Telefonaktiebolaget Lm Ericsson (publ)

St-ericsson Sa

Optis Wireless Technology, LLC

Oct Circuit Technologies International Limited

Elias Jonsson

Douglas Allan Cairns

Andres Reial

Andreas Cedergren

Kazuyoshi Uesaka

Gregory Edward Bottomley

Bengt Lindoff

Johan Nilsson

Oskar Drugge

Yoshitaka Murata

Göran Bergman

Yi-Pin Eric Wang

Stephen J Grant

Bo Magnus Bernhardsson

Xiaohui Wang

Tracy Lawrence Fulghum

Jaroslaw Niewczas

Hiroaki Watabe

Stefan Parkvall

Erik Bengt Dahlman

Basuki Endah Priyanto

Torgny Palenius

Yang Hu

Jonas Ohlsson

Ylva Jading

Anders Rosenqvist

Niclas Danielsson

Anders Ericsson

Amit Singh

Mikael Ziren

Vijaykumar Kuppusamy

Girum Alebachew

Roger Persson

Ioannis Xirouchakis

Dimitrios Triantafillidis

Youssef Senhaji

Tatjana Hrnjez

Jonas Linde

Mårten Myrehed

Rama Kumar Mopidevi

Srikanth Gopal

Eric Blanquer

Hisashi Onozawa

Dinil Koshy Mathews

A method is provided of a wireless communication device operating in connection with a cellular communication system providing a serving cell and one or more interfering cells. A signal is received comprising symbols of the serving cell transmitted in a downlink channel and symbols of the one or more interfering cells and a first function of a signal-to-interference ratio of the received signal is calculated. One or more of the interfering cells are selected as dominant interfering cells based on a respective average power of reference symbols of the one or more interfering cells in the received signal, an average power of demodulated symbols of the serving cell in the received signal and a respective average power of demodulated symbols of each of the dominant interfering cells in the received signal are determined. A metric value is calculated based on the average power of demodulated symbols of the serving cell and on the respective average power of demodulated symbols of each of the dominant interfering cells, a channel condition indication is determined based on the metric value and the first function of the signal-to-interference ratio of the received signal, and the channel condition indication is transmitted to the cellular communication system, thereby providing downlink channel condition information to a network node. A method of creating a look-up table for mapping the first function and the metric value to the channel condition indication is also disclosed along with computer program products, arrangements and wireless communication devices corresponding to the methods.

Determination of channel condition indication

There is provided presence detection of a second transmit antenna port in a distributed antenna port system. Cell-specific reference signals, CRS, are received on a first receive antenna port and a second receive antenna port. The CRS have been transmitted by a first transmit antenna port and a second transmit antenna port in the distributed antenna port system. Reference signal received power, RSRP, measurements and reference signal resource element received power, RSRERP, measurements are estimated from the CRS. Presence is detected by comparing each one of at least one metric based on filtered RSRP measurements and filtered RSRERP measurements to a respective threshold.

Antenna port detection

Techniques for processing a received multi-code code-division multiple-access (CDMA) signal to detect unused spreading codes are disclosed. An example method includes, for each of a plurality of observation time intervals and for each of one or more candidate spreading codes, determining a detection threshold for use in detecting whether the candidate spreading code is unused in the received multi-code CDMA signal, based on a target detection sensitivity and at least one of an estimate of received signal quality and an estimate of channel estimation quality. Estimated signal power for the candidate spreading code is compared to estimated noise and interference power corresponding to a spreading code that is known to be unused or corresponding to a spreading code that carries known symbol values, using the calculated detection threshold. Whether or not the candidate spreading code is unused is then determined, based on the comparison.

Robust, fast unused-code detection

The invention relates to a methodperformed in a user equipmentfor estimating interference within a serving cellof a communication system. The user equipmentis connected to the serving celland the communication systemfurther comprising one or more neighboring cellsto the serving cell. The methodcomprises: receivingneighboring cell reference signals transmitted in at least one of the neighboring cellsand serving cell reference signals transmitted in the serving cell; and determininga first interference estimateof interference within the serving cell, the first interference estimate taking into account cancellation of interference from the neighboring cell reference signals. The invention also relates to a user equipment, computer program, and computer program product.

Method for estimating interference within a serving cell, user equipment, computer program and computer program products

When more than two layers are multiplexed in one CDM group, length-4 OCC has to be used across both clusters in one subframe. This means that slot-by-slot channel estimation according to conventional schemes cannot be exploited and Doppler impact cannot be well overcome. By introducing virtual variables and virtual channel samples that are used in processing two time slots in a subframe independently and applying a frequency domain filter based on the virtual variables and then performing postprocessing based on virtual channel samples, slot-by-slot processing is possible to reduce latency and overcome Doppler impact. Code de-spreading of length-4 OCC is no longer processed in time domain, but in frequency domain with two adjacent CDM subgroups. As a result, the frequency domain filtering can start earlier whereby detection latency and processing time for OCC of length longer than 2 is reduced. It can also be used for the length-2 OCC.

Low latency channel estimation for downlink MIMO

In one aspect of the teachings herein, a receiver generates an improved estimate of other-cell covariance for the data region of its own-cell signal, by supplementing its pilot-based estimations of the other-cell covariance with supplemental estimations of other-cell covariance that are determined from control symbols transmitted in the control region its own-cell signal and in one or more selected other-cell signals. While the supplemental estimations are derived from the control region, the receiver advantageously fits them against the pilot-based estimations or against received-signal correlations for the data region, and uses the fitted estimations to obtain an improved estimate of other-cell covariance, for use in generating combining weights for equalization processing of the own-cell signal.

Method and apparatus for equalization processing in a wireless communication receiver

A Reference Signal Received Power (RSRP) value is produced from a received Orthogonal Frequency Division Multiplexed (OFDM) signal that comprises a plurality of reference symbols located at known sub-carrier frequencies and times within the received OFDM signal. RSRP value production involves, for each hypothesized error state selected from a plurality of different hypothesized error states, ascertaining a corresponding hypothesized RSRP value, and then using the hypothesized RSRP values as a basis for determining a value for use as the produced RSRP value (e.g., by selecting a maximum one of the hypothesized RSRP values as the produced RSRP value). In this technology, each of the hypothesized error states is a hypothesized frequency error paired with a hypothesized timing error and the corresponding hypothesized RSRP value is produced by adjusting one or more measured channel estimates as a function of the hypothesized error state.

Cellular communication system computation of RSRP in the presence of large frequency errors

A method of transmitting communication signals to a plurality of targeted receivers includes transmitting one or more information streams for individual ones of the targeted receivers according to ongoing transmission scheduling, and controlling the ongoing transmission scheduling to reduce the number of impairment contributors that must be considered in received signal processing by scheduled ones of the targeted receivers. In one embodiment the controlling comprises scheduling the targeted receivers to avoid transmissions to more than one targeted receiver at a time. In the same or another embodiment, the controlling comprises at least one of using equal transmit power allocations for one or more information streams, and using fixed transmit power allocations for one or more of the information streams.

Method and apparatus for impairment correlation estimation in MIMO systems

The method disclosed herein is implemented in a radio receiver to detect an AWGN channel, where the radio receiver comprises a rake receiver. The radio receiver receives signals transmitted via a propagation channel from a transmitter, and determines that the propagation channel is an AWGN channel when a filtered version of a minimum value of a metric is lower than a threshold value. The metric relates to a difference between a normalized measured power profile of the propagation channel and a normalized power template, which normalized power template is dependent on predetermined sampling timing shifts and on rake finger positions within the rake receiver.

Radio receiver for detecting an additive white Gaussian noise channel

A receiver and method for receiving and processing a sequence of transmitted symbols in a digital communication system utilizing soft pilot symbols. A set of soft pilot symbols are transmitted with higher reliability than the remaining symbols in the sequence by modulating the soft pilot symbols with a lower order modulation such as BPSK or QPSK while modulating the remaining symbols with a higher order modulation such as 16 QAM or 64 QAM. The receiver knows the modulation type and location (time/frequency/code) of the soft pilot symbols, and demodulates them first. The receiver uses the demodulated soft pilot symbols as known symbols to estimate parameters of the received radio signal. Unlike traditional fixed pilots, the soft pilots still carry some data. Additionally, the soft pilots are particularly helpful in establishing the amplitude reference essential in demodulating the higher order modulation symbols.

Receiver and method for processing radio signals using soft pilot symbols

A multi-carrier linear equalization receiver, e.g., a RAKE receiver or chip equalization receiver, is described herein. The multi-carrier receiver distributes processing delays among a plurality of received carriers based on a dispersion determined for each carrier. The receiver initially allocates a minimum number of processing delays sufficient for light dispersion to each carrier. For the dispersive carriers, the receiver allocates one or more additional processing delays. In one embodiment, the additional processing delays are allocated to the dispersive carriers based on SIR.

Method and apparatus for allocating processing delays in multi-carrier systems

This disclosure is directed to a wireless receiver and a method for configuring the wireless receiver, comprising the actions of determining a geometry factor for a channel over which signals are transmitted to the wireless receiver, the geometry factor being a measure indicative of inter-cell interference plus noise power at the wireless receiver; determining the variance of the determined geometry factor, the variance being a measure indicative of the variation in time or rate of the geometry factor; and configuring the wireless receiver based on the geometry factor and the variance of the geometry factor.

Configuration of wireless receiver

In one aspect, the present invention provides for blindly detecting the presence of one or more secondary pilot signals that are not being used to serve a communication apparatus, such as a User Equipment (UE). Among its several advantages, the approach to blind detection taught herein provides robust detection performance, yet it requires relatively few receiver resources. The contemplated apparatus, in at least one example embodiment, uses its blind detection of secondary pilot signal(s) to trigger suppression of secondary pilot interference, for improved reception performance. In a particular, non-limiting example, the apparatus operates in an HSDPA-MIMO network in a non-MIMO mode and blindly detects secondary pilot signal energy associated with the supporting network providing MIMO service to nearby equipment.

Method and apparatus for blind detection of secondary pilot signal in a wireless communication system

Log-likelihood ratios produced by a decoder are incorporated into a soft symbol to soft bit estimation process and are used to perform improved channel estimation and impairment covariance estimation. In an example method, a plurality of soft bits and corresponding probability metrics for a series of received unknown symbols are generated. Estimates of the received unknown information symbols are then regenerated, as a function of the soft bits and corresponding probability metrics. An estimate of the average amplitude of the received unknown information symbols, or an estimate of the propagation channel response experienced by the received unknown information symbols, or both, are calculated, as a function of the regenerated symbol estimates. The results are applied to produce demodulated symbols for a second decoding iteration for the series of received unknown symbols.

Soft-bit generation and channel estimation for interference cancellation using decoder output

Techniques for obtaining smoothed channel response estimates in a communications receiver. An example method begins with obtaining ordered channel measurement samples for a current estimation interval and continues with the estimation of a short-term slope value for each of several sequential observation time intervals. A distortion metric is calculated for each of a plurality of candidate filter lengths, where each candidate filter length is an integer multiple of the uniform length. The distortion metric is based on the short-term slope values for observation time intervals falling within the candidate filter length, and characterizes the extent to which the candidate filter length will introduce tracking bias in subsequent signal processing. A filter length is then selected for use in demodulating a received signal from at least among the candidate filter lengths, based on the distortion metric values.

Estimating optimal linear regression filter length for channel estimation

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Malmö, Sweden

Elias Jonsson