Transmitter-based link adaptation

Abstract

Methods, devices, and systems for link adaptation in wireless communications. Some implementations particularly relate to transmitter-based modulation and coding scheme (MCS) selection. A transmitting device transmits a test packet over a wireless channel to a receiving device. The receiving device generates one or more signal to interference plus noise ratio (SINR) estimates for the wireless channel based on the received sounding packet. In some aspects, each SINR estimate may be associated with a particular modulation order. In other aspects, each SINR estimate may be generated based on a transmitter configuration or receiver type to be used for subsequent communications between the transmitting device and the receiving device. The receiving device transmits feedback to the transmitting device, the feedback including the SINR estimates. The transmitting device then selects an MCS to be used for subsequent communications with the receiving device based on the SINR estimates and associated modulation orders.

Description

[0001] This application is a divisional application of a patent application with an international application date of November 10, 2020, an international application number of PCT / US2020 / 059790, a Chinese national application date of November 10, 2020, an application number of 202080079085.0, and an invention name of “Transmitter-based link adaptation”. Technical Field

[0002] The present disclosure relates generally to wireless communications and, more particularly, to transmitter-based link adaptation in wireless communication systems.

[0003] Related technical description

[0004] A wireless local area network (WLAN) may be formed by one or more access points (APs) that provide a shared wireless communication medium for use by several client devices, also referred to as stations (STAs). The basic building block of a WLAN that complies with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards is a basic service set (BSS) managed by an AP. Each BSS is identified by a basic service set identifier (BSSID) announced by the AP. The AP periodically broadcasts beacon frames to enable any STA within the wireless range of the AP to establish or maintain a communication link with the WLAN.

[0005] During wireless data transmission from a transmitting device to a receiving device, imperfect channel conditions on the wireless communication medium may result in data loss. If the receiving device does not receive (or fails to decode) one or more portions of the transmitted data, the transmitting device may retransmit the one or more portions of the data until they are received and correctly decoded by the receiving device. Data retransmissions may consume time and the limited resources of the wireless communication medium, and therefore it is desirable to minimize the number of such data retransmissions.

[0006] Link adaptation is a technique for adapting modulation, coding or other signaling parameters to the channel conditions on the wireless medium. An optimized modulation and coding scheme (MCS) can help reduce retransmissions on the wireless medium. In an example technique for determining channel conditions, a transmitting device transmits a "probing" packet to a receiving device on the wireless medium. The receiving device estimates the channel conditions based on the received probing packets and feeds back channel state information (CSI) to the transmitting device. The transmitting device selects the MCS to be used for subsequent data transmissions to the receiving device based on the CSI. Thus, the optimal MCS selection may depend on the details and accuracy of the CSI reported by the receiving device.

[0007] Overview

[0008] The systems, methods, and devices of the disclosure each have several innovative aspects, no single one of which is solely responsible for the desirable attributes disclosed herein.

[0009] An innovative aspect of the subject matter described in the present disclosure may be implemented as a wireless communication method. The method may be performed by a wireless communication device and may include: transmitting a first packet to a receiving device on a wireless channel; receiving feedback from the receiving device in response to the first packet, wherein the feedback includes one or more signal-to-interference-plus-noise ratio (SINR) estimates associated with the wireless channel; determining a corresponding modulation order associated with each of the one or more SINR estimates; and selecting a modulation and coding scheme (MCS) to be used for subsequent communications with the receiving device based on the one or more SINR estimates and the corresponding modulation order associated with each of the one or more SINR estimates.

[0010] In some implementations, the feedback includes information indicating a modulation order associated with each of the one or more SINR estimates. In some implementations, the method further includes transmitting a second packet to the receiving device based on the selected MCS, wherein the second packet is transmitted on a number (N) of spatial streams. In some aspects, the first packet may be transmitted on the N spatial streams. In some other aspects, the first packet may be transmitted on a number (M) of spatial streams different from the second packet. In some implementations, the method further includes transmitting a third packet to the receiving device before transmitting the first packet, the third packet carrying information indicating the N spatial streams. In some implementations, the first packet is a null data packet (NDP) and the third packet is an NDP announcement (NDPA) associated with the NDP.

[0011] In some implementations, the one or more SINR estimates include multiple SINR estimates, wherein each SINR estimate in the multiple SINR estimates is associated with a different modulation order. In some implementations, determining the modulation order includes: determining an arrangement of the multiple SINR estimates in the received feedback, and the modulation order associated with each SINR estimate is determined based on the arrangement of the multiple SINR estimates. In some implementations, selecting the MCS includes: estimating a corresponding throughput of the communication associated with each SINR estimate based on the modulation order associated with each SINR estimate in the multiple SINR estimates, and the MCS is selected based on the estimated throughput associated with the multiple SINR estimates.

[0012] Another innovative aspect of the subject matter described in the present disclosure may be implemented in a wireless communication device. In some implementations, the wireless communication device may include at least one modem, at least one processor communicatively coupled to the at least one modem, and at least one memory communicatively coupled to the at least one processor and storing processor-readable code. In some implementations, execution of the processor-readable code by the at least one processor causes the wireless communication device to perform operations including: transmitting a first packet to a receiving device on a wireless channel; receiving feedback from the receiving device in response to the first packet, wherein the feedback includes one or more SINR estimates associated with the wireless channel; determining a corresponding modulation order associated with each of the one or more SINR estimates; and selecting an MCS to be used for subsequent communications with the receiving device based on the one or more SINR estimates and the corresponding modulation order associated with each of the one or more SINR estimates.

[0013] Another innovative aspect of the subject matter described in the present disclosure may be implemented as a wireless communication method. The method may be performed by a wireless communication device and may include: receiving a first packet from a transmitting device on a wireless channel; determining a receiver type to be used to receive subsequent communications from the transmitting device; generating one or more SINR estimates associated with the wireless channel based on receiving the first packet and the receiver type to be used to receive subsequent communications; and transmitting feedback to the transmitting device, the feedback including at least one of the one or more SINR estimates.

[0014] In some implementations, the receiver type is a minimum mean square error (MMSE) receiver type or a maximum likelihood ratio (ML) receiver type. In some implementations, generating the one or more SINR estimates includes: determining a corresponding SINR for each of a plurality of tones of the wireless channel; determining a corresponding channel capacity for each of the plurality of tones based on the determined SINR for each tone; calculating a linear average of the determined channel capacities; and mapping the linear averages to one or more constrained capacity curves associated with one or more modulation orders, respectively, wherein each of the one or more SINR estimates is determined based on the mapping of the linear average to the corresponding constrained capacity curve.

[0015] In some implementations, the feedback further includes information indicating a corresponding modulation order associated with each of the one or more SINR estimates. In some implementations, the one or more SINR estimates include multiple SINR estimates, wherein each of the multiple SINR estimates is associated with a different modulation order. In some aspects, the method may further include: estimating a corresponding throughput associated with each SINR estimate of the communication based on the modulation order associated with each of the multiple SINR estimates; and selecting one of the multiple SINR estimates to be included in the feedback based on the estimated throughput associated with each of the multiple SINR estimates. In some other aspects, the feedback may include the multiple SINR estimates. In some implementations, the method further includes arranging the multiple SINR estimates in the feedback according to the modulation order associated with each SINR estimate.

[0016] In some implementations, the method further includes receiving a second packet from the transmitting device before receiving the first packet, wherein the second packet carries information indicating a number of spatial streams associated with subsequent communications; and adjusting each of the one or more SINR estimates based on the number of spatial streams associated with the subsequent communications. In some implementations, the first packet is an NDP and the second packet is an NDPA associated with the NDP.

[0017] Another innovative aspect of the subject matter described in the present disclosure may be implemented in a wireless communication device. In some implementations, the wireless communication device may include at least one modem, at least one processor communicatively coupled to the at least one modem, and at least one memory communicatively coupled to the at least one processor and storing processor-readable code. In some implementations, execution of the processor-readable code by the at least one processor causes the wireless communication device to perform operations including: receiving a first packet from a transmitting device on a wireless channel; determining a receiver type to be used to receive subsequent communications from the transmitting device; generating one or more SINR estimates associated with the wireless channel based on receiving the first packet and the receiver type to be used to receive subsequent communications; and transmitting feedback to the transmitting device, the feedback including at least one of the one or more SINR estimates. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Details of one or more implementations of the subject matter described in the present disclosure are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages will become apparent from the description, drawings, and claims. It should be noted that the relative sizes of the following drawings may not be drawn to scale.

[0020] Figure 1A schematic diagram of an example wireless communication network is shown.

[0021] Figure 2 An example protocol data unit (PDU) that may be used for communications between an access point (AP) and a number of stations (STAs) is shown.

[0022] Figure 3A An example physical layer (PHY) preamble that may be used for communications between an AP and each of a number of STAs is shown.

[0023] Figure 3B Another example PHY preamble that may be used for communications between an AP and each of a number of stations is shown.

[0024] Figure 4 An example physical layer convergence protocol (PLCP) protocol data unit (PPDU) that may be used for communication between an AP and several STAs is shown.

[0025] Figure 5 A block diagram of an example wireless communication device is shown.

[0026] Fig. 6A A block diagram of an example access point (AP) is shown.

[0027] Figure 6B A block diagram of an example station (STA) is shown.

[0028] Figure 7 Shown is a sequence diagram illustrating an example message exchange between a transmitting device and a receiving device according to some implementations.

[0029] Figure 8 Shown is a sequence diagram illustrating another example message exchange between a transmitting device and a receiving device according to some implementations.

[0030] Fig. 9 A flow chart illustrating an example process for wireless communications supporting transmitter-based link adaptation according to some implementations is shown.

[0031] Fig. 10A A flow chart illustrating an example process for wireless communications supporting transmitter-based link adaptation according to some implementations is shown.

[0032] Fig. 10B A flow chart illustrating an example process for wireless communications supporting transmitter-based link adaptation according to some implementations is shown.

[0033] Fig.11 A block diagram of an example wireless communication device is shown in accordance with some implementations.

[0034] Fig.12A block diagram of an example wireless communication device is shown in accordance with some implementations.

[0035] Like reference numbers and designations in the various drawings indicate like elements. Detailed Description

[0037] The following description is directed to certain implementations and is intended to describe the innovative aspects of the present disclosure. However, one of ordinary skill in the art will readily recognize that the teachings herein can be applied in many different ways. The described implementations can be implemented in a manner that is capable of being implemented in accordance with the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, the IEEE 802.15 standard, the Bluetooth Special Interest Group (SIG), or the like. The described implementations may be implemented in any device, system, or network capable of transmitting and receiving radio frequency (RF) signals according to one or more of the Long Term Evolution (LTE), 3G, 4G, or 5G (New Radio (NR)) standards, or the like released by the Third Generation Partnership Project (3GPP). The described implementations may be implemented in any device, system, or network capable of transmitting and receiving RF signals according to one or more of the following technologies or techniques: code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), single user (SU) multiple input multiple output (MIMO), and multi-user (MU) MIMO. The described implementations may also be implemented using other wireless communication protocols or RF signals suitable for use in one or more of a wireless personal area network (WPAN), a wireless local area network (WLAN), a wireless wide area network (WWAN), or an Internet of Things (IOT) network.

[0038] Various aspects generally relate to link adaptation in wireless communication systems, and more particularly to transmitter-based modulation and coding scheme (MCS) selection. In some aspects, a transmitting device may transmit a test packet (such as a sounding packet) to a receiving device on a wireless channel. The receiving device may generate multiple signal-to-interference-plus-noise ratio (SINR) estimates for the wireless channel based on the received test packet. In some aspects, each SINR estimate may be associated with a specific corresponding modulation order selected from a set with multiple possible modulation orders (such as BPSK, QPSK, or M-QAM). In some other aspects, each SINR estimate may be generated based on a transmitter configuration (such as the number of spatial streams) or a receiver type (such as MMSE or ML) to be used for subsequent communications by the transmitting device and the receiving device, respectively. The receiving device may then transmit feedback to the transmitting device, the feedback including at least one of the SINR estimates associated with the specific corresponding modulation order. In some implementations, the receiving device may transmit multiple or all of the SINR estimates to the transmitting device. The transmitting device may then select an MCS to be used for subsequent communications with the receiving device based on the one or more SINR estimates and the corresponding modulation order.

[0039] Specific implementations of the subject matter described in the present disclosure may be implemented to achieve one or more of the following potential advantages. In some implementations, the described techniques may be used to increase the data rate and throughput of communications on wireless channels. By determining the modulation order associated with each SINR estimate reported by the receiving device, the transmitting device may make a more informed MCS selection based on the current channel conditions. For example, the transmitting device may select the MCS that produces the maximum throughput for the current channel conditions based on the reported SINR estimate and the associated modulation order. In addition, by adjusting the SINR estimate based on the transmitter configuration or receiver type to be used for subsequent communications (rather than just when the channel is sounded), the receiving device can ensure that the reported SINR estimate is relevant to the data transmission they are intended to carry out. Accordingly, various aspects of the present disclosure enable the transmitting device to select an MCS that is more closely customized for the channel conditions and device configuration when transmitting data to the receiving device.

[0040] Figure 1A block diagram of an example wireless communication network 100 is shown. According to some aspects, the wireless communication network 100 may be an example of a wireless local area network (WLAN) such as a Wi-Fi network (and will be referred to as WLAN 100 hereinafter). For example, the WLAN 100 may be a network that implements at least one of the IEEE 802.11 family of wireless communication protocol standards, such as standards defined by the IEEE 802.11-2016 specification or its revisions, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be. The WLAN 100 may include numerous wireless communication devices, such as an access point (AP) 102 and a plurality of stations (STAs) 104. Although only one AP 102 is shown, the WLAN network 100 may also include a plurality of APs 102.

[0041] Each STA 104 may also be referred to as a mobile station (MS), a mobile device, a mobile handset, a wireless handset, an access terminal (AT), a user equipment (UE), a subscriber station (SS), or a subscriber unit, etc. STA 104 may represent a variety of devices, such as mobile phones, personal digital assistants (PDAs), other handheld devices, netbooks, netbook computers, tablet computers, laptops, display devices (e.g., TVs, computer monitors, navigation systems, etc.), music or other audio or stereo equipment, remote control devices (“remote controls”), printers, kitchen or other home appliances, key fobs (e.g., for passive keyless entry and start (PKES) systems), etc.

[0042] A single AP 102 and the associated set of STAs 104 may be referred to as a basic service set (BSS), which is managed by the respective AP 102 . Figure 1Additionally shown is an example coverage area 106 of the AP 102, which may represent a basic service area (BSA) of the WLAN 100. The BSS may be identified to users by a service set identifier (SSID) and may also be identified to other devices by a basic service set identifier (BSSID), which may be a media access control (MAC) address of the AP 102. The AP 102 periodically broadcasts a beacon frame (“beacon”) including the BSSID to enable any STA 104 within the wireless range of the AP 102 to “associate” or re-associate with the AP 102 to establish or maintain a corresponding communication link 108 (hereinafter also referred to as a “Wi-Fi link”) with the AP 102. For example, the beacon may include: an identification of a primary channel used by the corresponding AP 102 and a timing synchronization function for establishing or maintaining timing synchronization with the AP 102. The AP 102 may provide access to external networks to various STAs 104 in the WLAN via corresponding communication links 108 .

[0043] To establish a communication link 108 with the AP 102, each STA 104 is configured to perform passive or active scanning operations ("scanning") on frequency channels in one or more frequency bands (eg, 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz bands). To perform a passive scan, the STA 104 listens for beacons transmitted by the corresponding AP 102 at periodic time intervals, referred to as target beacon transmission times (TBTTs), measured in time units (TUs), where one TU may be equal to 1024 microseconds (μs). To perform an active scan, the STA 104 generates probe requests and sequentially transmits these probe requests on each channel to be scanned, and listens for probe responses from the AP 102. Each STA 104 may be configured to identify or select an AP 102 to associate with based on the scan information obtained through passive or active scanning, and perform authentication and association operations to establish a communication link 108 with the selected AP 102. The AP 102 assigns an association identifier (AID) to the STA 104 at the end of the association operation, and the AP 102 uses the AID to track the STA 104.

[0044] As wireless networks become more and more common, STA 104 may have the opportunity to select one of many BSSs within the range of the STA or to select among multiple APs 102 that together form an extended service set (ESS) (including multiple connected BSSs). The extended network station associated with WLAN 100 may be connected to a wired or wireless distribution system that allows multiple APs 102 to be connected in such an ESS. In this way, STA 104 may be covered by more than one AP 102 and may be associated with different APs 102 at different times for different transmissions. Additionally, after associating with AP 102, STA 104 may also be configured to periodically scan its surroundings to find a more suitable AP 102 to associate with. For example, a STA 104 that is moving relative to its associated AP 102 may perform a "roaming" scan to find another AP 102 with more suitable network characteristics (such as a larger received signal strength indicator (RSSI) or a reduced traffic load).

[0045] In some cases, STA 104 may form a network without AP 102 or other equipment other than STA 104 itself. An example of such a network is an ad hoc network (or wireless ad hoc network). Ad hoc networks may alternatively be referred to as mesh networks or peer-to-peer (P2P) networks. In some cases, ad hoc networks may be implemented within a larger wireless network (such as WLAN 100). In such implementations, although STA 104 may be able to communicate with each other via AP 102 using communication link 108, STA 104 may also communicate directly with each other via direct wireless link 110. In addition, two STA 104 may communicate via direct communication link 110, regardless of whether the two STA 104 are associated with the same AP 102 and served by the same AP 102. In such an ad hoc system, one or more STA 104 may assume the role played by AP 102 in the BSS. Such STA 104 may be referred to as a group owner (GO) and may coordinate transmission within the ad hoc network. Examples of direct wireless link 110 include a Wi-Fi Direct connection, a connection established by using a Wi-Fi Tunneled Direct Link Setup (TDLS) link, and other P2P group connections.

[0046] The AP 102 and the STA 104 may function and communicate (via corresponding communication links 108) in accordance with the IEEE 802.11 family of wireless communication protocol standards, such as those defined by the IEEE 802.11-2016 specification or its revisions, including, but not limited to, 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be. These standards define WLAN radio and baseband protocols for the PHY and media access control (MAC) layers. The AP 102 and the STA 104 transmit and receive wireless communications (hereinafter also referred to as "Wi-Fi communications") to and from each other in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs). The AP 102 and STA 104 in the WLAN 100 may transmit PPDUs on an unlicensed spectrum, which may be a portion of a spectrum that includes frequency bands traditionally used by Wi-Fi technology, such as the 2.4 GHz band, the 5 GHz band, the 60 GHz band, the 3.6 GHz band, and the 900 MHz band. Some implementations of the AP 102 and STA 104 described herein may also communicate in other frequency bands, such as the 6 GHz band, that may support both licensed and unlicensed communications. The AP 102 and STA 104 may also be configured to communicate on other frequency bands, such as shared licensed frequency bands, where multiple operators may have licenses to operate in one or more of the same or overlapping frequency bands.

[0047] Each frequency band may include multiple channels (which may be used as subchannels of a larger bandwidth channel as described below). For example, PPDUs compliant with IEEE 802.11n, 802.11ac, and 802.11ax standard revisions may be transmitted on 2.4 GHz and 5 GHz frequency bands, where each frequency band is divided into multiple 20 MHz channels. As such, these PPDUs are transmitted on a physical channel with a minimum bandwidth of 20 MHz, but may be formed into larger channels through channel bonding. For example, a PPDU may be transmitted on a physical channel with a bandwidth of 40 MHz, 80 MHz, 160 MHz, or 320 MHz by bonding multiple 20 MHz channels (which may be referred to as subchannels) together.

[0048] Each PPDU is a composite structure including a PHY preamble and a payload in the form of a PLCP service data unit (PSDU). The information provided in the preamble can be used by the receiving device to decode subsequent data in the PSDU. In an instance where the PPDU is transmitted over a bonded channel, the preamble field can be copied and transmitted in each of a plurality of component channels. The PHY preamble may include both a first part (or "legacy preamble") and a second part (or "non-legacy preamble"). The first part can be used for packet detection, automatic gain control and channel estimation, and other purposes. The first part can also be used to maintain compatibility with legacy devices and non-legacy devices. The format, decoding, and information provided therein of the second part of the preamble are based on the specific IEEE 802.11 protocol to be used to transmit the payload.

[0049] Figure 2 An example protocol data unit (PDU) 200 that can be used for wireless communication between an AP and a number of STAs is shown. For example, the PDU 200 can be configured as a PPDU. As shown, the PDU 200 includes a PHY preamble 201 and a PHY payload 204. For example, the preamble 201 can include a first portion 202, which itself includes a legacy short training field (L-STF) 206 that can be composed of two BPSK symbols, a legacy long training field (L-LTF) 208 that can be composed of two BPSK symbols, and a legacy signal field (L-SIG) 210 that can be composed of one BPSK symbol. The first portion 202 of the preamble 201 can be configured according to the IEEE 802.11a wireless communication protocol standard. The preamble 201 may also include a second portion 203 including one or more non-legacy signal fields 212 , for example, compliant with an IEEE wireless communication protocol such as IEEE 802.11ac, 802.11ax, 802.11be, or a later wireless communication protocol standard.

[0050] L-STF 206 generally enables the receiving device to perform automatic gain control (AGC) and coarse timing and frequency estimation. L-LTF 208 generally enables the receiving device to perform fine timing and frequency estimation, and can also perform initial estimation of the wireless channel. L-SIG 210 generally enables the receiving device to determine the duration of the PDU and use the determined duration to avoid transmitting on the PDU. For example, L-STF 206, L-LTF 208 and L-SIG 210 can be modulated according to a binary phase shift keying (BPSK) modulation scheme. Payload 204 can be modulated according to a BPSK modulation scheme, an orthogonal BPSK (Q-BPSK) modulation scheme, an orthogonal amplitude modulation (QAM) modulation scheme, or another appropriate modulation scheme. Payload 204 may include a PSDU including a data field (DATA) 214, which in turn may carry, for example, a higher layer data in the form of a media access control (MAC) protocol data unit (MPDU) or an aggregated MPDU (A-MPDU).

[0051] Figure 2 Also shown is an example L-SIG 210 in the PDU 200. The L-SIG 210 includes a data rate field 222, reserved bits 224, a length field 226, parity bits 228, and a tail field 230. The data rate field 222 indicates the data rate (note that the data rate indicated in the data rate field 212 may not be the actual data rate of the data carried in the payload 204). The length field 226 indicates the packet length, for example, in units of symbols or bytes. The parity bits 228 may be used to detect bit errors. The tail field 230 includes tail bits, which may be used by a receiving device to terminate the operation of a decoder (e.g., a Viterbi decoder). The receiving device may use the data rate and length indicated in the data rate field 222 and the length field 226 to determine the packet duration, for example, in microseconds (μs) or other time units.

[0052] Figure 3AAnother example PDU 300 that can be used for wireless communication between an AP and a number of STAs is shown. The PDU 300 can be used for MU-OFDMA or MU-MIMO transmission. The PDU 300 includes a PHY preamble, which includes a first part 302 and a second part 304. The PDU 300 may further include a PHY payload 306 after the preamble (e.g., in the form of a PSDU including a data field 324). The first part 302 includes an L-STF 308, an L-LTF 310, and an L-SIG 312. According to the IEEE 802.11ax revision to the IEEE 802.11 wireless communication protocol standard, the second part 304 of the preamble and the data field 324 may be formatted as a high efficiency (HE) WLAN preamble and a frame, respectively. The second portion 304 includes a repeating legacy signal field (RL-SIG) 314, a first HE signal field (HE-SIG-A) 316, a second HE signal field (HE-SIG-B) 316 encoded separately from the HE-SIG-A 318, a HE short training field (HE-STF) 320, and a number of HE long training fields (HE-LTF) 322. As with the L-STF 308, L-LTF 310, and L-SIG 312, in instances involving the use of bonded channels, the information in the RL-SIG 314 and HE-SIG-A 316 may be replicated and transmitted in each component 20 MHz subchannel. In contrast, the HE-SIG-B 318 may be unique to each 20 MHz subchannel and may be targeted to a specific STA 104.

[0053] The RL-SIG 314 may indicate to the HE-compatible STA 104 that the PPDU is a HE PPDU. The AP 102 may use the HE-SIG-A 316 to identify multiple STAs 104 and inform the multiple STAs 104 that the AP has scheduled UL or DL ​​resources for them. The HE-SIG-A 316 may be decoded by each HE-compatible STA 104 served by the AP 102. The HE-SIG-A 316 includes information that may be used by each identified STA 104 to decode the associated HE-SIG-B 318. For example, the HE-SIG-A 316 may indicate the frame format (including the location and length of the HE-SIG-B 318), the available channel bandwidth, and the modulation and coding scheme (MCS), etc. The HE-SIG-A 316 may also include HE WLAN signaling information that may be used by STAs 104 other than the identified STAs 104.

[0054] HE-SIG-B 318 may carry STA-specific scheduling information, such as, for example, per-user MCS values ​​and per-user RU allocation information. In the context of DL MU-OFDMA, such information enables the corresponding STA 104 to identify and decode the corresponding RU in the associated data field. Each HE-SIG-B 318 includes a common field and at least one field that varies from STA to STA ("user-specific"). The common field may indicate the RU distribution to multiple STAs 104, indicate the RU assignment in the frequency domain, indicate which RUs are allocated for MU-MIMO transmission and which RUs correspond to MU-OFDMA transmission, and the number of users in the allocation, etc. The common field may be encoded with common bits, CRC bits, and tail bits. The user-specific fields are assigned to a specific STA 104 and may be used to schedule a specific RU and indicate the schedule to other WLAN devices. Each user-specific field may include multiple user block fields (which may be followed by padding). Each user block field may include two user fields containing information for two corresponding STAs to decode their corresponding RU payloads in the data field 324 .

[0055] Figure 3B Another example PHY preamble that may be used for communication between an AP and each of a number of stations is shown. PPDU 350 may be used for SU, MU-OFDMA, or MU-MIMO transmissions. PPDU 350 includes a PHY preamble that includes a legacy portion 352 and a non-legacy portion 354. PPDU 350 may further include a PHY payload 356 (e.g., in the form of a PSDU including a data field 376) following the preamble. Legacy portion 352 includes L-STF 358, L-LTF 360, and L-SIG 362. The non-legacy portion 354 of the preamble and the data field 376 may be formatted as an extremely high throughput (EHT) WLAN preamble and frame, respectively, in accordance with the IEEE 802.11be revision to the IEEE 802.11 wireless communication protocol standard, or may be formatted as a preamble and frame, respectively, compliant with any later (post-HE) version of a new wireless communication protocol (compliant with a future IEEE 802.11 wireless communication protocol standard or other standard).

[0056] The non-legacy portion 354 of the preamble includes a second signal field (referred to herein as “Pre-SIG”) 366, a third signal field (referred to herein as “EHT-SIG-A”, although it may also be constructed as other wireless communication protocol versions other than EHT and carry version-related information about other wireless communication protocol versions other than EHT) 368, and a fourth signal field (referred to herein as “EHT-SIG-B”, although it may also be constructed as other wireless communication protocol versions other than EHT and carry version-related information about other wireless communication protocol versions other than EHT) 370. The non-legacy portion 354 further includes an additional short training field 372 (referred to herein as “EHT-STF”, although it may also be constructed as other wireless communication protocol versions other than EHT and carry version-related information about other wireless communication protocol versions other than EHT) and several additional long training fields (referred to herein as “EHT-LTF”, although they may also be constructed as other wireless communication protocol versions other than EHT and carry version-related information about other wireless communication protocol versions other than EHT) 374. As with the L-STF 358, L-LTF 360, and L-SIG 362, in instances involving the use of bonded channels, the information in the Pre-SIG 366 and EHT-SIG-A 368 may be replicated and transmitted in each component 20 MHz channel. In some implementations, the EHT-SIG-A 368 may additionally or alternatively carry information in one or more non-primary 20 MHz channels that is different from the information carried in the primary 20 MHz channel. The HE-SIG-B 370 may be unique for each 20 MHz channel and, as described above, may be targeted to a specific STA 104. The non-legacy portion 354 of the preamble may or may not include a repeated legacy signal field (RL-SIG) 364 after the L-SIG 362 and before the Pre-SIG 366.

[0057] The EHT-SIG-A 368 may include one or more jointly encoded symbols and may be encoded in a different block than the block in which the Pre-SIG 366 is encoded. The EHT-SIG-A 368 may be used by the AP to identify multiple STAs 104 and to inform the multiple STAs 104 that the AP has scheduled UL or DL ​​resources. The EHT-SIG-A 368 may be decoded by each compatible STA 104 served by the AP 102. The EHT-SIG-A 368 includes information that may be used by the identified STA 104 to decode the associated EHT-SIG-B 370. The EHT-SIG-A 368 may generally be used by a receiving device to interpret the bits in the EHT-SIG-B 370 or the data field 376. For example, the EHT-SIG-A 368 may indicate the location and length of the EHT-SIG-B 370 in each component channel, the available channel bandwidth, and the modulation and coding scheme (MCS), among other things. The EHT-SIG-A 368 may further include a cyclic redundancy check (CRC) (eg, 4 bits) and a tail (eg, 6 bits) that may be used for a binary convolutional code (BCC).

[0058] The EHT-SIG-B 370 may include multiple symbols that may be encoded in a different block than the block in which the EHT-SIG-A 368 is encoded. In some other implementations, the EHT-SIG-A 368 may be jointly encoded with some or all of the EHT-SIG-B 370. For example, the EHT-SIG-A 368 may be jointly encoded with a first portion of the EHT-SIG-B 370 that includes information common to all users served by the PPDU 350. The EHT-SIG-B 370 may carry STA-specific scheduling information such as, for example, per-user MCS values ​​and per-user RU allocation information. The EHT-SIG-B 370 may generally be used by a receiving device to interpret the bits in the data field 376. In the context of DL MU-OFDMA, such information enables the corresponding STA 104 to identify and decode the corresponding RU in the associated data field 376. Each EHT-SIG-B 370 includes a common field and at least one field that is specific to a STA ("user-specific"). The common field may indicate the RU distribution to multiple STAs 104, indicate the RU assignment in the frequency domain, indicate which RUs are allocated for MU-MIMO transmission and which RUs correspond to MU-OFDMA transmission, and the number of users in the allocation, etc. The common field may be encoded with common bits, CRC bits, and tail bits. The user-specific fields are assigned to a specific STA 104 and may be used to schedule a specific RU and indicate the scheduling to other WLAN devices. Each user-specific field may include multiple user block fields (which may be followed by padding). Each user block field may include, for example, two user fields, which contain information for two corresponding STAs to decode their corresponding RU payloads.

[0059] The Pre-SIG 366 and the RL-SIG 364, if present, may indicate to the STA 104 that is compatible with EHT or a later version that the PPDU 350 is an EHT PPDU or a PPDU that complies with another non-legacy wireless communication protocol version. For example, the Pre-SIG 366 may be used by the receiving device to interpret bits in one or more of the EHT-SIG-A 368, the EHT-SIG-B 370, or the data field 376. In some implementations, the Pre-SIG 366 may include a reserved bit that indicates whether the PPDU 350 complies with, for example, EHT or a later version of the IEEE 802.11 wireless communication protocol standard family or other standards (e.g., after IEEE 802.11ax). In some implementations, the Pre-SIG 366 includes a version field that includes at least one bit that indicates a specific wireless communication protocol version that the PPDU 350 complies with.

[0060] Figure 4 An example PPDU 400 is shown that may be used for communication between an AP 102 and a number of STAs 104. As described above, each PPDU 400 includes a PHY preamble 402 and a PSDU 404. Each PSDU 404 may carry one or more MAC protocol data units (MPDUs). For example, each PSDU 404 may carry an aggregated MPDU (A-MPDU) 408 that includes an aggregation of multiple A-MPDU subframes 406. Each A-MPDU subframe 406 may include a MAC delimiter 410 and a MAC header 412 preceding an accompanying MPDU 414 that includes a data portion (“payload” or “frame body”) of the A-MPDU subframe 406. The MPDU 414 may carry one or more MAC service data unit (MSDU) subframes 416. For example, the MPDU 414 may carry an aggregated MSDU (A-MSDU) 418 that includes multiple MSDU subframes 416. Each MSDU subframe 416 includes a corresponding MSDU 420 followed by a subframe header 422 .

[0061] Referring back to the A-MPDU subframe 406, the MAC header 412 may include: several fields containing information defining or indicating characteristics or attributes of the data encapsulated in the frame body 414. The MAC header 412 also includes several fields indicating the address of the data encapsulated in the frame body 414. For example, the MAC header 412 may include a combination of a source address, a transmitter address, a receiver address, or a destination address. The MAC header 412 may include: a frame control field containing control information. The frame control field specifies the frame type, for example, a data frame, a control frame, or a management frame. The MAC header 412 may further include a duration field, which indicates the duration from the end of the PPDU until the end of the acknowledgment (ACK) of the last PPDU to be transmitted by the wireless communication device (for example, a block ACK (BA) in the case of an A-MPDU). The use duration field is used to reserve the wireless medium for the indicated duration, thereby establishing a NAV. Each A-MPDU subframe 406 may also include a frame check sequence (FCS) field 424 for error detection. For example, the FCS field 416 may include a cyclic redundancy check (CRC).

[0062] As described above, the AP 102 and the STA 104 may support multi-user (MU) communications; that is, concurrent transmissions from one device to each of multiple devices (e.g., multiple simultaneous downlink (DL) communications from the AP 102 to the corresponding STAs 104), or concurrent transmissions from multiple devices to a single device (e.g., multiple simultaneous uplink (UL) transmissions from the corresponding STAs 104 to the AP 102). To support MU transmissions, the AP 102 and the STA 104 may utilize multi-user multiple-input multiple-output (MU-MIMO) and multi-user orthogonal frequency division multiple access (MU-OFDMA) techniques.

[0063] In the MU-OFDMA scheme, the available spectrum of a wireless channel may be divided into multiple resource units (RUs), each of which includes several different frequency subcarriers ("tones"). Different RUs may be allocated or assigned to different STAs 104 by AP 102 at a specific time. The size and distribution of RUs may be referred to as RU allocation. In some implementations, RUs may be allocated in 2MHz intervals, and thus, the minimum RU may include 26 tones including 24 data tones and 2 pilot tones. Therefore, in a 20MHz channel, up to 9 RUs (such as 2MHz, 26 tones RU) may be allocated (because some tones are reserved for other purposes). Similarly, in a 160MHz channel, up to 74 RUs may be allocated. Larger RUs of 52 tones, 106 tones, 242 tones, 484 tones, and 996 tones may also be allocated. Adjacent RUs may be separated by a null subcarrier, such as a DC subcarrier, for example, to reduce interference between adjacent RUs, reduce receive-side DC offset, and avoid transmit center frequency leakage.

[0064] For UL MU transmissions, the AP 102 may transmit a trigger frame to initiate and synchronize UL MU-OFDMA or UL MU-MIMO transmissions from multiple STAs 104 to the AP 102. Such a trigger frame may thereby enable multiple STAs 104 to send UL traffic concurrently in time to the AP 102. The trigger frame may address one or more STAs 104 by a corresponding association identifier (AID), and may assign one or more RUs to each AID (and thus each STA 104) that may be used to send UL traffic to the AP 102. The AP may also specify one or more random access (RA) RUs that unscheduled STAs 104 may contend for.

[0065] APs and STAs that include multiple antennas can support various diversity schemes. For example, spatial diversity can be used by one or both of the transmitting device or the receiving device to improve the robustness of the transmission. For example, in order to implement a transmit diversity scheme, the transmitting device can redundantly transmit the same data on two or more antennas. APs and STAs that include multiple antennas can also support space-time block coding (STBC). Using STBC, the transmitting device also transmits multiple copies of the data stream across several antennas to increase the possibility of decoding the correct data using various received versions of the data. More specifically, the data stream to be transmitted is encoded in blocks that are distributed between spaced-apart antennas and across time. In general, when the number of transmitting antennas N is greater than 1,000,000, the number of receiving antennas N is greater than 1,000,000. Tx Exceeding the number of spatial streams N SS When N is used, STBC (described below) can be used. ss A spatial stream can be mapped into several (N STS ) space-time streams, which are then mapped to N Tx A transmission chain.

[0066] APs and STAs that include multiple antennas may also support spatial multiplexing, which may be used to increase spectral efficiency and the resulting throughput of the transmission. To achieve spatial multiplexing, the transmitting device divides the data stream into a number (N ss These spatial streams are then encoded separately and transmitted through multiple (N Tx If the transmitting device includes N Tx The receiving device includes N transmitting antennas and Rx receive antennas, the maximum number of spatial streams that the transmitting device can simultaneously transmit to the receiving device is N ss Limited by N Tx and N Rx In some implementations, the AP 102 and the STA 104 may be able to implement both transmit diversity and spatial multiplexing. For example, in the number of spatial streams (N ss ) is less than the number of transmitting antennas (N Tx ), the spatial streams may be multiplied by a spatial spreading matrix to achieve transmit diversity.

[0067] APs and STAs that include multiple antennas may also support beamforming. Beamforming refers to focusing the energy of a transmission in the direction of a target receiver. Beamforming can be used both in a single-user context, for example to improve the signal-to-noise ratio (SNR), and in a multi-user (MU) context, for example to implement MU multiple-input multiple-output (MIMO) (MU-MIMO) transmission (also known as spatial division multiple access (SDMA)). To perform beamforming, a transmitting device (referred to as a beamforming initiator) transmits a signal from each of the multiple antennas. The beamforming initiator configures the amplitude and phase shift between the signals transmitted from different antennas so that the signals add constructively in a specific direction toward the intended receiver (which is referred to as a beamforming receiver). The manner in which the beamforming initiator configures the amplitude and phase shift depends on the channel state information (CSI) associated with the wireless channel over which the beamforming initiator intends to communicate with the beamforming receiver.

[0068] In order to obtain the CSI required for beamforming, the beamforming initiator may perform a channel sounding procedure with the beamforming receiver. For example, the beamforming initiator may transmit one or more sounding signals (e.g., in the form of null data packets (NDPs)) to the beamforming receiver. The beamforming receiver may then perform channel sounding procedures for N channels corresponding to all transmit antennas and receive antennas based on the sounding signals. Tx x N Rx The beamformer performs measurements for each of the subchannels. The beamformee generates a feedback matrix based on the channel measurements and typically compresses the feedback matrix before transmitting the feedback to the beamformer initiator. The beamformer initiator can then generate a precoding (or "steering") matrix for the beamformee based on the feedback and use the steering matrix to precode the data stream to configure the amplitude and phase shift for subsequent transmission to the beamformee.

[0069] As described above, the transmitting device may support the use of a diversity scheme. When beamforming is performed, the transmitted beamforming array gain is proportional to N Tx and N SS Thus, when beamforming is performed to increase gain, the number of transmit antennas N is increased within other constraints. Tx This is generally desirable. It is also possible to steer the transmission more accurately by increasing the number of transmit antennas. This is particularly advantageous in the context of MU transmissions where reducing inter-user interference is particularly important.

[0070] Figure 5 1 shows a block diagram of an example wireless communication device 500. In some implementations, the wireless communication device 500 may be a wireless communication device for a STA (such as the one described above with reference to FIG. Figure 1In some implementations, the wireless communication device 500 may be an example of a device in an AP (such as one of the STAs 104 described above). Figure 1 The wireless communication device 500 is an example of a device in the AP 102 described herein. The wireless communication device 500 is capable of transmitting (or outputting for transmission) and receiving wireless communications (e.g., in the form of wireless packets). For example, the wireless communication device may be configured to transmit and receive packets in the form of PPDUs and MPDUs that comply with the IEEE 802.11 standard (such as the standard defined by the IEEE 802.11-2016 specification or its amendments, including but not limited to 802.11ah, 802.11ad, 802.11ay, 802.11ax, 802.11az, 802.11ba, and 802.11be).

[0071] The wireless communication device 500 may be or may include a chip, system on chip (SoC), chipset, package, or device including one or more modems 502 (e.g., Wi-Fi (IEEE 802.11 compliant) modems). In some implementations, the one or more modems 502 (collectively, "modems 502") additionally include a WWAN modem (e.g., a 3GPP 4G LTE or 5G compatible modem). In some implementations, the wireless communication device 500 also includes one or more radios 504 (collectively, "radios 504"). In some implementations, the wireless communication device 506 further includes one or more processors, processing blocks, or processing elements 506 (collectively, "processors 506") and one or more memory blocks or elements 508 (collectively, "memory 508").

[0072] The modem 502 may include an intelligent hardware block or device (for example, such as an application specific integrated circuit (ASIC)). The modem 502 is generally configured to implement the PHY layer. For example, the modem 502 is configured to modulate packets and output the modulated packets to the radio 504 for transmission on the wireless medium. Similarly, the modem 502 is configured to obtain modulated packets received by the radio 504 and demodulate the packets to provide demodulated packets. In addition to the modulator and demodulator, the modem 502 may further include a digital signal processing (DSP) circuit system, an automatic gain control (AGC), an encoder, a decoder, a multiplexer, and a demultiplexer. For example, when in the transmission mode, the data obtained from the processor 506 is provided to the encoder, which encodes the data to provide coded bits. The coded bits are then mapped to points in the modulation constellation (using the selected MCS) to provide modulated symbols. Subsequently, the modulated symbols may be mapped to a number (N SS ) spatial streams or several (N STSThe modulated symbols in the corresponding spatial stream or space-time stream may then be multiplexed, transformed via an inverse fast Fourier transform (IFFT) block, and then provided to the DSP circuitry for Tx windowing and filtering. The digital signal may then be provided to a digital-to-analog converter (DAC). The resulting analog signal may then be provided to an upconverter and ultimately to the radio 504. In an implementation involving beamforming, the modulated symbols in the corresponding spatial stream may be precoded via a steering matrix before being provided to the IFFT block.

[0073] When in receive mode, a digital signal received from the radio 504 is provided to a DSP circuit system that is configured to acquire the received signal, for example, by detecting the presence of the signal and estimating the initial timing and frequency offset. The DSP circuit system is further configured to digitally condition the digital signal, for example, using channel (narrowband) filtering, analog impairment conditioning (such as correcting I / Q imbalance), and applying digital gain to ultimately acquire a narrowband signal. Subsequently, the output of the DSP circuit system may be fed to an AGC that is configured to use information extracted from the digital signal (e.g., in one or more received training fields) to determine an appropriate gain. The output of the DSP circuit system is also coupled to a demodulator that is configured to extract modulated symbols from the signal and, for example, calculate a log-likelihood ratio (LLR) for each bit position of each subcarrier in each spatial stream. The demodulator is coupled to a decoder that may be configured to process the LLRs to provide decoded bits. Subsequently, the decoded bits from all spatial streams are fed to a demultiplexer for demultiplexing. The demultiplexed bits may then be descrambled and provided to the MAC layer (processor 506) for processing, evaluation, or interpretation.

[0074] The radio 504 generally includes at least one radio frequency (RF) transmitter (or "transmitter chain") and at least one RF receiver (or "receiver chain"), which can be combined into one or more transceivers. For example, the RF transmitter and receiver may include various DSP circuit systems, including at least one power amplifier (PA) and at least one low noise amplifier (LNA), respectively. The RF transmitter and receiver may in turn be coupled to one or more antennas. For example, in some implementations, the wireless communication device 500 may include or be coupled to multiple transmit antennas (each having a corresponding transmit chain) and multiple receive antennas (each having a corresponding receive chain). The codewords output from the modem 502 are provided to the radio 504, which then transmits the codewords via the coupled antenna. Similarly, the codewords received via the antenna are obtained by the radio 504, which then provides the codewords to the modem 502.

[0075] The processor 506 may include an intelligent hardware block or device designed to perform the functions described herein, such as, for example, a processing core, a processing block, a central processing unit (CPU), a microprocessor, a microcontroller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a programmable logic device (PLD) (such as a field programmable gate array (FPGA)), discrete gate or transistor logic, discrete hardware components, or any combination thereof. The processor 506 processes information received through the radio 504 and the modem 502, and processes information to be output by the modem 502 and the radio 504 for transmission over a wireless medium. For example, the processor 506 may implement a control plane and a MAC layer, which is configured to perform various operations related to the generation and transmission of MPDUs, frames, or packets. The MAC layer is configured to perform or facilitate encoding and decoding of frames, spatial multiplexing, space-time block coding (STBC), beamforming, and OFDMA resource allocation, and other operations or techniques. In some implementations, the processor 506 may generally control the modem 502 so that the modem performs the various operations described above.

[0076] The memory 504 may include a tangible storage medium, such as a random access memory (RAM) or a read-only memory (ROM) or a combination thereof. The memory 504 may also store non-transient processor or computer executable software (SW) code containing instructions that, when executed by the processor 506, cause the processor to perform various operations for wireless communication described herein, including generation, transmission, reception, and interpretation of MPDUs, frames, or packets. For example, the various functions of the various components disclosed herein or the various blocks or steps of the methods, operations, processes, or algorithms disclosed herein may be implemented as one or more modules of one or more computer programs.

[0077] Fig. 6A 602 is a block diagram of an example AP 602. For example, the AP 602 may be a reference Figure 1 An example implementation of AP 102 is described. AP 602 includes a wireless communication device (WCD) 610. For example, wireless communication device 610 may be a wireless communication device (WCD) 610. Figure 5An example implementation of the wireless communication device 500 described. The AP 602 also includes a plurality of antennas 620 coupled to the wireless communication device 610 to transmit and receive wireless communications. In some implementations, the AP 602 additionally includes an application processor 630 coupled to the wireless communication device 610, and a memory 640 coupled to the application processor 630. The AP 602 further includes at least one external network interface 650, which enables the AP 602 to communicate with a core network or a backhaul network to obtain access to an external network including the Internet. For example, the external network interface 650 may include one or both of a wired (e.g., Ethernet) network interface and a wireless network interface (such as a WWAN interface). Components of the aforementioned components may communicate directly or indirectly with other components of these components on at least one bus. The AP 602 further includes a housing that encloses the wireless communication device 610, the application processor 630, the memory 640, and encloses at least a portion of the antenna 620 and the external network interface 650.

[0078] Figure 6B 604. For example, STA 604 may be a reference Figure 1 104. The STA 604 includes a wireless communication device 615. For example, the wireless communication device 615 may be a reference Figure 5 An example implementation of the wireless communication device 500 described. The STA 604 also includes one or more antennas 625 coupled to the wireless communication device 615 to transmit and receive wireless communications. The STA 604 additionally includes an application processor 635 coupled to the wireless communication device 615, and a memory 645 coupled to the application processor 635. In some implementations, the STA 604 further includes a user interface (UI) 655 (such as a touch screen or keyboard) and a display 665, which can be integrated with the UI 655 to form a touch screen display. In some implementations, the STA 604 may further include one or more sensors 675 (such as one or more inertial sensors, accelerometers, temperature sensors, pressure sensors, or altitude sensors, for example). Components of the aforementioned components can communicate directly or indirectly with other components of these components on at least one bus. The STA 604 further includes a housing that encloses the wireless communication device 615, the application processor 635, the memory 645, and at least portions of the antenna 625, the UI 655, and the display 665.

[0079] As described above, link adaptation is a technique for adapting modulation, coding or other signaling parameters to channel conditions on a wireless medium. According to some link adaptation techniques, a transmitting device transmits a sounding packet to a receiving device, and the receiving device feeds back CSI to the transmitting device. The transmitting device then selects the MCS to be used for subsequent data transmission to the receiving device based on the received CSI. MCS defines a set of modulation and coding parameters to be used when transmitting signals on a wireless channel. Example parameters include code rate, modulation type, and the number of spatial streams. Example modulation types include, but are not limited to, binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), and M-quadrature amplitude modulation (M-QAM). The modulation order describes the number of different or unique symbols that can be transmitted using a given modulation type. For example, BPSK has a modulation order of 2, QPSK has a modulation order of 4, and M-QAM may have various modulation orders (depending on the value of M).

[0080] In some implementations, the receiving device may generate CSI by measuring the signal to interference plus noise ratio (SINR) of the wireless channel based on the received sounding packet. SINR may be averaged over the bandwidth of the wireless channel at any suitable granularity level (such as per bandwidth, per subband, per RU, per RU group, or per frequency modulation). Various aspects of the present disclosure recognize that under the same channel conditions, different modulation types tend to produce different SINRs. However, the linear average SINR does not indicate how the link will perform for a given modulation type. In addition, the reported SINR is based on the transmitter configuration (such as the number of spatial streams) and the receiver type (such as MMSE or ML) implemented by the transmitting device and the receiving device respectively when the sounding packet is transmitted. However, the transmitter configuration or receiver type used to transmit and receive the sounding packet may be different from the transmitter configuration or receiver type used for subsequent communications between the transmitting device and the receiving device.

[0081] Various aspects generally relate to link adaptation in wireless communication systems, and more particularly to transmitter-based modulation and coding scheme (MCS) selection. In some aspects, a transmitting device may transmit a test packet (such as a sounding packet) to a receiving device on a wireless channel. The receiving device may generate multiple signal-to-interference-plus-noise ratio (SINR) estimates for the wireless channel based on the received test packet. In some aspects, each SINR estimate may be associated with a specific corresponding modulation order selected from a set of multiple possible modulation orders (such as BPSK, QPSK, or M-QAM). In some other aspects, each SINR estimate may be generated based on a transmitter configuration (such as the number of spatial streams) or a receiver type (such as MMSE or ML) to be used for subsequent communications by the transmitting device and the receiving device, respectively. The receiving device may then transmit feedback to the transmitting device, the feedback including at least one of the SINR estimates associated with the specific corresponding modulation order. In some implementations, the receiving device may transmit multiple or all of the SINR estimates to the transmitting device. The transmitting device may then select an MCS to be used for subsequent communications with the receiving device based on the one or more SINR estimates and the corresponding modulation order.

[0082] Specific implementations of the subject matter described in the present disclosure may be implemented to achieve one or more of the following potential advantages. In some implementations, the described techniques may be used to increase the data rate and throughput of communications on wireless channels. By determining the modulation order associated with each SINR estimate reported by the receiving device, the transmitting device may make a more informed MCS selection based on the current channel conditions. For example, the transmitting device may select the MCS that produces the maximum throughput for the current channel conditions based on the reported SINR estimate and the associated modulation order. In addition, by adjusting the SINR estimate based on the transmitter configuration or receiver type to be used for subsequent communications (rather than just when the channel is sounded), the receiving device can ensure that the reported SINR estimate is relevant to the data transmission they are intended to carry out. Accordingly, various aspects of the present disclosure enable the transmitting device to select an MCS that is more closely customized for the channel conditions and device configuration when transmitting data to the receiving device.

[0083] Figure 7 A sequence diagram illustrating an example message exchange 700 between a transmitting (TX) device 710 and a receiving (RX) device (RX device) 720 over a wireless channel 730 is shown according to some implementations. In some implementations, the TX device 710 may be Figure 1 AP 102 or Fig. 6A In some other implementations, the TX device 710 may be Figure 1 STA 104 or Figure 6BIn some implementations, the RX device 720 may be an example of any of the STAs 604. Figure 1 AP 102 or Fig. 6A In some other implementations, the RX device 720 may be Figure 1 STA 104 or Figure 6B An example of any one of STA 604.

[0084] The TX device 710 determines a future transmitter (TX) configuration that will be used to transmit wireless signals to the RX device 720 after the transmission of the test packet. The TX configuration may include the number of spatial streams (N) on which data will be transmitted. SS ). Aspects of the present disclosure recognize that the TX configuration may affect the channel estimation performed by the RX device 720. For example, if the TX device 710 transmits a test packet on 4 spatial streams, but only 2 spatial streams are used for subsequent data transmission to the RX device 720, the CSI reported back for the 4 spatial streams may not accurately describe the wireless channel for 2-stream communication. In some implementations, the TX device 710 may use a future TX configuration to transmit the test packet to the RX device 720. For example, the TX device 710 may use the same number of spatial streams (N) that will be used for subsequent data transmission to the RX device 720. SS ) to transmit the test packet. In some aspects, the test packet may be a sounding packet (such as, for example, a null data packet (NDP)).

[0085] The RX device 720 determines a future receiver (RX) type that will be used to receive wireless signals from the TX device 710 after reception of the test packet. The RX type may include a minimum mean square error (MMSE) receiver type or a maximum likelihood ratio (ML) receiver type. The RX type implemented by the RX device 720 at any given time may be regulated by a state machine. The RX device 720 receives the test packet from the TX device 710 and generates feedback for the wireless channel 730 based at least in part on the received test packet. In some aspects, the feedback may include channel state information (CSI) associated with the wireless channel 730. For example, the RX device 720 may determine characteristics of the wireless channel 730 (referred to as "channel estimation") based on one or more training fields (such as LTFs) included in the PHY preamble of the test packet.

[0086] In some implementations, the RX device 720 may generate one or more SINR estimates for the wireless channel 730. More specifically, each SINR estimate may be associated with a specific modulation order. For example, the RX device 720 may calculate a per-tone SINR for the wireless channel 730 based on the channel estimate. The per-tone SINR is a measurement of the received signal strength, channel gain, interference, and noise on each tone (frequency subcarrier) of the wireless channel 730. The RX device 720 may then convert the per-tone SINR into a per-tone channel capacity. Note that channel capacity generally increases with increasing SINR. However, since the maximum achievable data rate for any wireless communication is bounded by the modulation order, the channel capacity will be saturated when the SINR exceeds a certain threshold. Thus, each modulation order will have a different constrained capacity curve. By taking a linear average of the per-tone channel capacity and mapping the average capacity to each constrained capacity curve, the RX device 720 can determine the "effective" SINR for each modulation order. The effective SINR is the SINR that the RX device 720 estimates will be used for wireless transmissions for a given modulation order.

[0087] As described above, the RX type implemented by the RX device 720 can be managed by a state machine. In some examples, the RX type used to receive the test packet and estimate the SINR may be different from the RX type that the RX device 720 will use to receive subsequent transmissions from the TX device 710. Aspects of the present disclosure recognize that the RX type implemented by the RX device 720 may affect the SINR calculation. For example, if the RX device 720 uses an MMSE receiver type to receive the test packet and estimate the SINR, but will use an ML receiver type to receive subsequent data transmissions from the TX device 710, the SINR perceived by the RX device 720 when receiving the test packet may not accurately describe the SINR that the RX device 720 will perceive when receiving subsequent data transmissions. In some implementations, the RX device 720 may adjust the effective SNR value based at least in part on the future RX type. For example, the RX device 720 may predict or infer the SINR associated with the future RX type based on the SINR associated with the RX type used to receive the test packet.

[0088] The RX device 720 reports feedback back to the TX device 710, which includes one or more of the SINR estimates. The RX device 720 may further provide an indication of the modulation order associated with each SINR estimate reported back to the TX device 710. In some implementations, the RX device 720 may report a single SINR estimate back to the TX device 710. For example, the feedback may only include the SINR estimate that results in the highest throughput (referred to herein as the "optimal" SINR estimate) and information identifying the modulation order associated with the optimal SINR estimate. In some other implementations, the RX device 720 may report multiple SINR estimates back to the TX device 710. For example, the feedback may include an SINR estimate associated with each modulation order supported by the RX device 720. In some aspects, the feedback may include information identifying the modulation order associated with each SINR estimate. In some other aspects, the SINR estimates may be pre-arranged based on the modulation order they are associated with. For example, the SINR estimates may be arranged from the lowest to the highest (or from the highest to the lowest) modulation order. Accordingly, the feedback may not include any additional information identifying the modulation order associated with each SINR estimate.

[0089] The TX device 710 receives feedback from the RX device 720 and selects an MCS to be used for subsequent communications with the RX device 720 based at least in part on the SINR estimate(s) and the modulation order associated with each SINR estimate. For example, if the feedback includes only the best SINR estimate, the TX device 710 may select an MCS that follows the modulation order associated with the reported SINR estimate. Alternatively, if the feedback includes multiple SINR estimates, the TX device 710 may balance the effective SINR at the associated modulation order when selecting the MCS to achieve the highest throughput. For example, QPSK may be more robust to noise and interference than 16-QAM, but has lower spectral efficiency. In contrast, 16-QAM may have twice the spectral efficiency compared to QPSK, but may require more retransmissions on noisy channels.

[0090] The TX device 710 then transmits one or more packets (TX packets) to the RX device 720 using the selected MCS. As described above, the TX configuration (N SS ) can be used with the TX configuration (N SS ) are the same. Accordingly, the selected MCS may be optimal for the channel conditions, TX configuration, and RX type associated with the transmission and reception of the TX packet.

[0091] Figure 8800 between a transmitting (TX) device 810 and a receiving (RX) device 820 over a wireless channel 830 according to some implementations. In some implementations, the TX device 810 may be Figure 1 AP 102 or Fig. 6A In some other implementations, the TX device 810 may be Figure 1 STA 104 or Figure 6B In some implementations, the RX device 820 may be an example of any of the STAs 604. Figure 1 AP 102 or Fig. 6A In some other implementations, the RX device 820 may be Figure 1 STA 104 or Figure 6B An example of any one of STA604.

[0092] The TX device 810 determines a future transmitter (TX) configuration that will be used to transmit wireless signals to the RX device 820 after the transmission of the test packet. In some implementations, the TX device 810 may indicate the future TX configuration to the RX device 820 prior to the transmission of the test packet. The TX device 810 may then transmit the test packet to the RX device 820 using any TX configuration. For example, the TX device 810 may use a different number of spatial streams (M) than will be used for subsequent data transmission to the RX device 820. SS ) to transmit the test packet. In some aspects, the test packet may be a probing packet such as, for example, a null data packet (NDP), and the future TX configuration may be indicated in an NDP announcement (NDPA) prior to transmission of the NDP.

[0093] The RX device 820 determines a future receiver (RX) type that will be used to receive wireless signals from the TX device 810 after receipt of the test packet. The RX type implemented by the RX device 820 at any given time may be regulated by a state machine. The RX device 820 receives the test packet from the TX device 810 and generates feedback for the wireless channel 830 based at least in part on the received test packet. In some aspects, the feedback may include CSI associated with the wireless channel 830. In some implementations, the RX device 820 may generate one or more SINR estimates for the wireless channel 830. More specifically, each SINR estimate may correspond to an effective SINR associated with a particular modulation order. As described with respect to Figure 7 As described, the effective SINR is the SINR that the RX device 820 estimates will be used for wireless transmissions for a given modulation order.

[0094] Aspects of the present disclosure recognize that the TX configuration and RX type may affect the SINR calculation performed by the RX device 820. For example, the SINR determined for a given combination of TX configuration and RX type may not accurately describe the SINR for different combinations of TX configuration and RX type. In addition, the TX configuration or RX type used to transmit and receive the test packet may be different from the future TX configuration or future RX type, respectively. In some implementations, the RX device 820 may adjust the effective SNR value based at least in part on the future TX configuration and the future RX type. For example, the RX device 820 may predict or infer the SINR associated with the future TX configuration and the future RX type based on the SINR estimated from the received test packet.

[0095] The RX device 820 reports back feedback to the TX device 810, which includes one or more of the SINR estimates. The RX device 820 may further provide an indication of the modulation order associated with each SINR estimate reported back to the TX device 810. In some implementations, the RX device 820 may report a single SINR estimate back to the TX device 810. In some other implementations, the RX device 820 may report multiple SINR estimates back to the TX device 810. In some aspects, the feedback may include information identifying the modulation order associated with each SINR estimate. In some other aspects, the SINR estimates may be pre-arranged based on the modulation order associated with them. Accordingly, the feedback may not include any additional information identifying the modulation order associated with each SINR estimate.

[0096] The TX device 810 receives feedback from the RX device 820 and selects an MCS to be used for subsequent communications with the RX device 820 based at least in part on the SINR estimate(s) and the modulation order associated with each SINR estimate. For example, if the feedback includes only the best SINR estimate, the TX device 810 may select an MCS that follows the modulation order associated with the reported SINR estimate. Alternatively, if the feedback includes multiple SINR estimates, the TX device 810 may balance the effective SINR at the associated modulation order when selecting the MCS to achieve the highest throughput.

[0097] The TX device 810 then transmits one or more packets (TX packets) to the RX device 820 using the selected MCS. As described above, the TX configuration (N) used to transmit the TX packets SS ) may be different from the TX configuration (M SS However, since the RX device 820 adjusts the SINR estimate based on the future TX configuration, the selected MCS can be optimal for the channel conditions, TX configuration, and RX type associated with the transmission and reception of the TX packet.

[0098] Fig. 9 A flow chart illustrating an example process 900 for wireless communication supporting transmitter-based link adaptation according to some implementations is shown. In some implementations, the process 900 may be performed by a wireless communication device as an AP (such as the wireless communication device described above, respectively). Figure 1 , Fig. 6A , Figure 7 and Figure 8 In some other implementations, process 900 may be performed by a wireless communication device operating as a network node (such as one of the APs 102, 602, 710, or 810 described above) or operating within an AP. Figure 1 , Figure 6B , Figure 7 and Figure 8 The method may be performed by one of the described STAs 104, 604, 720, or 820) operating or by a wireless communication device operating within a network node.

[0099] In some implementations, process 900 begins at block 902 with transmitting a first packet to a receiving device on a wireless channel. At block 904, process 900 proceeds to receiving feedback from the receiving device in response to the first packet, wherein the feedback includes one or more SINR estimates associated with the wireless channel. At block 906, process 900 proceeds to determining a corresponding modulation order associated with each of the one or more SINR estimates. In some implementations, the feedback may include information indicating a modulation order associated with each of the one or more SINR estimates. At block 908, process 900 proceeds to selecting an MCS to be used for subsequent communications with the receiving device based on the one or more SINR estimates and the corresponding modulation order associated with each of the one or more SINR estimates.

[0100] In some implementations, the one or more SINR estimates may include multiple SINR estimates, wherein each SINR estimate in the multiple SINR estimates is associated with a different modulation order. In some implementations, selecting to determine the modulation order in block 906 may include: determining an arrangement of the multiple SINR estimates in the received feedback, wherein the modulation order associated with each SINR estimate is determined based on the arrangement of the multiple SINR estimates. In some implementations, selecting the MCS in block 908 may include: estimating a corresponding throughput of the communication associated with each SINR estimate based on the modulation order associated with each SINR estimate in the multiple SINR estimates, wherein the MCS is selected based on the estimated throughput associated with the multiple SINR estimates.

[0101] In some implementations, the process 900 may proceed to transmitting a second packet to the recipient device according to the selected MCS after selecting the MCS in block 908, wherein the second packet is transmitted on a number (N) of spatial streams. In some aspects, the first packet may also be transmitted on the N spatial streams. In some other aspects, the first packet may be transmitted on a different number (M) of spatial streams than the second packet. In some implementations, the process 900 may begin with transmitting a third packet to the recipient device before transmitting the first packet in block 902, wherein the third packet carries information indicating the N spatial streams. In some implementations, the first packet may be an NDP and the third packet may be an NDPA associated with the NDP.

[0102] Fig. 10A A flow chart illustrating an example process 1000 for wireless communication supporting transmitter-based link adaptation according to some implementations is shown. In some implementations, the process 1000 may be performed by a network node (such as the network nodes described above, respectively). Figure 1 , Figure 6B , Figure 7 and Figure 8 104, 604, 720, or 820 described above) or a wireless communication device operating within a network node. In some other implementations, process 1000 may be performed by a wireless communication device operating as an AP (such as the above-described STAs 104, 604, 720, or 820, respectively). Figure 1 , Fig. 6A , Figure 7 and Figure 8 The method may be performed by a wireless communication device operating with or within one of the described APs 102, 602, 710, or 810.

[0103] In some implementations, process 1000 begins at block 1002 with receiving a first packet from a transmitting device on a wireless channel. At block 1004, process 1000 proceeds to determining a receiver type to be used to receive subsequent communications from the transmitting device. In some implementations, the receiver type may be a minimum mean square error (MMSE) receiver type or a maximum likelihood ratio (ML) receiver type. At block 1006, process 1000 proceeds to generating one or more SINR estimates associated with the wireless channel based on receiving the first packet and the receiver type to be used to receive subsequent communications. At block 1008, process 1000 proceeds to transmitting feedback to the transmitting device, the feedback including at least one of the one or more SINR estimates. In some implementations, the feedback may include information indicating a corresponding modulation order associated with each of the one or more SINR estimates.

[0104] In some implementations, the one or more SINR estimates may include multiple SINR estimates, wherein each SINR estimate in the multiple SINR estimates is associated with a different modulation order. In some implementations, the process 1000 may proceed to estimating the corresponding throughput of the communication associated with each SINR estimate based on the modulation order associated with each SINR estimate in the multiple SINR estimates before transmitting the feedback in block 1008; and selecting one SINR estimate in the multiple SINR estimates to be included in the feedback based on the estimated throughput associated with each SINR estimate in the multiple SINR estimates. In some other implementations, the feedback may include the multiple SINR estimates. In some implementations, the process 1000 may proceed to arranging the multiple SINR estimates in the feedback according to the modulation order associated with each SINR estimate before transmitting the feedback in block 1008.

[0105] In some implementations, process 1000 may proceed to receiving a second packet from the transmitting device before receiving the first packet after transmitting the feedback in block 1008, the second packet carrying information indicating a number of spatial streams associated with subsequent communications; and adjusting each of the one or more SINR estimates based on the number of spatial streams associated with the subsequent communications. In some implementations, the first packet may be an NDP and the second packet may be an NDPA associated with the NDP.

[0106] Fig. 10B A flow chart illustrating an example process 1010 for wireless communication supporting transmitter-based link adaptation according to some implementations is shown. In some implementations, the process 1010 may be performed by a network node (such as the above-mentioned reference 1010, respectively). Figure 1 , Figure 6B , Figure 7 and Figure 8 104, 604, 720, or 820 described above) or a wireless communication device operating within a network node. In some other implementations, process 1010 may be performed by a wireless communication device operating as an AP (such as the above-described STAs 104, 604, 720, or 820, respectively). Figure 1 , Fig. 6A , Figure 7 and Figure 8 The method may be performed by a wireless communication device operating with or within one of the described APs 102, 602, 710, or 810.

[0107] See for example Fig. 10A, process 1010 may be a more detailed implementation of the operations for generating the one or more SINR estimates described in block 1006 of process 1000. For example, process 1010 may begin at block 1012 after determining the receiver type in block 1004 of process 1000 and before transmitting the feedback in block 1008. In some implementations, process 1010 begins at block 1012 to determine a corresponding SINR for each of a plurality of tones for the wireless channel. At block 1014, process 1000 proceeds to determine a corresponding channel capacity for each of the plurality of tones based on the determined SINR for each tone. At block 1016, process 1010 proceeds to calculate a linear average of the determined channel capacities. At block 1018, process 1010 proceeds to map the linear averages to one or more constrained capacity curves associated with one or more modulation orders, respectively, wherein each of the one or more SINR estimates is determined based on the mapping of the linear average to the corresponding constrained capacity curve.

[0108] Fig.11 1 shows a block diagram of an example wireless communication device 1100 according to some implementations. In some implementations, the wireless communication device 1100 is configured to perform the above reference Fig. 9 The wireless communication device 1100 may be the one described above with reference to Figure 5 Example implementations of the described wireless communication device 500. For example, the wireless communication device 1100 may be a chip, SoC, chipset, package, or device that includes at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0109] The wireless communication device 1100 includes a receiving component 1110, a communication manager 1120, and a transmission component 1130. The communication manager 1120 further includes a modulation order determination component 1122 and an MCS selection component 1124. Portions of one or more of the components 1122 and 1124 may be implemented at least in part in hardware or firmware. In some implementations, at least some of the components 1122 or 1124 are implemented at least in part as software stored in a memory, such as the memory 508. For example, portions of one or more of the components 1122 and 1124 may be implemented as non-transient instructions (or "code") that can be executed by a processor, such as the processor 506, to perform the functions or operations of the corresponding components.

[0110] The receiving component 1110 is configured to receive RX signals from one or more other wireless communication devices on a wireless channel. In some implementations, these RX signals may include feedback from a receiving device in response to a first packet, wherein the feedback includes one or more SINR estimates associated with the wireless channel. The transmission component 1130 is configured to transmit TX signals to one or more other wireless communication devices. In some implementations, these TX signals may include a first packet transmitted to the receiving device. The communication manager 1120 is configured to control or manage communications with the one or more other wireless communication devices. In some implementations, the modulation order determination component 1122 may determine the corresponding modulation order associated with each of the one or more SINR estimates; and the MSC selection component 1124 may select the MCS to be used for subsequent communications with the receiving device based on the one or more SINR estimates and the corresponding modulation order associated with each of the one or more SINR estimates.

[0111] Fig.12 1 shows a block diagram of an example wireless communication device 1200 according to some implementations. In some implementations, the wireless communication device 1200 is configured to perform the above reference Fig. 10A The wireless communication device 1100 may be the process 1000 described above. Figure 5 Example implementations of the described wireless communication device 500. For example, the wireless communication device 1200 may be a chip, SoC, chipset, package, or device that includes at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0112] The wireless communication device 1200 includes a receiving component 1210, a communication manager 1220, and a transmission component 1230. The communication manager 1220 further includes a receive (RX) type determination component 1222 and a SINR estimation component 1224. Portions of one or more of the components 1222 and 1224 may be implemented at least in part in hardware or firmware. In some implementations, at least some of the components 1222 or 1224 are implemented at least in part as software stored in a memory (such as memory 508). For example, portions of one or more of the components 1222 and 1224 may be implemented as non-transient instructions (or "code") that can be executed by a processor (such as processor 506) to perform the functions or operations of the corresponding components.

[0113] The receiving component 1210 is configured to receive RX signals from one or more other wireless communication devices on a wireless channel. In some implementations, these RX signals may include a first packet received from the transmitting device. The transmission component 1230 is configured to transmit TX signals to one or more other wireless communication devices. In some implementations, these TX signals may include feedback transmitted to the transmitting device in response to the first packet. The communication manager 1220 is configured to control or manage communications with the one or more other wireless communication devices. In some implementations, the RX type determination component 1222 may determine the type of receiver to be used to receive subsequent communications from the transmitting device; and the SINR estimation component 1224 may generate one or more SINR estimates associated with the wireless channel based on the first packet received and the type of receiver to be used to receive subsequent communications. In some implementations, at least one of the one or more SINR estimates may be included in the feedback transmitted to the transmitting device.

[0114] As used herein, a phrase referring to "at least one of" or "one or more of" a list of items refers to any combination of those items, including single members. For example, "at least one of a, b, or c" is intended to cover the following possibilities: only a, only b, only c, a combination of a and b, a combination of a and c, a combination of b and c, and a combination of a, b, and c.

[0115] The various illustrative components, logic, logic blocks, modules, circuits, operations, and algorithmic processes described in conjunction with the implementations disclosed herein may be implemented as electronic hardware, firmware, software, or a combination of hardware, firmware, or software, including the structures disclosed in this specification and their structural equivalents. This interchangeability of hardware, firmware, and software has been generally described in terms of their functionality and is illustrated in the various illustrative components, blocks, modules, circuits, and processes described above. Whether such functionality is implemented in hardware, firmware, or software depends on the specific application and the design constraints imposed on the overall system.

[0116] Various modifications to the implementations described in this disclosure may be apparent to those of ordinary skill in the art, and the universal principles defined herein may be applied to other implementations without departing from the spirit or scope of the disclosure. Thus, the claims are not intended to be limited to the implementations shown herein, but should be granted the widest scope consistent with the disclosure, the principles and novel features disclosed herein.

[0117] In addition, various features described in this specification in the context of separate implementations may also be implemented in combination in a single implementation. Conversely, various features described in the context of a single implementation may also be implemented in multiple implementations separately or in any suitable subcombination. Thus, while features may be described above as functioning in a particular combination and even initially claimed as such, one or more features from a claimed combination may in some cases be removed from the combination, and a claimed combination may be directed to a subcombination, or a variation of a subcombination.

[0118] Similarly, although operations are depicted in a particular order in the accompanying drawings, this should not be understood as requiring such operations to be performed in the particular order shown or in a sequential order, or to perform all the illustrated operations to achieve the desired result. In addition, the accompanying drawings may schematically depict one or more example processes in the form of a flow chart or a flow diagram. However, other operations that are not depicted may be incorporated into the example processes schematically illustrated. For example, one or more additional operations may be performed before, after, simultaneously or between any illustrated operations. In some environments, multitasking and parallel processing may be advantageous. In addition, the separation of various system components in the implementation described above should not be understood as requiring such separation in all implementations, and it should be understood that the described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

Claims

1. A method for performing wireless communication by a wireless communication device associated with a wireless local area network (WLAN), comprising: transmitting a first packet to a recipient device associated with the WLAN over a wireless channel associated with the WLAN; receiving feedback from the recipient device in response to the first packet, the feedback comprising one or more signal-to-interference-plus-noise ratio (SINR) estimates associated with the wireless channel, wherein the feedback comprises information indicating a respective modulation order on which each of the one or more SINR estimates is based at least in part; as well as A modulation and coding scheme (MCS) to be used for subsequent communications with the recipient device is selected based on the one or more SINR estimates and a corresponding modulation order associated with each of the one or more SINR estimates.

2. The method of claim 1, further comprising: A second packet is transmitted to the recipient device according to the selected MCS, the second packet being transmitted on the N spatial streams.

3. The method of claim 2, wherein the first packet is transmitted on the N spatial streams.

4. The method of claim 2, wherein the first packet is transmitted on a different number M of spatial streams than the second packet.

5. The method of claim 4, further comprising: A third packet is transmitted to the receiving device before the first packet is transmitted, the third packet carrying information indicating the N spatial streams.

6. The method of claim 5, wherein the first packet is a Null Data Packet (NDP), and the third packet is an NDP Announcement (NDPA) associated with the NDP.

7. The method of claim 1, wherein the one or more SINR estimates include a plurality of SINR estimates, each SINR estimate in the plurality of SINR estimates being associated with a different modulation order.

8. The method of claim 7, further comprising: An arrangement of the plurality of SINR estimates in the received feedback is determined, a respective modulation order associated with each SINR estimate being determined based on the arrangement of the plurality of SINR estimates.

9. The method of claim 7, wherein selecting the MCS comprises: A respective throughput of the communication associated with each SINR estimate is estimated based on a respective modulation order based at least in part on each SINR estimate of the plurality of SINR estimates, the MCS being selected based on the estimated throughput associated with the plurality of SINR estimates.

10. A wireless communication device associated with a wireless local area network (WLAN), comprising: at least one modem; at least one processor communicatively coupled to the at least one modem; as well as at least one memory communicatively coupled to the at least one processor and storing processor-readable code that, when executed by the at least one processor in conjunction with the at least one modem, is configured to: transmitting a first packet to a recipient device associated with the WLAN over a wireless channel associated with the WLAN; receiving feedback from the recipient device in response to the first packet, the feedback comprising one or more signal-to-interference-plus-noise ratio (SINR) estimates associated with the wireless channel, wherein the feedback comprises information indicating a respective modulation order on which each of the one or more SINR estimates is based at least in part; as well as A modulation and coding scheme (MCS) to be used for subsequent communications with the recipient device is selected based on the one or more SINR estimates and the corresponding modulation order associated with each of the one or more SINR estimates.

11. The wireless communication device of claim 10, wherein execution of the processor readable code is further configured to: A second packet is transmitted to the recipient device according to the selected MCS, the second packet being transmitted on the N spatial streams.

12. The wireless communication device of claim 11, wherein the first packet is transmitted on the N spatial streams.

13. The wireless communication device of claim 11, wherein the first packet is transmitted on a different number M of spatial streams than the second packet.

14. The wireless communication device of claim 13, wherein execution of the processor readable code is further configured to: A third packet is transmitted to the receiving device before the first packet is transmitted, the third packet carrying information indicating the N spatial streams.

15. The wireless communication device of claim 14, wherein the first packet is a Null Data Packet (NDP), and the third packet is an NDP Announcement (NDPA) associated with the NDP.

16. The wireless communication device of claim 10, wherein the one or more SINR estimates include a plurality of SINR estimates, each SINR estimate in the plurality of SINR estimates being associated with a different modulation order.

17. The wireless communication device of claim 16, wherein execution of the processor readable code is further configured to: An arrangement of the plurality of SINR estimates in the received feedback is determined, the respective modulation order on which each SINR estimate is based at least in part being determined based on the arrangement of the plurality of SINR estimates.

18. A method for performing wireless communications by a wireless communication device associated with a wireless local area network (WLAN), comprising: receiving a first packet from a transmitting device associated with the WLAN over a wireless channel associated with the WLAN; determining a type of receiver to be used to receive subsequent communications from the transmitting device; generating one or more signal-to-interference-plus-noise ratio (SINR) estimates associated with the wireless channel based on receiving the first packet and the type of receiver to be used to receive the subsequent communication; as well as Feedback including at least one of the one or more SINR estimates is transmitted to the transmitting device, wherein the feedback includes information indicating a respective modulation order on which each of the one or more SINR estimates is based at least in part.

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