Abstract: Systems and methodologies are described that facilitate equalization of received signals in a wireless communication environment. Using multiple transmit and/or receive antennas and MIMO technology, multiple data streams can be transmitted within a single tone. During equalization, receivers can separate data received within a tone into individual data streams. The equalization process generally is computationally expensive. Equalizer functions include the inverse operation, which can be computed using the fast square root method; however, the fast square root method involves large numbers of computations for a set of matrices, where the size of a matrix in the set of matrices increases with the number of transmit or receive antennas. Utilizing a modification of the fast square root method, a subset of the elements of the matrices can be selected and updated to reduce the number and/or complexity of computations.

Abstract: A method of controlling gains within a repeater may include determining a power control set point value which controls a transmit power of a mobile station (MS), and receiving a downlink signal from a base station transceiver system (BTS). The method may further include measuring a power of the received downlink signal, and computing a power level of a signal expected at the uplink of the repeater, wherein the computing is based on the measured downlink power and the power control set point value. Finally, the method may further include adjusting a gain of at least one amplifier based on the computed power level. An apparatus for controlling gains in a repeater may include a baseband processor for performing the above method.

Abstract: A method for adjusting per-carrier gains in a repeater is presented. The method may include determining a separate gain value for each carrier frequency in a signal. The method may further include applying the separate gain value to each carrier frequency in the signal to form a per-carrier gain adjusted signal. The method may also include adjusting the separate gain values based upon a per-carrier stability metric.

Abstract: A method of controlling gains in an interference cancellation repeater includes receiving a combined signal which comprises a downlink signal transmitted from a base station transceiver system (BTS) and a feedback signal. The method further includes performing interference cancellation on the combined signal to substantially remove the feedback signal from the downlink signal. The method further includes determining a path loss between the BTS and the interference cancellation repeater based on the downlink signal after interference cancellation is performed, and adjusting at least one gain in the interference cancellation repeater based on the path loss. An interference cancellation repeater which controls gains based on a downlink path loss includes a first and second transceiver coupled to a first and second antenna, respectively, and a baseband processor configure to perform the above method.

Abstract: A wireless repeater has a receiving antenna for receiving an input signal and a transmitting antenna for transmitting an amplified signal where the input signal is a sum of a remote signal and a feedback signal. The repeater includes an echo canceller receiving the input signal and generating an echo cancelled signal by estimating a feedback channel between the transmitting antenna and the receiving antenna and cancelling a feedback signal estimate from the input signal, an amplifier for amplifying the echo cancelled signal and providing the amplified signal to the transmitting antenna, and a variable delay element receiving the echo cancelled signal and introducing a first delay to the echo cancelled signal. The first delay is selected to optimize the estimation of the feedback channel, thereby optimizing the cancellation of the feedback signal. The delayed echo cancelled signal is coupled to the echo canceller as a reference signal for estimating the feedback channel.

Abstract: A method for detecting and reducing aliasing is described. The method may be implemented by a first wireless device. A first signal may be transmitted on a first frequency channel. A second signal may be received on a second frequency channel. The second signal may be received concurrently with the transmission of the first signal. Aliasing of the first signal on the second signal may be detected. Aliasing may be reduced.

Abstract: A wireless repeater includes a channel estimation block to estimate a feedback channel between the antennas of the repeater using frequency domain channel estimation. The repeater includes a pilot signal blanking circuit to blank out a selected number of samples of the pilot signal to improve the accuracy of the channel estimation. In another embodiment, the repeater replaces T samples of the pilot signal with a cyclic prefix.

Abstract: A wireless repeater introduces a low level noise to the signal path of the repeater where the introduced noise is used to facilitate channel estimation. The introduced low power level noise may be added to the receive signal or to the transmit signal. The low power noise signal ensures that the repeater always has a reference signal for performing channel estimation, even when the repeater is not receiving any incoming signal traffic. In one embodiment, a low noise signal is inserted to the transmit circuit of the repeater. In another embodiment, the repeater is configured to increase the noise figure of the receive circuit where the detected noise figure acts as a receive signal.

Abstract: Apparatuses and methodologies are described that increase system capacity in a multi-access wireless communication system. Spatial dimensions may be utilized to distinguish between multiple signals utilizing the same channel and thereby increase system capacity. Signals may be separated by applying beamforming weights based upon the spatial signature of the user device-base station pair. Grouping spatially orthogonal or disparate user devices on the same channel facilitates separation of signals and maximization of user device throughput performance. User devices may be reassigned to groups periodically or based upon changes in the spatial relationships between the user devices and the base station.

Abstract: A wireless repeater includes an echo canceller to cancel an estimated feedback amount from an input signal and a delay to delay the input signal. The delay may be selected to decorrelate a remote signal from a signal to be transmitted by the repeater.

Abstract: Techniques to perform channel estimation with pilot weighting are described. A receiver receives at least one transmission symbol for a pilot transmitted by a transmitter. Each transmission symbol may be generated with a single-carrier multiplexing scheme (e.g., IFDMA or LFDMA) or a multi-carrier multiplexing scheme (e.g., OFDMA). The receiver processes each received transmission symbol and obtains received pilot values. The receiver may derive an interference estimate based on the received pilot values and may estimate the reliability of the received pilot values based on the interference estimate. The receiver determines weights for the received pilot values based on the transmitted pilot values, the estimated reliability of the received pilot values, and/or other information. The receiver derives a channel estimate based on the received pilot values and the weights. The receiver then performs data detection (e.g., equalization) on received data values with the channel estimate.

Abstract: A method in a wireless repeater selects one or more carriers out of all carriers for amplification and transmission. The non-selected carriers may be blocked to mitigate delay spread, uplink noise contribution or other effects on the repeater environment due to multiple repeaters. The carriers may be selected based on signal characteristics, signal usage, and/or other parameters.

Abstract: A device for generating a pilot signal for use in a wireless repeater where the pilot signal is added to a transmit signal for transmission includes a pilot power control unit configured to set a power level of the pilot signal as a function of a gain of the repeater and a power level of the transmit signal, where the function comprises a linear or non-linear function. In one embodiment, the operation of the repeater may be divided into gain regions and the inserted pilot power is controlled according to the different gain regions of the repeater. When the repeater gain is low, the pilot power may be set greater than the transmit power to ensure there is sufficient signal to use for channel estimation. When the repeater gain is in steady state, the pilot power may be set to be lower than the transmit power to avoid interference.

Abstract: Provided is a more efficient manner of transmitting a control message to reach into a neighboring sector (e.g., inter-sector) of a wireless network environment. The control message can be utilized for purposes such as handoff, indicating an amount of interference, inter-sector power control for managing inter-sector interference, sector loading, or other control messages. The control message can be placed on a set of resources utilizing planned reuse and/or statistical reuse. Statistical reuse includes selecting a subcarrier set for carrying the control message. According to some aspects, the control message can be sent over a backhaul channel.

Abstract: In an embodiment, a first repeater configures a beacon signal that identifies the first repeater to one or more other repeaters. The first repeater transmits the configured beacon signal at a given transmission power level to the one or more other repeaters. The transmitted beacon signal is received at least by a second repeater. The second repeater reduces interference associated with other transmissions from the first repeater, such as retransmissions of donor signals, based on the received beacon signal.

Abstract: A wireless repeater having a receiving antenna for receiving an input signal and a transmitting antenna for transmitting an amplified signal includes first and second front-end circuits and a repeater baseband block coupled between the first and second front-end circuits. The repeater baseband block includes a channel estimation block, an echo canceller implementing time domain echo cancellation, a variable gain stage controlled by a gain control block implementing digital gain control, a first variable delay element introducing a first delay before or after the echo canceller, a second variable delay element introducing a second delay to the output signal. The delayed output signal is coupled to the channel estimation block as a reference signal for estimating the feedback channel, to the echo canceller as a reference signal for estimating the feedback signal, and to the gain control block for monitoring the stability of the repeater.

Abstract: A method for controlling gain in a wireless repeater includes providing one or more gain control metrics where the gain control metrics is indicative of a loop gain of the repeater; measuring the one or more gain control metrics; and adjusting a variable gain of the repeater using a gain adjustment step size being a function of at least the loop gain of the repeater as measured by the one or more gain control metrics. In another embodiment, the gain control algorithm block is configured to divide the loop gain of the repeater into multiple gain adjustment control zones. The gain adjustment control zones may include a first zone having a loop gain in a stable operating region and a second zone having a loop gain outside the stable operating region.

Abstract: Transmission schemes that can flexibly achieve the desired spatial multiplexing order, spatial diversity order, and channel estimation overhead order are described. For data transmission, the assigned subcarriers and spatial multiplexing order (M) for a receiver are determined, where M?1. For each assigned subcarrier, M virtual antennas are selected from among V virtual antennas formed with V columns of an orthonormal matrix, where V?M. V may be selected to achieve the desired spatial diversity order and channel estimation overhead order. Output symbols are mapped to the M virtual antennas selected for each assigned subcarrier by applying the orthonormal matrix. Pilot symbols are also mapped to the V virtual antennas. The mapped symbols are provided for transmission from T transmit antennas, where T?V. Transmission symbols are generated for the mapped symbols, e.g., based on OFDM or SC-FDMA. Different cyclic delays may be applied for the T transmit antennas to improve diversity.

Abstract: Transmission schemes that can flexibly achieve the desired spatial multiplexing order, spatial diversity order, and channel estimation overhead order are described. For data transmission, the assigned subcarriers and spatial multiplexing order (M) for a receiver are determined, where M?1. For each assigned subcarrier, M virtual antennas are selected from among V virtual antennas formed with V columns of an orthonormal matrix, where V?M. V may be selected to achieve the desired spatial diversity order and channel estimation overhead order. Output symbols are mapped to the M virtual antennas selected for each assigned subcarrier by applying the orthonormal matrix. Pilot symbols are also mapped to the V virtual antennas. The mapped symbols are provided for transmission from T transmit antennas, where T?V. Transmission symbols are generated for the mapped symbols, e.g., based on OFDM or SC-FDMA. Different cyclic delays may be applied for the T transmit antennas to improve diversity.

Abstract: Transmission schemes that can flexibly achieve the desired spatial multiplexing order, spatial diversity order, and channel estimation overhead order are described. For data transmission, the assigned subcarriers and spatial multiplexing order (M) for a receiver are determined, where M?1. For each assigned subcarrier, M virtual antennas are selected from among V virtual antennas formed with V columns of an orthonormal matrix, where V?M. V may be selected to achieve the desired spatial diversity order and channel estimation overhead order. Output symbols are mapped to the M virtual antennas selected for each assigned subcarrier by applying the orthonormal matrix. Pilot symbols are also mapped to the V virtual antennas. The mapped symbols are provided for transmission from T transmit antennas, where T?V. Transmission symbols are generated for the mapped symbols, e.g, based on OFDM or SC-FDMA. Different cyclic delays may be applied for the T transmit antennas to improve diversity.