Abstract: In a multi user communication system, subcarriers are allocated to subchannels using a quality measurement for each subchannel. An initial sub carrier is allocated to each subchannel, and a quality metric measured. Subsequent subcarriers are allocated in dependence upon the quality measurement for each subchannel. The subchannel with the lowest quality measurement receives the first allocation, and the subchannel with the highest quality measurement receives the last allocation. The subsequent allocation is repeated, following a re-sort of the subchannel quality measurements, until all of the subcarriers are allocated.

Abstract: There is provided a first device for use in a communication system, the communication system further comprising a plurality of second devices, the system having a plurality of orthogonal frequency carriers available for transmissions, each second device having a respective carrier frequency offset estimated from signals received from the first device, each of the second devices transmitting a respective stream of symbols using the respective estimated carrier frequency offset and one or more frequency carriers selected from the plurality of orthogonal frequency carriers, the first device comprising receiver circuitry for receiving respective signals from each of the second devices; a channel estimator for generating, from the received signals, an estimate of the channel over which the signals have been transmitted; an interference estimator for generating, from the received signals, an estimate of interference at the first device caused by errors in the carrier frequency offsets estimated by each second devic

Abstract: There is provided a channel estimator for a receiver in a communication system, the channel estimator comprising an input for receiving signals that have been transmitted over a transmission channel; processing means for determining an initial estimate of the channel impulse response of the transmission channel from the received signals, the determined initial estimate comprising a plurality of taps; and determining a further estimate of the transmission channel from the initial estimate; wherein the processing means is configured to apply a weighting to a subset of the plurality of taps from the initial estimate in determining the further estimate, the value of the weighting being determined according to a quality of the received signals.

Abstract: There is provided a first device for use in a communication system, the communication system further comprising a plurality of second devices divided into a plurality of groups, the system having a plurality of orthogonal frequency carriers available for transmissions, each second device having a respective carrier frequency offset estimated from signals received from the first device, each of the second devices transmitting a respective stream of symbols using the respective estimated carrier frequency offset and one or more frequency carriers selected from the plurality of orthogonal frequency carriers, the first device comprising receiver circuitry for receiving respective signals from each of the second devices; a channel estimator for generating, from the received signals, an estimate of the channel over which the signals have been transmitted; an interference estimator for generating, from the received signals, an estimate of interference at the first device caused by errors in the carrier frequency off

Abstract: In a multi user communication system, subcarriers are allocated to subchannels using a quality measurement for each subchannel. An initial sub carrier is allocated to each subchannel, and a quality metric measured. Subsequent subcarriers are allocated in dependence upon the quality measurement for each subchannel. The subchannel with the lowest quality measurement receives the first allocation, and the subchannel with the highest quality measurement receives the last allocation. The subsequent allocation is repeated, following a re-sort of the subchannel quality measurements, until all of the subcarriers are allocated.

Abstract: In a multi user communication system, subcarriers are allocated to subchannels using a quality measurement for each subchannel. An initial sub carrier is allocated to each subchannel, and a quality metric measured. Subsequent subcarriers are allocated in dependence upon the quality measurement for each subchannel. The subchannel with the lowest quality measurement receives the first allocation, and the subchannel with the highest quality measurement receives the last allocation. The subsequent allocation is repeated, following a re-sort of the subchannel quality measurements, until all of the subcarriers are allocated.

Abstract: In a multi user communication system, subcarriers are allocated to subchannels using a quality measurement for each subchannel. An initial sub carrier is allocated to each subchannel, and a quality metric measured. Subsequent subcarriers are allocated in dependence upon the quality measurement for each subchannel. The subchannel with the lowest quality measurement receives the first allocation, and the subchannel with the highest quality measurement receives the last allocation. The subsequent allocation is repeated, following a re-sort of the subchannel quality measurements, until all of the subcarriers are allocated.

Abstract: Subchannel feedback is provided from a plurality of mobile devices to a base station in a communication system, in which a channel is divided into available subchannels. The base station first requests channel information from the mobile devices, and then receives the channel information, for example in the form of an average Effective Signal to Noise Ratio for the channel. Based on the received channel information, the base station selects a subset of the mobile devices, i.e. the best mobile devices. The base station then requests subchannel information relating to a subset of the available subchannels, from the selected subset of the mobile devices, and receives the subchannel information in the form of information identifying said subset of the available subchannels, without indicting a quality of said subset of the available subchannels.

Abstract: In a multi user communication system, subcarriers are allocated to subchannels using a quality measurement for each subchannel. An initial sub carrier is allocated to each subchannel, and a quality metric measured. Subsequent subcarriers are allocated in dependence upon the quality measurement for each subchannel. The subchannel with the lowest quality measurement receives the first allocation, and the subchannel with the highest quality measurement receives the last allocation. The subsequent allocation is repeated, following a re-sort of the subchannel quality measurements, until all of the subcarriers are allocated.

Abstract: A communication network comprises at least a first region serviced by a base station. This region also comprises a plurality of bridging stations deployed around the base station, so defining a circumference around it. Each bridging station comprises one or more directional antennas operable to generate a coverage area lying predominantly outside said circumference. The effect is to form, in operation, an outer zone predominantly outside said circumference serviced by said bridging stations, and an inner zone within said circumference serviced by said base station. For communications with the outer zone, said base station is operable to assign duplicate OFDMA sub-channels to mobile stations in respective areas of the outer zone served by bridging stations that experience sufficiently low levels of cross-interference from each other's communications.

Abstract: In a multi user communication system, subcarriers are allocated to subchannels using a quality measurement for each subchannel. An initial sub carrier is allocated to each subchannel, and a quality metric measured. Subsequent subcarriers are allocated in dependence upon the quality measurement for each subchannel. The subchannel with the lowest quality measurement receives the first allocation, and the subchannel with the highest quality measurement receives the last allocation. The subsequent allocation is repeated, following a re-sort of the subchannel quality measurements, until all of the subcarriers are allocated.

Abstract: An OFDM receiver includes an adaptive equalizer, which acts on a received signal, after conversion to digital samples. After filtering by the equalizer, any guard interval is removed, and a Fast Fourier Transform is applied to the signal. The data signal is then estimated and the estimated data is supplied as an output. The estimated data also has any guard interval reinserted, and is applied to an Inverse Fast Fourier Transform, and is fed back to the equalizer to allow adaptation of the tap coefficients thereof.