Telefonaktiebolaget Lm Ericsson (publ)

Bjorn O Gudmundson

Ulf Goran Forssen

Bengt Y Persson

Karim Jamal

Hakan O Eriksson

Gustav Brismark

Alex Krister Raith

Jonas B Karlsson

Sara Mazur

Olof E Grumlund

Mobile stations using antenna diversity are described. Techniques for combining CDMA signals received over plural antennas at a mobile unit are provided which suppress interference from undesired base stations.

Mobile station having plural antenna elements and interference

In a digital signal transmission system, a receiver receives a signal, wherein the signal bandwidth of the system exceeds the system symbol rate. A correlation and sampling circuit receives a baseband signal, samples the signal eight times per symbol time, correlates, generates a channel estimate and down-samples the sampled signal to form an observed signal. This signal is filtered in a prefilter, whose output is sampled at symbol rate and the obtained signal is delivered to a channel equalizer which performs a viterbi algorithm with non-quadratic metric calculation and generates estimated symbols. A channel estimation filter receives a symbol sequence which contains alternate zero-value symbols and the estimated symbols and generates an estimated signal. An error signal is generated and used to adapt the channel estimate and also to generate weight factors. The coefficients of the prefilter are generated as a function of the channel estimate and the weight factors. Coefficients are generated in a metric calculation filter, by convolving the channel estimate with the prefilter and are used to generate the estimated symbols. The transmission channel, excluding the prefilter, is estimated explicitly so as to enable fast channel changes to be followed. The use of the weight factors enables a short channel estimate to be used. The insertion of the zero-value symbols simplifies adaptation of the channel estimate.

Method and device for estimating transmitted signals in a receiver in

A method and apparatus for transmitting and receiving signals in a base station with an antenna array in a cellular communication system. The available communication channels are divided into a plurality of classes. The base station transmits signals to the mobile station in a first class of channels in a wide antenna lobe. The position of a mobile station can then be determined from signals received at the base station from the mobile station. After the position of the mobile station has been determined, the base station can transmit signals to and receive signals from the mobile station in a second class channel with a narrow antenna lobe.

Method and apparatus for transmitting and receiving signals using two

A transceiver for improving the spectral efficiency and the capacity of cellular communication systems is disclosed. The transceiver uses an antenna array for communicating in a cellular communication system with a plurality of mobile stations. In addition, the transceiver contains a spatial filter connected to an antenna array wherein the spatial filter has as many outputs as there are array elements and as many inputs as there are spatial channels. A splitter then splits data to be transmitted to each mobile station into a number of parallel data streams, the number of parallel data streams corresponds with the number of spatial channels in the system, wherein the data streams, are delayed based upon uplink measurements. Finally, power allocators are provided for allocating transmission power to each possible channel based upon long-term SNR measurements on the uplink.

Transceiver algorithms of antenna arrays

A communication system having a frequency hopping scheme which provides an improved initial synchronization in mobile stations of control channels. Special synchronization bursts are inserted into the hop sequence of the control channels which, when decoded, give the mobile station the hop sequence to follow for the control channel.

Frequency hopping control channel in a radio communication system

A method of effecting handover in a mobile telephone system comprising fixed base stations and mobile stations. The system includes several layers of radio cells, where a cell in a given layer covers several cells in a nearest underlying or subordinate layer. A mobile station moving in a microcell may find it difficult to handover to another microcell in the same cell layer, when the signal strength of the established connection in the first microcell is rapidly weakened. No information concerning the target base station can be transmitted. According to the proposed method, handover is effected to a cell in the nearest overlying cell layer, a so-called umbrella cell, either permanently (the mobile is moving quickly) or temporarily (the mobile is moving slowly). In the latter case, handover is made back to a microcell. The handover command is either transmitted from the base station of the microcell having elevated power, or from the target base station.

Method of effecting handover in a mobile multilayer cellular radio system

A Code Division Multiple Access (CDMA) communication system which allocates different sets of frequencies to cells with different transmission power levels. Based upon the transmission power levels of a base station for each cell, each base station is assigned to one of at least two groups of base stations. Each group of base stations is assigned a set of frequencies for traffic communication. The set of frequencies assigned to one group of base stations does not overlap with the set of frequencies assigned to a different group of base stations.

CDMA frequency allocation

A method and system for increasing the capacity of radiotelephone communication systems by eliminating interference to communication traffic caused by random access bursts from unconnected mobile station are disclosed. Access slots are provided in CDMA signals by interrupting other communication traffic of mobile stations using the same frequency at periodic intervals. This allows mobile access bursts to be received at a base station without interfering with other traffic.

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Sollentuna, Sweden

Bjorn O Gudmundson