BR112018011953B1 - POWER CONTROL FOR UPLINK TRANSMISSIONS - Google Patents

Abstract

POWER CONTROL FOR UPLINK TRANSMISSIONS. A method, an apparatus, and a computer-readable medium for wireless communication are provided. In one aspect, the apparatus is configured to determine a target receiver power level for uplink transmission. The device is configured to transmit to a wireless device. The frame may include information associated with the target receiver power level for uplink transmission and a transmit power level at which the frame is to be transmitted.

Description

CROSS REFERENCE TO RELATED ORDERS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 62/269,039, titled "POWER CONTROL FOR UP-LINK TRANSMISSIONS" and filed on December 17, 2015, and U.S. Patent Application No. Series 15/379,350, entitled "POWER CONTROL FOR UPLINK TRANSMISSIONS" and filed on December 14, 2016, which are expressly incorporated by reference herein in their entirety.

BASIS Field

[0002] The present disclosure relates generally to communication systems and particularly to power control for uplink transmissions.

Foundation

[0003] In many telecommunications systems, communication networks are used to exchange messages between multiple spatially separated interactive devices. Networks can be classified according to geographic scope, which can be, for example, a metropolitan area, a local area, or a personal area. Such networks would be designated, respectively, as a wide area network (WAN), metropolitan area network (MAN), local area network (LAN), wireless local area network (WLAN), or personal area network (PAN). . Networks also differ according to the switching/routing technique used to interconnect the various network nodes and devices (e.g., circuit switching vs. packet switching), the type of physical media used for transmission (e.g., with wired versus wireless) and the set of communication protocols used (e.g. Internet protocol suite, synchronous optical network (SONET), Ethernet, etc.).

[0004] Generally, wireless networks are preferred when the network elements are mobile and therefore have dynamic connectivity needs or if the network architecture is formed in an ad hoc, rather than fixed, topology. Wireless networks employ intangible physical media in an unguided propagation mode using electromagnetic waves in the radio, microwave, infrared, optical, etc. frequency bands. Wireless networks advantageously facilitate user mobility and rapid field deployment when compared to fixed wired networks.

SUMMARY

[0005] The systems, methods, computer-readable media, and devices of the invention each have various aspects, none of which are solely responsible for the desirable attributes of the invention. Without limiting the scope of this invention as expressed by the following claims, some features will now be briefly discussed. After considering this discussion, and particularly after reading the section titled "Detailed Description", we will understand how the features of this invention provide advantages to devices on a wireless network.

[0006] One aspect of this disclosure provides an apparatus (e.g., an access point) for wireless communication. The apparatus is configured to determine a power control command for a station that enables uplink (UL) multiple user (MU) multiple input multiple output (MIMO) transmission (MU-MIMO UL) or multiple access transmission orthogonal frequency division UL (OFDMA UL). The power control command may be associated with a station identifier that identifies the station for which the power control command is intended. The apparatus is configured to transmit a frame to a station identified by the station identifier. The frame may include the power control command given for MU-MIMO UL or OFDMA UL and the station identifier, and the power control command given for the station may be different from other power control commands for other associated stations. to the access point.

[0007] Another aspect of this disclosure provides an apparatus (e.g., a station) for wireless communication. The apparatus is configured to receive a first frame from an access point that includes a power control command to be used by the station for MU-MIMO UL transmission or OFDMA UL transmission. The station power control command may be different from other power control commands for other stations associated with the access point. The apparatus may be configured to determine a transmit power to transmit a second frame to the access point based on the power control command and to transmit the second frame based on the determined transmit power.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 shows an example of a wireless communication system in which aspects of the present disclosure may be employed.

[0009] FIG. 2 illustrates a power control command signaling method using an Rx power level option.

[0010] FIG. 3 illustrates an exemplary trigger frame that may correspond to the downlink frame in FIG. two

[0011] FIG. 4 shows an example of a functional block diagram of a wireless device that can be used in the wireless communication system of FIG. 1.

[0012] FIG. 5 is a flowchart of an example wireless communication method for controlling power by an access point.

[0013] FIG. 6 is a functional block diagram of an example wireless communication device configured to control uplink MU transmissions.

[0014] FIG. 7 shows an example of a functional block diagram of a wireless device that can be used in the wireless communication system of FIG. 1

[0015] FIG. 8 is a flowchart of an example wireless communication method for controlling power by a station.

[0016] FIG. 9 is a functional block diagram of an example wireless communication device configured for power control.

DETAILED DESCRIPTION

[0017] Various aspects of the new systems, apparatus, computer-readable media and methods are described in more detail below with reference to the accompanying drawings. This disclosure may, however, be incorporated in many different forms and should not be construed as limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure is exhaustive and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings presented herein, one of skill in the art should understand that the scope of the disclosure is intended to encompass any aspect of the novel systems, apparatus, computer program products and methods disclosed herein, whether implemented independently of, or combined with, any other aspect of the invention. . For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. Furthermore, the scope of the invention is intended to cover such apparatus or method that is practiced using another structure, functionality or structure and functionality in addition to or other than the various aspects of the invention set forth herein. It should be understood that any aspect disclosed herein may be embodied by one or more elements of a claim.

[0018] Although particular aspects are described herein, many variations and permutations of these aspects are within the scope of the disclosure. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the disclosure is not intended to be limited to specific benefits, uses or purposes. Rather, aspects of the disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks and transmission protocols, some of which are illustrated by way of example in the figures and the following description of preferred aspects. The detailed description and drawings are merely illustrative of the disclosure, rather than limiting, the scope of the disclosure being defined by the appended claims and their equivalents.

[0019] Popular wireless networking technologies can include various types of wireless local area networks (WLANs). A WLAN can be used to interconnect nearby devices by employing widely used network protocols. The various aspects described here can be applied to any communication standard, such as a wireless protocol.

[0020] In some aspects, wireless signals may be transmitted in accordance with an 802.11 protocol using OFDM (orthogonal frequency division multiplexing), (DSSS) direct sequence spread spectrum communications, a combination of OFDM and DSSS communications. or other schemes. Implementations of the 802.11 protocol can be used for sensors, measurements, and smart grid networks. Advantageously, aspects of certain devices that implement the 802.11 protocol may consume less power than devices that implement other wireless protocols and/or may be used to transmit wireless signals over a relatively long range, e.g., about one kilometer. or more.

[0021] In some implementations, a WLAN includes multiple devices, which are the components that access the wireless network. For example, there can be two types of devices: access points (APs) and clients (also called stations or "STAs"). In general, an AP can serve as a hub or base station for the WLAN and an STA serves as a user of the WLAN. For example, an STA can be a laptop computer, a personal digital assistant (PDA), a cell phone, etc. In one example, an STA connects to an AP over a Wi-Fi compatible wireless link (e.g., IEEE 802.11 protocol) to achieve general connectivity to the Internet or other wide area networks. In some implementations, an STA can also be used as an AP.

[0022] An access point may also comprise, be implemented as, or known as a NodeB, Radio Network Controller (RNC), eNodeB, Base Station Controller (BSC), Base Transceiver Station (BTS), Base Station (BS ), Transceiver Function (TF), Radio Router, Radio Transceiver, connection point or some other terminology.

[0023] A station may also comprise, be implemented as, or known as an access terminal (AT), a subscriber station, a subscriber unit, a mobile station, a remote station, a remote terminal, a user terminal , a user agent, a user device, a user equipment, or some other terminology. In some implementations, a station may comprise a cellular telephone, a cordless telephone, a Session Initiation Protocol (SIP) telephone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a portable computer with wireless connection capability, or some other suitable processing device connected to a wireless modem. Thus, one or more aspects taught here may be incorporated into a telephone (e.g., a cell phone or smartphone), a computer (e.g., a laptop), a portable communications device, a headset, a computing device portable (e.g., personal data assistant), an entertainment device (e.g., a music or video device or a satellite radio), a gaming device or system, a global positioning system device, or any other device appropriate that it is configured to communicate via a wireless medium.

[0024] The term "associate", or "association", or any variant thereof should be given the broadest possible meaning in the context of the present disclosure. By way of example, when a first device is associated with a second device, it must be understood that the two devices may be directly associated or that intermediate devices may be present. For brevity, the process for establishing an association between two devices will be described using a handshake protocol that requires a "association request" by one of the devices followed by a "association response" by the other device. It will be understood by those skilled in the art that the handshake protocol may require other signaling, such as, for example, signaling to provide authentication.

[0025] Any reference to an element here using a designation such as "first", "second" and so on generally does not limit the quantity or order of these elements. Rather, these designations are used here as a convenient method of distinguishing between two or more elements or instances of an element. Thus, a reference to the first and second elements does not mean that only two elements may be employed, or that the first element must precede the second element. Additionally, a phrase that refers to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: A, B, or C” is intended to cover: A , or B, or C, or any combination thereof (e.g., A-B, A-C, B-C, and A-B-C).

[0026] As discussed above, certain devices described herein can implement the 802.11 standard, for example. Such devices, whether used with the STA or AP or another device, can be used for smart metering or in a smart grid network. Such devices can provide sensor applications or be used in home automation. The devices may instead or, in addition, be used in a healthcare context, e.g. for personal healthcare. They can also be used for surveillance, to enable long-range Internet connectivity (e.g. for use with access points), or to implement machine-to-machine communications.

[0027] FIG. 1 shows an example of a wireless communication system 100 in which aspects of the present disclosure may be employed. The wireless communication system 100 may operate in accordance with a wireless standard, e.g., the 802.11 standard. The wireless communication system 100 may include an AP 104, which communicates with STAs (e.g., STAs 112, 114, 116, and 118).

[0028] A variety of processes and methods can be used for transmissions in the wireless communication system 100 between the AP 104 and the STAs. For example, signals may be sent and received between the AP 104 and the STAs in accordance with OFDM/OFDMA techniques. If this is the case, the wireless communication system 100 may be referred to as an OFDM/OFDMA system. Alternatively, signals may be sent and received between the AP 104 and the STAs in accordance with CDMA techniques. If this is the case, the wireless communication system 100 may be referred to as a CDMA system.

[0029] A communication link that facilitates transmission from the AP 104 to one or more of the STAs may be referred to as a downlink (DL) 108, and a communication link that facilitates transmission from one or more STAs to the AP 104 may be referred to as an uplink (UL) 110. Alternatively, a downlink 108 may be referred to as a forward link or a forward channel, and an uplink 110 may be referred to as a reverse link or a reverse channel. In some aspects, DL communications may include indications of unicast or multicast traffic.

[0030] The AP 104 can suppress adjacent channel interference (ACI) in some aspects, so that the AP 104 can receive UL communications on more than one channel simultaneously without causing significant analog-to-digital conversion (ADC) clipping noise . The AP 104 can improve ACI suppression, for example, by having separate finite impulse response (FIR) filters for each channel or by having a longer ADC backoff period with increased bit widths.

[0031] The AP 104 may act as a base station and provide wireless communications coverage in a basic service area (BSA) 102. A BSA (e.g., the BSA 102) is the coverage area of an AP (e.g., example, the AP 104). The AP 104, together with the STAs associated with the AP 104 and using the AP 104 for communication, may be referred to as a basic service set (BSS). It should be noted that the wireless communication system 100 may not have a central AP (e.g., AP 104), but may function as a peer-to-peer network between the STAs. Accordingly, the functions of the AP 104 described herein may alternatively be performed by one or more of the STAs.

[0032] The AP 104 may transmit on one or more channels (e.g., multiple narrowband channels, each channel including a frequency bandwidth) a beacon signal (or simply a "beacon"), via a link of communication, such as downlink 108, to other nodes (STAs) of the wireless communication system 100, which may help the other nodes (STAs) to synchronize their time with the AP 104, or which may provide other information or functionality. Such beacons may be transmitted periodically. In one aspect, the period between successive transmissions may be referred to as a superframe. The transmission of a beacon can be divided into several groups or slots. In one aspect, the flag may include, but is not limited to, information such as timestamp information to define a common clock, a peer-to-peer network identifier, a device identifier, capacity information, a duration of superframe, transmit direction information, receive direction information, a neighbor list and/or an extended neighbor list, some of which are described in additional detail below. Thus, a flag may include information that is common (e.g., shared) among multiple devices and specific to a given device.

[0033] In some aspects, a STA (e.g., STA 114) may be required to associate with AP 104 to send communications to and/or receive communications from AP 104. In one aspect, information for association is included in a transmission of beacons by the AP 104. To receive such a beacon, the STA 114 may, for example, perform a broad coverage survey over a coverage region. A search can also be performed by the STA 114 by scanning a coverage region of a beacon mode, for example. After receiving the association information, the STA 114 may transmit a reference signal, such as an association probe or request, to the AP 104. In some aspects, the AP 104 may use backhaul services. ), for example, to communicate with a larger network, such as the Internet or a public switched telephone network (PSTN).

[0034] In one aspect, the AP 104 may include one or more components to perform various functions. For example, the AP 104 may include an uplink control component 124 to perform procedures related to uplink power control. In this example, the uplink control component 124 may be configured to determine a target receiver power level for uplink transmission. The uplink control component 124 may be configured to transmit a frame to a wireless device. The frame may include information associated with the target receiver power level determined for uplink transmission and a transmit power level at which the frame is to be transmitted.

[0035] In another aspect, the STA 114 may include one or more components to perform various functions. For example, the STA 114 may include a power control component 126 to perform procedures related to uplink power control. In this example, the power control component 126 may be configured to receive a frame from an access point. The frame may include information indicating a target receiver power level determined at the access point or a transmit power level to be used by the STA 114 for uplink transmission. The power control component 126 may be configured to transmit a second frame to the access based on the information received.

[0036] In wireless networks, transmission power control is generally required for uplink multi-user transmissions. For example, in networks that support OFDMA (orthogonal frequency division multiple access) and/or MU-MIMO (multiple user multiple input), some form of transmit power control may be required. In OFDMA, power control can be used to manage interference between different resource units (RUs) by controlling the power imbalance between STAs scheduled in adjacent RUs. An RU can be, for example, a subset of tones within a symbol. An RU can have 26 tones, 52 tones, 106 tones, 242 tones, 484 tones, 996 tones, 2x996 tones, or some other number of tones. Transmit power control can also be used to meet power spectral density (PSD) requirements and mitigate leakage. In MU-MIMO, transmit power control can be used to manage inter-stream interference (e.g., multiple spatial streams) by controlling power imbalance between STAs scheduled for transmission and interference from overlapping BSSs (OBBSs). For example, in MU-MIMO, all STAs or a group of STAs can be scheduled or allocated in the same RU and therefore transmitted on the same frequency but in different spatial streams. In another example, as in OFDMA, STAs can be scheduled to transmit at the same time, but on different frequencies. Power control can also be used to ensure that UL transmissions do not exceed the dynamic receive range of the AP.

[0037] When multiple users are scheduled for uplink transmission at the same time, near-far effect may occur. Near-far effect is a condition in which a device receives a strong signal and cannot detect a weaker signal. To minimize the impact of the near-far effect on receiver performance, a power (e.g. transmit power) and rate (e.g. MCS rate) control scheme is required. ) that allows an access point, for example, to have the flexibility to control the power and transmission rate of each station in OFDMA and MU-MIMO transmissions.

[0038] FIG. 2 illustrates a power control command signaling method. Referring to FIG. 2, an AP can be serving multiple STAs within a BSS. The AP can schedule the STAs for MU UL transmission using open-loop control (e.g., power control with limited or no feedback from the STAs). In basic open loop control, all STAs scheduled for MU UL transmission can receive the same information for power control. For example, STAs can determine a target signal-to-noise ratio (SNR) at the AP based on an MCS-SNR table. The table may be indicated explicitly or implicitly by the AP (e.g., transmitted by the AP through an information element or during association). In this example, the AP may indicate an MCS, and the STA may look for the target SNR based on the indicated MCS and determine a Tx power based on the target SNR. However, selecting the target SNR based on a table may result in problems during MU UL transmissions. For example, the target SNR and the received SNR at the AP may be different. Hardware limitations may cause inaccurate STA Tx power levels as a result of received signal strength indicator (RSSI) measurement errors and Tx power calibration errors (for example, the STA may be transmitting at a higher Tx power or smaller than intended). Furthermore, the path loss of UL and DL may not be reciprocal (or the same). DL RSSI can run on 20 megahertz (MHz) channels, while UL path loss for smaller RUs can differ from DL path loss due to frequency selectivity. For example, if the entire uplink bandwidth is 40 MHz and is divided among 8 users, each user can have 5 MHz for uplink transmission. However, the path loss for a 20 MHz channel may be different to the path loss for a 5 MHz channel (or some other smaller channel, such as a 10 MHz channel). The more bandwidth there is in the average, the less frequency selectivity there is, which can reduce channel jitter (for example, there may be deep fading within the 5 MHz channel). As such, a target SNR alone may be insufficient for successful decoding of UL transmissions received at the AP. A power imbalance between scheduled STAs may be greater than tolerance levels, and required SNRs may vary based on the number of users in MU-MIMO UL (or OFDMA UL).

[0039] In another scenario, when multiple STAs are scheduled for MU UL transmissions, one of the STAs may have a high packet error rate (PER) across multiple MU UL transmissions. The SNR received for the STA at the AP may be lower than necessary for successful decoding. Currently, the AP may have limited options to handle this scenario. In one solution, the AP can adjust the power control command to increase the target SNR for all users and all MCS values. However, this solution may be inefficient for users who are not affected by high PER. Additionally, increasing the target SNR can reduce overall throughput because when more STAs transmit at higher power, there is greater interference. In another solution, the AP can download the MCS to the affected STA. However, if the target SNR is determined based on the MCS-SNR table, the problem may persist because the STA TX power is also reduced. Furthermore, a conservative scheduling approach (e.g., with a large SNR margin) may compromise MU UL throughput because the SNR margin may have to be quite high (e.g., greater than 6 dB) and increase transmit power. can increase interference and decrease overall throughput.

[0040] In other words, STAs need to transmit with sufficient power to ensure adequate SNR on the AP for the assigned MCS. Higher than necessary transmit power levels can cause unnecessary interference to other users, which is especially true for low MCS transmissions with free error vector magnitude (EVM) requirements. It is useful that an AP can adjust the power and transmission rate independently for each STA in a MU UL transmission. This allows the AP to adapt to different channel conditions for single-user and MU-MIMO transmissions. In one aspect, in a modified open-loop power control scheme, to compensate for different data reception scenarios, the AP can select individualized MCSs and individualized target SNR for each STA scheduled for MU UL transmission based on each hardware limitations. of the STA, as well as based on other STAs and the MCS scheduled in the MU UL transmission. For example, if 4 STAs are scheduled for MU UL transmission, the AP can provide different power control commands to each of the 4 STAs based on the hardware limitations of each STAs. In another aspect, the transmission rate and power control algorithm may be internal to the AP implementation and may be transparent to the STA. In this aspect, the AP does not need to advertise the MCS-SNR table, and the design and performance details of the AP receiver can be proprietary.

[0041] In one aspect, to implement individualized power control for MU UL transmission, an AP 202 may transmit a downlink frame 210 (e.g., a trigger frame or other type of downlink frame) to a STA 204. Downlink frame 210 may indicate a Tx power used by AP 202 to transmit downlink frame 210, an MCS to be used by a particular STA for uplink transmission, and/or a power control command to an uplink MU-MIMO (or OFDMA) transmission 220 to the particular STA. In one aspect, Tx power may be determined by the AP 202 based on an MCS and other factors, such as a number of users, an inter-stream management configuration of the AP 202, and grouping algorithms. For example, for an MCS value of 7 with 3 users, the AP 202 may select a Tx power level of -40 dBm. In another example, for an MCS value of 9 with 3 users, the AP 202 may select a Tx power level of -25 dBm. As such, the algorithm used to determine the specific Tx power level may depend on the AP settings. In addition to the Tx power, the downlink frame 210 may include one or more STA identifiers (IDs), such as an association identifier (AID), for which the downlink frame 210 is intended. Each power control command and/or MCS indicated in the downlink frame 210 may be associated with an STA ID to provide individualized power control. The downlink frame 210 may further include other parameters such as an RU size (e.g., 26-tone RU, 52-tone RU, 106-tone RU, etc.), a bandwidth, transmission duration, and a number of spatial streams allowed per STA and/or an amount of padding to be used at the end of the frame. Each of the parameters may be different or the same between the different STAs served by the AP 202.

[0042] The AP 202 power control command, as shown in FIG. 2, may indicate a target SNR for each STA. The AP 202 may have several options for indicating the target SNR in the power control command. In a first option, the power control command may indicate, for example, a target RSSI for each STA scheduled in the downlink frame 210 based on a STA ID associated with each STA. In this option, the STA 204 may compute a downlink path loss based on the received downlink frame 210. For example, the STA 204 may measure the RSSI of the received downlink frame 210, and based on the measured RSSI and the indicated Tx power level of the downlink frame 210 (TxAPpwr (dBm)), the STA 204 can determine the downlink path loss (e.g., downlink path loss = Tx power - measured RSSI). In one aspect, the indicated Tx power level may combine the power of all transmit antennas on the AP 202, although the STA may not know the number of antennas on the AP 202. The Tx power level may be the average power on a 20 MHz unit (e.g., resource unit), because in some cases, the STA 204 may not know the bandwidth of the downlink frame 210 (or trigger frame) when the downlink frame 210 is transmitted from according to previous standards. In another aspect, the Tx power level may have a resolution of 1 dB and be within a range [-20 40] dBm. The Tx power level can be represented using 6 bits, in which values 0 to 60 are mapped to -20 dBm to 40 dBm and values 61, 62 and 63 can be reserved. In another aspect, the target RSSI may correspond to the average RSSI over the antennas of the AP 202 and may have a resolution of 1 dB. The target RSSI can be represented using 7 bits, with values from 0 to 90 mapped to the range [-110, -20] dBm at 1 dB resolution. A value of 127 may correspond to a request for the STA 204 to use its maximum allowable transmit power for the assigned MCS. The lower end of the range may be useful for power control in narrowband transmissions such as 26-tone RUs, and the higher end of the range may be useful for power control when the AP 202 and STAs are in close proximity.

[0043] The STA 204 may determine the Tx power used for UL transmission based on the computed downlink path loss, the power control command, and/or a target SNR (e.g., TxAPpwr (dBm) = PLDL (dB) + TargetRSSI (dBm)). The STA 204 may determine a TX power by adding the target RSSI to the computed downlink path loss and using the sum as the Tx power for uplink transmission. In a second option, the AP 202 may indicate an SNR correction, which may be signaled as a value, and the value may be a delta to be applied to the SNR indicated in an MCS-SNR table. In one aspect, the target SNR may be indicated in the downlink frame 210. In another aspect, the downlink frame 210 may indicate an MCS in addition to the SNR correction. The STA 204 may determine an SNR associated with the MCS (e.g., based on an MCS-SNR table). The STA 204 may adjust the SNR indicated in the MCS-SNR table using the SNR correction in the downlink frame 210. Based on the adjusted target SNR, the STA 204 may determine a Tx power level and transmit OFDMA or MU-MIMO transmissions of uplink to the AP 202 based on the determined Tx power level. In a third option, the power control command can be indicated with a link margin (LM), which can be a combination of Tx AP power and receiver sensitivity. The LM can be defined based on Eq. 1: LMindex = Ptx_AP + Rsensitivity_AP

[0044] Referring to Eq. 1, LM is defined as the sum of the Tx AP power (Ptx AP) and the target RSSI (Rsensitivity AP). Upon receiving the LM in downlink frame 210, the STA 204 may subtract from the LM the measured downlink RSSI based on the received downlink frame 210, and the difference may be the Tx power to be used by the STA 204 for transmission. uplink. In this third option, the STA 204 may not need to compute downlink path loss to determine Tx power for MU UL transmission.

[0045] To enable the AP 202 to determine an appropriate power control command, the STA 204 may signal to the AP 202 certain Tx power limitations associated with the STA 204. In one aspect, the STA 204 may signal a Tx power current STA (PTxSTA). In another aspect, the STA 204 can signal a free space value, which can be determined based on free space = PMAXMCS - PTxMCS, where PMAXMCS is the maximum transmit power for an MCS and PTxMCS is the current transmit power for an MCS. the MCS. The free space may indicate an increase in the amount of transmit power available to the MCS by the STA 204, and the AP 202 may not request that the STA 204 increase its power beyond the value indicated in the free space value. The free space value can be signaled in the broadcast of the triggered MU UL to aid in the selection of AP MCs. The free space value can be signaled with 6 bits, of which 5 bits can be used to indicate a value from 0 to 31, corresponding to a range of [0, 31] dB. A remaining bit may be a flag used to indicate whether the minimum transmit power of a current MCS is reached by the STA 204. For example, if the flag is set to 1, then the STA 204 is already transmitting at its minimum transmit power. capable for the current MCS and the AP 202 may not require the STA 204 to further reduce its transmit power. If the flag is set to 0, then the STA 204 is not transmitting at its minimum transmit power for the current MCS. In another aspect, the STA 204 can signal an increase in relation to the floor value based on the increase over floor = PTxMCS - Pmin, where Pmin corresponds to the minimum transmission power of the STA 204 and the value of the increase over floor represents the margin in which current transmit power of an MCS exceeds the minimum transmit power of the STA 204. Increasing the floor value may allow the AP 202 to determine how much lower the Tx power of an STA can be reduced, for example. The STA 204 may signal a power amplifier backoff value for each MCS. Other power limitations may also be signaled from the STA 204 to the AP 202.

[0046] FIG. 3 illustrates an exemplary trigger frame 300 that may correspond to the downlink frame in FIG. 2 Trigger frame 300 may request and allocate resources for MU UL transmission in an interframe space (IFS) after trigger frame 300. The trigger frame may include a frame control field 302, a duration field 304 , a receiver address (RA) field 306, a transmit address (TA) field 308, a common information field 310, one or more user information fields 312, a padding 314, and a check sequence frame 316. The RA field 306 may identify the address of the receiving STA. If trigger frame 300 has a recipient STA, then RA field 306 is the MAC address of the STA. If the trigger frame 300 has multiple recipient STAs, then the RA field 306 may include a broadcast address. The TA field 308 may include the address of the device transmitting the trigger frame (e.g., the AP 202). Common information field 310 may include a number of subfields, including an AP TX power subfield that includes the transmit power level used by the AP to transmit trigger frame 300. The transmit power level may represent the average power combined by 20 MHz of bandwidth of all transmit antennas used to transmit trigger frame 300.

[0047] Referring to FIG. 3, a user information field may include an association ID (AID) subfield 318, an RU allocation subfield 320, an encoding type subfield 322, an MCS subfield 324, a carrier modulation subfield 326 (DCM), a spatial stream allocation subfield 328, a target RSSI subfield 330, a reserved subfield 332, and/or a trigger-dependent user information subfield 334. AID subfield 318 may identify the user to the which user information field is intended. RU allocation subfield 320 may indicate the resource unit used by an STA identified in AID subfield 318. Encoding type subfield 322 indicates the type of code (e.g., binary convolution encoding or low-density parity check encoding). MCS subfield 324 may indicate the MCS assigned to the STA identified in AID subfield 318. Subfield 326 DCM indicates dual carrier modulation. Spatial stream allocation subfield 328 indicates the number of spatial streams to be used by the STA. Subfield 330 of the target RSSI indicates the strength of the target received signal. Reserved subfield 332 allows for additional STA-addressed fields, and trigger-dependent user information subfield 334 may include additional per-user information. Padding subfield 314 lengthens the frame length to give the receiving STA more time to prepare a response. FCS subfield 316 allows error detection of trigger frame 300.

[0048] FIG. 4 shows an example functional block diagram of a wireless device 402 that can be used in the wireless communication system 100 of FIG. 1 to provide MU uplink power control. Wireless device 402 is an example of a device that can be configured to implement the various methods described herein. For example, wireless device 402 may comprise AP 104 or AP 202.

[0049] The wireless device 402 may include a processor 404 that controls the operation of the wireless device 402. The processor 404 may also be referred to as a central processing unit (CPU). Memory 406, which may include read-only memory (ROM) and random access memory (RAM), may provide instructions and data to processor 404. A portion of memory 406 may also include non-volatile random access memory (NVRAM). Processor 404 typically performs logical and arithmetic operations based on program instructions stored in memory 406. Instructions in memory 406 may be executable (by processor 404, for example) to implement the methods described herein.

[0050] Processor 404 may comprise or be a component of a processing system implemented with one or more processors. One or more processors can be implemented with any combination of general-purpose microprocessors, microcontrollers, digital signal processors (DSPs), FPGAs (Field Programmable Gate Array), programmable logic devices (PLDs), controllers, state machines, gated logic, discrete hardware components, dedicated hardware finite state machines, or any other suitable entities that can perform calculations or other information manipulation.

[0051] The processing system may also include machine-readable media for storing software. Software should be interpreted broadly to mean any type of instructions, whether called software, firmware, middleware, microcode, hardware description language, or otherwise. Instructions may include code (e.g., in source code format, binary code format, executable code format, or any other suitable code format). Instructions, when executed by one or more processors, cause the processing system to perform the various functions described here.

[0052] The wireless device 402 may also include an enclosure 408, and the wireless device 402 may include a transmitter 410 and/or a receiver 412 to enable the transmission and reception of data between the wireless device 402 and a remote device . Transmitter 410 and receiver 412 may be combined into a transceiver 414. An antenna 416 may be attached to housing 408 and electrically coupled to transceiver 414. Wireless device 402 may also include multiple transmitters, multiple receivers, multiple transceivers, and/or multiple antennas.

[0053] The wireless device 402 may also include a signal detector 418 that may be used to detect and quantify the level of signals received by the transceiver 414 or the receiver 412. The signal detector 418 may detect such signals as full power, power per subcarrier per symbol, power spectral density and other signals. The wireless device 402 may also include a DSP 420 for use in signal processing. The DSP 420 can be configured to generate a packet for transmission. In some aspects, the packet may comprise a physical layer convergence protocol (PLCP) protocol data unit (PPDU).

[0054] The wireless device 402 may further comprise a user interface 422 in some aspects. The user interface 422 may comprise a keyboard, a microphone, a speaker, and/or a monitor. The user interface 422 may include any element or component that transmits information to a user of the wireless device 402 and/or receives input from the user.

[0055] When the wireless device 402 is implemented as an AP (e.g., AP 104), the wireless device 402 may also comprise an uplink control component 424. The uplink control component 424 may be configured to determine 460 a power control command 450 to a station that allows MU-MIMO UL transmission or OFDMA UL transmission. The power control command may be associated with a station identifier that identifies the station for which the power control command is intended. The uplink control component 424 may be configured to transmit a frame to the station identified by the station identifier. The frame may include the power control command determined for MU-MIMO UL or OFDMA UL and the station identifier. The power control command determined for the station is different (or separate) from other power control commands for other stations associated with the access point. In one aspect, the power control command indicates at least one of a target RSSI expected at the access point, an SNR correction to be applied at the station, or a link margin. In another aspect, the frame may be a trigger frame 440, and the trigger frame may include the target RSSI and a transmit power level used to transmit the trigger frame. In another aspect, the target RSSI may indicate an average RSSI over a set of antennas associated with the access point. In another aspect, the trigger frame may be intended for a plurality of stations, and the trigger frame may include a separate power control command for each station of the plurality of stations. In another configuration, the uplink control component 424 may be configured to receive power information 430 associated with the station. The power information may include a free space value and the power control command may be determined based on the free space value. In another aspect, the power information may further include a flag indicating whether the station is transmitting at a minimum transmit power associated with an MCS index. In another aspect, the power control command may be directed to a single station performing MU-MIMO UL or OFDMA UL transmissions in a wireless local area network.

[0056] The various components of the wireless device 402 may be coupled together by a bus system 426. The bus system 426 may include a data bus, for example, as well as a power bus, a signal bus, control and a status signal bus in addition to the data bus. The components of the wireless device 402 may be coupled together or accept or provide input to each other using some other mechanism.

[0057] Although a number of separate components are illustrated in FIG. 4, one or more of the components can be combined or commonly implemented. For example, the processor 404 may be used to implement not only the functionality described above with respect to the processor 404, but also to implement the functionality described above with respect to the signal detector 418, the DSP 420, the user interface 422, and /or the uplink control component 424. Additionally, each of the components illustrated in FIG. 4 can be implemented using a plurality of separate elements.

[0058] FIG. 5 is a flowchart of an example method 500 of wireless communication for controlling power by an access point. The method 500 may be performed using an apparatus (e.g., the AP 104 or the wireless device 402, for example). Although method 500 is described below with respect to elements of the wireless device 402 of FIG. 4, other components may be used to implement one or more of the steps described herein. The dotted lines in relation to the various blocks represent optional blocks.

[0059] In block 505, the apparatus may receive power information associated with a station. The power information may include a free space value, floor lift information, a current transmit power of the station associated with an assigned MCS, a maximum transmit power associated with the MCS, a minimum transmit power of the station, and/or or backoff values associated with each MCS for the station. For example, referring to FIG. 2, the AP 202 can receive power information associated with the STA 204.

[0060] In block 510, the apparatus may determine a power control command for uplink transmission. The power control command may be associated with a station identifier. For example, referring to FIG. 2, the AP 202 may determine the power control command to the STA 204 for uplink transmission. The power control command may be associated with a STA ID that identifies the STA 204. The AP 202 may determine the power control command based on the power control capabilities received from the STA 204 and/or the number of users that request uplink transmission. For example, the AP 202 may determine the free space on the STA 204 and the minimum transmit power of the STA 204. Based on the free space or the minimum transmit power of the STA 204, the AP 202 may determine a target RSSI on the AP 202.

[0061] In block 515, the apparatus may transmit a frame to a station identified by the station identifier. The frame includes the power control command determined for uplink transmission by the station. For example, referring to FIG. 2, the AP 202 may transmit a trigger frame to the STA 204, and the trigger frame may include an STA ID that identifies the STA. The trigger frame may include the given power control command used for uplink transmission by the STA 204. For example, the STA 204 may indicate the target RSSI. Subsequently, the STA 204 may transmit data to the AP 202. Based on the received data, the AP 202 may adjust the target RSSI to be transmitted to the STA 204 for subsequent transmissions.

[0062] FIG. 6 is a functional block diagram of an example wireless communications device 600 configured to control uplink MU transmissions. The wireless communication device 600 may include a receiver 605, a processing system 610, and a transmitter 615. The processing system 610 may include an uplink control component 624. The processing system 610 and/or the uplink control 624 may be configured to determine 660 a power control command 650 for a station that enables MU-MIMO UL transmission or OFDMA UL transmission. The power control command may be associated with a station identifier that identifies the station for which the power control command is intended. The processing system 610, the uplink control component 624, and/or the transmitter 615 may be configured to transmit a frame to the station identified by the station identifier. The frame may include the power control command determined for MU-MIMO UL or OFDMA UL and the station identifier. The power control command determined for the station may be different (or separate) from other power control commands for other stations associated with the wireless communication device 600. In one aspect, the power control command may indicate at least one of an expected target RSSI at the wireless communication device 600, an SNR correction to be applied at the station, or a link margin. In another aspect, the frame may be a trigger frame 640, and the trigger frame may include the target RSSI and a transmit power level used by the wireless communication device 600 to transmit the trigger frame. In another aspect, the target RSSI may indicate an average RSSI across a set of antennas associated with the wireless communication device 600. In another aspect, the trigger frame may be intended for a plurality of stations, and the trigger frame may include a separate power control command for each station of the plurality of stations. In another configuration, the processing system 610, the receiver 605 and/or the uplink control component 624 may be configured to receive power information 630 associated with the station. The power information may include a free space value and the power control command may be determined based on the free space value. In another aspect, the power information may further include a flag indicating whether the station is transmitting at a minimum transmit power associated with an MCS index. In another aspect, the power control command may be directed to a single station performing MU-MIMO UL or OFDMA UL transmissions in a wireless local area network.

[0063] The receiver 605, the processing system 610, the uplink control component 624, and/or the transmitter 615 may be configured to perform one or more functions discussed above in connection with blocks 505, 510, and 515 of FIG. 5 Receiver 605 may correspond to receiver 412. Processing system 610 may correspond to processor 404. Transmitter 615 may correspond to transmitter 410. Uplink control component 624 may correspond to uplink control component 124 and/or or to the uplink control component 424.

[0064] In one configuration, the wireless communication device 600 includes means for determining a power control command for a station that enables MU-MIMO UL transmission or OFDMA UL transmission. The power control command may be associated with a station identifier that identifies the station for which the power control command is intended. The wireless communication device 600 may include means for transmitting a frame to the station identified by the station identifier. The frame may include the power control command determined for MU-MIMO UL or OFDMA UL and the station identifier. The power control command determined for the station may be different (or separate) from other power control commands for other stations associated with the wireless communication device 600. In one aspect, the power control command may indicate at least one of an expected target RSSI at the wireless communication device 600, an SNR correction to be applied at the station, or a link margin. In another aspect, the frame may be a trigger frame, and the trigger frame may include the target RSSI and a transmit power level used by the wireless communication device 600 to transmit the trigger frame. In another aspect, the target RSSI may indicate an average RSSI across a set of antennas associated with the wireless communication device 600. In another aspect, the trigger frame may be intended for a plurality of stations, and the trigger frame may include a separate power control command for each station of the plurality of stations. In another embodiment, the wireless communication device 600 may include means for receiving power information associated with the station. The power information may include a free space value and the power control command may be determined based on the free space value. In another aspect, the power information may further include a flag indicating whether the station is transmitting at a minimum transmit power associated with an MCS index. In another aspect, the power control command may be directed to a single station performing MU-MIMO UL or OFDMA UL transmissions in a wireless local area network.

[0065] For example, the means for determining a power control command may include the processing system 610 and/or the uplink control component 624. Means for transmitting a frame may include the processing system 610 and/or the transmitter 615. Means for receiving power information may include the processing system 610 and/or the receiver 605.

[0066] FIG. 7 shows an example functional block diagram of a wireless device 702 with uplink power control that can be used in the wireless communication system 100 of FIG. 1. Wireless device 702 is an example of a device that can be configured to implement the various methods described herein. For example, the wireless device 702 may comprise the STA 114 or the STA 204.

[0067] The wireless device 702 may include a processor 704 that controls the operation of the wireless device 702. The processor 704 may also be referred to as a CPU. Memory 706, which may include ROM and RAM, may provide instructions and data to processor 704. A portion of memory 706 may also include NVRAM. Processor 704 typically performs logical and arithmetic operations based on program instructions stored in memory 706. Instructions in memory 706 may be executable (by processor 704, for example) to implement the methods described herein.

[0068] Processor 704 may comprise or be a component of a processing system implemented with one or more processors. One or more processors may be implemented with any combination of general-purpose microprocessors, microcontrollers, DSPs, FPGAs, PLDs, controllers, state machines, gated logic, discrete hardware components, dedicated hardware finite state machines, or any other suitable entities that can perform calculations or other manipulations of information.

[0069] The processing system may also include machine-readable media for storing software. Software should be interpreted broadly to mean any type of instructions, whether called software, firmware, middleware, microcode, hardware description language, or otherwise. Instructions may include code (e.g., in source code format, binary code format, executable code format, or any other suitable code format). Instructions, when executed by one or more processors, cause the processing system to perform the various functions described here.

[0070] The wireless device 702 may also include an enclosure 708, and the wireless device 702 may include a transmitter 710 and/or a receiver 712 to enable the transmission and reception of data between the wireless device 702 and a remote device . Transmitter 710 and receiver 712 may be combined into a transceiver 714. An antenna 716 may be attached to housing 708 and electrically coupled to transceiver 714. Wireless device 702 may also include multiple transmitters, multiple receivers, multiple transceivers, and/or multiple antennas.

[0071] The wireless device 702 may also include a signal detector 718 that may be used to detect and quantify the level of signals received by the transceiver 714 or the receiver 712. The signal detector 718 may detect such signals as full power, power per subcarrier per symbol, power spectral density and other signals. The wireless device 702 may also include a DSP 720 for use in signal processing. The DSP 720 can be configured to generate a packet for transmission. In some aspects, the package may comprise a PPDU.

[0072] The wireless device 702 may further comprise a user interface 722 in some aspects. The user interface 722 may comprise a keyboard, a microphone, a speaker, and/or a monitor. The user interface 722 may include any element or component that transmits information to a user of the wireless device 702 and/or receives input from the user.

[0073] When the wireless device 702 is implemented as a station (e.g., the STA 114 or the STA 204), the wireless device 702 may also comprise a power control component 724. The power control component 724 may be configured to receive a first frame from an access point that includes a power control command to be used by the wireless device 702 for MU-MIMO UL transmission or OFDMA UL transmission. The power control command for the wireless device 702 may be different (or separate) from other power control commands for other stations associated with the access point. The power control component 724 may be configured to determine a transmit power to transmit a second frame to the access point based on the received power control command. The power control component 724 may be configured to transmit the second frame based on the determined transmit power. In one aspect, the power control command may indicate at least one of a target RSSI expected at the access point, an SNR correction to be applied at the wireless device 702, or a link margin. In another aspect, the first frame may be a trigger frame. The trigger frame may include the target RSSI at the access point and a second transmit power used by the access point to transmit the trigger frame. In another configuration, the power control component 724 may be configured to determine transmit power by computing a downlink path loss between the access point and the wireless device 702 and adding the link path loss measurement. descending to the target RSSI. In this configuration, the transmit power can be a sum of the downlink path loss measurement and the target RSSI. In one configuration, the power control component 724 may be configured to compute downlink path loss by measuring an RSSI of the trigger frame and subtracting the measured RSSI from the second transmit power used by the access point to transmit the trigger frame. shooting. In this configuration, the downlink path loss can be a difference between the second transmit power and the measured RSSI. In another embodiment, the power control component 724 may be configured to transmit power information to the access point. The power information may include at least one free space information, floor boost information, a current transmit power associated with an MCS, a maximum transmit power associated with the MCS, a minimum transmit power of the station, or values of backoff associated with each MCS. In this configuration, the power control command in the first message may be based on the transmitted power information.

[0074] The various components of the wireless device 702 may be coupled together by a bus system 726. The bus system 726 may include a data bus, for example, as well as a power bus, a control signal bus, and a control signal bus. and a status signal bus in addition to the data bus. The components of the wireless device 702 may be coupled together or accept or provide input to each other using some other mechanism.

[0075] Although a number of separate components are illustrated in FIG. 7, one or more of the components can be combined or commonly implemented. For example, the processor 704 may be used to implement not only the functionality described above with respect to the processor 704, but also to implement the functionality described above with respect to the signal detector 718, the DSP 720, the user interface 722, and /or the power control component 724. Furthermore, each of the components illustrated in FIG. 7 can be implemented using a plurality of separate elements.

[0076] FIG. 8 is a flowchart of an example wireless communication method 800 for controlling power by a station. The method 800 can be performed using an apparatus (e.g., the STA 114 or the wireless device 702, for example). Although method 800 is described below with respect to elements of the wireless device 702 of FIG. 7, other components may be used to implement one or more steps described herein. The dotted lines in relation to the various blocks represent optional blocks.

[0077] In block 805, the apparatus can transmit power information to an access point. The power information may include at least one free space information, floor boost information, a current transmit power associated with an MCS, a maximum transmit power associated with the MCS, a station minimum transmit power, and/or values backoff associated with each MCS supported by the device. For example, referring to FIG. 2, the STA 204 may transmit power information that includes free space information, a current transmit power associated with an MCS, and a floor boost information associated with the STA.

[0078] In block 810, the apparatus may receive a first frame from the access point that may include a power control command to be used by the apparatus for uplink transmission. For example, referring to FIG. 2, the STA 204 may receive a trigger frame from the AP 202 that includes a target RSSI to be used by the STA 204 for uplink transmission.

[0079] In block 815, the apparatus may determine a transmission power to transmit a second frame to the access point based on the power control command. For example, referring to FIG. 2, the STA 204 may determine a Tx power to transmit a frame to the AP 202 based on the target RSSI. The Tx power can be determined as the sum of the target RSSI and the downlink path loss measured from the received trigger frame.

[0080] In block 820, the apparatus may transmit the second frame based on the determined transmission power. For example, referring to FIG. 2, the STA 204 may transmit the uplink frame based on the determined Tx power.

[0081] FIG. 9 is a functional block diagram of an example wireless communication device 900 configured for power control. The wireless communication device 900 may include a receiver 905, a processing system 910, and a transmitter 915. The processing system 910 may include a power control component 924. The receiver 905, the processing system 910, the transmitter 915 and/or the power control component 924 may be configured to receive a first frame from an access point that includes a power control command 950 to be used by the wireless communication device 900 for MU-MIMO UL transmission or OFDMA UL transmission. The power control command for the wireless communication device 900 may be different (or separate) from other power control commands for other stations associated with the access point. The processing system 910 and/or the power control component 924 may be configured to determine 960 a transmit power to transmit a second frame to the access point based on the received power control command. The processing system 910, the transmitter 915, and/or the power control component 924 may be configured to transmit the second frame (e.g., a data frame 970) based on the determined transmit power. In one aspect, the power control command may indicate at least one of a target RSSI expected at the access point, an SNR correction to be applied at the wireless communication device 900, or a link margin. In another aspect, the first frame may be a trigger frame 940. The trigger frame may include the target RSSI at the access point and a second transmit power used by the access point to transmit the trigger frame. In another configuration, the processing system 910 and/or the power control component 924 may be configured to determine transmit power by computing a downlink path loss between the access point and the wireless communication device 900 and adding the measured downlink path loss to the target RSSI. In this configuration, the transmit power can be a sum of the measured downlink path loss and the target RSSI. In one configuration, the power control component 924 and/or the processing system 910 may be configured to compute downlink path loss comprising measuring an RSSI of the trigger frame and subtracting the measured RSSI from the second transmit power used. by the access point to transmit the trigger frame. In this configuration, downlink path loss can be a difference between the second transmit power and the measured RSSI. In another embodiment, the power control component 924 , the processing system 910 , and/or the transmitter 915 may be configured to transmit power information 930 to the access point. The power information may include at least one free space information, floor boost information, a current transmit power associated with an MCS, a maximum transmit power associated with the MCS, a station minimum transmit power, or backoff values. associated with each MCS. In this configuration, the power control command in the first message may be based on the transmitted power information.

[0082] The receiver 905, the processing system 910, the power control component 924, and/or the transmitter 915 may be configured to perform one or more functions discussed above with respect to blocks 805, 810, 815, and 820 of FIG. . 8. Receiver 905 may correspond to receiver 712. Processing system 910 may correspond to processor 704. Transmitter 915 may correspond to transmitter 710. Power control component 924 may correspond to power control component 126 and/or to the power control component 724.

[0083] In one configuration, the wireless communication device 900 includes means for receiving a first frame from an access point that includes a power control command to be used by the wireless communication device 900 for MU-MIMO transmission. UL or OFDMA UL. The power control command for the wireless communication device 900 may be different (or separate) from other power control commands for other stations associated with the access point. The wireless communication device 900 may include means for determining a transmit power to transmit a second frame to the access point based on the received power control command. The wireless communication device 900 may include means for transmitting the second frame based on the determined transmit power. In one aspect, the power control command may indicate at least one of a target RSSI expected at the access point, an SNR correction to be applied at the wireless communication device 900, or a link margin. In another aspect, the first frame may be a trigger frame. The trigger frame may include the target RSSI at the access point and a second transmit power used by the access point to transmit the trigger frame. In another embodiment, the means for determining transmit power may be configured to compute a downlink path loss between the access point and the wireless communication device 900 and to add the measured downlink path loss to the RSSI. target.In this configuration, the transmit power can be a sum of the measured downlink path loss and the target RSSI. In one configuration, the means for determining transmit power may be configured to compute downlink path loss by measuring an RSSI of the trigger frame and subtracting the measured RSSI from the second transmit power used by the access point to transmit the frame. shooting. In this configuration, the downlink path loss can be a difference between the second transmit power and the measured RSSI. In another embodiment, the wireless communication device 900 may include means for transmitting power information to the access point. The power information may include at least one free space information, floor boost information, a current transmit power associated with an MCS, a maximum transmit power associated with the MCS, a station minimum transmit power, or backoff values. associated with each MCS. In this configuration, the power control command in the first message may be based on the transmitted power information.

[0084] For example, the means for receiving a first frame may include the processing system 910, the power control component 924 and/or the receiver 905. Means for determining a transmit power may include the processing system 910 and /or the power control component 924. The means for transmitting the second frame may include the processing system 910, the power control component 924 and/or the transmitter 915. Means for transmitting power information may include the power control system 924. processing 910, the power control component 924 and/or the transmitter 915. The various operations of the methods described above may be performed by any suitable means capable of performing the operations, such as various hardware and/or software components, circuits and /or module(s). Generally, any operations illustrated in the Figures can be performed by corresponding functional means capable of performing the operations.

[0085] The various illustrative logic blocks, components and circuits described in connection with the present disclosure may be implemented or executed with a general purpose processor, a DSP, an application specific integrated circuit (ASIC), an FPGA or other PLD, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but alternatively, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0086] In one or more aspects, the described functions can be implemented in hardware, software, firmware or any combination thereof. If implemented in software, functions can be stored or transmitted as one or more instructions or code in a computer-readable medium. Computer-readable media includes computer storage media and communications media, including any medium that facilitates the transfer of a computer program from one place to another. A storage medium can be any available media that can be accessed by a computer. By way of example and not limitation, such computer-readable media may comprise RAM, ROM, EEPROM, compact disk (CD)-ROM (CD-ROM) or other optical disk storage, magnetic disk storage or other storage devices magnetic, or any other medium that can be used to transport or store the desired program code in the form of instructions or data structures and that can be accessed by a computer. Furthermore, any connection is properly called computer-readable media. For example, if software is transmitted from a site, server, or other remote source using a coaxial cable, fiber-optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, the cable coaxial, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of media. Disk and disc, as used herein, includes CD, laser disc, optical disc, digital versatile disc (DVD), floppy disk, and Blu-ray disc where discs generally reproduce data magnetically, while discs reproduce data optically with lasers. Thus, computer-readable medium comprises a non-transitory computer-readable medium (e.g., tangible medium).

[0087] The methods disclosed herein comprise one or more steps or actions to achieve the method described. The steps and/or actions of the method can be interchanged with each other without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

[0088] Thus, certain aspects may comprise a computer program product to perform the operations presented herein. For example, such a computer program product may comprise a computer-readable medium with stored (and/or encoded) instructions, the instructions being executable by one or more processors to perform the operations described herein. For certain aspects, the computer program product may include packaging material.

[0089] Furthermore, it should be appreciated that components and/or other means appropriate for carrying out the methods and techniques described herein may be downloaded and/or otherwise obtained by a user terminal and/or base station, as applicable. For example, such a device may be coupled to a server to facilitate the transfer of means to perform the methods described herein. Alternatively, various methods described herein may be provided via storage media (e.g., RAM, ROM, a physical storage medium such as a CD or floppy disk, etc.), such that a user terminal and/or station base can achieve the various methods when docking or providing the storage media to the device. Furthermore, any other technique suitable for providing the methods and techniques described herein to a device may be used.

[0090] It should be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, alterations and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

[0091] Although the foregoing is directed to aspects of the present disclosure, other and other aspects of the disclosure may be conceived without departing from its basic scope, and its scope is determined by the claims that follow.

[0092] The foregoing description is provided to enable anyone skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Accordingly, the claims are not intended to be limited to the aspects shown herein, but are to be in accordance with the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one " unless specifically stated so, but rather "one or more". Unless specifically indicated otherwise, the term "some" refers to one or more. All structural and functional equivalents of the elements of the various aspects described throughout this description that are known or that are subsequently known to those skilled in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No element of a claim shall be construed under the provisions of 35 U.S.C. §112(f) unless the element is expressly recited using the expression "means to" or, in the case of a method claim, the element is recited using the phrase "step to".

Claims (15)

1. Method of wireless communication by an access point (104), characterized by the fact that it comprises: determining (510) a power control command (310) to a station (112, 114, 116, 118) that enables multi-input, multiple-output, MIMO, multi-user, MU, uplink, UL, MU-MIMO UL transmission (220), or UL orthogonal frequency division multiple access transmission (220), OFDMA UL, in a wireless local area network, WLAN, the power control command (310) being associated with a station identifier (318) identifying the station (112, 114, 116, 118) for which the power control command ( 310) is intended, wherein the power control command (310) indicates a received signal strength indicator, RSSI, expected target at the access point (104); and transmitting (515) a frame (210) to the station (112, 114, 116, 118) identified by the station identifier, wherein the frame (210) includes the power control command (310) determined for MU transmission. MIMO UL or OFDMA UL transmission and the station identifier (318), wherein the frame (210) is a trigger frame (210), which comprises the target RSSI and a transmit power level used by the access point (104 ) to transmit the trigger frame (210). 2. Method according to claim 1, characterized by the fact that the target RSSI and the transmit power level enable the station (112, 114, 116, 118) to compute a transmit power for transmitting (220) MU -MIMO UL or OFDMA UL transmission (220), and wherein the target RSSI is provided in a subfield of a plurality of user information fields within the trigger frame (220) and the transmit power level is provided in a common information field of the trigger frame (210). 3. Method, according to claim 1, characterized by the fact that the target RSSI indicates an average RSSI over a set of antennas associated with the access point (104). 4. Method according to claim 1, characterized by the fact that the trigger frame (210) is intended for a plurality of stations (112, 114, 116, 118), and the trigger frame (210) comprises a separate power control command (310) for each station (112, 114, 116, 118) among the plurality of stations (112, 114, 116, 118). 5. Method according to claim 1, characterized by the fact that it further comprises receiving power information associated with the station (112, 114, 116, 118), wherein the power information comprises a free space value, wherein the free space value corresponds to a maximum increase in power control command (310). 6. Method, according to claim 5, characterized by the fact that the power information additionally comprises a flag indicating whether the station (112, 114, 116, 118) is transmitting at a minimum transmission power associated with an index of modulation and coding scheme, MCS, and wherein the power control command (310) is not decreased when the station (112, 114, 116, 118) is transmitting at minimum transmit power. 7. Method according to claim 1, characterized by the fact that the power control command (310) is directed to a single station (112, 114, 116, 118) performing transmissions (220) MU-MIMO UL or OFDMA UL in a wireless local area network. 8. Method according to claim 1, characterized by the fact that it further comprises receiving a second frame (210) from the station (112, 114, 116, 118) based on a received signal strength indicator, RSSI , target and a transmit power level transmitted in the frame (210). 9. Method of wireless communication by a station (112, 114, 116, 118), characterized in that it comprises: receiving (810) a first frame (210) from an access point (104) that includes a power control command (310) to be used by the station (112, 114, 116, 118) for transmission (220) of multiple inputs and multiple outputs, MIMO, multiuser, MU, uplink, UL, MU-MIMO UL, or UL orthogonal frequency division multiple access transmission (220), OFDMA UL, in a wireless local area network, WLAN, and includes a station identifier (318) identifying the station (112, 114, 116 , 118) and associated with the power control command (310), wherein the power control command (310) indicates an indicator of received signal strength, RSSI, expected target at the access point (104) and wherein the first frame (210) is a trigger frame (210), which comprises the target RSSI and a transmit power level used by the access point (104) to transmit the trigger frame (210); determining (815) a transmit power to transmit a second frame (210) to the access point (104) based on the received power control command (310); and transmitting (820) the second frame (210) based on the determined transmit power. 10. Method according to claim 9, characterized by the fact that determining the transmission power comprises: computing a downlink path loss between the access point (104) and the station (112, 114, 116, 118 ); and adding the measured downlink path loss to the target RSSI, wherein the transmit power is a sum of the measured downlink path loss and the target RSSI. 11. The method of claim 10, wherein computing downlink path loss comprises: measuring an RSSI of the trigger frame (210); and subtracting the measured RSSI from the second transmit power used by the access point (104) to transmit the trigger frame, wherein the downlink path loss is a difference between the second transmit power and the measured RSSI. 12. Method according to claim 9, characterized by the fact that it further comprises: transmitting (805) power information to the access point (104), wherein the power information includes at least one of free space information , increase information about floor, a current transmit power associated with a modulation and coding scheme, MCS, a maximum transmit power associated with the MCS, minimum transmit power of the station (112, 114, 116, 118), or values of BACKOFF associated with each MCS, wherein the power control command (310) in the first frame (210) is based on the transmitted power information. 13. Access point (104) for wireless communication, characterized in that it comprises: means for determining a power control command (310) to a station (112, 114, 116, 118) that allows transmission (220) multi-input multiple-output, MIMO, multi-user, MU, uplink, UL, MU-MIMO UL, or UL orthogonal frequency division multiple access (220) broadcast, OFDMA UL, in a local area network wireless, WLAN, the power control command (310) being associated with a station identifier (318) that identifies the station (112, 114, 116, 118) to which the power control command (310) is directed. intended, wherein the power control command (310) indicates a received signal strength indicator, RSSI, expected target at the access point (104); and means for transmitting a frame (210) to the station (112, 114, 116, 118) identified by the station identifier (112, 114, 116, 118), wherein the frame (210) includes the power control command (310) determined for MU-MIMO UL transmission or OFDMA UL transmission and the station identifier (318), and wherein the frame (210) is a trigger frame (210), comprising the target RSSI and a power level transmission method used by the access point (104) to transmit the trigger frame (210). 14. Station for wireless communication, characterized by the fact that it comprises: means for receiving a first frame (210) from an access point (104) that includes a power control command (310) to be used by the station (112, 114, 116, 118) for multi-input multiple-output, MIMO, multi-user, MU, uplink, UL, MU-MIMO UL transmission (220), or data division multiple access transmission (220) orthogonal frequency of UL, OFDMA UL, in a wireless local area network, WLAN, and includes a station identifier (318) identifying the station (112, 114, 116, 118) and associated with the power control command (310 ), wherein the power control command (310) indicates an indicator of received signal strength, RSSI, expected target at the access point (104) and wherein the first frame (210) is a trigger frame (210) , which comprises the target RSSI and a transmit power level used by the access point (104) to transmit the trigger frame (210); means for determining a transmit power for transmitting a second frame (210) to the access point (104) based on the received power control command (310); and means for transmitting the second frame (210) based on the determined transmit power. 15. Computer-readable memory characterized by the fact that it comprises instructions stored therein which, when executed, cause a computer to perform the method as defined in any one of claims 1 to 12.