Abstract: The present invention relates to a receiver comprising a fast power control unit, said fast power control unit being arranged to continuously control a quality measure of a radio channel. The receiver is characterized in that the quality measure is a modified Signal to Interference plus noise ratio (SIR) in which the influence from self interference has been removed. The invention further relates to a method for continuously controlling a quality measure of a radio channel, wherein a modified Signal to Interference plus noise ratio (SIR) is continuously determined in which the influence from self interference has been removed.

Abstract: Teachings presented herein offer reduced computational complexity for detecting a plurality of symbol blocks, even for symbol blocks that comprise the combination of a relatively large number of symbols. The teachings perform two or more stages of detection assistance to successively reduce the number of candidate combinations of symbols to be considered for a symbol block when detecting the plurality of symbol blocks. In particular, the teachings identify a reduced set of candidate symbol combinations for at least one symbol block in the plurality of symbol blocks, and then jointly detect each of one or more distinct groups of symbols in the symbol block to determine from that reduced set a final reduced set of candidate symbol combinations. Detection of the plurality of symbol blocks limits the candidate combinations of symbols considered for a symbol block to the final reduced set of candidate symbol combinations identified for that symbol block.

Abstract: A method and apparatus for determining operating modes in a receiver is described herein. A delay searcher in the receiver detects a signal image in the received signal. When the receiver is a RAKE receiver, a plurality of RAKE fingers coherently combine time-shifted versions of the received signal at different delays. Alternatively, when the receiver is a chip equalization receiver, an FIR filter coherently pre-combines the signal images in the received signal. A processor determines delays. In particular, the processor generates a first signal quality metric for a single-delay receiver mode, and generates a second signal quality metric for a multi-delay receiver mode. Based on a comparison of the first and second signal quality metrics, the processor selects the single-delay or the multi-delay receiver mode for processing the signal image.

Abstract: 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.

Abstract: 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).

Abstract: 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.

Abstract: A wireless communication device or system generates transmit power control feedback for a received power control channel by determining a command error rate (CER), or by identifying a target signal quality for the power control channel according to a defined signal-quality-to-CER mapping function. Generally, the power control channel does not include error-coded data to use for CER estimation. However, in one embodiment, the channel does include known reference bits that are evaluated for CER estimation, with the estimated CER used to set the signal quality target for inner loop power control. In other embodiments, a computed reception error probability is used to identify a CER estimate according to a defined probability-to-CER mapping function. By way of non-limiting example, these embodiments may be used to provide power control feedback for power control commands transmitted on a Fractional Dedicated Physical Channel in WCDMA systems.

Abstract: Demodulation and interference parameter estimation in an OFDM receiver is improved by identifying regions, in a two-dimensional array of time-frequency transmission positions, having related interference parameters, such as resulting from the same pre-coding scheme, transmission rank, transmitting antennas, and the like. An interference measure is estimated for each of a plurality of time-frequency positions. The interference measures are analyzed by considering them as pixels, or picture elements, in a two-dimensional image, and applying image processing algorithms to identify the regions having related interference parameters. The image processing algorithms may include operations such as edge detection, segmentation, and/or clustering. The receiver may perform interference suppression or cancellation such as interference rejection combining of data extracted from signals received within an identified time-frequency region having related interference parameters.

Abstract: Teachings presented herein offer a technique for using a demodulator to improve a demodulation process. For example, a demodulation unit according to an embodiment of the present invention may be a multi-stage demodulator and may include: a demodulator configured to receive a baseband signal and configured to produce modem bit likelihood values based on the received baseband signal; a decoder configured to receive and process the modem bit likelihood values to produce improved modem bit likelihood values; a candidate value generator configured to produce, based on the improved modem bit likelihood values, candidate symbol values for a group of one or more symbols; and a detector configured to receive the baseband signal and the candidate symbol values and configured to produce one of (a) final modem bit estimates and (b) candidate symbol values for a group of symbols.

Abstract: Teachings presented herein offer improved symbol block detection by including a decoder unit in a demodulation system. Utilizing a decoder unit in a demodulation system can significantly enhance symbol block detection because the decoder can produce bit likelihood values (soft bit values), and these bit likelihood values can be used to construct a set of candidate symbol values. Advantageously, this set of candidate symbol values is more likely to contain the actually transmitted symbol(s) than if the decoder unit was not used in the demodulation system.

Abstract: 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.

Abstract: Teachings presented herein offer the performance advantages of sequence estimation for received signal symbol detection, while simultaneously providing potentially significant reductions in computational overhead. Initial demodulation of a received signal identifies a reduced number of candidate symbol values for all or a subset of a sequence of symbols represented in a received signal. A sequence estimation process, e.g., an MLSE process, constrains its state spaces to the reduced number of candidate symbols values, rather than considering all possible symbol values.

Abstract: The teachings presented herein improve the processing of individual signals of interest included in a received composite signal by computing combining weights and/or signal quality estimates for each signal of interest, e.g., for linear equalization, based on either shared or non-shared correlation estimates. As a non-limiting advantage, the use of shared correlation estimates reduces computational loading as compared to the processing load that would be needed for computing non-shared correlation estimates for all signals of interest. As a further non-limiting advantage, the conditional use of shared and non-shared correlation estimates provides for the use of non-shared correlation estimates where signal characteristic(s) of one or more of the signals of interest warrant such usage, e.g., for one or more high-rate signals of interest.

Abstract: An iterative demodulator and decoder uses feedback attenuation to maintain proper balance between the demodulator and decoder. Balance is maintained by attenuating the influence of extrinsic information fed back from the decoder to the demodulator to prevent strong decisions by the decoder from overwhelming the demodulator.

Abstract: An SIR estimate of a communication signal in a wireless communication system receiver is calculated based on soft bit values output by a nonlinear detector. The average amplitude of the detector output soft bits is estimated. The average power of the detector output soft bits is estimated, e.g., as a mean-square or variance. An SIR of the communication signal is estimated based on the soft bit amplitude and power estimates. In particular, the SIR is estimated as the ratio of the square of soft bit amplitude to the difference between the mean square soft bit power and the square of soft bit amplitude, or the ratio of the square of soft bit amplitude to the variance. In either case, the SIR estimate may be scaled to obtain the desired units. The communication signal may be a received signal, or a simulated signal generated using channel estimates obtained from, e.g., a pilot channel.

Abstract: A method and apparatus provide advantageous uplink power control for a set of uplink channels transmitted by a mobile terminal or other item of user equipment (UE). The proposed uplink power control maintains the total received power for the set of uplink channels at or about a target received power, while also maintaining the received signal quality for a subset of those channels—e.g., a particular one of them—at or about a target received signal quality. In an advantageous but non-limiting example embodiment, the subset comprises a fixed-rate control channel, and the set includes that control channel and a variable-rate traffic channel. Correspondingly, a base station generates first power control commands to maintain the received signal quality of the control channel at or about some quality target, and generates second power control commands to maintain the total received power (of the two channels) at or about some power target.

Abstract: 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.

Abstract: Teachings presented herein offer a technique for using a demodulator to improve a demodulation process. For example, a demodulation unit according to an embodiment of the present invention may be a multi-stage demodulator and may include: a demodulator configured to receive a baseband signal and configured to produce modem bit likelihood values based on the received baseband signal; a decoder configured to receive and process the modem bit likelihood values to produce improved modem bit likelihood values; a candidate value generator configured to produce, based on the improved modem bit likelihood values, candidate symbol values for a group of one or more symbols; and a detector configured to receive the baseband signal and the candidate symbol values and configured to produce one of (a) final modem bit estimates and (b) candidate symbol values for a group of symbols.

Abstract: A symbol detector converts initial symbol estimates of received symbols to soft estimates for decoding. The symbol detector computes spreading waveform correlations between a spreading waveform for a symbol of interest and spreading waveforms for one or more interfering symbols. Interference rejection terms are computed by scaling the spreading waveform correlations by corresponding signal powers and compensating for noise. A soft scaling factor for the symbol of interest is computed from the interference rejection terms. The soft scaling factors are then applied to the initial symbol estimates to generate the soft estimates.

Abstract: According to the teachings presented herein, a method and apparatus for communication signal processing advantageously use a mix of parametric and non-parametric correlation estimation in communication signal processing. Non-parametric estimation generates an “overall” correlation estimate for a received communication signal, and parametric estimation generates a “component” correlation estimate. The component correlation estimate is removed from the overall correlation estimate to form a partial correlation estimate that is used to process the received communication signal at least initially, such as in a pre-equalization stage. The overall and component correlation estimates are generated as impairment and/or data correlation estimates.