Abstract: Aspects of a greedy search user group selection scheme with range reduction for FDD multiuser MIMO downlink transmission with finite-rate channel state information feedback are provided. The method may comprise receiving feedback information via a communication channel for a plurality of users in a frequency division duplex system. The system capacity may be maximized using the feedback information based on a signal from a single user within a reduced search range or based on the signal from the single user and at least one other signal from another user within a remaining portion of the search range. The feedback information may comprise quantized gain and/or direction of the channel state information of the users.

Abstract: A method and system for a double search algorithm of user group selection for multiuser MIMO downlink transmission are provided. The use of optimal brute-force user group selection may require high computational expense. A first search operation may be based on a first user having a channel gain greater than that of other users, while a second search operation may be based on a second user having a channel gain greater than that of the remaining users. A maximized system capacity may be determined based on the maximized system capacities determined in the first and second search loop. A receiver pair associated with the maximized system capacity may be selected as the user group. The double search algorithm may reduce the computational complexity while achieving performances that may exceed the TDMA scheme and be similar to that of systems with ideal CSI at the transmitter.

Abstract: In a communication system, user equipment (UE) conditionally performs uplink transmit diversity (ULTD) either by Switched Antenna Transmit Diversity (SATD) or Beamforming Transmit Diversity (BFTD) using a first antenna and a second antenna. Either a serving node or the UE determines that uplink transmit diversity is conditionally authorized. Either a serving node or the UE measures a value. The UE transmits using ULTD in response to determining that an enabling condition based on the value is satisfied. The UE can also disable uplink transmit diversity in response to determining that a disabling condition based on the value is satisfied. The disabling condition comprises a disabling threshold that equals the enabling condition comprising an enabling threshold with a threshold adjustment for hysteresis.

Abstract: Aspects of a double search user group selection scheme with range reduction for FDD multiuser MIMO downlink transmission with finite-rate channel state information feedback are provided. The method may comprise maximizing system capacity using feedback information for a plurality of signals in a frequency division duplex system to reduce a search range within which a group of signals having maximum channel gain are located. The feedback information may comprise quantized gain for the signals. Quantized channel direction for the signals within the reduced search range may be requested and received by the transmitter. One or two signals from the reduced search range that maximizes system capacity may be selected. The receivers associated with these signals may then be selected as the user group.

Abstract: A method and apparatus for providing maximum ratio transmission mobile transmit diversity is provided. The method may include selecting a first transmit power for a first antenna and a second transmit power for a second antenna, wherein the first and second transmit powers are selected to generate a target power output, and using a first average power tracking unit to generate the first selected transmit power and a second average power tracking unit to generate the second selected transmit power.

Abstract: Certain aspects of a method and system for processing signals in a communication system may include maximizing system capacity for a time division duplex (TDD) multiple-input multiple-output (MIMO) system, based on reducing a search range within which to find a group of signals having maximum channel gain. At least one of: a first signal for a first user and a second signal for a second user may be selected, which are both within the reduced search range, and which provides a maximum system capacity. The first signal for the first user may be selected from the reduced search range corresponding to a channel gain that is greater than a channel gain corresponding to a remaining portion of the reduced search range. The reduced search range may be generated by sorting a plurality of signals based on a channel gain corresponding to each of the plurality of signals.

Abstract: Certain aspects of a method and system for processing signals in a communication system may include maximizing system capacity for a time division duplex (TDD) multiuser multiple-input multiple-output (MIMO) downlink system, based on a single signal for a single user within a reduced search range or the single signal for the single user and at least one other signal for one other user within a remaining portion of the reduced search range. The reduced search range may be generated by sorting a plurality of signals based on a channel gain corresponding to each of the plurality of signals. The single signal for the single user may be selected from the reduced search range corresponding to a channel gain that is greater than a channel gain corresponding to a remaining portion of the reduced search range.

Abstract: A method and system for channel quantization for multiuser diversity are provided. A quantizer may utilize quantization levels determined based on an objective function J that corresponds to a performance metric for a finite-rate feedback multiuser downlink communication system. The quantization levels may be obtained based on the results of maximizing the objective function J by means of an optimization algorithm. The optimization algorithm may be a multivariate optimization algorithm that may be implemented utilizing an iterative approach. The quantizer may utilize the quantization levels to quantize channel state information (CSI) to achieve multiuser diversity in the finite-rate feedback multiuser system. The performance metric may be based on signal-to-noise ratio (SNR), bit error rate (BER), and/or system capacity. The quantization levels may be utilized in a multiuser system where distributed quantization is needed for optimal selection.

Abstract: A method for channel selection in a communication system includes receiving a broadcast signal comprising a beam vector, generating a first channel state information message based on the power of the broadcast signal, generating a second channel state information message based on the direction of the broadcast signal with respect to the beam vector, and transmitting a feedback signal comprising at least the first channel state information message and the second channel state information message. The communication system may include a frequency division duplex (FDD) multiuser communication system or a time division duplex (TDD) multiuser communication system. The first channel state information message may include a channel gain with respect to the broadcast signal. The second channel state information message may include a measure of orthogonality between the broadcast signal and the beam vector.

Abstract: A method and system for a double search algorithm of user group selection for multiuser MIMO downlink transmission are provided. The use of optimal brute-force user group selection may require high computational expense. A first search operation may be based on a first user having a channel gain greater than that of other users, while a second search operation may be based on a second user having a channel gain greater than that of the remaining users. A maximized system capacity may be determined based on the maximized system capacities determined in the first and second search loop. A receiver pair associated with the maximized system capacity may be selected as the user group. The double search algorithm may reduce the computational complexity while achieving performances that may exceed the TDMA scheme and be similar to that of systems with ideal CSI at the transmitter.

Abstract: Methods and apparatus are provided for allowing a transmitter (Tx) to perform antenna selection independently of a receiver (Rx) in a transceiver supporting both transmit diversity and receive diversity. Certain aspects may utilize a cross switch, which may be used in a parallel or cross configuration, to provide for the independent antenna selection, such that the Rx may maintain the ability to operate on the same antenna as the Tx, on another antenna, or on both antennas for enhanced receive diversity. Furthermore, certain aspects may employ additional switching in the baseband domain in an effort to avoid, or at least reduce, switching glitches in the Rx caused by changing the cross switch configuration. In this manner, the Rx need not re-converge upon antenna switching.

Abstract: A method for processing signals in a communication system includes selecting, from a plurality of users, a first user having a channel gain that is greater than a channel gain corresponding to a remaining portion of the plurality of users. At least a second user may be selected from a portion of the remaining portion of the plurality of users, based on a feedback channel gain of the second user. The selected second user may have a channel direction that is approximately orthogonal to a channel direction of the first user. System capacity may be determined based on the selecting of the first user and the selecting of the second user. The channel gain may be defined by a quantized channel gain. A quantized channel direction of the selected first user may be determined for the selecting of the second user.

Abstract: A method and system for channel quantization for multiuser diversity are provided. A quantizer may utilize quantization levels determined based on an objective function J that corresponds to a performance metric for a finite-rate feedback multiuser downlink communication system. The quantization levels may be obtained based on the results of maximizing the objective function J by means of an optimization algorithm. The optimization algorithm may be a multivariate optimization algorithm that may be implemented utilizing an iterative approach. The quantizer may utilize the quantization levels to quantize channel state information (CSI) to achieve multiuser diversity in the finite-rate feedback multiuser system. The performance metric may be based on signal-to-noise ratio (SNR), bit error rate (BER), and/or system capacity. The quantization levels may be utilized in a multiuser system where distributed quantization is needed for optimal selection.

Abstract: Certain aspects of a method and system for processing signals in a communication system may include maximizing system capacity for a time division duplex (TDD) multiple-input multiple-output (MIMO) system, based on reducing a search range within which to find a group of signals having maximum channel gain. At least one of: a first signal for a first user and a second signal for a second user may be selected, which are both within the reduced search range, and which provides a maximum system capacity. The first signal for the first user may be selected from the reduced search range corresponding to a channel gain that is greater than a channel gain corresponding to a remaining portion of the reduced search range. The reduced search range may be generated by sorting a plurality of signals based on a channel gain corresponding to each of the plurality of signals.

Abstract: Certain aspects of a method and system for processing signals in a communication system may include maximizing system capacity for a time division duplex (TDD) multiuser multiple-input multiple-output (MIMO) downlink system, based on a single signal for a single user within a reduced search range or the single signal for the single user and at least one other signal for one other user within a remaining portion of the reduced search range. The reduced search range may be generated by sorting a plurality of signals based on a channel gain corresponding to each of the plurality of signals. The single signal for the single user may be selected from the reduced search range corresponding to a channel gain that is greater than a channel gain corresponding to a remaining portion of the reduced search range.

Abstract: Various aspects of a method and a system for a range reduction scheme for user selection in a multiuser MIMO downlink transmission are presented. Aspects of a system for range reduction may comprise a range reduction processor that determines a plurality of channel measurements corresponding to a plurality of signals. The range reduction processor may compute a plurality of channel capacities based on the channel measurements corresponding to a subset of the plurality of signals having channel gain that is greater than a remaining portion of the plurality of signals. Aspects of a method may comprise determining a plurality of channel measurements corresponding to a plurality of signals, and computing a plurality of channel capacities based on said channel measurements corresponding to a subset of the plurality of signals having a channel gain that is greater than a remaining portion of the plurality of signals.

Abstract: A method for communication is disclosed and may include performing, using one or more processors and/or circuits, selecting, from a plurality of signal receiving users in a multiuser communication system, a first signal receiving user having a channel gain that is greater than a channel gain of each corresponding signal receiving user of a remaining portion of the plurality of signal receiving users. A second signal receiving user may be selected from the remaining portion of the plurality of signal receiving users, based on a feedback information comprising orthogonality of a channel direction of the second signal receiving user with respect to a channel direction of the first user. The feedback information may include a channel gain of the second signal receiving user. The communication system may include a frequency division duplex (FDD) multiuser communication system.

Abstract: A method and system for a double search algorithm of user group selection for multiuser MIMO downlink transmission are provided. The use of optimal brute-force user group selection may require high computational expense. A first search operation may be based on a first user having a channel gain greater than that of other users, while a second search operation may be based on a second user having a channel gain greater than that of the remaining users. A maximized system capacity may be determined based on the maximized system capacities determined in the first and second search loop. A receiver pair associated with the maximized system capacity may be selected as the user group. The double search algorithm may reduce the computational complexity while achieving performances that may exceed the TDMA scheme and be similar to that of systems with ideal CSI at the transmitter.

Abstract: Techniques for compensating for I-Q mismatch in a communications receiver. In an exemplary embodiment, incoming I and Q samples are adjusted by multiplying with certain compensation coefficients to generate mismatch-compensated I and Q samples. The compensation coefficients may themselves be calculated and iteratively refined from the mismatch-compensated I and Q samples. Further techniques for partitioning the adjustment and estimation functions among computational hardware are disclosed. In an exemplary embodiment, estimation may be restricted to only those segments of the incoming I and Q samples that fulfill certain conditions, e.g., segments of the incoming I and Q samples known to be statistically uncorrelated and/or to have equal average energy.

Abstract: Various aspects of a method and a system for a range reduction scheme for user selection in a multiuser MIMO downlink transmission are presented. Aspects of a system for range reduction may comprise a range reduction processor that determines a plurality of channel measurements corresponding to a plurality of signals. The range reduction processor may compute a plurality of channel capacities based on the channel measurements corresponding to a subset of the plurality of signals having channel gain that is greater than a remaining portion of the plurality of signals. Aspects of a method may comprise determining a plurality of channel measurements corresponding to a plurality of signals, and computing a plurality of channel capacities based on said channel measurements corresponding to a subset of the plurality of signals having a channel gain that is greater than a remaining portion of the plurality of signals.