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:
Estimating an unknown frequency error of a tone signal may comprise sampling, within an error bandwidth, wireless signals including the tone signal that occupy the error bandwidth to generate signal samples, and repeatedly, for different frequency offsets: applying a frequency offset to the signal samples to produce offset values that represent the signals occupying an offset bandwidth equal to the error bandwidth offset by an offset frequency; estimating, within a frequency estimation range less than the error bandwidth, a tone frequency error using the offset values; and measuring a signal-to-noise ratio of the tone signal using the signal samples and the estimated tone frequency error. Other aspects, embodiments, and features are also claimed and discussed.
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:
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:
An apparatus is provided for demodulating a block, the block including a plurality of bursts. The apparatus comprises a demodulator configured to demodulate the plurality of bursts and a modulation detector configured to detect a modulation scheme for a current burst in the plurality of bursts and to determine whether there is a high probability that the detected modulation scheme is correct. The modulation detector instructs the demodulator to demodulate each burst subsequent to the current burst in the plurality of bursts based on the detected modulation scheme when the modulation detector determines a high probability that the modulation scheme is correct.
摘要:
Communications devices are adapted to receive a plurality of RF bursts of a radio block, where the plurality of RF bursts includes a number of RF bursts less than a total number of RF bursts for the radio block. A header can be decoded from the received plurality of RF burst. From the decoded header, a determination may be made whether the radio block is intended for the communications device or for another device. According to at least some examples, if the radio block is determined to be intended for another device, at least a portion of a receiver circuit of the communications device can be powered down. Also, according to at least some examples, if the radio block is determined to be intended for the receiving communications device, a data payload of the radio block may be decoded. Other aspects, embodiments, and features are also claimed and described.
摘要:
Decoders and communications devices including such decoders can obtain a convolutional coded bit stream including a plurality of coded data bits. The convolutional coded bit stream may be coded according to one or more generator polynomials such that each information bit is related to two or more coded data bits in a manner to be determinable from a mathematical combination of the two or more coded data bits of the convolutional coded bit stream. A priori information associated with each information bit can be calculated based at least in part on the mathematical combination of the two or more coded data bits. Employing the a priori information, a binary value for each information bit can be calculated. Other aspects, embodiments, and features are also claimed and described.
摘要:
Decoder and communications devices including such decoders can obtain a convolutional coded bit stream including a plurality of coded data bits. According to some implementations, if a signal quality associated with the convolutional coded bit stream is above a predetermined threshold, a decoded value for each information bit may be calculated at least from a modulo 2 sum of a coded data bit added to at least one other coded data bit, at least one previously calculated information bit, or a combination of at least one other coded data bit and at least one previously calculated information bit. Also, according to some implementations, if the signal quality associated with the convolutional coded bit stream is not above the predetermined threshold, the convolutional coded bit stream may be decoded with a conventional convolutional decoding scheme. Other aspects, embodiments, and features are also claimed and described.
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:
Communications devices are adapted to receive a plurality of RF bursts of a radio block, where the plurality of RF bursts includes a number of RF bursts less than a total number of RF bursts for the radio block. A header can be decoded from the received plurality of RF burst. From the decoded header, a determination may be made whether the radio block is intended for the communications device or for another device. According to at least some examples, if the radio block is determined to be intended for another device, at least a portion of a receiver circuit of the communications device can be powered down. Also, according to at least some examples, if the radio block is determined to be intended for the receiving communications device, a data payload of the radio block may be decoded. Other aspects, embodiments, and features are also claimed and described.