BSS Color Enhanced Transmission (BSS-CET) in WLAN

Abstract

To disclose a system, a method, and means for transmission scheduling.SOLUTION: A station (STA) in its own basic service set (BSS) receives a transmission frame from an overlapping BSS (OBSS). The STA can decode a preamble of the received transmission frame. The STA can determine, for example, by using the decoded preamble, OBSS information and a transmit scheme associated with the OBSS. On a condition that the transmit scheme associated with the OBSS is orthogonal frequency divisional multiple access (OFDMA), the STA in its own BSS may indicate to its access point (AP) that one or more channels or sub-channels are available or not available for transmission.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to BSS color enhanced transmission (BSS-CET) in WLANs. [Background technology]

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62 / 101,645, filed January 9, 2015, the contents of which are incorporated herein by reference.

[0003] With the rapid increase in the number of Institute of Electrical and Electronics Engineers (IEEE) 802.11 devices (stations (STAs) and / or access points (APs)) being added to wireless local area network (WLAN)-based networks, dense WLAN deployments are becoming commonplace. Such dense WLAN deployments face significant performance challenges due to factors including, for example, interference, congestion, and low throughput.

[0004] Existing WLAN capabilities, such as for basic service sets (BSSs), as used in IEEE 802.11ah, may not be adequate for such dense WLAN deployments. Enhanced BSS color formats and related mechanisms may be required to improve performance in such dense WLAN deployments. Summary of the Invention [Means for solving the problem]

[0005] Systems, methods, and means are disclosed that can improve performance in densely deployed WLANs. A station (STA) within its own basic service set (BSS) can receive a transmission frame from an overlapping BSS (OBSS). The STA can decode a preamble from the received transmission frame. The STA can use the decoded preamble (e.g., only the decoded preamble) to determine OBSS information and / or a transmission scheme associated with the OBSS. The transmission scheme can include one or more of orthogonal frequency division multiplexing (OFDM), orthogonal frequency division multiple access (OFDMA), BSS silencing, interference avoidance with sectorized transmission, or OFDMA with band silencing. The transmission frame can include a transmitting node or BSS identification. The transmitting node or BSS identification can indicate whether the transmitting node or BSS identification is for downlink transmission or uplink transmission.

[0006] The determined transmission scheme associated with the BSS may be Orthogonal Frequency Division Multiple Access (OFDMA). In such a case, the STA may indicate to its associated access point (AP) within its own BSS one or more channels or subchannels that are available for transmission and / or one or more channels or subchannels that are unavailable for transmission. The STA may send the channel information to the AP within its own BSS, for example, in response to a transmission schedule and / or with an uplink request.

[0007] The determined transmission scheme associated with the OBSS may be orthogonal frequency division multiplexing (OFDM). In such a case, the STA may determine that the channel is unavailable for transmission. The STA may set the channel to busy, for example, when the OBSS information indicates that the STA is not robust to OBSS interference. The STA may set the channel to idle, for example, when the OBSS information indicates that the STA is robust to OBSS interference. The STA may transmit on the channel set to idle. [Brief explanation of the drawings]

[0008] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, in which:

[0009] [Figure 1] 1 is a diagram of an exemplary wireless local area network (WLAN) system. [Figure 2] FIG. 1 illustrates an example of enhanced distributed channel access (EDCA) operation. [Figure 3] FIG. 10 is a diagram illustrating an example of a sub-1 GHz (S1G) capability information field. [Figure 4] FIG. 1 is a diagram illustrating an example of a SIG-1 frame structure. [Figure 5] FIG. 1 illustrates an example of clear channel assessment (CCA) thresholds by basic service set (BSS) color. [Figure 6] FIG. 1 illustrates an exemplary overlapping orthogonal frequency division multiplexing (OFDM) transmission of an intended signal in the presence of strong interference. [Figure 7] FIG. 1 illustrates an example media access control (MAC) frame format for a feedback packet. [Figure 8] 1 illustrates an example feedback information of a STA to its access point (AP) using a non-overlapping secondary channel. [Figure 9] FIG. 1 illustrates an example spatial quadrature feedback. [Figure 10] FIG. 1 illustrates an example demodulated interfering symbol mixed with an intended symbol. [Figure 11] FIG. 1 illustrates an example network illustrating cancellation and deferred ACK. [Figure 12] FIG. 10 illustrates an example of a deferred ACK operation. [Figure 13] FIG. 10 is a diagram illustrating an example of an ACK operation. [Figure 14] FIG. 1 illustrates an example of uplink / downlink (UL / DL) orthogonal frequency division multiple access (OFDMA). [Figure 15] FIG. 1 is a diagram illustrating an example of UL / DL OFDMA packet exchange type 1. [Figure 16] FIG. 1 is a diagram illustrating an example of UL / DL OFDMA packet exchange type 2. [Figure 17] A diagram showing an example of UL / DL OFDMA packet exchange type 3. [Figure 18] FIG. 1 is a diagram illustrating an example of UL / DL OFDM. [Figure 19] FIG. 1 illustrates an example of UL / DL OFDM packet exchange. [Figure 20] FIG. 1 illustrates an example of OFDMA with peer-to-peer transmission using enhanced BSS color. [Figure 21] FIG. 1 illustrates an example of packet switching. [Figure 22] FIG. 1 illustrates overlapping BSS interference, an exemplary interference cancellation transceiver. [Figure 23] FIG. 10 illustrates an example of an OBSS reporting element. [Figure 24] FIG. 10 is a diagram showing an example of a color announcement (sub) element. [Figure 25A] 1 is a diagram of an example communication system in which one or more embodiments may be implemented. [Figure 25B] 25B is a diagram of an example wireless transmit / receive unit (WTRU) used within the communication system of FIG. 25A. DETAILED DESCRIPTION OF THE INVENTION

[0010] A detailed description of exemplary embodiments will now be set forth in connection with various figures. While this description provides detailed examples of possible implementations, it should be noted that the details are illustrative and in no way limit the scope of the present application.

[0011] A WLAN in infrastructure basic service set mode can have an access point (AP) for a basic service set (BSS) and one or more stations (STAs) associated with the AP, as shown by example in FIG. 1. The AP can have access or interface to a distribution system (DS) or to other types of wired / wireless networks that can carry traffic within or outside the BSS. Traffic to a STA can originate from outside the BSS, arrive through the AP, and be delivered to the STA. Traffic originating from a STA to a destination outside the BSS can be sent to the AP to be delivered to the respective destination. Traffic between STAs within a BSS can be sent through the AP, with the source STA sending traffic to the AP, and the AP delivering the traffic to the destination STA. Traffic between STAs within a BSS can be peer-to-peer traffic. Such peer-to-peer traffic can be sent directly between the source and destination STAs by direct link setup (DLS), for example, using IEEE 802.11e DLS or IEEE 802.11z tunneled DLS (TDLS). A WLAN using the Independent BSS (IBSS) mode may not have an AP, and STAs can communicate directly with each other. This communication mode may be called ad-hoc mode.

[0012] 1 illustrates exemplary wireless local area network (WLAN) devices. One or more of the devices can be used to implement one or more of the features described herein. A WLAN can include, but is not limited to, an access point (AP) 102, stations (STAs) 110, and STAs 112. The STAs 110 and 112 can be associated with the AP 102. A WLAN can be configured to implement one or more protocols of the IEEE 802.11 communications standard, which can include channel access methods such as DSSS, OFDM, and OFDMA. A WLAN can operate in certain modes, such as infrastructure mode, ad hoc mode, etc.

[0013] A WLAN operating in infrastructure mode may include one or more APs that communicate with one or more associated STAs. An AP and the STAs associated with the APs may comprise a basic service set (BSS). For example, AP 102, STA 110, and STA 112 may comprise BSS 122. An extended service set (ESS) may include one or more APs (with one or more BSSs) and the STAs associated with the APs. An AP may have access to and / or an interface to a distribution system (DS) 116, which may be wired and / or wireless and may carry traffic to and / or from the AP. Traffic originating from outside the WLAN and destined for a STA within the WLAN may be received at an AP within the WLAN, which may forward the traffic to the STA within the WLAN. Traffic originating from a STA within the WLAN and destined for a destination outside the WLAN, e.g., server 118, may be sent to an AP within the WLAN, which may forward the traffic to the destination via DS 116 to network 114, e.g., server 118. Traffic between STAs within the WLAN may be routed through one or more APs. For example, a source STA (e.g., STA 110) may have traffic intended for a destination STA (e.g., STA 112). STA 110 may send traffic to AP 102, and AP 102 may send traffic to STA 112.

[0014] A WLAN can operate in ad-hoc mode. An ad-hoc mode WLAN can 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, and such communication is not routed through an AP).

[0015] IEEE 802.11 devices (e.g., IEEE 802.11 APs in a BSS) can use beacon frames to announce the presence of a WLAN network. An AP, such as AP 102, can transmit beacons on a channel, e.g., a fixed channel, such as a primary channel. STAs can establish connections with the AP using a channel, such as the primary channel.

[0016] The STA and / or AP can use a carrier sense multiple access with collision avoidance (CSMA / CA) channel access mechanism. In CSMA / CA, the STA and / or AP can sense the primary channel. For example, if the STA has data to send, the STA can sense the primary channel. If the primary channel is detected to be busy, the STA can back off. For example, a WLAN, or a portion thereof, can be configured to allow one STA to transmit at a given time, e.g., within a given BSS. Channel access can include RTS and / or CTS signaling. For example, an exchange of request-to-send (RTS) frames can be sent by a sending device, and clear-to-send (CTS) frames can be sent by a receiving device. For example, if the AP has data to send to the STA, the AP can send an RTS frame to the STA. When the STA is ready to receive the data, the STA can respond with a CTS frame. The CTS frame can include a time value that can warn other STAs to refrain from accessing the medium while the AP that initiated the RTS can transmit its data. Upon receiving a CTS frame from the STA, the AP can send data to the STA.

[0017] Devices can reserve spectrum through the Network Allocation Vector (NAV) field. For example, in IEEE 802.11 frames, the NAV field can be used to reserve a channel for a certain period of time. A STA that wants to transmit data can set its NAV at a time when it expects to use the channel. When a STA sets its NAV, the NAV can be set for the associated WLAN or a subset thereof (e.g., BSS). Other STAs can count down the NAV to zero. When the counter reaches a value of zero, the NAV function can inform other STAs that the channel is now available.

[0018] A device in a WLAN, such as an AP or STA, may include one or more of a processor, memory, a radio receiver (receiver) and / or transmitter (transmitter) (which may, for example, be combined into a transceiver), one or more antennas (e.g., antenna 106 of FIG. 1), etc. Processor functionality may comprise one or more processors. For example, a processor may comprise one or more of a general-purpose processor, a special-purpose processor (e.g., a baseband processor, a MAC processor, etc.), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. One or more processors may or may not be integrated with each other. A processor (e.g., one or more processors, or a subset thereof) may be integrated with one or more other functions (e.g., other functions, such as memory). A processor may perform signal coding, data processing, power control, input / output processing, modulation, demodulation, and / or any other function that may enable a device to operate in a wireless environment, such as the WLAN of FIG. 1C. A processor can be configured to execute processor-executable code (e.g., instructions), including, for example, software and / or firmware instructions. For example, a processor can be configured to execute computer-readable instructions contained on one or more of the processor (e.g., a chipset including a memory and a processor) or memories. Execution of the instructions can cause the device to perform one or more of the functions described herein.

[0019] The device may include one or more antennas. The device may use multiple-input multiple-output (MIMO) techniques. The one or more antennas may receive wireless signals. The processor may receive wireless signals, for example, via one or more antennas. The one or more antennas may transmit wireless signals (e.g., based on signals sent from the processor).

[0020] A device may have memory, which may include one or more devices for storing programming and / or data, such as processor-executable code or instructions (e.g., software, firmware, etc.), electronic data, databases, or other digital information. The memory may include one or more memory units. The one or more memory units may be integrated with one or more other functions (e.g., other functions included in the device, such as a processor). The memory may include read-only memory (ROM) (e.g., erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), etc.), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, and / or other non-transitory computer-readable media for storing information. The memory may be coupled to the processor. The processor may communicate with one or more entities of the memory, for example, via a system bus or directly.

[0021] A WLAN in Infrastructure Basic Service Set (IBSS) mode can have an access point (AP) for a basic service set (BSS) and one or more stations (STAs) associated with the AP. The AP can have access or an interface to a distribution system (DS) or other type of wired / wireless network that can carry traffic within or out of the BSS. Traffic to a STA can originate from outside the BSS, arrive through the AP, and be delivered to the STA. Traffic originating from a STA to a destination outside the BSS can be sent to the AP to be delivered to the respective destination. Traffic between STAs within a BSS can be sent through the AP, with the source STA sending traffic to the AP, and the AP delivering the traffic to the destination STA. Traffic between STAs within a BSS can be peer-to-peer traffic. Such peer-to-peer traffic can be sent directly between the source and destination STAs via direct link setup (DLS), for example, using IEEE 802.11e DLS or IEEE 802.11z tunneled DLS (TDLS). A WLAN using the Independent BSS (IBSS) mode may not have an AP, and STAs can communicate directly with each other. This communication mode may be called ad-hoc mode.

[0022] Using the IEEE 802.11 infrastructure mode of operation, an AP can transmit beacons on a fixed channel, usually the primary channel. This channel can be 20 MHz wide and can be the operating channel of the BSS. This channel can also be used by STAs to establish connections with the AP. Channel access in IEEE 802.11 systems can be carrier sense multiple access with collision avoidance (CSMA / CA). In this mode of operation, STAs, including the AP, can sense the primary channel. If the channel is detected to be busy, the STA can back off. If the channel is detected to be free, the STA can acquire the channel and transmit data.

[0023] In IEEE 802.11n, high-throughput (HT) STAs can use 40 MHz-wide channels for communication, which can be achieved, for example, by combining a primary 20 MHz channel with adjacent 20 MHz channels to form a 40 MHz-wide contiguous channel.

[0024] In IEEE 802.11ac, a very high throughput (VHT) STA can support channels of, for example, 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz width. 40 MHz and 80 MHz channels can be formed, for example, by combining contiguous 20 MHz channels. A 160 MHz channel can be formed, for example, by combining eight contiguous 20 MHz channels or two non-contiguous 80 MHz channels (e.g., referred to as an 80+80 configuration). In the 80+80 configuration, after channel encoding, the data can be passed through a segment parser that can split it into two streams. An inverse fast Fourier transform (IFFT) and time-domain processing can be performed separately on each stream. The streams can be mapped to two channels, and the data can be transmitted. At the receiver, this mechanism is reversed, and the combined data can be sent to the MAC.

[0025] IEEE 802.11af and IEEE 802.11ah can operate in sub-1 GHz bands. For these specifications, the channel operating bandwidth can be reduced compared to that used in IEEE 802.11n and IEEE 802.11ac. IEEE 802.11af can operate in television white space (TVWS) spectrum, and IEEE 802.11ah can support 1 MHz, 2 MHz, 4 MHz, 8 MHz, and / or 16 MHz bandwidths using non-TVWS spectrum, for example. For example, 802.11ah can support meter-type control (MTC) devices in macro coverage areas. MTC devices can have limited capabilities, including, for example, limited bandwidth and support for long battery life.

[0026] A WLAN system may support multiple channels and / or channel widths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, as well as a channel that can be designated as a primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by some or all STAs in a BSS. The bandwidth of the primary channel may be limited by the STA (e.g., some or all STAs operating in a BSS) that can support the smallest bandwidth operating mode. In the 802.11ah example, for example, if there is a STA (e.g., an MTC-type device) that supports (e.g., only supports) the 1 MHz mode, the primary channel may be 1 MHz wide, even if the AP and other STAs in the BSS may support 2 MHz, 4 MHz, 8 MHz, 16 MHz, or other channel bandwidth operating modes. Some or all carrier sensing and NAV settings may depend on the status of the primary channel, such that if the primary channel is busy, for example by supporting (e.g., only) a 1 MHz operating mode that the STA transmits to the AP, then the entire available frequency band may be considered busy even though most of it may be idle and / or available.

[0027] For example, in the United States, the available frequency band that can be used by IEEE 802.11ah can be from 902 MHz to 928 MHz. For example, in South Korea, this can be from 917.5 MHz to 923.5 MHz. For example, in Japan, this can be from 916.5 MHz to 927.5 MHz. The total bandwidth available for IEEE 802.11ah can be from 6 MHz to 26 MHz and can depend on the country code.

[0028] Enhanced Distributed Channel Access (EDCA) can be an extension of the Distributed Coordination Function (DCF), which was introduced in the 802.11 standard to support prioritized Quality of Service (QoS). Figure 2 shows the operation of EDCA, for example, as provided in the IEEE 802.11n standard.

[0029] The Point Coordination Function (PCF) can use contention-free channel access. The PCF can support time-limited services and polling by the AP. As shown in Figure 2, the AP can send a polling message after waiting for the PIFS. If the client has nothing to send, it can return a null data frame. Because the PIFS is smaller than the DIFS, it can lock out all asynchronous traffic. The PCF can be deterministic and fair, and can be efficient for both low duty cycle and congested or bursty traffic.

[0030] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 High-Efficiency WLAN (HEW) Study Group (SG) has been exploring ways to enhance the Quality of Experience (QoE) for a wide range of wireless users in many usage scenarios, including high-density scenarios in the 2.4 GHz and 5 GHz bands. Use cases that support high-density deployment of APs and STAs, as well as related radio resource management (RRM), are being considered by the HEW SG.

[0031] Applications for HEW include, but are not limited to, high user density scenarios such as data distribution for stadium events, train stations, or corporate / retail environments, evidence of increasing dependency on video distribution, and emerging usage scenarios including wireless services for medical applications.

[0032] For example, based on the work in the HEW Study Group (SG), the IEEE 802.11ax Task Group (TG) was established based on a Project Approval Request (PAR) and Criteria for Standards Development (CSD).

[0033] IEEE 802.11ah can provide basic service set (BSS) color and / or partial association identification (partial AID). BSS color is a mechanism in 802.11ah to allow STAs to distinguish, for example, whether downlink transmissions are from their own or other BSSs. Figure 3 shows the S1G capability information field. As shown in Figure 3, BSS color can be transmitted in the sub-1 GHz (S1G) capability information field to allow STAs to identify the color of APs with which they may negotiate.

[0034] Figure 4 shows an example of a SIG-1 frame structure. The BSS color can be transmitted in the ID field of the SIG-1 field of a packet (e.g., every packet) that can be transmitted as part of the preamble. This can allow a STA to roughly identify the transmitting BSS by decoding the preamble. The BSS color does not have to be unique. A STA can use the BSS color to determine that a signal does not belong to the BSS with which it is associated. A STA may not be certain that a transmitted signal belongs to its own BSS.

[0035] The BSS color can be placed in the TXVECTOR / RXVECTOR parameters. The BSS color can be used to help the receiving STA identify the BSSs from which reception can occur. For example, when reception cannot be from a BSS with which the STA can associate, the receiving STA can reduce power consumption by terminating the reception process.

[0036] The partial AID can be a mechanism that can be used to identify the recipient of a transmitted frame from a STA. The partial AID can provide an abbreviated indication of the intended recipient of a PLCP service data unit (PSDU). The partial AID can be carried, for example, in the Receiver Address (RA) when the frame is destined for a STA, or in the partial BSS ID when the packet is destined for an AP.

[0037] The combination of BSS color and partial AID can assist in member physical protocol data unit (PPDU) identification and can be used in 802.11ah for one or more of: power saving, detecting spatially orthogonal transmissions during OBSS / non-OBSS transmissions, in CCA operation, or in response indication deferral.

[0038] BSS color and / or PAID can be used in IEEE 802.11ah. For example, BSS color can be used in IEEE 802.11ah to achieve power savings as described herein. The TXVECTOR parameter COLOR can be used to assist a receiving STA in identifying the BSS from which the reception occurred. For example, when the reception is not from a BSS with which the STA is associated, the receiving STA can reduce power consumption by terminating the reception process.

[0039] Spatially orthogonal transmission (e.g., using sectorization) and BSS color may be mentioned herein. The RXVECTOR parameter COLOR may be utilized to detect the spatially orthogonal (SO) condition, for example, by categorizing received PPDUs between BSS transmissions (e.g., same BSS transmissions) and OBSS transmissions. If the initial sector indicator is equal to 0, the OBSS STA may not check for the spatial orthogonal condition.

[0040] If the initial sector indicator is 1, the initial sector indicator field may indicate that the NDP CTS frame may be followed by a sectorized beam frame exchange. If the initial sector indicator is 0, it may indicate that the NDP CTS frame may not be followed by a sectorized beam frame exchange.

[0041] CCA operation using BSS color / PAID can be effected. For example, if the STA determines that the transmission is associated with the same BSS as the STA is associated with, the STA can set the channel to a busy status. If the STA determines that the transmission is associated with an OBSS, for example, if the CCA exceeds a minimum CCA sensitivity level, the STA can set the channel to busy.

[0042] Response indication deferral using member PPDU identification can be effected. For example, in IEEE 802.11ah, a virtual carrier sense mechanism can be added to the CSMA / CA algorithm called response indication deferral (RID), for example, when the NAV counter or RID counter is not zero and the indication is that the medium is busy. The counters can be modified, for example, based on whether the transmission is from within the BSS or from the OBSS.

[0043] BSS color in IEEE 802.11ax can be introduced. Clear channel assessment thresholds and transmit power control (CCA / TPC) can be adjusted, for example, based on the BSS color. A BSS color implementation can use changes to the CCA of the STAs receiving the signal. Adjusting CCA (e.g., CCA alone) cannot improve system spectral efficiency. For example, to increase the use of limited frequency-time resources, joint CCA threshold and TPC adjustments can be utilized. Incorporating TPC can result in implementation and / or signaling changes when transmit power control is used and / or when information about the receiver sensitivity of the desired receiver is known.

[0044] Advanced spatial reuse can be achieved using BSS color. System spectral efficiency can be improved by using BSS color. BSS color can enable spatial reuse between adjacent or overlapping BSSs (OBSSs). Joint CCA and TPC coordination can enable the use of spatial reuse. CCA and TPC cannot fully protect spatially reused transmissions and / or avoid collisions between OBSS transmissions. To achieve this goal and / or enable modified receiver designs, signaling between transmitters and receivers using BSS color information can be used.

[0045] Transmission-scheme-specific colors can be provided. For example, the BSS color scheme in IEEE 802.11ah can include transmission over sub-1 GHz frequency bands. IEEE 802.11ah can provide extended coverage range, enhanced power savings, and / or support for a large number of devices. Next-generation WLAN systems can have one or more characteristics, such as dense deployment, high spectral efficiency, and / or existing BSS color formats cannot meet the new requirements. One or more transmission schemes, such as OFDM, OFDMA, MU-MIMO, etc., can be supported. To better serve these goals, transmission-scheme-specific BSS color formats or systems can be utilized.

[0046] BSS color changes and coordination can be provided. For example, when a BSS is established, a value associated with the BSS color can be selected. To provide efficient interference handling, the color of the BSS can be selected in coordination with surrounding overlapping BSSs. A BSS can select a different BSS color due to interference from an overlapping BSS. An AP can announce a BSS color change to one or more STAs associated with the AP. BSS color changes and / or coordination can be utilized to provide optimized interference handling.

[0047] The sending and receiving addresses of the nodes in the examples described herein may be placed in the packet, for example in the MAC header or in the PHY SIG, to allow identification of the OBSS transmission.

[0048] Clear channel assessment thresholds and transmit power control (CCA / TPC) based on BSS color can be provided. Figure 5 shows an example of clear channel assessment (CCA) thresholds by basic service set (BSS) color. As shown in Figure 5, the CCA threshold criteria and / or transmit power of STA1 in BSS1 can be modified based on, for example, a source BSS decision (e.g., initial decision) on the overheard transmission, or the impact of the overheard transmission by STA1 on STA2 in BSS2 that is the receiver of the overheard transmission.

[0049] An initial determination of the source BSS of an overheard transmission can be identified in a downlink transmission using a BSS color parameter located in the preamble. If the BSS color of the transmission is not equal to that of the STA, the transmission can be deemed not to be from its own BSS (e.g., the transmission may be an OBS transmission). If the BSS color of the transmission is equal to that of the STA, the transmission can be deemed to be from its own BSS.

[0050] An initial determination of the source BSS for an overheard transmission can be identified in an uplink transmission, for example, using the receiving address (RA) of the overheard packet. If the RA is not equal to the address of its AP, the transmission can be from its own BSS. If the RA is equal to the address of its AP, the transmission can be from its own BSS. The receiving address can be a compressed version of the RA, such as a partial AID. As shown in FIG. 5, a transmission from STA2 or AP2 can be identified as an OBSS transmission by STA1, for example, if the colors of BSS1 (e.g., operated by AP1) and BSS2 (e.g., operated by AP2) are different.

[0051] 5, the CCA threshold criteria and / or transmit power of STA1 in BSS1 can be modified based on the impact of a transmission by an overhearing STA, e.g., STA1, on a recipient of the overheard transmission, e.g., STA2. The overhearing STA, e.g., STA1, can identify the receiver characteristics of the recipient of the overheard transmission, e.g., STA2.

[0052] For example, as shown in FIG. 5, STA1 can identify receiver characteristics (e.g., required Rx sensitivity or Rx power) associated with a receiving OBSS STA, e.g., STA2, and / or modify its own CCA threshold in an STA-specific manner. Knowledge of its own receiver and / or the receiver requirements of the receiver of the OBSS transmission allows it to set its CCA threshold (e.g., transmit power) to a level that can be beneficial to both STAs. A discovery mechanism can be utilized to identify the receiver requirements and / or characteristics for the receiving OBSS STA, STA2. The discovery mechanism can be utilized to identify the receiver requirements and / or characteristics for one or more (e.g., all) OBSS STAs. The identified receiver requirements and / or characteristics can be stored, for example, for use at an appropriate time.

[0053] For example, STA1 may identify one or more STAs that may have receiver requirements below or within a threshold. STA1 may modify its CCA associated with the receivers in the group in a common manner.

[0054] The receiver requirements can be collected explicitly or implicitly. For example, a network may include an AP, a STA (e.g., STA2) in an OBSS, and a STA (e.g., STA1) in a BSS managed by the AP. The STA (e.g., STA2) may broadcast (e.g., periodically broadcast) a packet with its transmit power and / or its minimum receive power and / or headroom for a desired operating point (e.g., MCS and SNR). The desired operating point may be derived and / or determined, for example, by the AP or sender, from the STA's received ACK / NAK statistics. The desired operating point may be specified in advance. The STA (e.g., STA1) receiving this packet may estimate (e.g., implicitly estimate) the impact of their transmission on the receiver of the OBSS STA (e.g., STA2).

[0055] For example, a frame exchange can occur between two STAs (e.g., STA1 and STA2) with a request (e.g., an explicit request) from STA1 to STA2 for its receive power requirements. STA2 can send a frame indicating its transmit power and / or minimum receive power for a desired operating point (e.g., MCS or SNR). Other STAs can overhear this transmission and utilize the information as described herein. Inter-BSS requests can be enabled. For example, STA1 can estimate (e.g., implicitly estimate) STA2's receiver power requirements by measuring the power received when STA2 is transmitting. STA1 can know STA2's transmit power and desired operating point explicitly or implicitly.

[0056] CCA based on transmitter and / or receiver characteristics (e.g., BSS color and / or Rx sensitivity) can be effected. The CCA threshold criteria used by a STA (e.g., STA1) can be modified based on whether the transmission overheard by the STA is within its own BSS or from an OBSS, e.g., using the BSS color / RA, and / or the Rx sensitivity of the receiver of the OBSS transmission. Based on this information, exemplary CCA thresholds can be estimated as described herein. CCA threshold estimation, as variously described herein, can include setting and / or using an estimated CCA threshold. The STA (e.g., STA1) can overhear the packet transmission and / or decode the SIG field. If the transmission is from a node within the STA's own BSS, the transmission is protected (e.g., always protected), leading to the following: CCA = -inf (e.g., or minimum acceptable value)

[0057] If the transmission is from a node within the OBSS, the transmission can be protected based on estimating the new CCA threshold. If the energy in the channel exceeds the new CCA threshold, the transmission can be protected. If the energy in the channel is below the new CCA threshold, the STA is free to transmit. The CCA threshold can be estimated as follows: CCA(dBm)=CCA_nominal(dBm)+Margin(dB) Margin=f(AP_STA1,STA2_STA1) The function using which the margin is determined can include information from the STAs, such as one or more of their receiver sensitivity, transmit power level, transmit headroom, capabilities, etc. One or more of CCA_nominal, margin, AP_STA1, or STA2_STA1 can be assumed. CCA_nominal can refer to the baseline CCA for the network and / or the BSS-specific CCA used in the network. The margin can refer to a STA-specific modification of the nominal CCA. The margin can be a function of the transmission in the STA's own BSS, e.g., BSS1, between a STA in its own BSS, e.g., STA1, and an AP in its own BSS, e.g., AP1, and / or the receiver requirements of an OBSS STA, e.g., STA2, receiving (e.g., currently receiving) packets from its AP in an OBSS, e.g., BSS2, from STA1's perspective. If the margin for some or all STAs is zero, the CCA adjustment can be BSS-wide. AP_STA1 used in calculating Margin can refer to the receiver requirements of the AP, for example, based on transmissions from STA1 to AP1 within BSS1. For example, it can be a function of the channel gain between AP1 and STA1, estimated by the SINR of the transmission at the AP or the power received at the AP due to a transmission by STA1 (e.g., or vice versa). A STA with a higher channel gain or higher SINR / received power can transmit at a higher rate and / or with less interference to out-of-BSS transmissions and can have a higher CCA, and / or vice versa.

[0058] STA2_STA1 used in calculating Margin can refer to the receiver requirements of STA2, e.g., based on transmissions from STA1 to AP1. For example, it can be a function of the channel gain between STA2 and STA1, as estimated by the power received at STA2 due to transmissions by STA1 (e.g., or vice versa). STAs with higher channel gain or higher SINR / received power can transmit at higher speeds and with less interference to out-of-BSS transmissions, and can have higher CCA, and / or vice versa.

[0059] for example,

[0060]

number

[0061] where CCA_bias is equal to the range over which CCA can be varied in the network, Gain_min may be the channel gain associated with the desired worst channel, and Gain_max may be the channel gain associated with the desired best channel.

[0062] To estimate the channel gain, one or more of the following mechanisms may be utilized: To estimate the channel gain, the AP may send out a broadcast frame with information about its transmit power within the frame; One or more (e.g., each) STA may use the transmit power information and / or the received power to estimate the channel gain from the AP; The AP may poll one or more (e.g., each) STA, and one or more (e.g., each) STA may feed back the estimated channel gain; One or more (e.g., each) STA may send back (e.g., piggyback) information about the channel gain on any frame it sends to the AP; The AP may poll STAs that may not have sent back information within a certain duration.

[0063] To estimate the channel gain, the AP can send a frame requesting the STA to include its transmit power in any packet (e.g., any packet) that the STA may send. The AP can poll one or more STAs (e.g., each STA) to send a null data packet (NDP) with transmit power information piggybacked on the frame. The AP can use this information to estimate the channel gain for a particular STA (e.g., assuming channel reciprocity).

[0064] A CCA threshold estimation can be performed. For example, a CCA criterion can be selected based on one or more of the following: STA1 can overhear a packet transmission and / or decode a SIG. If STA1 determines that the received packet transmission belongs to its own BSS transmission, the transmission can be protected (e.g., always protected). CCA can be equal to -inf (e.g., or a minimum value in a tolerance range). If STA1 determines that the received packet transmission does not belong to its own BSS transmission, the transmission can be protected, for example, based on estimating a new CCA threshold. If the energy in the channel exceeds the CCA threshold, the transmission can be protected. If the energy in the channel is below the CCA threshold, the STA is free to transmit. In this case, the estimated CCA threshold can depend on whether an OBSS transmission is detected. In this case, the CCA threshold in an OBSS scenario can differ from the CCA threshold in a non-OBSS scenario. The CCA threshold can be estimated as follows: CCA(dBm)=CCA_nominal(dBm)-Margin(dB)

[0065] If the received transmission is an OBSS transmission, the margin may be set to:

[0066]

number

[0067] If no transmission is received and / or if a transmission is received from an unidentified BSS, the margin may be set to:

[0068]

number

[0069] Rather than making the CCA specific to a STA, the CCA thresholds can be grouped, for example, based on channel gain. For example, STAs within a certain gain range can have their margin set to the same value. This can be a margin associated with a particular gain value within the range, such as the maximum gain, minimum gain, or average gain (e.g., mean or median gain), such as having the same margin. When STAs are grouped together based on criteria, such as in MU-MIMO, the CCA can be associated with a group ID, and STAs belonging to a particular group can be assigned the CCA threshold for that group ID.

[0070] TPC based on BSS color can be provided. The CCA threshold criteria and transmit power used by a STA (e.g., STA1) can be changed based on, for example, whether the transmission overheard by the STA is within its own BSS or from an OBSS, e.g., using the BSS color, and / or the Rx sensitivity of the receiver of the OBSS transmission.

[0071] The CCA criteria and transmit power can be set as described herein. A STA (e.g., STA1) can overhear a packet transmission and / or decode the SIG field. If the transmission is from a node within the STA's own BSS, the transmission can be protected (e.g., always protected). In such a case, the transmission cannot be present. CCA can be equal to -inf (e.g., or the minimum value of the tolerance range). The transmit power for a transmitting STA can be set as a function of the gain between the STA and the AP. Tx_power=nominal_Tx_power-(Rx_power_AP1-Rx_power_desired_AP1) If the transmission is from a node within the OBSS, the CCA threshold criterion and transmit power can be estimated as follows: CCA=CCA_nominal+Margin Tx_power=Tx_power_nominal-Margin Margin=f(AP_STA1,STA2_STA1) In this case, the STA transmit power can be a function of its receiver and the receiver of the out-of-BSS transmission. AP_STA1 can refer to the receiver requirements of the AP, for example, based on transmissions from STA1 to AP1. For example, this can be a function of the channel gain between AP1 and STA1, estimated by the signal-to-interference-and-noise ratio of the transmissions at AP1, or the power received at AP1 due to transmissions by STA1 (e.g., or vice versa). A STA with a higher channel gain or higher SINR / received power can transmit at a higher rate and with less interference to out-of-BSS transmissions, and can have a higher CCA, and / or vice versa. STA2_STA1 can refer to the receiver requirements of STA2, for example, based on transmissions from STA1 to AP1. For example, this can be a function of the channel gain between STA2 and STA1, estimated by the power received at STA2 due to transmissions by STA1 (e.g., or vice versa). STAs with higher channel gain or higher SINR / received power can transmit at higher rates and with less interference to out-of-BSS transmissions, have higher CCA, and / or vice versa. For example,

[0072]

number

[0073] where CCA_bias is equal to the range over which CCA is varied in the network, Gain_min may be equal to the channel gain associated with the desired worst channel, and Gain_max may be equal to the channel gain associated with the desired best channel.

[0074]

number

[0075] For example, a channel gain can be associated with a group ID, and STAs belonging to a particular group can be assigned a particular channel gain.

[0076] Advanced spatial reuse can be achieved using BSS colors. Figure 6 shows an example of overlapping OFDM transmissions of intended signals in the presence of strong interference. As shown in Figure 6, a STA (e.g., a receiving STA) may encounter strong interference within the same or overlapping frequency band, e.g., due to parallel OFDM transmissions. For example, such a scenario may occur when one or more BSSs are densely deployed. For example, due to a lack of coordination between one or more WiFi APs and / or one or more STAs, neighboring APs or STAs in an OBSS may transmit their signals using overlapping carrier frequencies and subcarrier structures relative to those used by APs in their own BSS. In a densely deployed WLAN system, interference induced by APs and / or STAs in an OBSS can be extremely challenging. Direct interference suppression mechanisms, such as spatial domain suppression or frequency domain suppression, may work poorly in such densely deployed scenarios, e.g., due to low signal-to-interference ratios at the STAs.

[0077] Systems, methods, and means for signaling between a transmitter and a receiver to enable multiple OBSS transmissions can be provided. A STA at the edge of a coverage area can check the BSS color information in the preamble of a received signal of interest, for example, if the STA detects an unknown interfering signal within the same frequency band as that used for CCA. The STA can determine the channel characteristics of the interfering channel if, for example, the BSS color indicates that the signal is from an OBSS. Mechanisms used by the STA can utilize sounding the interfering channel, enhancing channel estimation of the interfering channel using known signal components of the interfering channel (e.g., the preamble of the transmitted frame), and / or using a side channel, such as the primary channel, to determine potential resource loading of adjacent channels.

[0078] The STAs and / or APs can perform intelligent resource allocation and / or interference suppression, e.g., when interference is identified, to limit the effects of interference and / or to allow STAs in overlapping BSSs to transmit / receive data, e.g., with minimal interference.

[0079] A channel may have resources in time, frequency, space, and / or beams. Channel resource allocation may use one or more of these resources to improve interaction between nodes that may transmit simultaneously in overlapping BSSs. For example, if interference is suspected in one resource, an alternative resource may be used. A channel may support multiple subchannels that may be orthogonal in frequency. A channel may support different time slots, allowing for multiple resource opportunities. If interference is suspected in one subchannel (e.g., based on information gathered from the BSS color of the preamble), another subchannel may be selected for transmission.

[0080] A channel can support downward-tilted and / or upward-tilted beams, which, when used in combination, can be equivalent to an omnidirectional beam in the vertical. If interference is suspected, the energy in the upward-tilted and downward-tilted beams can be compared to determine the severity of the interference and identify channel resources that may be more favorable for communication. This mechanism can be extended to two or more beams for a channel resource. Some channel beams (e.g., downward-tilted beams) may not experience interference from an OBSS, while other beams (e.g., upward-tilted beams) may experience such OBSS interference.

[0081] The channel may support transmit or receive beamforming, for example, to enable interference suppression if interference is suspected. Signaling may be provided to assist resource allocation. Signaling associated with beamforming may be provided.

[0082] Signaling and beamforming can be effected at the AP in the STA's own BSS. Figure 7 shows the MAC frame format of a feedback packet from a STA to an AP in the STA's own BSS. STAs that support beamforming in their own BSS can feed back channel state information (CSI) of the interfering channel to the AP in their own BSS. The AP can use beamforming to avoid receiving interference at the STA. TPC, CCA, and / or interfered channel ID can be sent to the AP in their own BSS. Messages sent by a STA to its AP in its own BSS can be used by the AP to minimize the impact on parallel transmissions in the BSS. These messages can be used for interference cancellation, for example, when spatially orthogonal transmission is used.

[0083] A STA within its own BSS may cause severe interference to ongoing transmissions at neighboring devices in the OBSS, for example, if parallel feedback is provided over the same frequency band used in the OBSS. Frequency, time, and / or spatial separation of feedback signals can be employed. This can be done to minimize the impact on communications within the OBSS.

[0084] Signaling using non-overlapping frequency subbands can be provided. Figure 8 shows feedback information to an AP in a STA's own BSS using non-overlapping secondary channels. As shown in Figure 8, partial overlap of frequency bands between a STA's own BSS and an OBSS can be utilized. For example, in the case of transmission using a 40 MHz bandwidth as shown in Figure 8, a STA in its own BSS can select to use the primary 20 MHz channel occupied by the OBSS to achieve and / or enable spatial reuse. A STA in its own BSS can select a secondary 20 MHz channel different from that used in the OBSS. The non-overlapping channel can serve as a feedback channel to send information to an AP in the STA's own BSS to be utilized for simultaneous transmission on the overlapping primary channel. Information acquisition and feedback can be provided as described herein. CCA performed at the STA can indicate that the 20 MHz primary channel may be occupied.

[0085] The STA may choose to decode the SIG field, for example, to check the BSS color. The BSS color may indicate that transmissions may be in adjacent OBSSs. The STA may continue CCA on other channels and may determine an idle channel. The STA may determine to use a 20 MHz primary channel and an idle 20 MHz channel. The idle 20 MHz channel may be different from the secondary channel used in the OBSS for simultaneous transmissions. The STA may estimate the interfering channel, for example, based on a received interfering signal. The STA may send the channel ID, CCA, TPC, interfering channel CSI, and / or other information of the primary and secondary channels to an AP in the STA's own BSS. The STA may send the information through a non-overlapping secondary channel. The AP in the STA's own BSS may use the feedback information to select an appropriate transmit power. The transmit power may be such that it may not lead to interference (e.g., significant interference) in adjacent OBSSs. Simultaneous transmissions may proceed on the interfered primary channel and the uninterfered secondary channel.

[0086] Signaling using spatially orthogonal transmission can be provided. Spatial orthogonal transmission can be used by a STA to feed back information to its own AP. For example, a STA with strong spatial domain processing capabilities can use such spatially orthogonal transmission. A STA in its own BSS can have multiple antennas. The multiple antennas can be used to create spatial nulls. The spatial size occupied by an interfering signal from an OBSS may not be excessive. In the case of a large interfering signal, a STA in its own BSS may not be able to process the spatially orthogonal transmission.

[0087] There may be several application examples for signaling using spatial orthogonal transmission. For example, one or more (e.g., all) legacy devices in an adjacent OBSS may transmit (e.g., always transmit) in single-input single-output (SISO) mode. A STA in its own BSS (e.g., primary BSS) may have a sufficient number of antennas, which may be greater than the number of ongoing transmission streams in the OBSS. In an example, there may be two transmissions in the OBSS, and only one OBSS may be active. In this case, a STA in its own BSS may have three or more antennas to enable cancellation of two streams of interference from the OBSS. In an example, devices in an adjacent OBSS may use MIMO transmission. Because there may be several STAs in the OBSS that may simultaneously transmit to their associated AP, the overall spatial magnitude of the interfering signal may be large. A STA in its own BSS may not have the number of antennas that may be required for spatial nulling (e.g., spatial nulling only). When an adjacent AP transmits, associated STAs in the OBSS may be assumed to be muted. A STA within its own BSS may choose to feedback (e.g., only feedback) information during the transmission of a neighboring AP, in which case the STA may need to have a greater number of antennas than that of the neighboring AP.

[0088] FIG. 9 illustrates spatial orthogonal feedback. As shown in FIG. 9, at 902, the CCA process in a STA within its own BSS may indicate that the scanned channel is occupied. At 904, the STA may decode the SIG field and check the BSS color. The BSS color may indicate that the transmission may be from an adjacent OBSS. The STA may estimate channel state information (CSI) of the interfering channel, for example, using a long training field (LTF) in the received interfering signal. At 906, the STA may determine transmission parameters, such as space-time block coding (STBC), number of space-time streams (NSTS), and / or beamforming information from the SIG field. This information may be used to determine whether devices within the OBSS use MIMO. For example, if NSTS>1 and STBC=1, a MIMO configuration may be indicated. In another example, if NSTS=1 and STBC=0, the beamforming bit may be checked. If the beamforming bit is 1, MIMO may be used. Other combinations of STBC, NSTS, and beamforming bits can indicate SISO mode. At 910, if MIMO mode is used in the adjacent OBSS, the STA in its own BSS can check the group ID in the SIG field to identify whether the transmission originates from an adjacent OBSS AP. The STA can calculate a beamforming vector in the null space of the signal space occupied by the transmission of the adjacent OBSS AP. At 914, the STA in its own BSS can send feedback information to the AP in its own BSS using the calculated beamforming vector. The STA in its own BSS can send feedback information simultaneously when the adjacent OBSS AP transmits. At 908, if SISO is used in the adjacent OBSS, the STA in its own BSS can calculate a beamforming vector in the null space of some or all interfering signals from APs and / or STAs in the adjacent OBSS.At 912, a STA in its own BSS may send feedback information to an AP in its own BSS using the beamforming vector. The STA in its own BSS may send feedback information simultaneously while the APs and / or STAs in neighboring BSSs are communicating.

[0089] An example receiver for receiving simultaneous transmissions with strong OBSS interference is described herein. FIG. 10 shows demodulated interfering symbols, with the intended symbols mixed in as noise. During reception, the STA may attempt to demodulate the interfering signal in error, e.g., due to the signal of interest being suppressed by the interference. As shown in FIG. 10, the interfering signal may have high received power at the STA and may use high QAM modulation (e.g., 16QAM). The intended signal sent by an AP in the STA's own BSS may have relatively low received power and may use QPSK modulation.

[0090] After removing the cyclic prefix (CP) and transforming the signal into the frequency domain using FFT, the received signal on the kth subcarrier is Y k =H 1,k X 1,k +H 2,k X 2,k +N k where H 1,k may be the desired channel response between the STA and the associated AP, and X 1,k Let be the intended symbol on the kth subcarrier, and H 2,k can be the interference channel response, and X 2,k may be the interfering symbol on the k-th subcarrier.

[0091] Received signal Y k is the estimated interference channel on the k-th subcarrier

[0092]

number

[0093] The demodulated interference symbols can be equalized using

[0094]

number

[0095] can be obtained along with the intended signal as a fraction of the effective noise. As shown in Figure 10, the interfering symbol constellations are represented as small dots. Larger dots with crosses through them indicate the transmitted constellations of the interfering symbols. The symbol error rate (SER) of the demodulated interfering symbols can be high due to, for example, noise from the intended signal.

[0096] The interfering signal can be encoded by a strong error correcting code, such as an LDPC or a binary convolutional code (BCC). The STA can demap the interfering symbols and decode the bit sequence. Thanks to the LDPC or BCC, the coded bit error rate of the interfering signal can be low (e.g., fairly low). The STA can use modulation and coding scheme (MCS) information obtained from the interfering packet preamble to encode and / or modulate the corrected bit sequence of the interferer. The STA can have a lower (e.g., much lower) SER and can easily estimate the interfering symbol.

[0097]

number

[0098] can be extracted.

[0099] STA receives signal Y k From this, the estimated strong interference

[0100]

number

[0101] The STA can use the CSI between itself and the AP in its own BSS obtained in the non-interfering transmission phase. The STA can demodulate and / or decode the intended signal without strong interference.

[0102] To remove OBSS interference, an interference suppression receiver, such as an interference rejection receiver, can be used, rather than using an interference cancellation receiver. The OBSS transmission can begin, for example, before the STA's own BSS transmission, which can enable the STA to estimate the channel and / or decode the SIG field and identify the color. The packet for the STA's own BSS transmission can finish after the transmission for the OBSS transmission. In this case, the transmission of an ACK from STA1 to the AP in the STA's own BSS can occur normally. In an example, the STA's packet for its own BSS transmission can finish before the transmission from the OBSS transmission, for example. Returning an ACK for successful decoding may result in interference at STA2. In this case, a beamformer can be used to direct transmissions to AP1. A deferred ACK can be used to send an acknowledgment to the transmitter. For example, STA1 and AP1 can negotiate and agree on a maximum deferral time (e.g., a maximum number of transmissions) within which the STA can send an ACK. If the AP and STA agree on the possibility of a deferred ACK, the AP can complete transmission and send a deferred ACK request. This can allow the rest of the network to resume transmission. The STA can send a deferred ACK. For example, the STA can send a deferred ACK at its convenience.

[0103] FIG. 11 illustrates interference cancellation and deferred ACK in an exemplary WLAN. Interference cancellation can be achieved using BSS color. As shown in FIG. 11, AP2 in BSS2 can send a capability request 1102 for deferred ACK capability to STA2 in BSS2. Information in the capability request can include a maximum deferral time or a maximum number of other STA transmissions that can occur before the AP can determine that a transmission has failed. Information in the request can include, for example, a duration within which a successful ACK can be sent in the absence of deferrals. The STA can send an ACK SIFS-x×slot_time after transmitting data. This may be to allow the AP to send a deferred ACK frame SIFS after sending its data, for example, to allow transmission within the BSS to resume.

[0104] STA2 can send a capability response indicating that it may have deferred ACK capability. STA2 can respond with different deferred ACK parameters. STA2 may experience interference 1104 (e.g., heavy interference) (e.g., as an edge STA) and decide to enter deferred ACK mode. STA2 can send a deferred ACK mode request to AP2. AP2 can send a deferred ACK mode response to STA2 indicating that transmissions with this STA may be in deferred ACK mode from now on. This may include parameters such as parameter x, which indicates the time AP2 can expect an ACK from STA2 if the transmission is successful.

[0105] As shown in Figure 11, STA1 can send information 1106 to AP1 in BSS1. This can cause interference 1104 (e.g., strong interference) to STA2. STA1 can send information (e.g., receiver address in addition to BSS color) to enable STA2 to identify out-of-BSS transmissions. AP2 can send frames to STA2, for example, during the time that STA1 can send information to AP1. The interference 1104 (e.g., strong interference) can be canceled, for example, as discussed herein.

[0106] 12 shows an example of a deferred ACK operation. In acknowledgment of successful reception of a transmission, one or more of the following may occur: As shown in FIG. 12, AP2 may send information to STA2, e.g., with a transmission duration shorter than the duration of the transmission between STA1 and AP1. STA2 may send an ACK SIFS duration after the end of the transmission. The ACK sent by STA2 may not affect data reception at AP1 or potentially affect ACK reception at STA1.

[0107] AP2 and STA2 can implement a deferred ACK, for example, to avoid interference with the primary transmission from STA1 to AP1. AP2 can wait for a SIFS duration after its transmission and not receive an ACK. AP2 can send an ACK deferred frame to allow nodes in BSS2 to resume transmission. After completing its transmission from STA1 to AP1, STA2 can contend for the channel medium and send a deferred ACK to AP2. This frame can be piggybacked on a data transmission. The deferred ACK from STA2 to AP2 can be transmitted within a maximum deferral time. If the maximum deferral time expires, AP2 can assume the transmission failed and retransmit the information to STA2.

[0108] In acknowledgment of successful reception of a transmission, one or more of the following may occur: Figure 13 shows an example of an ACK operation. As shown in Figure 13, STA1 may send information to AP1 with a transmission duration that exceeds the transmission duration between AP2 and STA2. STA2 may wait SIFS-x x slot_time after completing data transmission. STA2 may send an ACK to AP2.

[0109] STA2 may move to an environment where interference (e.g., heavy interference) may not be a problem. STA2 may send a deferred ACK mode stop request to AP2. AP2 may send a deferred ACK mode stop response to STA2 indicating that deferred ACK mode may be stopped going forward.

[0110] Transmission scheme-specific BSS colors can be provided. BSS colors can be extended to include information about the specific techniques that may be used for transmission. The extended BSS colors can allow STAs in neighboring BSSs to identify that a transmission may be from another BSS. The extended BSS colors allow STAs in neighboring BSSs to identify the characteristics of the specific scheme used to transmit in the neighboring BSS and modify their behavior accordingly.

[0111] An example of a transmission scheme-specific BSS color can enable STAs in neighboring BSSs to adapt to transmissions in the OBSS. As described herein, a scheme can include OBSS information and / or scheme-specific information. Examples that can benefit from including both OBSS information and scheme-specific information include one or more of downlink (DL) OFDMA, uplink (UL) OFDMA, OFDM, BSS silencing, interference avoidance with sectorized transmissions, and / or DL / UL OFDMA with peer-to-peer (P2P) transmissions.

[0112] In DL OFDMA, OFDMA can be used with one or more of the bands as empty bands, or the AP can transmit to STAs in the cell center. In DL OFDMA, one or more STAs in neighboring BSSs can use additional color information to identify where and when STAs in neighboring BSSs can transmit with minimal interference to OFDMA transmissions. For OFDMA transmissions, subbands can be small portions of a 20 MHz band (e.g., for sub-channelized OFDMA transmissions), or they can be the full 20 MHz band (e.g., for channel-based OFDMA transmissions).

[0113] In UL OFDMA, STAs in neighboring BSSs can use additional color information to identify where and when they can transmit with minimal interference due to spatial reuse of bands. In UL OFDMA, OFDMA can be used for uplink transmissions in neighboring BSSs (e.g., as opposed to OFDM, which occupies the entire bandwidth). In UL OFDMA, one band can have STAs close to the AP. For OFDMA transmissions, subbands can be small portions of a 20 MHz band (e.g., for sub-channelized OFDMA transmissions), or they can be the full 20 MHz band (e.g., for channel-based OFDMA transmissions).

[0114] In OFDM, if OFDM can be used in neighboring BSSs, the BSS can indicate when STAs that are robust to BSS interference can transmit and / or receive information. Neighboring STAs can use this information when transmitting.

[0115] In BSS silencing, in a dense network with BSS transmissions, a BSS can indicate its BSS color and its intention to remain silent at a desired time and for a desired duration. Neighboring BSSs can use this information to decide when to transmit (e.g., to transmit during a quiet period), which can improve network performance.

[0116] In interference avoidance through sectorized transmissions, in dense networks, a BSS can indicate its color, the sectors to which DL transmissions can be directed, and the duration of the transmission. Neighboring BSSs can use this information to improve network performance. For example, an OBSS can identify a specific orthogonal beam to use when a transmission with a particular enhanced color can be detected.

[0117] In DL / UL OFDMA with peer-to-peer (P2P) transmission, when OFDMA is used with one or more of the bands empty or silenced, P2P STAs within the same BSS can use additional color information to identify where and when they can transmit with minimal interference to the OFDMA transmission.

[0118] The BSS information and / or scheme-specific information can be transmitted in the SIG field of the transmitted frame. The information that can be transmitted can include an uplink indication bit, a transmitting node / BSS identification, scheme identification information, and / or scheme-specific information.

[0119] An uplink indication bit can be transmitted to indicate whether the transmission is an uplink or downlink transmission. A transmitting node / BSS identification can be transmitted. For example, for a downlink transmission (e.g., the uplink indication bit is set to 0), the transmitting node / BSS identification can be the BSS color and MAC address or partial AID of the BSS. The BSS color can be used to identify the transmission associated with the STA's own BSS or OBSS. For an uplink transmission (e.g., the uplink indication bit is set to 1), the transmitting node / BSS identification can be the MAC address or partial AID of the transmitting node. In this case, the MAC address or partial AID stored in the receiving address can allow the STA to identify the transmission associated with its BSS and / or OBSS. The BSS color can be transmitted in both uplink and downlink transmissions.

[0120] Scheme identification information can be transmitted (e.g., the information can be conveyed by a combination of bits). The scheme used can be transmitted in the SIG. For example, a 3-bit field can be used in combination with the uplink indication bits to identify the specific scheme used. For example, 000 can indicate OFDM (default), 001 can indicate OFDMA, 010 can indicate BSS silencing, 011 can indicate interference avoidance with sectorized transmission, 100 can indicate OFDMA with band silencing, and 101, 110, and 111 can be reserved. A direction bit can be combined with the scheme bit to identify whether UL / DL OFDMA, UL / DL OFDM is used.

[0121] Scheme-specific information can be transmitted (e.g., the information can be conveyed by a bit combination). This can be used to identify the information used for the scheme. For example, a 4-bit field can be used along with the scheme identification information to communicate information about that particular scheme. For example, the same field can mean different things depending on the specific scheme used. For example, using the format {Direction Bits}{Scheme}{Information}, {DL}{OFDMA}{1101} can indicate uplink OFDMA with four subbands, where subband 3 is available for OBSS transmission by STAs that may be robust to interference. {DL}{Silencing}{1000} can indicate downlink silencing with sector 0 active.

[0122] For UL / DL OFDMA, bands that can be used by neighboring BSSs during transmission can be identified. Examples include identifying bands that can be utilized for transmission to BSS-centric STAs in neighboring BSSs as reception at the AP (e.g., in UL transmissions) or at the STAs (e.g., in DL transmissions). Such bands can be more robust to interference.

[0123] For UL / DL OFDMA, bands that cannot be used by neighboring BSSs during transmission can be identified. Examples include bands that can be utilized for transmission to BSS edge STAs in neighboring BSSs, either as reception at the AP (e.g., in UL transmission) or at the STA (e.g., in DL transmission). Such bands may be less robust to interference.

[0124] For OFDM, when a STA that is robust to the transmission is transmitting or receiving can be identified. Neighboring STAs can use this information when transmitting. In BSS silencing, the start and duration of the quiet period can be identified. For interference avoidance in sectorized transmissions, the start and duration of the transmission can be identified. For example, the active sectors in an OBSS and the active sector direction can be identified. Sectors that cannot be used by any OBSS transmission can be identified. For CCA threshold information, the enhanced color information can include the desired Rx sensitivity / threshold, such as those described herein.

[0125] UL / DL OFDMA transmissions using enhanced BSS colors can be achieved. Figure 14 shows an example of a UL / DL OFDMA WLAN system. Figure 15 shows an example of UL / DL OFDMA packet exchange type 1. Figure 16 shows an example of UL / DL OFDMA packet exchange type 2. Figure 17 shows an example of UL / DL OFDMA packet exchange type 3. The examples described herein can be used in downlink OFDMA. For example, a DL OFDMA transmission can have four subbands. As shown in Figures 14, 15, 16, and 17, AP2 in BSS2 can initiate a downlink OFDMA transmission. AP2 in BSS2 can indicate in the SIG field that the subchannels occupied by STA4 and STA5 may be robust to BSS interference, for example, due to their proximity to the AP. STA1 in BSS1 can overhear the BSS2 transmission and schedule its transmission in either or both subchannels.

[0126] As shown in Figures 14, 15, 16, and 17, AP2 in BSS2 can send information to STAs in that BSS using OFDMA. For example, BSS2 can initiate downlink OFDMA transmissions with STA2 (e.g., using channel 1), STA3 (e.g., using channel 2), STA4 (e.g., using channel 3), and STA5 (e.g., using channel 4) by sending an OFDMA schedule frame to some or all of the STAs. Each of the STAs can reply with an OFDMA response frame. The AP can transmit information to the STAs. STAs that successfully receive the transmission can reply with an acknowledgement (ACK).

[0127] The enhanced BSS color information can be transmitted in the SIG field of one or more (e.g., all) of the following frames: The enhanced color information can indicate that one or more channels (e.g., channel 3 and / or channel 4) are available for transmission (e.g., by transmitting {1100}). The OFDMA / COBRA channel can reserve or schedule an OFDMA / COBRA frame to reserve channel resources for OFDMA / COBRA transmission and / or indicate the subchannels used by one or more STAs (e.g., STA2, STA3, STA4, and STA5). One or more OFDMA / COBRA response frames from one or more (e.g., each) of the STAs (e.g., STA2, STA3, STA4, and STA5) can be used to acknowledge (schACK) the receipt of the schedule frame. One or more (e.g., each) of the STAs can send the entire enhanced color information to inform nearby BSS STAs about the STA. One or more (e.g., each) of the STAs may send (e.g., only send) basic BSS color information, information about the particular scheme, and / or information about the subchannels to which it has been assigned (e.g., only assigned) to the STA.

[0128] As shown in FIG. 15, in a Type I packet exchange, color information can be sent on one or more (e.g., each) of the subbands. As shown in FIG. 16, in a Type II packet exchange, color information can be sent across the channel bandwidth (e.g., the entire channel bandwidth). As shown in FIG. 17, in a Type III packet exchange, color information can be sent across the bandwidth (e.g., the entire bandwidth) and can be time-delayed, for example, to avoid overlap. As shown in FIG. 17, schACK frames associated with each of the STAs can be sent simultaneously on their respective subbands. One or more of the schACK frames can be preceded by a blank transmission or dummy information 1702. This dummy information 1702 can be skipped by the receiver, for example, based on the STA's position in the OFDMA scheduling group. An OFDMA data frame can be sent from the AP to one or more STAs (e.g., each of STA2, STA3, STA4, and STA5). An ACK frame can be sent from one or more STAs (e.g., each of STA2, STA3, STA4, and STA5). The enhanced color information transmitted can be similar to that transmitted in the schACK. The enhanced color information can be the same and / or can be transmitted in one or more (e.g., all) of the frames in an OFDMA transmission frame exchange.

[0129] As shown in Figures 15, 16, and / or 17, for example, STA1 in BSS1 can overhear a transmission from BSS2, for example, from AP2 or STA2 in BSS2. For example, in a high-density environment, STA1 can overhear a COBRA schedule frame from AP2. For example, the received frame can be received with a power greater than STA1's receiver sensitivity. STA1 can hear a schACK frame from STA2.

[0130] STA1 can decode the preamble of the received transmission from BSS2. For example, the preamble can include an updated SIG field with enhanced BSS color information. STA1 can resume CSMA / CA channel access on one or more channels (e.g., channel 3 and channel 4). STA1 can send information to AP1 on any of the channels (e.g., channel 3 as shown in Figures 15, 16, and 17).

[0131] STA1 in BSS1 can indicate to AP1 in BSS1 the identity of channels STA1 can use and / or channels STA1 cannot use. For example, STA1 can communicate such an indication in response to a downlink OFDMA / COBRA channel request (e.g., from AP1 in BSS1). STA1 can indicate that it can use one or more channels (e.g., channel 3 or channel 4 only) and / or that it cannot use one or more channels (e.g., channel 1 or 2). STA1 can send an uplink OFDMA / COBRA data request (e.g., to AP1) with information that it can use channel 3 or channel 4 (e.g., channel 3 or channel 4 only) and / or that it cannot use channel 1 or 2. STA1 can send the information to an AP in STA1's BSS (e.g., AP1 in BSS1) with minimal impact to APs in the BSS (e.g., AP2 in BSS2).

[0132] Uplink COBRA / OFDMA transmission can be similar to downlink OFDMA as described herein. For example, a STA can send a request to the AP to be scheduled based on the data in its buffer. The STA can receive an OFDMA scheduling frame from the AP to transmit in a specific band. The STA can send a schACK with enhanced color information to the AP. The STA can send data with enhanced color information to the AP.

[0133] UL / DL OFDM transmission with enhanced BSS color can be provided. FIG. 18 shows an example of UL / DL OFDM transmission with enhanced BSS color. FIG. 19 shows an example of UL / DL OFDM packet exchange. As shown in FIGS. 18 and 19, AP1 in BSS1 can communicate with (e.g., send transmissions to) STA1 and / or STA2. Even though the CCA threshold and BSS color may be identical for both transmissions, the use of enhanced BSS color allows STA3 in BSS2 to transmit, for example, when the receiver of the primary transmission may be robust to interference.

[0134] As shown in Figures 18 and 19, AP1 in BSS1 may send an OFDM transmission to STA1. STA1 in BSS1 may not be robust to OBSS interference from STA3 in OBSS BSS2. AP1 may send enhanced color information in the preamble of its transmission, for example, indicating that it may use OFDM transmission and that the channel cannot be used. STA3 in OBSS BSS2 may overhear the transmission from BSS1 and the enhanced color information. STA3 may set its channel to busy and cannot transmit.

[0135] AP1 in BSS1 can send an OFDM transmission to STA2, for example, at another time. STA2 can be robust to OBSS interference from STA3 in OBSS BSS2. AP1 can send enhanced color information in the preamble of its transmission to indicate that it uses OFDM transmission and / or which channel can be used (e.g., in parallel). STA3 in OBSS BSS2 can overhear the transmission from BSS1 and / or the enhanced color information. STA3 can set its channel to idle and / or transmit.

[0136] Interference avoidance can be achieved through sectorized transmission using enhanced BSS colors. AP-STA pairs can indicate that the AP and STAs transmit using sectorized antennas. The initial omnidirectional transmission can indicate information including the use of sectorized transmission, BSS color / RA information, and / or direction of transmission. This information can be predetermined by the standard, or a discovery example / procedure can assign a direction to a specific sequence. The OBSS STA / AP can use this information to modify its CCA threshold during transmission and / or restrict the sectors it can use to transmit information to its receiver. This example may differ from the spatially orthogonal transmission proposed in 802.11ah. In 802.11ah, spatial orthogonality can be implicitly assumed. The BSS color can be used to send (e.g., explicitly send) information to the OBSS STA.

[0137] AP1 in BSS1 may transmit using an omni-directional antenna to indicate that it may use a particular sector. AP1 may transmit information about its BSS color and / or the sector to be used. For example, AP1 may send out a sector discovery frame. The AP may transmit a series of alternating omni-directional and / or sectorized transmissions. The omni-directional transmission frame may comprise sector ID and / or sector subcolor information, e.g., followed by the transmission of a null data packet in the sector of interest. This allows STAs within and outside the BSS (e.g., BSS1) to identify the sector and its sector subcolor.

[0138] An omni-directional frame can be transmitted by AP1, which can enable mapping of sector IDs to sector sub-colors. One or more (e.g., each) STA can reply to the AP with its preferred sector and / or corresponding sector sub-color. This can enable STAs in neighboring BSSs to map sector sub-colors to corresponding sectors.

[0139] STA1 can reply to AP1 with an ACK frame. The ACK frame can include an enhanced BSS color that can include information about one or more of the BSS in which transmissions may occur, the manner (e.g., sectorized antenna transmission), or the direction of transmission. AP1 can begin transmitting to STA1. STA2 in BSS2 can overhear the transmission from either AP1 or STA1. Based on the information that transmissions may occur in a separate BSS, STA2 can modify its CCA threshold for the duration of the transmission. Based on the information that transmissions may occur in a certain direction in BSS1, STA2 can modify its transmission manner. In an example, STA2 can stop transmitting, for example, if transmissions may occur in a certain direction in BSS1. In an example, STA2 can transmit to AP2 using lower transmit power or an orthogonal / semi-orthogonal sector direction, for example, if transmissions may occur in a certain direction in BSS1.

[0140] Enhanced BSS color can provide UL / DL OFDMA transmission and peer-to-peer (P2P) transmission. An AP can communicate with multiple STAs in the uplink and / or downlink, for example, using OFDMA. Pairs of STAs in the network can transmit directly to each other. The use of enhanced BSS color can facilitate transmission of data (e.g., simultaneous transmission) between the AP and STAs associated with the AP and between P2P STA pairs.

[0141] FIG. 20 shows an example of OFDMA transmission with peer-to-peer transmission using enhanced BSS color. FIG. 21 shows an example of packet exchange involving the entities in FIG. 20. As shown in FIGS. 20 and 21, AP1 can send information to STAs in its BSS, e.g., using OFDMA. For example, AP1 can initiate downlink OFDMA transmission with STA1 (e.g., using channel 1), STA2 (e.g., using channel 2), and STA3 (e.g., using channel 3) by sending an OFDMA schedule frame to one or more (e.g., all) STAs. Each of the STAs (e.g., STA1, STA2, and STA3) can reply with an OFDMA response frame (e.g., using a schACK frame). The AP can transmit data to the STAs. STAs that successfully receive the data can reply with an ACK.

[0142] The enhanced BSS color information can be transmitted in the SIG field of any (e.g., or all) of an OFDMA / COBRA channel reservation or schedule frame, one or more OFDMA / COBRA response frames, an OFDMA data frame, and / or one or more ACK frames. For example, the enhanced color information can include {1110}, indicating that a channel (e.g., channel 4) is silenced and available for use. As shown in FIG. 21 , a frame, such as an OFDMA / COBRA channel reservation or schedule frame, can be used to reserve one or more channel resources for OFDMA / COBRA transmission. The OFDMA / COBRA channel reservation or schedule frame can be used to indicate the subchannels to be used by one or more STAs (e.g., STA1, STA2, and STA3). An OFDMA / COBRA response frame from one or more STAs (e.g., each of STA1, STA2, and STA3) can be sent to acknowledge receipt of the schedule frame (e.g., using a schACK frame). One or more (e.g., each) STAs may send enhanced color information (e.g., the entire enhanced color information) to allow OBSS STAs close to the STA to obtain information about that STA (e.g., only the STA). For example, one or more (e.g., each) STAs may send (e.g., only send) basic BSS color information, information about a particular scheme, and / or information about subchannels that may have been assigned to it (e.g., only it). As discussed herein, Type I, Type II, and Type III color information may be used.

[0143] As shown in FIG. 21 , an OFDMA data frame can be sent from the AP (AP1) to one or more (e.g., each) of STA1, STA2, and STA3. An ACK frame can be sent from one or more (e.g., each) of STA1, STA2, and STA3. The transmitted enhanced color can be the same as that transmitted in the OFDMA schedule frame. The enhanced color information can be identical and can be transmitted in any or all of the frames in the OFDMA transmission frame exchange. STA4 in BSS1 can overhear the transmission from the AP (AP1). Upon decoding the preamble (e.g., an updated SIG field with the enhanced BSS color information), STA4 can access channel 4 and transmit a P2P frame to STA5. STA5 can continue by ACKing the received P2P frame.

[0144] Spatial orthogonal transmission can be achieved. Figure 22 shows an example of OBSS interference and interference cancellation transceiver schemes. For example, in a shopping mall or apartment building, adjacent BSSs may be densely deployed, where the coverage areas of adjacent BSSs overlap with each other. STAs within a BSS may be located within the overlapping coverage areas of two or more BSSs. As shown in Figure 22, STA2 belonging to a BSS, e.g., BSS1, may be located within the coverage area of ​​an OBSS, e.g., BSS2, as well as within the coverage area of ​​that BSS. AP2 within the OBSS may transmit signals to its associated STAs, such as STA3 and STA4 in Figure 22. STA2 cannot communicate with APs within STA2's BSS, e.g., AP1, for the duration of the NAV set by AP2. STA2 may need to be idle for the duration of the AP2 transmission.

[0145] The examples described herein may enable STA2 to transmit and / or receive under certain conditions, as shown in FIG. 22. For example, STA2 may use a high-throughput long training field (HT-LTF) or a very high-throughput long training field (VHT-LTF) in transmissions from AP2 to estimate the interference channel, for example, between AP2 and STA2. This interference channel state information may be utilized to assist STA2 in communication (e.g., simultaneous communication) with AP1 for the duration of AP2's NAV duration. Multiple antenna configurations may be utilized for AP1, AP2, and STA2. As described herein, the BSS color field in the SIG field may be used to identify information from the BSS.

[0146] A STA can identify interfering transmissions from APs in an OBSS and coordinate its communication (e.g., simultaneous communication) with APs in its own BSS as described herein. As shown in FIG. 22, in an OBSS, AP2 can initialize communication with its associated STA3 and STA4. The BSS color and the total number of spatial streams can be indicated in the SIG field of the preamble. STA2 can associate with AP1. STA2 can listen for RTSs from AP2 and / or prepare to receive signals from AP2. STA2 can receive data packets from AP2. STA2 can choose to estimate the channel and / or check the BSS color field. STA2 can determine that the BSS color does not match the BSS color of the AP with which it can associate. If STA2 misses the RTS sent by AP1 or the OBSS does not use RTS / CTS frame exchange, STA2 can track the start of the packet by detecting the STF on the interfered channel. When a packet start point is detected, STA2 can estimate the channel and / or check the BSS color field. The BSS color information allows STA2 to know that the transmission may be within the OBSS. STA2 can choose to stop packet detection on the interfered channel and / or remain muted during transmission within the OBSS, e.g., due to power consumption limitations. STA2 can calculate the spatial direction in the null space of the interfering signal. STA2 can select a CDMA-encoded signal and / or a feedback channel to send to AP1 in an orthogonal direction toward the interfering channel. AP1 can receive feedback information from STA2. AP1 can perform precoding, e.g., at the receiver of STA2, to control its transmitted signal to a spatial direction that may be orthogonal to the subspace occupied by the interfering signal.STA2 can receive signals from AP1, for example, within the NAV duration of AP2, using a receiver that combines weights consistent with the transmission direction of AP1.

[0147] The orthogonal directions can be determined as described herein. AP2 uses M antennas to receive the interference signal x I AP1 and STA2 may have (e.g., may need to have) N>M antennas. STA2 may perform channel estimation using, for example, the preamble portion of the packet sent by AP2. The estimated interference channel between STA2 and AP2 is expressed as an N×M matrix H I STA2 can be expressed as H I We can compute the SVD decomposition of H I =UΣV=[U1U2]ΣV where U can be an N×N unitary matrix, V can be an M×M unitary matrix, and Σ can be an N×M matrix with singular values ​​on its top main diagonal. U1 is H I U2 can be an N×M submatrix of U that holds eigenvectors that can span the range space of H. I It can be an N×(NM) submatrix that can lie in the null space of

[0148]

number

[0149] where

[0150]

number

[0151] , i=1,2,...,NM can be column vectors of U2, and STA2 can select some column vectors of U2 as desired beamforming vectors. STA2 can notify AP1 to transmit signals using these desired beamforming vectors.

[0152] As the desired beamforming vector,

[0153]

number

[0154] Assuming that K column vectors are selected in D STA2 can form U D The N×N channel matrix between AP1 and STA2 is H D AP1 may have knowledge of the CSI between itself and STA2. AP1 may, for example, during transmission, use the precoding matrix

[0155]

number

[0156] STA2 receives K information symbols x D The received signal at STA2 can be expressed as: y=H D P D x D +H I x I +n =U D x D +H I x I +n

[0157] At the receiver, STA2:

[0158]

number

[0159] can be used as the coupling matrix. The desired signal beamforming vector U D x D can exist in the null space of the interfering signal, and the combining matrix can be matched to the desired signal, so that the interference can be removed (e.g., completely removed) after a combining operation such as

[0160]

number

[0161] for example

[0162]

number

[0163] Since can be composed of several column vectors of a unitary matrix, the equivalent noise variance cannot be strong. The calculation value of SVD at STA2 may be low. There may be more calculation cost in the beamforming process at AP1. The interference direction U by STA2 D The feedback of STA2 may cause interference to closely located STAs associated with AP2. To reduce STA2's interference to STAs in adjacent OBSSs, CDMA coded feedback or a separate frequency feedback channel may be useful. To reduce the interference caused by STA2, transmit power control may be used.

[0164] BSS color changes and coordination may be described herein. Figure 23 shows an example of an OBSS Report element. A STA may detect a BSS other than its own, for example, using the color of its current BSS and comparing it to the color indicated in a received transmission (e.g., in a SIG field). The STA may report such detection to its associated AP. For example, a STA may use the OBSS Report element as shown in Figure 23 to report information about OBSSs and / or BSS colors that the STA may have detected.

[0165] An OBSS Report element (e.g., an OBSS (sub)element) may include one or more of the following fields: (sub)element ID, length, number of fields, or OBSS Report Field 1 to Field N. The (sub)element ID may include an identifier that the current (sub)element may be an OBSS Report (sub)element. The length field may include the length of the OBSS Report (sub)element. The number of fields field may indicate the number of OBSS Report fields in the current OBSS Report (sub)element. The number of fields field may be omitted, for example, if a fixed number (e.g., one) of OBSS Report fields is included. One or more (e.g., each) OBSS Report Field 1 to Field N fields may include information associated with the detected OBSS. One or more (e.g., each) of the OBSS Report fields may include one or more of the following subfields: BSS identifier, ESS identifier, coordinator ID, generation, color information, or operating channel information. The BSS identifier subfield may comprise an identifier of the BSS, such as a BSSID, short BSSID, or other type of BSS identifier that may have been agreed upon in advance. The ESS Identifier subfield may comprise an identifier of the ESS, such as an SSID, short SSID, or other type of BSS identifier. The Coordinator ID subfield may comprise an identifier of the coordinator for the identified BSS and / or ESS. The ID may be implemented as a MAC address, IP address, etc. The Generation subfield may comprise an indication of the generation of the identified BSS. Possible generation values ​​may include 802.11a, 802.11b, 802.11g, 802.11n, 802.11ac, 802.11ah, 802.11af, 802.11ax, etc. The Color Information subfield may comprise information of BSS colors that can be used by the identified BSS. Possible values ​​may include no color and / or an integer or bit pattern indicating colors that can be used by the identified BSS.A particular value or bit pattern in this subfield can indicate No Color, or that the identified BSS does not use color. The Operating Channel Information subfield can include the operating channel of the identified BSS, such as the BSS operating width, such as 20 MHz, 40 MHz, 80 MHz, 160 MHz, 80+80 MHz, 1 MHz, 2 MHz, W, W+W, 2W, 4 MHz, 2W+2W, 8 MHz, 16 MHz, etc. The primary channel number and CCFS-1 information can be included.

[0166] The OBSS Report (sub)element, or a set of fields and / or subfields, can be implemented as any part of an existing element, such as an HE Capability element, an HE Operation element, or as any part of a Control, Management, Extended, or Null Data Packet (NDP) frame, or as part of a MAC or Physical Layer Convergence Protocol (PLCP) header. For example, the set of fields or subfields of the OBSS Report (sub)element can be implemented as part or subelement of a Neighbor Report, a Reduced Neighbor Report, or an HE Neighbor Report. For example, one or more of the fields or subfields described herein can be included in a public action frame, such as an Action frame, a No-ACK Action frame, or an HE Action frame. Such a frame can be used by a STA to report one or more discovered BSSs, including whether the discovered BSSs may use color and which color values ​​the discovered BSSs may use.

[0167] BSS color changes can occur. STAs can be informed by an AP of the BSS colors that may be used in the AP's BSS during association. STAs can send an OBSS Report action frame, or a frame with an OBSS Report (sub)element, solicited, periodically, or unsolicited by the AP to report that a BSS can be discovered by STAs that may use the same color. For example, a STA can send an OBSS Report action frame, or a frame containing an OBSS Report (sub)element, solicited, periodically, or unsolicited by the AP to report one or more OBSSs that the STA may discover. An AP can detect that one of its OBSSs uses the same color as its own BSS by detecting OBSS packets, such as beacons, short beacons, data, and control, management, or extension packets from the OBSS. OBSS packets can include the color of the OBSS and / or other identifying information, such as the BSSID or MAC address of a transmitting STA that does not belong to the AP's own BSS. For example, when an AP receives an indication from a STA that an OBSS may use the same color as its own BSS, the AP can select a different color. The new color value can be selected randomly, e.g., from a set of color values ​​that may not be used by its direct OBSS. The new color value can be selected to be the color value least used by OBSSs in a given area. The AP can announce the BSS color change using a color announcement frame change, which can be implemented as a (sub)element in the beacon, short beacon, or any part of the management, control, or extension, NDP frame, or as part of the MAC / PLCP header.

[0168] FIG. 24 shows an example of a color change announcement element (e.g., (sub)element). As shown in FIG. 24, the color change announcement element (e.g., (sub)element) may include one or more of the following fields: (sub)element ID, length, new BSS color, or switch time. The (sub)element ID field may be an identifier indicating that the current (sub)element may be a color change announcement (sub)element. The length field may comprise the length of the color change (sub)element. The new BSS color may comprise the value of a new color value that can be used by the BSS. The switch time field may indicate the time of switching to the new BSS color. For example, the switch time may be implemented as the remaining time in time units (TUs), microseconds, milliseconds, seconds, or any other time unit until the BSS can switch to the new BSS color value. For example, the switch time may be a timing synchronization function (TSF) value, a fractional TSF value, or an absolute time during which the BSS can change to the new BSS color value. The APs and STAs of the BSS may adapt to and / or use the new BSS color value at the indicated switch time and / or when the switch time may count down to zero.

[0169] One or more APs can select a color (e.g., the best color) for their BSS using cooperation. Cooperation can be described herein. An AP can select a new BSS color value through cooperation, for example, when starting a new BSS, when it discovers that an OBSS can use the same color value as their current BSS, when it is notified by its STAs that one or more OBSSs can use the same color value as their own BSS, and / or when it experiences interference above a certain threshold level. An AP can select a new BSS color value through cooperation, for example, through AP-to-AP cooperation or through cooperation through a provider coordinator.

[0170] An AP or a coordinator can send a collaboration request frame / element to one or more (e.g., all) APs / coordinators in, for example, an associated area. The collaboration request frame can comprise a color value. The collaboration request can inquire about colors that can be used by one or more (e.g., all) of the APs / BSSs in the associated BSS.

[0171] When the AP / coordinator receives a collaboration request frame / element, for example to collaborate on color values, it can respond with a collaboration response frame / element. The collaboration response frame / element can include a status of whether the proposed color in the collaboration request frame was rejected, accepted, or an alternate value was proposed. The collaboration response can include, in the responding BSS, the current color value that can be used by the BSS.

[0172] The AP / coordinator may announce to its BSS or one or more BSSs that the BSS should switch to a new BSS color value at the resulting switch time, for example using a color change frame / element.

[0173] 25A is a diagram of an example communications system 2500 in which one or more disclosed embodiments can be implemented. The communications system 2500 can be a multiple-access system that provides content, such as voice, data, video, messaging, broadcasts, etc., to multiple wireless users. The communications system 2500 can enable the multiple wireless users to access such content through sharing of system resources, including wireless bandwidth. For example, the communications system 2500 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), etc.

[0174] 25A, the communications system 2500 may include at least one wireless transmit / receive unit (WTRU), such as multiple WTRUs, e.g., WTRUs 2502a, 2502b, 2502c, and 2502d, a radio access network (RAN) 2504, a core network 2506, a public switched telephone network (PSTN) 2508, the Internet 2510, and other networks 2512, although it should be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 2502a, 2502b, 2502c, 2502d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, WTRUs 2502a, 2502b, 2502c, 2502d 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 (PDAs), smartphones, laptops, notebooks, personal computers, wireless sensors, consumer electronic devices, etc.

[0175] The communications system 2500 may also include a base station 2514a and a base station 2514b. Each of the base stations 2514a, 2514b may be any type of device configured to wirelessly interface with at least one of the WTRUs 2502a, 2502b, 2502c, 2502d to facilitate access to one or more communications networks, such as the core network 2506, the Internet 2510, and / or the network 2512. By way of example, the base stations 2514a, 2514b may be a base transceiver station (BTS), a Node B, an eNodeB, a Home Node B, a Home eNodeB, a site controller, an access point (AP), a wireless router, etc. While the base stations 2514a, 2514b are each shown as a single element, it should be understood that the base stations 2514a, 2514b may include any number of interconnected base stations and / or network elements.

[0176] The base station 2514a can be part of the RAN 2504, which can also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 2514a and / or base station 2514b can be configured to transmit and / or receive wireless signals within a particular geographic area, which can be referred to as a cell (not shown). A cell can be further divided into cell sectors. For example, the cell associated with the base station 2514a can be divided into three sectors. Thus, in one embodiment, the base station 2514a can include three transceivers, e.g., one for each sector of the cell. In other embodiments, the base station 2514a can use multiple-input multiple-output (MIMO) technology and thus utilize multiple transceivers for each sector of the cell.

[0177] The base stations 2514a, 2514b may communicate with one or more of the WTRUs 2502a, 2502b, 2502c, 2502d over an air interface 2516, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 2516 may be established using any suitable radio access technology (RAT).

[0178] More specifically, as noted above, the communications system 2500 may be a multiple-access system and may use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 2514a and the WTRUs 2502a, 2502b, 2502c in the RAN 2504 may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 2516 using Wideband CDMA (WCDMA). WCDMA may include communications 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).

[0179] In other embodiments, the base station 2514a and the WTRUs 2502a, 2502b, 2502c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 2516 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A).

[0180] In other embodiments, the base station 2514a and the WTRUs 2502a, 2502b, 2502c may implement a radio technology such as IEEE 802.16 (e.g., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data Rates for GSM Evolution (EDGE), GSM EDGE (GERAN), or the like.

[0181] The base station 2514b of FIG. 25A may comprise, for example, a wireless router, a Home NodeB, a Home eNodeB, or an access point and may utilize any suitable RAT for facilitating wireless connectivity in a local area, such as a business, home, vehicle, campus, etc. In one embodiment, the base station 2514b and the WTRUs 2502c, 2502d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In another embodiment, the base station 2514b and the WTRUs 2502c, 2502d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In another embodiment, the base station 2514b and the WTRUs 2502c, 2502d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish a picocell or femtocell. 25A, base station 2514b may have a direct connection to the Internet 2510. Thus, base station 2514b may not need to access the Internet 2510 via core network 2506.

[0182] The RAN 2504 can communicate with a core network 2506, which can be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 2502a, 2502b, 2502c, 2502d. For example, the core network 2506 can provide call control, billing services, mobile location-based services, prepaid calls, Internet connectivity, video distribution, etc., and / or perform high-level security functions such as user authentication. Although not shown in FIG. 25A , it should be understood that the RAN 2504 and / or core network 2506 can communicate, directly or indirectly, with other RANs that use the same RAT as the RAN 2504 or a different RAT. For example, in addition to being connected to the RAN 2504, which can utilize E-UTRA radio technology, the core network 2506 can also communicate with another RAN (not shown) that uses GSM radio technology.

[0183] The core network 2506 can also serve as a gateway for the WTRUs 2502a, 2502b, 2502c, 2502d to access the PSTN 2508, the Internet 2510, and / or other networks 2512. The PSTN 2508 can include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 2510 can include a global system 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. The network 2512 can include wired or wireless communication networks owned and / or operated by other service providers. For example, the network 2512 can include another core network connected to one or more RANs, which can use the same RAT as the RAN 2504 or a different RAT.

[0184] Some or all of the WTRUs 2502a, 2502b, 2502c, 2502d in the communications system 2500 may include multi-mode capabilities, e.g., the WTRUs 2502a, 2502b, 2502c, 2502d may include multiple transceivers for communicating with different wireless networks over different wireless links. For example, the WTRU 2502c shown in FIG. 25A may be configured to communicate with a base station 2514a that may use cellular-based wireless technology and a base station 2514b that may use IEEE 802 wireless technology.

[0185] Figure 25B is a system diagram of an example WTRU 2502. As shown in Figure 25B, the WTRU 2502 may include a processor 2518, a transceiver 2520, a transmit / receive element 2522, a speaker / microphone 2524, a keypad 2526, a display / touchpad 2528, non-removable memory 2530, removable memory 2532, a power source 2534, a global positioning system (GPS) chipset 2536, and other peripherals 2538. It should be understood that the WTRU 2502 may include any subcombination of the above elements while remaining consistent with an embodiment.

[0186] The processor 2518 may comprise a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 2518 may perform signal coding, data processing, power control, input / output processing, and / or any other function that enables the WTRU 2502 to operate in a wireless environment. The processor 2518 may be coupled to the transceiver 2520, which may be coupled to the transmit / receive element 2522. While FIG. 25B depicts the processor 2518 and the transceiver 2520 as separate components, it should be understood that the processor 2518 and the transceiver 2520 may be integrated together in an electronic circuit package or chip.

[0187] The transmit / receive element 2522 can be configured to transmit signals to or receive signals from a base station (e.g., base station 2514a) over the air interface 2516. For example, in one embodiment, the transmit / receive element 2522 can be an antenna configured to transmit and / or receive RF signals. In other embodiments, the transmit / receive element 2522 can be an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, for example. In yet other embodiments, the transmit / receive element 2522 can be configured to transmit and receive both RF and light signals. It should be understood that the transmit / receive element 2522 can be configured to transmit and / or receive any combination of wireless signals.

[0188] 25B shows the transmit / receive element 2522 as a single element, the WTRU 2502 may include any number of transmit / receive elements 2522. More particularly, the WTRU 2502 may use MIMO technology. Thus, in one embodiment, the WTRU 2502 may include two or more transmit / receive elements 2522 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 2516.

[0189] The transceiver 2520 may be configured to modulate signals to be transmitted by the transmit / receive element 2522 and to demodulate signals received by the transmit / receive element 2522. As mentioned above, the WTRU 2502 may have multi-mode capabilities. Thus, the transceiver 2520 may include multiple transceivers to enable the WTRU 2502 to communicate over multiple RATs, such as UTRA and IEEE 802.11.

[0190] The processor 2518 of the WTRU 2502 may be coupled to and may receive user input data from a speaker / microphone 2524, a keypad 2526, and / or a display / touchpad 2528 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 2518 may also output user data to the speaker / microphone 2524, the keypad 2526, and / or the display / touchpad 2528. Further, the processor 2518 may access information from and store data in any type of suitable memory, such as non-removable memory 2530 and / or removable memory 2532. The non-removable memory 2530 may include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 2532 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 2518 may access information from and store data in memory that is not physically located on the WTRU 2502, such as on a server or home computer (not shown).

[0191] The processor 2518 may receive power from a power source 2534 and may be configured to distribute and / or control the power to other components within the WTRU 2502. The power source 2534 may be any suitable device for powering the WTRU 2502. For example, the power source 2534 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0192] The processor 2518 may also be coupled to a GPS chipset 2536, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 2502. In addition to or instead of information from the GPS chipset 2536, the WTRU 2502 may receive location information from a base station (e.g., base stations 2514a, 2514b) over the air interface 2516 and / or may determine its location based on the timing of signals received from two or more nearby base stations. It should be understood that the WTRU 2502 may obtain location information by way of any suitable location determination method while remaining consistent with an embodiment.

[0193] The processor 2518 may further be coupled to other peripherals 2538, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 2538 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos or videos), a Universal Serial Bus (USB) port, a vibration device, a television receiver / transmitter, a hands-free headset, a Bluetooth module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an internet browser, etc.

[0194] Although features and elements have been described above in particular combinations, those skilled in the art will 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 protocol described herein, the features and elements described herein may be applicable to other wireless systems. While the features and elements described herein may be described for uplink operation, the methods and procedures may be applicable to downlink operation. While SIFS may be used herein to indicate various frame intervals, other frame intervals, such as RIFS or other agreed-upon time intervals, may apply. Furthermore, the methods described herein may be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted over wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random-access memory (RAM), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor in association with software can be employed to implement a radio frequency transceiver for use in a WTRU, terminal equipment, base station, RNC, or any host computer.

Claims

1. A station (STA), a processor; a transmitter / receiver; The processor and the transceiver receiving, from an access point (AP) with which the STA is associated, an indication of a first basic service set (BSS) color associated with the AP; receiving a request frame from the AP with which the STA is associated, in which the STA collects BSS color information for one or more overlapped BSSs (OBSSs); receiving beacons from one or more APs associated with the one or more OBSSs, the beacons including an indication of the respective BSS colors; transmitting one or more high efficiency (HE) operation elements in response to the request frame, the HE operation elements including the collected BSS color information for the one or more OBSSs, the collected BSS color information including a BSS color for each of the one or more OBSSs; receiving a BSS color change announcement element from the AP in the BSS with which the STA is associated, the BSS color information field indicating the first BSS color of the AP and a second BSS color determined based on the transmitted BSS color information of the one or more OBSSs, and the color switch time field indicating when the AP will switch to the second BSS color; After the AP switches to the second BSS color, the second BSS color is used in a SIG field of a PHY layer preamble of a packet communicated with the AP. STA configured as follows.

2. 2. The STA of claim 1, wherein the processor and the transceiver are further configured to transmit an event report to the AP indicating that a BSS color collision has been detected by the STA based on at least one identical BSS color of the one or more OBSSs.

3. The STA of claim 2 , wherein the event report further includes information of the one or more OBSSs associated with a plurality of neighboring BSSs detected by the STA.

4. The STA of claim 2 , wherein the event report is transmitted by the STA in an unsolicited manner.

5. The STA of claim 2 , wherein the BSS color change announcement element is received in response to the event report.

6. 1. A method implemented in a station (STA), comprising: receiving, from an access point (AP) with which the STA is associated, an indication of a first basic service set (BSS) color associated with the AP; receiving a request frame from the AP with which the STA is associated, for the STA to collect BSS color information for one or more overlapped BSSs (OBSSs); receiving beacons from one or more APs associated with the one or more OBSSs, the beacons including an indication of the respective BSS colors; transmitting, in response to the request frame, one or more high efficiency (HE) operation elements including the collected BSS color information of the one or more OBSSs, the collected BSS color information including a BSS color of each of the one or more OBSSs; receiving a BSS color change announcement element from the AP in the BSS with which the STA is associated, the BSS color information field indicating the first BSS color of the AP and a second BSS color determined based on the transmitted BSS color information of the one or more OBSSs, and the color switch time field indicating when the AP will switch to the second BSS color; using the second BSS color in a SIG field of a PHY layer preamble of packets communicated with the AP after the AP has switched to the second BSS color; A method for providing the above.

7. sending an event report to the AP indicating that a BSS color collision has been detected by the STA based on at least one identical BSS color of the one or more OBSSs; The method of claim 6 further comprising:

8. The method of claim 7 , wherein the event report further includes information of the one or more OBSSs associated with a plurality of neighboring BSSs detected by the STA.

9. The method of claim 7 , wherein the event report is transmitted by the STA in an unsolicited manner.

10. The method of claim 7 , wherein the BSS color change announcement element is received in response to the event report.

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