Antenna switching in frequency bands with power spectral density (PSD) limitation

Abstract

The present disclosure provides methods, devices, and systems for improving wireless communications in power spectral density (PSD) limited frequency bands. A wireless communication device having a number (NTX) of transmit antennas parses physical layer (PHY) protocol data units (PPDUs) into a number (NSS) of spatial streams and modulates the NSS of spatial streams onto a number (M) of subcarriers. In some implementations, a wireless communication device may transmit a PPDU using a number (N) of transmit antennas, where NSS < = Nlt; and NTX. In some other implementations, a wireless communication device may subdivide M subcarriers into subcarrier groups, and may transmit each subcarrier group using a respective subset of NTX transmit antennas, where the number of transmit antennas for transmitting each subcarrier group is greater than or equal to the number of spatial streams modulated onto the subcarriers in the group, and where the number of transmit antennas for transmitting each subcarrier group is greater than or equal to the number of spatial streams modulated onto the subcarriers in the group. But less than NTX.

Description

[0001] Cross-references

[0002] This patent application claims priority to U.S. patent application No. 17 / 820,006, filed by Wu et al. on August 16, 2022, and entitled “Antenna Switching In Frequency Bands With Power Spectral Density (PSD) Limits,” which is assigned to the assignee of this application and is expressly incorporated herein by reference. Technical Field

[0003]

[0002] The present disclosure relates generally to wireless communications and, more particularly, to antenna switching in frequency bands with power spectral density (PSD) limitations. Background Art

[0004] A wireless local area network (WLAN) may be formed by one or more wireless access points (APs) that provide a shared wireless communication medium for use by a number of 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 series of standards is a basic service set (BSS), which is managed by an AP. Each BSS is identified by a basic service set identifier (BSSID) advertised by the AP. The AP periodically broadcasts beacon frames so that any STA within the wireless range of the AP can establish or maintain a communication link with the WLAN.

[0005] In some cases, APs and STAs may be subject to power spectral density (PSD) limitations. For example, some APs and STAs operating in the 6 Gigahertz (GHz) band may be required to comply with the low power indoor (LPI) power class, which limits the transmit power of the AP and STA (in the 6 GHz band) to 5 decibel milliwatts per megahertz (dBm / MHz) and -1 dBm / MHz, respectively. When wireless signals are sent via multiple transmit antennas (such as antenna arrays), the energy radiated in the direction of the strongest beam must not exceed the PSD limit. Such limitations on directional gain apply to beamformed transmissions as well as open-loop transmissions using multiple transmit antennas (which may result in unintentional beamforming in one or more directions). As a result, PSD limitations may undesirably reduce the range of wireless communications, and may reduce the packet detection and channel estimation capabilities of the AP and STA. Summary of the invention

[0006] 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.

[0007] One innovative aspect of the subject matter described in the present disclosure can be implemented as a method of wireless communication. The method can include a number (N) of TX ) transmit antennas, and may include parsing a physical layer (PHY) protocol data unit (PPDU) into a number (N SS ) spatial streams, where N SS ≥1; N SS The spatial streams are modulated onto a number (M) of subcarriers across a bandwidth associated with a wireless channel; the M subcarriers are mapped to a number (N) of transmit antennas based on a power spectral density (PSD) constraint associated with the wireless channel, where N SS ≤N <N TX ; and sending the PPDU to the receiving device via N transmit antennas based on the mapping of the M subcarriers. In some implementations, N may be equal to N SS .

[0008] In some aspects, the method may also include receiving antenna selection information indicating the N transmit antennas from the receiving device. In some other aspects, the mapping of the M subcarriers to the N transmit antennas may be further based on indicating the N transmit antennas to be used for transmission. SS In some other aspects, the mapping of the M subcarriers to the N transmit antennas is further based on a lookup table storing historical data associated with previous transmissions by the wireless communication device.

[0009] Further, the method may also include receiving channel state information (CSI) from the receiving device, wherein the M subcarriers are mapped to the N transmit antennas based on the received CSI. In some implementations, the N transmit antennas may be associated with the N highest signal-to-noise ratios (SNRs) or the N highest signal-to-interference-plus-noise ratios (SINRs) indicated by the received CSI. In some implementations, the N transmit antennas may be associated with the highest channel gain indicated by the received CSI.

[0010] In some implementations, the N transmit antennas may include a first transmit antenna associated with a highest channel gain indicated by the received CSI, and a TX A second transmit antenna having the lowest correlation with the first transmit antenna among the N transmit antennas. In some implementations, the N transmit antennas may also include TX A third transmit antenna among the plurality of transmit antennas having the lowest correlation with the first transmit antenna and the second transmit antenna.

[0011] In some implementations, the N transmit antennas may include a first transmit antenna associated with a highest channel gain indicated by the received CSI, and a second transmit antenna associated with a highest channel gain indicated by the received CSI in a direction orthogonal to the first transmit antenna. In some implementations, the N transmit antennas may also include a third transmit antenna having a highest channel gain indicated by the received CSI in a direction orthogonal to the first transmit antenna and the second transmit antenna.

[0012] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a wireless communication device. In some implementations, the wireless communication device may include a number (N TX ) transmit antennas; at least one memory; and at least one processor, which is communicatively coupled to the at least one memory and configured to cause the wireless communication device to perform operations including the following: parsing the PPDU into a number (N SS ) spatial streams, where N SS ≥1; N SS The spatial streams are modulated onto a number (M) of subcarriers across a bandwidth associated with a wireless channel; the M subcarriers are mapped to a number (N) of transmit antennas based on a PSD limit associated with the wireless channel, where N SS ≤N <N TX ; and sending the PPDU to a receiving device via N transmit antennas based on the mapping of the M subcarriers.

[0013] Another innovative aspect of the subject matter described in the present disclosure can be implemented as a method of wireless communication. The method can be performed by a wireless communication device and can include parsing a PPDU into a number (N SS ) spatial streams, where N SS ≥1; N SS spatial streams modulated onto a number (M) of subcarriers across a bandwidth associated with a wireless channel; based on the number of spatial streams modulated onto a first subset of the M subcarriers (N SS1 ) to map the first subset of M subcarriers to a number (K) of transmit antennas, where N SS1 ≤K <N TX ; Based on the number of spatial streams modulated onto the second subset of M subcarriers (N SS2 ) to map the second subset of M subcarriers to a number (L) of transmit antennas, where N SS2 ≤L <N TX ; Based on the mapping of the first subset of the M subcarriers to send the first part of the PPDU to the receiving device via the K transmit antennas; and based on the mapping of the second subset of the M subcarriers to send the second part of the PPDU to the receiving device via the L transmit antennas.

[0014] In some implementations, K may be equal to N SS1 And L can be equal to N SS2 In some implementations, the K transmit antennas may be different from the L transmit antennas. In some implementations, the mapping of the first subset and the second subset of the M subcarriers to the K transmit antennas and the L transmit antennas, respectively, may be further based on a PSD limit associated with the wireless channel.

[0015] In some implementations, subcarriers belonging to a first subset of M subcarriers may be unique to the first subset, and subcarriers belonging to a second subset of the M subcarriers may be unique to the second subset. In some implementations, the first subset of M subcarriers may represent one or more first resource units (RUs), and the second subset of M subcarriers may represent one or more second RUs. In some implementations, the first subset of M subcarriers may include a different number of subcarriers than the second subset of M subcarriers.

[0016] In some aspects, the method may further include receiving antenna selection information indicating the K transmit antennas or the L transmit antennas from the receiving device. In some other aspects, the mapping of the first subset or the second subset of the M subcarriers to the K transmit antennas or the L transmit antennas, respectively, may be further based on indicating that the K transmit antennas are to be used to transmit the N SS1 spatial streams and L transmit antennas are used to send N SS2 In some other aspects, mapping of the first subset or the second subset of M subcarriers to the K transmit antennas or the L transmit antennas, respectively, can be further based on a lookup table storing historical data associated with previous transmissions by the wireless communication device.

[0017] Further, in some aspects, the method may also include receiving CSI from a receiving device, wherein the mapping of the first subset or the second subset of the M subcarriers to the K transmit antennas or the L transmit antennas, respectively, is further based on the received CSI. In some implementations, the mapping of the first subset of the M subcarriers to the K transmit antennas may be based on a lookup table, and the mapping of the second subset of the M subcarriers to the L transmit antennas may be based on the received CSI.

[0018] In some implementations, the method may further include modulating the spatial streams onto the third subset of the M subcarriers based on the number of spatial streams (N SS3 ) to map the third subset of M subcarriers to a number (J) of transmit antennas, where N SS3 ≤J <N TX; and sending a third part of the PPDU to the receiving device via the J transmit antennas based on the mapping of the third subset of the M subcarriers.

[0019] Another innovative aspect of the subject matter described in the present disclosure can be implemented in a wireless communication device. In some implementations, the wireless communication device may include a number (N TX ) transmit antennas; at least one memory; and at least one processor, which is communicatively coupled to the at least one memory and configured to cause the wireless communication device to perform operations including the following: parsing the PPDU into a number (N SS ) spatial streams, where N SS ≥1; N SS spatial streams modulated onto a number (M) of subcarriers across a bandwidth associated with a wireless channel; based on the number of spatial streams modulated onto a first subset of the M subcarriers (N SS1 ) to map the first subset of M subcarriers to a number (K) of transmit antennas, where N SS1 ≤K <N TX ; Based on the number of spatial streams modulated onto the second subset of M subcarriers (N SS2 ) to map the second subset of M subcarriers to a number (L) of transmit antennas, where N SS2 ≤L <N TX ; Based on the mapping of the first subset of the M subcarriers to send the first part of the PPDU to the receiving device via the K transmit antennas; and based on the mapping of the second subset of the M subcarriers to send the second part of the PPDU to the receiving device via the L transmit antennas. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the specification, drawings, and claims. It should be noted that the relative sizes of the following drawings may not be drawn to scale.

[0021] Figure 1 A schematic diagram of an example wireless communication network is shown.

[0022] Figure 2A An example protocol data unit (PDU) that can be used for communications between an access point (AP) and one or more wireless stations (STAs) is shown.

[0023] Figure 2B Show Figure 2A Example fields in a PDU.

[0024] Figure 3An example physical layer convergence protocol (PLCP) protocol data unit (PPDU) that can be used for communications between an AP and one or more STAs is shown.

[0025] Figure 4 A block diagram of an example wireless communication device is shown.

[0026] Figure 5A A block diagram of an example AP is shown.

[0027] Figure 5B A block diagram of an example STA is shown.

[0028] Figure 6 A block diagram of an example transmitter for a wireless communication device is shown in accordance with some implementations.

[0029] Figure 7 A frequency diagram is shown depicting an example mapping of PPDUs to a subset of transmit (TX) antennas according to some implementations.

[0030] Figure 8 Another frequency diagram is shown depicting an example mapping of PPDUs to subsets of TX antennas according to some implementations.

[0031] Fig. 9 Another block diagram of an example transmitter for a wireless communication device is shown in accordance with some implementations.

[0032] Fig.10 A block diagram of an example antenna switching system is shown in accordance with some implementations.

[0033] Fig.11 A flow chart illustrating an example process for supporting wireless communications with antenna switching in a frequency band having power spectral density (PSD) limitations is shown.

[0034] Fig.12 A flow chart illustrating an example process for supporting wireless communications with antenna switching in a frequency band with PSD limitations is shown.

[0035] Fig.13 A block diagram of an example wireless communication device is shown in accordance with some implementations.

[0036] Fig.14 A block diagram of an example wireless communication device is shown in accordance with some implementations.

[0037] Like reference numbers and designations in the various drawings indicate like elements. DETAILED DESCRIPTION

[0038] For the purpose of describing the innovative aspects of the present disclosure, the following description is directed to certain implementations. However, one of ordinary skill in the art will readily recognize that the teachings herein can be applied in a variety of different ways. The described implementations can be implemented in any device, system, or network capable of sending and receiving radio frequency (RF) signals in accordance with one or more of the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standards, IEEE 802.15 standards, as defined by the Bluetooth Special Interest Group (SIG), or any other standard. Standards, or Long Term Evolution (LTE), 3G, 4G or 5G (New Radio (NR)) standards issued by the Third Generation Partnership Project (3GPP), and others. The described implementations can be implemented in any device, system or network capable of sending 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 can also be implemented using other wireless communication protocols or RF signals suitable for use in one or more of the following: Wireless Personal Area Network (WPAN), Wireless Local Area Network (WLAN), Wireless Wide Area Network (WWAN) or Internet of Things (IOT) network.

[0039] As described above, wireless communications in some frequency bands (such as the 6 GHz band) are subject to power spectral density (PSD) limits. When wireless signals are sent via multiple antennas (such as an antenna array), the energy radiated in any given direction must not exceed the PSD limit of the wireless channel. The directional gain of a wireless transmission is equal to the gain of each antenna plus any array gain that may occur when signals sent on different antennas are positively correlated in a particular direction (such as in beamformed transmissions or open-loop transmissions that result in unintentional beamforming). A wireless signal is "correlated" if the same digital data is sent via two or more antennas in a given symbol period (even with different encoding or phase shifts). Therefore, correlated signals may exist at any frequency or time delay.

[0040] With any number (N TX ) transmit antennas (or radio chains) typically use all N TX transmit antennas are used for wireless transmission, for example, to maximize spatial diversity. For open-loop transmission, N TX antennas can be configured to transmit less than or equal to the number of available transmit antennas N TX Any number (N SS ) spatial streams. In other words, NSS The spatial streams must use at least N SS When the number of spatial streams N SS Less than the number of available transmit antennas N TX When transmitting multiple copies of the same data via multiple transmit antennas, wireless communication devices can use space-time block coding (STBC) or precoding matrices. As a result, existing wireless communication devices generally incur a power penalty due to the array gain (A) associated with multi-antenna transmission, where Aspects of the present disclosure recognize that the power penalty associated with open-loop transmission may be reduced by avoiding transmission of related signals.

[0041] Various aspects are generally directed to improving wireless communications in PSD limited frequency bands, and more particularly, to reducing the power penalty associated with open loop transmission in PSD limited frequency bands. TX ) transmit antennas can parse a physical layer (PHY) protocol data unit (PPDU) into a number (N SS ) spatial streams, and N SS The spatial streams are modulated onto a number (M) of subcarriers (where N SS ≥1). In some aspects, a wireless communication device may map M subcarriers to a number (N) of transmit antennas, where N SS ≤N <N TX , and the PPDU can be sent to the receiving device based on the mapping of the M subcarriers to the N transmit antennas. More specifically, the wireless communication device can send N SS In some other aspects, the wireless communication device may subdivide the M subcarriers into two or more groups, and may map each subcarrier group to N TX The number of transmit antennas mapped to each subcarrier group is greater than or equal to the number of spatial streams modulated onto the subcarriers in the group, but less than N. TX In such an aspect, the wireless communication device may transmit the PPDU based on the mapping of subcarrier groups to transmit antenna subsets. More specifically, the wireless communication device may transmit the spatial streams associated with each subcarrier group using only the transmit antennas mapped to the subcarrier group.

[0042] Specific implementations of the subject matter described in the present disclosure may be performed to achieve one or more of the following potential advantages. Implementations herein may reduce the power penalty associated with open-loop transmission in a PSD-limited band by reducing or eliminating the transmission of correlated signals. Various aspects of the present disclosure may reduce the number of correlated signals associated with open-loop transmission (compared to existing open-loop transmission techniques) by using some but not all of the available transmit antennas to transmit any number of spatial streams. For example, by mapping a PPDU to a number of transmit antennas (N=N) that is equal to the number of spatial streams associated with the PPDU. SS ), the wireless communication device can send N unrelated signals via N transmitting antennas respectively (where N <N TX Additionally or alternatively, by mapping different groups of subcarriers (modulated with different portions of the PPDU) to different subsets of transmit antennas, aspects of the present disclosure may decorrelate the signals sent by each antenna (and, therefore, compare the signals transmitted by each antenna to the N antennas where the PPDU as a whole is mapped to the N antennas). SS ≤N <N TX Compared with the implementation of multiple antennas, a larger number of available transmit antennas can be utilized for open-loop transmission. For example, by subdividing M subcarriers into N TX subcarrier groups, the wireless communication device can respectively TX The antenna transmits N TX Such techniques for reducing the power penalty associated with open-loop transmission can be used to increase the range of wireless communications, as well as improve packet detection and channel estimation capabilities of wireless communication devices in PSD-limited frequency bands.

[0043] Figure 1 A 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 802.11-2020 specification or amendments thereof, which include, but are 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.

[0044] Each of the STAs 104 may also be referred to as a mobile station (MS), a mobile device, a mobile phone, a wireless phone, an access terminal (AT), a user equipment (UE), a subscriber station (SS), or a subscriber unit, among other possibilities. The STAs 104 may represent a variety of devices, such as mobile phones, personal digital assistants (PDAs), other handheld devices, netbooks, notebook computers, tablet computers, laptop computers, display devices (e.g., TVs, computer monitors, navigation systems, and others), music or other audio or stereo equipment, remote control devices (“remote controls”), printers, kitchen or other home appliances, key cards (e.g., for passive keyless entry and start (PKES) systems), and other possibilities.

[0045] 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 1 Also shown is an example coverage area 108 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 to other devices by a basic service set identifier (BSSID), which may be a medium 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 respective communication link 106 (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 respective 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 the respective STAs 104 in the WLAN via the respective communication links 106.

[0046] To establish a communication link 106 with the AP 102, each of the STAs 104 is configured to perform a passive or active scanning operation (“scan”) on frequency channels in one or more frequency bands (e.g., 2.4 GHz, 5 GHz, 6 GHz, or 60 GHz bands). To perform a passive scan, the STAs 104 listen to beacons transmitted by the respective APs 102 at periodic time intervals (measured in time units (TUs), where one TU may be equal to 1024 microseconds (μs)) called target beacon transmission times (TBTTs). To perform an active scan, the STAs 104 generate probe requests and sequentially transmit probe requests on each channel to be scanned, and listen for probe responses from the APs 102. Each STA 104 may be configured to identify or select an AP 102 with which to associate based on the scan information obtained through the passive or active scan, and to perform authentication and association operations to establish a communication link 106 with the selected AP 102. The AP 102 assigns an association identifier (AID) to the STA 104 upon culmination of the association operation, and the AP 102 tracks the STA 104 using the AID.

[0047] As a result of the increasing popularity of wireless networks, a 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. Extended network stations associated with the WLAN 100 may be connected to a wired or wireless distribution system that may allow multiple APs 102 to be connected in such an ESS. As such, a 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. In addition, after association with an AP 102, the 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 a more desirable network characteristic, such as a larger received signal strength indicator (RSSI) or a reduced traffic load.

[0048] In some cases, STA 104 can form a network without AP 102 or other devices other than STA 104 itself. An example of such a network is an ad hoc network (or wireless ad hoc network). Ad hoc networks can be alternatively referred to as mesh networks or peer-to-peer (P2P) networks. In some cases, ad hoc networks can be implemented in larger wireless networks (such as WLAN 100). In such an implementation, although STA 104 may be able to communicate with each other through AP 102 using communication link 106, STA 104 can also communicate directly with each other via direct wireless link 110. In addition, two STAs 104 can communicate via direct communication link 110, regardless of whether both STAs 104 are associated with the same AP 102 and served by the same AP 102. In such an ad hoc system, one or more STAs in STA 104 can assume the role played by AP 102 in the BSS. Such STA 104 can be called a group owner (GO), and can coordinate transmissions 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 Tunnel Direct Link Setup (TDLS) link, and other P2P group connections.

[0049] The AP 102 and the STA 104 may operate and communicate (via respective communication links 106) 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 amendments, which include, but are 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 (physical) layer and the medium access control (MAC) layer. The AP 102 and the STA 104 send and receive wireless communications in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs) to and from each other (hereinafter also referred to as "Wi-Fi communications"). The AP 102 and STA 104 in the WLAN 100 may send 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 700 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, which may support both licensed and unlicensed communications. The AP 102 and STA 104 may also be configured to communicate in other frequency bands, such as shared licensed bands, where multiple operators may have licenses to operate in the same or overlapping frequency bands or multiple frequency bands.

[0050] Each frequency band in the frequency band may include multiple sub-bands or multiple frequency channels. For example, a PPDU that complies with IEEE 802.11n, 802.11ac, 802.11ax, and 802.11be standard revisions may be sent on a 2.4, 5 GHz, or 6 GHz frequency band, with each frequency band in the frequency band being divided into multiple 20 MHz channels. As such, these PPDUs are sent on a physical channel with a minimum bandwidth of 20 MHz, but larger channels may be formed by channel bonding. For example, a PPDU may be sent on a physical channel with a bandwidth of 40 MHz, 80 MHz, 160 MHz, or 320 MHz by bonding multiple 20 MHz channels together.

[0051] Each PPDU is a composite structure including a PHY preamble and a payload in the form of a PHY 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 a PPDU is sent on a bonded channel, the preamble field can be copied and sent in each component channel in a plurality of component channels. The PHY preamble can include both a traditional part (or "traditional preamble") and a non-traditional part (or "non-traditional preamble"). Traditional preambles can be used for packet detection, automatic gain control, channel estimation, and other purposes. Traditional preambles can also be used to maintain compatibility with traditional devices. The format of the non-traditional part of the preamble, the encoding of the non-traditional part of the preamble, and the information provided in the non-traditional part of the preamble are based on the specific IEEE 802.11 protocol to be used to send the payload.

[0052] Figure 2A An example protocol data unit (PDU) 200 that can be used for wireless communication between an AP 102 and one or more STAs 104 is shown. For example, the PDU 200 can be configured as a PPDU. As shown, the PDU 200 includes a PHY preamble 202 and a PHY payload 204. For example, the preamble 202 can include a legacy portion, 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 two BPSK symbols. The legacy portion of the preamble 202 can be configured according to the IEEE 802.11a wireless communication protocol standard. The preamble 202 can also include a non-legacy portion, which includes, for example, one or more non-legacy fields 212 that conform to an IEEE wireless communication protocol (such as IEEE 802.11ac, 802.11ax, 802.11be, or one or more later wireless communication protocols).

[0053] 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 uses the determined duration to avoid sending over 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 can include PSDU, which includes a data field (DATA) 214, which can then carry higher layer data in the form of a medium access control (MAC) protocol data unit (MPDU) or an aggregated MPDU (A-MPDU).

[0054] Figure 2B Shown in Figure 2A 2. Example L-SIG 210 in PDU 200 of FIG. L-SIG 210 includes a data rate field 222, reserved bits 224, a length field 226, parity bits 228, and a tail field 230. Data rate field 222 indicates the data rate (note that the data rate indicated in data rate field 212 may not be the actual data rate of the data carried in payload 204). Length field 226 indicates the length of the packet in units of, for example, symbols or bytes. Parity bits 228 can be used to detect bit errors. Tail field 230 includes tail bits that can be used by a receiving device to terminate the operation of a decoder (e.g., a Viterbi decoder). The receiving device can use the data rate and length indicated in data rate field 222 and length field 226 to determine the duration of the packet in units of, for example, microseconds (μs) or other time units.

[0055] Figure 3An example PPDU 300 is shown that can be used for communication between an AP 102 and one or more STAs 104. As described above, each PPDU 300 includes a PHY preamble 302 and a PSDU 304. Each PSDU 304 may represent (or "carry") one or more MAC protocol data units (MPDUs) 316. For example, each PSDU 304 may carry an aggregated MPDU (A-MPDU) 306 that includes an aggregation of multiple A-MPDU subframes 308. Each A-MPDU subframe 306 may include an MPDU frame 310 that includes a MAC delimiter 312 and a MAC header 314 before the accompanying MPDU 316, and the MPDU 316 includes a data portion ("payload" or "frame body") of the MPDU frame 310. Each MPDU frame 310 may also include a frame check sequence (FCS) field 318 for error detection (e.g., the FCS field may include a cyclic redundancy check (CRC)) and padding bits 320. The MPDU 316 may carry one or more MAC service data units (MSDUs) 326. For example, the MPDU 316 may carry an aggregated MSDU (A-MSDU) 322 that includes multiple A-MSDU subframes 324. Each A-MSDU subframe 324 includes a corresponding MSDU 330, preceded by a subframe header 328, and followed by padding bits 332 in some cases.

[0056] Referring back to the MPDU frame 310, the MAC delimiter 312 may serve as a marker for the start of the associated MPDU 316, as well as indicating the length of the associated MPDU 316. The MAC header 314 may include a plurality of fields containing information defining or indicating characteristics or attributes of the data encapsulated within the frame body 316. The MAC header 314 includes a duration field indicating a duration extending from the end of the PPDU at least until the end of an acknowledgement (ACK) or block ACK (BA) of the PPDU to be sent by the receiving wireless communication device. The use of the duration field is used to reserve the wireless medium for the indicated duration, and to enable the receiving device to establish its network allocation vector (NAV). The MAC header 314 also includes one or more fields indicating an address for the data encapsulated within the frame body 316. For example, the MAC header 314 may include a combination of a source address, a transmitter address, a receiver address, or a destination address. The MAC header 314 may also include a frame control field containing control information. The frame control field may specify a frame type, such as a data frame, a control frame, or a management frame.

[0057] Figure 44 is a block diagram of an example wireless communication device 400. In some implementations, the wireless communication device 400 may be a device for communicating with a STA (such as a reference Figure 1 104) described herein. In some implementations, the wireless communication device 400 may be an example of a device used in an AP (such as a STA 104 described in the reference Figure 1 The wireless communication device 400 is an example of a device used in the AP 102 described above. The wireless communication device 400 is capable of sending (or outputting for transmission) and receiving wireless communications (e.g., in the form of wireless packets). For example, the wireless communication device can be configured to send and receive packets in the form of physical layer convergence protocol (PLCP) protocol data units (PPDUs) and medium access control (MAC) protocol data units (MPDUs) in compliance with the IEEE 802.11 wireless communication protocol standards (such as the standards 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).

[0058] The wireless communication device 400 may be or may include the following: a chip, a system on chip (SoC), a chipset, a package, or a device including one or more modems 402 (e.g., a Wi-Fi (IEEE 802.11 compliant) modem). In some implementations, the one or more modems 402 (collectively referred to as "modems 402") additionally include a WWAN modem (e.g., a 3GPP 4G LTE or 5G compliant modem). In some implementations, the wireless communication device 400 also includes one or more radio units 404 (collectively referred to as "radio units 404"). In some implementations, the wireless communication device 406 also includes one or more processors, processing blocks, or processing elements 406 (collectively referred to as "processors 406") and one or more storage blocks or elements 408 (collectively referred to as "memory 408").

[0059] The modem 402 may include an intelligent hardware block or device, such as, for example, an application specific integrated circuit (ASIC) and other possibilities. The modem 402 is typically configured to implement the PHY layer. For example, the modem 402 is configured to modulate packets and output the modulated packets to the radio unit 404 for transmission on a wireless medium. The modem 402 is similarly configured to obtain modulated packets received by the radio unit 404, and demodulate the packets to provide demodulated packets. In addition to the modulator and demodulator, the modem 402 may also include digital signal processing (DSP) circuits, automatic gain control (AGC), encoders, decoders, multiplexers, and demultiplexers. For example, when in transmission mode, data obtained from the processor 406 is provided to an encoder, which encodes the data to provide encoded bits. The encoded bits are then mapped to points in a modulation constellation (using a selected MCS) to provide modulated symbols. The modulated symbols can then be mapped to a number (N SS ) spatial streams or a number (N STS ) space-time streams. The modulated symbols in the respective spatial streams or space-time streams may then be multiplexed, transformed via an Inverse Fast Fourier Transform (IFFT) block, and subsequently provided to a DSP circuit 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 a frequency up-converter, and ultimately to a radio unit 404. In an implementation involving beamforming, the modulated symbols in the respective spatial streams are precoded via a steering matrix before providing them to the IFFT block.

[0060] When in receive mode, a digital signal received from the radio unit 404 may be provided to a DSP circuit configured to acquire the received signal, for example, by detecting the presence of a signal and estimating an initial timing and frequency offset. The DSP circuit is also 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 obtain a narrowband signal. The output of the DSP circuit may then be fed to an AGC configured to determine an appropriate gain using information extracted from the digital signal (e.g., in one or more received training fields). The output of the DSP circuit is also coupled to a demodulator 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, which may be configured to process the LLRs to provide decoded bits. The decoded bits from all spatial streams are then fed to a demultiplexer for demultiplexing. The demultiplexed bits may then be descrambled and provided to the MAC layer (processor 406) for processing, evaluation, or interpretation.

[0061] The radio unit 404 typically includes at least one radio frequency (RF) transmitter (or "transmitter chain") and at least one RF receiver (or "receiver chain"), which may be combined into one or more transceivers. For example, the RF transmitter and receiver may include various DSP circuits 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 400 may include or be coupled to multiple transmit antennas (each with a corresponding transmit chain) and multiple receive antennas (each with a corresponding receive chain). The symbols output from the modem 402 are provided to the radio unit 404, which then transmits the symbols via the coupled antennas. Similarly, the symbols received via the antennas are obtained by the radio unit 404, which then provides the symbols to the modem 402.

[0062] The processor 406 may include an intelligent hardware block or device designed to perform the functions described herein, such as 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 406 processes information received through the radio unit 404 and the modem 402, and processes information to be output by the modem 402 and the radio unit 404 for transmission over a wireless medium. For example, the processor 406 can 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 406 can generally control the modem 402 so that the modem performs the various operations described above.

[0063] The memory 408 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 408 may also store non-transitory processor or computer executable software (SW) code containing instructions that, when executed by the processor 406, 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, various functions of the components disclosed herein or 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.

[0064] Figure 5A A block diagram of an example AP 502 is shown. For example, the AP 502 may be a reference Figure 1 1. An example implementation of AP 102 is described. AP 502 includes a wireless communication device (WCD) 510 (although AP 502 itself may also be generally referred to as a wireless communication device as used herein). For example, wireless communication device 510 may be a wireless communication device (WCD) 510. Figure 4An example implementation of the wireless communication device 400 described herein. The AP 502 also includes a plurality of antennas 520 coupled to the wireless communication device 510 to send and receive wireless communications. In some implementations, the AP 502 further includes an application processor 530 coupled to the wireless communication device 510 and a memory 540 coupled to the application processor 530. The AP 502 also includes at least one external network interface 550 that enables the AP 502 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 550 may include one or both of a wired (e.g., Ethernet) network interface and a wireless network interface (such as a WWAN interface). Components in the aforementioned components may communicate directly or indirectly with other components in the components on at least one bus. The AP 502 also includes a housing that surrounds the wireless communication device 510, the application processor 530, the memory 540, and at least portions of the antenna 520 and the external network interface 550.

[0065] Figure 5B A block diagram of an example STA 504 is shown. For example, STA 504 may be a reference Figure 1 104. STA 504 includes a wireless communication device 515 (although STA 504 itself may also be generally referred to as a wireless communication device as used herein). For example, wireless communication device 515 may be a wireless communication device as described herein. Figure 4 5. The STA 504 also includes one or more antennas 525 coupled to the wireless communication device 515 to send and receive wireless communications. The STA 504 further includes an application processor 535 coupled to the wireless communication device 515 and a memory 545 coupled to the application processor 535. In some implementations, the STA 504 also includes a user interface (UI) 555 (such as a touch screen or keyboard) and a display 565, which can be integrated with the UI 555 to form a touch screen display. In some implementations, the STA 504 can also include one or more sensors 575, such as one or more inertial sensors, accelerometers, temperature sensors, pressure sensors, or altitude sensors. Components in the aforementioned components can communicate directly or indirectly with other components in the components on at least one bus. The STA 504 also includes a housing that surrounds the wireless communication device 515, the application processor 535, the memory 545, and at least portions of the antenna 525, the UI 555, and the display 565.

[0066] As described above, wireless communications in some frequency bands (such as the 6 GHz band) are subject to power spectral density (PSD) limits. When wireless signals are transmitted via multiple antennas (such as an antenna array), the energy radiated in any given direction must not exceed the PSD limit of the wireless channel. The directional gain of the wireless transmission is equal to the gain of each antenna plus any array gain that may be generated when the signals sent on different antennas are positively correlated in a particular direction (such as in a beamformed transmission or an open-loop transmission that results in unintentional beamforming). If the same digital data is sent via two or more antennas in a given symbol period (even with different encoding or phase shifts), the wireless signal is "correlated". Therefore, correlated signals may exist at any frequency or time delay. Aspects of the present disclosure recognize that the power penalty associated with open-loop transmission can be reduced by avoiding the transmission of correlated signals.

[0067] Various aspects are generally directed to improving wireless communications in PSD limited frequency bands, and more particularly, to reducing the power penalty associated with open loop transmission in PSD limited frequency bands. TX ) transmit antennas can parse the PPDU into a number (N SS ) spatial streams, and N SS spatial streams (where N SS ≥1) is modulated onto a number (M) of subcarriers. In some aspects, the wireless communication device may map the M subcarriers to a number (N) of transmit antennas, where N SS ≤N <N TX , and the PPDU can be sent to the receiving device based on the mapping of the M subcarriers to the N transmit antennas. More specifically, the wireless communication device can send N SS In some other aspects, the wireless communication device may subdivide the M subcarriers into two or more groups, and may map each subcarrier group to N TX The number of transmit antennas mapped to each subcarrier group is greater than or equal to the number of spatial streams modulated onto the subcarriers in the group, but less than N. TX In such an aspect, the wireless communication device may transmit the PPDU based on the mapping of subcarrier groups to transmit antenna subsets. More specifically, the wireless communication device may transmit the spatial streams associated with each subcarrier group using only the transmit antennas mapped to the subcarrier group.

[0068] Specific implementations of the subject matter described in the present disclosure may achieve one or more of the following potential advantages. Implementations herein may reduce the power penalty associated with open-loop transmission in a PSD-limited band by reducing or eliminating the transmission of correlated signals. Various aspects of the present disclosure may reduce the number of correlated signals associated with open-loop transmission (compared to existing open-loop transmission techniques) by using some but not all of the available transmit antennas to transmit any number of spatial streams. For example, by mapping a PPDU to a number of transmit antennas (N=N) that is equal to the number of spatial streams associated with the PPDU. SS ), the wireless communication device can send N unrelated signals via N transmitting antennas respectively (where N <N TX Additionally or alternatively, by mapping different groups of subcarriers (modulated with different portions of the PPDU) to different subsets of transmit antennas, aspects of the present disclosure may decorrelate the signals sent by each antenna (and, therefore, compare the signals transmitted by each antenna to the N antennas where the PPDU as a whole is mapped to the N antennas). SS ≤N <N TX Compared with the implementation of multiple antennas, a larger number of available transmit antennas can be used for open-loop transmission. For example, by subdividing M subcarriers into N TX subcarrier groups, the wireless communication device can respectively TX antennas to transmit N TX Such techniques for reducing the power penalty associated with open-loop transmission can be used to increase the range of wireless communications, as well as improve packet detection and channel estimation capabilities of wireless communication devices in PSD-limited frequency bands.

[0069] Figure 6 A block diagram of an example transmitter 600 for a wireless communication device according to some implementations is shown. In some aspects, the wireless communication device may be Figure 4 The transmitter 600 includes a stream parser 610, a constellation mapper 620(1)-620(N SS )、OFDM modulator 630(1)–630(N SS ), PSD mapper 640 and are respectively coupled to a number (N TX ) transmit (TX) antennas 660(1)–660(N TX ) of TX chain 650(1)–650(N TX In some aspects, transmitter 600 may be configured to process PPDU 601 for transmission via TX antennas 660(1)-660(N TX ) for transmission.

[0070] The stream parser 610 parses the PPDU 601 into a number (N SS ) spatial streams 602(1)–602(N SS In some aspects, the number of spatial streams may be equal to one (N SS =1). In some other aspects, the number of spatial streams may be greater than one (N SS >1). In such an aspect, spatial streams 602(1)-602(N SS Each of the constellation mappers 620(1)-620(N) may include a different (non-overlapping) portion of the data in the payload of the PPDU 601. SS ) spatial streams 602(1)-602(N) according to the modulation scheme SS ) are mapped to frequency domain (FD) symbols 603(1)–603(N SS ). Example suitable modulation schemes include binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), and quadrature amplitude modulation (QAM), among other examples. OFDM modulators 630(1)-630(N SS )FD symbols 603(1)–603(N SS ) are modulated to orthogonal subcarriers 604(1)–604(N SS More specifically, OFDM modulators 630(1)-630(N SS ) can each of FD symbols 603(1)–603(N SS ) are modulated onto a number (M) of subcarriers spanning a bandwidth associated with the wireless channel.

[0071] In some aspects, the PSD mapper 640 may be configured to map the modulated subcarriers 604(1)-604(N) based on a PSD limit associated with the wireless channel. SS ) are mapped to TX antennas 660(1)–660(N TX ) . In some implementations, when operating in a PSD limited band (such as a 6 GHz LPI channel), mapping can reduce the number of correlated signals sent by transmitter 600. Aspects of the present disclosure recognize that the number of correlated signals can be reduced by eliminating or avoiding repeated transmissions of the same data via multiple TX antennas. Aspects of the present disclosure also recognize that since different spatial streams carry different (uncorrelated) data, spatial streams 602(1)-602(N) may be used to transmit the same data to the same spatial streams. SS ) can be via N SSTX antennas without incurring array gain (as defined by the PSD limit). Thus, in some aspects, the PSD mapper 640 may map the modulated subcarriers 604(1)-604(N SS ) is mapped to a number (N) of TX antennas 660(1)-660(N) that is at least equal to the number of spatial streams but less than the total number of available TX antennas (N SS ≤N <N TX ).

[0072] In some implementations, the PSD mapper 640 may map the modulated subcarriers 604(1)-604(N SS ) is mapped to each TX antenna (N = N SS ) so that no duplicate data is sent from TX antennas 660(1)-660(N). For example, PSD mapper 640 may map modulated subcarriers 604(1)-604(N) to SS ) are provided directly to TX chains 650(1)-650(N) coupled to TX antennas 660(1)-660(N) as decorrelated subcarriers 605. In such an implementation, PSD mapper 640 may optimize the transmit power for open-loop transmission (such as by avoiding any transmission of correlated signals), but may sacrifice some spatial diversity (due to the unused TX antennas).

[0073] In some other implementations, the PSD mapper 640 may map the modulated subcarriers 604(1)-604(N SS ) is mapped to multiple TX antennas (N>N SS ), so that some repetitive data is transmitted from TX antennas 660(1)-660(N). For example, PSD mapper 640 may apply STBC or a precoding matrix to modulated subcarriers 604(1)-604(N). SS ) to produce decorrelated subcarriers 605. In such an implementation, the PSD mapper 640 can achieve greater spatial diversity (with N = N) by sacrificing some gain in transmit power for open-loop transmission. SS compared to the implementation method of ).

[0074] exist Figure 6 In the example of FIG. 1 , the modulated subcarriers 604 ( 1 )–604 (N SS ) is depicted as being mapped to the first N TX antennas of the antenna array (such as TX antennas indexed 1-N). However, in actual implementations, the PSD mapper 640 may map the modulated subcarriers 604(1)-604(N SS) are mapped to any combination or subset of the N TX antennas in the antenna array. In some aspects, the PSD mapper 640 may randomly select the modulated subcarriers 604(1)-604(N SS ) is mapped to the TX antenna. In some other aspects, the PSD mapper 640 may determine the subcarriers to be mapped to the modulated subcarriers 604(1)-604(N) based on a lookup table (or some predetermined process). SS )’s TX antenna.

[0075] In some implementations, the lookup table may indicate the TX antennas 660(1)-660(N TX ) to be used to transmit any given number of spatial streams. In such an implementation, the PSD mapper 640 may determine the number of spatial streams N associated with the PPDU 601 based on the number of spatial streams N associated with the PPDU 601. SS In some other implementations, a lookup table may be used to store and use TX antennas 660(1)-660(N TX ). Example historical data may include historical data associated with previous transmissions of various combinations of TX antennas 660(1)-660(N TX ), and other examples. In such an implementation, the PSD mapper 640 can select the TX antenna that is expected to optimize the processing SNR (or SINR) or spatial diversity based on historical data stored by the lookup table.

[0076] In some other aspects, the PSD mapper 640 may receive feedback 606 from a receiving device (such as any device receiving an open-loop transmission from the transmitter 600), and may select the subcarriers to be mapped to the modulated subcarriers 604(1)-604(N) based on the received feedback 606. SS ) of the TX antenna 660(1)-660(N). In some aspects, the feedback 606 may include channel state information (CSI) associated with the wireless channel. In some implementations, the selected TX antenna 660(1)-660(N) may produce the highest processed SNR (or SINR) indicated by the received CSI. In some other implementations, the selected TX antenna 660(1)-660(N) may be associated with the highest channel gain indicated by the received CSI.

[0077] In some other implementations, one of the selected TX antennas 660(1)-660(N) may be associated with the highest channel gain indicated by the received CSI, and the remaining N-1 TX antennas may be selected based on their degree of correlation with the other TX antennas in the TX antennas 660(1)-660(N). For example, if N=3, the PSD mapper 640 may select the TX antennas 660(1)-660(N) from the PSD mapper 640. TX ) selects the first TX antenna with the highest channel gain indicated by the received CSI; the TX antennas 660(1)-660(N TX ) selects a second TX antenna having the lowest correlation with the first TX antenna among the TX antennas 660(1)-660(N TX ) selects a third TX antenna having the lowest correlation with the first TX antenna and the second TX antenna.

[0078] In some other implementations, one of the selected TX antennas 660(1)-660(N) may be associated with the highest channel gain indicated by the received CSI, and the remaining N-1 TX antennas may be selected based on their associated channel gains in directions orthogonal to the other antennas in the TX antennas 660(1)-660(N). For example, if N=3, the PSD mapper 640 may select the TX antennas 660(1)-660(N) from the PSD mapper 640. TX ) may select a first TX antenna having a highest channel gain indicated by the received CSI; may select a second TX antenna having a highest channel gain indicated by the CSI in a direction orthogonal to the first TX antenna; and may select a third TX antenna having a highest channel gain indicated by the CSI in a direction orthogonal to the first TX antenna and the second TX antenna.

[0079] In some other aspects, the feedback 606 may identify the TX antennas 660(1)-660(N) to be used to transmit the PPDU 601. In other words, the receiving device may indicate or suggest how the modulated subcarriers 604(1)-604(N) should be transmitted. SS ) are mapped to TX antennas 660(1)-660(N). In some implementations, the receiving device may select TX antennas 660(1)-660(N) based on CSI associated with the wireless channel (such as by using any of the antenna selection criteria described above). For example, the receiving device may perform an antenna selection operation (that would otherwise be performed by PSD mapper 640) based on CSI obtained from a previous open-loop transmission by transmitter 600.

[0080] TX chain 650(1)–650(NTX ) are configured to process the modulated subcarriers for transmitting signals via TX antennas 660(1)-660(N) respectively. TX ) for transmission. More specifically, TX chains 650(1)–650(N TX ) can each process a respective subset of the decorrelated subcarriers 605 based on the mapping performed by the PSD mapper 640. Example processing may include converting the frequency domain subcarriers to time domain samples (such as via an inverse fast Fourier transform (IFFT)), adding a cyclic prefix to the time domain samples, converting the time domain samples to a time-varying signal (such as via a digital-to-analog converter (DAC)), up-converting the time-varying signal to a radio frequency (RF) signal (such as by mixing the time-varying signal with a signal or waveform oscillating at a carrier frequency), and amplifying the power of the RF signal (such as via a power amplifier), among other examples.

[0081] In some aspects, the transmitter 600 may include Figure 6 For example, the transmitter 600 may also include a forward error correction (FEC) encoder that encodes the PPDU 601 to enable error detection (and correction) at the receiving device. More specifically, the FEC may be a decoder that decodes the PPDU 601 into spatial streams 602(1)-602(N). SS ) is performed before. Example suitable FEC encoders include low density parity check (LDPC) encoders and binary convolutional code (BCC) encoders, among other examples. When PPDU 601 is BCC encoded, transmitter 600 may also include N SS interleavers, which respectively perform operations on spatial streams 602(1)–602(N SS ) to prevent long sequences of adjacent noisy bits from entering the BCC decoder (at the receiving device).

[0082] Figure 7 A frequency diagram depicting an example mapping of a PPDU 700 to a subset of TX antennas according to some implementations is shown. In some aspects, the mapping may avoid correlated signals in open loop transmissions. In some implementations, the mapping may be performed by Figure 6 The PSD mapper 640 is used to perform the Figure 7 In the example of FIG. 7 , PPDU 700 is shown as including a single spatial stream (N ) modulated onto a set of subcarriers 710 that span a bandwidth associated with a wireless channel (also referred to as a “PPDU bandwidth”). SS =1). Figure 6 As described, the correlation signal may be obtained by mapping the modulated subcarriers 710 to a number (N) of TX antennas (N=N) equal to the number of spatial streams. SS). Because PPDU 700 includes only a single spatial stream, the open-loop transmit power of PPDU 700 can be optimized by mapping the modulated subcarrier 710 to a single TX antenna (ANT_1). Figure 6 TX antenna ANT_1 may be TX antenna 660(1)–660(N TX ) any TX antenna.

[0083] exist Figure 7 The mapping shown in reduces the power penalty associated with open loop transmission in a PSD limited band. As a result, PPDU 700 can be transmitted with a higher transmission power compared to existing open loop transmission techniques. For example, PPDU 700 can be transmitted in the 6 GHz (LPI) band using 1 TX antenna with a total conducted power of up to 30 dBm (compared to 24 dBm using 4 TX antennas), which represents a 6 dB increase in transmit power. However, in order to achieve such a gain in transmit power, the power amplifier coupled to TX antenna ANT_1 may need to support a higher output power. Further, in Figure 7 The mapping shown in does not benefit from any spatial diversity associated with having multiple TX antennas. Aspects of the present disclosure recognize that because each of the modulated subcarriers 710 carries different (uncorrelated) data, the wireless communication device can achieve spatial diversity in open-loop transmissions by mapping different subsets or groups of the modulated subcarriers 710 to different TX antennas without incurring any additional power penalty.

[0084] Figure 8 Another frequency diagram depicting an example mapping of a PPDU 800 to a subset of transmit antennas according to some implementations is shown. In some aspects, the mapping may avoid correlated signals in open loop transmissions. In some implementations, the PPDU 800 may be Figure 7 More specifically, PPDU 800 may include a single spatial stream modulated onto a set of subcarriers that span the PPDU bandwidth. Figure 8 In the example of G ) groups 810(1)–810(N G ), so that each group includes one or more of the modulated subcarriers. In some aspects, subcarrier groups 810(1)-810(N G) may overlap with respective (non-overlapping) portions of the PPDU bandwidth. In other words, subcarriers belonging to group 810(1) are unique to group 810(1), subcarriers belonging to group 810(2) are unique to group 810(2), and subcarriers belonging to group 810(N) are unique to group 810(N). G ) for the subcarriers of group 810 (N G For example, subcarrier groups 810(1)–810(N G Each subcarrier group in ) may be associated with a different resource unit (RU) or subband of the PPDU bandwidth (such as defined by existing versions of the IEEE 802.11 standard). In some implementations, subcarrier groups 810(1)-810(N) may be associated with a different resource unit (RU) or subband of the PPDU bandwidth (such as defined by existing versions of the IEEE 802.11 standard). G ) may include the same number of modulated subcarriers. In some other implementations, subcarrier groups 810(1)-810(N G ) may include fewer or more modulated subcarriers than other groups.

[0085] In some implementations, each subcarrier group 810(1)-810(N G ) can be mapped to their respective TX antennas (ANT_1–ANT_N G Since each modulated subcarrier group 810(1)-810(N G ) carry different (unrelated) data, so for subcarrier groups 810(1)–810(N G ) to TX antennas ANT_1–ANT_N respectively G The mapping of does not cause array gain (as defined by the PSD limit) in the open loop transmission. Figure 7 Compared to the example mapping in Figure 8 The mapping shown in can utilize a greater number of TX antennas to transmit the same number of spatial streams (without additional power penalty), and thus can achieve greater spatial diversity in open-loop transmission. For example, when the number of subcarrier groups is equal to the total number of available TX antennas (N G =N TX ), the PPDU 800 may be sent using all available TX antennas. In some aspects, Figure 8 The example mapping of can be extended to multiple spatial streams. In such an aspect, each subcarrier group 810(1)-810(N G ) may be based on the number of spatial streams modulated onto the subcarriers in the group (N SS ) and the total number of available TX antennas (N TX ) to their respective number (K) of TX antennas, where N SS ≤K <NTX .

[0086] Aspects of the present disclosure recognize that the tone schedule associated with existing versions of the IEEE 802.11 standard requires that guard subcarriers (which are empty) be inserted at the edges or boundaries of various subbands. A receiving device may fill in guard subcarriers at some subband boundaries to simulate a continuous channel (referred to as "channel smoothing"). However, each subcarrier group 810(1)-810(N) is not necessarily a subcarrier group. G ) are mapped to different TX antennas resulting in each subcarrier group 810(1)–810(N G ) will be transmitted on respective wireless channels. For example, the first modulated subcarrier group 810(1) and the second modulated subcarrier group 810(2) may not be transmitted on the same contiguous channel. As a result, channel smoothing at the boundary between the first subcarrier group 810(1) and the second subcarrier group 810(2) may result in errors in the received signal. In some aspects, the subcarrier groups 810(1)–810(N G ) can be configured to avoid channel smoothing at group boundaries. Aspects of the present disclosure recognize that existing wireless communication devices do not perform channel smoothing at 80 MHz subband boundaries. In some implementations, each modulated subcarrier group 810(1)-810(N G ) can overlap with their respective 80MHz sub-bands.

[0087] Fig. 9 Another block diagram of an example transmitter 900 for a wireless communication device according to some implementations is shown. In some aspects, the wireless communication device may be Figure 4 The transmitter 900 includes a stream parser 910, a constellation mapper 920(1)-920(N SS )、OFDM modulators 930(1)–930(N SS ), a bandwidth (BW) parser 940, a PSD mapper 950, and a number (N) of TX ) TX antennas 970(1)–970(N TX ) of TX chain 960(1)–960(N TX In some aspects, transmitter 900 may be configured to process PPDU 901 for transmission via TX antennas 970(1)-970(N TX ) for transmission.

[0088] The stream parser 910 parses the PPDU 901 into a number (N SS ) spatial streams 902(1)–902(N SSIn some aspects, the number of spatial streams may be equal to one (N SS =1). In some other aspects, the number of spatial streams may be greater than one (N SS >1). In such an aspect, spatial streams 902(1)-902(N SS ) may include a different (non-overlapping) portion of the data in the payload of PPDU 901. Constellation mappers 920(1)-920(N SS ) spatial streams 902(1)-902(N) according to the modulation scheme SS ) are mapped to frequency domain symbols 903(1)–903(N SS ). Example suitable modulation schemes include BPSK, QPSK, and QAM, among other examples. OFDM modulators 930(1)-930(N SS ) frequency domain symbols 903(1)–903(N SS ) are modulated to orthogonal subcarriers 904(1)–904(N SS More specifically, OFDM modulators 930(1)-930(N SS ) can each of the symbols 903(1)–903(N SS ) are modulated onto a number (M) of subcarriers spanning a bandwidth associated with the wireless channel.

[0089] In some aspects, the BW parser 940 may subdivide the M subcarriers into a number (N G ) subcarrier groups 905 (such as reference Figure 8 905). In some implementations, the subcarriers in each of the subcarrier groups 905 may represent respective (non-overlapping) portions of the PPDU bandwidth. In some implementations, each of the subcarrier groups in the subcarrier groups 905 may be associated with a respective RU or multiple RUs (M-RUs). In some other implementations, each of the subcarrier groups in the subcarrier groups 905 may be associated with a respective subband of the PPDU bandwidth. In some implementations, the subbands may be configured to avoid channel smoothing between subcarrier group boundaries (such as with reference to Figure 8 905). In some implementations, each subcarrier group in subcarrier group 905 may include the same number of modulated subcarriers. For example, each subcarrier group in subcarrier group 905 may be associated with the same RU or subband size. In some other implementations, at least one subcarrier group in subcarrier group 905 may include a different number of subcarriers than any subcarrier group in the remaining subcarrier groups. For example, subcarrier group 905 may be associated with different RU or subband sizes.

[0090] In some aspects, PSD mapper 950 may be configured to map each of subcarrier groups 905 to TX antennas 970(1)-970(N) based on a PSD limit associated with a wireless channel. TX ). For example, mapping may reduce the number of correlated signals sent by transmitter 900 when operating in a PSD limited frequency band, such as a 6 GHz LPI channel. In some aspects, PSD mapper 950 may map each of subcarrier groups 905 to a respective number (K) of TX antennas that is at least equal to the number of spatial streams (N) modulated onto the subcarriers in the group. SS '≤N SS ), but is less than the total number of available TX antennas (N SS '≤K <N TX ). In some aspects, the PSD mapper 950 may randomly select a TX antenna to which the subcarrier group 905 is mapped. In some other aspects, the PSD mapper 950 may determine the TX antenna to be mapped to the subcarrier group 905 based on a lookup table (or some predetermined process). Further, in some aspects, the PSD mapper 950 may receive feedback 907 from a receiving device, and may select the TX antenna to be mapped to the subcarrier group 905 based on the received feedback 907. In some implementations, the feedback 907 may include CSI associated with one or more of the subcarrier groups 905. In some other implementations, the feedback 907 may include an indication of the TX antenna to be mapped to the subcarrier group 905.

[0091] exist Fig. 9 In the example of FIG. 1 , subcarrier group 905 is shown as being mapped to all available TX antennas 970(1)-970(N TX However, in actual implementation, PSD mapper 950 may map subcarrier group 905 to TX antennas 970(1)-970(N TX ). The PSD mapper 950 provides signals coupled to TX antennas 970(1)-970(N) based on the mapping. TX ) of TX chain 960(1)–960(N TX ) provides a set of decorrelated subcarriers 906. Figure 6 As depicted, decorrelated subcarriers 906 may include modulated subcarriers 904(1)-904(N SS ) (depending on whether STBC or a precoding matrix is ​​used when mapping any subcarrier group in subcarrier groups 905 to respective TX antenna subsets). The total number of TX antennas (N) used to transmit PPDU 901 may depend on the total number of subcarrier groups 905 (N G) and the TX antenna to which each subcarrier group is mapped. Figure 8 As described, PPDU 901 may be a packet that uses at least N G TX antennas (N≥N G ) is sent. By subdividing M subcarriers into N TX Subcarrier groups 905 (N G =N TX ), the BW parser 940 can ensure that all available TX antennas are utilized for open-loop transmission (N=N TX ).

[0092] TX chain 960(1)–960(N TX ) are configured to process the modulated subcarriers into RF signals for transmission via TX antennas 970(1)-970(N) respectively. TX More specifically, TX chains 960(1)–960(N TX ) can process a respective subset of the decorrelated subcarriers 906 based on the mapping performed by the PSD mapper 950. Example processing may include converting the frequency domain subcarriers to time domain samples (such as via an IFFT), adding a cyclic prefix to the time domain samples, converting the time domain samples to a time-varying signal (such as via a DAC), up-converting the time-varying signal to an RF signal (such as by mixing the time-varying signal with a signal or waveform oscillating at a carrier frequency), and amplifying the power of the RF signal (such as via a power amplifier), among other examples.

[0093] Fig.10 A block diagram of an example antenna switching system 1000 according to some implementations is shown. In some implementations, the antenna switching system 1000 may be Fig. 9 Thus, the antenna switching system 1000 can be configured to convert a number (N G ) subcarrier groups 1002(1)–1002(N G ) is mapped to a number (N) of TX antennas. For example, refer to Fig. 9 , subcarrier groups 1002(1)–1002(N G ) may be an example of subcarrier group 905. Antenna switching system 1000 includes N G Subband mappers 1010(1)–1010(N G ) and multiplexer 1020.

[0094] Subband mappers 1010(1)–1010(N G) are configured to map a respective subcarrier group to one or more of the TX antennas. In some implementations, the subband mappers 1010(1)-1010(N G ) can be Figure 6 For example, the subband mapper 1010(1) may be based on the total number of available TX antennas (N TX ) and the number of spatial streams modulated onto subcarrier 1002(1) (N SS1 ) to map subcarrier 1002(1) to a number (K) of TX antennas, where N SS1 ≤K <N TX Similarly, the subband mapper 1010 (N G ) can be based on N TX and modulated to subcarrier 1002 (N G ) on the number of spatial streams (N SS2 ) to convert subcarrier 1002 (N G ) is mapped to a number (L) of TX antennas, where N SS2 ≤L <N TX .

[0095] Subband mappers 1010(1)–1010(N G ) can be based on the subcarriers 1002(1)–1002(N G ) associated mapping to generate decorrelated subcarriers 1004(1)-1004(N G For example, subband mapper 1010(1) may transform subcarrier 1002(1) into K sets of decorrelated subcarriers 1004(1), and subband mapper 1010(N G ) can be subcarrier 1002 (N G ) is transformed into decorrelated subcarriers 1004 (N G ). In some implementations, the decorrelated subcarriers 1004(1)–1004(N G ) may not include modulation to subcarriers 1002(1)–1002(N G ) in the data (such as where K = N SS1 And L = N SS2 In some other implementations, the decorrelated subcarriers 1004(1)-1004(N G ) may include modulation onto subcarriers 1002(1)–1002(N G ) (such as where K>N SS1 or L>N SS2 ).

[0096] In some aspects, subband mappers 1010(1)-1010(N G ) can randomly select subcarriers 1002(1)–1002(N G ) is mapped to the TX antenna. In some other aspects, the subband mappers 1010(1)-1010(N G ) may determine the subcarriers 1002(1)-1002(N) to be mapped based on a lookup table (or some predetermined process). G ) of the TX antennas. In some implementations, the lookup table may indicate which of the TX antennas are to be used to transmit any given number of spatial streams. In some other implementations, the lookup table may store historical data associated with previous transmissions using various combinations of TX antennas. Example historical data may include SNR or SINR associated with any subset or combination of available TX antennas, as well as other examples.

[0097] In some other aspects, subband mappers 1010(1)-1010(N G ) can receive feedback 1006(1)-1006(N) from the receiving device respectively G ), and the subcarriers 1002(1)-1002(N) to be mapped may be selected based on the received feedback. G ) of the TX antenna. In some implementations, feedback 1006(1)-1006(N G ) may identify the subcarrier groups 1002(1)–1002(N) to be mapped to each subcarrier group G ) of the TX antenna. In some other implementations, feedback 1006(1)-1006(N G ) may include subcarriers 1002(1)–1002(N G ) associated CSI. In some implementations, subband mappers 1010(1)-1010(N G ) can select the TX antenna that results in the highest processed SNR (or SINR) indicated by its received CSI. In some other implementations, subband mappers 1010(1)-1010(N) may each select the TX antenna that results in the highest processed SNR (or SINR) indicated by its received CSI. G ) can select the TX antenna associated with the highest channel gain indicated by the CSI received by it.

[0098] In some other implementations, subband mappers 1010(1)-1010(N G) may each select at least the TX antenna associated with the highest channel gain indicated by the CSI received therethrough, and any remaining TX antennas may be selected based on their degree of correlation with the other selected TX antennas (such as with reference to Figure 6 Furthermore, in some implementations, subband mappers 1010(1)-1010(N G ) may each select at least the TX antenna associated with the highest channel gain indicated by the received CSI, and any remaining TX antennas may be selected based on their associated channel gains in directions orthogonal to the other selected TX antennas (such as with reference to Figure 6 described).

[0099] In some other aspects, subband mappers 1010(1)-1010(N G ) may select the subcarriers to be mapped to subcarrier groups 1002(1)-1002(N) based on any combination of the factors described above. G ) TX antennas. For example, subband mapper 1010(1) may select K TX antennas to be mapped to subcarriers 1002(1) based on a lookup table or a random process, and subband mapper 1010(N G ) may be based on feedback 1006 (N received from a receiving device G ) to select the subcarrier 1002 (N G ) of L TX antennas. In some implementations, subband mappers 1010(1)-1010(N G ) can be respectively utilized by feedback 1006(1)–1006(N G ) is used to perform antenna selection (whenever such feedback is available). In other words, when feedback is not available for its subcarrier group, subband mappers 1010(1)-1010(N G ) can utilize a lookup table or a random process for antenna selection.

[0100] Multiplexer 1020 multiplexes decorrelated subcarriers 1004(1)-1004(N G ) multiplexed to N TX chains (such as Fig. 9 TX chain 960(1)–960(N TX) to be processed and transmitted via the N selected TX antennas, respectively. For example, the multiplexer 1020 can output the K sets of decorrelated subcarriers 1004(1) to the K TX chains out of the N TX chains, respectively, based on the mapping performed by the subband mapper 1010(1). More specifically, the K TX chains can be coupled to the K TX antennas selected by the subband mapper 1010(1). Similarly, the multiplexer 1020 can output the K sets of decorrelated subcarriers 1004(1) to the K TX chains out of the N TX chains, respectively. G ) is performed to map the decorrelated subcarriers 1004 (N G ) are respectively output to L TX chains among the N TX chains. More specifically, the L TX chains may be coupled to the subband mapper 1010 (N G )Selected L TX antennas.

[0101] As reference Figure 8 As described, mapping different subcarrier groups to different TX antennas causes each subcarrier group to be transmitted on a different wireless channel. As a result, channel smoothing between subcarrier group boundaries may cause errors at the receiving device. In some implementations, subband mappers 1010(1)-1010(N G ) can be respectively assigned to subcarrier groups 1002(1)–1002(N G ) to ensure coarse phase and amplitude continuity at subband boundaries (such as to compensate for channel smoothing at the receiving device). For example, subband mapper 1010(1) may determine the phase rotation (if any) to apply to subcarrier 1002(1) based on channel information included in feedback 1006(1) (or implicitly measured). Similarly, subband mapper 1010(N) may also add phase rotation or overlap and add (OLA) to ensure coarse phase and amplitude continuity at subband boundaries (such as to compensate for channel smoothing at the receiving device). G ) may be based on the information included in feedback 1006 (N G ) in (or implicitly measured) channel information to determine the channel information to be applied to subcarrier 1002 (N G )'s phase rotation (if any).

[0102] In some aspects, the transmitter 900 may include Fig. 9 For example, the transmitter 900 may also include an FEC encoder that encodes the PPDU 901 to enable error detection (and correction) at the receiving device. More specifically, the FEC may be a decoder that decodes the PPDU 901 into spatial streams 902(1)-902(N). SS ) is performed before. Example suitable FEC encoders include LDPC encoders and BCC encoders, among other examples. When PPDU901 is BCC encoded, transmitter 900 may also include NSS interleaver, N SS The interleavers are respectively used for spatial streams 902(1)–902(N SS ) to prevent long sequences of adjacent noisy bits from entering the BCC decoder (at the receiving device).

[0103] Fig.11 A flow chart illustrating an example process 1100 for supporting wireless communications with antenna switching in a frequency band with PSD limitations is shown. In some aspects, process 1100 may be performed as a number (N) of TX ) transmit antennas (such as those described above, respectively, Figure 1 and Figure 5A Any of the APs 102 or 502 described herein) operates or has a number (N TX ) transmit antennas (such as those described above, respectively, Figure 1 and Figure 5A In some other aspects, process 1100 may be performed by a wireless communication device operating within any of APs 102 or 502 described herein. TX STAs with multiple transmit antennas (such as those described above, respectively) Figure 1 and Figure 5B Any STA in STA104 or 504 described herein) operates or has N TX STAs with multiple transmit antennas (such as those described above, respectively) Figure 1 and Figure 5B The method may be performed by a wireless communication device operating within any STA 104 or 504 described herein.

[0104] In some implementations, process 1100 begins at block 1102, where a PPDU is parsed into a number (N SS ) spatial streams, where N SS ≥ 1. In block 1104, process 1100 continues by setting N SS The spatial streams are modulated onto a number (M) of subcarriers across a bandwidth associated with the wireless channel. In block 1106, process 1100 proceeds by mapping the M subcarriers to a number (N) of transmit antennas based on a PSD limit associated with the wireless channel, where N SS ≤N <N TX In block 1108, process 1100 continues by sending the PPDU to the receiving device via the N transmit antennas based on the mapping of the M subcarriers. In some implementations, N may be equal to N SS .

[0105] In some aspects, process 1100 may also include receiving antenna selection information indicating the N transmit antennas from the receiving device. In some other aspects, mapping the M subcarriers to the N transmit antennas may be further based on indicating that the N transmit antennas are to be used to transmit the N subcarriers. SS In some other aspects, the mapping of the M subcarriers to the N transmit antennas can be further based on a lookup table storing historical data associated with previous transmissions by the wireless communication device.

[0106] Further, in some aspects, process 1100 may also include receiving CSI from a receiving device, wherein the M subcarriers are mapped to N transmit antennas based on the received CSI. In some implementations, the N transmit antennas may be associated with the N highest SNRs or N highest SINRs indicated by the received CSI. In some implementations, the N transmit antennas may be associated with the highest channel gain indicated by the received CSI.

[0107] In some implementations, the N transmit antennas may include a first transmit antenna associated with a highest channel gain indicated by the received CSI, and a TX A second transmit antenna having the lowest correlation with the first transmit antenna among the N transmit antennas. In some implementations, the N transmit antennas may also include TX A third transmit antenna having the lowest correlation with the first transmit antenna and the second transmit antenna among the transmit antennas.

[0108] In some implementations, the N transmit antennas may include a first transmit antenna associated with a highest channel gain indicated by the received CSI and a second transmit antenna associated with a highest channel gain indicated by the received CSI in a direction orthogonal to the first transmit antenna. In some implementations, the N transmit antennas may also include a third transmit antenna having a highest channel gain indicated by the received CSI in a direction orthogonal to the first transmit antenna and the second transmit antenna.

[0109] Fig.12 A flow chart illustrating an example process 1200 for supporting wireless communications with antenna switching in a frequency band with PSD limitations is shown. In some aspects, the process 1200 may be implemented as a number (N) of TX ) transmit antennas (such as those described above, respectively, Figure 1 and Figure 5A Any of the APs 102 or 502 described herein) operates or has a number (N TX ) transmit antennas (such as those described above, respectively, Figure 1 and Figure 5AIn some other aspects, process 1200 may be performed by a wireless communication device operating within any of APs 102 or 502 described herein. TX STAs with multiple transmit antennas (such as those described above, respectively) Figure 1 and Figure 5B Any STA in STA104 or 504 described herein) operates or has N TX STAs with multiple transmit antennas (such as those described above, respectively) Figure 1 and Figure 5B The method may be performed by a wireless communication device operating within any STA 104 or 504 described herein.

[0110] In some implementations, process 1200 begins at block 1202, where a PPDU is parsed into a number (N SS ) spatial streams, where N SS ≥ 1. In block 1204, process 1200 continues by setting N SS The process 1200 continues at block 1206 by performing a step based on the number of spatial streams (N) modulated onto the first subset of the M subcarriers. SS1 ) to map the first subset of M subcarriers to a number (K) of transmit antennas, where N SS1 ≤K <N TX At block 1208, process 1200 continues by performing a step based on the number of spatial streams modulated onto the second subset of M subcarriers (N SS2 ) to map the second subset of M subcarriers to a number (L) of transmit antennas, where N SS2 ≤L <N TX In block 1210, process 1200 continues by transmitting a first portion of the PPDU to a receiving device via the K transmit antennas based on mapping to the first subset of the M subcarriers. In block 1212, process 1200 continues by transmitting a second portion of the PPDU to a receiving device via the L transmit antennas based on mapping to the second subset of the M subcarriers.

[0111] In some implementations, K may be equal to N SS1 , and L can be equal to N SS2 In some implementations, the K transmit antennas may be different from the L transmit antennas. In some implementations, the mapping of the first subset and the second subset of the M subcarriers to the K transmit antennas and the L transmit antennas, respectively, may be further based on a PSD limit associated with the wireless channel.

[0112] In some implementations, subcarriers belonging to a first subset of M subcarriers may be unique to the first subset, and subcarriers belonging to a second subset of M subcarriers may be unique to the second subset. In some implementations, the first subset of M subcarriers may represent one or more first RUs, and the second subset of M subcarriers may represent one or more second RUs. In some implementations, the first subset of M subcarriers may include a different number of subcarriers than the second subset of M subcarriers.

[0113] In some aspects, process 1200 may also include receiving antenna selection information indicating the K transmit antennas or the L transmit antennas from the receiving device. In some other aspects, mapping the first subset or the second subset of the M subcarriers to the K transmit antennas or the L transmit antennas, respectively, may be further based on indicating that the K transmit antennas are to be used to transmit the N SS1 spatial streams and L transmit antennas are used to send N SS2 In some other aspects, mapping of the first subset or the second subset of M subcarriers to the K transmit antennas or the L transmit antennas, respectively, can be further based on a lookup table storing historical data associated with previous transmissions by the wireless communication device.

[0114] Further, in some aspects, process 1200 may also include receiving CSI from a receiving device, wherein mapping of the first subset or the second subset of the M subcarriers to the K transmit antennas or the L transmit antennas, respectively, is further based on the received CSI. In some implementations, mapping of the first subset of the M subcarriers to the K transmit antennas may be based on a lookup table, and mapping of the second subset of the M subcarriers to the L transmit antennas may be based on the received CSI.

[0115] In some implementations, process 1200 may also include determining a number of spatial streams modulated onto a third subset of the M subcarriers based on the number of spatial streams (N SS3 ) to map the third subset of M subcarriers to a number (J) of transmit antennas, where N SS3 ≤J <N TX ; and sending a third part of the PPDU to the receiving device via the J transmit antennas based on the mapping of the third subset of the M subcarriers.

[0116] Fig.13 A block diagram of an example wireless communication device 1300 is shown according to some implementations. In some implementations, the wireless communication device 1300 is configured to perform a reference Fig.11 The wireless communication device 1300 may be the wireless communication device described above. Figure 4An example implementation of the wireless communication device 400 is described. For example, the wireless communication device 1300 may be a chip, SoC, chipset, package, or device including at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0117] The wireless communication device 1300 includes a receiving component 1310, a communication manager 1320, and a transmitting component 1330. The communication manager 1320 also includes a stream parsing component 1322, a subcarrier modulation component 1324, and a PSD mapping component 1326. Portions of one or more of the components 1322, 1324, and 1326 may be implemented at least in part in hardware or firmware. In some implementations, at least some of the components 1322, 1324, or 1326 are implemented at least in part as software stored in a memory, such as the memory 408. For example, portions of one or more of the components 1322, 1324, and 1326 may be implemented as non-transitory instructions (or "code") that can be executed by a processor, such as the processor 406, to perform the functions or operations of the respective components.

[0118] The receiving component 1310 is configured to receive RX signals from one or more other wireless communication devices on a wireless channel. The transmitting component 1330 is configured to transmit TX signals to one or more other wireless communication devices on a wireless channel. In some implementations, the transmitting component 1330 may include or may be coupled to a number (N) of TX ) transmit antennas. The communication manager 1320 is configured to control or manage communications with one or more other wireless communication devices. In some implementations, the stream parsing component 1322 can parse the PPDU into a number (N SS ) spatial streams, where N SS ≥1; the subcarrier modulation component 1324 can SS The spatial streams are modulated onto a number (M) of subcarriers across a bandwidth associated with a wireless channel; and a PSD mapping component 1326 can map the M subcarriers to a number (N) of transmit antennas based on a PSD limit associated with the wireless channel, where N SS ≤N <N TX In some implementations, the transmitting component 1330 can transmit the PPDU to the receiving device via the N transmit antennas based on the mapping of the M subcarriers.

[0119] Fig.14 A block diagram of an example wireless communication device 1400 is shown according to some implementations. In some implementations, the wireless communication device 1400 is configured to perform a reference Fig.11The wireless communication device 1400 may be the wireless communication device 1400 described above with reference to Figure 4 An example implementation of the wireless communication device 400 is described. For example, the wireless communication device 1400 may be a chip, SoC, chipset, package, or device including at least one processor and at least one modem (e.g., a Wi-Fi (IEEE 802.11) modem or a cellular modem).

[0120] The wireless communication device 1400 includes a receiving component 1410, a communication manager 1420, and a transmitting component 1430. The communication manager 1420 also includes a stream parsing component 1422, a subcarrier modulation component 1424, and a subband mapping component 1426. Portions of one or more of the components 1422, 1424, and 1426 may be implemented at least in part in hardware or firmware. In some implementations, at least some of the components 1422, 1424, or 1426 are implemented at least in part as software stored in a memory, such as the memory 408. For example, portions of one or more of the components 1422, 1424, and 1426 may be implemented as non-transitory instructions (or "code") that can be executed by a processor, such as the processor 406, to perform the functions or operations of the respective components.

[0121] The receiving component 1410 is configured to receive RX signals from one or more other wireless communication devices on a wireless channel. The transmitting component 1430 is configured to transmit TX signals to one or more other wireless communication devices on a wireless channel. In some implementations, the transmitting component 1430 may include or may be coupled to a number (N TX ) transmit antennas. The communication manager 1420 is configured to control or manage communications with one or more other wireless communication devices. In some implementations, the stream parsing component 1422 can parse the PPDU into a number (N SS ) spatial streams, where N SS ≥1; the subcarrier modulation component 1424 can SS The subband mapping component 1426 can be based on the number of spatial streams modulated onto the first subset of the M subcarriers (N SS1 ) to map the first subset of M subcarriers to a number (K) of transmit antennas, where N SS1 ≤K <N TX , and the number of spatial streams modulated onto the second subset of M subcarriers (N SS2 ) to map the second subset of M subcarriers to a number (L) of transmit antennas, where N SS2 ≤L <N TXIn some implementations, the transmitting component 1430 may transmit a first portion of the PPDU to the receiving device via the K transmit antennas based on the mapping of the first subset of the M subcarriers, and may transmit a second portion of the PPDU to the receiving device via the L transmit antennas based on the mapping of the second subset of the M subcarriers.

[0122] Examples of implementations are described in the following numbered clauses:

[0123] 1. A method for obtaining a number (N TX ) A method for wireless communication by a wireless communication device having a transmitting antenna, comprising:

[0124] Parse the physical layer (PHY) protocol data unit (PPDU) into a number (N SS ) spatial streams, where N SS ≥1;

[0125] N SS The spatial streams are modulated onto a number (M) of subcarriers spanning a bandwidth associated with a wireless channel;

[0126] The M subcarriers are mapped to a number (N) of transmit antennas based on a power spectral density (PSD) constraint associated with the wireless channel, where N SS ≤N <N TX ;as well as

[0127] The PPDU is transmitted to a receiving device via N transmit antennas based on the mapping to the M subcarriers.

[0128] 2. The method according to clause 1, wherein N=N SS .

[0129] 3. A method according to any of clauses 1 to 3, wherein the mapping of the M subcarriers to the N transmit antennas is further based on indicating the number of subcarriers to be used for transmitting the N SS A lookup table for N transmit antennas for N spatial streams.

[0130] 4. A method according to any of clauses 1 to 3, wherein the mapping of the M subcarriers to the N transmit antennas is further based on a look-up table storing historical data associated with previous transmissions made by the wireless communication device.

[0131] 5. A method according to any of clauses 1 to 3, further comprising:

[0132] Channel state information (CSI) is received from a receiving device, and the M subcarriers are mapped to the N transmit antennas based on the received CSI.

[0133] 6. A method according to any of clauses 1 to 3 or 5, wherein the N transmit antennas are associated with the N highest signal to noise ratios (SNRs) or the N highest signal to interference plus noise ratios (SINRs) indicated by the received CSI.

[0134] 7. A method according to any of clauses 1 to 3 or 5, wherein the N transmit antennas are associated with the highest channel gain indicated by the received CSI.

[0135] 8. A method according to any of clauses 1 to 3 or 5, wherein the N transmit antennas include a first transmit antenna associated with a highest channel gain indicated by the received CSI, and .... TX A second transmit antenna among the plurality of transmit antennas having the lowest correlation with the first transmit antenna.

[0136] 9. A method according to any of clauses 1 to 3, 5 or 8, wherein the N transmitting antennas further include TX A third transmit antenna having the lowest correlation with the first transmit antenna and the second transmit antenna among the transmit antennas.

[0137] 10. A method according to any of clauses 1 to 3 or 5, wherein the N transmit antennas include a first transmit antenna associated with a highest channel gain indicated by the received CSI, and a second transmit antenna associated with a highest channel gain indicated by the received CSI in a direction orthogonal to the first transmit antenna.

[0138] 11. A method according to any of clauses 1 to 3, clause 5 or clause 10, wherein the N transmit antennas further include a third transmit antenna having a highest channel gain indicated by the received CSI in a direction orthogonal to the first transmit antenna and the second transmit antenna.

[0139] 12. A method according to any of clauses 1 to 3, further comprising:

[0140] Antenna selection information indicating N transmitting antennas is received from a receiving device.

[0141] 13. A wireless communication device, comprising:

[0142] A number (N TX ) transmitting antennas;

[0143] at least one memory; and

[0144] At least one processor communicatively coupled to the at least one memory, the at least one processor configured to cause the wireless communication device to perform a method according to any one or more of clauses 1 to 12.

[0145] 14. A method for TX ) a wireless communication device having a transmitting antenna and performing a method for wireless communication, comprising:

[0146] Parse the physical layer (PHY) protocol data unit (PPDU) into a number (N SS ) spatial streams, where N SS ≥1;

[0147] N SS The spatial streams are modulated onto a number (M) of subcarriers spanning a bandwidth associated with a wireless channel;

[0148] Based on the number of spatial streams modulated onto the first subset of M subcarriers (N SS1 ) to map the first subset of M subcarriers to a number (K) of transmit antennas, where N SS1 ≤K <N TX ;

[0149] Based on the number of spatial streams modulated onto the second subset of M subcarriers (N SS2 ) to map the second subset of M subcarriers to a number (L) of transmit antennas, where N SS2 ≤L <N TX ;

[0150] transmitting a first portion of the PPDU to a receiving device via the K transmit antennas based on the mapping of the first subset of the M subcarriers; and

[0151] A second portion of the PPDU is transmitted to the receiving device via the L transmit antennas based on the mapping to the second subset of the M subcarriers.

[0152] 15. The method according to clause 16, wherein K = N SS1 And L = N SS2 .

[0153] 16. A method according to any of clauses 14 or 15, wherein the K transmit antennas are different from the L transmit antennas.

[0154] 17. A method according to any of clauses 14 to 17, wherein mapping of the first subset and the second subset of M subcarriers to the K transmit antennas and the L transmit antennas, respectively, is further based on a power spectral density (PSD) constraint associated with the wireless channel.

[0155] 18. A method according to any of clauses 14 to 18, wherein subcarriers belonging to a first subset of M subcarriers are unique to the first subset and subcarriers belonging to a second subset of M subcarriers are unique to the second subset.

[0156] 19. A method according to any of clauses 14 to 19, wherein the first subset of M subcarriers represents one or more first resource units (RUs) and the second subset of M subcarriers represents one or more second RUs.

[0157] 20. A method according to any of clauses 14 to 20, wherein the first subset of M subcarriers comprises a different number of subcarriers than the second subset of M subcarriers.

[0158] 21. A method according to any of clauses 14 to 21, wherein the mapping of the first subset or the second subset of the M subcarriers to the K transmit antennas or the L transmit antennas, respectively, is further based on indicating that the K transmit antennas are to be used for transmitting the N SS1 spatial streams and L transmit antennas are used to send N SS2 The lookup table for each spatial stream.

[0159] 22. A method according to any of clauses 14 to 21, wherein the mapping of the first subset or the second subset of the M subcarriers to the K transmit antennas or the L transmit antennas, respectively, is further based on a lookup table storing historical data associated with previous transmissions made by the wireless communication device.

[0160] 23. A method according to any of Clauses 14 to 21, further comprising:

[0161] Channel state information (CSI) is received from a receiving device, and mapping of the first subset or the second subset of M subcarriers to the K transmit antennas or the L transmit antennas, respectively, is further based on the received CSI.

[0162] 24. A method according to any of clauses 14-21 or 23, wherein the mapping of a first subset of M subcarriers to K transmit antennas is based on a lookup table and the mapping of a second subset of M subcarriers to L transmit antennas is based on received CSI.

[0163] 25. A method according to any of Clauses 14 to 21, further comprising:

[0164] Antenna selection information indicating K transmit antennas or L transmit antennas is received from a receiving device.

[0165] 26. A method according to any of Clauses 14 to 25, further comprising:

[0166] Based on the number of spatial streams modulated onto the third subset of M subcarriers (N SS3 ) to map the third subset of M subcarriers to a number (J) of transmit antennas, where N SS3 ≤J <N TX ;as well as

[0167] A third portion of the PPDU is transmitted to the receiving device via the J transmit antennas based on the mapping to the third subset of the M subcarriers.

[0168] 27. A wireless communication device, comprising:

[0169] A number (N TX ) transmitting antennas;

[0170] at least one memory; and

[0171] At least one processor communicatively coupled to the at least one memory, the at least one processor configured to cause the wireless communication device to perform a method according to any one or more of clauses 14-26.

[0172] As used herein, phrases referring to "at least one of" or "one or more of" a list of items refer to any combination of those items, including single members. For example, "at least one of a, b, or c" is intended to cover the possibilities of: 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. As used herein, "based on" is intended to be interpreted in an inclusive sense, unless expressly indicated otherwise. For example, "based on" may be used interchangeably with "based at least in part on," unless expressly indicated otherwise. Specifically, unless the phrase refers to "based only on 'a'" or an equivalent in context, either "based on 'a'" or "based at least in part on 'a'" may be based only on "a" or on a combination of "a" and one or more other factors, conditions, or information.

[0173] 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. The interchangeability of hardware, firmware, and software has been generally described around functionality and shown 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.

[0174] Various modifications to the implementations described in this disclosure may be apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other implementations without departing from the spirit or scope of the disclosure. Therefore, the claims are not intended to be limited to the implementations shown herein, but are to be given the widest scope consistent with the disclosure, the principles and novel features disclosed herein.

[0175] 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 individually or in any suitable subcombination. As such, while features may be described above as acting in a particular combination, and even initially claimed as such, in some cases, one or more features from a claimed combination may be removed from the combination, and a claimed combination may be directed to a subcombination or a variation of a subcombination.

[0176] Similarly, although the operation is described in a specific order in the accompanying drawings, this should not be understood as requiring such operation to be performed in the specific order shown or in the order of sequence, or requiring to perform all the operations shown to achieve the desired result. Further, the accompanying drawings can schematically describe one or more example processes in the form of a flow chart or a flow diagram. However, other operations not described can be incorporated into the example process schematically shown. For example, one or more additional operations can be performed before, after, at the same time or between any operation in the operation shown. In some cases, multitasking and parallel processing may be advantageous. In addition, the separation of each system component 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 system can usually be integrated together in a single software product, or encapsulated in multiple software products.

Claims

1. A method for forming a TX ) a wireless communication method performed by a wireless communication device having a transmitting antenna, comprising: Parse the physical layer (PHY) protocol data unit (PPDU) into a number (N SS ) spatial streams, where N SS ≥1; The N SS The spatial streams are modulated onto a number (M) of subcarriers spanning a bandwidth associated with a wireless channel; The M subcarriers are mapped to a number (N) of transmit antennas based on a power spectral density (PSD) constraint associated with the wireless channel, where N SS ≤N <N TX ;as well as The PPDU is transmitted to a receiving device via the N transmit antennas based on the mapping of the M subcarriers.

2. The method according to claim 1, wherein: N=N SS 。 3. The method according to claim 1, wherein: The mapping of the M subcarriers to the N transmit antennas is further based on indicating the N transmit antennas to be used for transmitting SS A lookup table for the N transmit antennas for each spatial stream.

4. The method according to claim 1, wherein: The mapping of the M subcarriers to the N transmit antennas is further based on a lookup table storing historical data associated with previous transmissions by the wireless communication device.

5. The method according to claim 1, further comprising: Channel state information (CSI) is received from the receiving device, and the M subcarriers are mapped to the N transmit antennas based on the received CSI.

6. The method according to claim 5, wherein: The N transmit antennas are associated with the N highest signal-to-noise ratios (SNRs) or the N highest signal-to-interference-plus-noise ratios (SINRs) indicated by the received CSI.

7. The method according to claim 5, wherein: The N transmit antennas are associated with the highest channel gains indicated by the received CSI.

8. The method according to claim 5, wherein: The N transmit antennas include a first transmit antenna associated with a highest channel gain indicated by the received CSI, and TX a second transmit antenna among the plurality of transmit antennas that has the lowest correlation with the first transmit antenna.

9. The method according to claim 8, wherein: The N transmitting antennas also include TX A third transmit antenna among the plurality of transmit antennas having the lowest correlation with the first transmit antenna and the second transmit antenna.

10. The method according to claim 5, wherein: The N transmit antennas include a first transmit antenna associated with a highest channel gain indicated by the received CSI, and a second transmit antenna associated with the highest channel gain indicated by the received CSI in a direction orthogonal to the first transmit antenna.

11. The method according to claim 10, wherein: The N transmit antennas also include a third transmit antenna having the highest channel gain indicated by the received CSI in a direction orthogonal to the first transmit antenna and the second transmit antenna.

12. The method according to claim 1, further comprising: Antenna selection information indicating the N transmitting antennas is received from the receiving device.

13. A wireless communication device, comprising: A number (N TX ) transmitting antennas; at least one memory; as well as at least one processor communicatively coupled to the at least one memory, the at least one processor configured to cause the wireless communication device to: Parse the physical layer (PHY) convergence protocol (PLCP) protocol data unit (PPDU) into a number (N SS ) spatial streams, where N SS ≥1; The N SS The spatial streams are modulated onto a number (M) of subcarriers spanning a bandwidth associated with a wireless channel; The M subcarriers are mapped to a number (N) of transmit antennas based on a power spectral density (PSD) constraint associated with the wireless channel, where N SS ≤N <N TX ;as well as The PPDU is transmitted to a receiving device via the N transmit antennas based on the mapping of the M subcarriers.

14. The wireless communication device according to claim 13, wherein: The mapping of the M subcarriers to the N transmit antennas is further based on a lookup table.

15. The wireless communication device according to claim 13, wherein: The at least one processor is further configured to cause the wireless communication device to: Channel state information (CSI) is received from the receiving device, and the M subcarriers are mapped to the N transmit antennas based on the received CSI.

16. A method for forming a TX ) a wireless communication method performed by a wireless communication device having a transmitting antenna, comprising: Parse the physical layer (PHY) protocol data unit (PPDU) into a number (N SS ) spatial streams, where N SS ≥1; The N SS The spatial streams are modulated onto a number (M) of subcarriers spanning a bandwidth associated with a wireless channel; Based on the number of spatial streams modulated onto the first subset of the M subcarriers (N SS1 ) to map the first subset of the M subcarriers to a number (K) of transmit antennas, where N SS1 ≤K <N TX ; Based on the number of spatial streams modulated onto the second subset of the M subcarriers (N SS2 ) to map the second subset of the M subcarriers to a number (L) of transmit antennas, where N SS2 ≤L <N TX ; transmitting a first portion of the PPDU to a receiving device via the K transmit antennas based on the mapping of the first subset of the M subcarriers; as well as A second portion of the PPDU is transmitted to the receiving device via the L transmit antennas based on the mapping of the second subset of the M subcarriers.

17. The method according to claim 16, wherein: K=N SS1 And L = N SS2 .

18. The method according to claim 16, wherein: The K transmit antennas are different from the L transmit antennas.

19. The method according to claim 16, wherein: Mapping of the first subset and the second subset of the M subcarriers to the K transmit antennas and the L transmit antennas, respectively, is further based on a power spectral density (PSD) limit associated with the wireless channel.

20. The method according to claim 16, wherein: The subcarriers belonging to the first subset of the M subcarriers are unique to the first subset, and the subcarriers belonging to the second subset of the M subcarriers are unique to the second subset.

21. The method according to claim 16, wherein: The first subset of the M subcarriers represents one or more first resource units (RUs), and the second subset of the M subcarriers represents one or more second RUs.

22. The method according to claim 16, wherein: The first subset of the M subcarriers includes a different number of subcarriers than the second subset of the M subcarriers.

23. The method according to claim 16, wherein: The mapping of the first subset or the second subset of the M subcarriers to the K transmit antennas or the L transmit antennas, respectively, is further based on indicating that the K transmit antennas are to be used for transmitting N SS1 spatial streams and the L transmit antennas are used to transmit N SS2 The lookup table for each spatial stream.

24. The method according to claim 16, wherein: Mapping of the first subset or the second subset of the M subcarriers to the K transmit antennas or the L transmit antennas, respectively, is further based on a lookup table storing historical data associated with previous transmissions by the wireless communication device.

25. The method of claim 16, further comprising: Channel state information (CSI) is received from the receiving device, and mapping the first subset or the second subset of the M subcarriers to the K transmit antennas or the L transmit antennas, respectively, is further based on the received CSI.

26. The method according to claim 25, wherein: The mapping of the first subset of the M subcarriers to the K transmit antennas is based on a lookup table, and the mapping of the second subset of the M subcarriers to the L transmit antennas is based on received CSI.

27. The method of claim 16, further comprising: Antenna selection information indicating the K transmit antennas or the L transmit antennas is received from the receiving device.

28. The method of claim 16, further comprising: Based on the number of spatial streams modulated onto the third subset of the M subcarriers (N SS3 ) to map the third subset of the M subcarriers to a number (J) of transmit antennas, where N SS3 ≤J <N TX ;as well as A third portion of the PPDU is transmitted to a receiving device via the J transmit antennas based on the mapping to the third subset of the M subcarriers.

29. A wireless communication device, comprising: A number (N TX ) transmitting antennas; at least one memory; as well as at least one processor communicatively coupled to the at least one memory, the at least one processor configured to cause the wireless communication device to: Parse the physical layer (PHY) convergence protocol (PLCP) protocol data unit (PPDU) into a number (N SS ) spatial streams, where N SS ≥1; The N SS The spatial streams are modulated onto a number (M) of subcarriers spanning a bandwidth associated with a wireless channel; Based on the number of spatial streams modulated onto the first subset of the M subcarriers (N SS1 ) to map the first subset of the M subcarriers to a number (K) of transmit antennas, where N SS1 ≤K <N TX ; Based on the number of spatial streams modulated onto the second subset of the M subcarriers (N SS2 ) to map the second subset of the M subcarriers to a number (L) of transmit antennas, where N SS2 ≤L <N TX ; transmitting a first portion of the PPDU to a receiving device via the K transmit antennas based on the mapping of the first subset of the M subcarriers; as well as A second portion of the PPDU is transmitted to the receiving device via the L transmit antennas based on the mapping of the second subset of the M subcarriers.

30. The wireless communication device of claim 29, wherein: The first subset of the M subcarriers does not overlap with the second subset of the M subcarriers.

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