Kabushiki Kaisha Toshiba

Toshiba Corporation

Khurram Ali Rizvi

Yuk Ching Chow

Michael Philip Fitton

Tomoya Horiguchi

Mohamed Rafiq Ismail

Anthony Craig Dolwin

The present invention provides a method of improving the performance of a CDMA based wireless network, such as a 3G cellular network for example. Interference cancellation is effectively performed earlier by using the channel request such as a reservation packet from a mobile terminal to estimate interference from that mobile on existing mobile users and interference on the mobile from existing mobile users, by determining the relative transmission timing of the new mobiles channel request compared with the transmission timings of the existing mobiles. The base station determine the cross-correlation between the codes already assigned to the existing users and the code to be allocated to the new user in order to determine an interference measure. This interference can then be cancelled from the new mobile when its data packets are received.

Uplink interference cancellation

Spread spectrum receiver architectures and methods are described for reducing interference, particularly the interference observed at a user-end terminal in a W-CDMA 3G mobile communications system. Interpath interference which arises due to non-zero cross and auto correlation of more than one spreading code is suppressed by estimating a transmitted signal stream, or a plurality of such signal streams in the case of a plurality of multipath components, respreading this estimated signal and subtracting non-orthogonal interference contributions from a received signal. The techniques provide an improved bit error rate or equivalently, enhanced capacity for a digital mobile communications network.

Receiver processing systems

A multicode receiver for receiving data carried by a plurality of spread spectrum signals having a corresponding plurality of spreading codes, the spreading codes being substantially mutually orthogonal, the receiver having intercode interference suppression, the receiver including a multicode spread spectrum receiver to provide a set of data estimates having a plurality of estimates of data carried by the plurality of spread spectrum signals, one estimate for each spread spectrum signal, a plurality of respreaders to respread the plurality of data estimates, a plurality of interference suppressers, at least one for each of the plurality of spreading codes, each at least one interference suppresser for each code being configured to suppress respread data estimates for the spread spectrum signals of the other codes, from a received signal, a plurality of rake fingers each having the plurality of interference suppressers, and a plurality of rake combiners, one for each of the plurality of spreading codes.

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Bristol, United Kingdom

Khurram Ali Rizvi