication may be one or more of the following: 00: ACK, 01: block ACK (BA), 10: non-ACK, 11: not ACK, BA or clear to send (CTS) frame.

  Relay functionality (eg, as introduced in IEEE 802.11ah) can allow more efficient power usage. The relay functionality can reduce the transmission power consumed in the STA. The relay functionality can improve the wireless link state of the STA. Bidirectional relay can include one or more (eg, two) hops. One transmission opportunity (TXOP) for relaying (eg, for explicit ACK exchange) may be shared. Shared TXOP can reduce the number of channel contentions. The frame control field may include relay frame bits (eg, for TXOP operations). The Neighbor Discovery Protocol (NDP), ACK, and / or SIG field may include relay frame bits (eg, for TXOP operation).

  The relay node can receive a frame (for example, a valid frame). The relay node can respond to the received frame with an ACK (eg, in a TXOP sharing operation). If the relay node receives a valid frame, one or more of the following can be applied. If the relay node receives a relay frame bit set to 1, the ACK can be implicit in the next hop transmission after the short interframe space (SIFS). The relay node can respond with an ACK after the SIFS with the relay frame bit set to 1, and can continue the next hop data transmission after the SIFS. The relay node can respond with an ACK after SIFS with the relay frame bit set to 0, and the relay node may not use the remaining TXOP.

  The relay node can set the relay frame bit to 1. For example, if a relay node receives more data bits set to 0, the relay node can set the relay frame bits to 1.

  A flow control mechanism in the relay node can be provided. Support can be provided for using probe requests for relay discovery that can include AP-STA link budget information. The STA can initiate the discovery process. The STA can select a relay node based on the received one or more probe responses. The relay entity may include a relay STA (R-STA), a relay AP (R-AP), and so on. The R-STA may be a non-AP-STA. The R-STA may be a base station that functions as an AP. R-STA, for example, has four address support (eg, capable of sending and / or receiving {To DS = 1, From DS = 1} frames to and / or from the root AP with which it is associated) May have one or more capabilities, including support for receiving and / or forwarding frames from the R-AP, and so on.

  The R-AP may be an AP. The R-AP may, for example, support 4 addresses, support for forwarding frames to the R-STA or receiving from the R-STA, and (e.g., setting a bit or service set identifier of the root AP address and / or beacon You can have one or more capabilities, including the ability to indicate R-AP (by displaying (SSID)). One or more of the following is applicable to R-AP, for example with respect to 4-address support. The R-AP sends and / or receives {To DS = 1, From DS = 1} frames to the associated STA (eg, based on the capabilities of the associated STA) and / or from the associated STA. it can. The R-AP can forward the frame to the associated STA with 3 addresses.

  FIG. 2 is an example of an IEEE 802.11ah relay architecture. The relay AP may include the SSID and / or probe response frame of the root AP's beacon. An A-MSDU (aggregated MAC service data unit) format can be used between the root AP and the relay AP (for example, for frame distribution). Messages that update the forward table (eg, reachable address messages) can be used.

  FIG. 3 shows an example of downlink relay from an AP (eg source) to a STA (eg destination) via a relay node. An explicit ACK can be used. The source AP can send a downlink data frame using the early ACK indication bit. The early ACK indication bit of the downlink data frame may be set to 00. The relay node can send an ACK back to the source AP using the early ACK indication bit set to 11 for the next outgoing frame. The relay node can send data using a different MCS at SIFS time, and the early ACK indication bit can be set to 00. The relay node can buffer frames (eg, data frames). The frame may be buffered until the frame is delivered (eg, delivered successfully) or a predetermined number of retries (eg, retry limit) is reached. The destination STA can send an ACK using the early ACK indication bit set to 10 at SIFS time. When the source AP receives an ACK from the relay node, the source AP can remove the data frame from its buffer and postpone MAX_PPDU + ACK + 2 * SIFS until the next event.

  FIG. 4 shows an example of uplink relay from a STA (for example, a source) to an AP via a relay node (for example, a destination). An explicit ACK can be used. As shown in FIG. 4, the STA can send an uplink data frame to the relay node using an early ACK indication bit. The early ACK indication bit may be set to 00. The relay node can send an ACK and set the early ACK indication bit to 11 for the next outgoing frame. The relay node can send a data frame with a different MCS and set the early ACK indication bit to 00 at SIFS time. The relay node can buffer frames (eg, data frames). The frame may be buffered until the frame is delivered (eg, delivered successfully) or a predetermined number of retries (eg, retry limit) is reached. The destination AP can send an ACK using the early ACK indication bit set to 10 at SIFS time. Upon receiving an ACK frame from the relay node, the STA can remove the data frame from its buffer and postpone MAX_PPDU + ACK + 2 * SIFS until the next event (eg, after receiving an ACK from the destination AP).

  FIG. 5 shows an example of relay operation using implicit ACK. As shown in FIG. 5, the source node can send a downlink data frame using a response frame bit set to 11. A response frame bit set to 11 may indicate that another data frame may follow the STA. Within the SIFS time, the source node can receive the PHY SIG field with the response frame bit set to 00. The source node can check the PAID subfield in the PHY SIG field. The relay node can send data frames using different MCSs. The relay node can set the response frame bit to 00 and set its PAID subfield to the STA's PAID subfield. The destination node can send an ACK using the response frame bit set to 10.

  In IEEE 802.11ah, a short beacon frame format can be supported. A short beacon frame control type and / or subtype indication may be provided. FIG. 6 shows an example of a short beacon frame format. A short beacon may include one or more of the following fields: compressed SSID, timestamp, modification sequence, time of next full beacon, access network option, and / or 3 included in the FC field. Bit BW field. The compressed SSID field can be calculated as a cyclic redundancy check (CRC) of the SSID. The CRC may be calculated using the same function that can be used to calculate the FCS of the MPDU. The timestamp field is 4 bytes long. The timestamp field can contain the 4 least significant bits (LSB) of the AP timestamp. The change sequence field is 1 byte long. The change sequence field may be incremented each time important network information changes. The next full beacon time field may indicate the time of the next full beacon frame. The time field of the next all beacons may be displayed as the 3 most significant bytes of the 4 LSBs of the AP timestamp in the next all beacon frame. If the AP periodically transmits all (eg, long) beacon frames, the next all beacon time field is present in the short beacon frame. The beacon frame can include an access network option field in the short beacon frame.

  In IEEE 802.11, carrier-oriented WiFi can provide one or more of the following: fairness between BSS center and BSS edge users, improved BSS edge performance, OBSS interference coordination, higher spectral efficiency and utilization Or cellular off-road.

  IEEE 802.11 high-efficiency WLAN (HEW) systems provide real-world data throughput achieved by IEEE 802.11 users in high-density networks with a large number of users and devices (eg, Wi-Fi hotspots, office buildings, etc.). Can provide an increase. Systems and methods for enhancing 802.11 PHY and MAC with 2.4 and 5 GHz performance may also be provided. Performance enhancements can provide one or more of the following: improved spectral efficiency and area throughput, improved real-world performance in indoor and outdoor deployments (eg, interference sources, presence of dense heterogeneous networks, heavy users) Adjustment of loaded AP).

  One or more metrics may be considered by the STA when selecting an AP for association (eg, in a non-relay based WiFi network). The metrics can include received signal strength, path loss, or link quality of an AP (eg, an AP that can transmit beacon frames or probe response frames).

  The relay node, and associated functionality, can be used to serve STAs (eg, STAs that may suffer a low link budget when communicating directly with an AP). IEEE 802.11ah can provide relay nodes and / or relay-type STAs (eg, to address the potential for low link budget problems in the case of STA macro-type coverage). The relay node can also be used in other WLAN variants.

  When a relay node is used, the received signal strength, path loss, or link quality of a relay node (eg, R-AP, R-STA, etc.) that transmits a beacon frame or a probe response frame is Insufficient information (eg, from the source node to the destination node) cannot be provided. FIG. 7 shows an example of relay path selection by the STA. The STA can receive a beacon frame or a probe response frame from a relay node (eg, via path V1). The link quality between the STA and the relay node is better than the link quality between the STA and the root AP (for example, via the route U1). The path loss between the relay node (for example, via the path V2) and the root AP is larger than the path loss between the STA and the root AP. Selecting a relay node based on received beacon and / or probe response frame quality can result in a relay path that may exhibit worse path loss and / or link quality than a direct path.

FIG. 8 shows an example of selecting a relay path of a route AP connected to two or more (for example, two) relay nodes. The source node (for example, STA) is sent from the relay node 2 (
For example, transmissions (eg, via beacon frames, short beacon frames, or probe response frames) can be received (via path V3). The link quality between the STA and the relay node 2 is better than the link quality between the STA and the relay node 1 (for example, via the route U1). The path loss between the AP and the relay node 2 is larger than the path loss between the AP and the relay node 1. Selecting a relay node based on the link quality of the received transmission can result in a relay path via relay node 2 that can exhibit worse path loss and / or link quality than the relay path via relay node 1. An efficient AP discovery mechanism can allow STAs to find a relay that can include consideration of total link quality.

  In a relay-based WLAN architecture, the relay node can receive data frames from the source node and can respond to the source node with an ACK. The relay node can send the data frame to the destination node. When the destination node receives a data frame from the relay node, the destination node can respond to the relay node with an ACK. The path between the relay node and the destination node is not reliable (eg, there may be a temporary outage). When the link between the relay node and the destination node experiences an adverse condition, data frames from the source node may be buffered at the relay node. Buffered data frames can cause buffer management problems (eg, buffer overflow). The source node does not know the link quality of the relay path between the relay node and the destination node. The source node will continue to send data to the relay node, and congestion at the relay node may increase. A flow control mechanism (eg, an efficient flow control mechanism) at the relay node can avoid a lack of path reliability.

  When a relay node is used, channel access contention can be reduced by the relay node sharing one transmission opportunity (TXOP). Such TXOP sharing may be provided in IEEE 802.11ah. By sharing the TXOP, the source node (eg, the initiator of the TXOP reservation) can reserve the TXOP at a certain time interval. The reserved TXOP can take into account the worst case of the link between the relay node and the destination node. The reserved TXOP may be longer (eg, much longer) than the actual time period of transmission from the source node to the relay node and from the relay node to the destination node. A relay-shared TXOP may be truncated (eg, efficiently truncated) when the actual transmission at the relay node ends early.

  An information element (IE) or field indicating the link quality between the relay node and the root AP is sent by the relay node, such as an R-AP (for example, to cause the terminating STA to determine the total link quality of the relay path). Can be transmitted by transmission. The transmission may be a beacon frame, a short beacon frame, or a probe response frame. The compressed SSID of the root AP can be used for its transmission.

  FIG. 9 shows an exemplary frame format for transmission where one bit in the frame control field for transmission can indicate that the transmitter is a relay node (eg, instead of the root AP). The transmission may be a short beacon frame. The transmission indicating that the transmitter is a relay node may be a beacon frame or a probe response frame (e.g., a short beacon frame or a probe response frame has a field similar to that described in the short beacon frame example. Can be included). If the frame control field is set to a value of 1, the transmitter becomes a relay node. If the frame control field is set to a value of 0, the transmitter becomes a non-relay node. As shown in FIG. 9, a bit in the transmission frame control field may indicate the presence of a link quality field between the transmission relay and the root AP. A frame control field bit set to a value of 1 means that the field exists, and a value of 0 means that the field is absent. Bits reserved in the frame control field can be used to indicate the presence of a link quality field between the relay and the root AP. The link quality presence field or relay indicator field may be signaled implicitly (eg, by methods such as CRC masking, scrambler start seed value, relative phase change of SIG field, or pilot value or pattern of PLCP header). A link quality presence bit or relay indication bit in the frame control field may indicate that the link quality between the relay and the root AP is included in the transmission. One or more octets may be used for the link quality field between the relay and the root AP. The link quality field between the relay and the root AP can represent 64 to 4096 levels of link quality in dB. The link quality field between the relay and the root AP can indicate the link quality (eg, path loss, packet error / loss rate, transmission latency, etc.) between the relay node and the root AP. The link quality (eg, incremental link quality) estimate is incremented until indicated as the overall link quality from the AP to the STA.

  FIG. 10 illustrates an example of transmission in which the link quality between a relay node and a root AP can be signaled (eg, can be explicitly signaled) by an IE (eg, link quality IE between the relay and root AP). Shows a typical frame format. The transmission may be a short beacon frame. The transmission signaling the link quality between the relay node and the root AP may be a beacon frame or a probe response frame (eg, a short beacon frame or a probe response frame is similar to that described in the short beacon frame example Field can be included). The IE may be included in a transmission (eg, beacon frame, short beacon frame, or probe response frame). The link quality presence bit or the explicit or implicit indication of relaying may not be used. The IE may include one or more of the following: an octet element ID subfield, an octet length subfield, or one or more octets that may provide a link subfield between the relay and the root AP. The link quality can represent link quality of multiple levels (for example, levels from 64 to 4096) in dB units.

  A STA immediately after receiving a transmission (eg, a beacon frame, a short beacon frame, or a probe response frame) can check certain fields or IEs in the transmission to determine if the transmitter of the transmission is a relay node. . The STA can check the link quality presence or relay indicator field (eg, if the link quality presence bit is present). If the link quality presence or relay indicator field bit is set to 1, the STA knows that the link quality field between the relay and the root AP is included in the transmission.

A source node (eg, an STA with traffic to transmit) can determine one or more link qualities. For example, the source node may determine which relay to use if multiple relay nodes are available (eg, to determine whether to use a relay node instead of direct transmission to the destination node) Therefore, the quality of each link on the relay path can be determined. The determination of one or more link qualities, such as determining the total link quality associated with the combined link from the STA to the relay node and from the relay node to the root AP, can include one or more of the following: . The STA can check whether the link quality IE between the relay and the root AP is included in the transmission (eg, the STA can perform this check whether or not it checks the link quality presence or relay indicator field). ). If a link quality IE between the relay and the root AP is included in the transmission, its inclusion indicates that the transmitter of the transmission is a relay node. The STA can receive a transmission (eg, a beacon frame, a short beacon frame, or a probe response frame) that can indicate the link quality between the relay node and the root AP, for example, denoted Q _AP-Relay . The received transmission field or IE may indicate the link quality. The STA can determine (eg, estimate) the link quality between the relay node and itself. The STA can determine the link quality based on the received transmission transmitted from the relay node, for example, expressed as _QSTA-Relay . The STA is the total link quality of the indirect route (for example, the STA relayed to the root AP), for example,
(Equation 1)
Q _{Relay path} = Q _STA-Relay + Q _AP-Relay
Q _{Relay path} can be determined (for example, calculated). An indirect path can be a linked link. A STA (eg, a scanning STA) can consider the relay node as a candidate (eg, association) if the total link quality Q _{Relay path} meets the requirements. The STA can select an entity to transmit based on the total link quality (eg, to a relay node or root AP). The entity selected has a total link quality that meets the requirements (eg, the total link quality of the combined links is better than the quality associated with the direct path to the root AP and / or is associated with another relay node. If the total link quality is better than the threshold requirement, it is a relay node.

  Methods, systems, and means are described for describing relay flow control of relay functionality that can be applicable to 802.11ah and other 802.11 systems (eg, HEW). An action frame (eg, a flow control notification frame) may be defined. The relay node can perform flow control on a link between the source node and the relay node. The relay node can perform flow control when the link between the relay node and the destination node deteriorates. Data frames from the source node can be buffered at the relay node and can lead to congestion and / or buffer overflow (eg, more buffering may be required as the link degrades) . The relay node can notify the source node about flow control. The relay node can notify the flow control by sending a flow control notification frame to the source node. The flow control notification frame may be sent as a unicast frame in uplink and downlink operations. The flow control notification frame may be sent out as a broadcast frame in the downlink. The flow control node address may be signaled by a flow control notification frame. The flow control notification frame may signal the address of the relay node on the relay link (for example, between the destination node and the relay node). Relay nodes, signaled in the flow control notification frame, may experience adverse link quality.

  The flow control notification frame may signal the destination node address. The data traffic of the terminating STA (eg, terminating STA belonging to a trunk that is experiencing a link problem) can be affected.

  The flow control notification frame may be transmitted as a unicast or broadcast frame. The transmitter address (TA) field in the MAC header of the frame may be set to the relay node address. The flow control information of the flow control notification frame can refer to the relay node specified by the TA address. FIG. 11 shows an exemplary frame format of the flow control notification frame. The category field may be set to a value that represents a two-hop relay (eg, as may be specified in the standard). The action (eg, 2 hop relay action) field may be set to a value (eg, a unique value) that can represent a flow control notification. The action field can be set as specified in the standard.

  FIG. 12 shows an example of a flow control notification element. As shown in FIG. 12, the element ID field may be set to a value (eg, a unique value) that can represent a flow control notification element. The element ID field can be set as specified in the standard. The length field can indicate the number of octets in the information field (eg, the field following the element ID and length field). The flow control duration field for each access category (AC) (eg, background (BK), best effort (BE), video (VI), and voice (VO)) is the flow control applied at the corresponding AC relay node. Can be shown. The time unit of the flow control period is Mμs. The flow control data rate field for each AC (eg, BK, BE, VI, and VO) indicates the data rate (eg, maximum data rate) that the terminating STA can transmit to the relay node during the corresponding AC flow control period. be able to.

  The TA address of the MAC header can indicate (eg, identify) a relay node to which the received flow control information is applied. With a two-hop relay architecture (eg, a relay node can be associated with one root AP), the TA address in the MAC header identifies a relay link that may experience congestion or adverse link quality in the uplink case. Can provide enough information. Identifying the relay link using the TA address in the MAC header can reduce signaling overhead. In the downlink where several terminating STAs can be associated with one relay node, the TA address in the MAC header is the relay link between the terminating STA and a relay node that may experience congestion and / or adverse link quality. Cannot be specified (for example, uniquely specified). The flow control notification frame may signal the address of the relay node of the relay link that may experience adverse link quality (eg, in uplink operation). The flow control notification frame may signal the destination node address (eg, in downlink operation). The flow control notification element may be piggybacked on a data frame or control frame from the relay node to the source node.

  For example, a flow control notification element as shown in FIG. 13 may be used. A flow control notification element as shown in FIG. 13 can specify the flow control period and data rate limits for the combined access categories (instead of providing one for each AC).

  FIG. 14 shows an exemplary frame format for a flow control notification frame in which the destination node address may be signaled in the flow control notification frame. As shown in FIG. 14, the category field may be set to a value that can represent a two-hop relay (eg, as may be specified in the standard). The action (eg, 2 hop relay action) field may be set to a value (eg, as may be specified in the standard) that represents a flow control notification.

  FIG. 15 shows an exemplary design of a flow control notification element. As shown in FIG. 15, the element ID field may be set to a value that can represent a flow control notification element (eg, as may be specified in the standard). The length field can indicate the number of octets in the information field (eg, the field following the element ID and length field). The destination node address (eg, end STA address) may be set to the destination node (eg, end STA) of the 6-byte MAC address. The flow control notification frame can indicate that the received flow control information can be applied to the relay node specified by the TA address of the MAC header. The flow control period field of each access category (AC) (eg, BK, BE, VI, and VO) may indicate the period of flow control applied at the corresponding AC relay node. The time unit of the flow control period is Mμs. The flow control data rate field for each AC (eg, BK, BE, VI, and VO) indicates the data rate (eg, maximum data rate) that the terminating STA can transmit to the relay node during the corresponding AC flow control period. be able to.

  The flow control can include one or more of the following. The relay node can monitor the buffer occupation amount in the relay node. The relay node can monitor the link quality between the relay node and the destination node. The relay node can determine that flow control (eg, to mitigate the identified congestion) must be applied. The relay node can send a flow control notification frame to the source node. The flow control notification frame can include, for example, a flow control parameter as described herein. The source node can specify the address of a node to which flow control can be applied (eg, immediately after receiving a flow control notification frame). The address may be a relay address (eg, in uplink operation). The address may be a relay address (eg, in downlink operation) or a terminal STA address. The source node can acquire information on the flow control notification element. The source node can take action according to the information in the flow control notification element. When the AC flow control period field is received, the source node transmits a corresponding AC data frame targeting the destination address (eg, via the relay node during the period value of the received flow control notification element). ) Can stop. The terminal STA can transmit the data frame directly to the root AP without passing through the relay node (for example, if the link quality between the terminal STA and the root AP is acceptable). The source node can limit the data rate of an AC (e.g., the corresponding AC) targeted to the destination address (e.g., via the relay node for the duration value of the received flow control notification element). The source node may limit the data rate once the AC flow control duration field and the flow control data rate are received. The flow control restriction may end at the source node (eg, after expiration of the flow control period). The source node can resume data frame transmission (for example, normal transmission) to the destination node, for example, via the relay node.

  The data frame may include an indication of contention free termination (CF-end) (eg, to allow a relay node to truncate a TXOP that is not used). One or more of the following can be applied. Bits reserved in the SIGA field (eg, 1 bit) can be used to indicate CF-end (eg, can be reused). The recipient of the data frame can reset the network allocation vector (NAV) at the end of the period indicated in the MAC header. The data frame may also indicate one or more of the following: SIFS time, ACK-time, or short-ACK_time. Bits reserved in the frame control field of the MAC header may be used to indicate CF-end (eg, may be reused). The recipient of the data frame can reset the NAV at the end of the period indicated in the MAC header. The data frame may also indicate one or more of the following: SIFS time, ACK-time, or short-ACK_time. The CF-end indication can be signaled (eg, can be signaled implicitly). The CF-end indication may be signaled using one or more of the following: CRC masking, scrambler start seed value, relative phase change in the SIG field, or pilot value or pattern in the PLCP header.

  In the case of TXOP, a two-hop request-to-send / clear-to-send (RTS / CTS) can establish a TXOP during a relay frame exchange period (eg, the entire period) between a source node, a relay node, and a destination node and / or Or you can make a reservation. It is assumed that the period during which the data frame is transmitted from the relay node to the destination node is the worst case. A period for transmitting a data frame from the relay node to the destination node may be calculated (eg, calculated conservatively). The source node can begin data transmission after SIFS time (eg, after receiving a CTS frame from a relay node).

  The relay node can process the data frame received from the source node. The relay node can send an ACK frame (for example, if the received data frame is correctly decoded and an explicit ACK is used). The STA cannot send an ACK frame (eg, if implicit ACK is used). The source node cannot receive an ACK in SIFS time + ACK_Time time after sending the data frame (for example, if explicit ACK is used and the received data frame is not decoded correctly). The source node cannot receive an implicit ACK (eg, if an implicit ACK is used and the received data frame is not decoded correctly). A data frame with an ACK indication field set to 00 from the relay node can indicate an implicit ACK. The source node can release the TXOP by sending out a CF-end frame. The source node can retransmit the data frame. When the relay node and / or the destination node receives the CF-End from the source node, the relay node and / or the destination node can transmit a CF-end frame.

  The relay node can send the data frame to the destination node. The relay node can set the CF-end indication of the data frame to 1 or a positive number, and (for example, when the duration of adding SIFS time and ACK_Time or Short-ACK_Time to the data frame is shorter than the remaining duration of TXOP) ) The period field of its MAC header can be set. The duration field of the MAC header can be determined (eg, calculated) using the length or data rate of the data frame used for transmission.

  The destination node can process the data frame received from the relay node. The destination node can send an ACK frame to the relay node (eg, if the received data frame is correctly decoded). The destination node can check the CF-end display of the received data frame. The destination node can release the TXOP and reset the NAV of the STA near the destination node (eg, if the CF-end indication is positive). The destination node can send a CF-end frame. The destination node can set the ACK display field of the outgoing ACK frame (eg, to 10). The destination node cannot transmit the CF-end frame when the ACK display field of the departing ACK frame is set to “10”.

  The source node may receive a positive CF-end from the relay node after the SIFS time plus the time to cover the frame sent by the destination node (eg, the required time) (eg, before the current TXOP expires). A CF-end frame can be sent out (just after receiving a data frame with an indication). The frame transmitted by the destination node is an ACK frame or a frame obtained by adding a CF-end frame to the ACK frame. The source node can send a CF-end frame after the period signaled in the received data frame.

  16 and 17 show an exemplary TXOP operation. FIG. 16 shows an example of a TXOP operation using explicit ACK. FIG. 17 shows an example of a TXOP operation using implicit ACK. As shown in FIG. 16, the relay node can send an ACK (eg, an explicit ACK) to the source node (eg, after receiving a data frame from the source node). The relay node can send ACK to the source node before relaying the data frame to the destination node using the CF-end bit. As shown in FIG. 17, the relay node can send the data frame to the destination node using the CF-end bit (eg, after receiving the data frame from the source node). The relay node can send a data frame to the source node without sending an ACK.

  Although features and elements are described above in certain combinations, those skilled in the art will recognize that each feature or element may be used alone or in any combination with other features and elements. In addition to the 802.11 protocol described herein, the features and elements described herein may be applicable to other wireless systems. Further, the methods described herein may be implemented in a computer program, software, or firmware that is incorporated into a computer readable medium for execution by a computer or processor. Examples of computer readable media include electronic signals (transmitted over a wired or wireless connection) and computer readable storage media. Examples of computer readable storage media include, but are not limited to, read only memory (ROM), random access memory (RAM), registers, cache memory, semiconductor memory devices, internal hard disks and removable disks, magnetic media, optical Includes optical media such as magnetic media, CD-ROM discs, and digital versatile discs (DVDs). A processor associated with the software may be used to implement a radio frequency transceiver, WTRU, terminal, base station, RNC, or any host computer for use with the WTRU.

Claims (20)

A method for determining link quality,
Receiving a transmission indicating that the transmitting entity is a relay node, the transmission indicating a first link quality associated with a link between the relay node and a root access point (AP) , Steps and
Determining a second link quality associated with a link between a station (STA) and the relay node;
Determining a total link quality associated with a combined link from the STA to the relay node, the root AP;
Selecting an entity to associate based on the total link quality.   The method of claim 1, wherein the transmission is a beacon frame, a short beacon frame, or a probe response frame.   The method of claim 2, wherein determining the second link quality is estimated by the STA based on the received transmission.   The method of claim 1, further comprising determining the first link quality.   The method of claim 4, wherein the total link quality is associated with a combination of the first link quality and the second link quality.   The method of claim 1, further comprising determining whether the total link quality meets a requirement.   The method of claim 6, wherein if the total link quality meets the requirement, the selected entity is the relay node.   The method of claim 1, wherein the indication that the transmitting entity is the relay node is explicitly signaled in an information element.   The method of claim 1, wherein the indication that the transmitting entity is the relay node is indicated by the presence of the first link quality in the frame of transmission.   The method of claim 1, further comprising: sending data to the relay node and an indication that the data is to be relayed to the AP. Station (STA),
Receiving a transmission indicating that the transmitting entity is a relay node, the transmission indicating a first link quality associated with a link between the relay node and a root access point (AP);
Determining a second link quality associated with a link between a station (STA) and the relay node;
Determining the total link quality associated with the combined link from the STA to the relay node, the root AP;
A STA comprising a processor configured to select an entity to associate based on the total link quality.   The STA according to claim 11, wherein the transmission is a beacon frame, a short beacon frame, or a probe response frame.   The STA of claim 12, wherein the processor is further configured to estimate the second link quality based on the received transmission.   The STA of claim 11, wherein the processor is further configured to determine the first link quality.   The STA of claim 14, wherein the total link quality is associated with a combination of the first link quality and the second link quality.   The STA of claim 11, wherein the processor is further configured to determine whether the total link quality meets a requirement.   The STA according to claim 16, wherein the selected entity is the relay node when the total link quality satisfies the requirement.   The STA according to claim 11, wherein the transmission indicating that the transmitting entity is the relay node is explicitly signaled in an information element.   The STA according to claim 11, wherein the transmission indicating that the transmitting entity is the relay node includes the presence of the first link quality in a frame of the transmission.
The STA of claim 11, wherein the processor is further configured to send data to the relay node and an indication that the data will be relayed to the AP.