HK1199778B - Systems and methods for generating and decoding short control frames in wireless communications - Google Patents

Description

System and method for generating and decoding short control frames in wireless communications

This application claims priority from provisional U.S. application S/n.61/581,254 entitled "SYSTEMS AND METHODS for generating AND DECODING SHORT CONTROL frames" filed on 29.12.2011, which is assigned to the assignee of this application AND is incorporated herein by reference in its entirety. The present application further claims priority from provisional U.S. application S/n.61/591,530 entitled "SYSTEMS AND METHODS FOR GENERATING AND DECODINGSHORT CONTROL frames FRAMES IN WIRELESS COMMUNICATIONS (system and method FOR generating and decoding short CONTROL frames in wireless COMMUNICATIONS)" filed on month 1, month 27, 2012, which is assigned to the assignee of the present application and is incorporated herein by reference in its entirety. The present application further claims priority from provisional U.S. application S/n.61/605,900 entitled "SYSTEMS AND METHODS FOR GENERATING AND DECODING SHORT CONTROL frames" filed on 12/3/2012, assigned to the assignee of the present application and incorporated herein by reference in its entirety. The present application further claims priority from provisional U.S. application S/n.61/648,510 entitled "system and method for generating and DECODING SHORT CONTROL frames in wireless COMMUNICATIONS" filed on day 5, month 17, 2012, assigned to the assignee of the present application and incorporated herein by reference in its entirety. The present application further claims priority from provisional U.S. application S/n.61/691,066 entitled "SYSTEMS AND METHODS FOR GENERATING and decoding SHORT CONTROL frames FRAMES IN WIRELESS COMMUNICATIONS" filed on 8/20/2012, assigned to the assignee of the present application and incorporated herein by reference in its entirety. The present application further claims priority from provisional U.S. application S/n.61/731,426 entitled "SYSTEMS AND METHODS FOR GENERATING AND DECODING SHORT sequences IN WIRELESS COMMUNICATIONS" filed on 29/11/2012, assigned to the assignee of the present application and incorporated herein by reference in its entirety.

Background

FIELD

The present application relates generally to wireless communications, and more particularly to systems, methods, and devices for communicating short control frames.

Background

In many telecommunication systems, a communication network is used to exchange messages between several spatially separated interacting devices. Networks may be classified according to geographic scope, which may be, for example, a city area, a local area, or a personal area. Such networks may be designated as Wide Area Networks (WANs), Metropolitan Area Networks (MANs), Local Area Networks (LANs), or Personal Area Networks (PANs), respectively. The network also differs according to the switching/routing technology used to interconnect the various network nodes and devices (e.g., circuit-switched-packet-switched), the type of physical medium used for transmission (e.g., wired-wireless), and the communication protocol suite being used (e.g., internet protocol suite, SONET (synchronous optical networking), ethernet, etc.).

Wireless networks tend to be preferred when network elements are mobile and thus have dynamic connectivity requirements, or where the network architecture is formed in an ad hoc (ad hoc) topology rather than a 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.

Devices in a wireless network may transmit/receive information between each other. This information may include packets, which may be referred to in some aspects as data units. The packet may include a control frame. Control frames with control information and payload data may result in significant overhead and increased processing latency for the receiving device. Thus, there is a need for systems, methods, and non-transitory computer-readable media for reducing network and processing overhead.

SUMMARY

The system, method, and apparatus of the present invention each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of the invention as expressed by the claims which follow, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled "detailed description" one will understand how the features of this invention provide advantages that include reducing the size of control frames.

One aspect of the present disclosure provides a wireless communication method. The method includes generating a control frame including a physical layer preamble having a signal field including an indicator indicating that the control frame is a control frame type frame. The method further includes transmitting the control frame.

Another aspect of the disclosure provides a wireless device comprising a processor configured to generate a control frame comprising a physical layer preamble having a signal field comprising an indicator indicating that the control frame is a frame of a control frame type. The wireless device further includes a transmitter configured to transmit the control frame.

Another aspect of the present disclosure provides a wireless device comprising means for generating a control frame comprising a physical layer preamble having a signal field comprising an indicator indicating that the control frame is a control frame type frame. The wireless device further includes means for transmitting the control frame.

Another aspect of the disclosure provides a computer program product comprising a computer readable medium. The computer-readable medium includes code for generating a control frame including a physical layer preamble having a signal field including an indicator indicating that the control frame is a control frame type of frame. The computer-readable medium further includes code for transmitting the control frame.

Brief Description of Drawings

Fig. 1 illustrates an example of a wireless communication system in which aspects of the present disclosure may be employed.

Fig. 2 illustrates various components that may be utilized in a wireless device that may be utilized within the wireless communication system of fig. 1.

Fig. 3 illustrates an example of a control frame that may be generated and communicated in the system of fig. 1.

Fig. 4 illustrates another example of a control frame that may be generated and communicated in the system of fig. 1.

Fig. 5 illustrates another example of a control frame that may be generated and communicated in the system of fig. 1.

Fig. 6 is a table illustrating fields that may be included in a SIG field of an example of an ACK frame.

Fig. 7 is a table illustrating fields that may be included in a SIG field of another example of an ACK frame.

Fig. 8 illustrates another example of an ACK frame having a similar format as the control frame of fig. 5.

Fig. 9 illustrates a flow diagram of an aspect of an exemplary method for generating and transmitting control frames.

Fig. 10 is a functional block diagram of an exemplary wireless device that may be employed within the wireless communication system of fig. 1.

Fig. 11 illustrates a flow diagram of an aspect of an exemplary method for receiving and processing control frames.

Fig. 12 is a functional block diagram of an exemplary wireless device that may be employed within the wireless communication system of fig. 1.

Fig. 13 illustrates an example of a PS-poll frame.

Fig. 14 illustrates an example of an ACK frame.

Fig. 15 illustrates an example of an RTS frame.

Fig. 16 illustrates an example of a CTS frame.

Fig. 17 illustrates an example of a block ACK frame.

Detailed Description

Various aspects of the novel systems, devices, and methods are described more fully hereinafter with reference to the accompanying drawings. This summary disclosure may, however, be embodied 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 will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Based on the teachings herein one skilled in the art should appreciate that the scope of the present disclosure is intended to cover any aspect of the novel systems, devices, and methods disclosed herein, whether implemented independently or in combination with any other aspect of the present invention. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. Moreover, the scope of the present application is intended to cover apparatuses or methods practiced using other structure, functionality, or structure and functionality in addition to or other than the various aspects of the present invention set forth herein. It should be understood that any aspect disclosed herein may be implemented by one or more elements of a claim.

Although specific aspects are described herein, numerous variations and permutations of these aspects fall within the scope of the present disclosure. Although some benefits and advantages of the preferred aspects are mentioned, the scope of the present disclosure is not intended to be limited to a particular benefit, use, or objective. 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 the 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 equivalents thereof.

Wireless network technologies may include various types of Wireless Local Area Networks (WLANs). WLANs may be used to interconnect nearby devices together using widely used networking protocols. The various aspects described herein may be applied to any communication standard, such as WiFi, or more generally any member of the IEEE802.11 family of wireless protocols. For example, the various aspects described herein may be used as part of the IEEE802.11ah protocol using the sub-1 GHz band.

In some aspects, wireless signals in the sub-gigahertz band may be transmitted according to the 802.11ah protocol using Orthogonal Frequency Division Multiplexing (OFDM), Direct Sequence Spread Spectrum (DSSS) communications, a combination of OFDM and DSSS communications, or other schemes. Implementations of the 802.11ah protocol may be used for sensors, metering, and smart grids. Advantageously, aspects of certain devices implementing the 802.11ah protocol may consume less power than devices implementing other wireless protocols and/or may be used to transmit wireless signals across relatively long distances (e.g., about 1 kilometer or more).

In some implementations, a WLAN includes various devices that are components of an access wireless network. For example, there may be two types of devices: an access point ("AP") and a client (also referred to as a station, or "STA"). Generally, the AP serves as a hub or base station for the WLAN, while the STA serves as a user of the WLAN. For example, the STA may be a laptop computer, a Personal Digital Assistant (PDA), a mobile phone, and the like. In one example, the STAs connect to the AP via a wireless link that conforms to WiFi (e.g., IEEE802.11 protocol such as 802.11ah) to obtain general connectivity to the internet or to other wide area networks. In some implementations, the STA may also be used as an AP.

An access point ("AP") may also include, be implemented as, or be referred to as a node B, a radio network controller ("RNC"), an evolved node B, a base station controller ("BSC"), a base transceiver station ("BTS"), a base station ("BS"), a transceiver function ("TF"), a radio router, a radio transceiver, or some other terminology.

A station ("STA") may also include, be implemented as, or be referred to as an access terminal ("AT"), a subscriber station, a subscriber unit, a mobile station, a remote terminal, a user agent, a user device, user equipment, or some other terminology. In some implementations, an access terminal may comprise a cellular telephone, a cordless telephone, a session initiation protocol ("SIP") phone, a wireless local loop ("WLL") station, a personal digital assistant ("PDA"), a handheld device having wireless connection capability, or some other suitable processing device connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a phone (e.g., a cellular phone or smart phone), a computer (e.g., a laptop), a portable communication device, a handset, a portable computing device (e.g., a 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 suitable device configured to communicate via a wireless medium.

As discussed above, certain devices described herein may implement, for example, the 802.11ah standard. Such devices (whether functioning as STAs or APs or other devices) may be used for smart metering or in smart grids. Such devices may provide sensor applications or be used in home automation. These devices may alternatively or additionally be used in a healthcare environment, for example for personal healthcare. These devices may also be used for supervision to enable extended range internet connectivity (e.g., for use with hotspots), or to enable machine-to-machine communication.

Fig. 1 illustrates 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, such as the 802.11ah standard. The wireless communication system 100 may include an AP104 in communication with STAs 106.

Various procedures and methods may be used for transmissions between the AP104 and the STA106 in the wireless communication system 100. For example, signals may be transmitted and received between the AP104 and the STAs 106 according to 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 transmitted and received between the AP104 and the STA106 according to CDMA techniques. If this is the case, the wireless communication system 100 may be referred to as a CDMA system.

The communication link that facilitates transmission from AP104 to one or more STAs 106 may be referred to as Downlink (DL)108, while the communication link that facilitates transmission from one or more STAs 106 to AP104 may be referred to as Uplink (UL) 110. Alternatively, downlink 108 may be referred to as the forward link or forward channel, and uplink 110 may be referred to as the reverse link or reverse channel.

AP104 may provide wireless communication coverage in a Basic Service Area (BSA) 102. The AP104, along with STAs 106 associated with the AP104 and communicating using the AP104, 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 AP104, but may function as a peer-to-peer network between STAs 106. Accordingly, the functions of the AP104 described herein may alternatively be performed by one or more STAs 106.

Fig. 2 illustrates various components that may be employed in a wireless device 202 that may be employed within the wireless communication system 100. Wireless device 202 is an example of a device that may be configured to implement the various methods described herein. For example, the wireless device 202 may include the AP104 or one of the STAs 106.

The wireless device 202 may include a processor 204 that controls the operation of the wireless device 202. The processor 204 may also be referred to as a Central Processing Unit (CPU). Memory 206, which may include both Read Only Memory (ROM) and Random Access Memory (RAM), provides instructions and data to the processor 204. A portion of the memory 206 may also include non-volatile random access memory (NVRAM). The processor 204 typically performs logical and arithmetic operations based on program instructions stored within the memory 206. The instructions in the memory 206 may be executable to implement the methods described herein.

The processor 204 may include or be a component of a processing system implemented with one or more processors. The one or more processors may be implemented with any combination of general purpose microprocessors, microcontrollers, Digital Signal Processors (DSPs), Field Programmable Gate Arrays (FPGAs), Programmable Logic Devices (PLDs), controllers, state machines, gated logic, discrete hardware components, dedicated hardware finite state machines, or any other suitable entity capable of performing a calculus or other manipulation of information.

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

The wireless device 202 may also include a housing 208, and the housing 208 may contain a transmitter 210 and a receiver 212 to allow transmission and reception of data between the wireless device 202 and a remote location. The transmitter 210 and receiver 212 may be combined into a transceiver 214. An antenna 216 may be attached to the housing 208 and electrically coupled to the transceiver 214. The wireless device 202 may also include (not shown) multiple transmitters, multiple receivers, multiple transceivers, and/or multiple antennas.

The wireless device 202 may also include a signal detector 218 that may be used in an effort to detect and quantify the level of signals received by the transceiver 214. The signal detector 218 may detect signals such as total energy, energy per subcarrier per symbol, power spectral density, and other signals. The wireless device 202 may also include a Digital Signal Processor (DSP)220 for use in processing signals. DSP220 may be configured to generate data units for transmission. In some aspects, the data unit may comprise a physical layer data unit (PPDU). In some aspects, the PPDU is referred to as a packet.

In some aspects, the wireless device 202 may further include a user interface 222. The user interface 222 may include a keypad, a microphone, a speaker, and/or a display. User interface 222 may include any element or component that conveys information to a user of wireless device 202 and/or receives input from the user.

The various components of the wireless device 202 may be coupled together by a bus system 226. The bus system 226 may include, for example, a data bus, as well as a power bus, a control signal bus, and a status signal bus in addition to the data bus. Those skilled in the art will appreciate that the components of the wireless device 202 may be coupled together or use some other mechanism to accept or provide input to each other.

Although several separate components are illustrated in fig. 2, those skilled in the art will recognize that one or more of these components may be combined or implemented collectively. For example, the processor 204 may be used to implement not only the functionality described above with respect to the processor 204, but also the functionality described above with respect to the signal detector 218 and/or the DSP 220. In addition, each of the components illustrated in fig. 2 may be implemented using a plurality of separate elements.

As discussed above, the wireless device 202 may include an AP104 or STA106 and may be used to transmit and/or receive communications. The communications exchanged between devices in a wireless network may include data units that may include packets or frames. In some aspects, a data unit may include three types of frames, including a data frame, a control frame, and a management frame. The data frame may be used to transmit data from the AP and/or STA to other APs and/or STAs. The control frames may be used with data frames to perform various operations and to reliably deliver data (e.g., acknowledge receipt of data, polling of APs, zone clearing operations, channel acquisition, carrier sense maintenance functions, etc.). The management frames may be used for various supervisory functions (e.g., for joining and leaving a wireless network, etc.).

As discussed above, the DSP220 and/or the processor 204 may be configured to generate the data unit for transmission. In some aspects, the generated data unit may comprise a control frame comprising control information and optionally a plurality of data symbols. The control frame may be used to assist in the delivery of data frames and may be included in a Medium Access Control (MAC) header. Including a control frame with control information and data symbols (e.g., payload data) in the MAC header may result in significant overhead and increased processing latency for the receiving device. For example, the control frame may include protocol information, control type information, address information, payload data, and the like. In some aspects, the information included in the control frame may not always be necessary for a particular use of the control frame. Thus, there is a need for systems, methods, and non-transitory computer-readable media for generating and decoding short control frames. For example, short control frames may be generated by omitting certain information from the control frame and/or by including the control frame in other packet locations, such as a physical layer (PHY) preamble. For example, the control frame may include a physical layer (PHY) preamble including a plurality of fields. For example, the fields may include one or more training fields (e.g., a Short Training Field (STF) and a Long Training Field (LTF)) and a Signal (SIG) field. Each of these training fields may comprise a known sequence of bits or symbols. In some aspects, the SIG field may include information about the data unit, such as a description of the length or data rate of the data unit (e.g., a length field, a Modulation Coding Scheme (MCS) field, a Bandwidth (BW) field, etc.). In some aspects, the short control frame may be generated by encoding the control frame in the SIG field of the PHY preamble.

Fig. 3 illustrates an example of a control frame 300 that may be generated and communicated in the system of fig. 1. As shown, the control frame 300 includes an STF field 305, and LTF field 310 and a control SIG field 315. For example, the control frame 300 may be a PHY preamble. In some aspects, the PHY preamble may include a Physical Layer Convergence Protocol (PLCP) layer, as defined in the IEEE802.11 specification. The STF field 305 includes one or more STFs. The LTF field 310 includes one or more LTFs. The control information of the control frame 300 may be included in the SIG field 315. Further, in some aspects, the control frame may not include any additional fields or data (e.g., payload). As a result, network overhead may be reduced and throughput and processing of data packets may be increased.

Fig. 4 illustrates another example of a control frame 400 that may be generated and communicated in the system of fig. 1. As shown, the control frame 400 includes an STF field 405, and LTF field 410, a control SIG field 415, and a control extension field 420. Similar to the control frame 300, the STF field 405 includes one or more STFs and the LTF field 410 includes one or more LTFs. Further, similar to the control frame 300, the control information of the control frame 400 may be included in the SIG field 415. However, unlike the control frame 300, additional control information may be included in the control extension field 420. For example, the STF field 405 and LTF field 410, the control SIG field 415 may be included in the PHY preamble of the control frame 400. However, there may be additional control information that is not suitable for placement in the PHY preamble of the control frame 400. Accordingly, a portion (e.g., a small number of symbols) of the data portion of the control frame 400 may be used as the control extension field 420 to include additional control information. The control extension field 420 of the control frame 400 may be sent with a default MCS, which may be predetermined or negotiated in different messages between the transmitter and receiver (e.g., at association or in a beacon). In an aspect, the MCS of the control extension field 420 may be indicated in the SIG field 415. Both control frame 300 and control frame 400 may be used for communication. For example, the control frame 300 may be used in situations where control information fits in the SIG field 315. Further, the control frame 400 may be used in situations where control information is not appropriate to be placed in the SIG field 315. In some aspects, the length field of the SIG field may further indicate whether a control extension field is included in the control frame.

Fig. 5 illustrates another example of a control frame 500 that may be generated and communicated in the system of fig. 1. As shown, the control frame 500 includes an STF field 505, and LTF field 510, SIG field 515, service field 520, Frame Control (FC) field 525, control Information (INFO) field 530, and Frame Check Sequence (FCs) field 535. The control information of the control frame 500 may be included in the control information field 530.

The type of control information included in any of the above control frames 300, 400, and 500 (or any other suitable control frame) may depend on the type of control frame. For example, various different control frames may be generated and communicated by the wireless device 202. The different types of control frames used in the wireless system of fig. 1 may include one or more of the following control frame types: acknowledgement (ACK), power save poll (PS-poll), Request To Send (RTS), Clear To Send (CTS), Block ACK Request (BAR), block ACK (ba), contention free end (CF-end), CF-end poll, MCS request, MCS response, Null Data Packet (NDP), probe request, and probe response. The control information may include an information field. Different control frame types may include different information fields. Various information fields are described herein that may be included in different types of control frames. It should be noted that the fields described below do not necessarily need to be included in the control frame in the same order as described. Rather, the fields may be included in any order or in any portion of a control frame containing control information (e.g., SIG field, control extension field, control field, etc.). For example, the fields may be ordered by priority. However, the order of the fields of a given control frame type may be predetermined (e.g., programmed at device manufacture or upon initialization of the device, communicated in separate messages between wireless devices 202) so that the wireless devices 202 have information about which bits in the control frame correspond to which fields.

In some aspects, certain fields may be included in all control frames, regardless of type. For example, in some aspects, a type field may be included in all control frames, where the type field identifies the type of control frame. The type field may be, for example, 2, 3, or 4 bits long. The interpretation of the remaining bits in the control frame (e.g., determining which bits correspond to which fields and which fields are included) may be based on the type of control frame and whether the frame is even a control frame. For example, in some aspects, a value of 0 for the length field of the SIG field of a frame may indicate that the frame is a short control frame, such as control frame 300 or 400. If the length field has different values, it may indicate that the frame is of a different type (e.g., a data frame, a management frame, or a different type of control frame). The SIG field may further include a type field that subsequently indicates the type of the control frame. In some other aspects, any value of the length field of the SIG field of a frame that is less than a particular value (e.g., 10) may indicate that the frame is a control frame, such as control frame 300 or 400. Further, the type of control frame may be based on the value of the length field, meaning that each value 0-10 may be associated with a different control frame type. In some other aspects, a 1-bit type field may be added to the frame, the 1-bit type field generally indicating whether the frame is a control frame (or in particular, a short format control frame), such as control frames 300 or 400, or other frames (e.g., data frames, management frames, or different types of control frames), depending on the value of the bit. In some other aspects, one or more reserved field values defined in each frame may be used to indicate whether the frame is a control frame (or, in particular, a short format control frame), such as control frame 300 or 400, or other frames (e.g., data frames, management frames, or different types of control frames). For example, one or more reserved values of the MCS field in the SIG field may be used to indicate whether the frame is a control frame and/or a control frame type. In this case, a further field indicating the type may not be required. For example, an unused value of a Space Time Block Code (STBC) field may be used. Multiple fields may also be used in combination to identify the control frame. The length and MCS may also be used in combination to indicate the type of control frame. For example, the length field may have a value (e.g., 0) that may indicate that the frame is of a certain type (e.g., NDP), while a different value (e.g., length >0) of the length field may indicate that the type of control frame is indicated by the MCS.

Similarly, a 1-bit type field may be used in conjunction with a length field to indicate the type of control frame. For example, a value of a 1-bit type field (e.g., 0) may indicate that the frame is a control frame of a type other than a particular type (e.g., NDP). Further, another value (e.g., 1) of the 1-bit type field may indicate that the frame is of a certain type (e.g., NDP) if the length field has a certain value (e.g., 0), or another value (e.g., 1) of the 1-bit type field may indicate that the frame is not a control frame if the length field has a different value (e.g., length > 1).

Further, in some aspects, a Cyclic Redundancy Check (CRC) field may be included in all types of control frames. The CRC field may be used to verify that the frame was received correctly. The CRC may be, for example, 4 or 5 bits long. Further, in some aspects, a Transmit (TX) power indication may be included in all types of control frames. The TX power indication may be used by the receiver of the control frame to estimate the path loss or to change the behavior of the receiver based on the TX power of the transmitter of the control frame.

Further, in some aspects, a non-valid combination of one or across values in more than one field within the SIG field may be used to indicate whether the frame is a control frame. For example, the encoding field may include two subfields (e.g., one bit each). A first subfield of the encoding field may indicate a type of encoding (e.g., Binary Convolutional Coding (BCC) or Low Density Parity Check (LDPC) coding). The second subfield of the encoding field may indicate how to calculate the length of the frame. For example, when the first subfield indicates a BCC coding type, the second subfield can be set to 0. A value of 01 in the encoded field is not valid for a normal non-control frame and therefore a value of 01 may be used to indicate that the frame is a control frame. Similar procedures may be applied to other fields or combinations of fields in the SIG field. In addition, the short control frame will include a type field that identifies the type of control frame.

In some aspects, the control frame may be transmitted with a PHY preamble occupying 1 or 2 MHz. The bandwidth of the frame may be implicitly determined from the PHY preamble structure. For example, the STF and/or LTF of the PHY preamble may be used to determine whether the bandwidth of the frame is 1MHz or 2 MHz.

In some aspects, the control frame may be replicated across multiple 1 or 2MHz bandwidth channels, e.g., multiple copies of the control frame may be transmitted on multiple channels, which may or may not be contiguous. The receiver of such a control frame can determine on how many channels the frame is duplicated. In an aspect, an information field or SIG field of a PHY preamble of a control frame may include an indication of a channel bandwidth or total number of channels over which the frame is duplicated. For example, 2 bits of the information field or SIG field may be used as follows:

frames of-00 are not duplicated

-01: replication over 2 channels

-10: replication over 4 channels

-11: replication over 8 channels

Where a "channel" may be a 1MHz or 2MHz bandwidth channel depending on whether the frame is a 1MHz or 2MHz bandwidth frame.

In some aspects, one type of control frame is an ACK. For example, STA106a may send data to AP 104. Upon successful receipt of the data, the AP104 may send an ACK to the STA106a indicating successful receipt of the data to the STA106 a. In some aspects, the ACK may be sent in response to successful receipt of at least one of: data frames, management frames, control frames, PS-polls, or another type of frame. In one aspect, the control information for the ACK may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: an address, an identifier of an acknowledged packet, an indication of rate control, an indication of buffered data, a duration, and a doppler indication. In an aspect, the duration field may be 9 bits or less and may be used to update a Network Allocation Vector (NAV). In another aspect, the ACK may be sent as a response to a trigger frame (e.g., PS-poll or QoS (quality of service) null), in which case the duration field may indicate the data delivery time the AP has available buffer units for that particular STA. In some aspects, the duration may be expressed in milliseconds or in multiples of a unit of time (e.g., a time slot or a predefined value agreed upon by the AP and the STA during association, re-association, or transmitted with a management frame). The control information (e.g., information field, control information field, etc.) of the ACK may not include any additional fields.

In some aspects, the address field of the ACK may include one or more global addresses (e.g., MAC address, BSSID) that uniquely identify the transmitter and/or receiver of the ACK globally (e.g., in most any network). In some aspects, the address field may include one or more local addresses (e.g., Association Identifiers (AIDs)) that uniquely identify the transmitter and/or receiver of the ACK locally (e.g., in a local network, such as in a particular BSS). In some aspects, the address field may include a partial or non-unique identifier (e.g., a portion of a MAC address or AID) that identifies the transmitter and/or receiver of the ACK. For example, the address field may be one of the AID, the MAC address, or a portion of the AID or MAC address of the transmitter and/or receiver of the ACK that is duplicated from the frame acknowledged by the ACK.

In some aspects, an identifier field of the ACK may identify the frame being acknowledged (e.g., one or more MAC Protocol Data Units (MPDUs)). For example, in one aspect, the identifier field may be a hash of the contents of the frame. In another aspect, the identifier field may include all or a portion of a CRC (e.g., FCS field) of the frame. In another aspect, the identifier field may be based on all or a portion of a CRC (e.g., FCS field) of the frame or all or a portion of a local address (e.g., AID of STA). In another aspect, the identifier field may be a sequence number of the frame. In another aspect, the identifier field may be calculated in any combination based on one or more of the following: one or more global addresses of the transmitter/receiver of the ACK, one or more local addresses of the transmitter/receiver of the ACK, one or more portions of the global address of the transmitter/receiver of the ACK, or one or more portions of the local address of the transmitter/receiver of the ACK, a sequence number (or a portion of a sequence number) of one of the MPDUs acknowledged, all or a portion of a CRC (e.g., an FCS field) of the frame acknowledged, all or a portion of a scrambling seed of the frame acknowledged. For example, in an aspect, the identifier field may include a hash of a global address (e.g., BSSID, MAC address of AP) and a local address (e.g., AID of STA).

(dec(AID[0:8])+dec(BSSID[44:47]XOR BSSID[40:43])2^5)mod2^9(1)

Where dec () is a function that converts a 16-ary number to a decimal number.

In another aspect, the identifier may be a combination of a portion of the FCS of the solicited frame and a scrambling seed or value found in the service field of the solicited frame, or a sequence number of the solicited frame. For example, the combining may include a summation operation or a duplication operation of the FCS and some bits of the scrambling seed to some bits of the ACK identifier. In some aspects, the identifier included in the ACK may be different depending on the type/subtype of the solicited frame. As an example, if the solicited frame is a data frame or a management frame, the identifier may be based on the sequence number of the MPDU in the solicited frame, or if there is the necessary information in the data or management packet, it may be any other identifier described herein. If the frame is a control frame (e.g., a PS-poll), the frame may not have a sequence number and thus in this case the identifier may be based on the FCS of the PS-poll frame, the PS-poll identifier, or any other identifier for which the control frame described herein provides the necessary information based on the token number or the control frame.

In some aspects, the identifier included in the ACK may be different depending on the type/subtype of the solicited frame. As an example, if the solicited frame is a data frame or a management frame, the identifier may be based on a combination of partial sequence numbers of MPDUs in the solicited frame and any other identifier described herein where the necessary information is present in the data or management packet. The length of the partial sequence number included in the ACK ID may be a function of the maximum number of MPDUs that the block ACK frame may acknowledge. As an example, a partial sequence number of 6 bits in length is sufficient to distinguish multiple blocks of 64 MPDUs. In this regard, the ACK frame may be capable of performing block ACK functionality.

As an example, if the frame is a control frame (e.g., PS-poll), the frame does not have a sequence number and thus in this case the identifier may be based on the FCS of the PS-poll frame, or any other identifier for which the control frame described herein provides the necessary information based on the token number or the control frame. As an additional example, if the ACK is sent as a response to a PS-poll control frame defined based on the concepts described herein, the ACK identifier may be the same as the PS-poll identifier.

In some aspects, the identifier field of the ACK includes one or more bits of a Least Significant Bit (LSB) of a receiver address (e.g., address 1) of the solicited frame. The receiver address in the solicited frame may be a full MAC address or a local Address (AID), depending on the frame format. In some aspects, the identifier field of the ACK includes one or more bits in the least significant bits of the receiver address combined with (e.g., summed with some other calculation) the scrambling seed (or portion of the scrambling seed) from the service field of the solicited frame.

In some aspects, the identifier field of the ACK is the last bit or bits of the solicited frame. It should be noted that any of the examples discussed above regarding the identifier field of the ACK may be included with any suitable short control frame (such as those described herein) and in response to any frame type.

In some aspects, the frame in response to which the ACK is sent may include a token number set by the transmitter of the frame. The transmitter of the frame may generate the token number based on an algorithm. In some aspects, the token number generated by a transmitter may have a different value for each frame transmitted by the transmitter. In such an aspect, a receiver of the frame may use the token number in the identifier field of the ACK, such as by setting the identifier to the token number or calculating the identifier based at least in part on the token number, to identify the acknowledged frame. In some aspects, the identifier field may be calculated as a combination of a token number and at least one of: one or more global addresses of the transmitter/receiver of the ACK, one or more local addresses of the transmitter/receiver of the ACK, one or more portions of the global address of the transmitter/receiver of the ACK, one or more portions of the local address of the transmitter/receiver of the ACK, or all or a portion of the CRC of the frame.

In some other aspects, the token number may be included in an ACK and/or another field of the acknowledged frame, such as a SIG field and/or a Control information (Control Info) field. In some aspects, the token may be derived from a scrambling seed in a service field of the acknowledged frame, which may follow the PHY preamble.

In some aspects, the rate control indication field of the ACK may include one or more bits that indicate that the receiver of the frame (the transmitter of the ACK) suggests an MCS that the transmitter of the frame should use. For example, in one aspect, the value of the one or more bits may indicate whether the MCS should be lowered, raised, or remain the same, and may indicate how much the MCS should be changed. In another aspect, the value of one or more bits may indicate a particular MCS. The frame may further include a number of spatial streams indication indicating a number of spatial streams used to transmit the frame.

In some aspects, the indication of buffered data is used to indicate that the transmitter of the ACK has data buffered and ready to send to the receiver of the ACK. For example, the STA106a may poll the AP104 (such as through PS-poll messages) to determine whether the AP104 has data buffered to send to the STA106 a. The AP104 may thus respond with an ACK acknowledging successful receipt of the poll, the ACK having a buffered data indication field, and wherein the value of the field indicates whether the AP104 has buffered data.

Fig. 6 is a table illustrating fields that may be included in a SIG field of an example of an ACK frame. In the illustrated aspect, the SIG field includes or includes only a 1-bit control field 605, a 3-bit type field 610, a 13-bit address/identifier field 615 for AID or 32-bit for FCS or 40-bit for partial MAC address, a 1-4-bit rate adaptation information field 620, a 4-bit CRC field 625, and a 6-bit tail field 630. The control field 605 indicates whether the frame is a control frame, as described above. The type field 610 defines the type of frame, as described above. The address/identifier field 615 corresponds to one of an address field or an identifier field, as described above. Rate adaptation information field 620 corresponds to the rate control indication field, as described above. The CRC field 625 corresponds to the CRC of the ACK frame. The tail field 630 corresponds to information required by the PHY layer to decode the ACK frame.

Fig. 7 is a table illustrating fields that may be included in a SIG field of another example of an ACK frame. In the illustrated aspect, the SIG field includes or only includes a length field 705 of 12 or 9 bits, optionally (depending on whether the length field indicates type, as discussed above) a type field 710, an address/identifier field 715 of 13 bits for AID or 32 bits for FCS or 40 bits for a partial MAC address, a CRC field 725 of 4 bits, and a tail field 730 of 6 bits. The length field 705 corresponds to the length field described above. The type field 710 defines the type of frame, as described above. The address/identifier field 715 corresponds to one of an address field or an identifier field, as described above. The CRC field 725 corresponds to the CRC of the ACK frame. The tail field 730 corresponds to information required by the PHY layer to decode the ACK frame.

Fig. 8 illustrates another example of an ACK frame having a similar format as the control frame of fig. 5. As shown, the ACK frame 800 includes an STF field 805, and LTF field 810, SIG field 815, service field 820, FC field 825, and FCs field 830. In this embodiment, the control information may not be included in the ACK frame. Specifically, the FCS field 830 may be modified to indicate that the frame is an ACK frame. Specifically, FCS field 830, instead of including the CRC of ACK frame 800, may include a copy of the FCS of the frame being acknowledged. If the receiving side of the ACK frame 800 transmits a frame with the same FCS, it may be determined that the frame is the ACK frame 800. In some aspects, the transmitter of the frame may expect an ACK frame 800 within a particular time interval, and thus may check whether an incoming packet has a duplicate FCS only for that time interval. Further, in some aspects, the FC field 825 may include an indicator that indicates whether the frame is an ACK.

Fig. 14 illustrates another example of an ACK frame 1400 according to the teachings herein. As shown, the ACK frame 1400 includes a 4-bit MCS (which indicates the type of control frame), a 14-bit ACK ID (which may include a partial FCS and a scrambler seed), a 5-bit duration, 3 or 15 bits of other fields, a 4-bit cyclic redundancy check, and a 6-bit tail.

In some aspects, a method of wireless communication includes generating an acknowledgement frame including control information substantially comprising: one or more of a length field, a cyclic redundancy check field, and a transmit power indication field; and one or more of an address field, an identifier field, a rate control indication field, and a buffered data indication field. The method further includes transmitting the acknowledgement frame. In some aspects, the address field includes one of a global address or a local address. In some aspects, the address field includes one of an address of a transmitter of the acknowledgment frame or a receiver of the acknowledgment frame.

In some aspects, the identifier field includes one of a hash of the acknowledged packet, a cyclic redundancy check of the acknowledged packet, a token, or a sequence number of the acknowledged packet.

In some aspects, the rate control indication field indicates an amount to change the modulation coding scheme. In some aspects, the rate control indication field indicates a modulation coding scheme.

In some aspects, the acknowledged frame includes information based at least on a frame check sequence of the acknowledged packet. In some aspects, the information based at least on the frame check sequence includes an identifier based on the frame check sequence and one or more of: a scrambling seed from a service field of the acknowledged packet and a sequence number from the acknowledged packet. In some aspects, the information is based on a type of the packet being acknowledged.

In some aspects, one type of control frame is PS-poll. For example, the STA106a may send a PS-poll to the AP104 to determine whether the AP104 has data to send to the STA106 a. In one aspect, the control information for PS-poll may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: a global address of a receiver of the PS-poll, a local address of a sender of the PS-poll, an information field, and a field indicating a token number. As discussed above, the token number may be generated by the transmitter of the PS-poll (e.g., according to an algorithm) and may have a different value for each PS-poll sent by the transmitter. The control information of the PS-poll may not include any additional field. The information field may include the latest beacon version that the sender of the PS-poll has received, so the receiver of the PS-poll may compare the sender's version to the actual version. In another aspect, the information fields may include one or more of the following in any combination: one or more global addresses of the transmitter/receiver of the PS-poll, one or more local addresses of the transmitter/receiver of the PS-poll, one or more portions of the global address of the transmitter/receiver of the PS-poll, one or more portions of the local address of the transmitter/receiver of the PS-poll, or a scrambler seed (or a portion of a scrambling seed) of a beacon carrying a Traffic Indication Map (TIM) for which the PS-poll is sent. For example, the information field may include the BSSID of the AP and the AID of the STA in any order. If there is a mismatch between the sender's version and the actual version, the receiver of the PS-poll may send new information to the sender of the PS-poll.

In some aspects, the control information for PS-poll may include an identifier. The identifier value may be set to the same value or a value derived therefrom as the beacon (e.g., the most recently received beacon) received by the STA106a from the AP104 or a corresponding identifier (e.g., a scrambler seed) included in other paging frames. When an identifier is present, the receiver address of the PS-poll may be omitted from the frame, since the identifier identifies the intended receiver. Further, the PS-poll may include a portion of its AID (e.g., 11 LSBs of its AID) in the PS-poll identifier. Furthermore, the sender of a beacon or paging message may change the identifier of any given beacon, thereby providing diversity across time.

Fig. 13 illustrates an example of a PS-poll control frame 1300, which includes a 4-bit MCS (which indicates the type of control frame), a 7-bit receiver address, an 11-bit transmitter address, 4 or 16-bit other fields, a 4-bit cyclic redundancy check, and a 6-bit trailer.

In some aspects, PS-poll frames may be used in conjunction with ACK frames as described below. A STA may send a PS-poll intended for the AP with which the STA is associated. Upon receiving the PS-poll, the AP may respond with an ACK frame, such as those described herein. For example, the ACK frame may include an identifier calculated based on the token number included in the PS-poll frame as described above. The token may be a PS-poll identifier. The use of the token number in the response advantageously allows the identifier of the ACK to be different for each PS-poll, thereby allowing the device to easily distinguish between multiple ACKs if the device receives multiple ACKs at the same time. In another example, the ACK frame may include one or more of the following in any combination: one or more global addresses of the transmitter/receiver of the PS-poll, one or more local addresses of the transmitter/receiver of the PS-poll, one or more parts of the global address of the transmitter/receiver of the PS-poll or one or more parts of the local address of the transmitter/receiver of the PS-poll (which may be copied from the PS-poll).

In some aspects, a method of wireless communication includes generating a power save poll frame including control information substantially including: one or more of a length field, a cyclic redundancy check field, and a transmit power indication field; and one or more of a destination address field, a transmitter address field, and an information field. The method further includes transmitting the power save poll frame. In some aspects, the information field includes a beacon version. In some aspects, the destination address field includes a global address and the transmitter address field includes a local address. In some aspects, the information field includes an identifier based on the received beacon.

In some aspects, one type of control frame is RTS. In one aspect, the control information of the RTS may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: a global address of a receiver of the RTS, a local address of a sender of the RTS, and a duration field. The control information of the RTS may not include any additional fields. In some aspects, the RTS may additionally or alternatively include a transmit power indication (along with one or more fields described above as being included in all types of control frames), which may be expressed in dB or in rank (e.g., 2 bits may indicate 4 ranks of transmit power). Further, the RTS may additionally or alternatively include a bandwidth indication (along with one or more fields described above as being included in all types of control frames). In one aspect, the bandwidth indication may be present only for 2MHz (or greater) control frames. The duration field may indicate a duration for which the RTS reserves the communication channel. In one aspect, the duration field may indicate the duration in 2 bytes (or less) and represent the duration in μ s. In another aspect, the duration may indicate the duration with other time intervals (e.g., number of symbols, multiple of 40 μ β, number of slots, etc.). As an example, the duration field may indicate up to 20.5ms, with a duration field length of 9 bits and expressed as a multiple of 40 μ β. In some aspects, the length of the time interval is declared by the AP104 and transmitted in another message (such as a beacon) or during association with the STA106 a.

In some aspects, a method of wireless communication includes generating a request-to-send frame including control information substantially comprising: one or more of a length field, a cyclic redundancy check field, and a transmit power indication field; and one or more of a destination address field, a transmitter address field, and a duration field. The method further includes transmitting the request-to-send frame. In some aspects, the destination address field includes a global address and the transmitter address field includes a local address. In some aspects, the duration field expresses the duration in multiples of a symbol.

Fig. 15 illustrates an example of an RTS control frame 1500 that includes a 4-bit MCS (which indicates the type of control frame), a 13-bit RTS ID (e.g., receiver AID), a 9-bit duration field, other fields, a 4-bit cyclic redundancy check, and a 6-bit tail. The RTS1500 may additionally include a bandwidth indication of 2 bits and/or may additionally include a transmit power level of 2 bits.

In some aspects, one type of control frame is a CTS. In one aspect, the control information of the CTS may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: the local address and duration field of the sender of the RTS for which the CTS is being sent. The local address and duration fields may be copied (or derived) from the RTS for which the CTS is being sent. Alternatively, the CTS may not include an address copied from the RTS and instead may include an identifier defined in a manner similar to the ACK frame discussed above. The control information of the CTS may not include any additional field. Alternatively, the CTS may include additional fields previously described for RTS frames.

Fig. 16 illustrates an example of a CTS control frame 1600 that includes a 4-bit MCS (which indicates the type of control frame), a 7-bit CTS ID (e.g., a copy (or portion) of the partial FCS and scrambler seed information from the RTS and/or a partial transmitter address and/or RTS ID of the transmitter if the CTS is transmitted to itself), a 9-bit duration field, other fields of 6 or 18 bits, a 4-bit cyclic redundancy check, and a 6-bit tail. The CTS1600 may additionally include a bandwidth indication of 2 or 3 bits and/or may additionally include a transmit power level of 2 bits.

In some aspects, the CTS control frame 1600 may further include an MCS field including one or more bits indicating a suggested MCS for data transmission, which may be used, for example, to enable fast link adaptation. For example, upon receiving an RTS frame from a second STA, the first STA may transmit a CTS control frame 1600 and indicate to the second STA, using the MCS field of the frame 1600, a suggested MCS that the second STA may use for subsequent data transmissions to the first STA. The second STA may choose the MCS indicated in the MCS field to select an MCS for the subsequent data transmission.

In some aspects, the MCS field may indicate the MCS index according to an MCS definition in the IEEE standard. In some aspects, the MCS field may include a relative MCS, including an indication to increase or decrease the MCS for a given reference MCS. For example, the reference MCS may be an MCS used to solicit transmission of an RTS. As another example, the reference MCS may be an MCS explicitly indicated in a field of the solicited RTS. As another example, the reference MCS may be an MCS for the last successful data transmission. In some aspects, the CTS may further include an indication that the sender of the CTS has buffered data units or frames ready for delivery to the recipient of the CTS.

In some aspects, the MCS field of the CTS control frame 1600 may include two bits to indicate a suggested MCS. For example, the following bit combinations may be used to indicate a suggested MCS:

MCS identical to RTS

-01: MCS ' +1 ' of RTS '

-10: MCS ' +2 ' of RTS '

-11: MCS ' +3 ' of RTS '

As another example, if the RTS frame is sent at MCS2rep 2:

-00:MCS0rep2

-01:MCS0

-10:MCS1

-11:MCS2

in some aspects, the CTS control frame 1600 may include a 1-bit to indicate that the CTS is a response to an RTS but that it does not grant a transmission opportunity (TXOP) to the STA. For example, the CTS control frame 1600 may indicate that the RTS was received, but the Network Allocation Vector (NAV) is not set and the transmitter of the RTS is not granted the possibility to send data after the CTS. In some aspects, the duration field of the CTS control frame 1600 is not used to indicate a NAV duration if the CTS control frame 1600 indicates that it is not granted TXOP. In such aspects, the duration field may be used to indicate a time after which the STA is allowed to send another RTS frame or data.

In some aspects, a method of wireless communication includes generating a clear to send frame including control information substantially comprising: one or more of a length field, a cyclic redundancy check field, and a transmit power indication field; and one or more of a destination address field and a duration field. The method further includes transmitting the clear to send frame. In some aspects, the clear to send control frame includes a physical layer preamble having a signal field that includes control information.

In some aspects, one type of control frame is a BAR. For example, STA106a may send a BAR to another STA to request that the other STA send a BA. In one aspect, the control information of a BAR may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: a global address, a local address, an address interpretation field, a Traffic Identifier (TID) field, and a starting sequence number field. The control information of the BAR may not include any additional field. The global address may be a global address of a transmitter of the BAR or a receiver of the BAR. The local address may be a local address of the other of the transmitter of the BAR and the receiver of the BAR whose global address is not included in the BAR. The address interpretation field may be 1 or 2 bits indicating whether the global address is the address of the transmitter and the local address is the address of the receiver, or whether the global address is the address of the receiver and the local address is the address of the transmitter. Since BA is defined per TID and requires a sequence number of the starting block for which BA is requested, these values are included in the BAR. The TID may be 3 bits and the starting sequence number may be 12 bits. In some aspects, the starting sequence number may be a partial sequence number, such as one or more of the least or most significant bits of the starting sequence number. The length of the partial sequence number may depend on the maximum number of MPDUs that the block ACK frame can acknowledge. As an example, a partial sequence number of 6 bits in length is sufficient to distinguish multiple blocks of 64 MPDUs. In some aspects, the TID identifies the access category, and each access category identifies 2 sub-categories for a total of 8 sub-categories. In other aspects, an indication of the access category is sufficient. In some aspects, instead of a 3-bit TID, the control field may include a 2-bit access category.

In another aspect, the control information of the BAR may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: a global address, a first local address, a second local address, a Traffic Identifier (TID) field, and a starting sequence number field. The control information of the BAR may not include any additional field. The global address may indicate BSSIDs of the transmitter and the receiver. The first and second local addresses may be local addresses of the transmitter and the receiver.

In another aspect, the control information of the BAR may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: a first global address, a second global address, a Traffic Identifier (TID) field, and a starting sequence number field. The control information of the BAR may not include any additional field. The first and second global addresses may be global addresses of the transmitter and the receiver.

In some aspects, a method of wireless communication includes generating a block acknowledgement request frame including control information substantially comprising: one or more of a length field, a cyclic redundancy check field, and a transmit power indication field; and one or more of a global address field, a local address field, an address interpretation field, a traffic identifier field, and a starting sequence number field. The method further includes transmitting the block acknowledgement request frame.

In some aspects, one type of control frame is a BA. For example, the STA106a may send a BA to acknowledge receipt of multiple frames. In one aspect, the control information of the BA may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: a global address, a local address, an address interpretation field, a Traffic Identifier (TID) field, a starting sequence number field, and a bitmap. The control information of the BA may not include any additional field. The global address may be a global address of a transmitter of the BA or a receiver of the BA. The local address may be a local address of the other of the transmitter of the BA and the receiver of the BA whose global address is not included in the BA. The address interpretation field may be 1 or 2 bits indicating whether the global address is the address of the transmitter and the local address is the address of the receiver, or whether the global address is the address of the receiver and the local address is the address of the transmitter. These values are included in the BA because the BA is defined per TID and requires a sequence number of the starting block for which the BA is requested. The TID may be 3 bits and the starting sequence number may be 12 bits. Further, the bitmap may be, for example, 4, 8, 16, 32, or 64 bits. The value of the bitmap may indicate which frames were successfully received and which were not. In some aspects, any of the TID, sequence number, and receiver address may be excluded from the BA because the transmitter of the BAR may expect a BA from a particular responder within a particular time interval. Thus, if a BA with the address of the transmitter is received in this time interval, the transmitter may assume the TID and starting sequence number sent in the BAR.

In another aspect, the control information of the BA may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: a global address, a first local address, a second local address, a Traffic Identifier (TID) field, a starting sequence number field, and a bitmap. The control information of the BA may not include any additional field. The global address may indicate BSSIDs of the transmitter and the receiver. The first and second local addresses may be local addresses of the transmitter and the receiver.

In another aspect, the control information of the BA may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: a first global address, a second global address, a Traffic Identifier (TID) field, a starting sequence number field, and a bitmap. The control information of the BA may not include any additional field. The first and second global addresses may be global addresses of the transmitter and the receiver.

In another aspect, the control information of the BA may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: a bitmap and a BA identifier. The control information of the BA may not include any additional field. The bitmap may be a 2, 4, 8, 16, 32 bitmap indicating whether the corresponding packet was received correctly or not. A bit in position n of the bitmap may refer to a packet with a sequence number equal to n plus the sequence number indicated in the BAR frame immediately preceding the BA. In some aspects, the TID or AC value is also assumed to be one TID or AC value from the immediately preceding BAR. The identifier may be defined in the same or similar manner as defined for the ACK identifier.

Fig. 17 illustrates an example of a BA frame 1700 in accordance with the teachings herein. As shown, BA frame 1700 includes a 4-bit MCS (which indicates the type of control frame), a 7-bit block ACK ID (e.g., scrambler seed from the first MPDU or BAR), a 5-bit Starting Sequence Number (SSN) (e.g., SSN of the first MPDU acknowledged or 5 LSBs of SSN of the first MPDU acknowledged), an 8-bit or 16-bit map, other fields, a 4-bit cyclic redundancy check, and a 6-bit trailer. In some aspects, BA frame 1700 may include a 1-bit ACK mode field indicating whether the BA is used for block or segment acknowledgements. In some aspects, BA frame 1700 may include a 1-bit doppler indication field.

In some aspects, a method of wireless communication includes generating a block acknowledgement frame including control information substantially comprising: one or more of a length field, a cyclic redundancy check field, and a transmit power indication field; and one or more of a global address field, a local address field, an address interpretation field, a traffic identifier field, a starting sequence number field, and a bitmap. The method further includes transmitting the block acknowledgement frame.

In some aspects, one type of control frame is a CF-end. CF-ending may be used to cancel reservations made in response to a Network Allocation Vector (NAV). In one aspect, the control information of the CF-end may include or substantially include a type field. The control information of the CF-end may not include any additional field. Any receiver that receives the type field indicating CF-end may then determine that any NAV should be cancelled. In another aspect, the control information for CF-end may include or substantially include a type field and one or more other fields described above as being included in all types of control frames. The control information of the CF-end may not include any additional field.

In some aspects, a method of wireless communication includes generating a contention-free end frame including control information substantially including a type field. The method further includes transmitting the contention-free end frame.

In some aspects, one type of control frame is a CF-end poll. The CF-end poll itself may be used to cancel a reservation made in response to a Network Allocation Vector (NAV) in the transmission range of the transmitter of the CF-end poll and further request that the receiver of the CF-end poll transmit a CF-end to cancel the reservation in the transmission range of the receiver of the CF-end poll. In one aspect, the control information for a CF-end poll may include a global address of the receiver of the CF-end poll and one or more of the type fields described above as being included in all types of control frames. In another aspect, the control information for a CF-end poll may include or substantially include the global address of the receiver of the CF-end poll and one or more of the type fields described above as being included in all types of control frames. In another aspect, the control information for a CF-end poll may include or substantially include a global address of a receiver of the CF-end poll and a type field indicating that the frame is a CF-end poll.

In some aspects, a method of wireless communication includes generating a contention-free end poll frame including control information substantially comprising: one or more of a length field, a cyclic redundancy check field, and a transmit power indication field; and a receiver global address field. The method further includes transmitting a contention-free end poll frame.

In some aspects, one type of control frame is an MCS request. For example, the AP104 may send an MCS request to the STA106a to request information from the STA106a regarding which MCS to use for transmission. In one aspect, the control information of the MCS request may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: a global address of a receiver of the MCS request and a local address of a sender of the MCS request. The control information of the MCS request may not include any additional fields.

In some aspects, a method of wireless communication includes generating a modulation coding scheme request frame including control information substantially comprising: one or more of a length field, a cyclic redundancy check field, and a transmit power indication field; and one or more of a receiver global address field and a transmitter local address field. The method further includes transmitting the modulation coding scheme request frame.

In some aspects, one type of control frame is an MCS response. For example, the AP104 may send an MCS request to the STA106a to request information from the STA106a regarding which MCS to use for transmission. In return, the STA106a may send such information in an MCS response. In one aspect, the control information of the MCS response may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: the local address of the sender of the MCS request for which the MCS response is sent (copied from the MCS request), the MCS field (e.g., 4 bits), and additional information (e.g., signal-to-noise ratio (SNR)). The control information of the MCS response may not include any additional fields.

In some aspects, a method of wireless communication includes generating a modulation coding scheme response frame including control information substantially comprising: one or more of a length field, a cyclic redundancy check field, and a transmit power indication field; and one or more of a receiver local address field, a modulation coding scheme field, and an information field. The method further includes transmitting the modulation coding scheme response frame.

In some aspects, one type of control frame is an NDP. For example, the AP104 may send an NDP to the STA106a to allow the STA106a to perform channel estimation using the NDP. In one aspect, the control information of the NDP may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: the number of spatial streams used for channel estimation and the channel bandwidth over which the estimation is made. The control information of the NDP may not include any additional fields.

In some aspects, a method of wireless communication includes generating a null data packet frame including control information substantially comprising: one or more of a length field, a cyclic redundancy check field, and a transmit power indication field; and one or more of a number of spatial streams field and a channel bandwidth field. The method further includes transmitting the null data packet frame.

In some aspects, one type of control frame is a probe request. For example, the STA106a seeking an AP may send a probe request to which the AP104 responds. In one aspect, the control information of the probe request may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: a global address of a transmitter of the probe request and a Service Set Identifier (SSID) field. The control information of the probe request may not include any additional fields. The SSID field may include the SSID or a hash of the SSID that STA106a is looking for. The hash of the SSID may be, for example, 4 bytes representing a portion of a full SSID or a CRC calculated based on a full CRC. Further, any AP that may not include the SSID field and therefore receives the probe request may respond.

In some aspects, a method of wireless communication includes generating a probe request frame including control information substantially comprising: one or more of a length field, a cyclic redundancy check field, and a transmit power indication field; and one or more of a transmitter global address field and a receiver service set identifier field. The method further includes transmitting the probe request frame.

In some aspects, one type of control frame is a probe response. For example, the STA106a seeking an AP may send a probe request to which the AP104 responds with a probe response. In one aspect, the control information of the probe response may include or substantially include one or more fields described above as being included in all types of control frames and one or more of the following fields: a global address of a transmitter of the probe response, a global address of a receiver of the probe response, and a Service Set Identifier (SSID) field. The control information of the probe response may not include any additional fields. The SSID field may include the SSID of the AP sending the probe response or a hash of the SSID. Further, the SSID field may not be included, for example, if the probe request includes an SSID, because the transmitter of the probe request may expect a probe response within a particular time interval. Thus, if a probe response with the address of the transmitter of the probe request is received in this time interval, the transmitter may assume the SSID sent in the probe request.

In some aspects, a method of wireless communication includes generating a probe response frame including control information substantially comprising: one or more of a length field, a cyclic redundancy check field, and a transmit power indication field; and one or more of a transmitter global address field, a receiver global address field, and a transmitter service set identifier field. The method further includes transmitting the probe response frame.

Fig. 9 illustrates a flow diagram of an aspect of an exemplary method 900 for generating and transmitting control frames. The method 900 may be used to generate and transmit any of the control frames described above. A control frame may be generated from one wireless device 202 or transmitted to another wireless device. Although the method 900 is described below with respect to elements of the wireless device 202 (fig. 2), one of ordinary skill in the art will appreciate that other components may be used to implement one or more of the steps described herein. Although the blocks may be described as occurring in a particular order, the blocks may be reordered, blocks may be omitted, and/or additional blocks may be added.

First, at block 902, the processor 204 and/or the DSP220 generates a control frame based on the content of the control frame. Subsequently, at block 904, the transmitter 210 transmits the control frame.

Fig. 10 is a functional block diagram of an exemplary wireless device 1000 that may be employed within the wireless communication system 100. The device 1000 includes a generating module 1002 for generating a control frame for wireless transmission. The generation module 1002 may be configured to perform one or more of the functions discussed above with respect to block 902 illustrated in fig. 9. The generating module 1002 may correspond to one or more of the processor 204 and the DSP 220. The device 1000 further comprises a transmitting module 1004 for wirelessly transmitting the data unit. The transmitting module 1004 may be configured to perform one or more of the functions discussed above with respect to block 904 illustrated in fig. 9. The transmitting module 1004 may correspond to the transmitter 210.

Fig. 11 illustrates a flow diagram of an aspect of an exemplary method 1100 for receiving and processing control frames. The method 1100 may be used to receive and process any of the control frames described above. The control frame may be received and processed at any wireless device 202. Although the method 1100 is described below with respect to elements of the wireless device 202 (fig. 2), one of ordinary skill in the art will appreciate that other components may be used to implement one or more of the steps described herein. Although the blocks may be described as occurring in a particular order, the blocks may be reordered, blocks may be omitted, and/or additional blocks may be added.

First, at block 1102, the receiver 212 receives a control frame. Subsequently, at block 1104, the processor 204 and/or the DSP220 processes the control frame based on the content of the control frame.

Fig. 12 is a functional block diagram of an exemplary wireless device 1200 that may be employed within the wireless communication system 100. The device 1200 comprises a receiving module 1002 for receiving a control frame. The receiving module 1202 may be configured to perform one or more of the functions discussed above with respect to block 1102 illustrated in fig. 11. The receiving module 1202 may correspond to the receiver 212. The device 1200 further comprises a processing module 1204 for processing the control frame. The transmitting module 1204 may be configured to perform one or more of the functions discussed above with respect to block 1104 illustrated in fig. 11. The processing module 1204 may correspond to one or more of the processor 204 and the DSP 220.

As used herein, the term "determining" encompasses a wide variety of actions. For example, "determining" can include calculating, computing, processing, deriving, studying, looking up (e.g., looking up in a table, database, or other data structure), ascertaining, and the like. Also, "determining" may include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory), and the like. Also, "determining" may include resolving, selecting, choosing, establishing, and the like. In addition, "channel width" as used herein may encompass or may also be referred to in some aspects as bandwidth.

As used herein, a phrase referring to "at least one of a list of items refers to any combination of those items, including a single member. By way of example, "at least one of a, b, or c" is intended to encompass: a. b, c, a-b, a-c, b-c and a-b-c.

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 modules. In general, any of the operations illustrated in the figures may be performed by corresponding functional means capable of performing the operations.

The various illustrative logical blocks, modules, and circuits described in connection with the disclosure may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a field programmable gate array signal (FPGA) or other Programmable Logic Device (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 in the alternative, 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, e.g., 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.

In one or more aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a web 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, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk (disk) and disc (disc), as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks (disks) usually reproduce data magnetically, while discs (discs) reproduce data optically with lasers. Thus, in some aspects, computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media). Additionally, in some aspects, the computer readable medium may comprise a transitory computer readable medium (e.g., a signal). Combinations of the above should also be included within the scope of computer-readable media.

The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another 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.

The functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions on a computer-readable medium. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk (disk) and disc (disc), as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk, and Blu-ray discDisks, where a disk (disk) usually reproduces data magnetically, and a disk (disc) reproduces data optically with a laser.

Accordingly, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having instructions stored (and/or encoded) thereon, 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 materials.

The software or instructions may also be transmitted over a transmission medium. For example, if the software is transmitted from a web 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, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of transmission medium.

Further, it is to be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station where applicable. For example, such a device can be coupled to a server to facilitate the transfer of an apparatus for performing the methods described herein. Alternatively, the various methods described herein can be provided via a storage device (e.g., RAM, ROM, a physical storage medium such as a Compact Disc (CD) or floppy disk, etc.) such that, upon coupling or providing the storage device to a user terminal and/or base station, the apparatus can obtain the various methods. Further, any other suitable technique suitable for providing the methods and techniques described herein to a device can be utilized.

It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various changes, substitutions and alterations in the arrangement, operation and details of the method and apparatus described above may be made without departing from the scope of the claims.

While the foregoing is directed to aspects of the present disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims (72)

1. A method of wireless communication, comprising:

generating a frame comprising a physical layer preamble having a signal field, the signal field comprising:

an indicator indicating that the signal field is encoded with a plurality of fields including information associated with a frame type; and

a cyclic redundancy check field;

encoding the plurality of fields including information associated with the frame type in the signal field of the frame, the information including:

type information indicating the frame type; and

additional information determined based on the type of frame,

wherein the frame type is at least one of a group of frame types, the group comprising: an acknowledgement frame; a power save poll frame; clearing the sending frame; and a block acknowledgement frame; and

the frame is transmitted.

2. The method of claim 1, wherein the indicator comprises a length field indicating that the frame is encoded with a plurality of fields comprising information associated with the frame type.

3. The method of claim 2, wherein a value of 0 for the length field indicates that the frame is encoded with a plurality of fields that include information associated with the frame type.

4. The method of claim 2, wherein a value of the length field less than 10 indicates that the frame is encoded with a plurality of fields including information associated with the frame type.

5. The method of claim 4, wherein the value indicates the frame type.

6. The method of claim 1, wherein the additional information comprises control information associated with the frame type.

7. The method of claim 6, wherein the control information comprises a transmit power indication field.

8. The method of claim 6, wherein the control information comprises an indicator of a bandwidth of the frame.

9. The method of claim 1, wherein the frame substantially comprises a physical layer preamble.

10. The method of claim 1, wherein the indicator comprises a single bit.

11. The method of claim 1, wherein the indicator comprises a reserved value for a field of the frame.

12. The method of claim 1, wherein the frame further comprises a control extension field comprising control information associated with the frame type.

13. The method of claim 12, wherein the control extension field has a predefined modulation coding scheme.

14. The method of claim 1, wherein the frame type is a request to send frame.

15. The method of claim 1, wherein the frame type is a block acknowledgement request frame.

16. The method of claim 1, wherein the frame type is at least one of a contention-free end frame and a contention-free end poll frame.

17. The method of claim 1, wherein the frame type is at least one of a modulation coding scheme request frame and a modulation coding scheme response frame.

18. The method of claim 1, wherein the frame type is at least one of a probe request frame and a probe response frame.

19. A wireless device, comprising:

a processor configured to:

generating a frame comprising a physical layer preamble having a signal field, the signal field comprising:

an indicator indicating that the signal field is encoded with a plurality of fields including information associated with a frame type; and

a cyclic redundancy check field;

encoding the plurality of fields including information associated with the frame type in the signal field of the frame, the information including:

type information indicating the frame type; and

additional information determined based on the type of frame,

wherein the frame type is at least one of a group of frame types, the group comprising: an acknowledgement frame; a power save poll frame; clearing the sending frame; and a block acknowledgement frame; and

a transmitter configured to transmit the frame.

20. The wireless device of claim 19, wherein the indicator comprises a length field indicating that the frame is encoded with a plurality of fields comprising information associated with the frame type.

21. The wireless device of claim 20, wherein a value of 0 for the length field indicates that the frame is encoded with a plurality of fields including information associated with the frame type.

22. The wireless device of claim 20, wherein a value of the length field less than 10 indicates that the frame is encoded with a plurality of fields including information associated with the frame type.

23. The wireless device of claim 22, wherein the value indicates a frame type.

24. The wireless device of claim 19, wherein the additional information comprises control information associated with the frame type.

25. The wireless device of claim 24, wherein the control information comprises a transmit power indication field.

26. The wireless device of claim 24, wherein the control information comprises an indicator of a bandwidth of the frame.

27. The wireless device of claim 19, wherein the frame substantially comprises a physical layer preamble.

28. The wireless device of claim 19, wherein the indicator comprises a single bit.

29. The wireless device of claim 19, wherein the indicator comprises a reserved value for a field of the frame.

30. The wireless device of claim 19, wherein the frame further comprises a control extension field comprising control information associated with the frame type.

31. The wireless device of claim 30, wherein the control extension field has a predefined modulation coding scheme.

32. The wireless device of claim 19, wherein the frame type is a request to send frame.

33. The wireless device of claim 19, wherein the frame type is a block acknowledgement request frame.

34. The wireless device of claim 19, wherein the frame type is at least one of a contention-free end frame and a contention-free end poll frame.

35. The wireless device of claim 19, wherein the frame type is at least one of a modulation coding scheme request frame and a modulation coding scheme response frame.

36. The wireless device of claim 19, wherein the frame type is at least one of a probe request frame and a probe response frame.

37. A wireless device, comprising:

means for generating a frame comprising a physical layer preamble having a signal field, the signal field comprising:

an indicator indicating that the signal field is encoded with a plurality of fields including information associated with a frame type; and

a cyclic redundancy check field; and

means for encoding the plurality of fields, the plurality of fields comprising information associated with the frame type in the signal field of the frame, the information comprising:

type information indicating the frame type; and

additional information determined based on the type of frame,

wherein the frame type is at least one of a group of frame types, the group comprising: an acknowledgement frame; a power save poll frame; clearing the sending frame; and a block acknowledgement frame; and

means for transmitting the frame.

38. The wireless device of claim 37, wherein the indicator comprises a length field indicating that the frame is encoded with a plurality of fields comprising information associated with the frame type.

39. The wireless device of claim 38, wherein a value of 0 for the length field indicates that the frame is encoded with a plurality of fields including information associated with the frame type.

40. The wireless device of claim 38, wherein a value of the length field less than 10 indicates that the frame is encoded with a plurality of fields including information associated with the frame type.

41. The wireless device of claim 40, wherein the value indicates the frame type.

42. The wireless device of claim 37, wherein the additional information comprises control information associated with the frame type.

43. The wireless device of claim 42, wherein the control information comprises a transmit power indication field.

44. The wireless device of claim 42, wherein the control information comprises an indicator of a bandwidth of the frame.

45. The wireless device of claim 37, wherein the frame substantially comprises a physical layer preamble.

46. The wireless device of claim 37, wherein the indicator comprises a single bit.

47. The wireless device of claim 37, wherein the indicator comprises a reserved value for a field of the frame.

48. The wireless device of claim 37, wherein the frame further comprises a control extension field comprising control information associated with the frame type.

49. The wireless device of claim 48, wherein the control extension field has a predefined modulation coding scheme.

50. The wireless device of claim 37, wherein the frame type is a request to send frame.

51. The wireless device of claim 37, wherein the frame type is a block acknowledgement request frame.

52. The wireless device of claim 37, wherein the frame type is at least one of a contention-free end frame and a contention-free end poll frame.

53. The wireless device of claim 37, wherein the frame type is at least one of a modulation coding scheme request frame and a modulation coding scheme response frame.

54. The wireless device of claim 37, wherein the frame type is at least one of a probe request frame and a probe response frame.

55. An apparatus for wireless communication, comprising:

circuitry for generating a frame comprising a physical layer preamble having a signal field, the signal field comprising:

an indicator indicating that the signal field is encoded with a plurality of fields including information associated with a frame type; and

a cyclic redundancy check field; and

circuitry for encoding the plurality of fields, the plurality of fields comprising information associated with the frame type in the signal field of the frame, the information comprising:

type information indicating the frame type; and

additional information determined based on the type of frame,

wherein the frame type is at least one of a group of frame types, the group comprising: an acknowledgement frame; a power save poll frame; clearing the sending frame; and a block acknowledgement frame; and

circuitry for transmitting the frame.

56. The apparatus of claim 55, wherein the indicator comprises a length field indicating that the frame is encoded with a plurality of fields comprising information associated with the frame type.

57. The apparatus of claim 56, wherein a value of 0 for the length field indicates that the frame is encoded with a plurality of fields comprising information associated with the frame type.

58. The apparatus of claim 56, wherein a value of the length field less than 10 indicates that the frame is encoded with a plurality of fields comprising information associated with the frame type.

59. The apparatus of claim 58, wherein the value indicates the frame type.

60. The apparatus of claim 55, wherein the additional information comprises control information associated with the frame type.

61. The apparatus of claim 60, wherein the control information comprises a transmit power indication field.

62. The apparatus of claim 60, wherein the control information comprises an indicator of a bandwidth of the frame.

63. The apparatus of claim 55, wherein the frame substantially comprises a physical layer preamble.

64. The apparatus of claim 55, wherein the indicator comprises a single bit.

65. The apparatus of claim 55, wherein the indicator comprises a reserved value for a field of the frame.

66. The apparatus of claim 55, wherein the frame further comprises a control extension field comprising control information associated with the frame type.

67. The apparatus of claim 66, wherein the control extension field has a predefined modulation coding scheme.

68. The apparatus of claim 55, wherein the frame type is a request to send frame.

69. The apparatus of claim 55, wherein the frame type is a block acknowledgement request frame.

70. The apparatus of claim 55, wherein the frame type is at least one of a contention-free end frame and a contention-free end poll frame.

71. The apparatus of claim 55, wherein the frame type is at least one of a modulation coding scheme request frame and a modulation coding scheme response frame.

72. The apparatus of claim 55, wherein the frame type is at least one of a probe request frame and a probe response frame.