Abstract: A method, a system and a computer program product for fast detection of the onset of a near-end signal is provided. An Acoustic Echo Canceller (AEC) attenuates an acoustic echo present in a tele-communication network. The AEC includes an adaptive filter that estimates the acoustic echo and generates an error signal. The error signal is the difference between the acoustic echo and the estimate of acoustic echo plus a near-end signal, if present. The method comprises computing an onset indicator parameter from the error signal and the estimate of acoustic echo. Several other parameters are subsequently calculated by using the onset indicator parameter, the error signal and the estimate of acoustic echo. The presence of the near-end signal is detected with very low detection delay by using the parameters mentioned above and one or more threshold values.

Abstract: A method and system for low-complexity implementation of a Viterbi Decoder with near optimal performance has been disclosed. The Viterbi decoding technique is diagrammatically represented as a trellis. The trellis includes various states at different time instants, and branches connecting these states. Each state has an associated state metric and a survivor path sequence, whereas each branch has a branch metric. The state metric for each current state is checked for crossing a predefined limit. If it crosses the predefined limit, the state metric is updated with a new metric that is obtained by subtracting a constant value from the state metric. Thereafter, the method finds a common path in the trellis at each state and updates the survivor path sequence of each state. The Most Significant Bits (MSBs) of the survivor path sequences of the states at a particular time instant are computed and the original data is decoded, based on the count of ‘0s’ and ‘1s’ in the MSBs.

Abstract: A method, system, and computer program product for frame and frequency synchronization in packet-based Orthogonal Frequency Division Multiplexing (OFDM) in wireless digital communication systems. An OFDM packet includes a preamble preceded by a Cyclic Prefix (CP). The method includes computing a timing metric for packet-based OFDM. The timing metric yields a sharp peak at a preamble boundary. The preamble boundary is detected, based on a threshold. The threshold is determined a priori, based on mean and variance of the timing metric at the preamble boundary and in its neighborhood. The mean and the variance are evaluated for an Additive White Gaussian Noise (AWGN) channel. The detection of the preamble boundary enables frame synchronization in packet-based OFDM. The method further involves the task of frequency-offset estimation, using the preamble. The frequency-offset estimation enables frequency synchronization in packet-based OFDM.

Abstract: Various embodiments of the present invention relate to a method and system for Vertical Bell Layered Space-Time (V-BLAST) detection with near Maximum Likelihood (ML) performance and low complexity. The V-BLAST system is a Multiple-Input Multiple-Output (MIMO) system. A receiver is provided that detects the data transmitted from the multiple transmitting antennas. The detection performance of such a method and system is better than that of linear receivers while keeping the complexity of the receiver marginally higher than that of the linear receivers. The detection performance of such a method and system is very close to that of the ML receiver while its complexity is much less than that of the ML receiver.