DE112008002055B4 - Channel-aware multi-user MIMO scheme unified with single-user closed-loop MIMO - Google Patents

Abstract

A method comprising: in an uplink transmission, receiving rank-1 channel quality indicator values from one or more subscriber terminals, the channel quality indicator values being based, at least in part, on channel information; in an uplink transmission, receiving two or more vectors from the one or more subscriber stations; Determining which of the one or more subscriber stations has a best rank-1 channel quality indicator value; Determining a beamforming matrix based at least in part on the two or more vectors received from the subscriber station having the best rank-1 channel quality indicator value; and in a downlink transmission, broadcasting to the one or more subscriber stations using the beamforming matrix corresponding to the subscriber station having the best ranked 1-channel quality indicator; and in an uplink transmission, receiving rank 2 channel quality indicator values from the one or more sub-terminal stations; if the rank 1 channel quality indicator value is greater than the rank 2 channel quality indicator values of individual subscriber stations or greater than the rank 2 channel quality indicator values of multiple subscriber stations, then: selecting a single-user multiple-input, multiple-output ) Rank-1 mode for data transmission; and ...

Description

BACKGROUND

Multiple user-multiple-input, multiple-output (MU-MIMO) schemes have received increasing attention in recent years as MU-MIMO can provide both multi-user diversity and spatial diversity. The capacity of MU-MIMO can be much higher than single-user MIMO (SU-MIMO), especially for example when the antenna configuration is asymmetric, for example in a 4 × 2 array or a 2 × 1 Arrangement, be. An asymmetric configuration may occur when a base station (BS) has a larger number of transmit (Tx) antennas than the number of receive (Rx) antennas at the subscriber station (SS )) or in a channel state with high correlation. MU-MIMO differs from SU-MIMO in that MU-MIMO can be associated with transmitting transmission streams for multiple users in a transmitting functional unit.

"Samsung:" Dynamic Switching between Single and Multi-User MIMO "discloses a method which, in uplink transmission, receiving rank-1 channel quality indicator values from one or more subscriber stations, the channel quality indicator values being based at least in part on channel information, Determining which of the one or more subscriber stations has a best rank-1 channel quality indicator value and determining a beamforming matrix.

"Texas Instruments: UE Feedback Mechanism To Support Single-User & Multiuser MIMO" "discloses CQI values as well as the feedback of a preferred range and index for precoding from a subscriber station to a base station.

"Nokia, Nokia Siemens Networks:" LTE Multiuser MIMO and Interference Suppression in the UE "refers to a MU-MIMO transmission for LTE and reveals that system capacity can be increased if a receiver has information about the interference from other subscribers , Therefore, it is proposed there to signal the used Vorkodierungsvektoren and thus the beam-forming matrix to the mobile subscribers, including those of the other participants.

The present invention provides a method according to claim 1, an article of manufacture comprising a storage medium with instructions stored thereon according to claim 8 and a base station according to claim 15.

The dependent claims relate to advantageous developments of the same.

DESCRIPTION OF THE FIGURES

The claimed subject matter is particularly pointed out and distinctly claimed in the summary of the specification. However, said subject matter may be understood by reference to the following detailed description taken in conjunction with the accompanying drawings, in which:

1 shows a block diagram of a MU-MIMO system according to one or more embodiments;

2 12 shows a diagram of a multi-stream, channel-aware MU-MIMO transmission scheme according to one or more embodiments;

3 Fig. 12 shows a diagram of a MU-MIMO transmission scheme using feedback (channel quality indicator and vector (CQI / V)) without downsampling according to one or more embodiments;

4 Figure 12 shows a diagram of a MU-MIMO transmission scheme using feedback of a channel quality indicator and vector (CQI / V) with downsampling according to one or more embodiments; and

5 FIG. 3 shows a flow diagram of a method for merging a multi-user MIMO scheme with a single-user MIMO scheme, according to one or more embodiments.

It will be understood that for the sake of simplicity and / or clarity of illustration, elements shown in the figures are not necessarily drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for the sake of clarity. When properly considered, reference numerals have been repeated in the figures to indicate corresponding and / or analogous elements.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the claimed subject matter. However, it will be understood by those skilled in the art that the claimed subject matter may be practiced without these specific details. In other For example, well-known methods, procedures, components, and / or circuits have not been described in detail.

In the following description and / or claims, the terms "coupled" and / or "connected", along with their derivatives, may be used. In particular embodiments, "connected" may be used to indicate that two or more elements are in direct physical and / or electrical contact with each other. "Coupled" may mean that two or more elements are in direct physical and / or electrical contact. But "coupled" can also mean that two or more elements are not in direct contact with each other but still work together and / or interact with each other unchanged. For example, "coupled" may mean that two or more elements are not in contact with each other but are indirectly connected to each other via another element or elements. Finally, the terms "on," "overlying," and "over," may be used in the following description and in the claims. "Up," "overlying" and "over" can be used to indicate that two or more elements are in direct physical contact with each other. However, "over" may also mean that two or more elements are not in direct contact with each other. For example, "over" may mean that one element is disposed over another element but can not contact one another and another element or elements may be present between the two elements. In addition, the term "and / or" "and" may mean, "or" mean, "excluding or" meaning "one (1)" meaning "some but not all" meaning "none" and / or " both mean "although the scope of the claimed subject matter is not limited in this respect. In the following description and / or claims, the terms "comprising" and "including" together with their derivatives may be used as synonyms for each other and so provided.

With reference to 1 A block diagram of a MU-MIMO system according to one or more embodiments will now be discussed. As in 1 shown is the MIMO system 100 a base station (Base Station (BS)) 110 and one or more Subscriber Stations (SS) 114 comprising a first subscriber station (SS ₁ ), a second subscriber station (SS ₂ ), up to N subscriber stations (SS _N ), one or more of the subscriber stations 114 with the base station 110 can communicate wirelessly. In such a MIMO system 100 can the base station 110 several antennas 112 include and can the respective subscriber stations 114 equally one or more antenna (s) 116 . 118 and or 120 exhibit. It should be known that the number of one or more subscriber stations 114 may have their own number of antennas, for example when the number of antennas 116 the first subscriber station SS ₁ other than the number of antennas 118 the second subscriber station 552 which may both be different than the number of antennas of an Nth subscriber station SS _N. Similarly, one or more of the subscriber stations 114 a different number of antennas than the number of antennas 112 the base station, although in some cases one or more of the base stations 110 and one or more of the subscriber stations 114 may have the same number of antennas, and the scope of the claimed subject matter is not limited in this respect. It should also be noted that the model is base station 110 and subscriber station 114 , this in 1 only one example of an arrangement of the MIMO system is shown 100 and, in one or more alternative embodiments, the base station 110 even a subscriber station 114 may be and / or one or more of the subscriber stations 114 with another or more of the subscriber stations 114 can communicate directly, for example in an ad hoc network arrangement or the like, and the scope of the claimed subject matter is not limited in this respect.

In one or more embodiments, the communication between the base station 110 and one or more of the subscriber stations 114 associated with precoding, spatial multiplexing and / or diversity encoding, singly or in combination. Furthermore, the base station 110 with one of the subscriber stations 114 communicate directly by sending all their antenna resources to the respective subscriber station 114 For example, to achieve higher data rates, or alternatively, the base station 110 some of their antenna resources to one or more subscriber stations 114 for example, serving a larger number of subscriber stations 114 to optimize. In one or more embodiments, which will be discussed herein, the MIMO system may 100 Implement a channel aware multi-user MIMO (Channel Aware Multi-User MIMO (CA-MU-MIMO)) system. In such a channel aware MIMO system 100 For example, a precoding vector and / or the codebook index may be based, at least in part, on a feedback made by one or more users, such as one or more of the subscriber stations 114 is received, be channel aware (channel aware). In one or more embodiments, channel quality indicators (Channel Quality Indicators (CQIs)), which correspond to selected precoding vectors, to the base station 110 for user scheduling (user scheduling) of the subscriber stations 114 in the base station 110 returned. The user time control in the base station 110 may be based on one or more principles, for example, user orthogonality, or the maximization of proportional fairness metric and so forth. In one or more particular embodiment (s), two types of CQIs, for example Rank-1 (Rank-1) and Rank-2 (Rank-2), may be used for MIMO rank / mode adaptation. Interference unaware rank-1 CQIs can be used to select the pre-coding vector, and interference-inaware rank-2 CQIs can be used for MIMO rank / link / mode adaptation and user selection. By using the same codebook as used in a single-user closed-loop (MIMO) single-user closed-loop scheme, this can be done by the MIMO system 100 Implemented channel-aware MU-MIMO scheme can be unified with a closed single-user MIMO scheme. Such a MU-MIMO scheme will be described with reference to 2 . 3 and 4 discussed in more detail below.

With reference to 2 Now, a diagram of a multi-stream channel aware MU-MIMO transmit scheme will be discussed according to one or more embodiments. In the in 2 shown channel-conscious MU-MIMO scheme 200 can be a broadcasting procedure by the base station 110 can be implemented, for several streams, such as a 2 x 2 array with two streams, look like this. One should note that the 2 × 2 nomenclature applies to the base station 110 refers to the two antennas for transmission to a subscriber station 114 used, which uses two antennas for receiving. In short, the send procedure may include a channel aware MU-MIMO procedure with CQI and vector return. The subscriber station 114 Can Single Value Decomposition (SVD) of All User Channels in Second to Last Subframe 214 of the i-th frame 212 perform the beamforming vectors for each subscriber station 114 to obtain. Then enter the subscriber stations 114 a rank 1 CQI to the base station 110 back. In addition, each of the subscriber stations 114 their respective two main vectors to the base station 110 hand back. The base station 110 then determines the selected beamforming vectors, which in the 2x2 case comprise two vectors, from the subscriber station 114 with the best Rank 1 CQI score. The base station 110 can then in the last subframe 216 of the i-th frame 210 the selected vectors from the subscriber station 114 with the best Rank 1 CQI value to all subscriber stations 114 broadcast. Then, each subscriber station calculates for rank 2 CQI return in the last subframe 216 of the i-th frame 216 the rank 2 CQIs, which in this case may include two rank 2 CQIs, by using those from the base station 110 received broadcast vectors. The subscriber stations 114 can then calculate two CQIs to the base station 110 hand back. Upon receipt, the base station can 110 based on timing criteria and / or MIMO mode / rank according to rank-1 / rank-2 CQIs that the base station 110 from subscriber stations 114 has to identify the pairing users. If the rank 1 mode or the same user is assigned two streams over the same resource block (RB), then the base station may 110 select to use single-user MIMO transmission. Otherwise, multi-user transmission is selected.

In one or more embodiments, a more detailed broadcasting procedure may be for the channel-aware MU-MIMO scheme 200 from 2 look like this. In the second to last subframe 214 of the i-th frame 210 gives each participant station 114 a rank 1 CQI value to the base station 110 for the uplink (UL) transmission of subscriber stations 114 to the base station 110 for the rank adaptation based on the channel information for itself on which the SVD decomposition can be based. In the Rank 1 CQI calculation, there is no interference resulting from the second stream. Each subscriber station thereafter outputs its two main vectors, or beamforming matrix, from their respective SVD decomposition via their own channel matrix to the base station 110 back.

Next, compare the base station 110 in the last subframe 216 of the i-th frame 210 for the downlink (DL) transmission from the base station 110 to the subscriber stations 114 all from each of the subscriber stations 114 received rank-1 CQIs and determines which of the subscriber stations 114 has the best Rank 1 CQI value. The base station 110 can then determine a selected beamforming matrix containing the two main beamforming vectors from the base station 114 with the best rank-1 CQI score. The base station 110 then sends the selected beamforming matrix to all of the subscriber stations 114 in the MIMO system 100 round.

For the subsequent uplink transmission, each of the subscriber stations then calculates the rank 2 CQIs, which may include two rank 2 CQIs in the two stream case, by using the beamforming matrix vectors, in this case two vectors, and then send the two calculated CQIs to the base station 110 back. In one or According to several embodiments, the rank 2 CQIs may be determined using a minimum mean squared error (MMSE) receiver at the subscriber stations 114 can calculate. Each participant station 114 then returns two rank 2 CQIs to the base station 110 back to the user pairing.

Next, the base station 110 in the first subframe 218 of the (i + 1) th frame 212 , the next frame for the downlink transmission, the paired subscriber stations 114 based on timing criteria for MU-MIMO and / or based on MIMO-mode / rank according to the rank-1 / rank-2 CQIs preceding the subscriber stations 114 received, determine. The base station 110 can then begin to send data by using the precoding vectors as follows. If the value of the rank 1 CQI is greater than the single user rank 2 CQIs and / or the multi-user rank 2 CQIs, the base station selects 110 SU-MIMO Rank 1 mode for data transmission. In this case, the base station 110 a stream with the first vector from the broadcast beamforming matrix for the selected subscriber station 114 send. This selected subscriber station 114 corresponds to the highest order rank 1 CQI compared to the SU MIMO rank 2 CQIs and / or MU MIMO rank 2 CQIs.

Otherwise, the base station dials 110 in the case that the single-user rank 2 CQI is greater than the single-user rank-1 CQI and / or the multi-user rank-2 CQIs, the SU-MIMO rank 2 mode is for data transfer , In this case, the base station 110 two streams with the two vectors from the broadcast beamforming matrix for the selected subscriber station 114 send. This selected subscriber station 114 corresponds to the highest order SU rank 2 CQIs compared to the SU rank 1 CQI and / or MU rank 2 CQIs.

If none of the above comparisons are valid then the base station will otherwise dial 110 the MU MIMO rank 2 mode for data transmission. In this case, the base station 110 send two streams with the two beamforming vectors from the broadcast beamforming matrix for the selected two different subscriber stations. These two selected subscriber stations 114 will have the most significant MU rank 2 CQIs based on a summation over two different subscriber stations 114 , compared to the SU rank 1 CQI and / or the SU rank 2 CQIs.

In one or more embodiments, the channel-aware MU-MIMO scheme may 200 , this in 2 shown, to a larger number of streams, more than two streams, and a larger number of antenna configurations, for example, a 4 × 2 antenna configuration, in which the base station 110 may have four antennas and the subscriber stations 114 may have two antennas, or a 4 × 4 antenna configuration, where the base station 110 may have four antennas and the subscriber stations 114 four antennas, and so on, can be expanded. In such extensions, the difference may include the number of return beamforming vectors and CQIs used. In the higher number of antennas / antenna number configuration, there will be a corresponding return number for the beamforming vectors and CQIs. For example, in the case of four streams over a 4 × 4 antenna configuration, it will be four beamforming vectors for broadcasting and four CQIs for user pairing for multiple users in the MIMO system 100 give. However, these are merely examples of how multiple streams and / or larger numbers of antennas can be implemented, and the scope of the claimed subject matter is not limited in this respect.

With reference to 3 Now, a diagram of a MU-MIMO transmission scheme will be discussed using return of a channel quality indicator and vector (CQI / V) without downsampling according to one or more embodiments. In the channel-aware MU-MIMO scheme 300 from 3 No downsampling is used at the frame level. In a particular embodiment, the frame size is 5 milliseconds, although the scope of the claimed subject matter is not limited in this respect. As in 3 2, each subscriber station may be shown for each subframe 114 the same content to the base 110 for example, each subscriber station will return 114 return a CQI value based at least in part on the last channel information. Each participant station 114 the two rank 2 CQIs will be based, at least in part, on the broadcast two or more beamforming vectors generated by the base station 110 receive and then calculate the rank 2 CQIs to the base station 110 hand back.

In the next subframe becomes the base station 110 two new beamforming vectors from the subscriber stations 114 with the highest-grade rank-1 CQI for broadcasting. The base station 110 will send the data through the selected MIMO mode, either an SU-MIMO mode or a MU-MIMO mode, and use the selected beamforming vector to precode over the data. In one or more Embodiment (s) may include total band return in a subframe based at least in part on a Best-M algorithm for reducing the feedback overhead. The beamforming vector may also be used in conjunction with the CQI return based at least in part on a Best-M algorithm. Such an embodiment may be implemented via a stream line mode. Each subframe may have the same return overhead, and each subframe may implement switching between an SU-MIMO mode and a MU-MIMO mode, between rank-1 and rank-2, and so on, although the scope of protection of the claimed subject matter is not limited in this regard.

With reference to 4 Now, a diagram of a MU-MIMO transmission scheme using return of a channel quality indicator and vector (CQI / V) with downsampling in accordance with one or more embodiments will now be discussed. In the channel-aware MU-MIMO scheme 400 from 4 Downsampling can be used to return at the frame level. In one or more embodiments, the frame size 5 Milliseconds or more. The MU-MIMO scheme 400 from 4 is essentially similar to the MU-MIMO scheme 300 from 3 in which the difference may include the switching unit or a switching period. Any frame of 5 milliseconds or longer frames greater than 5 milliseconds will return the same content. For example, each subscriber station becomes 114 to return a CQI based, at least in part, on the most recent channel information. Each participant station 114 will calculate two rank 2 CQIs based, at least in part, on the transmitted two beamforming vectors, which thereafter go to the base station 110 be returned.

In the next frame of 5 ms or longer frames larger than 5 ms, the base station becomes 110 select two new beamforming vectors from the subscriber station with the most significant rank 1 CQI for broadcasting. The base station 110 will send the data via the selected MIMO mode, either SU-MIMO or MU-MIMO, and use the selected beamforming vector to precode over the data. Returning over the entire band in a frame of 5 ms or longer frames greater than 5 ms may be based, at least in part, on a Best-M algorithm to reduce the return overhead. The beamforming vector may also be used in conjunction with CQI return based at least in part on a Best-M algorithm. Such a case may be implemented via stream line mode. Each frame of 5 ms or longer frames greater than 5 ms will have the same return overhead, and each frame of 5 ms or longer frames longer than 5 ms may switch between SU-MIMO and MU-MIMO, between rank-1 and rank-2, and so on, although the scope of the claimed subject matter is not limited in this respect.

In one or more embodiments, a channel-aware MU-MIMO scheme may implement timing and / or hybrid automatic repeat request (HARQ) retransmission. User-driven control for channel-aware MU-MIMO may be based on user timing in the base station based at least in part on principles such as user orthogonality or maximizing proportional fairness metric, and so forth. In user control, the base station becomes 110 calculate the PF metric based at least in part on the SU rank 1, SU rank 2 and / or MU rank 2 CQIs and / or based at least in part on criteria to form a MIMO mode for the Select transmission. Then the user pairing can be determined.

For HARQ implemented in a channel aware MU-MIMO scheme, HARQ retransmission could be implemented as an asynchronous mode or a synchronous mode. A non-blanking / blanking (HARQ) mode could be used for a channel-aware MU-MIMO scheme where MU-MIMO will have two streams for transmission, even if the MIMO system 100 undergoes a retransmission. For example, in the case where two data streams are supported, in the case where two streams are transmitted for MU-MIMO, a stream with an error would retransmitted to the next transmission time. The other correct stream would be transmitted with new data at the next transmission time. The pre-coding vectors used for the new data and retransmission could be the latest beam-forming vectors from the MU-MIMO timing controller.

In one or more embodiments of MU-MIMO, mode / rank adaptation may be used to maintain link performance even if the channel is changed. The change mode could be implemented for both flexible and / or semi-static solutions. For the flexible adaptation mode, subscriber stations will return CQI values of all adaptable ranks / modes, and then the base station 110 collect all the information on the mode / rank determination. The change could be implemented on a frame by frame basis. Such a change mechanism may have sufficient performance with greater return overhead. For a semi-static adaptation subscriber stations 114 request an adaptation if a subscriber station 114 a channel change is noticed, and then the base station 110 decide on the needed adaptation. In such an arrangement, the frequency may change relatively slowly, but using a lower return overhead.

In one or more embodiments, the channel-aware MU-MIMO scheme may use the downlink transmission for pilot signal measurement and / or detection. Pilots may be implemented for measurement, for example, using a scattered common pilot, a midamble, reference signals to take out the MIMO CQI return, such as a Channel Quality Indicator (CQI), control sequence indicator ( Control Sequence Indicator (CSI)) and Power Margin Indicator (PMI), codebook index, etc. When pilots are used for demodulation, a channel-aware MU-MIMO scheme can use a dedicated pre-coded pilot for data detection to To save overhead, although the scope of the claimed subject matter is not limited in this respect.

With reference to 5 A flow diagram of a method of associating a multi-user MIMO scheme with a single-user MIMO scheme in accordance with one or more embodiments is discussed. The procedure 500 from 5 includes a particular order of a SU-MIMO and MU-MIMO scheme, however, the method may 500 other orders include and / or more or fewer blocks than in 5 and the scope of the claimed subject matter is not limited in this respect. At block 510 receives a base station 110 Rank 1 CQI scores from one or more participating states 114 that can generally be called a user. At block 512 receives the base station 110 two or more vectors from the respective subscriber stations corresponding to a beamforming matrix codebook. The base station 110 then determines at block 514 which the user has the best Rank 1 CQI value. The base station 110 then select the vectors corresponding to the user with the best Rank 1 CQI value at block 516 , Using the vectors from the user with the best Rank 1 CQI value, the base station transmits 110 the vectors to all the users at block 518 round. The users will then calculate rank 2 CQI values using the broadcast vectors and then return the rank 2 CQI values received at the base station 110 at block 520 be received. The base station 110 then determines user pairing based on at least in part the Rank 2 CQI values at block 522 by comparing the rank 1 and rank 2 values received from the subscriber stations 114 were obtained. When the base station 110 at block 524 determines if a rank 1 CQI value is the best of the CQI values, or if the same user is assigned two or more streams, then the base station selects 110 Single-user MIMO operation. Otherwise, if the base station at block 526 Determining two or more users who have the best rank 2 CQI scores selects the base station 110 Multi-user MIMO operation.

Although the claimed subject matter has been described with a degree of particularity, it is to be understood that elements thereof may be modified by those skilled in the art without departing from the spirit and / or scope of the claimed subject matter. It will be appreciated that the subject matter relating to a multi-user channel aware MIMO scheme unified with single user closed MIMO and / or many of its associated tools will be understood from the foregoing description, and it will be apparent that numerous changes can be made in the form, construction and / or arrangement of the components thereof without departing from the scope and / or spirit of the claimed subject matter or sacrificing all material advantages, the form hereinbefore described being merely an exemplary embodiment same and / or further without significant changes thereto. The claims are intended to cover and / or contain such changes.

Claims (17)

A method comprising: in an uplink transmission, receiving rank-1 channel quality indicator values from one or more subscriber terminals, the channel quality indicator values being based, at least in part, on channel information; in an uplink transmission, receiving two or more vectors from the one or more subscriber stations; Determining which of the one or more subscriber stations has a best rank-1 channel quality indicator value; Determining a beamforming matrix based at least in part on the two or more vectors received from the subscriber station having the best rank-1 channel quality indicator value; and in a downlink transmission, broadcasting using the beamforming matrix containing the subscriber station with the best rank-1 channel Quality indicator corresponds to the one or more subscriber stations; and in an uplink transmission, receiving rank 2 channel quality indicator values from the one or more sub-terminal stations; if the rank 1 channel quality indicator value is greater than the rank 2 channel quality indicator values of individual subscriber stations or greater than the rank 2 channel quality indicator values of multiple subscriber stations, then: selecting a single-user multiple-input, multiple-output ) Rank-1 mode for data transmission; and transmitting a data stream using the rank-1 vectors for beamforming corresponding to the subscriber station having the best rank-1 channel quality indicator value. The method of claim 1, further comprising: in an uplink transmission, receiving ranked 2 channel quality indicator values from the one or more subscriber stations; if a rank 2 channel quality indicator value is greater than a rank 1 channel quality indicator value from a single subscriber station or greater than a rank 2 channel quality indicator value from multiple subscriber stations, then: Selecting a single-user multiple-input, multiple-output-rank-2 mode for data transmission; and Transmitting two data streams using the beamforming matrix for the subscriber station with the best ranked 2 channel quality indicator value. The method of claim 1, further comprising: in an uplink transmission, receiving ranked 2 channel quality indicator values from the one or more subscriber stations; if two or more subscriber stations have the best Rank 2 channel quality indicator values, then: Selecting a multi-user, multiple-output, rank-2 mode for data transmission; and Transmitting two data streams using the beamforming matrices for the two or more subscriber stations having the best ranked 2 channel quality indicator value. A method according to claim 1, characterized in that the channel quality indicator values are based at least in part on a singular value decomposition. The method of claim 1, characterized in that the channel quality indicator values are based, at least in part, on an assumption of no interference between two or more streams. A method according to claim 1, characterized in that said receiving of rank 1 channel quality indicator values from one or more subscriber stations and receiving of rank 2 channel quality indicator values from the one or more subscriber stations in each subframe occurs. The method of claim 1, characterized in that the rank 1 channel quality indicator values from one or more subscriber stations and said receiving rank 2 channel quality indicator values from the one or more subscriber stations in each subframe based at least in part on one Best-M calculation takes place to reduce feedback from the one or more users. An article of manufacture comprising a storage medium having instructions stored thereon and resulting in execution: in an uplink transmission, receiving rank 1 channel quality indicator values from one or more subscriber stations, the channel quality indicator values being based, at least in part, on channel information; in an uplink transmission, receiving two or more vectors from the one or more subscriber stations; Determining which of the one or more subscriber stations has a best rank-1 channel quality indicator value; Determining a beamforming matrix based at least in part on the two or more vectors received from the subscriber station having the best ranked 1 channel quality indicator value; in a downlink transmission, broadcasting the beamforming matrix corresponding to the subscriber station having the best ranked 1 channel quality indicator to the one or more subscriber stations; and in an uplink transmission, receiving rank 2 channel quality indicator values from the one or more remote terminals; if a rank 1 channel quality indicator value is greater than the rank 2 channel quality indicator values of individual subscriber stations or greater than the rank 2 channel quality indicator values of multiple subscriber stations, then: Selecting a single-user multiple-input, multiple-output-rank-1 mode for data transmission; and Transmitting a data stream using the rank-1 vectors for beamforming corresponding to the subscriber station having the best rank-1 channel quality indicator value. The article of manufacture of claim 8, further comprising: in an uplink transmission, receiving ranked 2 channel quality indicator values from the one or more subscriber stations; if a rank 2-channel quality indicator value is greater than a rank-1 channel quality indicator value from a single subscriber station or greater than a rank-2 channel quality indicator value from multiple subscriber stations, then: selecting a single-user multiple-input, multiple-output output) rank 2 mode for data transmission; and transmitting two data streams using the beamforming matrix for the subscriber station having the best ranked 2-channel quality indicator value. The article of manufacture of claim 8, further comprising: in an uplink transmission, receiving ranked 2 channel quality indicator values from the one or more subscriber stations; if two or more subscriber stations have the best Rank 2 channel quality indicator values, then: Selecting a multi-user, multiple-output, rank-2 mode for data transmission; and Transmitting two data streams using the beamforming matrices for the two or more subscriber stations having the best ranked 2 channel quality indicator values. An article of manufacture according to claim 8, characterized in that the channel quality indicator values are based at least in part on a singular value decomposition. An article of manufacture according to claim 8, characterized in that channel quality indicator values are based, at least in part, on an assumption of no interference between two or more streams. An article of manufacture according to claim 8, characterized in that said receiving of rank 1 channel quality indicator values from one or more subscriber stations and receiving of rank 2 channel quality indicator values occurs from the one or more subscriber stations in each subframe. An article of manufacture according to claim 8, characterized in that said receiving of rank 1 channel quality indicator values from one or more subscriber stations and said receiving of rank 2 channel quality indicator values from the one or more subscriber stations in each subframe is at least in part on a best M calculation takes place to reduce feedback from the one or more users. Base station comprising: a radio frequency transceiver coupled to an antenna; and a baseband processor coupled to the radio frequency transceiver, the baseband processor capable of: in uplink transmission, receiving rank 1 channel quality indicator values from one or more subscriber stations, the channel quality indicator values being based, at least in part, on channel information; in an uplink transmission, receiving two or more vectors from the one or more subscriber stations; Determining which of the one or more subscriber stations has a best rank-1 channel quality indicator value; Determining a beamforming matrix based at least in part on the two or more vectors received from the subscriber station having the best ranked 1 channel quality indicator value; and in a downlink transmission, broadcasting the beamforming matrix corresponding to the subscriber station having the best ranked 1-channel quality indicator to the one or more subscriber stations; and in an uplink transmission, receiving rank 2 channel quality indicator values from the one or more remote terminals; if a rank 1 channel quality indicator value is greater than the rank 2 channel quality indicator values of individual subscriber stations or greater than the rank 2 channel quality indicator values of multiple subscriber stations, then: Selecting a single-user multiple-input, multiple-output-rank-1 mode for data transmission; and Transmitting a data stream using the rank-1 vectors for beamforming corresponding to the subscriber station having the best rank-1 channel quality indicator value. The base station of claim 15, characterized in that the baseband processor is further capable of: in uplink transmission, receiving rank 2 channel quality indicator values from the one or more subscriber stations; if a rank 2-channel quality indicator value is greater than a rank-1 channel quality indicator value from a single subscriber station or greater than a rank-2 channel quality indicator value from multiple subscriber stations, then: selecting a single-user multiple-input, multiple-output output) rank 2 mode for data transmission; and Transmitting two data streams using the beamforming matrix for the subscriber station with the best ranked 2 channel quality indicator value. The base station of claim 15, characterized in that the baseband processor is further capable of: in uplink transmission, receiving rank 2 channel quality indicator values from the one or more subscriber stations; if two or more subscriber stations have the best rank 2 channel quality indicator values, then: selecting a multi-user, multiple-output, rank-2 mode for data transmission; and transmitting two data streams using the beamforming matrices for the two or more subscriber stations having the best ranked 2 channel quality indicator values.

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