Abstract: In a decoder implementing a belief propagation algorithm for iteratively decoding a Low Density Parity Check (LDPC) encoded data block, a method of computing messages to be sent by a first node of the decoder to at least one neighbour node of the decoder. The method comprises: processing messages received by the first node to remove an echo of a previous message sent by the first node to the at least one neighbour node in a previous iteration, to yield corresponding modified messages; computing a message for a current iteration using the modified messages; and broadcasting the computed message for the current iteration to each of the at least one neighbour nodes.

Abstract: Soft-handoff methods involve receiving an uplink signal from a user equipment at more than one basestation. The uplink signals are processed at each basestation before being backhauled to a common point for use to derive a single signal from the user equipment. One problem with previous types of soft-handoff methods is that relatively complex processing is required at each basestation in order to demodulate and decode the signals. It is also desired to further increase uplink capacity as compared with known types of soft-handoff methods. This is achieved by backhauling signals without carrying out any decoding of the uplink signal at the basestation. The backhauled signals are combined at a common point using maximal ratio combining before being fully demodulated and decoded. As a result capacity is increased and required user equipment transmit power is reduced.

Abstract: In a cellular mobile telecommunications system the position of a mobile station can be estimated in terms of its bearing and range from a cell site. A multi-element direction finding antenna at the cell site receives signals from the mobile station and a receiver circuit estimates the bearing using the relative phase of signals received at different antenna elements and estimates the range by measuring round trip delay of signals to and from the mobile station. Motion of the mobile station can introduce errors into the bearing estimate due to frequency offset and frequency spread when element sampling is non-simultaneous. Compensation for these errors is introduced by using signal samples successively received at the same antenna element to estimate Doppler frequency offset and spread. It is necessary to ensure accurate calibration of the direction finding antenna and the receiver circuit.

Abstract: A method for synchronous code division multiple access (SCDMA) scheduling including intelligent uplink SCDMA scheduling that incorporates polarization and/or spatial information to determine SCDMA code set assignment. The method includes scheduling algorithms to reduce observed interference and thus allow for a potentially significant increase in uplink capacity. This allows more terminals to be accommodated within a single site (i.e., higher sustainable user density) and/or a reduction in the number of base stations that must be deployed in order to cover a given area. This present invention is applicable to any high-speed wireless evolution SCDMA-based data system that would require highly efficient and optimized scheduling algorithms.

Abstract: Soft-handoff methods involve receiving an uplink signal from a user equipment at more than one basestation. The uplink signals are processed at each basestation before being backhauled to a common point for use to derive a single signal from the user equipment. One problem with previous types of soft-handoff methods is that relatively complex processing is required at each basestation in order to demodulate and decode the signals. It is also desired to further increase uplink capacity as compared with known types of soft-handoff methods. This is achieved by backhauling signals without carrying out any decoding of the uplink signal at the basestation. The backhauled signals are combined at a common point using maximal ratio combining before being fully demodulated and decoded. As a result capacity is increased and required user equipment transmit power is reduced.

Abstract: In a cellular mobile telecommunications system the position of a mobile station can be estimated in terms of its bearing and range from a cell site. A multi-element direction finding antenna at the cell site receives signals from the mobile station and a receiver circuit estimates the bearing using the relative phase of signals received at different antenna elements and estimates the range by measuring round trip delay of signals to and from the mobile station. Motion of the mobile station can introduce errors into the bearing estimate due to frequency offset and frequency spread when element sampling is non-simultaneous. Compensation for these errors is introduced by using signal samples successively received at the same antenna element to estimate Doppler frequency offset and spread. It is necessary to ensure accurate calibration of the direction finding antenna and the receiver circuit.

Abstract: A base station of a cellular communications system forms a plurality of adjacent overlapping beams in azimuth across a coverage area, and the position of the plurality of beams is varied in unison about a rest position whereby to provide a mean antenna gain in all azimuthal directions across the coverage area and to minimise cusping loss. The position of the beams can be varied by a movement in azimuth over one half, or multiples of one half, of the angular separation of the formed beams. Preferably there are a plurality of base stations in the system, each of whose plurality of beams are varied in position independently of the other base stations. The beams can be varied at a rate which is substantially equal to the rate of variation of one of the effects normally experienced by a terminal, and which the system operator incorporates a margin to accommodate.

Abstract: In a cellular radio communications system, using for example spread-spectrum communication, handoff between signals in different cells or in different sectors of sectored cells can be used to provide diversity reception at a mobile station and at cell sites and so to improve the reliability of data decoding. In sectored cells the diversity between signals in adjacent sectors can be low if the fading of the signals is correlated. The invention thus improves diversity gain by prioritising handoff between sectors or cells providing or expected to provide greater signal diversity over handoff between sectors providing or expected to provide less signal diversity, such as between adjacent sectors in sectored cells. Signals are therefore selected for diversity combining on the basis of both signal strength and signal diversity.

Abstract: A conventional antenna 114 at a cell site of a sectored cell in a cellular radio communications system has a low angle of coverage in elevation and therefore has low gain for close-in subscriber units (near the cell site). In a sectored cell, a main beam antenna in a first sector generates sidelobes and backlobes which may fall within the close-in area in other sectors. A close-in mobile in one of the other sectors may move into such an out-of-sector lobe and cause unexpected interference to the base station transceiver (BTS) of the first sector. A downward-looking antenna (DIA) 110 supplements the conventional antenna in each sector and has a beam 112 covering the close-in area. The gain of the DLA beam is greater than that of any out-of-sector lobes and so provides a subscriber unit with a higher gain link to the BTS of its own sector than is provided by out-of-sector lobes to the BTS of any other sector.