Abstract: Systems and methods for interference cancellation at a receiver in a wireless communication system are provided. In one aspect, a method for interference cancellation is provided. The method comprises providing total received chips received from a plurality of cells. The method also comprises successively estimating received chips for each of the plurality of cells in a plurality of iterations, wherein each of the plurality of iterations after a first iteration comprises canceling previously estimated received chips for one or more of the plurality of cells from the total received chips, and estimating received chips for one of the plurality of cells using the total received chips with the previously estimated received chips for the one or more of the plurality of cells cancelled out.

Abstract: An interference cancellation receiver for a pre-coded orthogonal frequency division multiplexed (OFDM) based system combines temporal interference cancellation within the OFDM framework. Multi-path equalization and inter-symbol interference (ISI) cancellation are performed on a time domain channel estimate of a received signal. An output from the multi-path equalization is transformed to the frequency domain. Inter-channel interference (ICI) is performed in the frequency domain on an equalized signal from the multi-path equalization after transforming the equalized signal from the time domain to the frequency domain.

Abstract: A signal reception method includes receiving a signal over a channel, producing a first equalized signal, a first interference suppression filter and a first estimate of the channel using a portion of a the received signal, dividing the received signal into a plurality of signal blocks, and for each one of the plurality of signal blocks, producing a second equalized signal using a portion of the first equalized signal by selecting from one of a linear estimator or a non-linear estimator and estimating symbols received in the one of the plurality of signal blocks based on the second equalized signal.

Abstract: Systems and methods for symbol detection using sub-constellations are provided. In one aspect of the disclosure, an apparatus is provided. The apparatus comprises a processing unit configured to process received chips into received symbols for a plurality of users, a first detection unit configured to detect first components of user symbols for the plurality of users based on the received symbols and a computation unit configured to compute a portion of the received symbols due to the first components of the user symbols. The apparatus further comprises a second detection unit configured to detect second components of the user symbols based on the received symbols with the computed portion removed and a combining unit configured to detect the user symbols by combining the first components of the user symbols with the respective second components of the user symbols.

Abstract: Systems and methods for multi-user interference cancellation are provided. In one aspect of the disclosure, an apparatus is provided. The apparatus comprises a processing unit configured to process received chips into received symbols for a plurality of users and a detection unit configured to detect user symbols from the received symbols. The apparatus also comprises an interference cancellation unit configured to compute multi-user interference using the detected user symbols and to remove the computed multi-user interference from the received symbols. The apparatus further comprises a redetection unit configured to redetect user symbols from the received symbols with the computed multi-user interference removed.

Abstract: A method includes performing an operation based on transformed channel data and transformed signal data to generate a transform representation of multiple taps. The transformed channel data and the transformed signal data correspond to data received at a receiver. An inverse transform of the transform representation is determined to generate multiple taps for use at an equalizer of the receiver. At least one of the multiple taps is discarded to generate updated filter taps for the equalizer.

Abstract: Certain aspects of the present disclosure propose a method for estimating a channel utilizing Sparse Bayesian Learning (SBL) algorithm. The proposed method employs a Basis expansion (e.g., polynomial) channel model, and iteratively performs SBL algorithm to adjust parameters of the channel model.

Abstract: An apparatus and method for a two-stage linear/nonlinear interference cancellation comprising processing a receive signal to produce a first descrambled signal; and processing the first descrambled signal to produce a detected signal. In one aspect, a first interference canceller module is used for processing the received signal and a second interference canceller module is used for processing the first descrambled signal. In one aspect, the first interference canceller is a linear interference canceller (IC) and the second interference canceller is a linear/nonlinear interference canceller (IC).

Abstract: Channel estimation at a user equipment includes estimating channel quality of at least one channel. A first algorithm or a second algorithm is selected based on the estimated channel quality. Channel estimation is performed based on the selected algorithm. The first algorithm may be a midamble multiplication-based algorithm. The second algorithm may be a midamble division algorithm. Channel estimation may also include estimating noise of a channel and adaptively setting a threshold based on the estimated noise to refine the channel estimation. The estimating channel quality, selecting of a first or second algorithm and channel estimation may be performed iteratively for contributing signals on a channel. An adaptive threshold may be modified across iterations. The channel estimation may also include determining a delay profile of a channel to refine the channel estimation.

Abstract: A system for measuring a rise-over-thermal (RoT) characteristic in a communication network includes controlling a transmitting station to maintain its transmit power at a substantially constant level for a first time interval, and measuring a first received power level. The transmitting station is then controlled to adjust its transmit power by a selectable amount for a second time interval, and a second received power level is measured. The first and second received power levels are then processed to determine the RoT characteristic.

Abstract: Interference cancellation at a user equipment includes performing channel estimation for each component of an aggregate received signal using at least one received midamble of at least one time slot. The aggregate received signal is received from at least one Node B. A combined channel is computed for each channelization code based on the channel estimation. A linear transfer function is obtained for all user equipment within a cell. This linear transfer function includes a combined channel for each channelization code. An equalization matrix is derived from the linear transfer function and then applied to the aggregate received signal to obtain the component intended for the user equipment.

Abstract: A signal reception method includes receiving a signal over a channel, producing a first equalized signal, a first interference suppression filter and a first estimate of the channel using a portion of a the received signal, dividing the received signal into a plurality of signal blocks, and for each one of the plurality of signal blocks, producing a second equalized signal using a portion of the first equalized signal by selecting from one of a linear estimator or a non-linear estimator and estimating symbols received in the one of the plurality of signal blocks based on the second equalized signal.

Abstract: A method for timing and frequency synchronization in a wireless system is provided. The method comprises the steps of receiving a burst of symbols, selecting a subset of the burst of symbols, iteratively adjusting the subset of the burst of symbols by a plurality of timing offsets and calculating, for each timing offset, a first performance metric corresponding to the adjusted subset. The method further comprises the steps of determining one of the plurality of timing offsets to be a preferred timing offset based upon the first performance metric thereof, iteratively rotating the subset of the burst of symbols by a plurality of frequency offsets and calculating, for each frequency offset, a second performance metric corresponding to the rotated subset, and determining one of the plurality of frequency offsets to be a preferred frequency offset based upon the second performance metric thereof.

Abstract: An apparatus and method for compressive sensing tap identification for channel estimation comprising identifying a set of significant taps in the time domain; representing a time-flat channel response using a Taylor series expansion with the set of significant taps; converting the time-flat channel response to a vectorized channel response; transforming the vectorized channel response to a compressive sensing (CS) polynomial frequency response; aggregating the CS polynomial frequency response into a stacked frequency response; converting the stacked frequency response into a measured pilot frequency response; estimating a channel parameter vector based on the measured pilot frequency response; and generating a reconstructed channel response from the channel parameter vector.

Abstract: An apparatus and method for channel estimation comprising obtaining a response matrix G(l) using Q quantity pilots; constructing a sensing matrix Wsensing based on K quantity tones, L quantity symbols and P quantity multipaths; and using compressive sensing channel estimation to determine an equivalent channel matrix Gp(i) based on the response matrix G(l) and the sensing matrix Wsensing.

Abstract: An apparatus and method for channel estimation comprising determining a channel impulse response using a Taylor series expansion with a plurality of Taylor series coefficients; determining a channel frequency response based on the channel impulse response; collecting the channel frequency response over a plurality of symbols to obtain a composite channel frequency response; generating a sensing matrix based on the Taylor series expansion; and determining the plurality of Taylor series coefficients based on the composite channel frequency response and the sensing matrix using compressive sensing channel estimation.

Abstract: Techniques for recovering a desired transmission in the presence of interfering transmissions are described. For iterative detection and cancellation, multiple groups of code channels are formed for a plurality of code channels for at least one sector. Processing is performed for the multiple groups of code channels in multiple iterations. For each iteration, data detection and signal cancellation are performed for the multiple groups of code channels in multiple stages, e.g., in a sequential order starting with the strongest group to the weakest group. Each stage of each iteration may perform data detection, signal reconstruction, and signal cancellation. Each stage of each iteration may also perform equalization, data detection, signal reconstruction, and signal cancellation.

Abstract: A decision feedback equalizer includes a chip estimate buffer that forms chip estimates into a vector. A CCK decoder decodes the vector of chip estimates, and a CCK encoder, connected with the CCK decoder, re-encodes the vector of chip estimates into a valid CCK code word. At the same time, a chip slicer provides direct sliced chips from the chip estimates. An update module then forms a hybrid vector from the valid CCK code-word and the direct sliced chips for input to the feedback filter of the decision feedback equalizer. The hybrid feedback filter input vector reflects the CCK coding gain of its re-encoded portion thereby reducing the estimated chip error rate to improve the performance of the decision feedback equalizer.

Abstract: A method for midamble estimation comprises the steps of receiving a burst of symbols, selecting a subset of the burst of symbols that comprises a first midamble symbol, calculating, for each symbol in the subset, a corresponding midamble estimation error, and determining the lowest calculated midamble estimation error to locate the first midamble symbol. A receiver comprises an antenna configured to receive a burst of symbols, a timing estimator configured to select a subset of the burst of symbols that comprises a first midamble symbol, a midamble estimator configured to calculate, for each symbol in the subset, a corresponding midamble estimation error, and a processor configured to select the symbol in the subset corresponding to a lowest calculated midamble estimation error as the first midamble symbol.

Abstract: Techniques for performing adaptive channel estimation are described. A receiver derives channel estimates for a wireless channel based on received pilot symbols and at least one estimation parameter. The receiver updates the at least one estimation parameter based on the received pilot symbols. The at least one estimation parameter may be for an innovations representation model of the wireless channel and may be updated based on a cost function with costs defined by prediction errors. In one design, the receiver derives predicted pilot symbols based on the received pilot symbols and the at least one estimation parameter, determines prediction errors based on the received pilot symbols and the predicted pilot symbols, and further derives error gradients based on the prediction errors. The receiver then updates the at least one estimation parameter based on the error gradients and the prediction errors, e.g., if a stability test is satisfied.