摘要:
A two stage interference cancellation (IC) process includes a linear IC stage that suppresses co-channel interference (CCI) and adjacent channel interference (ACI). The linear IC stage disambiguates otherwise super-trellis data for non-linear cancellation. Soft linear IC processing is driven by a-posteriori probability (Apop) information. A second stage performs expectation maximization/Baum Welch (EM-BW) processing that reduces residual ISI left over from the first stage and also generates the Apop which drives the soft linear IC in an iterative manner.
摘要:
A two stage interference cancellation (IC) process includes a linear IC stage that suppresses co-channel interference (CCI) and adjacent channel interference (ACI). The linear IC stage disambiguates otherwise super-trellis data for non-linear cancellation. Soft linear IC processing is driven by a-posteriori probability (Apop) information. A second stage performs expectation maximization/Baum Welch (EM-BW) processing that reduces residual ISI left over from the first stage and also generates the Apop which drives the soft linear IC in an iterative manner.
摘要:
A novel symbol estimation method produces intersymbol interference free symbols by detecting interfering symbols in an interfering channel. A channel estimate is refined for additional improvements. The method can lends itself as a serial or parallel algorithm implementation. The symbol estimation method includes using an initial estimate of received symbols and calculating a refined estimate of the received symbols using a channel estimate. The refined estimate is calculated by performing parameterization of intersymbol interference by symbols other than the symbol being refined and selecting a refined value for the symbol being refined by evaluating an optimization function. Symbol estimates are refined in multiple iterations, until a predetermined iteration termination criterion is met. Parameterization of ISI contribution of other symbols results in reduced computation by reducing total number of unknown variables in the refinement operation.
摘要:
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.
摘要:
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.
摘要:
A multi-stage interference suppression receiver includes a short equalizer section configured to operate on a first portion of a received signal received over a channel to produce a first equalized signal and a first estimate of the channel, a channel estimator section configured to operate on the first equalized signal to produce a second equalized signal, the channel estimator section comprising a linear estimator and a non-linear estimator, a long equalizer section configured to operate on a second portion of the received signal to produce a first estimate of symbols in the received signal and a second estimate of the channel and an interference canceller section configured to operate on the first estimate of symbols in the received signal to generate a second estimate of symbols in the received signal based on, at least in part, the second estimate of the channel.
摘要:
A method for estimating timing in a wireless communication comprises the steps of receiving a plurality of symbol bursts corresponding to a plurality of time slots and selecting a subset of symbols from a first symbol burst of the plurality of symbol bursts. The subset comprises a first midamble symbol. The method further comprises the steps of calculating, for each symbol in the subset, a corresponding midamble estimation error, and determining the lowest calculated midamble estimation error to determine a timing for the first symbol burst. The method further comprises the steps of processing the first symbol burst utilizing the timing determined for the first symbol burst, and processing a second symbol burst of the plurality of symbol bursts utilizing the timing determined for the first symbol burst.
摘要:
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.
摘要:
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.
摘要:
A novel symbol estimation method produces intersymbol interference free symbols by detecting interfering symbols in an interfering channel. A channel estimate is refined for additional improvements. The method can lends itself as a serial or parallel algorithm implementation. The symbol estimation method includes using an initial estimate of received symbols and calculating a refined estimate of the received symbols using a channel estimate. The refined estimate is calculated by performing parameterization of intersymbol interference by symbols other than the symbol being refined and selecting a refined value for the symbol being refined by evaluating an optimization function. Symbol estimates are refined in multiple iterations, until a predetermined iteration termination criterion is met. Parameterization of ISI contribution of other symbols results in reduced computation by reducing total number of unknown variables in the refinement operation.