Interference management with MIMO in a peer-to-peer network

Aspects relate to interference management in a multiple-input-multiple-output peer-to-peer network utilizing connection scheduling. When channel side information is available at both transmitter and receiver, both devices determine transmit/receiver beamforming vectors. Transmitter sends a first transmission request signal with first transmit beamforming vector and a second transmission request signal with second transmit beamforming vector in a transmission request block. Receiver estimates SINRs of the MIMO channels associated with the receive beamforming vectors and determines whether to return request response signals. Based on received request response signals, transmitter decides to transmit streams of data using the corresponding transmit beamforming vectors in the data burst. When channel side information is available only at receiver, transmitter sends one transmission request signal. Receiver estimates the SINRs of the MIMO channels associated with receive beamforming vectors using MMSE and/or successive interference cancellation (SIC), and returns request response signals in the request response block.

BACKGROUND

The following description relates generally to interference management in communication systems and more particularly to mitigating the amount of interference in a multiple-input-multiple-output peer-to-peer communication environment.

Wireless communication systems are deployed to provide various types of communication, such as voice, data, video, and others. A typical wireless communication system, or network, can provide multiple users access to one or more shared resources. For example, a system can use a variety of multiple access techniques such as Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Code Division Multiplexing (CDM), Orthogonal Frequency Division Multiplexing (OFDM), and others.

Generally, wireless communication networks are established through a mobile device communicating with a base station or access point. The access point covers a geographic range or cell and, as the mobile device is operated, the mobile device can be moved in and out of these geographic cells. A network can also be constructed utilizing solely peer-to-peer devices without utilizing access points or the network can include both access points (infrastructure mode) and peer-to-peer devices. These types of networks are sometimes referred to as ad hoc networks. Ad hoc networks can be self-configuring whereby when a mobile device (or access point) receives communication from another mobile device, the other mobile device is added to the network. As mobile devices leave the area, they are dynamically removed from the network. Thus, the topography of the network can be constantly changing.

Performance for a wireless communication system can be enhanced by using beamformed transmissions to communicate between devices. Multiple transmit antennas can be used to form beamformed transmissions. Beamformed transmissions, also referred to as beams, typically cover a narrower area than transmissions using a single transmit antenna. A beam can be considered a virtual sector allowing a virtual six-sector system to be generated from a conventional three-sector system, for example. However, the signal to interference and noise ratio (SINR) is enhanced within the area covered by the beams. The communication system can utilize a fixed or predetermined set of beams. Although the fixed beam pattern can be updated or adapted, in contrast to a beam steering system, the beams in a fixed beam system are not dynamically updated based on individual user devices.

In peer-to-peer networks, there is no central scheduler to schedule the communications links to control an amount of interference. Thus, there is a need to manage interference in multiple-input-multiple-output peer-to-peer communication environments.

SUMMARY

In accordance with one or more aspects and corresponding disclosure thereof, various aspects are described in connection with mitigating interference in a multiple-input-multiple-output (MIMO) network utilizing connection scheduling management. Transmitting devices and receiving devices can individually make a determination whether to yield no transmissions, all transmissions, or any amount of transmissions there between, as a function of priority and interference level of each transmission.

An aspect relates to a method of operating a first communication device for receiving data traffic from a second communication device in a peer-to-peer communication network. The first communication device is equipped with at least two antennas. The method includes receiving a first signal and a second signal at the at least two antennas in a transmission request time interval. Method also includes applying a first beamforming vector to the first signal received at the at least two antennas to recover a first transmission request signal from the second communication device and applying a second beamforming vector to the second signal received at the at least two antennas to recover a second transmission request signal from the second communication device. Further, method includes determining whether to send at least one request response signal to the second communication device in a subsequent request response time interval and transmitting the at least one request response signal to the second device if it is determined to send the request response signals.

Another aspect relates to a wireless communications apparatus that includes a memory and a processor. Memory retains instructions related to receiving a first signal and a second signal at two or more antennas connected to wireless communications apparatus. Memory also retains instructions related to applying a first beamforming vector to the first signal received to recover a first transmission request signal and applying a second beamforming vector to the second signal to recover a second transmission request signal. Further, memory retains instructions related to evaluating whether to send a request response signal in a subsequent request response time interval and transmitting the request response signal if the evaluation indicates to send the request response signal. Processor is coupled to the memory and is configured to execute the instructions retained in the memory.

A further aspect relates to a wireless communications apparatus that receives data traffic in a peer-to-peer communications network. Wireless communications apparatus is equipped with at least two antennas. Included in wireless communications apparatus is means for receiving a first signal and a second signal at the at least two antennas in a transmission request time interval. Also included in wireless communications apparatus is means for applying a first beamforming vector to the first signal received at the at least two antennas to recover a first transmission request signal from the second communication device. Also included is means for applying a second beamforming vector to the second signal received at the at least two antennas to recover a second transmission request signal from the second communication device. Further, wireless communications apparatus includes means for determining whether to send at least one request response signal to the second communication device in a subsequent request response time interval and means for transmitting the at least one request response signal to a second communication device if it is determined to send the request response signals.

A further aspect relates to a computer program product comprising a computer-readable medium. Computer-readable medium includes a first set of codes for causing a computer to receive a first signal and a second signal at two antennas in a transmission request time interval. Also included is a second set of codes for causing the computer to apply a first beamforming vector to the first signal received at the two antennas to recover a first transmission request signal. Also included is a third set of codes for causing the computer to apply a second beamforming vector to the second signal received at the at least two antennas to recover a second transmission request signal. Further, computer-readable medium includes a fourth set of codes for causing the computer to determine whether to send at least one request response signal and a fifth set of codes for causing the computer to transmit the at least one request response signal.

Another aspect relates to at least one processor configured to receive data traffic in a peer-to-peer communication network. Processor includes a first module for receiving a first signal and a second signal at two or more antennas and a second module for applying a first beamforming vector to the first signal received to recover a first transmission request signal. Also included is a third module for applying a second beamforming vector to the second signal to recover a second transmission request signal. Further, processor includes a fourth module for evaluating whether to send a request response signal in a subsequent request response time interval and a fifth module for transmitting the request response signal if the evaluation indicates to send the request response signal.

Yet another aspect relates to a method of operating a first communication device for transmitting data traffic to a second communication device in a multiple-input-multiple-output peer-to-peer communication environment. The first device is equipped with at least two antennas. Method comprises transmitting a first transmission request signal with a first beamforming vector and a second transmission request signal with a second beamforming vector. The first and second transmission request signals are transmitted by the at least two antennas. Method also includes receiving signals at the at least two antennas in a subsequent request response time interval and recovering from the received signals at least one request response signal from the second communication device. The at least one request response signal corresponds to the first transmission request signal and the second transmission request signal. Further, method includes determining whether to send a data traffic signal to the second communication device as a function of the recovered request response signal and transmitting the data traffic signal to the second communication device if it is determined to send the data traffic signal.

Another aspect relates to a wireless communications apparatus that includes a memory and a processor. Memory retains instructions related to sending a first transmission request signal with a first beamforming vector and a second transmission request signal with a second beamforming vector. The first and second transmission request signals are sent by at least two antennas. Memory also retains instructions related to receiving signals at the at least two antennas in a subsequent request response time interval and recovering from the received signals at least one request response signal. The at least one request response signal corresponds to the first transmission request signal and the second transmission request signal. Additionally, memory retains instructions related to determining whether to send a data traffic signal as a function of the recovered request response signal and transmitting the data traffic signal if it is determined to send the data traffic signal. Processor is coupled to the memory and is configured to execute the instructions retained in the memory.

Yet another aspect relates to a wireless communications apparatus that transmits data traffic in a multiple-input-multiple-output peer-to-peer communication environment. Wireless communications apparatus includes means for transmitting a first transmission request signal with a first beamforming vector and a second transmission request signal with a second beamforming vector. The first and second transmission request signals are transmitted by at least two antennas. Wireless communications apparatus also includes means for receiving signals at the at least two antennas in a subsequent request response time interval and means for recovering from the received signals at least one request response signal from a communication device. The at least one request response signal corresponds to the first transmission request signal and the second transmission request signal. Wireless communications apparatus also includes means for determining whether to send a data traffic signal to the communication device as a function of the recovered request response signal and means for transmitting the data traffic signal to the communication device if it is determined to send the data traffic signal.

Still another aspect relates to a computer program product comprising a computer-readable medium. Included in computer-readable medium is a first set of codes for causing a computer to transmit a first transmission request signal with a first beamforming vector and a second transmission request signal with a second beamforming vector. The first and second transmission request signals are transmitted by at least two antennas. Computer-readable medium also includes a second set of codes for causing the computer to receive signals at the at least two antennas in a subsequent request response time interval and a third set of codes for causing the computer to recover from the received signals at least one request response signal. The at least one request response signal corresponds to the first transmission request signal and the second transmission request signal. Further, computer-readable medium includes a fourth set of codes for causing the computer to determine whether to send a data traffic signal as a function of the recovered request response signal and a fourth set of codes for causing the computer to transmit the data traffic signal if it is determined to send the data traffic signal.

A further aspect relates to at least one processor configured to transmit data traffic to a second communication device in a multiple-input-multiple-output peer-to-peer communication environment. Processor includes a first module for transmitting a first transmission request signal with a first beamforming vector and a second transmission request signal with a second beamforming vector. The first and second transmission request signals are transmitted by at least two antennas. Processor also includes a second module for receiving signals at the at least two antennas in a subsequent request response time interval and a third module for recovering from the received signals at least one request response signal. The at least one request response signal corresponds to the first transmission request signal and the second transmission request signal. Further, processor includes a fourth module for determining whether to send a data traffic signal as a function of the recovered request response signal and a fifth module for transmitting the data traffic signal.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of the various aspects can be employed. Other advantages and novel features will become apparent from the following detailed description when considered in conjunction with the drawings and the disclosed aspects are intended to include all such aspects and their equivalents.

DETAILED DESCRIPTION

Furthermore, various aspects are described herein in connection with a mobile device. A mobile device can also be called, and may contain some or all of the functionality of a system, subscriber unit, subscriber station, mobile station, mobile, wireless terminal, node, device, remote station, remote terminal, access terminal, user terminal, terminal, wireless communication device, wireless communication apparatus, user agent, user device, or user equipment (UE), and the like. A mobile device can be a cellular telephone, a cordless telephone, a Session Initiation Protocol (SIP) phone, a smart phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a laptop, a handheld communication device, a handheld computing device, a satellite radio, a wireless modem card and/or another processing device for communicating over a wireless system. Moreover, various aspects are described herein in connection with a base station. A base station may be utilized for communicating with wireless terminal(s) and can also be called, and can contain some or all of the functionality of, an access point, node, Node B, e-NodeB, e-NB, or some other network entity.

Various aspects or features will be presented in terms of systems that can include a number of devices, components, modules, and the like. It is to be understood and appreciated that the various systems can include additional devices, components, modules, etc. and/or cannot include all of the devices, components, modules etc. discussed in connection with the figures. A combination of these approaches may also be used.

Referring now toFIG. 1, illustrated is a system100for mitigating interference through utilization of connection scheduling management, according to an aspect. System100is configured to provide an interference mitigation mechanism when at least a subset of devices within system100are equipped with multiple transmit/receive antennas and spatial multiplexing Multiple-Input-Multiple-Output (MIMO) antenna technology for communications between devices. Further, system100can be a peer-to-peer network in which devices communicate directly without utilization of a centralized scheduler (e.g., access point).

System100includes at least two communication apparatuses102,104that are configured to convey information. System100is illustrated as including one transmitter device102and one receiver device104. However, it should be understood that multiple transmitter devices102and multiple receiver devices104can be utilized in system100, sometimes referred to as communication network or network. Further, although various aspects will be discussed with reference to a transmitter102and a receiver104performing separate functions, it should be understood that a transmitter102can also perform functions of receiving, as disclosed herein, and a receiver104can also perform functions of transmitting, as disclosed herein. Alternatively or additionally, receiver104can be a communication initiation device and transmitter102can be the device receiving the request for initiation of communication. That is to say, at times the roles of transmitter102and receiver104can be reversed.

In a MIMO scheme, both transmitting device102and receiving device104are equipped with multiple antennas. For the purposes of description, consider that each of transmitting device102and receiving device104is equipped with two antennas. Transmitting device102intends to transmit two sets of information bits to receiving device104in a given traffic segment. The two sets of information bits are encoded and modulated. Denote the corresponding sets of modulation symbols to be {A1, A2, . . . } and {B1, B2, . . . } respectively. In the MIMO scheme, transmitting device102uses a transmit matrix [S1, T1; S2, T2] so that the first antenna transmits symbols A1*S1+B1*T1, A2*S1+B2*T1, and so on, and the second antenna transmits symbols A1*S2+B1*T2, A2*S2+B2*T2and so on. In the traffic segment, receiving device104receives two sets of symbols in its antennas, which are denoted to be {C1, C2, . . . } in the first antenna and {D1, D2, . . . } in the second antenna. To recover the two sets of information bits transmitted from transmitting device102, in the MIMO scheme, receiving device104uses a receive matrix [U1, V1; U2, V2]. Specifically, receiving device104calculates a first set of demodulation symbols as C1*U1+D1*V1, C2*U1+D2*V1, and so on, and a second set of demodulation symbols as C1*U2+D1*V2, C2*U2+D2*V2, and so on. Receiving device104uses the first set of demodulation symbols to recover the first set of information bits, and the second set of demodulation symbols to recover the second set of information bits. It should be noted that the choice of transmit and receive matrices may depend on the MIMO channel between the transmitting and receiving devices and be designed to diagonalize the combined channel matrix (combining the transmit matrix, MIMO channel matrix, and the receive matrix).

In the receiver beam forming scheme, only receiving device104is required to be equipped with multiple antennas. Transmitting device102may be equipped with multiple antennas as well, according to some aspects. For purposes of explanation, consider that receiving device104is equipped with two antennas. Transmitting device102intends to transmit one set of information bits to receiving device104in a given traffic segment. In the traffic segment, receiving device104receives two sets of symbols in its antennas, which are denoted to be {E1, E2, . . . } in the first antenna and {F1, F2, . . . } in the second antenna. To recover the set of information bits transmitted from transmitting device102in the receiver beam forming scheme, receiving device104uses a receive vector [W1, W2]. Specifically, receiving device104calculates a set of demodulation symbols as E1*W1+F1*W2, E2*W1+F2*W2, and so on. Note that the choice of receive vector may be designed to maximize the signal to interference plus noise ratio.

In an exemplary system, before the traffic segment is transmitted, transmitting device102first sends a transmission request signal to receiving device104to indicate the transmission intention. Since the wireless channel is a shared medium, other devices in the vicinity also receive the transmission request signal. Based on the received power of the transmission request signal, those devices can predict the potential interference in the traffic channel that may be received from transmitting device102if transmitting device102proceeds to transmit the intended traffic segment.

After receiving the transmission request, receiving device104may send a request response signal to indicate that receiving device104is ready to receive the intended traffic segment from transmitting device102. According to some aspects, receiving device104may choose not to send the request response signal. For example, receiving device104may intend to receive a traffic segment from a different transmitting device. Receiving device104may detect other transmission request signals in the vicinity and predict that the potential interference caused by other traffic segment transmissions in the traffic channel would be significant. Suppose that the request response signal has been sent. Since the wireless channel is a shared medium, other devices in the vicinity also receive the request response signal. Based on the received power of the request response signal, each of those devices can predict the potential interference in the traffic channel that it may generate to receiving device if it proceeds to transmit a traffic segment and, therefore, determine whether to transmit a traffic segment.

In the above exemplary system, the protocol of transmission request and request response signals enables distributed scheduling and interference management among multiple transmitting and receiving devices in the vicinity. In an aspect, where OFDM is used as a base signaling scheme, a transmission request signal or request response signal is sent over a tone in an OFDM symbol. The specific position of the tone and the OFDM symbol may be reserved to be used exclusively by the communication pair of transmitting device102and receiving device104.

For example, in the receiver beam forming scheme, transmitting device102and receiving device104may have one specific position of the tone and the OFDM symbol to send the transmission request and another corresponding specific position of the tone and the OFDM symbol to send the request response signal. Those specific positions are reserved exclusively to the communication pair of transmitting device102and receiving device104.

In the MIMO scheme, as discussed above, transmitting device102may intend to send two data streams in a given traffic segment to receiving device104. In an aspect, transmitting device102may send two separate transmission requests to receiving device104, one transmission request for each data stream. Each of the transmission requests is sent over a tone in an OFDM symbol and the specific position of the tone and the OFDM symbol is reserved by the communications pair. Transmitting device102utilizes a first beamforming vector [S1, S2] to send the first transmission request and a second beamforming vector [T1, T2] to send the second transmission request. Thus, at the specific position of the tone and the OFDM symbol reserved for the first transmission request, a first symbol S1is sent at the first antenna and a second symbol S2is sent at the second antenna. In a similar manner, at the specific position of the tone and the OFDM symbol reserved for the second transmission request, a second symbol T1is sent at the first antenna and a second symbol T2is sent at the second antenna.

Receiving device104utilizes a first receive beamforming vector [U1, V1] to receive the first transmission request and a second receive beamforming vector [U2, V2] to receive the second transmission request. Thus, at the specific position of the tone and the OFDM symbol reserved for the first transmission request, a first symbol C1is received at the first antenna and a second symbol D1is received at the second antenna. Receiving device104combines C1and D1to obtain a combined symbol C1*U1+D1*V1for the first received transmission request. In a similar manner, at the specific position of the tone and the OFDM symbol reserved for the second transmission request, a first symbol C2is received at the first antenna and a second symbol D2is received at the second antenna. Receiving device104combines C2and D2to obtain a combined symbol C2*U2+D2*V2for the second received transmission request.

If receiving device104intends to receive both data streams, receiving device104may send two separate request responses to transmitting device102, one for each data stream. Each of the request responses is sent over a tone in an OFDM symbol and the specific position of the tone and the OFDM symbol is reserved by the communications pair. Receiving device104utilizes the first receive beamforming vector [U1, V1] to send the first request response and the second receive beamforming vector [U2, V2] to send the second request response. Thus, at the specific position of the tone and the OFDM symbol reserved for the first request response, a first symbol U1is sent at the first antenna and a second symbol V1is sent at the second antenna. In a similar manner, at the specific position of the tone and the OFDM symbol reserved for the second request response, a first symbol U2is sent at the first antenna and a second symbol V2is sent at the second antenna.

Receiving device104may determine to receive only one of the data streams, in which case receiving device104may send one request response in one of the two reserved positions utilizing the corresponding receive beamforming vector.

In the above exemplary system, the reserved channel resource for sending transmission requests and request responses are system resources in the sense that it needs to be shared among all the communication pairs that intend to communicate in the vicinity. For example, the total channel resource for sending transmission requests and request responses may be fixed. As more and more communication pairs reserve channel resource for sending their transmission requests and request responses, the remaining resource for new communication pairs becomes less and less. In particular, as described above, a communication pair may reserve one piece of channel resource if the receiver beam forming scheme is used or two pieces of channel resource if the MIMO scheme is used. Thus, the communication pair occupies more channel resource if the MIMO scheme is used than if the receiver beam forming scheme is used.

For purposes of discussion, a channel matrix106,108(or channel side information) between transmitter102and receiver104is available at both devices102,104. For example, knowledge of the channel matrix is possible in a Time Division Duplex (TDD) type of system when channel is static since channel estimation is not expensive in a TDD environment. The channel information can be obtained through various techniques and these techniques will not be discussed herein for purposes of simplicity. When channel side information is available at both transmitter102and receiver104, a Singular Value Decomposition (SVD) technique can be utilized. After SVD, both transmitter102and receiver104are aware of the transmit/receive beamforming vectors that should be utilized for the transmission and the channel between devices102,104simply becomes a vector channel with no correction in between.

The disclosed aspects relate to a situation when multiple transmitting devices are to communicate with respective multiple receiving devices. In order to provide context for the disclosed aspects,FIG. 2illustrates a schematic representation200of communication between network nodes utilizing a single antenna. Illustrated are four devices, Device A202, Device B204, Device C206, and Device D208. Devices A202and C206can be transmitters (e.g., transmitting device102ofFIG. 1) and Devices B204and D206can be receivers (e.g., receiving devices104ofFIG. 1). For purposes of this discussion, Device A202discovered and has data to communicate over a link210with Device B204and Device C206discovered and has data to communicate over a link212with Device D208. A distribution scheduling decision can be made to determine whether only one of the links210,212should transfer at a given time or whether both links210,212can transmit at substantially the same time.

Each link210,212can have a distinct Connection Identifier (CID), which can be a number between “1” and “168”, for example. A protocol can be utilized that assigns a different number to each connection or link210,212. The techniques utilized to assign the CID can be any technique for assigning the CID and will not be discussed further herein. For purposes of explanation, link210has a CID of “15” and link212has a CID of “27”. Based on the CIDs, there are connection scheduling grids300for a single antenna, examples of which are illustrated inFIG. 3.

Illustrated at302is a Transmit (Tx) block, which is utilized to make a transmission request, and at304is a Receive (Rx) block, which is utilized to reply to the request by sending a request response. As a function of the CID and the particular time, one tone at one OFDM symbol is assigned in Tx block302and one tone at one OFDM symbol in Rx block304. For example, node A202(ofFIG. 2) is assigned tone306and Node C206is assigned tone308in Tx block302. In Rx block304, Node B204is assigned tone310and Node D208is assigned tone312. If Node A202has a request to send to Node B204, Node A202places energy in tone306, which is the tone associated with CID “15” (link210) at this time. In a similar manner, if Node C206has a request for Node D208, Node C206places energy in tone308, which is the tone associated with CID “27” (link212) at this time.

Each receiving node (e.g., receiver104ofFIG. 1) utilizes the notion of priority, which indicates that the physical order in which the tones are placed determines the priority. In this example, since tone306(Node A202) is ahead of tone308(Node C206), Node A202has a higher priority than Node C206. Thus, connection A-B (link210) has a higher priority than connection C-D (link212).

Nodes B204and D208monitor the entire TX block302and each node204,208determines whether to yield or whether it does not need to yield. Node B204evaluates Tx block302and identifies the requests306and308and determines that request306(from Node A202) is a higher priority. Thus, Node B204determines that it does not have to yield. Node D208, however, evaluates the requests306and308and determines that request308(from Node C206) is a lower priority than request306(from Node A202) and a determination whether to yield to Node A202should be performed by Node D208. Node D208can make the determination based on a power measurement (e.g., Signal to Interference Plus Noise Ratio (SINR)). Thus, Node D208measures these two powers (in tones206and208) to obtain an estimate that indicates if Node A202and Node C206were to transmit at substantially the same time, whether the signal from Node C206will be received at Node D208with sufficient SINR. If there is a potential that the signal will not be received (e.g., Node A202causes too much interference) with sufficient SINR, Node D208will yield.

Nodes A202and C206monitor Rx Block304to determine whether the corresponding Nodes returned an echo (e.g., request response), which confirms receipt of the transmission request. If a node yielded, it will not return an echo. For purposes of this example, Node D312did not perform Rx yielding (e.g., the determination is that excessive interference would not be encountered). Thus, in Rx block304, the receivers (Nodes B204and D208) would send request responses, confirming receipt of respective transmission requests306,308. Thus, Node B204will return an echo310and Node D208will return an echo312.

Nodes A202and C206are monitoring Rx Block304and can perform a protocol referred to as transmit (Tx) yielding. Thus, Node A202will review Rx Block304and evaluate the echoes310and312and determine echo310has a higher priority (e.g., it is ahead of echo312). Since echo310is for Node A202, Node A202does not need to yield. However, Node C206will evaluate the echoes310and312and determine that the echo312from Node D308is a lower priority. Node C206will ascertain whether it needs to yield. Thus, Node C206determines that if it were to transmit, whether the traffic signal from Node C206would cause excessive interference to Node B204and, therefore, damage the higher priority communication from Node A202to Node B204. If the determination is that there is not too much interference (e.g., the interference cost is low), Node C206will not yield. If there is too much interference (e.g., the interference cost is high), Node C206will yield.

Denote Pa, Pb, and Pcto be the transmission powers of Node A202, Node B204, and Node C206, respectively. Denote haband hbcto be the channel gain between Node A202and Node B204and between Node B204and Node C206, respectively. Thus, the received power of the transmission request306at Node B204is equal to Pahab. Using an inverse power

Pb=CPa⁢hab,
where C is a constant. The received power of the request response310at Node C206is equal to

ChbcPa⁢hab.
Node C206can multiply that quantity with the transmission power of Node C206to calculate an interference cost to Node B204:

Chbc⁢PcPa⁢hab.
It can be shown that the interference cost is inversely proportional to the SINR at Node B204assuming Node C206is the only interferer. Therefore, Node C206may use the above interference cost to determine whether to yield.

As stated, the above discussion relates to a single-input-single-output situation. The disclosed aspects relate to Multiple-Input-Multiple-Output (MIMO), or devices that have multiple transmit antennas and multiple receive antennas. Thus, the disclosed aspects will now be discussed with reference toFIG. 1andFIG. 4, which illustrates connection scheduling grids400for a MIMO system. Illustrated at402is an example transmit block (Tx Block) and at404is an example receive block (Rx Block). For purposes of describing the various aspects, the features will be described with reference to two transmit antennas and two receive antennas (a 2-by-2 case). However, the disclosed aspects can be easily extended to more general scenarios. In a 2-by-2 case, transmitter102sends a first transmit request signal406or408(depending on which device is performing the transmitting, Node A202or Node C206) with a first transmit beamforming vector and a second transmit request signal410or412with a second transmit beamforming vector in a transmit request block, illustrated at402.

The first signal and the second signal are received at the two or more antennas110,112of receiver104(Node B204or Node D208). The signals can be received in a transmission request time interval. In accordance with some aspects, first signal and second signal are received in two distinct channel resources, wherein one channel resource corresponds to at least one tone in an OFDM symbol.

A first beamforming vector module114is configured to apply a first beamforming vector to the first received signal to recover a first transmission request signal from transmitter102. A second beamforming vector module116is configured to apply a second beamforming vector to the second signal received at the antennas110,112to recover a second transmission request signal from transmitter102.

Also included in receiver104is an interference module118that is configured to estimate an interference amount. A first interference amount associated with the first transmission request signal and a second interference amount associated with the second transmission request signal can be estimated by interference module118. In accordance with some aspects, the first interference amount is indicative of the power of an interference to be seen by receiver104when a data traffic is received from transmitter102that uses the first beamforming vector. Therefore, receiver104of Node D208uses the first beamforming vector to combine the interfering requests received at the two antennas in the Tx Block402to determine the interference power for the first transmission request. Given the priority among406,408,410, and412, illustrated inFIG. 4, the two interfering requests are406and410. Receiver410of Node D208utilizes the first beamforming vector to combine the signal received at the two antennas in408to determine the signal power of the first transmission request.

The second interference amount is indicative of a power of an interference to be seen by receiver104when a data traffic is received from transmitter102that uses the second beamforming vector. Therefore, receiver104of Node D408utilizes the second beamforming vector to combine the interfering requests received at the two antennas in the Tx Block402to determine the interference power for the second transmission request. Given the priority among406,408,410, and412, illustrated inFIG. 4, the two interfering requests are406and410. Receiver104of Node D208utilizes the second beamforming vector to combine the signal received at the two antennas in412to determine the signal power of the second transmission request. Note that inFIG. 4the transmission requests406and410both are of a higher priority than transmission requests408and412. Therefore, when receiver104of Node D208calculates the interference power for both the first and second transmission requests408and412, receiver104includes the received power of both406and410. Due to the fact that the first and second beamforming vectors are most likely different, the interference power determined for the first transmission request may be different from the interference power determined for the second transmission request.

In a different scenario (not illustrated), suppose that the priority order from high to low is transmission requests406,408,410, and412. In this case, when receiver104of Node D208calculates the interference power for the first transmission request408, receiver104includes the received power of only406because406is of higher priority than408, but410is of lower priority than408. However, when receiver104of Node D208calculates the interference power for the second transmission request412, receiver104includes the received power of both406and410because both406and410are of higher priority than412.

A response determiner120is configured to decide whether to send one or more request response signals to transmitter102in a subsequent request response time interval. The decision by response determiner120can be made, in part, as a function of the estimated first interference amount, the second interference amount, or both the estimated first interference amount and the estimated second interference amount. According to some aspects, it is determined to send at least one request response signal if first interference amount is below a certain threshold and if second interference amount is below the certain threshold. For example, the ratio of the first interference amount and the first signal amount is below a certain threshold.

A transmitter122is configured to transmit the one or more request response signals (414,416or418,420). One or more of the request response signals can comprise a first request response signal that corresponds to the first transmission request signal and can be sent if the first interference amount is below a certain threshold. According to some aspects, the one request response signal can comprise a second request response signal that corresponds to the second transmission request signal. The second request response signal can be determined to be sent if the second interference amount is below a certain threshold. The second request response signal can be transmitted with a second beamforming vector. According to some aspects, the interfering transmission request signal is of a higher priority than the second transmission request signal from transmitter102. The second interference amount can be estimated as a function of a power of the recovered interfering transmission request signal.

Response determiner120can independently determine whether to send the first request response signal corresponding to the first transmission request and whether to send the second request response signal corresponding to the second transmission request. Response determiner120may determine to transmit both request responses, only one request response, or no request responses. Even if the first transmission request may have higher priority than the second transmission request, response determiner120may decide to send the second request response and to not send the first request response, as the second interference amount may be less than the first interference amount since different beamforming vectors are being used to receive the first and second transmission request signals.

In accordance with some aspects, the first request response signal is transmitted with a first beamforming vector. For example, transmitter102can utilize two receive beamforming vectors in receiver block404. It should be noted that the signals406-420can be located anywhere in the respective blocks402,404and the locations shown are for illustration purposes only. The signals406,410sent by Node A can be referred to as transmit eigenvectors VAB+and the signals408,412sent by Node C can be referred to as transmit eigenvectors VCD+. The signals414,418sent by node B can be referred to as receive eigenvectors UAB+and the signals416,420sent by Node D can be referred to as receive eigenvectors UCD+. Since the channel matrix106,108is known by both devices, a singular value composition can be constructed for the link between Nodes A and B as:
HAB=UABVABEquation 2.

For a MIMO system, the transmission yielding protocol can be performed at both transmitter102and receiver104, which is similar to the single antenna situation described above. For the receiving yielding portion, receiver104receives each tone or vector (e.g., vectors406and410). An independent decision on the two vectors406,410that receiver104might receive in the data traffic can be conducted. For example, a priority evaluator124can be configured to recover an interfering transmission request signal in the transmission request time interval and determine a priority level. The interfering transmission request signal might be a higher priority than the first transmission request signal from transmitter102and the first interference amount can be estimated as a function of the power of the recovered interfering transmission request signal.

According to some aspects, the interfering transmission request signal is sent by a third device (e.g., Node C206ofFIG. 2) to a fourth device (e.g., Node D208ofFIG. 2). Interfering transmission request signal indicates that third device intends to send a data traffic signal to fourth device and this signal will interfere with the data traffic signal to be sent from transmitter102(e.g., Node A202ofFIG. 2) to receiver104(e.g., Node B204ofFIG. 4).

In accordance with some aspects, this determination can be performed by priority evaluator124that ascertains whether there is a higher priority transmission. For example, priority evaluator124can determine whether vector406is a higher priority than vector408and/or whether vector410is a higher priority than vector412. This determination can be made by priority evaluator124as a function of the physical order in which the vectors are assigned in the block402.

If priority evaluator124determines that the vectors for apparatus102are a higher priority, there is no yielding. However, if priority evaluator124determines that another communication link has a higher priority, the amount of interference that would be seen on the communication link is measured. The higher priority vector (e.g., vector410) can be multiplied with the beamforming vector (e.g., vector412) receiver104will utilize. Thus, the first and second eigenvectors are multiplied to calculate the interference impact after performing beamforming.

Based on the observation, response determiner120can perform Rx yielding to decide to reply with two transmit request responses, one transmit request response (yield one of the transmit requests), or none (yield both transmit requests from transmitter102). Thus, the echo sent by Node B can be UABfirst vector and UABsecond vector. In a similar manner, the echo sent by Node D can be UCDfirst vector and UCDsecond vector. If yielding is not performed, transmitter122sends the signal in the direction of the vector.

In accordance with some aspects, a data traffic signal from transmitter can be received, at antennas110,112, subsequent to transmitting the one or more request response signals. The first beamforming vector can be applied to the received data traffic signal to recover a first set of data information.

In accordance with some aspects, a data traffic signal is received from transmitter102subsequent to transmitting the one or more request response signals. The first beamforming vector can be applied to the received data traffic signal to recover a first set of data information. The second beamforming vector can be applied to the received data traffic signal to recover a second set of data information.

According to some aspects, receiver104includes a beamforming vector evaluator126that is configured to calculate a first beamforming vector and a second beamforming vector for receiving data traffic from transmitter102before receiving the signals at the two antennas in the transmission request time interval.

At the transmitter102side (Node A202or Node C206), based on signals received at transmission request response block, transmitter102can make a determination whether to transmit zero, all, or a subset of the streams of data utilizing pre-determined beamforming vectors in the data burst. Additional description is provided with reference toFIG. 5.

In some situations, the transmitter does not have the MIMO channel information, that is to say, the transmitter cannot determine the singular value decomposition (SVD) method to diagonalize the channel matrix. However, the receiver side information is available. In this case, two transmit antennas will transmit two different streams of data with a similar power (P/2) during a data burst without applying any beamforming vector. For example, each of the two transmit antennas transmit one of the two data streams. The receiver antennas will receive two non-orthogonal data streams and can apply minimum mean-squared error (MMSE) to separate and recover the two data streams. In accordance with some aspects, MMSE can be utilized with Successive-Interference-Cancellation (SIC) to orthogonalize the two data streams. In this case, due to the correlation between the two streams, a level of heuristics can be introduced.

On the transmitter102side, only one transmission request signal should be transmitted using power P (instead of power P/2). Power P is utilized because the effect of two antennas transmitting independent data streams with power P/2 is about the same as a single antenna transmitting power P to neighboring users (e.g., receiver104). The receiver104will send back two transmit request response signals in the transmit request response block. Receiver104can transmit these response signals using the two beamforming vectors that would be utilized in the data transmission block, if receiver104decides not to yield for the current data transmission. Those two beamforming vectors are determined, for example, according to the MMSE principle to maximize the SINR when the two data streams are to be recovered.

In accordance with some aspects, due to the correlation between two streams, receiver104might decide to yield the current data transmission block whenever this is a higher-priority strong interferer for either of its two streams. The transmitter yielding mechanism occurs similar to the single antenna case.

System100can include memory130operatively coupled to receiver104. Memory130can be external to receiver104or can reside within receiver104. Memory130can store information related to receiving signals that are intended for receiver104. Memory130can also store information related to applying beamforming vectors to the signals to recover respective transmission request signals and ascertaining if request response signals should be transmitted. Memory130can further store instructions related to determining an interference amount of the second transmission if the priority level of the at least a second transmission is higher than the priority level of the second steam of data. Further instructions can relate to yielding zero or more transmit request responses as a function of an independent review of the priority levels and the interference amounts. Further, memory130can store other suitable information related to signals transmitted and received in a communication network. A processor132can be operatively connected to receiver104(and/or memory130) to facilitate analysis of information related to interference management in a communication network. Processor132can be a processor dedicated to analyzing and/or generating information received by receiver104, a processor that controls one or more components of system100, and/or a processor that both analyzes and generates information received by receiver104and controls one or more components of system100.

FIG. 5illustrates a system500for transmitting data traffic to mitigate interference in a communication network, according to an aspect. System500includes at least two communication apparatuses502,504that are configured to convey information. It should be understood that multiple transmitter devices502and multiple receiver devices504can be utilized in system500(also referred to as communication network, network, or similar terms). Further, although various aspects will be discussed with reference to a transmitter502and a receiver504performing separate functions, it should be understood that both transmitter502and receiver504can perform dual functions of both transmitting and receiving.

Transmitter502sends a first transmission request signal with first transmit beamforming vector and a second transmission request signal with second transmit beamforming vector in a transmission request block. Receiver504estimates SINRs of the MIMO channels associated with the receive beamforming vectors and determines whether to return request response signals. Based on received request response signals, transmitter502decides to transmit streams of data using the corresponding transmit beamforming vectors in the data burst. When channel side information is available only at receiver504, transmitter502sends one transmission request signal. Receiver504estimates the SINRs of the MIMO channels associated with receive beamforming vectors using MMSE and/or successive interference cancellation (SIC), and returns request response signals in the request response block.

In further detail, transmitter502includes a transmitter module506that is configured to send a first transmission request signal with a first beamforming vector and a second transmission request signal with a second beamforming vector. The first and second transmission request signals can be transmitted by two antennas508,510. In accordance with some aspects, first and second transmission request signals are transmitted in two distinct channel resources, wherein one channel resource corresponds to at least one tone in an OFDM symbol, for example,406and410to be transmitted by Node A202, or408and412for Node C206. A receiver module512receives signals, at the two antennas508,510in a subsequent request response interval, for example,414and418to be received by Node A202, or416and420for Node C206.

An extraction module514is configured to recover from the received signals at least one request response signal from receiver504. The response signal can correspond to the first transmission request signal and the second transmission request signal. As a function of the recovered request response signal, an evaluation module516can determine whether to send a data traffic signal to receiver504. If sent, the data traffic signal is conveyed by transmitter module506.

According to some aspects, the received signals include a first signal and a second signal that are received in two distinct channel resources that respectively correspond to distinct channel resources in which the first and second transmission request signals are transmitted. The one (or more) request response signal can include a first and a second request response signal that correspond to the first and second transmission request signals respectively. The first request response signal can be recovered by extraction module514by applying the first beamforming vector to the first received signal (e.g.,414received at Node A202, or416received at Node C206) and the second request response signal (e.g.,418received at Node A202, or420received at Node C) can be recovered by applying the second beamforming vector to the second received signal.

Transmitter502can also include a cost estimator518that is configured to estimate interference cost amounts associated with each transmission request signal. The determination by evaluation module516of whether to send data traffic signals can be a function of one or more of the estimated interference cost amounts. For example, it might be determined to transmit a first data traffic signal if the recovered first request response signal is positive and the estimated first interference cost amount is below a certain threshold. The recovered first request response signal is positive if the power of the recovered first request response signal exceeds a threshold.

In accordance with some aspects, transmitter502includes a coded modulation symbol creator520that is configured to generate coded modulation symbols. For example, coded modulation symbol creator520can generate a first set of coded modulation symbols from a first set of data information. A first beamforming vector is applied to the first set of coded modulation symbols, by a vector module522, to generate the first data traffic signal, which is transmitted by transmitter module506in the channel resources of a traffic channel segment at the two antennas508,510.

Further, coded modulation symbol creator520can generate a second set of coded modulation symbols from a second set of data information. Vector module522applies the second beamforming vector to the second set of coded modulation symbols to generate the second data traffic signal, which is sent by transmission module506in the channel resources of the same traffic channel segment as the first data traffic signal.

In accordance with some aspects, receiver module512receives an interfering request response signal, at the two antennas508,510in the request response time interval. The interfering transmission request signal can be a higher priority than the first request response signal from receiver504. For example, inFIG. 4, Node C receives the first and second request response signals416and420from Node D and, in addition, the interfering request response signals414and418from Node B, wherein414and418are both of higher priority than416and420(in this example). In this case, when the first beamforming vector is utilized to recover the first request response signal416from Node D, vector module520of Node C can apply the same first beamforming vector to the received interfering request response signal (414and418) received at the two antennas to obtain a first resultant signal. Given the priority among414,416,418, and420illustrated inFIG. 4, the two interfering request responses are414and418. The first interference cost amount can be estimated by cost estimator518as a function of the power of the first resultant signal. According to some aspects, the interfering request response signal is sent by a third device (Node B) to a fourth device (Node A). The interfering request response signal can indicate that third device intends to receive a data traffic signal from fourth device and will be interfered by the data traffic signal to be sent from transmitter502(Node C) to receiver504(Node D). Alternatively or additionally, the first interference cost amount is indicative of the power of an interference or SINR to be seen by third device when transmitter502transmits a data traffic to receiver504using the first beamforming vector. In accordance with some aspects, the first interference cost amount can be estimated as a function of the transmission power of the first transmission request signal.

In accordance with some aspects, it might be determined to transmit a second data traffic signal if the recovered second request response signal is positive (e.g., the second request response signal is successfully detected or recovered) and the estimated second interference cost amount is below a certain threshold. Receiver module512receives an interfering request response signal at the two antennas508,510. The interfering request response signal can be received in the request response time interval and can be a higher priority than the second request response signal from receiver504. While the second beamforming vector is utilized to recover the second request response signal420from Node D, vector module522can apply the second beamforming vector to the received interfering request response signal (414and418) received at the two antennas to obtain a second resultant signal. Given the priority among414,416,418, and420(illustrated inFIG. 4), the two interfering request responses are414and418. The second interference cost amount can be estimated by cost estimator518as a function of the power of the second resultant signal. Further, the second interference cost amount can be estimated as a function of the transmission power of the second transmission request signal. Note that inFIG. 4, request responses414and418both are of higher priority than request responses416and420. Therefore, when Node C calculates the interference cost of both the first and second request responses416and420, Node C should take into account the received power of both414and418. Since the first and second beamforming vectors are probably different, the interference cost determined for the first request response may be different from that determined for the second request response.

In a different scenario (not illustrated), suppose that the priority order from high to low is transmission request414,416,418, and420. Then, when Node C calculates the interference cost for the first request response416, Node C needs to take into account the received power of only414(e.g., determining the interference cost to414because414is of higher priority than416, but418is of lower priority than416). However, when Node C calculates the interference cost for the second request response420, Node C needs to take into account the received power of both414and418(e.g., determining the interference cost to414as well as the interference cost to418because both414and418are of higher priority than420).

Evaluation module516can independently determine whether to transmit the first data traffic signal corresponding to the first request response and whether to send the second data traffic signal corresponding to the second request response. Evaluation module516may determine to transmit both data traffic signals, only one data traffic signal, or no data traffic signals. Even if the first transmission request may have higher priority than the second transmission request, evaluation module516may determine to send the second data traffic signal and not to send the first data traffic signal, as the second interference cost amount may be less than the first interference cost amount because of different beamforming vectors being utilized to determine the first and second interference cost amounts.

According to some aspects, it might be determined to transmit only the first data traffic signal if the recovered second request response signal is negative (e.g., the second request response signal is not successfully detected or recovered, because, for example, insufficient energy is received) or the estimated second interference cost amount is above a certain threshold. Coded modulation symbol creator520can generate a first set of coded modulation symbols from a first set of data information. Vector module522can apply the first beamforming vector to the first set of coded modulation symbols to generate the first data traffic signal, which can be sent by transmission module506in the channel resources of a traffic channel segment at the two antennas508,510.

Transmitter502can also include a measurement module524that is configured to calculate the first and second beamforming vectors for transmitting data traffic to receiver504prior to transmitting the first and second transmission request signals.

Additionally, system500can include memory526operatively coupled to transmitter502. Memory526can be external to transmitter502or can reside within transmitter502. Memory526can store information related to transmitting transmission request signals and receiving reply signals. Memory526can also store instructions related to recovering request response signals from the reply signals and determining whether to send data traffic signals. Additionally, memory526can store other suitable information related to signals transmitted and received in a communication network. A processor528can be operatively connected to transmitter502(and/or memory526) to facilitate analysis of information related to interference management in a communication network. Memory526can store protocols associated with interference management, taking action to control communication between receiver504and transmitter502, etc., such that system500can employ stored protocols and/or algorithms to achieve improved communications in a wireless network as described herein. Processor528can be a processor dedicated to analyzing and/or generating information received by transmitter502, a processor that controls one or more components of system500, and/or a processor that both analyzes and generates information received by transmitter502and controls one or more components of system500.

In view of the exemplary systems shown and described above, methodologies that may be implemented in accordance with the disclosed subject matter, will be better appreciated with reference to the following flow charts. While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of blocks, it is to be understood and appreciated that the claimed subject matter is not limited by the number or order of blocks, as some blocks can occur in different orders and/or at substantially the same time with other blocks from what is depicted and described herein. Moreover, not all illustrated blocks may be required to implement the methodologies described herein. It is to be appreciated that the functionality associated with the blocks may be implemented by software, hardware, a combination thereof or any other suitable means (e.g. device, system, process, component). Additionally, it should be further appreciated that the methodologies disclosed hereinafter and throughout this specification are capable of being stored on an article of manufacture to facilitate transporting and transferring such methodologies to various devices. Those skilled in the art will understand and appreciate that a methodology could alternatively be represented as a series of interrelated states or events, such as in a state diagram.

FIG. 6illustrates a method600of operating a first communication device for receiving data traffic from a second communication device in a peer-to-peer communication network, according to an aspect. The peer-to-peer communication network can be a MIMO network, wherein at least a subset of devices comprise at least two receive and transmit antennas. A processor executing instructions stored on a computer readable storage medium can be utilized to implement the various methods disclosed herein.

At602, a first signal and at least a second signal are received. These signals can be intended for first communication device and are received from second communication device, wherein a link is established between the devices. A channel matrix can be known a priori by the devices. The first signal and the second signal can be received in two distinct channel resources. One channel resource can correspond to at least one tone in an OFDM symbol.

At604, a first beamforming vector is applied to the first signal received at the two (or more) antennas in order to recover a first transmission request signal from second communication device. At606, a second beamforming vector is applied to the second signal received at the two (or more) antennas to recover a second transmission request signal from second communication device.

A determination is made, at608, whether to send at least one request response signal to second communication device in a subsequent request response time interval. If it is determined not to send a request response signal (“NO”), method600ends. If the determination is to send a request response signal (“YES”), at610, the at least one request response signal is transmitted to second device.

In accordance with some aspects, to determine, at608, whether to send one or more request response signals, interference amounts associated with each transmission request signal can be estimated. For example, a first interference amount associated with the first transmission request can be estimated and is indicative of the power of an interference to be seen by first device when first device utilizes a first beamforming vector to receive a data traffic from second device. A second interference amount associated with second transmission request can be estimated and is indicative of a power of an interference to be seen by first device when first device utilizes a second beamforming vector to receive data traffic from second device. The determination whether to send the at least one request response signal can depend on the estimated first interference amount, the second interference amount, or both the first interference amount and the second interference amount.

According to some aspects, the at least one request response signal can include a first request response signal that corresponds to the first transmission request signal. The first request response signal can be determined to be sent if the first interference amount is below a certain threshold. The first request response signal can be transmitted with a first beamforming vector.

In accordance with some aspects, method600can further recover an interfering transmission request signal in the transmission request time interval. The interfering transmission request signal can be a higher priority than the first transmission request signal from second device and the first interference amount can be estimated as a function of the power of the recovered interfering transmission request signal. According to some aspects, the interfering transmission request signal can be sent by a third device to a fourth device. The interfering transmission request signal indicates that third device intends to send a data traffic signal to fourth device and will interfere with the data traffic signal to be sent from second device to first device.

According to some aspects, the at least one request response signal can be determined to be sent if the first interference amount is below a certain threshold and if the second interference amount is below the certain threshold. In accordance with some aspects, method600can calculate a first and a second beamforming vector for receiving data traffic from the second device prior to receiving the signals at the two (or more) antennas in the transmission request time interval.

FIG. 7illustrates a method700for receiving data traffic at a first device, wherein the data traffic was sent by a second device, according to an aspect. Method700can include estimating interference amounts, at702, in order to determine whether to send at least one request response signal. According to some aspects, the at least one request response signal can include a first request response signal that corresponds to a first transmission request signal. The first request response signal can be determined to be sent if the first interference amount is below a certain threshold. A data traffic signal from the second device is received, at704, subsequent to transmitting the at least one request response signal. A first beamforming vector can be applied, at706, to the received data traffic signal to recover a first set of data information.

In accordance with some aspects, the at least one request response signal comprises a second request response signal that corresponds to a second transmission request signal. The second request response signal is determined to be sent if the second interference amount (estimated at702) is below a certain threshold. The second request response signal is transmitted with a second beamforming vector. The interfering transmission request signal can be a higher priority than the second transmission request signal from the second device and the second interference amount is estimated as a function of a power of the recovered interfering transmission request signal.

According to some aspects, at704, a data traffic signal is received from second device subsequent to transmitting at least one request response signal. The first beamforming vector can be applied to the received data traffic signal, at706, to recover a first set of data information. At708, the second beamforming vector can be applied to the received data traffic signal to recover a second set of data information.

FIG. 8illustrates a method800of operating a first communication device for transmitting data traffic to a second communication device in a multiple-input-multiple-output peer-to-peer communication environment, according to an aspect. The first communication device can be equipped with two or more antennas.

At802, a first transmission request signal with a first beamforming vector and a second transmission request signal with at least a second beamforming vector are transmitted. The first transmission request signal and the second transmission request signal are transmitted by the two or more antennas. In accordance with some aspects, the first and second transmission request signals are transmitted in two distinct channel resources, wherein one channel resource corresponds to at least one tone in an OFDM symbol.

In reply to the transmission request signals, in a subsequent request response time interval, signals are received, at804, at the two or more antennas. At806, at least one request response signal from second communication device is recovered from the received signals. The at least one request response signal corresponds to the first transmission request signal and the second transmission request signal. At808, a determination whether to send a data traffic signal to the second communication device is made as a function of the recovered request response signal. If the data traffic signal should be sent (“YES”) method800continues, at810and the data traffic signal is transmitted. If the data traffic signal should not be sent (“NO”), method800ends (or returns to806with another determination).

In accordance with some aspects, the received signals include a first signal and a second signal received in two distinct channel resources that respectively correspond to the distinct channel resources in which the first and second transmission request signals are transmitted. The at least one request response signal includes a first request response signal and a second request response signal that correspond to the first and second transmission request signals respectively. The first request response signal can be recovered by applying the first beamforming vector to the first received signal and the second request response signal can be recovered by applying the second beamforming vector to the second received signal.

Alternatively or additionally, method800includes calculating the first and second beamforming vectors for transmitting data traffic to second communication device before transmitting the first and second transmission request signals.

FIG. 9illustrates a method900for transmitting data traffic from a first device to a second device, according to an aspect At902, a first interference cost amount associated with a first transmission request signal and a second interference cost amount associated with a second transmission request signal are estimated. A determination whether to send the data traffic signals (e.g., element808ofFIG. 8) depends on at least one of the estimated first and second interference cost amounts. It can be determined to transmit a first data traffic signal if the recovered first request response signal is positive and the estimated first interference cost amount is below a certain threshold. The recovered first request response signal is positive if the power of the recovered first request response signal exceeds a threshold.

Method900can continue, at904, when a first set of coded modulation symbols is generated from a first set of data information. A first beamforming vector is applied, at906, to the first set of coded modulation symbols to generate the first data traffic signal. At908, the first data traffic signal is transmitted in the channel resources of a traffic channel segment at two or more antennas.

In accordance with some aspects, method900continues, at910, when a second set of coded modulation symbols is generated from a second set of data information. A second beamforming vector is applied, at912, to the second set of coded modulation symbols to generate the second data traffic signal. At914, the second data traffic signal is transmitted at the at least two antennas. The second data traffic signal is transmitted in the channel resources of the same traffic segment as the first data traffic signal.

FIG. 10illustrates a method1000for transmitting data traffic between a first device and a second device, according to an aspect. In accordance with some aspects, at1002, it is determined to transmit a first data traffic signal. The first data traffic signal might be sent if a recovered first request response signal is positive and an estimated first interference cost amount is below a certain threshold.

At1004, an interfering request response signal is received at the two or more antennas. The interfering request response signal is received in the request response time interval. The interfering transmission request signal might be a higher priority than a first request response signal received from the second device. A beamforming vector is applied, at1006, to the received interfering request response signal to obtain a first resultant signal. The first interference cost amount is estimated as a function of the power of the first resultant signal.

In accordance with some aspects, the interfering request response signal is sent by a third device to a fourth device. The interfering request response signal indicates that third device intends to receive a data traffic signal from fourth device and will be interfered by the data traffic signal to be sent from first device to second device. According to some aspects the first interference cost amount is indicative of a power of an interference to be seen by third device when first device transmits a data traffic to second device using the first beamforming vector. The first interference cost amount can further be estimated as a function of the transmission power of the first transmission request signal.

Additionally, it can be determined, at1008to transmit a second data traffic signal if the recovered second request response signal is positive and the estimated second interference cost amount is below a certain threshold. At1010, an interfering request response signal is received at the at least two antennas in the request response time interval. The interfering transmission request signal could be a higher priority than the second request response signal from the second device.

At1012, a second beamforming vector is applied to the received interfering request response signal to obtain a second resultant signal. The second interference cost amount can be estimated as a function of the power of the second resultant signal. According to some aspects, the second interference cost amount can further be estimated as a function of the transmission power of the second transmission request signal.

In accordance with some aspects, it might be determined to transmit only the first data traffic signal. This determination can be made if the recovered second request response signal is negative or the estimated second interference cost amount is above a certain threshold. In this case, method1000can generate a first set of coded modulation symbols from a first set of data information and apply the first beamforming vector to the first set of coded modulation symbols to generate the first data traffic signal. The first data traffic signal is transmitted in the channel resources of a traffic channel segment at the at least two antennas.

FIG. 11illustrates an example wireless terminal (e.g., mobile device, transmitting device, receiving device, and so forth)1100, which can be used as any one of the wireless terminals (e.g., mobile devices, transmitting device, receiving device, and so on) described herein. According to various aspects, wireless terminal1100facilitates selection of a multiple antenna scheme for data exchange in a communications network as a function of network conditions. Wireless terminal1100includes a receiver1102that includes a decoder1104, a transmitter1106that includes an encoder1108, a processor1110, and a memory1112which are coupled together by a bus1114over which the various elements1102,1106,1110,1112can interchange data and information. An antenna1116used for receiving signals from a transmitting device is coupled to receiver1102. An antenna1118used for transmitting signals (e.g., to a receiving device, to a peer node) is coupled to transmitter1106. Processor1110(e.g., a CPU) controls operation of wireless terminal1100and implements methods by executing routines1120and using data/information1122in memory1112.

Data/information1122includes user data1124, user information1126, and tone subset allocation sequence information1128. User data1124can include data, intended for a peer node, which will be routed to encoder1108for encoding prior to transmission by transmitter1106, and data received from a peer node, which has been processed by decoder1104in receiver1102. User information1126includes uplink channel information1130and downlink channel information1132. Uplink channel information1130includes information identifying uplink channels segments that have been assigned for wireless terminal1100to use when transmitting information. Uplink channels can include uplink traffic channels, dedicated uplink control channels (e.g., request channels, power control channels and timing control channels). Each uplink channel includes one or more logic tones, each logical tone following an uplink tone hopping sequence. The uplink hopping sequences are different between each sector type of a cell and between adjacent cells. Downlink channel information1132includes information identifying downlink channel segments that have been assigned to wireless terminal1100for use when receiving data/information. Downlink channels may include downlink traffic channels and assignment channels, each downlink channel including one or more logical tone, each logical tone following a downlink hopping sequence, which is synchronized between each sector of the cell.

User information1126also includes terminal ID information1134, which is an assigned identification, base station ID information1136, which identifies the specific base station that wireless terminal1100might have established communications with, and sector ID info1138, which identifies the specific sector of the cell where wireless terminal1100is presently located. Base station ID1136provides a cell slope value and sector ID info1138provides a sector index type; the cell slope value and sector index type may be used to derive tone hopping sequences. Mode information1140, also included in user information1126, identifies whether the wireless terminal1100is in sleep mode, hold mode, on mode, and so forth.

Tone subset allocation sequence information1128includes downlink strip-symbol time information1142and downlink tone information1144. Downlink strip-symbol time information1142includes frame synchronization structure information, such as the superslot, beaconslot, and ultraslot structure information and information specifying whether a given symbol period is a strip-symbol period, and if so, the index of the strip-symbol period and whether the strip-symbol is a resetting point to truncate the tone subset allocation sequence used by the base station. Downlink tone info1144includes information including a carrier frequency assigned to the base station, the number and frequency of tones, and the set of tone subsets to be allocated to the strip-symbol periods, and other cell and sector specific values such as slope, slope index and sector type.

Routines1120include communications routines1146and wireless terminal control routines1148. Communications routines1146control the various communications protocols used by wireless terminal1100. For example, communications routines1146can enable communicating through a wide area network and/or a local area peer-to-peer network (e.g., directly with disparate wireless terminal(s)). By way of further example, communications routines1146can enable receiving a broadcast signal. Wireless terminal control routines1148control basic wireless terminal1100functionality including the control of the receiver1102and transmitter1106.

Routines1120can also include data traffic communication routines1150. Data traffic communication routines1150can selectively transmit and/or receive data traffic from a peer device. For transmitting data traffic, data traffic communication routines1150can transmit a first transmission request signal with a first beamforming vector and a second transmission request signal with a second beamforming vector. Signals can be received (at two or more antennas) in a subsequent request response time interval and at least one request response signal can be recovered from the received signals. As a function of the recovered request response signal, a determination whether to send a data traffic signal can be made.

For receiving data traffic, data traffic communication routines1150can include receiving a first and a second signal (at two or more antennas) in a transmission request time interval. A first beamforming vector is applied to the first signal to recover a first transmission request signal and a second beamforming vector is applied to the second signal to recover a second transmission request signal. In a subsequent request response time interval one or more request response signals can be transmitted, if it is determined to send the request response signals.

With reference toFIG. 12, illustrated is a system1200that manages interference in a MIMO peer-to-peer network, according to an aspect. System1200can reside at least partially within a mobile device. It is to be appreciated that system1200is represented as including functional blocks, which may be functional blocks that represent functions implemented by a processor, software, or combination thereof (e.g., firmware).

System1200includes a logical grouping1202of electrical components that can act separately or in conjunction. Logical grouping1202can include an electrical component1204for receiving signals from a second communication device at two or more antennas of mobile device. Received signals can include a first signal and a second signal that are received in a transmission request time interval. In accordance with some aspects, the first signal and the second signal are received in two distinct channel resources. One channel resource corresponds to at least one tone in an OFDM symbol.

Also included in logical grouping1202is an electrical component1206for applying a first beamforming vector to the first signal to recover a first transmission request signal. Also included is an electrical component1208for applying a second beamforming vector to the second signal to recover a second transmission request signal.

Further, logical grouping1202includes an electrical component1210for determining whether to send at least one request response signal to the second communication device in a subsequent request response time interval. Also included is an electrical component1212for transmitting the at least one request response signal to the second communication device if it is determined to send the request response signals.

In accordance with some aspects, logical grouping1202includes an electrical component1214for estimating a first interference amount and a second interference amount. The first interference amount is associated with the first transmission request signal and the second interference amount is associated with the second transmission request signal. Electrical component1210for determining whether to sent the at least one response signal can make the determination as a function of the estimated first interference amount, the estimated second interference amount, or combinations thereof.

According to some aspects, logical grouping1202includes an electrical component1216for recovering an interfering transmission request signal in the transmission request time interval. The interfering transmission request signal can be a higher priority than the first transmission request signal from the second device. Further, the first interference amount is estimated as a function of the power of the recovered interfering transmission request signal. The interfering transmission request signal can be sent from a third device to a fourth device.

In accordance with some aspects, electrical component1204for receiving signals can receive a data traffic signal after electrical component1212for transmitting sends the at least one request response signal. Electrical component1206for applying the first beamforming vector applies the first beamforming vector to the received data traffic signal to recover a first set of data information.

According to another aspect, electrical component1204receives a data traffic signal after electrical component1212transmits at least one request response signal. Electrical component1206applies the first beamforming vector to the received data traffic signal to recover a first set of data information. Further, electrical component1208applies the second beamforming vector to the received data traffic signal to recover a second set of data information.

Further, in accordance with some aspects, logical grouping1202includes an electrical component1218for calculating a first and a second beamforming vectors for receiving data traffic from the second device before electrical component1204receives the signals at the two antennas in the transmission request time interval.

Additionally, system1200can include a memory1220that retains instructions for executing functions associated with electrical components1204-1218. While shown as being external to memory1220, it is to be understood that one or more of electrical components1204-1218can exist within memory1220.

FIG. 13illustrates a system1300that manages interference, according to an aspect. System1300can reside at least partially within a mobile device. It is to be appreciated that system1300is represented as including functional blocks, which can be functional blocks that represent functions implemented by a processor, software, or combination thereof (e.g., firmware).

System1300includes a logical grouping1302of electrical components that can act separately or in conjunction. Included in logical grouping1302is an electrical component1304for transmitting a first transmit request signal with a first beamforming vector and at least a second transmit request signal with at least a second beamforming vector. The first and second transmission request signals are transmitted by two or more antennas associated with mobile device. Also included is an electrical component1306for receiving signals at the two or more antennas in a subsequent request response time interval.

Logical grouping1302also includes an electrical component1308for recovering from the received signals at least one request response signal, which corresponds to the first transmission request signal and the second transmission request signal. Also included is an electrical component1310for ascertaining whether to send a data traffic signal as a function of the recovered request response signal and an electrical component1312for transmitting the data traffic signal if it is determined to send the data traffic signal. The wireless communications apparatus of claim50, wherein the first transmission request signal and the second transmission request signal are transmitted in two distinct channel resources, one channel resource corresponds to at least one tone in an OFDM symbol.

In accordance with some aspects, the received signals include a first signal and a second signal received in two distinct channel resources that respectively correspond to the distinct channel resources in which the first and second transmission request signals are transmitted. According to some aspects, one channel resource can corresponds to at least one tone in an OFDM symbol. The at least one request response signal includes a first and a second request response signals that correspond to the first and second transmission request signals respectively. The first request response signal is recovered by applying the first beamforming vector to the first received signal and the second request response signal is recovered by applying the second beamforming vector to the second received signal.

In accordance with some aspects, logical grouping includes an electrical component1314for estimating interference costs. A first interference cost amount is associated with the first transmission request signal and a second interference cost amount is associated with the second transmission request signal.

Alternatively or additionally, logical grouping can include an electrical component1316for generating coded modulation symbols and an electrical component1318for generating data traffic signals. Electrical component1316can generate a first set of coded modulation symbols from a first set of data information and electrical component1318can apply a first beamforming vector to the first set of coded modulation symbols to generate a first data traffic signal. Electrical component1312can transmit the first data traffic signal in the channel resources of a traffic channel segment at the at least two antennas.

Further, electrical component1316can generate a second set of coded modulation symbols for a second set of data information and electrical component1318can apply the second beamforming vector to the second set of coded modulation symbols to generate a second data traffic signal. Electrical component1312can transmit the second data traffic signal at the at least two antennas. The second data traffic signal can be transmitted in the channel resources of the same traffic channel segment as the first data traffic signal.

In accordance with some aspects, electrical component1304receives an interfering request response signal at the at least two antennas in the request response time interval. The interfering transmission request signal can be a higher priority than the first request response signal. An electrical component1320for obtaining resultant signals can apply the beamforming vector to the received interfering request response signal to obtain a first resultant signal. The first interference cost amount is estimated as a function of the power of the first resultant signal.

According to some aspects, electrical component1304receives an interfering request response signal at the at least two antennas in the request response time interval. The interfering transmission request response signal can be a higher priority than the second request response signal. Electrical component1320applies the second beamforming vector to the received interfering request response signal to obtain a second resultant signal. The second interference cost amount is estimated as a function of the power of the second resultant signal.

In accordance with another aspect, it can be determined to transmit only the first data signal if the recovered second request response signal is negative or the estimated second interference cost amount is above a certain threshold. In this case, electrical component1316generates a first set of coded modulation symbols from a first set of data information. Electrical component1318applies the first beamforming vector to the first set of coded modulation symbols to generate the first data traffic signal and electrical component1312transmits the first data traffic signal in the channel resources of a traffic channel segment at the at least two antennas.

Alternatively or additionally, logical grouping1302includes an electrical component1322for calculating the first and the second beamforming vectors for transmitting data traffic before electrical component1312transmits the first and the second transmission request signals.

Additionally, system1300can include a memory1324that retains instructions for executing functions associated with electrical components1304-1324or other components. While shown as being external to memory1324, it is to be understood that one or more of electrical components1304-1324may exist within memory1324.

Referring now toFIG. 14, illustrated is a wireless communication system1400in accordance with various aspects. System1400comprises a base station1402that can include a transmitter chain and a receiver chain, each of which can in turn comprise a plurality of components associated with signal transmission and reception (e.g., processors, modulators, multiplexers, demodulators, demultiplexers, antennas, and so forth), as will be appreciated by one skilled in the art. Additionally, base station1402can be a home base station, a Femto base station, and/or the like.

Base station1402can communicate with one or more devices such as device1404; however, it is to be appreciated that base station1402can communicate with substantially any number of devices. As depicted, device1404is equipped with multiple antennas, such as antennas1406and1408, where antennas1406and1408transmit information to base station1402over a reverse link1410and receive information from base station1402over a forward link1412. In a frequency division duplex (FDD) system, forward link1412can utilize a different frequency band than that used by reverse link1410, for example. Further, in a time division duplex (TDD) system, forward link1412and reverse link1410can utilize a common frequency band.

In addition, devices1414and1416can be communicating with one another, such as in a peer-to-peer configuration. Moreover, device1414and1416are equipped with multiple antennas are in communication using links1418and1420. In a peer-to-peer ad hoc network, devices within range of each other, such as devices1414and1416, communicate directly with each other without a base station1402and/or a wired infrastructure to relay their communication. Additionally, peer devices or nodes can relay traffic. The devices within the network communicating in a peer-to-peer manner can function similar to base stations and relay traffic or communications to other devices, functioning similar to base stations, until the traffic reaches its ultimate destination. The devices can also transmit control channels, which carry information that can be utilized to manage the data transmission between peer nodes.

A communication network can include any number of devices or nodes that are in wireless (or wired) communication. Each node can be within range of one or more other nodes and can communicate with the other nodes or through utilization of the other nodes, such as in a multi-hop topography (e.g., communications can hop from node to node until reaching a final destination). For example, a sender node may wish to communicate with a receiver node. To enable packet transfer between sender node and receiver node, one or more intermediate nodes can be utilized. It should be understood that any node can be a sender node and/or a receiver node and can perform functions of either sending and/or receiving information at substantially the same time (e.g., can broadcast or communicate information at about the same time as receiving information) or at different times.

FIG. 15illustrates an exemplary wireless communication system1500, according to various aspects. Wireless communication system1500depicts one base station and one terminal for sake of brevity. However, it is to be appreciated that system1500can include more than one base station or access point and/or more than one terminal or user device, wherein additional base stations and/or terminals can be substantially similar or different from the exemplary base station and terminal described below. In addition, it is to be appreciated that the base station and/or the terminal can employ the systems and/or methods described herein to facilitate wireless communication there between.

Referring now toFIG. 15, on a downlink, at access point1505, a transmit (TX) data processor1510receives, formats, codes, interleaves, and modulates (or symbol maps) traffic data and provides modulation symbols (“data symbols”). A symbol modulator1515receives and processes the data symbols and pilot symbols and provides a stream of symbols. A symbol modulator1515multiplexes data and pilot symbols and obtains a set of N transmit symbols. Each transmit symbol may be a data symbol, a pilot symbol, or a signal value of zero. The pilot symbols may be sent continuously in each symbol period. The pilot symbols can be frequency division multiplexed (FDM), orthogonal frequency division multiplexed (OFDM), time division multiplexed (TDM), frequency division multiplexed (FDM), or code division multiplexed (CDM).

A transmitter unit (TMTR)190receives and converts the stream of symbols into one or more analog signals and further conditions (e.g., amplifies, filters, and frequency upconverts) the analog signals to generate a downlink signal suitable for transmission over the wireless channel. The downlink signal is then transmitted through an antenna195to the terminals. At terminal1530, an antenna1535receives the downlink signal and provides a received signal to a receiver unit (RCVR)1540. Receiver unit1540conditions (e.g., filters, amplifies, and frequency downconverts) the received signal and digitizes the conditioned signal to obtain samples. A symbol demodulator1545obtains N received symbols and provides received pilot symbols to a processor1550for channel estimation. Symbol demodulator1545further receives a frequency response estimate for the downlink from processor1550, performs data demodulation on the received data symbols to obtain data symbol estimates (which are estimates of the transmitted data symbols), and provides the data symbol estimates to an RX data processor1555, which demodulates (i.e., symbol demaps), deinterleaves, and decodes the data symbol estimates to recover the transmitted traffic data. The processing by symbol demodulator1545and RX data processor1555is complementary to the processing by symbol modulator1515and TX data processor1510, respectively, at access point1505.

On the uplink, a TX data processor1560processes traffic data and provides data symbols. A symbol modulator1565receives and multiplexes the data symbols with pilot symbols, performs modulation, and provides a stream of symbols. A transmitter unit1570then receives and processes the stream of symbols to generate an uplink signal, which is transmitted by the antenna1535to the access point1505.

At access point1505, the uplink signal from terminal1530is received by the antenna195and processed by a receiver unit1575to obtain samples. A symbol demodulator1580then processes the samples and provides received pilot symbols and data symbol estimates for the uplink. An RX data processor1585processes the data symbol estimates to recover the traffic data transmitted by terminal1530. A processor1590performs channel estimation for each active terminal transmitting on the uplink.

Processors1590and1550direct (e.g., control, coordinate, manage, . . . ) operation at access point1505and terminal1530, respectively. Respective processors1590and1550can be associated with memory units (not shown) that store program codes and data. Processors1590and1550can also perform computations to derive frequency and impulse response estimates for the uplink and downlink, respectively.

For a multiple-access system (e.g., FDMA, OFDMA, CDMA, TDMA, and the like), multiple terminals can transmit concurrently on the uplink. For such a system, the pilot subbands may be shared among different terminals. The channel estimation techniques may be used in cases where the pilot subbands for each terminal span the entire operating band (possibly except for the band edges). Such a pilot subband structure would be desirable to obtain frequency diversity for each terminal. The techniques described herein may be implemented by various means. For example, these techniques may be implemented in hardware, software, or a combination thereof. For a hardware implementation, the processing units used for channel estimation may be implemented within one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field programmable gate arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, other electronic units designed to perform the functions described herein, or a combination thereof With software, implementation can be through modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in memory unit and executed by the processors1590and1550.

For a software implementation, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in memory units and executed by processors. The memory unit may be implemented within the processor or external to the processor, in which case it can be communicatively coupled to the processor through various means as is known in the art. Further, at least one processor may include one or more modules operable to perform the functions described herein.

Single carrier frequency division multiple access (SC-FDMA), which utilizes single carrier modulation and frequency domain equalization is a technique that can be utilized with the disclosed aspects. SC-FDMA has similar performance and essentially a similar overall complexity as those of OFDMA system. SC-FDMA signal has lower peak-to-average power ratio (PAPR) because of its inherent single carrier structure. SC-FDMA can be utilized in uplink communications where lower PAPR can benefit a mobile terminal in terms of transmit power efficiency.

While the foregoing disclosure discusses illustrative aspects and/or aspects, it should be noted that various changes and modifications could be made herein without departing from the scope of the described aspects and/or aspects as defined by the appended claims. Accordingly, the described aspects are intended to embrace all such alterations, modifications and variations that fall within scope of the appended claims. Furthermore, although elements of the described aspects and/or aspects may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. Additionally, all or a portion of any aspect and/or aspect may be utilized with all or a portion of any other aspect and/or aspect, unless stated otherwise.

To the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim. Furthermore, the term “or” as used in either the detailed description or the claims is intended to mean an inclusive “or” rather than an exclusive “or”. That is, unless specified otherwise, or clear from the context, the phrase “X employs A or B” is intended to mean any of the natural inclusive permutations. That is, the phrase “X employs A or B” is satisfied by any of the following instances: X employs A; X employs B; or X employs both A and B. In addition, the articles “a” and “an” as used in this application and the appended claims should generally be construed to mean “one or more” unless specified otherwise or clear from the context to be directed to a singular form.