TW201513716A - Discovery, transmit opportunity (TXOP) operation and flow control for range extension in WiFi - Google Patents

Abstract

Systems, methods, and instrumentalities are disclosed for a station to determine a link quality. A station (STA) may determine the quality of a path that includes a relay node by determining a link quality associated with each link in the path. The STA may receive a transmission indicating that a transmitting entity is a relay node. The transmission may indicate a first link quality associated with a link between the relay node and a root access point (AP). The STA may determine a second link quality associated with a link between the (STA) and the relay node, e.g., the STA may estimate the second link quality. The STA may determine a total link quality associated with a combined link from the STA to the relay node to the root AP. The STA may select an entity to associate with based on the total link quality.

Description

WiFi range extension discovery, transmission opportunity (TXOP) operation and flow control

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of the benefit of the benefit of the benefit of the benefit of the benefit of the benefit of the benefit of the benefit of the benefit of the disclosure.

Multi-point hop WiFi systems can be used to improve coverage and capacity on a single access point (AP) system. The multi-hop hop WiFi system may use a relay AP and/or a relay type website station (STA) to improve the channel condition of the STA, which may otherwise suffer from bad channel conditions or coverage. In a relay-based WiFi system, an STA that receives a management frame (eg, a beacon frame, a probe response frame, etc.) from a relay AP may not have sufficient information for the entire relay path. For example, the STA may not have information about the link between the root AP and the relay AP. The root AP may not have information about, for example, a link between the relay AP and the destination STA.

The Summary of the Invention provides an introduction to the selection of concepts in a simplified form, which are further described in the following detailed description. The summary is not intended to identify key features or essential features of the claimed subject matter, and is not intended to limit the scope of the claimed subject matter.
Systems, methods and tools for determining the quality of a link for a station are disclosed. For example, a station (STA) can determine the quality of a path including a relay node by determining the link quality associated with each link in the path. The STA may receive a transmission indicating that the transport entity is a relay node. The transmission can be a beacon frame, a short message frame or a probe response frame. A relay device (e.g., a WTRU) may be a dedicated relay or other device (e.g., a station that acts as a relay, an access point (AP) that is a relay, or a non-station, such as a station that acts as an AP, the AP acts as relay). 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 a destination node associated with the material to be transmitted by the STA. The STA may determine a second link quality associated with the link between the STA and the relay node, for example, the STA may estimate the second link quality by measuring the transmitted metric. The STA may determine the overall link quality associated with the link from the STA to the relay node to the root AP.
The STA may select an entity to associate based on the overall link quality. The STA can use the overall link quality to determine whether to send data to the root AP via the relay or directly to the root AP. For example, the STA may determine whether the overall link quality meets the requirements (eg, whether the overall link quality is better than the quality of the link between the STA and the root AP, and whether the overall link quality is above a critical value such as the SNR threshold) ). The STA may select the associated relay node to transmit to the root AP when the overall link quality meets the demand.
The indication that the transport entity is a relay node can be explicit or implicit. An exemplary explicit indication that the transmitting 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 transmitted frame.

100‧‧‧Communication system
102, 102a, 102b, 102c, 102d‧‧‧ wireless transmit/receive unit (WTRU)/access point (AP)
103, 104, 105‧‧‧ Radio Access Network (RAN)
106, 107, 109‧‧‧ core network/antenna
108‧‧‧Public Switched Telephone Network (PSTN)
110‧‧‧Internet/Station (STA)
112‧‧‧Other networks/STAs
114‧‧‧Network
114a, 114b‧‧‧ base station
115, 116, 117‧‧‧ Air Intermediary/Distribution System (DS)
118‧‧‧Processor/Server
120‧‧‧ transceiver
122‧‧‧transmit/receive components/basic service set (BSS)
124‧‧‧Speaker/Microphone
126‧‧‧Digital keyboard
128‧‧‧Display/Touchpad
130‧‧‧Cannot remove memory
132‧‧‧Removable memory
134‧‧‧Power supply
136‧‧‧Global Positioning System (GPS) chipset
138‧‧‧Other peripheral equipment
ACK‧‧‧early response
CF‧‧‧No contention
CRC‧‧‧cyclic redundancy check
CTC‧‧‧Clear Send
IE‧‧‧Information elements
NAV‧‧‧Network Assignment Vector
PHY‧‧‧ physical layer
R-AP‧‧‧Relay AP
R-STA‧‧‧ Relay STA
RTS‧‧‧ request to send
SIFS‧‧‧ Short inter-frame space
SIG‧‧‧ signal
SSID‧‧‧Service Set Identifier
TXOP‧‧‧ transmission opportunity

A more detailed understanding can be obtained from the description given below by way of example with reference to the accompanying drawings, in which:
Figure 1A depicts an exemplary communication system.
FIG. 1B depicts an exemplary wireless transmit/receive unit (WTRU).
Figure 1C depicts an exemplary wireless local area network (WLAN) device.
Figure 2 depicts an example of a relay architecture in IEEE 802.11ah.
Figure 3 depicts an example of a downlink relay (e.g., from an AP to a STA) that utilizes an explicit ACK.
Figure 4 depicts an example of an uplink relay (e.g., from STA to AP) utilizing an explicit ACK.
Figure 5 depicts an example of a relay operation using an implicit ACK.
Figure 6 depicts an example of transmission.
Figure 7 depicts an example of relay path selection in the case of a relay node and a source node.
Figure 8 depicts an example of relay path selection in the case of one or more relay nodes and source nodes.
Figure 9 depicts an example of a frame format for transmission, where the frame control field bit may indicate whether there is a link quality between the relay and the root AP.
Figure 10 depicts an example of a frame format for transmission where the link quality between the relay and the root AP can be provided by an information element (IE).
Figure 11 depicts an example of a frame format for a flow control notification frame that can signal the address of a relay node.
Figure 12 depicts an example of a frame format for the flow control notification element format of the exemplary flow control element shown in Figure 11.
Figure 13 depicts an example of a simplified flow control notification element format.
Figure 14 depicts an example of a frame format for a flow control notification frame that can signal the address of a destination node.
Figure 15 depicts an example of a frame format of the flow control notification element format of the exemplary flow control element shown in Figure 14.
Figure 16 depicts an example of a Transport Opportunity (TXOP) operation utilizing explicit ACK.
Figure 17 depicts an example of a TXOP operation that utilizes an implicit ACK.

Example embodiments are described in detail below with reference to the various drawings. While the present invention has been described with respect to the specific embodiments of the present invention, it is understood that the details are not intended to limit the scope of the invention. Moreover, the figures may illustrate one or more message patterns that are used in the examples. Other embodiments may be used. The order of the messages can be changed after the appropriate ones. Messages can be omitted when not needed, and additional messages can be added.
FIG. 1A is a diagram of an example communication system 100 in which one or more of the disclosed features may be implemented. For example, a wireless network (eg, a wireless network including one or more components of communication system 100) can be configured to extend beyond the wireless network (eg, extending beyond a firewall associated with the wireless network) The bearer can be assigned QoS characteristics.
Communication system 100 may be a multiple access system that provides content such as voice, material, video, messaging, broadcast, etc. to multiple wireless users. Communication system 100 can enable multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, communication system 100 can use 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.
As shown in FIG. 1A, communication system 100 can include at least one wireless transmit/receive unit (WTRU), such as multiple WTRUs, such as WTRUs 102a, 102b, 102c, and 102d, Radio Access Network (RAN) 103/104/ 105, core network 106/107/109, public switched telephone network (PSTN) 108, internet 110, and other networks 112, but it will be understood that the disclosed embodiments encompass any number of WTRUs, base stations , network, and/or network components. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and/or communicate in wireless communication. 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), mobile stations, fixed or mobile subscriber units, pagers, mobile phones, personal digital assistants (PDA), smart phones, portable computers, netbooks, personal computers, wireless sensors, consumer electronics, and more.
Communication system 100 can also include a base station 114a and a base station 114b. Each of the base stations 114a, 114b can be configured to have a wireless interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks (eg, core network 106/107) / 109, Internet 110 and/or network 112) any type of device. For example, base stations 114a, 114b may be base station transceiver stations (BTS), node B, eNodeB, home node B, home eNodeB, website controller, access point (AP), wireless router, and the like. Although base stations 114a, 114b are each depicted as a single element, it will be understood that base stations 114a, 114b may include any number of interconnected base stations and/or network elements.
The base station 114a may be part of the RAN 103/104/105, which may also include other base stations such as a website controller (BSC), a radio network controller (RNC), a relay node, and the like. And/or network elements (not shown). Base station 114a and/or base station 114b may be configured to transmit and/or receive wireless signals within a particular geographic area, which may be referred to as cells (not shown). Cells can also be divided into cell sectors. For example, a cell associated with base station 114a can be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., each sector of the cell has a transceiver. In another embodiment, base station 114a may use multiple input multiple output (MIMO) technology, and thus multiple transceivers for each sector of the cell may be used.
The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over the null planes 115/116/117, which may be any suitable wireless communication link ( For example, radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The null intermediaries 115/116/117 can be established using any suitable radio access technology (RAT).
More specifically, as previously discussed, communication system 100 can be a multiple access system and can utilize one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, base station 114a and WTRUs 102a, 102b, 102c in RAN 103/104/105 may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use wideband CDMA ( WCDMA) to establish an empty intermediate plane 115/116/117. WCDMA may include, for example, 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, base station 114a and WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may use Long Term Evolution (LTE) and/or Advanced LTE (LTE-A) to establish an empty intermediate plane 115/116/117.
In other embodiments, base station 114a and WTRUs 102a, 102b, 102c may implement such as IEEE 802.16 (ie, Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Temporary Standard 2000 (IS-2000) Radio technology such as Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rate GSM Evolution (EDGE), GSM EDGE (GERAN).
For example, the base station 114b in FIG. 1A can be a wireless router, a home Node B, a home eNodeB, or an access point, and any suitable RAT can be used for facilitating in, for example, a company, a home, a vehicle, a campus. A local area communication connection. In one embodiment, base station 114b and WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, base station 114b and 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, base station 114b and WTRUs 102c, 102d may use a cellular based RAT (eg, WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish picocells or femtocells ( Femtocell). As shown in FIG. 1A, the base station 114b can have a direct connection to the Internet 110. Therefore, the base station 114b does not have to access the Internet 110 via the core network 106/107/109.
The RAN 103/104/105 can communicate with a core network 106/107/109, which can be configured to provide voice, data, applications, and/or Voice over Internet Protocol (VoIP) services to the WTRU 102a, Any type of network of one or more of 102b, 102c, 102d. For example, the core network 106/107/109 can provide call control, billing services, mobile location based services, prepaid calling, internetworking, video distribution, etc., and/or perform advanced security functions such as user authentication. Although not shown in FIG. 1A, it is to be understood that the RAN 103/104/105 and/or the core network 106/107/109 may communicate directly or indirectly with other RANs, which may be used with the RAN 103/ 104/105 the same RAT or a different RAT. For example, in addition to being connected to the RAN 103/104/105, which may employ E-UTRA radio technology, the core network 106/107/109 may also be in communication with other RANs (not shown) that use GSM radio technology.
The core network 106/107/109 can also be used 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 Plain Old Telephone Service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use public communication protocols such as TCP, users in the Transmission Control Protocol (TCP)/Internet Protocol (IP) Internet Protocol Suite. Packet Protocol (UDP) and IP. Network 112 may include a wireless or wired communication network that is owned and/or operated by other service providers. For example, network 112 may include another core network connected to one or more RANs that may use the same RAT as RAN 103/104/105 or a different RAT.
Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities, i.e., the WTRUs 102a, 102b, 102c, 102d may be configured to communicate with different wireless networks over multiple communication links. Multiple transceivers for communication. For example, the WTRU 102c shown in FIG. 1A can be configured to communicate with a base station 114a that uses a cell-based radio technology and with a base station 114b that uses an IEEE 802 radio technology.
FIG. 1B depicts an exemplary wireless transmit/receive unit, WTRU 102. The WTRU 102 may be utilized in one or more of the communication systems described herein. As shown in FIG. 1B, the WTRU 102 may include a processor 118, a transceiver 120, a transmit/receive element 122, a speaker/microphone 124, a numeric keypad 126, a display/touchpad 128, a non-removable memory 130, and a removable In addition to memory 132, power source 134, global positioning system (GPS) chipset 136, and other peripheral devices 138. It should be understood that the WTRU 102 may include any subset of the above-described elements while remaining consistent with the embodiments.
The processor 118 can 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 associated with the DSP core, a controller, a micro control , dedicated integrated circuit (ASIC), field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), state machine, etc. Processor 118 may perform signal coding, data processing, power control, input/output processing, and/or any other functionality that enables WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to a transceiver 120 that can be coupled to the transmit/receive element 122. Although processor 118 and transceiver 120 are depicted in FIG. 1B as separate components, it should be understood that processor 118 and transceiver 120 can be integrated together into an electronic package or wafer.
Transmit/receive element 122 may be configured to transmit signals to or from a base station (e.g., base station 114a) via null intermediaries 115/116/117. For example, in one embodiment, the transmit/receive element 122 can be an antenna configured to transmit and/or receive RF signals. In another embodiment, the transmit/receive element 122 may be a transmitter/detector configured to transmit and/or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit/receive element 122 can be configured to transmit and receive both RF signals and optical signals. It should be understood that the transmit/receive element 122 can be configured to transmit and/or receive any combination of wireless signals.
Moreover, although the transmit/receive element 122 is depicted as a single element in FIG. 1B, the WTRU 102 may include any number of transmit/receive elements 122. More specifically, the WTRU 102 may use 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 null intermediaries 115/116/117.
The transceiver 120 can be configured to modulate a signal to be transmitted by the transmit/receive element 122 and configured to demodulate a signal received by the transmit/receive element 122. As described above, the WTRU 102 may have multi-mode capabilities. Accordingly, transceiver 120 may include multiple transceivers for enabling WTRU 102 to communicate via multiple RATs, such as UTRA and IEEE 802.11.
The processor 118 of the WTRU 102 may be coupled to a speaker/microphone 124, a numeric keypad 126, and/or a display/touchpad 128 (eg, a liquid crystal display (LCD) unit or an organic light emitting diode (OLED) display unit), And the user input data can be received from the above device. The processor 118 can also output data to the speaker/microphone 124, the numeric keypad 126, and/or the display/touchpad 128. In addition, the processor 118 can access information from any type of suitable memory and store the data in any type of suitable memory, such as non-removable memory 130 and/or removable. Except memory 132. Non-removable memory 130 may include random access memory (RAM), readable memory (ROM), hard disk, or any other type of memory storage device. The removable memory 132 can include a Subscriber Identity Module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In other embodiments, processor 118 may access data from memory that is not physically located on WTRU 102 and located on a server or home computer (not shown), and store data in the memory.
The processor 118 can receive power from the power source 134 and can be configured to distribute power to other components in the WTRU 102 and/or to control power to other elements in the WTRU 102. Power source 134 can be any device suitable for powering WTRU 102. For example, the power source 134 may include one or more dry cells (nickel cadmium (NiCd), nickel zinc (NiZn), nickel hydrogen (NiMH), lithium ion (Li-ion), etc.), solar cells, fuel cells, and the like.
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. The WTRU may receive location information from the base station (e.g., base station 114a, 114b) plus or in place of GPS chipset 136 information through null intermediaries 115/116/117, and/or based on two or more adjacent base stations The timing of the received signal determines its position. It should be understood that the WTRU 102 may obtain location information by any suitable location determination method while remaining consistent with the embodiments.
The processor 118 can also be coupled to other peripheral devices 138, which can include one or more software and/or hardware modules that provide additional features, functionality, and/or wireless or wired connections. For example, peripheral device 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photo or video), a universal serial bus (USB) port, a vibrating device, a television transceiver, and a hands-free Headphones, blue buds Modules, FM radio units, digital music players, media players, video game player modules, Internet browsers, and more.
Figure 1C shows an exemplary wireless local area network (WLAN) device. One or more of the devices can be used to implement one or more of the features described herein. The WLAN may include, but is not limited to, an access point (AP) 102, a station (STA) 110, and an STA 112. STAs 110 and 112 can be associated with AP 102. The WLAN may be configured to implement one or more of the IEEE 802.11 communication standards, which may include channel access schemes such as DSSS, OFDM, OFDMA, and the like. The WLAN can operate in a mode such as an infrastructure mode or an ad-hoc mode.
A WLAN operating in an infrastructure mode may include one or more APs in communication with one or more associated STAs. The AP and the STA associated with the AP may include a Basic Service Set (BSS). For example, AP 102, STA 110, and STA 112 may include BSS 122. An extended service set (ESS) may include one or more APs (with one or more BSSs) and STAs associated with the APs. The AP may have access and/or interfaces to a distribution system (DS) 116 that may be wired and/or wirelessly connected and may carry traffic to the AP and/or carry information from the AP. Business. Traffic originating from STAs in the WLAN outside the WLAN may be received by an AP in the WLAN, which may send traffic to STAs in the WLAN. Traffic originating from STAs in the WLAN to outside the WLAN (eg, to the server 118) may be sent to an AP in the WLAN, which may send traffic to the destination, such as via the DS 116 to the network 114 to be sent To the server 118. The traffic between STAs in the WLAN can be sent through one or more APs. For example, a source STA (e.g., STA 110) may have traffic for a destination STA (e.g., STA 112). The STA 110 can send traffic to the AP 102, and the AP 102 can send traffic to the STA 112.
The WLAN can operate in ad-hoc mode. The ad-hoc mode WLAN may be referred to as an Independent Basic Service Set (IBBS). In an ad-hoc mode WLAN, STAs can communicate directly with each other (e.g., STA 110 can communicate with STA 112 without requiring such communication to be routed through the AP).
An IEEE 802.11 device (eg, an IEEE 802.11 AP in a BSS) can use a beacon frame to inform the presence of a WLAN network. An AP, such as AP 102, can transmit beacons on a channel such as a fixed channel, such as a primary channel. The STA can establish a connection with the AP using a channel such as a primary channel.
The STA and/or AP may use a Carrier Sense Multiple Access (CSMA/CA) channel access mechanism with collision avoidance. In CSMA/CA, STAs and/or APs can listen to the primary channel. For example, if the STA has data to send, the STA can listen to the main channel. If the primary channel is detected to be busy, the STA can back off. For example, a portion of a WLAN or WLAN may be configured such that one STA may transmit at a given time (eg, at a given BSS). Channel access may include RTS and/or CTS signaling. For example, the exchange of request to send (RTS) frames can be transmitted by the transmitting device, and the clear to send (CTS) frame can be transmitted by the receiving device. 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 may respond with a CTS frame. The CTS frame may include a time value that may alert other STAs to defer access to the media and the AP that initiated the RTS may transmit the data of the RTS. When receiving a CTS frame from the STA, the AP can send data to the STA.
The device can preserve the spectrum of the Network Allocation Vector (NAV) field. For example, in the 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 to the time when the channel is expected to be used. When the STA sets the NAV, the NAV can be set for the associated WLAN or a subset thereof (eg, BSS). Other STAs can count down NAV to zero. When the counter reaches zero, the NAV function can indicate to other STAs that the channel is now available.
A device in a WLAN, such as an AP or STA, may include one or more of: a processor, a memory, a radio receiver, and/or a transmitter (eg, may be incorporated in a transceiver), one or more antennas (for example, antenna 106 in Fig. 1), and so on. Processor functions may include one or more processors. For example, the processor may include one or more of: a general purpose processor, a special purpose processor (eg, a baseband processor, a MAC processor, etc.), a digital signal processor (DSP), an application specific integrated circuit (ASIC), Field programmable gate array (FPGA) circuits, any other type of integrated circuit (IC), state machine, etc. One or more processors may or may not be integrated with one another. A processor (eg, one or more processors or a subset thereof) can be integrated with one or more other functions, such as other functions such as memory. The processor can perform signal encoding, data processing, power control, input/output processing, modulation, demodulation, and/or any other functionality that can cause the device to operate in a wireless environment, such as the WLAN of FIG. The processor can be configured to execute processing executable code (eg, instructions) including, for example, software and/or firmware indications. For example, the processing can be configured to execute computer readable instructions embodied in one or more processors (eg, a bank of chips including memory and processors) or memory. Execution of the instructions may cause the apparatus to perform one or more of the functions described herein.
The device may include one or more antennas. The device can employ multiple input multiple output (MIMO) technology. One or more antennas can receive radio signals. The processor can receive radio signals, such as via one or more antennas. One or more antennas may transmit radio signals (eg, based on signals transmitted from the processor).
The device may have memory that may include one or more devices for storing programming and/or materials, such as processor executable code or instructions (eg, hardware, firmware, etc.), electronic materials, databases, or Other digital information. The memory can include one or more memory cells. One or more memory units may be integrated with one or more other functions (eg, including other functions in a device such as a processor). Memory can include read only memory (ROM) (eg, erasable programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), etc.), random access memory Body (RAM), disk storage media, optical storage media, flash memory devices, and/or other permanent computer-ready media for storing information. The memory can be coupled to the processor. The processor can communicate with one or more memory entities, such as via a system bus, directly, and the like.
A WLAN in an Infrastructure Basic Service Set (IBSS) mode may have an Access Point (AP) for a Basic Service Set (BSS) and one or more stations (STAs) associated with the AP. The AP may have access or interface to a distribution system (DS) or another type of wired/wireless network that may carry traffic outside of the BSS or outside of the BSS. The 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 STAs arriving at destinations other than the BSS can be sent to the AP to be delivered to their respective destinations. The traffic between STAs in the BSS can be sent through the AP, where the source STA can send traffic to the AP and the AP can deliver traffic to the destination STA. The traffic between STAs in the BSS can be peer-to-peer. Such peer to peer traffic may be sent directly between the source and destination STAs, such as with a DLS using IEEE 802.11e Direct Link Setup (DLS) or IEEE 802.11z Tunnel DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may have no APs, and STAs may directly communicate with each other. This mode of communication can be an ad-hoc mode.
Using the operation of the IEEE 802.11 infrastructure mode, the AP can transmit beacons on fixed channels (eg, primary channels). The channel can be 20 MHz wide and can be the operating channel of the BSS. This signal can also be used by the STA to establish a connection with the AP. Channel access in an IEEE 802.11 system may be Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). In the operation of the infrastructure mode, each STA can listen to the primary channel. If the STA detects that the channel is busy, the STA can return. A STA can transmit in a given BSS at any given time.
In various countries of the world, dedicated spectrum can be allocated for wireless communication systems such as WLANs. The allocated spectrum (eg, below 1 GHz) can be limited in size and channel bandwidth. The spectrum can be segmented. Available channels may not be contiguous and cannot be combined for larger bandwidth transmission. A WLAN system (eg, built on the IEEE 802.11 standard) can be designed to operate in this spectrum. Given this spectrum limitation, WLAN systems may be able to support smaller bandwidths and lower data rates than HT and/or VHT WLAN systems (eg, based on IEEE 802.11n and/or 802.11ac standards).
It is possible to limit the allocation of spectrum in one or more countries. For example, in China, the 470-566 and 614-787 MHz bands can allow 1 MHz bandwidth. In addition to the 1 MHz bandwidth, 2 MHz and 1 MHz modes can be supported. The 802.11ah physical layer (PHY) can support 1, 2, 4, 8, and 16 MHz bandwidth.
The 802.11ah PHY can operate below 1 GHz. The 802.11ah PHY can be based on the 802.11ac PHY. The 802.11ac PHY can be down-clocked (eg, to match the narrow bandwidth required by 802.11ah). The 802.11 ac PHY can be clocked down by a factor of 10. Support for 2, 4, 8 and 16 MHz can be obtained with a 1/10 down time. Support for 1 MHz bandwidth can use PHY and Fast Fourier Transform (FFT) with size 32.
At 802.11ah, one or more STAs (eg, up to 6000 STAs, including devices like testers and sensors) can be supported in a Basic Service Set (BSS). STAs may have different supported uplink and downlink traffic requirements. For example, a STA may be configured to upload (eg, periodically upload) data to a server that causes uplink traffic. The STA can be queried by the server and/or can be configured by the server. When the server queries and/or configures the STA, the server may expect the queried data to arrive within the set interval. The application on the server or server may expect (eg, within a certain interval) to confirm the configuration performed. These traffic patterns can be different compared to traditional WLAN system traffic modes. In an 802.11ah system, one or more (eg, two) bits can be used in the PLCP header of the frame. One or more of the bits may indicate to the packet the type of response that is expected to be a response (eg, an early acknowledgement (ACK) indication). An ACK indication (eg, a two-ary 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: No ACK, 11: Frame not ACK, BA or Clear to Send (CTS).
Relay functionality (eg, as introduced in IEEE 802.11ah) can enable more efficient power usage. Relay functionality can reduce the transmission power consumed by the STA. Relay functionality can improve the STA's wireless link status. A two-way relay can include one or more (eg, two) hops. A transmission opportunity (TXOP) can be shared for relaying (eg, for explicit ACK exchange). The shared TXOP can reduce the number of channel contention. The frame control field can include relayed frame bits (eg, for TXOP operations). The Neighbor Discovery Protocol (NDP), ACK, and/or SIG fields may include relayed frame bits (eg, for TXOP operations).
The relay can receive frames (eg, valid frames). The relay may respond to the received frame with an ACK (eg, in a TXOP sharing operation). If the relay receives a valid frame, one or more of the following can be applied. If the relay receives a relayed frame bit set to 1, the ACK may be implicit in the next hop transmission after a short inter-frame space (SIFS). The relay may reply with an ACK after the SIFS with the trunk bit of the relay set to 1 and may continue the next hop data transmission after the SIFS. The relay may respond with an ACK after the SIFS with the trunk bit of the relay set to 0; the relay may not use the remaining TXOP.
The relay can set the trunk's frame bit to 1. For example, if the relay receives more data bits set to 0, the relay can set the relayed frame bit to 1.
A flow control mechanism for the relay can be provided. Support for the use of probe requests for relay discovery may be provided, which may include information on the AP-STA link budget. The STA can initiate the discovery process. The STA may select a relay based on one or more received probe responses. The relay entity may include a relay STA (R-STA), a relay AP (R-AP), and the like. The R-STA may be a non-AP STA. The R-STA can be a station that acts as an AP. The R-STA may have one or more capabilities including, for example, 4 address support (e.g., capable of transmitting and/or receiving and/or receiving from the associated root AP { to DS = 1, from DS = 1 } (frame), support for receiving and/or forwarding frames from R-AP, etc.
The R-AP can be an AP. The R-AP may have one or more capabilities including, for example, 4 address support, support for forwarding and receiving frames to/from the R-STA, and the ability to indicate R-AP (eg, by setting a bit) Or indicate the root-AP address and/or service setting identifier (SSID) in the beacon. One or more of the following may be applied to the R-AP, for example, related to 4-address support. The R-AP may send and/or receive to and/or from the associated STA's {to DS = 1, from DS = 1} frame (eg, based on the capabilities of the associated STA). The R-AP can receive a 4-bit address frame. The R-AP can forward a frame with 3 addresses to the associated STA.
Figure 2 depicts an example of an IEEE 802.11ah relay architecture. The relay AP may include the beacon and/or the SSID of the root AP in the probe response frame. The aggregated MAC Service Data Unit (A-MSDU) format can be used between the root AP and the relay AP (eg, for frame delivery). Messages (eg, reachable address messages) can be used to update the forwarded form.
Figure 3 depicts an example of a downlink relay from a AP (e.g., as a source) to a STA (e.g., as a destination) through a relay node. An explicit ACK can be used. The source AP may send a downlink data frame with an early ACK indicator bit. The early ACK indicator bit in the downlink data frame can be set to 00. The relay may send an ACK with an early ACK indicator bit set to 11 back to the source AP for the next output frame. In SIFS time, the relay can send data with different MCS and the early ACK indicator bit can be set to 00. The relay can buffer frames (for example, data frames). The frame can be buffered until its frame is delivered (eg, successfully delivered) or a predetermined number of retries (eg, retry limits). The destination STA in SIFS time may send an ACK with an early ACK indicator bit set to 10. When the source AP receives an ACK from the relay node, the source AP can remove the data frame from its buffer and can defer MAX_PPDU+ACK+2*SIFS before the next event.
Figure 4 depicts an example of an uplink relay from a STA (e.g., as a source) to an AP (e.g., as a destination) via a relay node. An explicit ACK can be used. As described in FIG. 4, the STA may transmit an uplink data frame with an early ACK indicator bit to the relay. The early ACK indicator bit can be set to 00. The relay can send an ACK and can set the early ACK indicator bit to 11 for the next output frame. In SIFS time, the relay can send data frames with different MCSs and can set the early ACK indicator bits to 00. The relay can buffer frames (for example, data frames). The frame can be buffered until the frame is delivered (eg, successfully delivered) or a predetermined number of retries (eg, retry limits) are reached. In SIFS time, the destination AP may send an ACK with an early ACK indicator bit set to 10. Upon receiving an ACK frame from the relay node, the STA may remove the data frame from its buffer and may defer MAX_PPDU+ACK+2*SIFS before the next event (eg, after receiving an ACK from the destination AP).
Figure 5 depicts an example of a relay operation using an implicit ACK. As shown in FIG. 5, the source node may send a downlink data frame having a response frame bit set to 11. A response frame bit set to 11 may indicate to the STA that another data frame may be behind. During SIFS time, the source node can receive the PHY SIG field with a response frame set to 00. The source node can check the PAID subfield in the PHG SIG field. The relay can send data frames with different MCSs. The relay can set the response frame bit to 00 and can set the PAID sub-field to the sub-field of the STA. The destination node may send an ACK with a response frame bit set to 10.
In IEEE 802.11ah, a short beacon frame format can be supported. A frame control type and/or subtype indication can be provided for the short beacon. Figure 6 depicts an example of a short beacon frame format. The short beacon may include one or more of the following fields: compressed SSID, timestamp, change sequence, time of the next complete beacon, access network options, and/or 3 digits included in the FC field. Yuan BW field. The compressed SSID field can be calculated as a cyclic redundancy check (CRC) for the SSID. The CRC can be calculated using the same function as the FCS that can be used to calculate the MPDU. The timestamp field can be 4 bytes long. The timestamp field can contain the 4 least significant bits (LSBs) of the AP timestamp. The change sequence field can be 1 byte long. Changing the sequence field can be increased when critical network information changes. The time field of the next complete beacon may indicate the time of the next complete beacon frame. The time field of the next complete beacon may be indicated in the next complete beacon frame as the higher 3 bytes of the 4 LSBs of the AP timestamp. If the AP periodically transmits a complete (eg, long) beacon frame, the time field of the next complete beacon may exist in the short beacon frame. The beacon frame may include an access network option field in the short message frame.
In IEEE 802.11, carrier-oriented WiFi may provide one or more of the following: fairness between BSS centers and BSS edge users, improved BSS edge performance, OBSS interference coordination, higher spectral efficiency and utilization, or cellular offloading .
The IEEE 802.11 High Efficiency WLAN (HEW) system can provide an increase in real world data traffic achieved by IEEE 802.11 users in a dense network with a large number of users and devices (eg, Wi-Fi hotspots, office buildings, etc.). Systems and methods for enhancing the performance of 802.11 PHYs and MACs at 2.4 and 5 GHz can also be provided. Enhanced performance can include one or more of the following: improved spectral efficiency and regional throughput, improved indoor and/or outdoor deployment (eg, intensive heterogeneous networks in the presence of interference sources, moderate to heavy user load APs) ) Real world performance.
One or more metrics may be considered by the STA for association when selecting an AP (eg, in a non-relay based WiFi network). The metric may include received signal strength, path loss, or link quality of the AP (eg, an AP that can transmit a beacon frame or a probe response frame).
The relay and associated functionality can be used to serve the STA (e.g., an STA that can suffer from a poor link budget when communicating directly with the AP). IEEE 802.11ah may provide relay and/or relay type STAs (eg, the possibility of handling poor link budget issues in the case of STA's macro type coverage). Relays can also be used in other WLAN variants.
When the relay is being used, the signal strength, path loss, or link quality of the received transmission beacon frame, the relay of the probe response frame (eg, R-AP, R-STA, etc.) may not provide the entire Sufficient information for the relay path (eg, from the source node to the destination node). Figure 7 depicts an example of relay path selection by the STA. The STA may receive a beacon or probe response frame from the relay node (eg, via path V1). The link quality between the STA and the relay node may be better than the link quality between the STA and the root AP (eg, via path U1). The path quality between the relay node and the root AP (eg, via path V2) may be better than the path quality between the STA and the root AP. Selecting the relay node based on the received beacon and/or the probe response frame quality may result in a relay path that may exhibit worse path loss and/or link quality than the direct path.
Figure 8 depicts an example of relay path selection using a root AP connected to more than one (e.g., two) relays. The source node (e.g., STA) may receive transmissions (e.g., via a beacon frame, a short beacon frame, or a probe response frame) from the relay node 2 (e.g., via path V3). The link quality between the STA and the relay node 2 may be better than the link quality between the STA and the relay node 1 (e.g., via path V1). The path loss between the AP and the relay node 2 may be greater than the path loss between the AP and the relay node 1. Selecting the relay node based on the link quality of the received transmission may result in a relay path via the relay node 2, which may show worse path loss and/or than the relay path via the relay node 1 Link quality. A valid AP discovery mechanism may allow the STA to discover the relay path, which may include considering the overall link quality.
In a relay-based WLAN architecture, a relay node can receive a source frame from a source node and can respond to the source node with an ACK. The relay node can send a data frame to the destination node. When the destination node receives the 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 may not be reliable (eg, may have a temporary interruption). When the link between the relay node and the destination node experiences an unfavorable condition, the data frame from the source node can be buffered at the relay node. Buffered data frames can cause buffer management issues (eg, buffer overflow). The source node may not know the link quality of the relay path between the relay node and the destination node. The source node can continue to transmit data to the relay node, which may increase congestion at the relay node. The flow control mechanism at the relay node (eg, an effective flow control mechanism) can prevent the path from being unreliable.
When a relay node is used, channel access contention can be reduced by sharing a transmission opportunity (TXOP) for relaying. This sharing of TXOPs can be provided in IEEE 802.11ah. By sharing the TXOP, the source node (eg, the initiator of the TXOP reservation) can reserve the TXOP for a 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 the relay node to the destination node. The TXOP of the shared relay can be truncated (eg, effectively truncated) when the actual transmission ends early at the relay node.
An information element (IE) or field indicating the link quality between the relay and the root AP may be transmitted in a transmission sent by a relay such as an R-AP (eg, to allow the end STA to determine the relay path) Overall link quality). The transmission can be a beacon frame, a short message frame, or a probe response frame. The compressed SSID of the root AP can be used in the transmission.
Figure 9 depicts an exemplary frame format for transmission in which a bit in the transmitted frame control field may indicate that the transmitter is a relay node (e.g., in place of the root AP). The transmission can be a short message frame. The transmission indicating that the transmitter is a relay node may be a beacon frame or a probe response frame (eg, the short message frame or the probe response frame may include similar fields as described in the example of the short message frame). When the frame control field is set to a value of 1, the transmitter can be a relay node. When the frame control field is set to a value of 0, the transmitter can be a non-relay node. As depicted in Figure 9, the bits in the transmitted frame control field may indicate the link quality between the relay and the root AP field in the transmission. A frame control field bit set to a value of 1 may mean that the field is present and a value of 0 may mean that the field does not exist. The reserved bits in the frame control field can be used to indicate the link quality between the relay and the root AP field. The link quality presence field or the relay indicator field can be implicitly signaled (eg, by methods such as CRC masking, scrambler initialization seed values, relative phase changes in the SIG field, or PLCP headers) Guide value or mode). The link quality presence bit or relay indicator bit in the frame control field may indicate that the link quality between the relay and the root AP may be included in the transmission. One or more octets can be used to relay the link quality between the root AP field. The link quality between the trunk and the root AP field may indicate the link quality (in dB) from 64 to 4096 levels. The link quality between the relay and the root AP field may indicate the link quality between the relay node and the root AP (eg, path loss, packet error/loss rate, transmission delay, etc.). Link quality (e.g., incremental link quality) estimates may be incremental for indicating the entire AP to STA link quality.
Figure 10 depicts an exemplary frame format for transmission in which the link quality between the relay and the root AP can be signaled by an IE (e.g., link quality IE between the relay and the root AP) (e.g., Signal transmission). The transmission can be a short message frame. The link quality transmission between the signaling relay and the root AP may be a beacon frame or a probe response frame (eg, a short message frame or a probe response frame may be included as described in the example of the short message frame) Similar field). The IE can be included in the transmission (eg, beacon frame, short message frame, or probe response frame). The link quality may have an explicit or implicit indication of a bit or relay that 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 links that provide a link between the relay and the root AP subfield. The octet. Link quality can represent multiple levels of link quality in dB (eg, 64 to 4096 levels).
Once the STA receives the transmission (eg, beacon frame, short message frame, or probe response frame), it can check the specific field or IE in the transmission to determine if the transmitted transmitter is a relay node. The STA may check for link quality presence or a relay indicator field (eg, if a link quality exists a bit exists). If the link quality is present or the relay indicator field bit is set to 1, the STA may know that the link quality between the relay and the root AP field may be included in the transmission.
The source node (eg, the STA with traffic to transmit) can determine one or more link qualities. For example, the source node can determine the quality of each link in the relay path (eg, determine whether to use relay instead of direct transmission to the destination node, determine which relay to use if multiple relays are available, etc.). Determining one or more link qualities, such as determining an overall link quality associated with a link from a STA to a relay node to a root AP, may include one or more of the following. The STA may check whether the link quality IE between the relay and the root AP is included in the transmission (eg, the STA may perform the check downwards in the case of checking or not checking the link quality presence or relaying the indicator field) . If the link quality IE between the relay and the root AP is included in the transmission, such a transmitter that can indicate the transmission is a relay node. The STA may receive a transmission (eg, a beacon frame, a short message frame, or a probe response frame) indicating the link quality between the relay node and the root AP, which may be represented as Q _AP-Relay (Q _AP-relay ). The field or IE in the received transmission can indicate the link quality. The STA can determine (e.g., estimate) the link quality of the relay node with itself. The STA may determine that it may be represented as Q based on the received transmission transmitted from the relay node. _STA-Relay (Q _AP-relay Link quality. The STA may determine (eg, calculate) the overall link quality of the indirect path (eg, STA to relay to root AP), eg, Q _{Relay path} (Q _{Relay path} ),for =Q _STA-Relay +Q _AP-Relay +. The indirect path can be a combined link. If the overall link quality Q _{Relay path} If the requirements are met, the STA (eg, scanning STA) may consider the relay node as a candidate (eg, for association). The STA may select an entity (eg, a relay node or a root AP) for transmission based on the overall link quality. The overall link quality meets the requirements (eg, above the threshold demand, for example if the overall link quality of the combined link is better and/or better than the link associated with the direct link with the root AP) When the overall link quality associated with the relay node is better, the selected entity may be a relay node.
Methods, systems, and tools are provided to describe relay flow control for relay functionality that can be applied to 802.11ah and other 802.11 systems (eg, HEW). Action frames (eg, flow control notification frames) can be defined. The relay node can perform flow control on the link between the source node and the relay node. If the link between the relay node and the destination node deteriorates, the relay node can perform flow control. Data frames from the source node can be buffered at the relay node and can cause congestion and/or buffer overflow (eg, more buffering may be needed when the link goes bad). The relay node can inform the source node about flow control. The relay node can notify the source node about flow control by sending a flow control notification frame. The flow control notification frame can be sent as a unicast frame in both uplink and downlink operations. The flow control notification frame can be sent as a broadcast frame in the downlink. The flow control node address can be signaled through the flow control notification frame. The flow control notification frame can signal the address of the relay node in the relay link (eg, between the destination node and the relay node). A relay node that signals in a flow control notification frame may experience unfavorable link quality.
The flow control notification frame can signal the address of the destination node. Data traffic for end STAs (eg, end STAs belonging to a relay link that has experienced a link problem) may be affected.
The flow control notification frame can be transmitted as a unicast or broadcast frame. The Transmitter Address (TA) field in the MAC header of the frame can be set to the relay node address. The flow control information in the flow control notification frame may refer to a relay node identified by the TA address. Figure 11 depicts an exemplary frame format for a flow control notification frame. The classification field can be set to represent the value of the two-point jump relay (eg, can be specified in the standard). The action (eg, two-point jump relay action) field can be set to represent the value of the flow control notification (eg, a unique value). The action field can be set as specified in the standard.
Figure 12 depicts an example of a flow control notification element. As depicted in FIG. 12, the element ID field can 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 classification (AC) (eg, background (BK), best effort (BE), video (VI), and sound (VO)) may indicate that the application is relaying on the corresponding AC The duration of the node's flow control. The time unit of the flow control duration can be M μs. The flow control data rate field for each AC (eg, BK, BE, VI, and VO) may indicate the data rate that the end STA can transmit to the relay node during the flow control duration of the corresponding AC (eg, maximum data) rate).
The TA address in the MAC header may indicate (eg, identify) the relay node to which the received flow control information is applied. Due to the two-point hopping relay architecture (eg, where the relay node can be associated with a root AP), the TA address in the MAC header can provide sufficient information to identify congestion that may have experienced an uplink condition Or a relay link of unfavorable link quality. Using the TA address in the MAC header to identify the relay link can reduce signaling overhead. In a downlink where multiple end STAs may be associated with one relay node, the TA address in the MAC header may not identify (eg, uniquely identify) that the end STA and the relay node may have experienced congestion or A relay link with unfavorable link quality. The flow control notification frame may signal the address of the relay node in a relay link that may have experienced unfavorable link quality (e.g., in uplink operation). The flow control notification frame can signal the address of the destination node (eg, in downlink operation). The flow control notification element can be piggybacked on the data frame from the relay node to the source node or on the control frame.
For example, a flow control notification element as described in FIG. 13 can be used. The flow control notification element as described in FIG. 13 may specify a flow control duration and a data rate limit for a combination of access categories (eg, instead of providing one for each of the ACs).
Figure 14 depicts an exemplary frame format for a flow control notification frame in which the address of the destination node can be signaled in a flow control notification frame. As described in FIG. 14, the classification field can be set to a value that can represent a two-point jump relay (eg, as specified in the standard). The action (eg, two-point jump relay action) field can be set to represent the value of the flow control notification (eg, as specified in the standard).
Figure 15 depicts an exemplary design of a flow control notification element. As depicted in Figure 15, the Element ID field can be set to a value that can represent a flow control notification element (eg, 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 destination node address (eg, the end STA address) may be set to the 6-bit MAC address of the destination node (eg, the end STA). The flow control notification frame may indicate the received flow control information, which may be applied to the relay node identified by the TA address in the MAC header. The flow control duration field for each access classification (AC) (eg, BK, BE, VI, and VO) may indicate the duration of flow control that may be applied to the relay node of the corresponding AC. The time unit of the flow control duration can be M μs. The flow control data rate field for each AC (eg, BK, BE, VI, and VO) may indicate the data rate that the end STA can transmit to the relay node during the flow control duration of the corresponding AC (eg, maximum data) rate).
Flow control can include one or more of the following. The relay node can monitor the buffer occupancy at the relay node. The relay node can monitor the link quality between the relay and the destination node. The relay node can determine that flow control should be applied (eg, to ease the congestion of the identity). The relay node can send a flow control notification frame to the source node. The flow control notification frame can include flow control parameters, such as described herein. The source node can identify the address of the node to which traffic control can be applied (eg, when receiving a flow control notification frame). The address can be a relay address (e.g., in an uplink operation). The address can be (eg, in the downlink) the relay address and the end STA address. The source node can obtain information from the flow control notification element. The source node can take action based on this information in the flow control notification element. If the flow control duration field is received for AC, the source node may stop (eg, via a relay node for the duration value in the received flow control notification element) to transmit the corresponding AC targeted at the destination address. Information frame. The end STA can directly transmit the data frame to the root AP without passing through the relay node (eg, if the link quality between the end STA and the root AP is acceptable). The source node may limit (eg, via a relay node that controls the duration value in the notification element for the received traffic) to the data rate of the AC (eg, the corresponding AC) targeted at the destination address. If the flow control duration field and the flow control data rate are received for AC, the source node can limit the data rate. The flow control limit can end at the source node (eg, when the flow control duration expires). The source node may resume transmission (eg, normal transmission) of the data frame to the destination node, eg, via the relay node.
The data frame can include a contention free end (CF-end) (eg, to allow the relay node to truncate unused TXOPs). One or more of the following can be applied. Bits reserved in the SIGA field (eg, one bit) can be used (eg, again) to indicate CF-end. The data frame receiver can reset the network allocation vector (NAV) at the end of the duration 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. Reserved bits in the frame control field of the MAC header can be used (eg, again) to indicate CF-end. The data frame receiver can reset the NAV at the end of the duration 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, implicit signaling). The CF-End indication may be signaled using one or more of the following: a CRC mask, a scrambler initialization seed value, a relative phase change in the SIG field, or a pilot value or pattern in the PLCP header.
In the case of TXOP, a two-point hop request for transmit/clear transmission (RTS/CTS) may establish and/or may preserve the duration of the relay frame exchange between the source node, the relay node, and the destination node. (eg, the entire duration) of the TXOP. The duration from the relay node transmitting the data frame to the destination node can be assumed to be the worst case. The duration of transmission of the data frame from the relay node to the destination node can be estimated (eg, conservative estimation). The source node can begin data transfer after the SIFS time (eg, immediately following receipt of the CTS frame from the relay node).
The relay node can process the received data frame from the source node. (For example, if the received data frame is correctly decoded and an explicit ACK is used) the relay node can send an ACK frame. (eg, if an implicit ACK is used) the STA may not send an ACK frame. (eg, if an explicit ACK is used and the received data frame is not correctly decoded), after transmitting the data frame, the source node may not receive the ACK by the time of SIFS time + ACK_time. (eg, if an implicit ACK is used and the received data frame is not decoded correctly) the source node may not receive an implicit ACK. A data frame from the relay node with an ACK indication field set to 00 may indicate an implicit ACK. The source node can release the TXOP by sending a CE-end frame. The source node can retransmit the data frame. The relay node and/or the destination node may send a CF-end frame upon receiving a CF-end from the source node.
The relay node can send a data frame to the destination node. The relay node may set the CF-end indication in the data frame to 1 or positive and may set the duration field in the MAC header of the data frame (eg, if the duration of the data frame) Plus SIFS time and ACK_time or short ACK_time is shorter than the remaining TXOP). The duration field in the MAC header can be determined using the length of the data frame and the data rate used for transmission.
The destination node can process the received data frame 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 indication in the received data frame. (eg, if the CF-end indication is affirmative) the destination node may release the TXOP and may reset the NAV of the STA that is close to the destination node. The destination node can send a CF-end frame. The destination node can set the ACK indicator field in the output ACK frame (for example, set to 10). When the ACK indicator field is set to "10" in the output ACK frame, the destination node may not send the CF-end frame.
(eg, once a data frame with a positive CF-end indication is received from the relay node before the current TXOP expires) the source node may send a CF-end frame after the SIFS time plus time (eg, necessary time) Covers the frame sent by the destination node. The frame sent by the destination node may be an ACK frame or an ACK frame plus a CF-end frame. The source node can send the CF-end frame immediately after the duration of the signalling in the received data frame.
Figures 16 and 17 depict exemplary TXOP operations. Figure 16 depicts an example of a TXOP operation utilizing an explicit ACK. Figure 17 depicts an example of a TXOP operation that utilizes an implicit ACK. As depicted in Figure 16, the relay node may send an ACK (e.g., an explicit ACK) to the source node (e.g., after receiving the data frame from the source node). The relay node may send an ACK to the source node before forwarding the data frame with the CF-end bit to the destination node. As depicted in Figure 17, the relay node may send a data frame with a CF-end bit to the destination node (e.g., after receiving the data frame from the source node). The relay node can send the data frame to the source node without sending an ACK.
Although the above features and elements are described in a particular combination, one of ordinary skill in the art can understand that each feature or element can be used alone or in any combination with other features and elements. In addition to the 802.11 protocols described herein, the features and elements described herein can be applied to other wireless systems. In addition, the methods described herein can be implemented in a computer software, hardware or firmware, and the computer software, hardware or firmware is incorporated into a computer readable medium executed 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), scratchpad, cache memory, semiconductor storage devices, such as internal hard drives and removable disks. Magnetic media, magneto-optical media, optical media such as CD-ROM discs and digital versatile discs (DVD). A processor associated with the software can be used to implement the radio frequency transceiver for use in a WTRU, WTRU, terminal, base station, RNC, or any host computer.

AP‧‧‧ access point

STA‧‧‧ Platform

Claims (1)

1. A method of determining a link quality, the method comprising:
Receiving a transmission indicating that the transport entity is a relay node, wherein the transmission indicates a first link quality associated with a link between the relay node and an access point (AP);
Determining a second link quality associated with a link between a station (STA) and the relay node;
Determining an overall link quality associated with a link from the STA to the relay node to the root AP; and selecting an entity to associate based on the overall link quality.
2. The method of claim 1, wherein the transmission is a beacon frame, a short message frame, or a probe response frame.
3. The method of claim 2, wherein determining the second link quality is estimated by the STA based on the received transmission.
4. The method of claim 1, wherein the method further comprises determining the first link quality.
5. The method of claim 4, wherein the overall link quality is associated with a combination of the first link quality and the second link quality.
6. The method of claim 1, wherein the method further comprises determining whether the overall link quality meets a requirement.
7. The method of claim 6, wherein the entity selected when the overall link quality satisfies the demand is the relay node.
8. The method of claim 1, wherein the indication that the transmitting entity is the relay node is explicitly signaled in an information element.
9. 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 a frame of the transmission.
10. The method of claim 1, wherein the method further comprises transmitting data to the relay node and transmitting an indication that the data is to be relayed to the AP.
11. A station (STA), the STA comprising:
A processor configured to:
Receiving a transmission indicating that the transport entity is a relay node, wherein the transmission indicates a first link quality associated with a link between the relay node and an access point (AP);
Determining a second link quality associated with a link between a station (STA) and the relay node;
Determining an overall link quality associated with a link from the STA to the relay node to the root AP; and selecting an entity to associate based on the overall link quality.
12. The STA of claim 11, wherein the transmission is a beacon frame, a short message frame, or a probe response frame.
13. The STA of claim 12, wherein the processor is further configured to estimate the second link quality based on the received transmission.
14. The STA of claim 11, wherein the processor is further configured to determine the first link quality.
15. The STA of claim 14, wherein the overall link quality is associated with a combination of the first link quality and the second link quality.
16. The STA of claim 11, wherein the processor is further configured to determine whether the overall link quality meets a requirement.
17. The STA of claim 16, wherein the selected entity is the relay node when the overall link quality satisfies the demand.
18. The STA of claim 11, wherein the transmission indicating that the transmitting entity is the relay node is explicitly signaled in an information element.
19. The STA of claim 11, wherein the transmission indicating that the transmitting entity is the relay node comprises the presence of the first link quality in a frame of the transmission.
20. The STA of claim 11, wherein the processor is further configured to send data to the relay node and send an indication that the data will be relayed to the AP.