摘要:
The quality of a received signal in a non-linear receiver is estimated using a coupling matrix G or Q that describes the interaction of symbols in the received signal with other symbols and/or how the impairment (noise and interference) interacts in the received signal. The coupling matrix is also useful for joint detection. The signal quality estimate may include, e.g., the minimum eigenvalue, and other functions, such as the determinant and trace of the coupling matrix. When G or Q varies with each block, as in CDMA systems employing longcode scrambling, a representative matrix can be used, such as a matrix of RMS values or average magnitudes of real and imaginary components. The signal quality estimate can be expressed as a bit error rate (BER).
摘要:
A receiver comprises plural receive antennas and electronic circuitry. The plural receive antennas are configured to receive, on plural subcarriers transmitted over a radio interface, a frequency domain signal that comprises contribution from a block of time domain symbols. The electronic circuitry is configured or operable to perform symbol detection of time domain symbols comprising the block by performing a multi-stage joint detection procedure comprising plural stages, and thus serves as a detector (40). For a first stage the block is divided into a first number of sub-blocks each having a sub-block first size. For a second stage the block is divided into a second number of sub-blocks each having a sub-block second size, the sub-block second size being greater than the sub-block first size. For each stage a detector (40) formulates frequency domain combining weights and uses the frequency domain combining weights for combining multiple receive versions of each subcarrier to provide candidate symbol combination values for symbols in each sub-block of the respective stage. For the second stage the detector (40) is further configured to use the candidate symbol combination values of the first stage to formulate joint hypotheses to serve as candidates for the joint detection operation of the second stage.
摘要:
A pilot channel signal for time-division multiplexing with one or more traffic channel signals in a broadcast/multi-cast signal and for code-division multiplexing with a continuously transmitted pilot channel signal is described. In an exemplary method for transmitting a broadcast/multicast signal, a pilot symbol sequence is obtained for each slot of one or more frames of the broadcast/multicast signal, so that the pilot symbol sequence varies for each slot of a given frame. The pilot symbol sequence for each slot is spread with a channelization code, and the spread pilot symbol sequence for each slot is scrambled, using a scrambling code, to form a first pilot channel signal. The first pilot channel signal is transmitted so that it is time-division multiplexed with one or more traffic channel signals transmitted during each slot and code-division multiplexed with a second pilot channel signal transmitted during all slots of the one or more frames.
摘要:
Methods and apparatus for determining an impairment covariance matrix for use in an interference-suppressing CDMA receiver are disclosed. In several of the disclosed embodiments, precise information regarding signal propagation delays is not needed. An exemplary method includes the selection of a plurality of processing delays for processing a received CDMA signal. Net channel coefficients for the processing delays are estimated and used to calculate an impairment covariance matrix. The impairment covariance matrix is calculated as a function of the estimated net channel coefficients and the processing delays, without estimating a propagation medium channel response for the received signal.
摘要:
In one of its aspects, the technology concerns a method of processing a signal which includes physical data channels which have been channelized using spreading codes. The method comprises (1) despreading unoccupied spreading codes (e.g., codes which are essentially unobscured by traffic data) included in the signal to obtain unoccupied code despread values, (2) using the unoccupied code despread values to form an impairment covariance matrix; and (3) using the impairment covariance matrix along with a channel estimate to form a processing parameter. The processing parameter can be one of combining sets and a signal quality estimate. In another of its aspects, the technology concerns a coherent, linear equalizer apparatus configured to process a signal which includes physical data channels which have been channelized using spreading codes. The equalizer apparatus comprises plural delay fingers (32) configured to despread unoccupied spreading codes included in the signal to obtain unoccupied code despread values, and a generator (60) configured to use the unoccupied code despread values to form an impairment covariance matrix.
摘要:
A device that estimates information from a signal includes a receiver for receiving an input signal and electronic processing circuitry. The electronic processing circuitry generates a matrix associated with the input signal and determines an approximation of an inverse of the matrix based on the adjoint of the matrix and a scaling factor associated with the determinant of the matrix. This approximation avoids possible mathematical difficulties that may be encountered in certain situations when a typical matrix inversion is calculated. The approximated inverse matrix is applied to the input signal to transform the input signal into an output signal. Information associated with the input signal is then determined based on the output signal.
摘要:
A node (e.g., base station, signal processing unit) is described herein that includes a symbol detector and a method which are capable of suppressing interference caused by one user device (which may be in softer handoff mode) to reduce performance degradation to other intra-cell user devices and/or other inter-cell user devices (which may not be in softer handoff mode).
摘要:
The computation of code-specific channel matrices for an Assisted Maximum Likelihood Detection (AMLD) receiver comprises separately computing high rate matrices that change each symbol period, and a low rate matrix that is substantially constant over a plurality of symbol periods. The high and low rate matrices are combined to generate a code-specific channel matrix for each receiver stage. The high rate matrices include scrambling and spreading code information, and the low rate matrices include information on the net channel response and combining weights. The low rate matrices are efficiently computed by a linear convolution in the frequency domain of the net channel response and combining weights (with zero padding to avoid circular convolution), then transforming the convolution to the time domain and extracting matrix elements. Where the combining weights are constant across stages, a common code-specific channel matrix may be computed and used in multiple AMLD receiver stages.
摘要:
Teachings presented herein offer reduced and stable computational complexity for symbol block detection using multi-stage assistance, and also provide for the generation of soft bit values. A demodulator generates these soft bit values by forming from a set of candidate symbol combinations, for each group of symbols in a symbol block, a subset of candidate symbol combinations for that group. The demodulator selects from the set the most likely combination, at least one combination that has a complementary bit value for a respective bit value in the most likely combination, and as many of the next most likely combinations not already selected as are needed for the size of the subset to conform to a pre-determined size. The demodulator generates soft bit values by limiting the candidate combinations of symbols considered for a symbol block according to the subsets formed for the groups of symbols in that symbol block.
摘要:
Method and apparatuses taught herein enable link adaptation feedback to be determined in advance for future transmit intervals, based on one or more data sending units sending indications of future transmit resource allocations, and receiving corresponding link adaptation feedback from data receiving units. Knowledge of the future transmit resource allocations enable individual data sending units to predict interference conditions for the future transmit interval, and thereby compute link adaptation feedback that takes advantage of low-interference conditions. Individual data sending units receive link adaptation feedback for the future transmit interval from the data receiving units they are supporting, and make corresponding link adaptations for the future transmit interval. Such operations are, in one or more embodiments, carried out in a Wideband Code Division Multiple Access (WCDMA), Long Term Evolution LTE), or WiMAX network, wherein the data sending units comprise radio base stations, and the data receiving units comprise wireless communication devices.