Method for non-iterative singular-value decomposition (SVD). The method includes receiving, by receiver, signal; determining, by channel matrix generator, channel matrix for received signal, where channel matrix has dimension N.sub.rx?N.sub.tx, N.sub.rx is number of receive antennas, N.sub.tx is integer indicating number of transmit antennas; reducing, by singular-value decomposer, dimension of channel matrix to min(N.sub.rx,N.sub.tx)?min(N.sub.rx,N.sub.tx), where min( ) is function that returns coefficient with minimum value; performing, by singular-value decomposer, SVD on dimension-reduced channel matrix to determine singular vectors and corresponding coefficients that maximize singular values of singular vectors; outputting result of SVD based on at least one of when dimension of dimension-reduced channel matrix is less than or equal to 2 and when two greatest singular values of corresponding singular vectors are determined; when result of SVD not output, subtracting, by singular-value decomposer, singular vectors from dimension-reduced channel matrix to reduce rank and returning to performing SVD.

Systems and methods are described for coordinating transmissions in distributed wireless systems via user clustering. For example, a method according to one embodiment of the invention comprises: measuring link quality between a target user and a plurality of distributed-input distributed-output (DIDO) distributed antennas of base transceiver stations (BTSs); using the link quality measurements to define a user cluster; measuring channel state information (CSI) between each user and each DIDO antenna within a defined user cluster; and precoding data transmissions between each DIDO antenna and each user within the user cluster based on the measured CSI.

A method of transmission over multiple wireless channels in a multiple antenna system includes storing channel modulation matrices at a transmitter; receiving quantized channel state information at the transmitter from plural receivers; selecting a transmission modulation matrix using the quantized channel state information from the stored channel modulation matrices; and transmitting over the multiple channels to the plural receivers using the selected transmission modulation matrix. In another embodiment, the method includes storing, at one or more receivers, indexes of modulation matrices generated by a capacity enhancing algorithm; upon a selected one of the one or more receivers receiving a transmission from the transmitter, the selected receiver selecting a modulation matrix from the stored modulation matrices that optimizes transmission between the transmitter and the selected receiver, the selected receiver sending an index representing the selected modulation matrix; and receiving the index at the transmitter from the selected receiver.

A method for a transmitting end transmitting a signal to a receiving end in a wireless communication system is provided. The method includes receiving, from the receiving end, information on a first precoder and a second precoder which are for a channel between the transmitting end and the receiving end and transmitting a signal to the receiving end based on the first precoder where the signal is transmitted to the receiving end based on the second precoder if the receiving performance of the receiving end based on the first precoder is greater than or equal to a threshold value.

A method of transmitting a plurality of data streams across a MIMO channel from a transmitter to a receiver, the transmitter comprising an array of antennas, the method comprising acquiring channel state information for a plurality of subcarrier frequencies, determining a mapping that defines, for each frequency, how each data stream is to be mapped to each antenna in the array, and for each antenna in the array, adjusting the power allocated to each data stream that is to be transmitted from the antenna, so as to maximize a measure of throughput; wherein for each data stream, the power allocated to transmitting that data stream at each frequency is greater than or equal to zero, and for each frequency, the power transmitted by any one antenna does not exceed a threshold, and for each data stream, the same power is allocated to each subcarrier used for transmitting that data stream.

Embodiments of the present invention provide a method for determining a transmission rate supported by a data stream, user equipment, and a base station. The method includes: determining, by user equipment UE, a first index corresponding to an average transmission rate supported by a channel between the UE and the base station; determining, by the UE, a second index corresponding to a difference between an instantaneous transmission rate supported by a data stream on the channel and an average transmission rate supported by the data stream on the channel; sending, by the UE, the first index to the base station; and sending, by the UE, the second index to the base station. According to the embodiments of the present invention, the instantaneous transmission rate supported by the data stream on the channel can be relatively accurately fed back to the base station, thereby improving channel resource utilization.

Non-linear or linear precoding is used to create separate areas of coherence to different users. Limited feedback techniques may also be employed to send channel state information (CSI) from the plurality of users to the MU-MAS. In some embodiments, a codebook is built based on basis functions that span the radiated field of a transmit array. Additionally, the precoding may be continuously updated to create non-interfering areas of coherence to the users as the wireless channel changes due to Doppler effect. Moreover, the size of the areas of coherence may be dynamically adjusted depending on the distribution of users.

Systems and methods for performing energy efficient communication. A transceiver for use in a point-to-point packet-based communication link with packet erasures is described. The transceiver can include a data source to provide bits of data for transmission to a remote device. The transceiver can map the bits of data to symbols in a constellation according to a modulation scheme and can provide the symbols on one or more subcarriers. The transceiver can include co-located orthogonally polarized antenna elements or spatially separated antenna elements or both. The symbols can be transmitted in packets via one or more of the antenna elements. The transceiver can determine a metric of average transmit energy per bit successfully decoded, and not erased, at the remote device and can adjust transmission powers at the antenna elements to reduce the average transmit energy per successfully decoded and unerased bit.

Antennas and MIMO antenna arrays in a housing of an electronic device are described. The MIMO antenna array includes a plurality of antennas. At least one of the antennas has operating frequency ranges of 700 MHz-900 MHz, 1700 MHz-2100 MHz, and 3 GHz-5 GHz. The MIMO antenna array may include 8 or 10 antennas.

A channel estimation unit estimates channel state information to or from a base station device. A feedback information generation unit performs a decomposition process for the channel state information and thereby acquires first decomposition information that includes plural singular values and second decomposition information that includes plural right singular vectors respectively associated with the plural singular values. The feedback information generation unit mutually replaces portions of the plural singular values, thereby acquires first replacement information, and further acquires second replacement information based on the first replacement information and the plural right singular vectors. The feedback information generation unit performs a conversion process for the second replacement information and thereby acquires second conversion information. A radio transmission unit notifies the base station device of the second conversion information.