WO2019066933A1

WO2019066933A1 - Methods, systems, and apparatus for reducing co-channel interference in full-duplex wi-fi

Info

Publication number: WO2019066933A1
Application number: PCT/US2017/054454
Authority: WO
Inventors: Alexander W. Min; Shahrnaz Azizi; Juan FANG; Shu-Ping Yeh; Laurent Cariou; Minyoung Park; Thomas Kenney
Original assignee: Intel Corporation
Priority date: 2017-09-29
Filing date: 2017-09-29
Publication date: 2019-04-04

Abstract

Methods and apparatus for reducing co-channel interference in full-duplex Wi-Fi are disclosed. An example apparatus includes a receiver to receive a pilot tone pattern corresponding to a reservation of a first pilot sub-carrier for at least one of uplink or downlink transmission; and an uplink/downlink converter to when the first pilot sub-carrier is reserved for uplink transmission during a full-duplex transmission, refrain from receiving a downlink packet; and when the first pilot sub-carrier is not reserved for uplink transmission, receiving a downlink packet.

Description

METHODS, SYSTEMS, AND APPARATUS FOR REDUCING CO-CHANNEL

INTERFERENCE IN FULL-DUPLEX WI-FI

FIELD OF THE DISCLOSURE

This disclosure relates generally to wireless fidelity connectivity (Wi-Fi) and, more particularly, to methods and apparatus for reducing co-channel interference in full-duplex Wi-Fi.

BACKGROUND

Many locations provide Wi-Fi to connect Wi-Fi enabled devices to networks such as the Internet. Wi-Fi enabled devices include personal computers, video-game consoles, mobile phones and devices, digital cameras, tablets, smart televisions, digital audio players, etc. Wi-Fi allows the Wi-Fi enabled devices to wirelessly access the Internet via a wireless local area network (WLAN). To provide Wi-Fi connectivity to a device, a Wi-Fi access point transmits a radio frequency Wi-Fi signal to the Wi-Fi enabled device within the access point (e.g., a hotspot) signal range. Wi-Fi is implemented using a set of media access control (MAC) and physical layer (PHY) specifications (e.g., such as the Institute of Electrical and Electronics Engineers (IEEE) 802.11 protocol).

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration of communications using wireless local area network Wi-Fi protocols to reduce co-channel interference.

FIG. 2 is a block diagram of an example access point communication converter of FIG. 1. FIG. 3 is a block diagram of an example station communication converter of FIG. 1. FIG. 4 is a flowchart representative of example machine readable instructions that may be executed to implement the example access point communication converter of FIG. 1.

FIGS. 5-7 is a flowchart representative of example machine readable instructions that may be executed to implement the example station communication converter of FIG. 1.

FIG. 8 is an example PHY layer that may be utilized by an example access point and an example station of FIG. 1 to determine if a pilot tone algorithm is enabled.

FIG. 9 is an example trigger frame that may be utilized by the example access point to identify a pilot tone pattern. FIGS. 10-14 are example pilot tone patterns that may be utilized by the example access point and the example stations of FIG. 1 to reduce and/or measure co-channel interference.

FIG. 15 is a block diagram of a processor platform structured to execute the example machine readable instructions of FIG. 4 to implement the example access point communication converter of FIG. 2.

FIG. 16 is a block diagram of a processor platform structured to execute the example machine readable instructions of FIGS. 5-7 to implement the example station communication converter of FIG. 3.

The figures are not to scale. Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts.

DETAILED DESCRIPTION

Various locations (e.g., homes, offices, coffee shops, restaurants, parks, airports, etc.) may provide Wi-Fi to the Wi-Fi enabled devices (e.g., stations (STA)) to connect the Wi-Fi enabled devices to the Internet, or any other network, with minimal hassle. The locations may provide one or more Wi-Fi access points (APs) to output Wi-Fi signals to the Wi-Fi enabled device within a range of the Wi-Fi signals (e.g., a hotspot). A Wi-Fi AP is structured to wirelessly connect a Wi-Fi enabled device to the Internet through a wireless local area network (WLAN) using Wi-Fi protocols (e.g., such as IEEE 802.11). The Wi-Fi protocol is the protocol for how the AP communicates with the devices to provide access to the Internet by transmitting uplink (UL) transmissions and receiving downlink (DL) transmissions to/from the Internet.

In some examples, an AP communicates with one or more STAs using a full-duplex Wi- Fi communication protocol. A full-duplex Wi-Fi protocol facilitates both UL and DL

transmissions between an AP and two or more STAs at the same time. In a full-duplex Wi-Fi communication protocol, the AP and an uplink (UL) STA (e.g., a station transmitting UL packets to the AP) transmit data packets on the same channel (e.g., an orthogonal frequency-division multiplexing (OFDM) pilot sub-carrier at a particular index) for downlink (DL) and UL transmissions, respectively. However, in-band (e.g., same channel) full-duplex UL and DL transmissions make it difficult for a DL STA (e.g., a STA receiving DL packets from the AP) to perform pilot-based phase tracking for DL data symbols (e.g., DL data packets) due to co- channel interference (e.g., pilot contamination) caused by UL pilot signals (e.g., UL data packets) that overlap with DL pilot signals in time and/or frequency. Co-channel interference may exist on pilot tones and/or data tones. To adjust full-duplex transmissions to reduce co- channel interference on the data tones for subsequent transmissions, some traditional techniques instruct the DL STA to measure the co-channel interference using additional overhead which may limit the full-duplex gain. For example, to schedule full-duplex UL and DL transmissions, a traditional AP may schedule interference measurement periods, during which the connected STAs measure interference levels from each other and report the measurements to the AP. In such an example, the AP uses the interference report to adjust subsequent full-duplex UL and DL communications to reduce the co-channel interference. However, such traditional techniques are done at the cost of additional overhead. Additionally, the frequent scheduling of interference measurement periods limits the full-duplex gain. Additionally, traditional techniques do not reduce co-channel interference on the pilot tones.

Examples disclosed herein facilitate a pilot tone pattern for full duplex Wi-Fi protocols to decrease and/or measure co-channel interference or other pilot contaminations on the data tones and the pilot tones. A pilot tone pattern is a pattern that reserves pilot sub-carriers (e.g., OFDM sub-carriers) for UL transmissions and DL transmissions during a full-duplex transmission that avoids overlap (e.g., the same sub-carrier being used for both DL and UL transmissions at the same time), thereby reducing co-channel interference on the pilot tones, where the OFDM sub- carriers for UL and DL transmissions are the same.

In some examples disclosed herein, the pilot tone pattern includes utilizing different

OFDM sub-carriers for UL and DL transmissions at different points in time, thereby ensuring that DL signals are not being received at the same time and/or using the same OFDM sub- carriers as UL signals. For example, an AP may transmit a pilot tone pattern to an UL STA (e.g., a STA that is transmitting uplink packets to the AP) and a DL STA (e.g., a STA that is receiving downlink packets from the AP), where the pilot tone pattern includes reserving a first set of OFDM sub-carriers for UL transmission and a second set of OFDM sub-carriers for the DL transmissions. In this manner, there is no overlap between the DL signals and the UL signals. In another example, the same OFDM pilot sub-carriers may be used for UL and DL transmissions but at different times (e.g., alternating between UL and DL transmissions using the same pilot sub-carriers at different points in time), thereby eliminating the overlap between the DL signals and the UL signals at any given time. In another example, the pilot tone pattern includes adjusting the sub-carriers used for full-duplex transmissions so that the pilot signal travels across the channel bandwidth (e.g., a pilot sub-carrier travels across two or more OFDM sub-carriers at different points in time). Other pilot tone patterns may additionally or alternatively be used to reduce co-channel interference.

In some examples disclosed herein, the DL STA measures the co-channel interference for the data tones on OFDM sub-carriers that are being used for UL transmission and are not being used for DL transmissions (e.g., the sub-carriers for the DL STA are idle). In this manner, the DL STA can utilize the durations of idle time (e.g., when the OFDM sub-carriers are not being used for UL transmissions and not for DL transmissions) to measure co-channel interference on the data tones. In such examples, the DL STA can transmit the co-channel interference on the data tones measurements to the AP, so that the AP can adjust subsequent full-duplex

transmissions to reduce the co-channel interference on the data tones.

FIG. 1 illustrates communications in using full-duplex wireless local area network Wi-Fi protocols to reduce co-channel interference. The example of FIG. 1 includes an example AP 100, an example AP communication converter 102, an example UL STA 104, example co- channel interference 105, an example DL STA 106, example STA communication converters 108, and an example network 110. Although the illustrated example of FIG. 1 includes two STAs and one network, the example AP 100 may communicate with any number of STAs and any number of networks.

The example AP 100 of FIG. 1 is a device that allows the example STAs 104, 106 to access wirelessly the example network 110. The example AP 100 may be a router, a modem- router, and/or any other device that provides a wireless connection to a network. A router provides a wireless communication link to a STA. The router accesses the network through a wire connection via a modem. A modem-router combines the functionalities of the modem and the router. The example AP 100 includes the example AP communication converter 102 to reduce co-channel interference using a communication protocol for communications with the example STAs 104, 106, as further described below.

The example AP communication converter 102 of FIG. 1 reduces co-channel interference during full-duplex Wi-Fi communications by operating using a pilot tone communication protocol. A pilot tone communication protocol is a protocol that allows the example AP communication converter 102 to utilize the functionalities of the example AP 100 to schedule simultaneous UL and DL transmissions on the same channel using different OFDM sub-carriers (e.g., pilot sub-carriers). For example, the example AP communication converter 102 may facilitate communications using a pilot tone pattern that utilizes a sub-carrier for DL data and a different sub-carrier for UL data, thereby allowing each STA (e.g., the example UL STA 104 and the example DL STA 106) to communicate on clean channels (e.g., non-overlapping channels). In this manner, pilot tone co-channel interference produced by the example UL STA 104 is not heard by (e.g., does not affect) the example DL STA 106. Example pilot tone protocols are further described below in conjunction with FIGS. 10-14.

The example AP communication converter 102 of FIG. 1 utilizes a PHY layer capability exchange protocol during initial communications between the AP 100 and the STAs 104, 106 to verify that the STAs 104, 106 are capable of operating using a selected pilot tone protocol. In response to transmitting a selected pilot tone protocol support request to the example STAs 104, 106 using the PHY, the example AP communication converter 102 listens for a response from the example STAs 104, 106 to determine if the STAs 104, 106 are able or are not able to operate using the selected pilot tone protocol. If the example STAs 104, 106 can operate using the selected pilot tone protocol, the example AP communication converter 102 transmits a trigger frame identifying a pilot tone pattern corresponding to the pilot tone protocol. The pilot tone pattern reserves the sub-carriers that are to be used by each STA 104, 106 at each time during DL/UL transmission (e.g., corresponding to when each device should transmit/receive data packets and when each device should refrain from transmitting/receiving data packets). An example of a PHY and trigger frame that may be generated by the example AP communication converter 102 are further described below in conjunction with FIGS. 8 and 9. The example AP communication converter 102 is further described below in conjunction with FIG. 2.

The example STAs 104, 106 of FIG. 1 are Wi-Fi enabled computing devices. The example STAs 104, 106 may be, for example, a computing device, a portable device, a mobile device, a mobile telephone, a smart phone, a tablet, a gaming system, a digital camera, a digital video recorder, a television, a set top box, an e-book reader, and/or any other Wi-Fi enabled device. In the illustrated example, the example STA 104 is a UL STA (e.g., transmitting uplink packets to the example AP 100) and the example STA 106 is a DL STA (e.g., receiving downlink packets from the example AP 100). However, the example STAs 104, 106 may transition between UL and DL (e.g., the example UL STA 104 may additionally or alternatively receive downlink packets from the example AP 100 and the example DL ST A 106 may additionally or alternatively transmit uplink packets to the example AP 100). The example STAs 104, 106 include the example ST A communication converter 108 that utilizes the functionality of the example STAs 104, 106 to connect and communicate with a Wi-Fi AP (e.g., the example AP 100) to reduce co-channel interference using a communication protocol to access a network (e.g., the example network 110) using UL and DL data transmissions, as further described below.

The STA communication converter 108 of FIG. 1 reduces co-channel interference during full-duplex Wi-Fi communications by facilitating communications using a pilot tone

communication protocol. Initially, the example STA communication converter 108 utilizes the functionalities of the example STAs 104, 106 to receive a pilot tone protocol support request from the example AP 100. The example STA communication converter 108 processes the pilot tone protocol support request to determine if the STAs 104, 106 support the pilot tone protocol corresponding to the support request. If the example STA communication converter 108 determines that the pilot tone protocol is supported, the STA communication converter 108 utilizes the functionalities of the example STAs 104, 106 to transmit a response indicating that the pilot tone protocol is supported; else, the STA communication converter 108 utilizes the functionalities of the example STAs 104, 106 to transmit a response indicating that the pilot tone protocol is not supported. If the STAs 104, 106 transmit a successful response (e.g., indicating that the pilot tone protocol is supported), the example STAs 104, 106 receive a pilot tone pattern corresponding to the pilot tone protocol. The example STA communication converter 108 controls the STAs 104, 106 to operate (e.g., receives DL transmissions and/or transmits UL transmissions) based on the received pilot tone protocol. In some examples, the STA

communication converter 108 (e.g., of the example DL STA 106) utilizes the functionalities of the example STAs 104, 106 to measure co-channel interference at UL sub-carriers (e.g., sub- carriers being used for UL data) while the sub-carriers for the STA (e.g., the example DL STA 106) are idle (e.g., not being used for DL data). In this manner, once the full-duplex

transmission is complete, the example STA communication converter 108 can transmit co- channel interference values to the example AP 100 (e.g., via an acknowledgement or other data packet). In this manner, the example AP 100 can adjust transmissions to reduce co-channel interference in subsequent data transmissions. The example STA communication converter 108 is further described below in conjunction with FIG. 3. The example network 110 of FIG. 1 is a system of interconnected systems exchanging data. The example network 110 may be implemented using any type of public or private network such as, but not limited to, the Internet, a telephone network, a local area network (LAN), a cable network, and/or a wireless network. To enable communication via the network 110, the example Wi-Fi AP 100 includes a communication interface that enables a connection to an Ethernet, a digital subscriber line (DSL), a telephone line, a coaxial cable, or any wireless connection, etc.

FIG. 2 is a block diagram of an example implementation of the example AP

communication converter 102 of FIG. 1, disclosed herein, to reduce co-channel interference during full-duplex Wi-Fi communications. The example AP communication converter 102 includes an example pilot tone determiner 200, an example transmitter 202, an example receiver 204, and an example future scheduling adjuster 206.

The example pilot tone determiner 200 of FIG. 2 determines which pilot tone protocol to use and develops a pilot tone pattern for the selected pilot tone protocol. As described above, a pilot tone protocol is a protocol that allows full-duplex scheduling of the example UL STA 104 and the example DL STA 106 of FIG. 1 (e.g., allowing the UL STA 104 to transmit UL data packets to the AP 100 at the same time as the DL STA 106 receives DL packets from the AP 100) without the risk of pilot tone co-channel interference from the example UL STA 104 affecting the DL packets. In some examples, the pilot tone determiner 200 determines the pilot tone protocol/pattern based on a preset configuration by a user and/or manufacturer. In some examples, the pilot tone determiner 200 determines the pilot tone protocol/pattern based on available resources. For example, a first pilot tone protocol may require additional memory (e.g., of the example STAs 104, 106 or the example AP 100) to store data packets while a second pilot tone protocol may require additional sub-carriers to be clear for transmission. In such an example, the pilot tone determiner 200 may select a pilot tone protocol/pattern based on the resources available to it. The benefits and limitations of example pilot tone protocols are described below in conjunction with FIGS. 10-14. Additionally, the example pilot tone determiner 200 determines based on responses from the example STAs 104, 106 if a selected pilot tone protocol is supported or not.

The example transmitter 202 of FIG. 2 utilizes the functionality of the example AP 100 to transmit information to the example STAs 104, 106. In some examples, the transmitter 202 transmits PHY packets indicating a selected pilot pattern protocol (e.g., a pilot pattern support request) to the example STAs 104, 106. In some examples, the transmitter 202 transmits pilot tone pattern data using, for example, a trigger frame to the example STAs 104, 106. In some examples, the transmitter 202 transmits DL data packets to the example DL STA 106.

The example receiver 204 of FIG. 2 utilizes the functionality of the example AP 100 to receive information from the example STAs 104, 106. In some examples, the receiver 204 receives responses to the pilot pattern support requests identifying whether the selected pilot pattern protocol is supported by the example STAs 104, 106. In some examples, the receiver 204 receives co-channel interference from the example DL STA 106. In some examples, the receiver 204 receives UL data packets from the example UL STA 104.

The example future scheduling adjuster 206 of FIG. 2 adjusts future full-duplex scheduling and/or resource allocations (e.g., modulation and coding scheme (MCS), transmit power, etc.) based on received co-channel interference values. In this manner, the example AP 102 can further reduce co-channel interference in subsequent full-duplex data transmissions without scheduling and exchanging additional frames, thereby conserving cost, time, and energy.

FIG. 3 is a block diagram of an example implementation of the example STA

communication converter 108 of FIG. 1, disclosed herein, to reduce co-channel interference during full-duplex Wi-Fi communications. The example STA communication converter 108 includes an example receiver 300, an example PHY processor 302, an example trigger frame processor 304, an example UL/DL converter 306, an example interference determiner 308, and an example transmitter 310.

The example receiver 300 of FIG. 3 utilizes the functionality of the example STA 104, 106 to receive information from the example AP 100. In some examples, the receiver 300 receives PHY packets indicating a selected pilot pattern protocol (e.g., a pilot pattern support request) from the AP 100. In some examples, the receiver 300 receives pilot tone pattern data using, for example, a trigger frame from the AP 100. In some examples, the receiver 300 receives DL data packets from the example AP 100.

The example PHY processor 302 of FIG. 3 processes a received PHY packet to identify the pilot tone protocol selected by the example AP 100. In some examples, the PHY packet may include one or more bits that correspond to different pilot tone protocols (e.g., a bit value of '0' may correspond to a first protocol and a bit value of Ί ' may correspond to a second protocol). In such examples, the PHY processor 302 processes the PHY to identify the bit corresponding to pilot tone protocols and determines the select pilot tone protocol based on the value

corresponding to the bit. Once the protocol has been identified, the example PHY processor 302 determines if the example STAs 104, 106 support the pilot protocol (e.g., if the STAs 104, 106 can operate under the identified protocol). The example PHY processor 302 generates a response based on whether or not the example STAs 104, 106 support the identified protocol.

The example trigger frame processor 304 of FIG. 3 processes trigger frames transmitted by the example AP 100. In some examples, a trigger frame includes one or more bits identifying the example STAs 104, 106 and/or corresponding to a mode of operation (e.g., DL or UL). Additionally, the trigger frame may include one or more bits corresponding to a pilot tone pattern. In this manner, the example STAs 104, 106 can perform full-duplex communications with the example AP 100 using the pilot tone pattern to reduce or otherwise eliminate pilot tone co-channel interference produced by the UL transmissions.

The example UL/DL converter 306 of FIG. 3 facilitates UL and/or DL data transmissions with the example AP 100 based on the pilot tone protocol/pattern. The example UL/DL converter 306 determines which sub-carriers to use at which point in time for DL reception or UL transmission based on the pilot tone pattern. In some examples, when the pilot tone pattern does not correspond to active use of a sub-carrier at a particular time, the example UL/DL converter 306 leaves the operation at the sub-carrier idle.

The example interference determiner 308 of FIG. 3 measures the interference on a sub- carrier reserved for UL transmission of the example UL STA 104. Because pilot protocols may prevent overlapping of sub-carriers (e.g., when the UL STA 104 transmits UL packets using a sub-carrier at a point in time, the DL STA 106 will refrain from receiving DL packets (e.g., will not receive DL packets) using the same sub-carrier index), the example interference determiner 308 may measure the co-channel interference produced by the UL STA 104 on the UL dedicated sub-carriers, which are idle (e.g., or unused) for the DL STA 106. For example, the interference determiner 308 may measure the interference using a signal strength measurement or other channel assessment technique. The example interference determiner 308 may generate a data packet to transmit the interference values to the example AP 100 once the full-duplex

transmission is complete (e.g., in an acknowledgement or other response). The example transmitter 310 of FIG. 3 utilizes the functionality of the example ST As 104, 106 to transmit information to the example AP 100. In some examples, the transmitter 310 transmits responses to the pilot pattern support requests identifying whether the selected pilot pattern protocol is supported by the example STAs 104, 106. In some examples, the transmitter 310 transmits co-channel interference to the example AP 100. In some examples, the transmitter 310 transmits UL data packets to the example AP 100. In some examples, the transmitter 310 transmits acknowledgement packets to the example AP 100.

While an example manner of implementing the example AP communication converter 102 and the example STA communication converter 108 of FIG. 1 is illustrated in FIGS. 2 and 3, one or more of the elements, processes and/or devices illustrated in FIGS. 2 and 3 may be combined, divided, re-arranged, omitted, eliminated and/or implemented in any other

way. Further, the example pilot tone determiner 200, the example transmitter 202, the example receiver 204, the example future scheduling adjuster 206, and/or more generally the example AP communication converter 102 of FIG. 2 and the example receiver 300, the example PHY processor 302, the example trigger frame processor 304, the example UL/DL converter 306, the example interference determiner 308, the example transmitter 310, and/or, more generally, the example STA communication converter 108 of FIG. 3 may be implemented by hardware, software, firmware and/or any combination of hardware, software and/or firmware. Thus, for example, any of the example pilot tone determiner 200, the example transmitter 202, the example receiver 204, the example future scheduling adjuster 206, and/or more generally the example AP communication converter 102 of FIG. 2 and the example receiver 300, the example PHY processor 302, the example trigger frame processor 304, the example UL/DL converter 306, the example interference determiner 308, the example transmitter 310, and/or, more generally, the example STA communication converter 108 of FIG. 3 could be implemented by one or more analog or digital circuit(s), logic circuits, programmable processor(s), application specific integrated circuit(s) (ASIC(s)), programmable logic device(s) (PLD(s)) and/or field

programmable logic device(s) (FPLD(s)). When reading any of the apparatus or system claims of this patent to cover a purely software and/or firmware implementation, at least one of the example, the example pilot tone determiner 200, the example transmitter 202, the example receiver 204, the example future scheduling adjuster 206, and/or more generally the example AP communication converter 102 of FIG. 2 and the example receiver 300, the example PHY processor 302, the example trigger frame processor 304, the example UL/DL converter 306, the example interference determiner 308, the example transmitter 310, and/or, more generally, the example STA communication converter 108 of FIG. 3 is/are hereby expressly defined to include a non-transitory computer readable storage device or storage disk such as a memory, a digital versatile disk (DVD), a compact disk (CD), a Blu-ray disk, etc., including the software and/or firmware. Further still, the example AP communication converter 102 of FIG. 2 and/or the example STA communication converter 108 of FIG. 3 may include one or more elements, processes and/or devices in addition to, or instead of, those illustrated in FIGS. 2 and/or 3, and/or may include more than one of any or all of the illustrated elements, processes and devices.

Flowcharts representative of example machine readable instructions for implementing the example AP communication converter 102 of FIG. 2 is shown in FIG. 4 and flowcharts representative of example machine readable instructions for implementing the example STA communication converter 108 of FIG. 3 is shown in FIGS. 5-7. In this example, the machine readable instructions comprise a program for execution by a processor such as the processor 1512, 1612 shown in the example processor platform 1500, 1600 discussed below in connection with FIGS. 15 and 16. The program may be embodied in software stored on a non-transitory computer readable storage medium such as a CD-ROM, a floppy disk, a hard drive, a digital versatile disk (DVD), a Blu-ray disk, or a memory associated with the processor 1512, 1612, but the entire program and/or parts thereof could alternatively be executed by a device other than the processor 1512, 1612 and/or embodied in firmware or dedicated hardware. Further, although the example program is described with reference to the flowchart illustrated in FIGS. 4-7, many other methods of implementing the example AP communication converter 102 and/or the example STA communication converter 108 may alternatively be used. For example, the order of execution of the blocks may be changed, and/or some of the blocks described may be changed, eliminated, or combined. Additionally or alternatively, any or all of the blocks may be implemented by one or more hardware circuits (e.g., discrete and/or integrated analog and/or digital circuitry, a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), a comparator, an operational-amplifier (op-amp), a logic circuit, etc.) structured to perform the corresponding operation without executing software or firmware.

As mentioned above, the example processes of FIGS. 4-7 may be implemented using coded instructions (e.g., computer and/or machine readable instructions) stored on a non- transitory computer and/or machine readable medium such as a hard disk drive, a flash memory, a read-only memory, a compact disk, a digital versatile disk, a cache, a random-access memory and/or any other storage device or storage disk in which information is stored for any duration (e.g., for extended time periods, permanently, for brief instances, for temporarily buffering, and/or for caching of the information). As used herein, the term non-transitory computer readable medium is expressly defined to include any type of computer readable storage device and/or storage disk and to exclude propagating signals and to exclude transmission media.

"Including" and "comprising" (and all forms and tenses thereof) are used herein to be open ended terms. Thus, whenever a claim lists anything following any form of "include" or

"comprise" (e.g., comprises, includes, comprising, including, etc.), it is to be understood that additional elements, terms, etc., may be present without falling outside the scope of the corresponding claim. As used herein, when the phrase "at least" is used as the transition term in a preamble of a claim, it is open-ended in the same manner as the term "comprising" and

"including" are open ended.

FIG. 4 is an example flowchart 400 representative of example machine readable instructions that may be executed by the example AP communication converter 102 of FIGS. 1 and 3 to reduce co-channel interference during full-duplex Wi-Fi communications. Although the example of FIG. 4 is described in conjunction with the example AP 100 in the network of FIG. 1, the instructions may be executed by any type of AP in any network.

At block 402, the example pilot tone determiner 200 determines if the AP 100 is configured to operate using a predefined pilot tone protocol. As described above, a user and/or manufacture may preset a pilot tone protocol to use during full-duplex Wi-Fi communications. If the example pilot tone determiner 200 determines that the AP 100 is configured to operate using a predefined pilot tone protocol (block 402: YES), the example pilot tone determiner 200 utilizes the functionalities of the AP 100 to transmit a pilot protocol support request

corresponding to the predefined pilot tone protocol to the example STAs 104, 106 using a PHY packet (block 404). If the example pilot tone determiner 200 determines that the AP 100 is not configured to operate using a predefined pilot tone protocol (block 402: NO), the example pilot tone determiner 200 determines AP resource availability (block 406). The AP resource availability may include sub-carrier channels, memory resources, processing power, antenna power, etc., that are available to the example AP 100. At block 408, the example pilot tone determiner 200 selects a pilot tone protocol based on the AP resource availability. For example, if the AP memory resources are low, the example pilot tone determiner 200 may select a pilot tone protocol corresponding to low memory consumption. In another example, if the available sub-carriers are limited, the example pilot tone determiner 200 may select a pilot tone protocol corresponding to a smaller number of used sub-carriers. At block 410, the example pilot tone determiner 200 instructions the example transmitter 202 to transmit a pilot protocol support request corresponding to the selected pilot tone protocol to the example STAs 104, 106 using a PHY packet.

At block 412, the example receiver 204 receives one or more pilot protocol support responses from one or more STAs (e.g., the example STAs 104, 106). At block 414, the example pilot tone determiner 200 determines if the pilot protocol support response(s) correspond to the selected pilot tone protocol (e.g., via the PHY). For example, the pilot tone determiner 200 may process the received PHY packet to determine if one or more bits corresponding to the pilot tone protocol match the selected pilot tone protocol. If the one or more bits match the pilot tone protocol, the example pilot tone determiner 200 determines that the pilot protocol support response corresponds to the selected pilot tone protocol. If the example pilot tone determiner 200 determines that the pilot protocol support response(s) do not correspond to the selected pilot tone protocol (block 414: NO), the example AP 100 facilitates DL/UL communications without using the selected pilot tone protocol (block 416). Instead, the example AP communication converter 102 may select a different pilot tone protocol or may proceed with traditional full-duplex techniques.

If the example pilot tone determiner 200 determines that the pilot protocol support response(s) correspond to the selected pilot tone protocol (block 414: YES), the example pilot tone determiner 200 determines a pilot tone pattern corresponding to the pilot tone protocol (block 418). The pilot tone pattern identifies which sub-carriers at which times will be used for DL transmissions and which sub-carriers at which times will be used for UL transmissions. In some examples, the pilot tone pattern ensures that no DL and UL transmissions utilize the same sub-carrier at the same time.

At block 420, the example transmitter 202 transmits the pilot tone pattern to the example STAs 104, 106. At block 422, the example AP 100 facilitates DL/UL communications based on the pilot tone pattern. For example, the AP 100 transmits DL packets to the example DL STA 106 at the times and sub-carriers identified in the pilot tone pattern and receives UL packets from the example UL STA 104 while refraining from (e.g., not) transmitting DL packets at the times and sub-carriers identified in the pilot tone pattern. At block 424, the example future scheduling adjuster 206 determines if the example receiver 204 has received co-interference values from the example DL STA 106. If the example future scheduling adjuster 206 determines that the co- interference values have not been received from the example DL STA 106 (block 424: NO), the process ends. If the example future scheduling adjuster 206 determines that the co-interference values have been received from the example DL STA 106 (block 424: YES), the example future scheduling adjuster 206 adjusts the future scheduling of the example STAs 104, 106 based on the received co-interference values (block 426).

FIG. 5 is an example flowchart 500 representative of example machine readable instructions that may be executed by the example STA communication converter 108 of FIG. 2 to reduce co-channel interference during full-duplex Wi-Fi communications. Although the example of FIG. 5 is described in conjunction with one of the example STAs 104, 106 in the network of FIG. 1, the instructions may be executed by any type of STA in any network.

At block 502, the example receiver 300 receives a pilot protocol support request from the example AP 100 using the PHY. As described below in conjunction with FIG. 8, the PHY includes data packets that identify a pilot protocol selected by the example AP 100. At block 503, the example PHY processor 302 processes the PHY to determine the pilot protocol corresponding to the PHY layer. For example, the PHY processor 302 may identify one or more bits in the PHY layer corresponding to the pilot precools and identify the selected pilot protocol based on the value identified in the one or more bits.

At block 504, the example PHY processor 302 determines if the STA (e.g., STA 104 or STA 106) supports the pilot tone protocol corresponding to the request. If the example PHY processor 302 determines that the STA does not support the pilot tone protocol corresponding to the request (block 504: NO), the transmitter 310 transmits a response to the AP 100 indicating that the pilot tone protocol is not supported by the STA (block 506). For example, the transmitter 310 may transmit a PHY layer back to the AP 100 where the bit corresponding to the pilot tone protocol has been changed, thereby signaling that the STA does not support the pilot protocol. At block 508, example UL/DL converter 306 facilitates communications with the AP 100 without using the pilot tone protocol selected by the AP 100 (e.g., identified in the received pilot protocol support request).

If the example PHY processor 302 determines that the STA does support the pilot tone protocol corresponding to the request (block 504: YES), the transmitter 310 transmits a response to the AP 100 indicating that the pilot tone protocol is supported by the STA (block 510). At block 512, the example receiver 300 receives a trigger frame from the example AP 100. As described below in conjunction with FIG. 9, the trigger frame includes the pilot tone pattern used by the STA to facilitate UL and/or DL transmissions. At block 514, the example trigger frame processor 304 determines if the trigger frame corresponds to UL or DL transmissions. For example, the trigger frame may include an identifier for the UL STA 104 with one or more bits corresponding to an UL transmission and may include an identifier for the DL STA 106 with one or more bits corresponding to a DL transmission, as further described below in conjunction with FIG. 9.

If the example trigger frame processor 304 determines that the trigger frame corresponds to UL transmissions (block 514: UL), the example trigger frame processor 304 determines the UL pilot tone pattern based on the trigger frame (block 516). For example, the trigger frame processor 304 may identify the one or more bits corresponding to the pilot tone pattern and determine the pattern based on the value stored in the one or more bits. At block 518, the example STA communication converter 108 processes packets according to the UL pilot tone pattern, as further described below in conjunction with FIG. 6.

If the example trigger frame processor 304 determines that the trigger frame corresponds to DL transmissions (block 514: DL), the example trigger frame processor 304 determines the DL pilot tone pattern based on the trigger frame (block 520). For example, the trigger frame processor 304 may identify the one or more bits corresponding to the pilot tone pattern and determine the pattern based on the value stored in the one or more bits. At block 522, the example STA communication converter 108 transmits UL packets according to the UL pilot tone pattern, as further described below in conjunction with FIG. 7. In some examples, the reception of the DL packets includes determining co-channel interference, as further described below in conjunction with FIG. 7.

At block 524, the example interference determiner 308 determines if the co-channel interference was determined. If the example interference determiner 308 determines that the co- channel interference was not determined (block 524: NO), the process ends. If the example interference determiner 308 determines that the co-channel interference was not determined (block 524: NO), the example transmitter 310 transmits the co-channel interference values to the example AP 100 (block 526). In some examples, the transmitter 310 transmits the co-channel interference values to the AP 100 as part of an acknowledgment data packet and/or a separate data packet.

FIG. 6 is an example flowchart 518 representative of example machine readable instructions that may be executed by the example ST A communication converter 108 of FIG. 2 to transmit UL packets according to a UL pilot tone pattern, as described above in conjunction with block 518 of FIG. 5.

At block 602, the example UL/DL converter 306 determines the sub-carrier(s) for DL/UL transmission at the current time based on the pilot tone pattern. For example, at a first time, the pilot tone pattern may reserve a first and third sub-carrier for DL transmission and a second and fourth sub-carrier for UL transmission. At a second time, the sub-carriers may switch or change to other sub-carriers. In another example, the first time may correspond to DL transmissions and the second time may correspond to UL transmissions. At block 604, the UL/DL converter 306 determines the UL sub-carrier(s) corresponding to transmission of UL packets based on the pilot tone pattern (e.g., which sub-carrier(s) should be used to transmit UL packets at the current time). At block 606, the example transmitter 310 transmits the UL packets using the determined UL sub-carrier(s) while leaving the DL sub-carrier(s) (e.g., the sub-carrier(s) corresponding to DL packets to a DL STA) idle.

At block 608, the example UL/DL converter 306 determines if the full-duplex

transmission is complete. If the example UL/DL converter 306 determines that the full-duplex transmission is not complete (block 608: NO), the process returns to block 602 to facilitate UL transmissions at a subsequent time(s) until the UL transmission is complete. If the example

UL/DL converter 306 determines that the full-duplex transmission is complete (block 608: YES), the example receiver 300 receives an acknowledgement from the example AP 100 confirming the reception of the transmitted UL packets (block 610).

FIG. 7 is an example flowchart 522 representative of example machine readable instructions that may be executed by the example STA communication converter 108 of FIG. 2 to receive DL packets according to a UL pilot tone pattern, as described above in conjunction with block 522 of FIG. 5.

At block 702, the example UL/DL converter 306 determines the pilot sub-carrier(s) for DL/UL transmission at the current time based on the pilot tone pattern. For example, at a first time, the pilot tone pattern may reserve a first and third sub-carrier for DL transmission and a second and fourth sub-carrier for UL transmission. At a second time, the UL/DL converter 306 may switch the sub-carriers of change to different sub-carriers. In another example, the first time may correspond to DL transmissions and the second time may correspond to UL transmissions. At block 704, the UL/DL converter 306 determines the DL sub-carrier(s) corresponding to receiving DL packets based on the pilot tone pattern (e.g., which sub-carrier(s) should be used to receive DL packets at the current time). At block 706, the example receiver 300 receives the DL packets using the determined DL sub-carrier(s) while leaving the UL sub-carrier(s) (e.g., the sub- carriers) corresponding to UL packets from a UL STA) idle.

At block 708, the interference determiner 308 determines if co-channel interference determination is enabled. The example interference determiner 308 may determine that co- channel interference determination is enabled based on instructions from the AP (e.g., in the PHY layer, the trigger frame, and/or another data packet) or based on a configuration of the STAs 104, 106. If the example interference determiner 308 determines that co-cannel interference determination is not enabled (block 708: NO), the process continues to block 714, as further described below. If the example interference determiner 308 determines that co-cannel interference determination is enabled (block 708: YES), the example interference determiner 308 determines the UL sub-carrier(s) corresponding to the UL packets being transmitted by a UL STA (e.g., the example UL STA 104) based on the pilot tone pattern (block 710). At block 712, the example interference determiner 308 utilizes the functionalities of the DL STA 106 to measure the co-channel interference of the UL sub-carrier(s) at the current time. The

interference determiner 308 generates a value corresponding to the measured co-channel interference.

At block 714, the example UL/DL converter 306 determines if the full-duplex

transmission ceased. If the example UL/DL converter 306 determines that the full-duplex transmission has not ceased (block 714: NO), the process returns to block 702 to receive DL packets and/or measure co-channel interference at a subsequent time. If the example UL/DL converter 306 determines that the full-duplex transmission has ceased (block 714: YES), the example interference determiner 308 determines if the co-channel interference was determined (e.g., the co-channel interference values at the UL sub-channels of the full-duplex transmission) (block 716). If the example interference determiner 308 determines that the co-channel interference was not determined (block 716: NO), the process ends. If the example interference determiner 308 determines that the co-channel interference was determined (block 716: YES), the example transmitter 310 transmits the co-channel interference values to the example AP 100 (block 718).

FIG. 8 is an example PHY layer 800 used by the example access point 100 and the example STAs 104, 106 of FIG. 1 to determine if a pilot tone algorithm is enabled. Although, the example PHY layer 800 corresponds to the 802.1 lax standard, any number or location of bits for a PHY layer in any Wi-Fi standard (e.g., a non-1 lax-dependent PHY generation, a new next big thing Wi-Fi generation, etc.) may be used to identify whether a pilot tone algorithm is enabled. The example PHY layer 800 includes an example traveling pilot support bit 802 represented by bit number B65.

The example traveling pilot support bit 802 of FIG. 8 is a bit that identifies whether or not traveling pilot support is enabled. Although the example traveling pilot support bit 802 corresponds to a single bit in position B65, any number of bits and/or any bit position may alternatively be used as a traveling pilot support bit. In some examples, the traveling pilot support bit 802 may be depended on, or be used in combination with, other capabilities (e.g., full-duplex capability, self-interference cancellation, receiver capability, next generation 802.11 capability, etc.). For example, the traveling pilot support bit 802 may or may not be used, depending on other capabilities supported by the example AP 100 and/or STAs 104, 106. In some examples, the traveling pilot support bit 802 may be mandated if the dependent capabilities (e.g., full-duplex) is supported.

When the example AP 100 sets the traveling pilot support bit 802 to "1," for example, the AP 100 is indicating that the AP 100 can generate a traveling pilot for DL transmissions and process traveling pilot for UL transmissions. In such an example, when the example AP 100 sets the traveling pilot support bit 802 to "0," the AP 100 is indicating that the AP 100 does not support traveling pilot. When the example ST A 104, 106 sets the traveling pilot support bit 802 to "1," for example, the STA 104, 106 is indicating that the STA 104, 106 can generate a traveling pilot for UL transmissions and process traveling pilot for DL transmissions. In such an example, when the example STA 104, 106 sets the traveling pilot support bit 802 to "0," the STA 104, 106 is indicating that the STA 104, 106 does not support traveling pilot.

FIG. 9 is an example trigger frame 900 that may be used by the example AP 100 to identify a pilot tone pattern to the example STAs 104, 106. Although the example trigger frame 900 is formatted as a multi-user full-duplex trigger type (e.g., as indicating by an example trigger type field 901, the example trigger frame 900 may be formatted to any type. The example trigger frame 900 keeps the example trigger type field 901 (e.g., corresponding to the multi-user full-duplex trigger type), an example uplink field 902, an example UL traveling pilot pattern field 904, an example downlink field 906, and an example DL traveling pilot pattern field 908. Additionally or alternatively, the trigger frame 900 may include any number of uplink fields and/or any number of downlink fields for any number of connected STAs.

The example uplink field 902 of FIG. 9 includes a bit (e.g., UL(0)) that indicates the uplink field 902 as dedicated to UL transmission for the example UL STA 104 (e.g., when the UL(0) bit is 'Ο,' the field corresponds to UL transmission). The example uplink field 902 further includes one or more bits in the UL traveling pilot pattern field 904 corresponding to the traveling pilot pattern to be utilized by the example AP 100. The one or more bits of the example UL traveling pilot pattern field 904 identifies which traveling pilot pattern that the UL STA 104 should use (e.g., which OFDM sub-carriers to use for transmission of UL data packets by the UL STA 104 at particular times). In some examples, the size of the UL traveling pilot pattern field 904 may depend on the number of available pilot patterns (e.g., each value corresponding to a distinct traveling pilot pattern). In some examples, the traveling pilot patterns can be predetermined and stored in a lookup table at the example AP 100 and/or the example STAs 104, 106, where the traveling pilot pattern field acts as an index of the available traveling pilot patterns.

The example downlink field 906 of FIG. 9 includes a bit (e.g., DL(1)) that indicates the downlink field 906 as dedicated to DL transmission for the example DL STA 106 (e.g., when the DL(1) bit is Ί,' the field corresponds to DL transmission). The example downlink field 906 further includes one or more bits in the DL traveling pilot pattern field 908 corresponding to the traveling pilot pattern to be utilized by the example AP 100. The one or more bits of the example DL traveling pilot pattern field 908 identifies which traveling pilot pattern that the DL STA 106 should use (e.g., which OFDM sub-carriers to use for the reception of DL data packets by the DL STA 106 at particular times). In some examples, the size of the DL traveling pilot pattern field 908 may depend on the number of available pilot patterns (e.g., each value corresponding to a distinct traveling pilot pattern). In some examples, the traveling pilot patterns can be predetermined and stored in a lookup table at the example AP 100 and/or the example STAs 104, 106, where the traveling pilot pattern field acts as an index of the available traveling pilot patterns.

FIG. 10 is an example pilot tone pattern 1000 that may be utilized by the example AP 100 and the example STAs 104, 106 for full-duplex transmissions to reduce and/or measure co- channel interference. The example pilot tone pattern 1000 includes an example UL transmission pattern 1002 and an example DL transmission pattern 1004. The example pilot tone pattern 1000 alternates pilots in the frequency-domain. Although the example pilot tone pattern 1000 corresponds to full-duplex transmissions using particular OFDM sub-carrier indexes (e.g., 21, 7, -7, -21), the pilot tone pattern 1000 may include any number and/or combination of OFDM sub- carrier indexes.

As describe above, the example pilot tone pattern 1000 of FIG. 10 includes full-duplex transmissions using four OFDM sub-carrier indexes (e.g., 21, 7, -7, -21). Because UL transmission from the example UL STA 104 causes interference on the DL packets to the example DL STA 106, the example UL transmission pattern 1002 includes slot reservations for transmitting UL packets at indexes that are not being used in the DL transmission pattern 1004 and the DL transmission pattern 1004 includes slot reservations for receiving DL packets at indexes that are not be used in the UL transmission pattern 1002. For example, at the OFDM symbol index 1 (e.g., time 1), the example UL transmission pattern 1002 includes transmitting UL packets using the sub-carriers at the 7 and -7 OFDM sub-carrier indexes, leaving the 21 and - 21 OFDM sub-carrier indexes idle, and the DL transmission pattern 1004 includes receiving DL packets using the sub-carriers at the 21 and -21 OFDM sub-carrier indexes, leaving the sub- carriers at the 7 and -7 OFDM sub-carrier indexes idle.

At the OFDM symbol index 2 (e.g., time 2), the example UL transmission pattern 1002 including switching the transmission of the UL packets to the sub-carriers at the 21 and -21 OFDM sub-carrier indexes and the DL transmission pattern 1004 includes switching the reception of the DL packets to the sub-carriers at the 7 and -7 OFDM sub-carrier indexes. As time goes on, the example pilot tone pattern 1000 switches between the OFDM carrier indexes to avoid an OFDM carrier index from being used for both UL and DL transmissions at the same time. Alternatively, any other switching pattern may be used to ensure that an OFDM carrier index is not being used for both UL and DL transmissions at the same time. In some examples, the UL transmission pattern 1002 and the DL transmission pattern 1004 do not switch OFDM sub-carrier index with time, but rather maintains OFDM sub-carrier indexes such that the UL and DL transmissions are not being done on the same OFDM sub-carrier index at the same time. In some examples, as described above, the example DL ST A 106 may measure the co-channel interference caused by UL transmissions using the OFDM sub-carrier indexes being used for UL (e.g., the OFDM sub-carrier indexes that are being used for UL, but are idle for the DL STA 106).

FIG. 11 is an alternative example pilot tone pattern 1100 that may be utilized by the example AP 100 and the example STAs 104, 106 for full-duplex transmissions to reduce and/or measure co-channel interference. The example pilot tone pattern 1100 includes an example UL transmission pattern 1102 and an example DL transmission pattern 1104. The example pilot tone pattern 1100 alternates pilots in the time-domain. Although the example pilot tone pattern 1100 corresponds to full-duplex transmissions using particular OFDM sub-carrier indexes (e.g., 21, 7, -7, -21), the pilot tone pattern 1100 may include any number and/or combination of OFDM sub-carrier indexes.

As describe above, the example pilot tone pattern 1100 of FIG. 11 includes full-duplex transmissions using four OFDM sub-carrier indexes (e.g., 21, 7, -7, -21). Because UL transmission from the example UL STA 104 causes interference on the DL packets to the example DL STA 106, the example UL transmission pattern 1102 includes slot reservations for transmitting UL packets at indexes that are not being used in the DL transmission pattern 1104 and the DL transmission pattern 1104 includes slot reservations for receiving DL packets at indexes that are not be used in the UL transmission pattern 1102. For example, at the OFDM symbol index 1 (e.g., time 1), the example UL transmission pattern 1102 includes transmitting UL packets using the sub-carriers at the 21, 7, -7, and -21 OFDM sub-carrier indexes and the DL transmission pattern 1104 refrains from receiving DL packets (e.g., leaving the sub-carriers at the 21, 7, -7, and -21 OFDM sub-carrier indexes idle). In this manner, the first OFDM symbol index (e.g., time 1) is dedicated to the example UL transmission pattern 1102. At the OFDM symbol index 2 (e.g., time 2), the example UL transmission pattern 1102 refrains from transmitting UL packets and the DL transmission pattern 1104 includes receiving the DL packets at the sub-carriers at the 21, 7, -7, and - 21 OFDM sub-carrier indexes. As time goes on, the example pilot tone pattern 1100 switches between UL transmission using the dedicated OFDM sub-carrier indexes and DL transmission using the dedicated OFDM sub- carrier indexes to avoid an OFDM carrier index from being used for both UL and DL

transmissions at the same time. In some examples, as described above, the example DL STA 106 may measure the co-channel interference caused by UL transmissions using the OFDM sub- carrier indexes being used for UL.

FIG. 12 is an example traveling pilot tone pattern 1200 that may be utilized by the example AP 100 and the example STAs 104, 106 for full-duplex transmissions to and/or measure reduce co-channel interference. The example traveling pilot tone pattern 1200 includes an example UL transmission pattern 1202 and an example DL transmission pattern 1204. The example traveling pilot tone pattern 1200 alternates pilots in the time-domain. Although the example traveling pilot tone pattern 1200 corresponds to full-duplex transmissions using particular OFDM sub-carrier indexes (e.g., 21, 20, 19, 7, 6, 5, -5, -6, -7, -19, -20, -21), the traveling pilot tone pattern 1200 may include any number and/or combination of OFDM sub- carrier indexes that change in time using any pattern.

The example traveling pilot tone pattern 1200 of FIG. 12 includes full-duplex

transmissions using various OFDM sub-carrier index combinations (e.g., ±21 and ±7, ±20 and ±6, ±19 and ±5) that change with time. Like the pilot tone pattern 1100 of FIG. 11, at the OFDM symbol index 1 (e.g., time 1), the example UL transmission pattern 1202 includes slot reservations for transmitting UL packets using the sub-carriers at the 21, 7, -7, and -21 OFDM sub-carrier indexes and the DL transmission pattern 1204 refrains from receiving DL packets (e.g., leaving the 21, 7, -7, and -21 OFDM sub-carrier indexes idle). In this manner, the first OFDM symbol index (e.g., time 1) is dedicated to the example UL transmission pattern 1202. Additionally, like the example pilot tone pattern 1100 of FIG. 11, at the OFDM symbol index 2 (e.g., time 2), the example UL transmission pattern 1202 refrains from transmitting UL packets and the DL transmission pattern 1204 includes slot reservations for receiving the DL packets at the sub-carriers at the 21, 7, -7, and - 21 OFDM sub-carrier indexes. At the OFDM symbol indexes 3 and 4 (e.g., times 2 and 4), the example traveling pilot tone pattern 1200 of OFDM symbol indexes 1 and 2 is repeated with a different OFDM sub- carrier index (e.g., ±20 and ±6). For example, at the OFDM symbol index 3, the example UL transmission pattern 1202 includes transmitting UL packets using the sub-carriers at the 20, 6, -6, and -20 OFDM sub-carrier indexes and the DL transmission pattern 1204 refrains from receiving DL packets. Additionally, at the OFDM symbol index 4 (e.g., time 4), the example UL transmission pattern 1202 refrains from transmitting UL packets and the DL transmission pattern 1204 includes receiving the DL packets at the sub-carriers at the 20, 6, -6, and - 20 OFDM sub- carrier indexes. In some examples, as described above, the example DL STA 106 may measure the co-channel interference caused by UL transmissions using the OFDM sub-carrier indexes being used for UL.

FIG. 13 is an alternative example traveling pilot tone pattern 1300 that may be utilized by the example AP 100 and the example STAs 104, 106 for full-duplex transmissions to and/or measure reduce co-channel interference. The example traveling pilot tone pattern 1300 includes an example UL transmission pattern 1302 and an example DL transmission pattern 1304. The example traveling pilot tone pattern 1300 alternates pilots in the time-domain. Although the example traveling pilot tone pattern 1300 corresponds to full-duplex transmissions using particular OFDM sub-carrier indexes (e.g., 28, 27, . . . 3, 2, -2, -3, . . .-28), the traveling pilot tone pattern 1300 may include any number and/or combination of OFDM sub-carrier indexes that change in time using any pattern.

The example traveling pilot tone pattern 1300 of FIG. 13 includes full-duplex

transmissions using OFDM sub-carrier index combinations that change in time (e.g., in each OFDM symbol index). For example, at the OFDM symbol index 1 (e.g., time 1), the example UL transmission pattern 1302 includes slot reservations for transmitting UL packets using the sub-carriers at the 21, 7, -7, and -21 OFDM sub-carrier indexes. At the OFDM symbol index 2 (e.g., time 2), the example UL transmission pattern 1302 includes transmitting UL packets using the sub-carriers at the 22, 8, -8, and -22 OFDM sub-carrier indexes. The example UL

transmission pattern 1302 changes the OFDM sub-carrier index combination at each subsequent time.

The example DL transmission pattern 1304 utilizes the same OFDM sub-carrier index combinations as the UL transmission pattern for DL transmission (e.g., the sub-carriers at the 21, 7, -7, and -21 OFDM sub-carrier indexes at time 1, the sub-carriers at the 22, 8, -8, and -22 OFDM sub-carrier indexes at time 2, etc.). However, the DL transmission pattern 1304 includes refraining from receiving DL packets (e.g., not receiving DL packets) on the OFDM sub-carrier indexes (e.g., leaving the OFDM sub-carrier indexes idle) at every other OFDM symbol index (e.g., time). For example, at the OFDM symbol index 2 (e.g., time 2), the example DL transmission pattern 1304 does not correspond to receiving DL packets on the sub-carriers at the -22, -8, 8, and -22 OFDM sub-carrier indexes. In this manner, the example DL station 106 can use the idle OFDM sub-carrier indexes to measure the co-channel interference caused by the UL transmission during the corresponding OFDM symbol index (e.g., time), thereby determining a co-channel interference for multiple sub-carriers (e.g., each interference measurement corresponding to a sub-carrier).

FIG. 14 is an alternative example pilot tone pattern 1400 that may be utilized by the example AP 100 and the example STAs 104, 106 for full-duplex transmissions to reduce and/or measure co-channel interference. The example pilot tone pattern 1400 includes an example UL transmission pattern 1402 including slot reservations for UL transmissions and an example DL transmission pattern 1404 including slot reservations for DL transmissions. The example pilot tone pattern 1400 alternates pilots in the time-domain. Although the example pilot tone pattern 1400 corresponds to UL transmissions using first OFDM sub-carrier indexes (e.g., 21, 7, -7, -21) and DL transmission using second OFDM sub-carrier indexes (e.g., 19, 9, -9, -19), the pilot tone pattern 1400 may include any number and/or combination of OFDM sub-carrier indexes for UL or DL transmissions.

As describe above, the example pilot tone pattern 1400 of FIG. 14 includes UL transmissions using first OFDM sub-carrier indexes (e.g., 21, 7, -7, -21) and DL transmission using second OFDM sub-carrier indexes (e.g., 19, 9, -9, -19). Because UL transmission from the example UL ST A 104 causes interference on the DL packets to the example DL STA 106, the first OFDM sub-carrier indexes are used for UL transmissions and the second OFDM sub-carrier indexes are used for DL transmissions, thereby ensuring that the OFDM sub-carrier indexes for UL and DL transmissions do not overlap. In some examples, as described above, the example DL STA 106 may measure the co-channel interference caused by UL transmissions using the OFDM sub-carrier indexes being used for UL. Although the example pilot tone patterns of FIGS. 10-14 include particular pilot tone patterns, other pilot tone patterns may be utilized by the example AP 100 and the example STAs 104, 106. For example, any of the pilot tone patterns of FIG. 10-14 may be adjusted and/or combined to generate pilot tone patterns that allocate OFDM sub-carrier indexes for both DL and UL to reduce co-channel interference. Additionally, other pilot tone patterns may be used that reduce co-channel interference.

Additionally or alternatively, the pilot tone pattern may include orthogonal pilots in the time domain via orthogonal pilot sequences. For example, the AP 100 can facilitate a pilot protocol where the DL transmission uses a pilot sequence of { 1, 1, 1, -1 } for pilot sub-carrier indexes {-21, -7, 7, 21 } for 20 MHz PHY convergence procedure protocol data unit (PPDU) transmission, for all the OFDM data symbols. In such an example, the pilot protocol may include UL transmissions with an alternating pilot sequence (e.g., { 1, 1, 1, -1 } to {-1, -1, -1, 1 } to { 1, 1, 1, -1 } to {-1, -1, -1, 1 } and so on). For example, the pilot mapping for DL transmission (e.g., Ροι,η) f°^r sub-carrier index k and OFDM symbol index n may correspond to Equation 1 and the pilot mapping for UL transmission (e.g., Ρυι,η) f°^r sub-carrier k and OFDM symbol index n may correspond to Equation 2, as shown below.

^PDL ²n ^~7'7'21} = U_' !' !' -!} ⁿ (Equiation 1)

_D{-2 i -7,7,21} ( {1, 1, 1, -1} if n is odd

¾„ = 1 _{r *} -. -. -> _T ■ (Equation 2)

^UL'ⁿ { {-1, -1, -1, 1} if n is even '

In this manner, the example DL STA 106 can remove the UL pilot signal by adding pilot signal from two consecutive OFDM symbols, as shown below in Equation 3.

pk²n ^'~7'7,21} + ^pk²n i ^'7'21} = {1 - 1, 1 - 1, 1 - 1, -1 + 1} = {0, 0, 0, 0} Vn

(Equation 3)

Accordingly, using the above orthogonal pilots in time domain via orthogonal pilot sequences technique, the example DL STA 106 can cancel out UL pilot signals and obtain phase estimates of UL transmissions without wasting (e.g., nulling or idling) any pilot sub-carrier indexes.

As described above in conjunction with FIG. 2, each pilot tone pattern may correspond to different consumptions of different resources. Accordingly, the example AP 100 may select a pilot tone pattern based on an analysis of the available resources. For example, the example pilot tone patterns 1000, 1100, 1200 reduce the number of pilot tone transmission by half. Accordingly, if the AP 100 does not want to limit the number of pilot tone transmissions, the AP 100 may select a different pilot tone pattern (e.g., the example pilot tone pattern 1400). In another example, the example pilot tone patterns 1200, 1300, 1400 require the reservation of more pilot sub-carriers to execute the patterns. Accordingly, if the AP 100 determines that the additional pilot sub-carriers are unavailable, the AP 100 may select a different pilot tone pattern (e.g., the pilot tone patterns 1000, 1100). Additionally, the example pilot tone pattern 1000 may require additional storage to store a pilot signal until a subsequent signal is received, whereas the example pilot tone pattern 1100 does not require any additional storage. Accordingly, if storage of the example AP 100 is low or unavailable, the example AP 100 may select the example pilot tone pattern 110 for use.

FIG. 15 is a block diagram of an example processor platform 1500 capable of executing the instructions of FIG. 4 to implement the example AP communication converter 102 of FIGS. 1 and 2. The processor platform 1500 can be, for example, a server, a personal computer, a mobile device (e.g., a cell phone, a smart phone, a tablet such as an iPad™), a personal digital assistant (PDA), an Internet appliance, or any other type of computing device.

The processor platform 1500 of the illustrated example includes a processor 1512. The processor 1512 of the illustrated example is hardware. For example, the processor 1512 can be implemented by integrated circuits, logic circuits, microprocessors or controllers from any desired family or manufacturer.

The processor 1512 of the illustrated example includes a local memory 1513 (e.g., a cache). The example processor 1512 of FIG. 15 executes the instructions of FIG. 4 to implement the example pilot tone determiner 200, the example transmitter 202, the example receiver 204, and/or the example future scheduling adjuster 206 of FIG. 2. The processor 1512 of the illustrated example is in communication with a main memory including a volatile memory 1514 and a non-volatile memory 1516 via a bus 1518. The volatile memory 1514 may be

implemented by Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM) and/or any other type of random access memory device. The non-volatile memory 1516 may be

implemented by flash memory and/or any other desired type of memory device. Access to the main memory 1514, 1516 is controlled by a clock controller. The processor platform 1500 of the illustrated example also includes an interface circuit 1520. The interface circuit 1520 may be implemented by any type of interface standard, such as an Ethernet interface, a universal serial bus (USB), and/or a PCI express interface.

In the illustrated example, one or more input devices 1522 are connected to the interface circuit 1520. The input device(s) 1522 permit(s) a user to enter data and commands into the processor 1512. The input device(s) can be implemented by, for example, a sensor, a microphone, a camera (still or video), a keyboard, a button, a mouse, a touchscreen, a track-pad, a trackball, isopoint and/or a voice recognition system.

One or more output devices 1524 are also connected to the interface circuit 1520 of the illustrated example. The output devices 1524 can be implemented, for example, by display devices (e.g., a light emitting diode (LED), an organic light emitting diode (OLED), a liquid crystal display, a cathode ray tube display (CRT), a touchscreen, a tactile output device, and/or speakers). The interface circuit 1520 of the illustrated example, thus, typically includes a graphics driver card, a graphics driver chip or a graphics driver processor.

The interface circuit 1520 of the illustrated example also includes a communication device such as a transmitter, a receiver, a transceiver, a modem and/or network interface card to facilitate exchange of data with external machines (e.g., computing devices of any kind) via a network 1526 (e.g., an Ethernet connection, a digital subscriber line (DSL), a telephone line, coaxial cable, a cellular telephone system, etc.).

The processor platform 1500 of the illustrated example also includes one or more mass storage devices 1528 for storing software and/or data. Examples of such mass storage devices 1528 include floppy disk drives, hard drive disks, compact disk drives, Blu-ray disk drives, RAID systems, and digital versatile disk (DVD) drives.

The coded instructions 1532 of FIG. 4 may be stored in the mass storage device 1528, in the volatile memory 1514, in the non-volatile memory 1516, and/or on a removable tangible computer readable storage medium such as a CD or DVD.

FIG. 16 is a block diagram of an example processor platform 1600 capable of executing the instructions of FIGS. 5-7 to implement the example STA communication converter 108 of FIGS. 1 and 3. The processor platform 1600 can be, for example, a server, a personal computer, a mobile device (e.g., a cell phone, a smart phone, a tablet such as an iPad™), a personal digital assistant (PDA), an Internet appliance, or any other type of computing device. The processor platform 1600 of the illustrated example includes a processor 1612. The processor 1612 of the illustrated example is hardware. For example, the processor 1612 can be implemented by integrated circuits, logic circuits, microprocessors or controllers from any desired family or manufacturer.

The processor 1612 of the illustrated example includes a local memory 1613 (e.g., a cache). The example processor 1612 of FIG. 16 executes the instructions of FIGS. 5-7 to implement the example receiver 300, the example PHY processor 302, the example trigger frame processor 304, the example UL/DL converter 306, the example interference determiner 308, and/or the example transmitter 310 of FIG. 3. The processor 1612 of the illustrated example is in communication with a main memory including a volatile memory 1614 and a non-volatile memory 1616 via a bus 1618. The volatile memory 1614 may be implemented by Synchronous Dynamic Random Access Memory (SDRAM), Dynamic Random Access Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM) and/or any other type of random access memory device. The non-volatile memory 1616 may be implemented by flash memory and/or any other desired type of memory device. Access to the main memory 1614, 1616 is controlled by a clock controller.

The processor platform 1600 of the illustrated example also includes an interface circuit 1620. The interface circuit 1620 may be implemented by any type of interface standard, such as an Ethernet interface, a universal serial bus (USB), and/or a PCI express interface.

In the illustrated example, one or more input devices 1622 are connected to the interface circuit 1620. The input device(s) 1622 permit(s) a user to enter data and commands into the processor 1612. The input device(s) can be implemented by, for example, a sensor, a microphone, a camera (still or video), a keyboard, a button, a mouse, a touchscreen, a track-pad, a trackball, isopoint and/or a voice recognition system.

One or more output devices 1624 are also connected to the interface circuit 1620 of the illustrated example. The output devices 1624 can be implemented, for example, by display devices (e.g., a light emitting diode (LED), an organic light emitting diode (OLED), a liquid crystal display, a cathode ray tube display (CRT), a touchscreen, a tactile output device, and/or speakers). The interface circuit 1620 of the illustrated example, thus, typically includes a graphics driver card, a graphics driver chip or a graphics driver processor. The interface circuit 1620 of the illustrated example also includes a communication device such as a transmitter, a receiver, a transceiver, a modem and/or network interface card to facilitate exchange of data with external machines (e.g., computing devices of any kind) via a network 1626 (e.g., an Ethernet connection, a digital subscriber line (DSL), a telephone line, coaxial cable, a cellular telephone system, etc.).

The processor platform 1600 of the illustrated example also includes one or more mass storage devices 1628 for storing software and/or data. Examples of such mass storage devices 1628 include floppy disk drives, hard drive disks, compact disk drives, Blu-ray disk drives, RAID systems, and digital versatile disk (DVD) drives.

The coded instructions 1632 of FIGS. 5-7 may be stored in the mass storage device 1628, in the volatile memory 1614, in the non-volatile memory 1616, and/or on a removable tangible computer readable storage medium such as a CD or DVD.

From the foregoing, it would be appreciated that the above disclosed method, apparatus, and articles of manufacture reduce co-channel interference in full-duplex Wi-Fi. To adjust full- duplex transmissions to reduce co-channel interference in subsequent transmissions, traditional techniques instruct a DL STA to measure the co-channel interference using additional overhead which may limit the full-duplex gain. For example, to schedule full-duplex UL and DL transmissions, a traditional AP may schedule interference measurement periods, during which the connected STAs measure interference levels from each other and report the measurements to the AP. In such an example, the AP uses the interference report to adjust subsequent full-duplex UL and DL communications to reduce the co-channel interference. However, such traditional techniques are done at the cost of additional overhead. Additionally, the frequent scheduling of interference measurement periods limit the full-duplex gain. Additionally, traditional techniques to adjust subsequent transmissions to reduce co-channel interference and are not able to reduce co-channel interference on the pilot tones.

Examples disclosed herein facilitate full duplex Wi-Fi communications using a pilot tone pattern that reduces and/or measure co-channel interference on both the data tones and the pilot tones. In some examples, the pilot tone pattern includes a UL pattern and a DL pattern to ensure that there is no overlap between UL and DL transmissions on OFDM sub-carriers to reduce co- channel interference on the pilot tones. In some examples, a DL STA leverages the OFDM sub- carriers being used for UL but are idle for DL to measure co-channel interference caused by the UL transmission to reduce co-channel interference on the data tones. In this manner, the AP can adjust subsequent full-duplex transmissions without the overhead of traditional techniques.

Example 1 is an apparatus to reduce co-channel interference in a wireless network.

Example 1 includes a receiver to receive a pilot tone pattern corresponding to a reservation of a first pilot sub-carrier for at least one of uplink or downlink transmission. Example 1 further includes an uplink/downlink converter to: when the first pilot sub-carrier is reserved for uplink transmission during a full-duplex transmission, refrain from receiving a downlink packet; and when the first pilot sub-carrier is not reserved for uplink transmission, receive a downlink packet.

Example 2 includes the subject matter of Example 1, wherein the pilot tone pattern is received in a trigger frame from an access point.

Example 3 includes the subject matter of Example 2, further including a trigger frame processor to process the trigger frame to determine the pilot tone pattern.

Example 4 includes the subject matter of Examples 1-3, wherein the pilot tone pattern includes a first reservation of the first pilot sub-carrier for uplink transmission at a first time of the full-duplex transmission and a second reservation of the first pilot sub-carrier for downlink transmission at a second time of the full-duplex transmission.

Example 5 includes the subject matter of Examples 1-3, further including an interference determiner to, when the first pilot sub-carrier is reserved for the uplink transmission, measure a co-channel interference caused by the uplink transmission.

Example 6 includes the subject matter of Example 5, further including a transmitter to transmit the measured co-channel interference to an access point.

Example 7 is an apparatus to reduce co-channel interference in a wireless network.

Example 7 includes a pilot tone determiner to determine a pilot tone protocol corresponding to a pilot tone pattern, the pilot tone pattern corresponding to a reservation of (A) a pilot sub-carrier at a first time for uplink transmission and (B) the pilot sub-carrier at a second time for downlink transmission; and determine if a first station and a second station are capable of operating using the pilot tone protocol. Example 7 further includes a transmitter to transmit the pilot tone pattern to the first and second stations.

Example 8 includes the subject matter of Example 7, wherein the transmitter is to refrain from transmitting a downlink packet using the pilot sub-carrier to the second station at the first time; and transmit a downlink packet using the pilot sub-carrier to the second station at the second time.

Example 9 includes the subject matter of Example 8, further including a receiver to receive an uplink packet from the first station using the pilot sub-carrier at the first time.

Example 10 includes the subject matter of Example 7, wherein the pilot tone pattern corresponds to a second reservation of (A) a second pilot sub-carrier at the first time for uplink transmission and (B) the second pilot sub-carrier at the second time for downlink transmission.

Example 11 includes the subject matter of Example 7, wherein the pilot tone pattern corresponds to a second reservation of (A) a second pilot sub-carrier at the first time for downlink transmission and (B) the second pilot sub-carrier at the second time for uplink transmission.

Example 12 includes the subject matter of Examples 10 or 11, wherein the pilot tone pattern corresponds to a third reservation of (A) a third pilot sub-carrier at a third time for uplink transmission and (B) the third pilot sub-carrier at a fourth time for downlink transmission.

Example 13 includes the subject matter of Examples 10 or 11, wherein the pilot tone pattern corresponds to a third reservation of (A) a third pilot sub-carrier at a third time for uplink transmission and (B) a fourth pilot sub-carrier at the third time for downlink transmission.

Example 14 includes the subject matter of Examples 7-9, further including a receiver to receive a co-channel interference from the second station, the co-channel interference being measured by the second station using the pilot sub-carrier at the first time caused by a transmission of an uplink packet from the first station.

Example 15 includes the subject matter of Example 14, further including a future scheduling adjuster to adjust subsequent transmissions based on the co-channel interference.

Example 16 includes the subject matter of Examples 7-9, wherein the pilot tone determiner is to verify an ability to communicate using the pilot tone protocol using a physical layer.

Example 17 includes the subject matter of Examples 7-9, wherein the transmitter is to transmit the pilot tone pattern to the first and second stations in a trigger frame.

Example 18 is a method to reduce co-channel interference in a wireless network.

Example 17 includes receiving a pilot tone pattern corresponding to a reservation of a first pilot sub-carrier for at least one of uplink or downlink transmission. Example 18 further includes, when the first pilot sub-carrier is reserved for uplink transmission during a full-duplex transmission, refraining from receiving a downlink packet. Example 18 further includes, when the first pilot sub-carrier is not reserved for uplink transmission, receiving a downlink packet.

Example 19 includes the subject matter of Example 18, wherein the pilot tone pattern is received in a trigger frame from an access point.

Example 20 includes the subject matter of Example 19, further including processing the trigger frame to determine the pilot tone pattern.

Example 21 includes the subject matter of Examples 18-20, wherein the pilot tone pattern includes a first reservation of the first pilot sub-carrier for uplink transmission at a first time of the full-duplex transmission and a second reservation of the first pilot sub-carrier for downlink transmission at a second time of the full-duplex transmission.

Example 22 includes the subject matter of Examples 18-20, further including, when the first pilot sub-carrier is reserved for the uplink transmission, measuring a co-channel interference caused by the uplink transmission.

Example 23 includes the subject matter of Example 22, further including transmitting the measured co-channel interference to an access point.

Example 24 is a method to reduce co-channel interference in a wireless network.

Example 24 includes determining a pilot tone protocol corresponding to a pilot tone pattern, the pilot tone pattern corresponding to a reservation of (A) a pilot sub-carrier at a first time for uplink transmission and (B) the pilot sub-carrier at a second time for downlink transmission. Example 24 further includes determining if a first station and a second station are capable of operating using the pilot tone protocol. Example 24 further includes transmitting the pilot tone pattern to the first and second stations.

Example 25 includes the subject matter of Example 24, further including refraining from transmitting a downlink packet using the pilot sub-carrier to the second station at the first time; and transmitting a downlink packet using the pilot sub-carrier to the second station at the second time.

Example 26 includes the subject matter of Example 25, further including receiving an uplink packet from the first station using the pilot sub-carrier at the first time. Example 27 includes the subject matter of Example 24, wherein the pilot tone pattern corresponds to a second reservation of (A) a second pilot sub-carrier at the first time for uplink transmission and (B) the second pilot sub-carrier at the second time for downlink transmission.

Example 28 includes the subject matter of Example 24, wherein the pilot tone pattern corresponds to a second reservation of (A) a second pilot sub-carrier at the first time for downlink transmission and (B) the second pilot sub-carrier at the second time for uplink transmission.

Example 29 includes the subject matter of Examples 27 or 28, wherein the pilot tone pattern corresponds to a third reservation of (A) a third pilot sub-carrier at a third time for uplink transmission and (B) the third pilot sub-carrier at a fourth time for downlink transmission.

Example 30 includes the subject matter of Examples 27 or 28, wherein the pilot tone pattern corresponds to a third reservation of (A) a third pilot sub-carrier at a third time for uplink transmission and (B) a fourth pilot sub-carrier at the third time for downlink transmission.

Example 31 includes the subject matter of Examples 24-26, further including receiving a co-channel interference from the second station, the co-channel interference being measured by the second station using the pilot sub-carrier at the first time caused by a transmission of an uplink packet from the first station.

Example 32 includes the subject matter of Example 31, further including adjusting subsequent transmissions based on the co-channel interference.

Example 33 includes the subject matter of Examples 24-26, further including verifying an ability to communicate using the pilot tone protocol using a physical layer.

Example 34 includes the subject matter of Examples 24-26, further including transmitting the pilot tone pattern to the first and second stations in a trigger frame.

Example 35 is a tangible computer readable storage medium comprising instructions which, when executed, cause a machine to at least: receive a pilot tone pattern corresponding to a reservation of a first pilot sub-carrier for at least one of uplink or downlink transmission; when the first pilot sub-carrier is reserved for uplink transmission during a full-duplex transmission, refrain from receiving a downlink packet; and when the first pilot sub-carrier is not reserved for uplink transmission, receive a downlink packet.

Example 36 includes the subject matter of Example 35, wherein the pilot tone pattern is received in a trigger frame from an access point. Example 37 includes the subject matter of Example 36, further including instructions to cause the machine to process the trigger frame to determine the pilot tone pattern.

Example 38 includes the subject matter of Examples 35-37, wherein the pilot tone pattern includes a first reservation of the first pilot sub-carrier for uplink transmission at a first time of the full-duplex transmission and a second reservation of the first pilot sub-carrier for downlink transmission at a second time of the full-duplex transmission.

Example 39 includes the subject matter of Examples 35-37, further including instructions to cause the machine to, when the first pilot sub-carrier is reserved for the uplink transmission, measure a co-channel interference caused by the uplink transmission.

Example 40 includes the subject matter of Example 39, further including instructions to cause the machine to transmit the measured co-channel interference to an access point.

Example 41 is a tangible computer readable storage medium comprising instructions which, when executed, cause a machine to at least: determine a pilot tone protocol corresponding to a pilot tone pattern, the pilot tone pattern corresponding to a reservation of (A) a pilot sub- carrier at a first time for uplink transmission and (B) the pilot sub-carrier at a second time for downlink transmission; determine if a first station and a second station are capable of operating using the pilot tone protocol; and transmit the pilot tone pattern to the first and second stations.

Example 42 includes the subject matter of Example 41, wherein the instructions cause the machine to: refrain from transmitting a downlink packet using the pilot sub-carrier to the second station at the first time; and transmit a downlink packet using the pilot sub-carrier to the second station at the second time.

Example 43 includes the subject matter of Example 42, wherein the instructions cause the machine to receive an uplink packet from the first station using the pilot sub-carrier at the first time.

Example 44 includes the subject matter of Example 41, wherein the pilot tone pattern corresponds to a second reservation of (A) a second pilot sub-carrier at the first time for uplink transmission and (B) the second pilot sub-carrier at the second time for downlink transmission.

Example 45 includes the subject matter of Example 41, wherein the pilot tone pattern corresponds to a second reservation of (A) a second pilot sub-carrier at the first time for downlink transmission and (B) the second pilot sub-carrier at the second time for uplink transmission. Example 46 includes the subject matter of Examples 44 or 45, wherein the pilot tone pattern corresponds to a third reservation of (A) a third pilot sub-carrier at a third time for uplink transmission and (B) the third pilot sub-carrier at a fourth time for downlink transmission.

Example 47 includes the subject matter of Examples 44 or 45, wherein the pilot tone pattern corresponds to a third reservation of (A) a third pilot sub-carrier at a third time for uplink transmission and (B) a fourth pilot sub-carrier at the third time for downlink transmission.

Example 48 includes the subject matter of Examples 41-43, wherein the instructions cause the machine to receive a co-channel interference from the second station, the co-channel interference being measured by the second station using the pilot sub-carrier at the first time caused by a transmission of an uplink packet from the first station.

Example 49 includes the subject matter of Example 48, wherein the instructions cause the machine to adjust subsequent transmissions based on the co-channel interference.

Example 50 includes the subject matter of Examples 41-43, wherein the instructions cause the machine to verify an ability to communicate using the pilot tone protocol using a physical layer.

Example 51 includes the subject matter of Examples 41-43, wherein the instructions cause the machine to transmit the pilot tone pattern to the first and second stations in a trigger frame.

Example 52 is an apparatus to reduce co-channel interference in a wireless network. Example 52 includes a first means for receiving a pilot tone pattern corresponding to a reservation of a first pilot sub-carrier for at least one of uplink or downlink transmission.

Example 52 further includes a second means for: when the first pilot sub-carrier is reserved for uplink transmission during a full-duplex transmission, refraining from receiving a downlink packet; and when the first pilot sub-carrier is not reserved for uplink transmission, receiving a downlink packet.

Example 53 includes the subject matter of Example 52, wherein the pilot tone pattern is received in a trigger frame from an access point.

Example 54 includes the subject matter of Example 53, further including a third means for processing the trigger frame to determine the pilot tone pattern.

Example 55 includes the subject matter of Examples 52-54, wherein the pilot tone pattern includes a first reservation of the first pilot sub-carrier for uplink transmission at a first time of the full-duplex transmission and a second reservation of the first pilot sub-carrier for downlink transmission at a second time of the full-duplex transmission.

Example 56 includes the subject matter of Examples 52-54, further including a fourth means for, when the first pilot sub-carrier is reserved for the uplink transmission, measuring a co-channel interference caused by the uplink transmission.

Example 57 includes the subject matter of Example 56, further including a fifth means for transmitting the measured co-channel interference to an access point.

Example 58 is an apparatus to reduce co-channel interference in a wireless network. Example 58 includes a first means for: determining a pilot tone protocol corresponding to a pilot tone pattern, the pilot tone pattern corresponding to a reservation of (A) a pilot sub-carrier at a first time for uplink transmission and (B) the pilot sub-carrier at a second time for downlink transmission; and determining if a first station and a second station are capable of operating using the pilot tone protocol. Example 58 further includes a second means for transmitting the pilot tone pattern to the first and second stations.

Example 59 includes the subject matter of Example 58, wherein the second means includes: means for refraining from transmitting a downlink packet using the pilot sub-carrier to the second station at the first time; and means for transmitting a downlink packet using the pilot sub-carrier to the second station at the second time.

Example 60 includes the subject matter of Example 59, further including third means for receiving an uplink packet from the first station using the pilot sub-carrier at the first time.

Example 61 includes the subject matter of Example 58, wherein the pilot tone pattern corresponds to a second reservation of (A) a second pilot sub-carrier at the first time for uplink transmission and (B) the second pilot sub-carrier at the second time for downlink transmission.

Example 62 includes the subject matter of Example 58, wherein the pilot tone pattern corresponds to a second reservation of (A) a second pilot sub-carrier at the first time for downlink transmission and (B) the second pilot sub-carrier at the second time for uplink transmission.

Example 63 includes the subject matter of Examples 61 or 62, wherein the pilot tone pattern corresponds to a third reservation of (A) a third pilot sub-carrier at a third time for uplink transmission and (B) the third pilot sub-carrier at a fourth time for downlink transmission. Example 64 includes the subject matter of Examples 61 or 62, wherein the pilot tone pattern corresponds to a third reservation of (A) a third pilot sub-carrier at a third time for uplink transmission and (B) a fourth pilot sub-carrier at the third time for downlink transmission.

Example 65 includes the subject matter of Examples 58-60, further including a third means for receiving a co-channel interference from the second station, the co-channel interference being measured by the second station using the pilot sub-carrier at the first time caused by a transmission of an uplink packet from the first station.

Example 66 includes the subject matter of Example 65, further including a forth means for adjusting subsequent transmissions based on the co-channel interference.

Example 67 includes the subject matter of Examples 58-60, wherein the first means includes means for verifying an ability to communicate using the pilot tone protocol using a physical layer.

Example 68 includes the subject matter of Examples 58-60, wherein the second means includes means for transmitting the pilot tone pattern to the first and second stations in a trigger frame.

Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of coverage of this patent is not limited thereto. On the contrary, this patent covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims of this patent.

Claims

What Is Claimed Is:

1. An apparatus to reduce co-channel interference in a wireless network, the apparatus comprising:

a receiver to receive a pilot tone pattern corresponding to a reservation of a first pilot sub-carrier for at least one of uplink or downlink transmission; and

an uplink/downlink converter to:

when the first pilot sub-carrier is reserved for uplink transmission during a full- duplex transmission, refrain from receiving a downlink packet; and

when the first pilot sub-carrier is not reserved for uplink transmission, receive a downlink packet.

2. The apparatus of claim 1, wherein the pilot tone pattern is received in a trigger frame from an access point.

3. The apparatus of claim 2, further including a trigger frame processor to process the trigger frame to determine the pilot tone pattern.

4. The apparatus of claims 1-3, wherein the pilot tone pattern includes a first reservation of the first pilot sub-carrier for uplink transmission at a first time of the full-duplex transmission and a second reservation of the first pilot sub-carrier for downlink transmission at a second time of the full-duplex transmission.

5. The apparatus of claims 1-3, further including an interference determiner to, when the first pilot sub-carrier is reserved for the uplink transmission, measure a co-channel interference caused by the uplink transmission.

6. The apparatus of claim 5, further including a transmitter to transmit the measured co-channel interference to an access point.

7. An apparatus to reduce co-channel interference in a wireless network, the apparatus comprising:

a pilot tone determiner to:

determine a pilot tone protocol corresponding to a pilot tone pattern, the pilot tone pattern corresponding to a reservation of (A) a pilot sub-carrier at a first time for uplink transmission and (B) the pilot sub-carrier at a second time for downlink transmission; and determine if a first station and a second station are capable of operating using the pilot tone protocol; and

a transmitter to transmit the pilot tone pattern to the first and second stations.

8. The apparatus of claim 7, wherein the transmitter is to:

refrain from transmitting a downlink packet using the pilot sub-carrier to the second station at the first time; and

transmit a downlink packet using the pilot sub-carrier to the second station at the second time.

9. The apparatus of claim 8, further including a receiver to receive an uplink packet from the first station using the pilot sub-carrier at the first time.

10. The apparatus of claim 7, wherein the pilot tone pattern corresponds to a second reservation of (A) a second pilot sub-carrier at the first time for uplink transmission and (B) the second pilot sub-carrier at the second time for downlink transmission.

11. The apparatus of claim 7, wherein the pilot tone pattern corresponds to a second reservation of (A) a second pilot sub-carrier at the first time for downlink transmission and (B) the second pilot sub-carrier at the second time for uplink transmission.

12. The apparatus of claims 10 or 11, wherein the pilot tone pattern corresponds to a third reservation of (A) a third pilot sub-carrier at a third time for uplink transmission and (B) the third pilot sub-carrier at a fourth time for downlink transmission.

13. The apparatus of claims 10 or 11, wherein the pilot tone pattern corresponds to a third reservation of (A) a third pilot sub-carrier at a third time for uplink transmission and (B) a fourth pilot sub-carrier at the third time for downlink transmission.

14. The apparatus of claims 7-9, further including a receiver to receive a co-channel interference from the second station, the co-channel interference being measured by the second station using the pilot sub-carrier at the first time caused by a transmission of an uplink packet from the first station.

15. The apparatus of claim 14, further including a future scheduling adjuster to adjust subsequent transmissions based on the co-channel interference.

16. The apparatus of claims 7-9, wherein the pilot tone determiner is to verify an ability to communicate using the pilot tone protocol using a physical layer.

17. The apparatus of claims 7-9, wherein the transmitter is to transmit the pilot tone pattern to the first and second stations in a trigger frame.

18. A method to reduce co-channel interference in a wireless network, the method comprising:

receiving a pilot tone pattern corresponding to a reservation of a first pilot sub-carrier for at least one of uplink or downlink transmission;

when the first pilot sub-carrier is reserved for uplink transmission during a full-duplex transmission, refraining from receiving a downlink packet; and

when the first pilot sub-carrier is not reserved for uplink transmission, receiving a downlink packet.

19. The method of claim 18, wherein the pilot tone pattern is received in a trigger frame from an access point.

20. A method to reduce co-channel interference in a wireless network, the method comprising:

determining a pilot tone protocol corresponding to a pilot tone pattern, the pilot tone pattern corresponding to a reservation of (A) a pilot sub-carrier at a first time for uplink transmission and (B) the pilot sub-carrier at a second time for downlink transmission;

determining if a first station and a second station are capable of operating using the pilot tone protocol; and

transmitting the pilot tone pattern to the first and second stations.

21. The method of claim 20, further including:

refraining from transmitting a downlink packet using the pilot sub-carrier to the second station at the first time; and

transmitting a downlink packet using the pilot sub-carrier to the second station at the second time.

22. A tangible computer readable storage medium comprising instructions which, when executed, cause a machine to at least:

receive a pilot tone pattern corresponding to a reservation of a first pilot sub-carrier for at least one of uplink or downlink transmission;

when the first pilot sub-carrier is reserved for uplink transmission during a full-duplex transmission, refrain from receiving a downlink packet; and when the first pilot sub-carrier is not reserved for uplink transmission, receive a downlink packet.

23. The computer readable storage medium of claim 22, wherein the pilot tone pattern is received in a trigger frame from an access point.

24. A tangible computer readable storage medium comprising instructions which, when executed, cause a machine to at least:

determine a pilot tone protocol corresponding to a pilot tone pattern, the pilot tone pattern corresponding to a reservation of (A) a pilot sub-carrier at a first time for uplink transmission and (B) the pilot sub-carrier at a second time for downlink transmission;

determine if a first station and a second station are capable of operating using the pilot tone protocol; and

transmit the pilot tone pattern to the first and second stations.

25. The computer readable storage medium of claim 24, wherein the instructions cause the machine to: