Telefonaktiebolaget Lm Ericsson (publ)

Peter Malm

Bengt Lindoff

Andres Reial

Leif Wilhelmsson

Johan Nilsson

Andreas Cedergren

Bo Magnus Bernhardsson

Raymond L Toy

Wensheng Huang

A method for use in receiving a spread-spectrum signal includes receiving an input signal. The input signal includes a first plurality of multipath components. The method also includes despreading the first plurality of multipath components. The step of despreading includes computing a plurality of corresponding delays. The method also includes computing a plurality of combining weights based, at least in part, on interference correlation between at least two of the first plurality of multipath components, selecting, according to at least one criterion, a subset of the plurality of combining weights, and despreading and combining a second plurality of multipath components using at least one quantity related to the selected plurality of combining weights and a plurality of delays and multipath components corresponding to the plurality of selected combining weights. This Abstract is provided to comply with rules requiring an Abstract that allows a searcher or other reader to quickly ascertain subject matter of the technical disclosure. This Abstract is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

Method of and apparatus for multi-path signal component combining

Hypothesis tests, such as maximum likelihood detections, are executed on symbol sequences received by, for example, a user equipment (UE) in a communication system. The hypothesis tester checks a received sequence against a group of predetermined sequences that possibly could have been sent to the UE. For received sequences that are matched or not matched by the hypothesis tester with high confidence, complete decoding, for example, with a Viterbi decoder, is not necessary. Instead, complete decoding is used as a 'tie-breaker' for those sequences which the hypothesis tester cannot match or not match with desired confidence levels.

Efficient detection of predetermined sequences

Method of, and arrangement and device for, decoding a communications signal in a digital communications system, where the communications signal is modulated according to a modulation scheme including amplitude information; generating a likelihood value for a received communications signal, decoding the communications signal based on at least the generated likelihood value, providing a reliability indication of the amplitude information conveyed by the received communications signal wherein the step of generating the likelihood value further comprises generating the likelihood value on the basis of the provided reliability indication of the amplitude information.

Calculation of soft decision values using reliability information of the amplitude

A sub-optimal method is disclosed for calculating the reliability values (soft values) for the bits of a multilevel signal. The log-likelihood values are approximated using only the dominant terms, so called max-log approximation, that is for each bit position only the two closest signal symbols of opposite bit value (S, S) are considered in the sum. The used modulation scheme is 16-QAM together with Gray-labelling. Two versions of approximation are proposed: one version consists of using the two distances between the received value and the two closest symbols of opposite bit value (&#x3b4;&#x3b4;). In order to simplify and speed up the calculation, the second version consists of using the distance between the two closest symbols (&#x3b4;) to approximate the distance between the second closest symbol and the received value. Furthermore, precalculated results are stored in look-up tables to speed up the calculation.

Soft value calculation for multilevel signals

Simple and robust methods and apparatus for switching between different types of combining in a receiver in a communication system are disclosed that minimize Layerprocessing overhead and power consumption. A method of selecting among a plurality of types of combining for received replicas of an information bitstream in a communication system includes the steps of determining a time offset between received replicas; determining a selection threshold; comparing the time offset with the selection threshold; and selecting one of the plurality of combining types based on the comparing step. The system may be a wideband code division multiple access system and the replicas may be included in a multimedia broadcast/multicast service.

Methods and apparatus for selectively processing information replicas

In a packet-based data transmission including incremental redundancy (IR) protocols, the memory consumption of the IR protocol is reduced by compressing and storing failed data units in their punctured format. The failed data units are compressed using low complexity compression/decompression algorithms. The compression algorithm includes two parts: calculating and storing a scale factor for each transmission burst that estimates the soft values in the burst, and storing each soft values' sign in local memory instead of the complete soft value. If the currently received data unit is a retransmission, its compressed versions in the punctured format stored in the IR memory are decompressed, de-punctured and combined with the currently received data unit. The combined data unit is then decoded. The decompression restores an estimated soft-value by multiplying the sign value stored in the IR memory with its corresponding scale factor obtained from a mapping table.

Data compression with incremental redundancy

A method for scheduling a decoding process of coded data blocks transmitted over a link in a communication network. According to the method the coded data block is stored in a queue () if all decoders of a cluster () of iterative parallel decoders are unavailable. When any of the decoders of the cluster () is available the first coded block of the queue () is moved to that decoder. Also, according to the method it is possible to combine a stored coded block with a retransmitted coded block, which is decoded with an increased probability for successful decoding. Also, the invention relates to a communication apparatus adapted for carrying out the method according to the invention.

Method for iterative decoder scheduling

A method and system are described for performing fast and simple M-QAM detection on received signals, such as a 16-QAM signal, by estimating M-QAM symbol constellation decision boundaries. Amplitude information is collected for in-phase and quadrature phase components of the received signal over a number of symbols. An average of the absolute value of the amplitude information of the in-phase components and of the quadrature phase components is determined over the number of symbols. The determined average absolute values of the in-phase and quadrature phase components provide a reference to produce the decision boundary estimates. Bias compensation may optionally be applied to the decision boundary estimates based on the estimated signal-to-interference ratio ('SIR') of the received signal to produce bias corrected decision boundary estimates.

Method and system for M-QAM detection in communication systems

A system and method for DC offset compensation wherein a received first signal is despread using a first spreading code to generate a second signal. The second signal along with a first set of pilot symbols is used to estimate a radio channel. The first signal is also despread using a second spreading code to generate a third signal. A DC offset is estimated from the third signal, the estimated radio channel and a second set of pilot symbols. The estimated DC offset may then be subtracted from the second signal.

System and method for DC offset compensation in a WCDMA receiver

In a packet based data transmission including automatic repeat request (ARQ) protocols, the memory consumption of the ARQ protocol is reduced by compression/decompression of failed data block prior to combination with the retransmitted data blocks using low complexity compression/decompression algorithms. The compression algorithm includes of two parts: calculating and storing a scale factor that estimates the soft values in the data block, and storing the each soft values' sign in local memory instead of the complete soft value. Since one bit is sufficient to store the sign of each soft value, the memory consumption of a data block containing N soft values is N bits. Note, the scale factor increases the memory consumption, in bits, with the word length of the scale factor. However, the relative memory increase becomes smaller the larger the data block.

Compression based on channel characteristics

In accordance with exemplary embodiments of the invention, throughput and capacity in a TDMA system are increased using several different channels all operating simultaneously on the same carrier frequency. In a first embodiment, a base station in a cell in the system simultaneously transmits a different information sequence from each antenna of a transmitter, on the same carrier frequency. Mobile stations in the cell each receive the signals from the base station antennas as a composite signal, and then use known synchronization information to extract a desired information sequence from the composite signal. In a second embodiment, the different information sequences are all intended for the same mobile station, which uses the synchronization information to extract each sequence from the composite signal. In a third embodiment of the invention, the base station simultaneously transmits identical information sequences to a mobile station via different antennas. The mobile station uses the resulting space diversity effect to obtain diversity gain that enables an increase in the number of channels per area-unit, and thus an increase in traffic and spectrum efficiency. The system can also dynamically employ these to effectively respond to changing demands for communications services within the system.

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Lund, Sweden

Peter Malm