Abstract: An active stream is selected from one of a plurality of audio streams generated in a common acoustic environment by obtaining, for each stream obtaining, at a series of measurement instants tn, where n=1 . . . N, a final performance metric that is representative of the stream's goodness for representing near-end speech at each measurement instant tn. The final performance metrics for each stream are accumulated to determine an overall performance score. A switch to a new stream as the active stream occurs when the stream with the best overall performance score exceeds the overall performance score of the currently active stream by a threshold amount.

Abstract: Processing requirements for acoustic echo cancellation in voice communications are significant and are even more so as the bandwidth of the communication increases. Whilst voice communication occupies a relatively narrow band of frequencies the processing requirements and so forth for wideband communication render acoustic echo cancellation difficult to achieve in a cost effective manner. The invention provides for acoustic echo cancellation within wideband communications by dividing the communications into sub-bands and applying acoustic echo cancellation to some sub-bands whilst processing other sub-bands according to the status of the communications. Additional sub-bands are transmitted at either full-duplex or half-duplex.

Abstract: Within audio telecommunications for audio-visual conferencing a means of reliable double-talk detection is required for several reasons, including control of residual echo, and control of adaptive algorithms used to estimate the echo. Existing techniques tend to either fail when echo return loss is very low or require highly complex algorithms to increase the range of detecting whether double-talk is occurring. The invention is based upon a new method of estimating the power envelope of the double-talk signal. This estimation is then employed in conjunction with a slightly modified version of an echo return loss enhancement (ERLE) based statistic, to form a double-talk decision based on a combination of the two statistics. The resulting decision rule works for both low-ERLE and high-ERLE situations, which is useful when there can be large variations in the magnitude of the echo path seen by the algorithms, or where near-end noise prevents the achievement of high ERLE.

Abstract: An active stream is selected from one of a plurality of audio streams generated in a common acoustic environment by obtaining, for each stream obtaining, at a series of measurement instants tn, where n=1 . . . N, a final performance metric that is representative of the stream's goodness for representing near-end speech at each measurement instant tn. The final performance metrics for each stream are accumulated to determine an overall performance score. A switch to a new stream as the active stream occurs when the stream with the best overall performance score exceeds the overall performance score of the currently active stream by a threshold amount.

Abstract: Processing requirements for echo cancellation in voice communications are significant and are even more so as the bandwidth of the communication increases. Whilst voice communication occupies a relatively narrow band of frequencies the processing requirements and so forth for wideband communication render echo cancellation difficult to achieve in a cost effective manner. The invention provides for provides echo cancellation within wideband communications by dividing the communications into sub-bands and applying echo cancellation to some sub-bands whilst processing other sub-bands according to the status of the communications. Additional sub-bands are transmitted at either full-duplex or half-duplex.

Abstract: Within audio telecommunications for audio-visual conferencing a means of reliable double-talk detection is required for several reasons, including control of residual echo, and control of adaptive algorithms used to estimate the echo. Existing techniques tend to either fail when echo return loss is very low or require highly complex algorithms to increase the range of detecting whether double-talk is occurring. The invention is based upon a new method of estimating the power envelope of the double-talk signal. This estimation is then employed in conjunction with a slightly modified version of an echo return loss enhancement (ERLE) based statistic, to form a double-talk decision based on a combination of the two statistics. The resulting decision rule works for both low-ERLE and high-ERLE situations, which is useful when there can be large variations in the magnitude of the echo path seen by the algorithms, or where near-end noise prevents the achievement of high ERLE.

Abstract: A method and apparatus of imparting coverage gain to cell-edge or cusp mobile subscribers without resort to diluted frequency reuse factors is disclosed. Each base station adopts a priori a beam illumination sequence designed to minimize or obviate the likelihood of beam clashes in a narrow beam adaptive beamforming system. Such sequences may be optimized to impact primarily cell-edge subscribers or subscribers within cusp areas of adjoining beams or sectors. The inventive protocols may be applicable to fixed multibeam systems as well as individual steered beam and spatial null generation antenna systems.

Abstract: A wireless communications system supporting multiple MIMO transmission modes supporting both diversity and directional transmissions under a plurality of different transmission modes comprises a plurality of transmit and receive antenna elements where the transmit antenna elements are arranged to provide polarization diversity. The transmitting station derives actual knowledge of the forward channel by feeding back certain information such as a preferred beam index and a channel quality indicator figure of merit for that beam from the receiving station to the transmitting station along a reverse channel. The receiving station knows the beam weights used by the transmitting station. The transmitting station applies the fed back information to transmit user data intended for the receiving station in the optimal fashion, such as along the preferred beam and at a time when forward channel conditions are satisfactory.