Method and system for nulling in a wireless communication network

Abstract

To provide a method and a system for nulling in a wireless communication network.SOLUTION: In a method and a system for nulling in a wireless communication network, a method implemented by a first wireless communication node for initiating nulling transmission includes the steps of transmitting a control message to be received by a second wireless communication node, and the control message informs the second wireless communication node of initiating nulling transmission towards a first station, and transmitting data to the first station during transmission of the nulling transmission from the second wireless communication node to the first station.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates generally to wireless communications, and more particularly to methods and systems for inter-cell interference nulling in wireless communication networks. [Background technology]

[0002] Rapid growth in user data has led to increasing demands on spectrum. Previous solutions to address existing and emerging user data traffic demands have increased data rates by widening frequency channels or densifying base station (BS) deployments. For example, channel bandwidths have increased from 200 kHz in the 2G Global System for Mobile Communications (GSM), to 5 MHz in 3G Wideband Code Division Multiple Access (WCDMA), to 20 MHz in 4G Long Term Evolution (LTE), and to 100 MHz in LTE-Advanced Pro. However, traditional sub-6 GHz frequency spectrum is almost fully allocated, making it expensive for system operators to obtain licenses. Furthermore, further network densification is limited by the cost and time required to obtain backhaul connections and installation permits in millions of local jurisdictions. Furthermore, even perfect reuse of frequency resources across adjacent cells leads to high levels of inter-cell interference, which in turn significantly limits the available communication speeds for some users, especially at cell edges.

[0003] For wireless local area networks, the same challenges as cellular wireless networks exist. For example, dense deployment of access points (APs) in many stores, apartment buildings, or shopping malls leads to overlapping basic service sets (BSSs), thereby reducing the performance of each network. Existing solutions address the problem of overlapping BSSs or inter-cell interference in wireless local area networks by using different orthogonal channels on each AP. However, this solution becomes impractical when the number of APs exceeds the number of available orthogonal channels.

[0004] Reuse of frequency resources across adjacent cells can increase the capacity of wireless network designs. However, systems and methods for inter-cell interference management are needed. In particular, systems and methods for inter-cell interference nulling between adjacent cells are needed. Summary of the Invention [Means for solving the problem]

[0005] The exemplary embodiments disclosed herein are directed to solving one or more of the problems posed by the prior art and to providing additional features that will become readily apparent by reference to the following detailed description when taken in conjunction with the accompanying drawings. According to various embodiments, exemplary systems, methods, devices, and computer program products are disclosed herein. It should be understood, however, that these embodiments are presented by way of example, and not limitation, and that various modifications to the disclosed embodiments may be made while remaining within the scope of the present disclosure, as will become apparent to those skilled in the art upon perusal of this disclosure.

[0006] In one embodiment, a method performed by a first wireless communication node for initiating a nulling transmission includes transmitting a control message to be received by a second wireless communication node, the control message informing the second wireless communication node of the initiation of a nulling transmission towards the first station, and transmitting data to the first station during transmission of the nulling transmission from the second wireless communication node to the first station.

[0007] In another embodiment, a method performed by a first wireless communication node for providing a nulling transmission includes receiving a control message from a second wireless communication node, the control message informing the first wireless communication node to initiate a nulling transmission toward the first station, and transmitting data to the second station during transmission of the nulling transmission from the first wireless communication node to the first station.

[0008] In a further embodiment, an apparatus for initiating a nulling transmission includes a transceiver configured to transmit a control message to be received by a wireless communication node, the control message informing the wireless communication node to initiate a nulling transmission toward a first station, and transmitting data to the first station during transmission of the nulling transmission from the wireless communication node to the first station.

[0009] In yet a further embodiment, an apparatus for initiating a nulling transmission includes a receiver configured to receive a control message from a wireless communication node, at least one processor configured to control an antenna to direct the nulling transmission directly toward the first station based on the received control message, and a transmitter configured to transmit data to a second station while transmitting the nulling transmission to the first station.

[0010] In a further embodiment, the present invention provides a non-transitory computer-readable storage medium storing computer-executable instructions that, when executed, perform any one of the methods disclosed herein.

[0011] In still a further embodiment, a wireless communication node includes a memory that stores computer-executable instructions that, when executed, perform any one of the methods disclosed herein; and at least one processor coupled to the memory and configured to execute the computer-executable instructions. For example, the present application provides the following: (Item 1) 1. A method implemented by a first wireless communication node for initiating a nulling transmission, the method comprising: transmitting a control message to be received by a second wireless communication node, the control message informing the second wireless communication node to initiate the nulling transmission towards the first station; transmitting data to the first station during transmission of the nulling transmission from the second wireless communication node to the first station; A method comprising: (Item 2) transmitting the data to the first station is initiated after a predetermined period of time has elapsed; the control message causes the second wireless communication node to start the nulling transmission after the predetermined period has elapsed; The method according to item 1. (Item 3) Item 2. The method according to item 1, wherein the control message causes the second wireless communication node to initiate a channel contention procedure and transmit the nulling transmission after successfully completing the channel contention procedure. (Item 4) receiving a response message from the second wireless communication node after transmitting the control message, wherein the predetermined period is determined based on a reception time of the response message; The nulling transmission is initiated after the predetermined period has elapsed. The method described in item 2. (Item 5) a first duration of transmission from the first wireless communication node is included in the control message; a second duration of transmission from the second wireless communication node is included in the response message; a duration of the nulling transmission is selected to be longer than those of the first and second durations; The method according to item 4. (Item 6) Item 10. The method of item 1, further comprising transmitting the control message to the first station to be relayed by the first station to the second wireless communication node. (Item 7) 2. The method of claim 1, wherein the control message is contained in a transmission containing the data transmitted to the first station. (Item 8) transmitting the control message to the first station to cause the first station to transmit a response message to be received by the second wireless communication node; the response message causing the second wireless communications node to select a second station based on at least one predetermined criterion; a nulling operation is performed on data transmission from the second wireless communication node to the second station; The method according to item 1. (Item 9) 9. The method of claim 8, wherein the at least one predetermined criterion comprises whether a strength of a residual signal received by the first station as a result of the data transmission from the second wireless communication node to the second station is less than or equal to a predetermined threshold value. (Item 10) Item 10. The method of claim 1, wherein the control message is received by a third wireless communication node, and the control message causes the second and third wireless communication nodes to initiate a channel contention procedure, and once a nulling transmission from either the second or third wireless communication node is detected, the other wireless communication node suspends its channel contention procedure until the nulling transmission is no longer detected. (Item 11) Item 11. The method of item 10, wherein the control message contains information identifying the second and third wireless communication nodes. (Item 12) Item 2. The method of item 1, wherein the control message contains information identifying the second wireless communication node. (Item 13) 1. A method implemented by a first wireless communication node for providing nulling transmission, the method comprising: receiving a control message from a second wireless communication node, the control message informing the first wireless communication node to initiate the nulling transmission towards the first station; transmitting data to a second station during transmission of said nulling transmission to said first station; A method comprising: (Item 14) transmitting the data to the second station is initiated after a predetermined period of time has elapsed; the control message causes the first wireless communication node to start the nulling transmission after the predetermined period has elapsed; Item 14. The method according to item 13. (Item 15) Item 14. The method according to item 13, wherein the control message causes the first wireless communication node to initiate a channel contention procedure and transmit the nulling transmission after successfully completing the channel contention procedure. (Item 16) transmitting a response message from the first wireless communication node after receiving the control message, wherein the predetermined period is determined based on a time for transmitting the response message; The nulling transmission is initiated after the predetermined period has elapsed. Item 14. The method according to item 13. (Item 17) a first duration of transmission from the first wireless communication node is included in the response message; a second duration of transmission from the second wireless communication node is included in the control message; a duration of the nulling transmission is selected to be longer than those of the first and second durations; Item 17. The method according to item 16. (Item 18) Item 14. The method of item 13, further comprising receiving the control message relayed by the first station to the first wireless communication node. (Item 19) Item 14. The method of item 13, wherein the control message is contained in a transmission containing the data transmitted to the first station. (Item 20) receiving a response message transmitted from the first station, the response message being transmitted in response to receiving the control message from the second wireless node; the received response message causes the first wireless communication node to select a second station based on at least one predetermined criterion; a nulling operation is performed on data transmission from the first wireless communication node to the second station; Item 14. The method according to item 13. (Item 21) 21. The method of claim 20, wherein the at least one predetermined criterion comprises whether a strength of a residual signal received by the first station as a result of a data transmission from the first wireless communication node to the second station is less than or equal to a predetermined threshold value. (Item 22) Item 14. The method of item 13, wherein the control message is received by a third wireless communication node, and the control message causes the first and third wireless communication nodes to start a channel contention procedure, and once a nulling transmission from either the first or third wireless communication node is detected, the other wireless communication node suspends its channel contention procedure until the nulling transmission is no longer detected. (Item 23) 23. The method of claim 22, wherein the control message contains information identifying the first and third wireless communication nodes. (Item 24) Item 14. The method of item 13, wherein the control message contains information identifying the first wireless communication node. (Item 25) a first wireless communication node, A transceiver, transmitting a control message to be received by a second wireless communication node, the control message informing the second wireless communication node to initiate a nulling transmission towards the first station; transmitting data to the first station during transmission of the nulling transmission from the second wireless communication node to the first station; a transceiver configured to: a first wireless communication node comprising: (Item 26) 26. The first wireless communication node according to item 25, wherein the transceiver is further configured to transmit the data to the first station after a predetermined period of time has elapsed. (Item 27) 26. The first wireless communication node of item 25, wherein the transmitted control message causes the second wireless communication node to start a channel contention procedure and transmit the nulling transmission after successfully completing the channel contention procedure. (Item 28) The transceiver further comprises: 26. The first wireless communication node according to item 25, configured to receive a response message from the second wireless communication node after transmitting the control message, wherein the predetermined period is determined based on the reception time of the response message. (Item 29) a first duration of transmission from the first wireless communication node is included in the control message; a second duration of transmission from the second wireless communication node is included in the response message; a duration of the nulling transmission is selected to be longer than those of the first and second durations; Item 29. The first wireless communication node according to item 28. (Item 30) 26. The first wireless communication node according to item 25, further configured to transmit the control message to the first station to be relayed by the first station to the second wireless communication node. (Item 31) 26. The first wireless communication node according to item 25, wherein the control message is contained in a transmission containing the data transmitted to the first station. (Item 32) further configured to transmit the control message to the first station to cause the first station to transmit a response message to be received by the second wireless communication node; the response message causing the second wireless communication node to select a second station based on at least one predetermined criterion; a nulling operation is performed on data transmission from the second wireless communication node to the second station; Item 26. The first wireless communication node according to item 25. (Item 33) 33. The first wireless communication node of claim 32, wherein the at least one predetermined criterion comprises whether the strength of a residual signal received by the first station as a result of the data transmission from the second wireless communication node to the second station is less than or equal to a predetermined threshold value. (Item 34) 26. The first wireless communication node of claim 25, wherein the control message is received by a third wireless communication node, and the control message causes the second and third wireless communication nodes to initiate a channel contention procedure, and once a nulling transmission from either the second or third wireless communication node is detected, the other wireless communication node suspends its channel contention procedure until the nulling transmission is no longer detected. (Item 35) Item 35. The first wireless communication node according to item 34, wherein the control message contains information identifying the second and third wireless communication nodes. (Item 36) 26. The first wireless communication node according to item 25, wherein the control message contains information identifying the second wireless communication node. (Item 37) a first wireless communication node, A transceiver, receiving a control message from a second wireless communication node, the control message informing the first wireless communication node to initiate the nulling transmission towards the first station; transmitting data to a second station during transmission of the nulling transmission from the first wireless communication node to the first station; a transceiver configured to: a first wireless communication node comprising: (Item 38) transmitting the data to the second station is initiated after a predetermined period of time has elapsed; the control message causes the first wireless communication node to start the nulling transmission after the predetermined period has elapsed; Item 38. The first wireless communication node according to item 37. (Item 39) The first wireless communication node described in item 37, wherein the control message causes the first wireless communication node to start a channel contention procedure and transmit the nulling transmission after successfully completing the channel contention procedure. (Item 40) further configured to transmit a response message from the first wireless communication node after receiving the control message, wherein the predetermined period is determined based on a time for transmitting the response message; The nulling transmission is initiated after the predetermined period has elapsed. Item 39. The first wireless communication node according to item 39. (Item 41) a first duration of transmission from the first wireless communication node is included in the response message; a second duration of transmission from the second wireless communication node is included in the control message; a duration of the nulling transmission is selected to be longer than those of the first and second durations; Item 41. A first wireless communication node according to item 40. (Item 42) Item 38. The first wireless communication node according to item 37, further configured to receive the control message relayed by the first station to the first wireless communication node. (Item 43) Item 38. The first wireless communication node according to item 37, wherein the control message is contained in a transmission containing the data transmitted to the first station. (Item 44) further configured to receive a response message transmitted from the first station, the response message being transmitted in response to receiving the control message from the second wireless node; the received response message causes the first wireless communications node to select a second station based on at least one predetermined criterion; a nulling operation is performed on data transmission from the first wireless communication node to the second station; Item 38. The first wireless communication node according to item 37. (Item 45) Item 45. The first wireless communication node of item 44, wherein the at least one predetermined criterion comprises whether the strength of a residual signal received by the first station as a result of data transmission from the first wireless communication node to the second station is less than or equal to a predetermined threshold value. (Item 46) The first wireless communication node described in item 37, wherein the control message is received by a third wireless communication node, and the control message causes the first and third wireless communication nodes to start a channel contention procedure, and once a nulling transmission from either the first or third wireless communication node is detected, the other wireless communication node suspends its channel contention procedure until the nulling transmission is no longer detected. (Item 47) Item 47. The first wireless communication node according to item 46, wherein the control message contains information identifying the second and third wireless communication nodes. (Item 48) Item 38. The first wireless communication node according to item 37, wherein the control message contains information identifying the second wireless communication node. (Item 49) 25. A non-transitory computer-readable storage medium having computer-executable instructions stored thereon, the computer-executable instructions, when executed, performing any one of the methods of items 1-24. [Brief explanation of the drawings]

[0012] Various exemplary embodiments of the present disclosure are described in detail below with reference to the following figures. The drawings are provided for illustrative purposes only and merely depict exemplary embodiments of the present disclosure to facilitate the reader's understanding of the present disclosure. Therefore, the drawings should not be considered limiting of the scope, scope, or applicability of the present disclosure. It should be noted that for clarity and ease of illustration, the drawings are not necessarily drawn to scale.

[0013] [Figure 1] FIG. 1 illustrates a block diagram of an exemplary multi-cell communication network in which interference nulling techniques disclosed herein may be implemented, in accordance with some embodiments of the present invention.

[0014] [Figure 2A] FIG. 2A illustrates a timing diagram for transmitting a control message, a data transmission to a first station, and a data transmission with interference nulling to a second station in accordance with some embodiments of the present invention.

[0015] [Figure 2B] FIG. 2B illustrates a timing diagram for transmitting a control message, a channel contention window, a data transmission to a first station, and a data transmission with interference nulling to a second station in accordance with a further embodiment of the present invention.

[0016] [Figure 2C] FIG. 2C illustrates a timing diagram for transmitting a control message, a response message, a data transmission to a first station, and a data transmission with interference nulling to a second station in accordance with various embodiments of the present invention.

[0017] [Figure 3A] FIG. 3A illustrates a block diagram of an exemplary multi-cell communication network in which stations transmit or relay control messages to wireless communication nodes, in accordance with some embodiments of the present invention.

[0018] [Figure 3B] FIG. 3B illustrates a timing diagram for transmitting a first control message, a second control message, a data transmission to a first station, and a data transmission with interference nulling to a second station in accordance with a further embodiment of the present invention.

[0019] [Figure 4] FIG. 4 illustrates a timing diagram for a data transmission to a first station and a delayed data transmission with interference nulling to a second station in accordance with various embodiments of the present invention.

[0020] [Figure 5A] FIG. 5A illustrates a block diagram of an exemplary multi-cell communication network in which interference nulling techniques are implemented with a first station receiving a control message from a first communication node and transmitting response message data before receiving a data transmission, in accordance with some embodiments of the present invention.

[0021] [Figure 5B] FIG. 5B illustrates a timing diagram for transmitting a first control message, a second response message, a data transmission to a first station, and a data transmission with nulling to a second station in accordance with a further embodiment of the present invention.

[0022] [Figure 6] FIG. 6 illustrates a timing diagram for transmitting a first control message, a first channel contention window, a second channel contention window with a reserved backoff procedure, a third channel contention window with a reserved backoff procedure, a data transmission to a first station, and a data transmission with interference nulling to a second station in accordance with a further embodiment of the present invention.

[0023] [Figure 7]FIG. 7 illustrates a block diagram of a wireless communication node configured to perform the methods disclosed herein, according to various embodiments of the invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Various exemplary embodiments of the present disclosure are described below with reference to the accompanying drawings to enable those skilled in the art to make and use the present disclosure. As will be apparent to those skilled in the art, after reading this disclosure, various changes or modifications of the examples described herein can be made without departing from the scope of the present disclosure. Therefore, the present disclosure is not limited to the exemplary embodiments and applications described and illustrated herein. In addition, the specific order and / or hierarchy of steps in the methods disclosed herein is merely an example approach. Based on design preferences, the specific order or hierarchy of steps in a disclosed method or process can be rearranged while remaining within the present disclosure. Thus, those skilled in the art will understand that the methods and techniques disclosed herein present various steps or acts in a sample order, and that the present disclosure is not limited to the specific order or hierarchy presented, unless expressly stated otherwise.

[0025] As discussed herein, a "wireless communication node" may include or be implemented as an evolved Node B (gNB), an E-UTRAN Node B (eNB), a transmission / reception point (TRP), an access point (AP), a donor node (DN), a relay node, a core network (CN) node, a RAN node, a master node, a secondary node, a distributed unit (DU), a centralized unit (CU), etc., in accordance with the customary understanding of these terms in the art. Furthermore, as discussed herein, a "wireless communication device" may include or be implemented as a station (STA), a mobile terminal (MT), a mobile station (MS), etc., in accordance with the customary understanding of these terms in the art. In the description of the exemplary embodiments below, a "wireless communication node" will be referred to as an "AP," and a "wireless communication device" will be referred to as an "STA." However, it should be understood that the scope of the present disclosure is not limited to these exemplary embodiments.

[0026] FIG. 1 illustrates an exemplary communication network 100 in which the inter-cell interference nulling techniques disclosed herein may be implemented, in accordance with some embodiments of the present invention. As shown in FIG. 1, the exemplary multi-cell communication network 100 includes a master access point (MAP) 101, a neighbor access point (NAP) 104, and multiple STAs, e.g., a first STA 102 and a second STA 103, communicatively coupled to the MAP 101 and the NAP 104 via respective RF links 108, 109, 110, and 111. In some embodiments, the RF links 108, 109, 110, and 111 are unlicensed links. In various embodiments, the RF links 108, 109, 110, and 111 operate in a millimeter-wave radio frequency band, such as the 60 GHz unlicensed band. FIG. 1 also illustrates a wireless cell coverage 105 of the MAP 101 and a wireless cell coverage 106 of the NAP 104. In some embodiments, wireless cells 105 and 106 may have an overlapping coverage area 107, as shown in Figure 1. In further embodiments, STAs 102 and 103 may be co-located in the overlapping coverage area 107 near the cell edges of wireless cells 105 and 106. Accordingly, this disclosure describes systems and methods for providing inter-cell interference nulling for stations located in the overlapping coverage area 107, according to some embodiments.

[0027] According to various embodiments, the MAP 101 and NAP 104 may each be equipped with multiple antennas (e.g., antenna arrays) configured to provide a multiple-input, multiple-output (MIMO) link to the multiple STAs 102 and 103. As an alternative embodiment, the MAP 101 and NAP 104 may each be equipped with a phased array antenna capable of forming one or more beams of radio waves that can be electronically steered. In addition, the MAP 101 and NAP 104 are configured to transmit to the multiple STAs 102 and 103 using the same channel resources, such as frequency and time. While only two APs 101 and 104 and only two STAs 102 and 103 are shown in FIG. 1 , it should be understood that additional APs and additional STAs may be present in the wireless network to implement the inter-cell interference nulling techniques described herein according to various embodiments of the present invention.

[0028] Like the MAP 101 and the NAP 104, the STAs 102 and 103 may each include multiple antennas or phased antenna arrays. In an alternative embodiment, the STAs 102 and 103 may each be equipped with a single antenna. In the example shown in FIG. 1, the STAs 102 and 103 may be associated with the MAP 101 and the NAP 104. In one embodiment, the STAs 102 and 103 may be associated with the MAP 101 and the NAP 104 via a basic service set (BSS).

[0029] 1 , MAP 101 is configured to generate and transmit a data-transmission beam 108 to a first STA 102, and NAP 104 is configured to generate and transmit a data-transmission beam 109 to a second STA 103. MAP 101 is further configured to generate and transmit an interference-nulling beam 111 intended to null / minimize the power transmitted toward the second STA 103, and NAP 104 is further configured to generate and transmit an interference-nulling beam 110 intended to null / minimize the power transmitted toward the first STA 102. According to various embodiments, MAP 101 and NAP 104 may utilize any precoding scheme to form the interference-nulling beams 109 and 110. For example, MAP 101 and NAP 104 may utilize a linear precoding technique, such as a zero-forcing (ZF) beamforming method, to null out interference signals toward STAs 102 and 103. Such precoding enables the MAP 101 and NAP 104 to create antenna patterns that favor wave propagation along desired spatial directions while attenuating (nulling) propagation along undesired directions.

[0030] In some embodiments, the MAP 101 and the NAP 104 rely on estimated channel state information (CSI), which describes the channel properties of the RF link between the transmitter and receiver, to form data-transmission beams 108 and 109, respectively, and interference-nulling beams 110 and 111, respectively. As shown in FIG. 1 , the MAP 101 can simultaneously transmit the data-transmission beam 108 to the first STA 102 and the interference-nulling beam 111 to the second STA 103, according to some embodiments. Similarly, the NAP 104 can simultaneously transmit the data-transmission beam 109 to the second STA 103 and the interference-nulling beam 110 to the first STA 102, according to some embodiments. Furthermore, the channel state information (CSI) may indicate propagation conditions of the communication link from the transmitter to the receiver, such as, for example, scattering, fading, and the aggregate effects of power attenuation with distance.

[0031] Generally, a receiver can estimate the CS by a predetermined signal (such as a reference signal, training signal, or pilot signal) in a received radio frame. Therefore, the CSI enables a receiver to adapt transmission according to channel conditions so that higher network throughput and spectral efficiency can be achieved in a MIMO system. In some embodiments, the CSI may be utilized to calculate a precoding vector / matrix for beamforming to minimize signal energy at a target receiver. The CSI may also be used to determine whether interference to another target receiver in a neighboring network can be eliminated, according to some embodiments. In some embodiments, the CSI may be expressed in the form of a channel impulse response in the time domain or a channel frequency response in the frequency domain.

[0032] FIG. 2A illustrates a timing diagram for transmitting a wireless control message 201 from a master AP (e.g., MAP 101) to a neighboring AP (e.g., NAP 104), where the control message informs the neighboring AP that a nulling transmission 204 from the neighboring AP to a target station (e.g., first STA 102) is enabled. In some embodiments, the control message 201 is transmitted in a radio frame. In alternative embodiments, the control message 201 may be transmitted in any suitable data format (e.g., subframe, resource block (RB), etc.) having any suitable length / size for a given wireless network, system, or protocol. As shown in FIG. 2A , in some embodiments, the master AP initiates data transmission 203 to the target station after a predetermined amount of time 202 responsive to the completion of the transmission of the control message 201. In some embodiments, the radio frame carrying the wireless control message 201 may be an announcement or trigger frame. In some embodiments, the radio frame carrying the radio control message 201 may be a null packet, comprising only a preamble portion of a data packet. In some embodiments, the predetermined amount of time 202 may be one SIFS (e.g., 16 microseconds).

[0033] In some embodiments, the wireless control message 201 may include identification of one or more neighboring APs (e.g., NAP 104). For example, the wireless control message 201 may include a single ID, a group ID, a medium access control (MAC) address, a pair ID for one or more neighboring APs, two or more single IDs, multiple group IDs, multiple MAC addresses, or pair IDs for two or more neighboring APs that are authorized to transmit the nulling transmission 204 to one or more target STAs. In response to receiving the control message, the one or more neighboring APs are configured to transmit a data transmission to a separate STA (e.g., a second STA 103) that is different from the target STA (e.g., a first STA 102) using a nulling operation directed toward the target STA. In other words, each neighboring AP will transmit data to a separate intended STA while simultaneously transmitting a nulling transmission (i.e., an interfering nulling beam) to a separate target STA. The effect of the nulling transmission is to cancel the effect of any interference from the intended data transmission to the intended STA that may reach the target STA. In some embodiments, one or more neighboring APs may begin transmitting a data transmission using nulling operation 204 a predetermined period of time after receiving control message 201, such that the data transmission using nulling operation 204 may begin substantially simultaneously with the master AP beginning its data transmission 203 to the target STA.

[0034] Referring to FIG. 2B , in some embodiments, a master AP will transmit a control message (e.g., a radio frame) 211 and, after a predetermined period 212, will transmit a data transmission 213 to a target STA (e.g., the first STA 102). This is similar to the embodiment described above with respect to FIG. 2A . However, in this embodiment, after a neighboring AP receives the control message 211 from the master AP, the neighboring AP may initiate a channel contention protocol 214. The channel contention protocol 214 may be any mechanism used to share a given wireless channel among multiple APs that wish to simultaneously utilize the wireless channel. For example, the channel contention protocol 214 may be based on an enhanced distributed channel access (EDCA) or distributed channel function (DCF) mechanism. According to various other embodiments, when using the enhanced distributed channel access (EDCA) or distributed channel function (DCF) mechanism, a neighboring AP may be allowed to have higher priority for accessing the shared wireless channel than the station associated with it.

[0035] FIG. 2C illustrates a timing diagram for transmitting a control message, a response message, a data transmission to a first station, and a data transmission using interference nulling to a second station according to a further embodiment of the present invention. FIG. 2C is similar to FIG. 2A, however, in response to receiving the control message 221, the neighboring AP will transmit a response message 223. According to various embodiments, the response message 223 may be an acknowledgement (ACK) frame, a clear to send (CTS) control frame, or a NULL frame. In some embodiments, the master AP may initiate the data transmission 222 following a predetermined period after receiving the response message 223 from the neighboring AP. Similarly, the neighboring AP will begin transmitting a data transmission using nulling operation 224 following a predetermined period after completing the transmission of the response message 223. In some embodiments, both the master AP and the neighboring AP will begin their respective transmissions 222 and 224 at substantially the same time following the completion of the transmission of the response message 223.

[0036] Additionally, a response message 223 may be transmitted by a neighboring AP to occupy the wireless channel prior to transmitting a data transmission using the nulling operation 224. In this case, a channel contention procedure with other neighboring APs may not be necessary because, in response to detecting the response message transmitted by the first neighboring AP, the other neighboring AP may be preconfigured to continue its individual channel contention procedure for a predetermined period of time. In some embodiments, the response message 223 may include information related to the time duration, and the shared wireless channel may be occupied by the neighboring AP while the other neighboring AP may perform a data transmission using the nulling operation 224. Thus, the other neighboring AP may continue its individual channel contention procedure for the indicated duration for performing a data transmission using the nulling operation 224. As discussed above, a data transmission using the nulling operation 224 comprises a data transmission to an intended STA (e.g., the second STA 103) while simultaneously transmitting an interference-canceling “nulling transmission” to a target STA (e.g., the first STA 102).

[0037] In further embodiments, information about the duration or length of a data transmission from the master AP or a neighboring AP can be included in the wireless control message 221 and / or the response message 223. In cases of non-uniform durations of data transmissions from the master AP and neighboring APs, the maximum duration of the data transmission may be used to set the length field of the data transmission frame. In some embodiments, the maximum duration may be set, for example, in the L-SIG field or the duration field of the MAC header. Thus, all participating APs may add additional transmission time "padding" to align their data transmission frames with the maximum duration of the data transmission frame that will be allocated to them.

[0038] 3A illustrates a block diagram of an exemplary multi-cell communication network in which stations transmit or relay control messages to wireless communication nodes, according to some embodiments of the present invention. As shown in FIG. 3A, a master AP (MAP) 301 transmits a wireless control message to several associated stations (STAs) 303 via RF link 302. In response to receiving the wireless control message from MAP 301, STA 303 may relay the original control message or transmit an updated wireless control message to a neighbor AP (NAP) 304 via RF link 305, informing the NAP 304 that it may perform nulling transmission. In some embodiments, STA 303 may directly forward or relay the first wireless frame containing the control message received from MAP 301 that is unchanged to NAP 304. In an alternative embodiment, MAP 301 transmits the first wireless frame containing the first control message to STA 303. The first control message instructs the STA 303 to transmit a second radio frame containing a second control message to the NAP 304. The second control message instructs the NAP 304 that nulling transmission is enabled for the NAP 304. In response to receiving either the first or second control message, the NAP 304 can perform data transmission using nulling operation, for example, according to any of the methods discussed above with respect to Figures 2A-2C.

[0039] 3B illustrates a timing diagram of a method for transmitting a radio control message 306 from a master AP (MAP) to an associated station (STA), which in turn transmits an updated radio control message 307 informing a neighbor AP (NAP) that nulling transmission is enabled. As shown in FIG. 3B, the MAP transmits the radio control message 306 in a first radio frame to the STA. In some embodiments, the STA may transmit the updated radio control message 307 in a second radio frame following a short inter-message space (SIFS) interval (e.g., 16 μs) after receiving the radio control message 306. In further embodiments, the updated radio control message 307 may be an acknowledgement (ACK) message. In some embodiments, the STA may transmit the updated radio control message 307 after performing a channel contention protocol, as discussed above. Additionally, both the MAP and NAP may initiate data transmission 308 and nulling transmission 309, respectively, following a predetermined time after completion of transmission of the updated radio control message 307 from the associated station. In an alternative embodiment, the associated STA may simply relay the first radio frame containing the first control message to the NAP, as discussed above. In response to receiving either the first or second control message, the NAP 304 may perform a data transmission using nulling operation, for example, according to any of the methods discussed above with respect to Figures 2A-2C.

[0040] 4 illustrates a timing diagram of a method for transmitting a data transmission message 401 from a master AP, accompanied by a control message embedded in the data transmission message 401 indicating that a nulling transmission is enabled, according to various embodiments of the present invention. In some embodiments, the data transmission message 401 may include the identification of one or more neighboring APs that are authorized to transmit the data transmission using a nulling operation 402. For example, the data transmission message 401 may include a single AP ID, a group ID, a MAC address, or a pair ID of neighboring APs that are authorized to transmit the nulling transmission 402 to an individual station with that individual data transmission. In other embodiments, information indicating the nulling transmission, the identification of the neighboring AP, and any other additional control message / signaling may be included in the preamble or PHY header of the data transmission message 401. In some embodiments, the neighboring AP may begin transmitting data using a nulling operation 402 a predetermined period 403 after receiving the data transmission message 401, as shown in FIG. 4. In further embodiments, after receiving the control message, the neighboring AP may perform an action according to any of the methods discussed above with respect to FIGS. 2A-2C.

[0041] 5A illustrates a block diagram of an exemplary multi-cell communication network in which an interference nulling technique is implemented with a first station receiving a control message from a first communication node and transmitting response message data before receiving a data transmission, in accordance with some embodiments of the present invention. As shown in FIG. 5A, a master AP (MAP) 501 transmits a wireless control message to a first station (STA) 505 via RF link 504. In response to receiving the wireless control message from the MAP 501, the STA 505 may transmit a response message to the MAP 501 and a neighbor AP (NAP) 509 via RF links 503 and 508, respectively. The response message indicates to the NAP 509 that it is authorized to perform nulling transmissions. In some embodiments, the NAP 509 may estimate channel state information (CSI) from the response message received from the STA 505. Additionally, the NAP 509 may store channel state information (CSI) measurements. Additionally, the NAP 509 may utilize the stored CSI when forming interference-nulling beams towards the STAs 505.

[0042] In response to receiving the response message from the STA 505, the MAP 501 and the NAP 509 may initiate data transmission over the RF links 502 and 506, respectively. According to various embodiments, the NAP 509 selects a second target station (STA) 507 associated with the NAP 509 to transmit data to the target station 507 based on one or more predetermined criteria. In some embodiments, the one or more predetermined criteria is that the residual signal strength toward the first STA 505 when the NAP 509 transmits data to the second STA 507 with a nulling transmission toward the first STA 505 is less than or equal to a predetermined threshold value. Alternatively, if a target station within the wireless cell coverage of the NAP 509 does not satisfy the residual signal strength condition, the data transmission with nulling operation from the NAP 509 is discontinued.

[0043] FIG. 5B illustrates a timing diagram for transmitting a wireless control message 510 from a master AP (MAP) to a target station, which in turn transmits a response message 511 informing both the MAP and neighbor AP (NAP) that nulling transmission is enabled, according to some embodiments. In some embodiments, the wireless control message 510 may be embedded in a wireless frame. In some embodiments, the response message 511 may be contained in a wireless frame referred to as a “response frame 511.” In some embodiments, the response frame 511 may be a NULL frame. In other embodiments, the response frame 511 may be embedded in a PHY header of a wireless frame transmitted from the target station. Furthermore, the response message contained in the response frame 511 may be included in a SIG field of the wireless frame or a training signal. As shown in FIG. 5B, the MAP and NAP may initiate data transmission 512 and data transmission with nulling operation 513, respectively, a predetermined time interval after receiving the response message 511. In further embodiments, after receiving the response message 511, the NAP may perform an action according to any of the methods discussed above with respect to Figures 2A-2C.

[0044] In some embodiments, there may be several neighboring APs that cause inter-cell interference. Figure 6 illustrates a timing diagram of a method for limiting nulling transmission in the presence of several interfering neighboring APs according to various embodiments of the present invention. For example, a MAP may transmit a radio control message 601 comprising information indicating that nulling transmission is possible or desired according to a given protocol and the ID of one or more NAPs, along with other additional control messages / signaling in the preamble or PHY header of a radio frame. Furthermore, the MAP may transmit a data transmission message 602 after a predetermined amount of time. In addition, a carrier sense multiple access / collision avoidance (CSMA / CA) mechanism may be implemented in a NAP that detects or receives a nulling transmission 604 from another neighboring AP. For example, one of the NAPs may end its channel contention backoff window 603 earlier than the other NAPs and begin data transmission using nulling operation 604. In response to detecting a data transmission using nulling operation 604 from the first NAP, the other NAP may suspend its current decrement backoff counter for channel contention, thereby delaying its individual channel contention backoff procedures 605 and 606 for a predetermined time, after which the individual channel contention backoff procedures 605 and 606 are initiated again.

[0045] FIG. 7 illustrates a block diagram of a network node (NN) 700 in accordance with various embodiments of the present invention. The NN 700 is an example of a wireless communication node that can be configured to implement various methods described herein. In some embodiments, the NN 700 may be a wireless communication node such as an access point (AP) as described herein. In other embodiments, the NN 700 may be a wireless communication device such as a station (STA) as described herein. As shown in FIG. 7, the NN 700 includes a housing 740 containing a system clock 702, a processor 704, a memory 706, a transceiver 710 comprising a transmitter 712 and a receiver 714, a power module 708, and a nulling module 720.

[0046] In this embodiment, system clock 702 provides timing signals to processor 404 to control the timing of all operations of NN 700. Processor 704 controls the general operation of NN 700 and may include one or more processing circuits or modules, such as a central processing unit (CPU) and / or any combination of general-purpose microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), controllers, state machines, gate logic, discrete hardware components, dedicated hardware finite state machines, or any other suitable circuit, device and / or structure capable of performing calculations or other manipulations of data.

[0047] Memory 706, which may include both read-only memory (ROM) and random access memory (RAM), can provide instructions and data to processor 704. A portion of memory 706 can also include non-volatile random access memory (NVRAM). Processor 704 typically performs logical and arithmetic operations based on program instructions stored in memory 706. The instructions (known as software) stored in memory 406 can be executed by processor 704 to implement the methods described herein. Processor 404 and memory 706 together form a processing system that stores and executes software. As used herein, "software" refers to any type of instructions, whether referred to as software, firmware, middleware, microcode, etc., that can configure a machine or device to perform one or more desired functions or processes. Instructions can include code (e.g., in source code format, binary code format, executable code format, or any other suitable format of code). When executed by one or more processors, the instructions cause the processing system to perform various functions described herein.

[0048] The transceiver 710, including a transmitter 712 and a receiver 714, enables the NN 700 to transmit and receive data from external network nodes (e.g., STAs or APs). An antenna 750 is typically mounted in the housing 740 and electrically coupled to the transceiver 710. In various embodiments, the NN 700 includes multiple transmitters, multiple receivers, and multiple transceivers (not shown). In some embodiments, the antenna 750 includes a multi-antenna array that can form multiple beams, each pointing in a distinct direction, via MIMO beamforming techniques.

[0049] The nulling module 720 may be implemented as part of the processor 704 programmed to perform the functions herein, or may be a separate module implemented in hardware, firmware, software, or a combination thereof. According to various embodiments, the nulling module 720 is configured to perform channel state information (CSI) measurements, precoding calculations, data transmissions, or interference nulling (attenuation) functions as described herein, such as performing an acknowledgement (ACK), a clear to send (CTS), or generating a nulling transmission, as discussed above. In some embodiments, the nulling module 720 is implemented as software (i.e., computer-executable instructions) stored in a non-transitory computer-readable medium, which, when executed by the processor 704, can transform the processor 704 into a special-purpose computer to perform the nulling operations described herein.

[0050] The various components and modules discussed above within housing 740 are coupled together by a bus system 730. Bus system 730 may include a data bus, e.g., a power bus, a control signal bus, and / or a status signal bus in addition to a data bus. It should be understood that the modules of NN 700 may be operatively coupled to each other using any suitable techniques and media. It should further be understood that additional modules (not shown) may be included in NN 700 without departing from the scope of the present invention.

[0051] While various embodiments of the present disclosure have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. Similarly, various diagrams may depict example architectures or configurations provided to enable those skilled in the art to understand example features and functionality of the present disclosure. However, such skilled artisans will understand that the present disclosure is not limited to the example architectures or configurations shown, but may be implemented using a variety of alternative architectures and configurations. Additionally, as will be understood by those skilled in the art, one or more features of one embodiment can be combined with one or more features of another embodiment described herein. Thus, the scope and scope of the present disclosure should not be limited by any of the example embodiments described above.

[0052] It should also be understood that any reference to elements herein using a designation such as "first," "second," etc., does not generally limit the quantity or order of those elements. Rather, these designations may be used herein as a convenient means of distinguishing between two or more elements or instances of an element. Thus, reference to a first and a second element does not imply that only two elements may be employed or that the first element must precede the second element in some manner.

[0053] Additionally, those skilled in the art will understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, the data, instructions, commands, information, signals, bits, and symbols that may be referenced in the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

[0054] Those skilled in the art will further understand that any of the various illustrative logic blocks, modules, processors, means, circuits, methods, and functions described in connection with the aspects disclosed herein may be implemented by electronic hardware (e.g., digital implementations, analog implementations, or a combination of the two), firmware, various forms of program or design code incorporating instructions (which for convenience may be referred to herein as "software" or "software modules"), or any combination of these techniques.

[0055] To clearly illustrate this interchangeability of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software, or a combination of these techniques, depends on the particular application and design constraints imposed on the overall system. Those skilled in the art may implement the described functionality in various ways for each particular application, and such implementation decisions do not cause a departure from the scope of the present disclosure. According to various embodiments, a processor, device, component, circuit, structure, machine, module, etc. can be configured to perform one or more of the functions described herein. The terms “configured to” or “configured for,” as used herein with respect to a specified operation or function, refer to a processor, device, component, circuit, structure, machine, module, signal, etc. that is physically constructed, programmed, arranged, and / or formatted to perform a specified operation or function.

[0056] Furthermore, those skilled in the art will understand that the various illustrative logic blocks, modules, devices, components, and circuits described herein may be implemented in or by integrated circuits (ICs), which may include digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, or any combination thereof. The logic blocks, modules, and circuits may further include antennas and / or transceivers for communicating with various components within a network or device. A processor programmed to perform the functions herein may be a specially programmed or special-purpose processor, and may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in conjunction with a DSP core, or any other suitable configuration, to perform the functions described herein.

[0057] If implemented in software, the functions can be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein can be implemented as software stored on a computer-readable medium. Computer-readable media includes both computer storage media and communication media, including any medium that can enable transfer of a computer program or code from one place to another. A storage medium can be any available medium that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM, or other optical disk storage, magnetic disk storage, or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.

[0058] As used herein, the term "module" refers to software, firmware, hardware, and any combination of these elements for performing the associated functions described herein. Additionally, for purposes of discussion, various modules are described as discrete modules; however, as will be apparent to one skilled in the art, two or more modules may be combined to form a single module that performs the associated functions according to embodiments of the present disclosure.

[0059] Various modifications to the implementations described in this disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other implementations without departing from the scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the implementations shown herein, but is to be accorded the widest scope consistent with the novel features and principles disclosed herein, as recited in the following claims.

Claims

1. 1. A method for initiating a nulling transmission, the method being performed by a first wireless communication node, the method comprising: transmitting a control message to be received by a second wireless communication node, the control message instructing the second wireless communication node to initiate a channel contention procedure, and the control message informing the second wireless communication node to initiate the nulling transmission towards the first station after the channel contention procedure has been successfully completed; transmitting data to the first station during transmission of the nulling transmission from the second wireless communication node to the first station; A method comprising:

2. transmitting the data to the first station is initiated after a predetermined period of time has elapsed; The method of claim 1 , wherein the control message causes the second wireless communication node to initiate the nulling transmission after the predetermined period of time has elapsed.

3. The method further includes receiving a response message from the second wireless communication node after transmitting the control message; The predetermined period is determined based on a time when the response message is received; The method of claim 2 , wherein the nulling transmission begins after the predetermined period of time has elapsed.

4. a first duration of transmission from the first wireless communication node is included in the control message; a second duration of transmission from the second wireless communication node is included in the response message; The method of claim 3 , wherein the duration of the nulling transmission is selected to be the longer of the first duration and the second duration.

5. The method further includes transmitting the control message to the first station, thereby causing the first station to transmit a response message to be received by the second wireless communication node; the response message causes the second wireless communication node to select the second station based on whether a strength of a residual signal received by the first station as a result of a data transmission from the second wireless communication node to the second station is less than or equal to a predetermined threshold; The method of claim 1 , wherein a nulling operation is performed on the data transmission from the second wireless communication node to the second station.

6. 2. The method of claim 1, wherein the control message is received by a third wireless communication node, the control message causes the second wireless communication node and the third wireless communication node to start a channel contention procedure, and once a nulling transmission from either the second wireless communication node or the third wireless communication node is detected, the other wireless communication node suspends its channel contention procedure until the nulling transmission is no longer detected.

7. The method of claim 1 , wherein the control message includes at least one of a single ID, a group ID, a medium access control (MAC) address, and a pair ID of one or more neighboring wireless communication nodes.

8. 1. A method for providing nulling transmission, the method being performed by a first wireless communication node, the method comprising: receiving a control message from a second wireless communication node, the control message instructing the second wireless communication node to initiate a channel contention procedure, the control message informing the first wireless communication node to initiate the nulling transmission towards the first station after the channel contention procedure has been successfully completed; transmitting data to a second station during transmission of said nulling transmission to said first station; A method comprising:

9. transmitting the data to the second station is initiated after a predetermined period of time has elapsed; 9. The method of claim 8, wherein the control message causes the first wireless communication node to start the nulling transmission after the predetermined period of time has elapsed.

10. The method further includes transmitting a response message from the first wireless communication node after receiving the control message; the predetermined period is determined based on a time for transmitting the response message; The method of claim 9 , wherein the nulling transmission begins after the predetermined period of time has elapsed.

11. a first duration of transmission from the first wireless communication node is included in the response message; a second duration of transmission from the second wireless communication node is included in the control message; The method of claim 10 , wherein the duration of the nulling transmission is selected to be the longer of the first duration and the second duration.

12. The method further includes receiving a response message transmitted from the first station, the response message being transmitted in response to receiving the control message from the second wireless communication node; the received response message causes the first wireless communication node to select the second station based on whether a strength of a residual signal received by the first station as a result of a data transmission from the first wireless communication node to the second station is less than or equal to a predetermined threshold; 9. The method of claim 8, wherein a nulling operation is performed on the data transmission from the first wireless communication node to the second station.

13. 9. The method of claim 8, wherein the control message is received by a third wireless communication node, the control message causes the first wireless communication node and the third wireless communication node to start a channel contention procedure, and once a nulling transmission from either the first wireless communication node or the third wireless communication node is detected, the other wireless communication node suspends its channel contention procedure until the nulling transmission is no longer detected.

14. 1. An apparatus for wireless communication, comprising: The apparatus comprises a processor and a memory storing instructions; The instructions, when executed by the processor, transmitting a control message to be received by a wireless communication node, the control message instructing the second wireless communication node to initiate a channel contention procedure, the control message informing the wireless communication node to initiate a nulling transmission towards the first station after the channel contention procedure has been successfully completed; transmitting data to the first station during transmission of the nulling transmission from the wireless communication node to the first station; and causing the device to perform operations including:

15. transmitting the data to the first station is initiated after a predetermined period of time has elapsed; 15. The apparatus of claim 14, wherein the control message causes the wireless communication node to initiate the nulling transmission after the predetermined period of time has elapsed.

16. the operations further include receiving a response message from the wireless communication node after transmitting the control message; The predetermined period is determined based on a time when the response message is received; The apparatus of claim 15 , wherein the nulling transmission begins after the predetermined period of time has elapsed.

17. a first duration of transmission from the device is included in the control message; a second duration of transmission from the wireless communication node is included in the response message; 17. The apparatus of claim 16, wherein a duration of the nulling transmission is selected to be the longer of the first duration and the second duration.

18. 1. An apparatus for wireless communication, comprising: The apparatus comprises a processor and a memory storing instructions; The instructions, when executed by the processor, receiving a control message from a wireless communication node, the control message instructing the second wireless communication node to initiate a channel contention procedure, the control message informing the device to initiate a nulling transmission towards a first station after the channel contention procedure has been successfully completed; transmitting data to a second station during transmission of said nulling transmission to said first station; and causing the device to perform operations including:

19. transmitting the data to the second station is initiated after a predetermined period of time has elapsed; 20. The device of claim 18, wherein the control message causes the device to initiate the nulling transmission after the predetermined period of time has elapsed.

20. the operations further include transmitting a response message from the device after receiving the control message; the predetermined period is determined based on a time for transmitting the response message; 20. The apparatus of claim 19, wherein the nulling transmission begins after the predetermined period of time has elapsed.

21. a first duration of transmission from the device is included in the response message; a second duration of transmission from the wireless communication node is included in the control message; 21. The apparatus of claim 20, wherein a duration of the nulling transmission is selected to be the longer of the first duration and the second duration.

22. 2. The method of claim 1, wherein either or both of the first wireless communication node and the second wireless communication node are capable of adding additional padding to align their data transmissions.

23. 2. The method of claim 1, wherein the maximum duration of data transmission to the first station is assigned by a master access point (AP) in an L-SIG field or a duration field of a MAC header.

24. The method of claim 3 , wherein the response message is an acknowledgement (ACK) frame, a clear to send (CTS) control frame, or a NULL frame.

25. The method of claim 1 , wherein the control message includes an identification of one or more neighboring access points (APs).

26. The method of claim 1 , wherein the first wireless communication node and the second wireless communication node are configured to perform the nulling transmission using the same channel frequency and the same time.

27. The method of claim 1 , wherein the control message is transmitted in a radio frame.

28. 28. The method of claim 27, wherein the radio frame carrying the control message is an announcement or trigger frame.

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