Abstract: The invention is directed to techniques for space-time coding in a wireless communication system in which the transmitter makes use of multiple transmit antennas. The transmitter uses channel information estimated by a receiving device and returned to the transmitter, e.g., as feedback. In one exemplary embodiment, the transmitter receives a mean feedback information that defines a mean channel value associated with the different channels of the different antennas. In another exemplary embodiment, the transmitter receives covariance feedback, e.g., statistical values associated with each of the different channels.

Abstract: In general, joint error-control coding and linear precoding techniques are proposed for fading-resilient transmissions over frequency- at and frequency-selective fading channels encountered with high-rate wireless OFDM transmissions. For example, a wireless communication system includes a transmitter that applies non-linear codes and a linear precoder to a data stream to produce a joint coded-precoded waveform. A receiver receives the joint coded-precoded waveform from the transmitter via a wireless communication channel, and demodulates the joint-coded precoded waveform to produce estimated data. The combination offers a multiplicative benefit to the diversity achievable by the wireless communication system.

Abstract: Techniques are described for space-time block coding for single-carrier block transmissions over frequency selective multipath fading channels. Techniques are described that achieve a maximum diversity of order NtNr (L+1) in rich scattering environments, where Nt (Nr) is the number of transmit (receive) antennas, and L is the order of the finite impulse response (FIR) channels. The techniques may include parsing a stream of information-bearing symbols to form blocks of K symbols, preceding the symbols to form blocks having J symbols, and collecting consecutive Ns blocks. The techniques may further include applying a permutation matrix to the Ns blocks, generating a space-time block coded matrix having Nt rows that are communicated through a wireless communication medium. The receiver complexity is comparable to single antenna transmissions, and the exact Viterbi's algorithm can be applied for maximum-likelihood (ML) optimal decoding.

Abstract: Techniques are described for efficiently estimating and compensating for the effects of a communication channel in a multi-carrier wireless communication system. The techniques exploit the fact that the transmitted symbols are drawn from a finite-alphabet to efficiently estimate the propagation channel for multi-carrier communication systems, such systems using OFDM modulation. A transmitter transmits data through a communication channel according to the modulation format. A receiver includes a demodulator to demodulate the data and an estimator to estimate the channel based on the demodulated data. The channel estimator applies a power-law operation to the demodulated data to identify the channel. The techniques can be used in both blind and semi-blind modes of channel estimation.

Abstract: Techniques are described for maintaining the orthogonality of user waveforms in multi-user wireless communication systems, such as systems using the code division multiple access (CDMA) modulation scheme in the presence of frequency-selective fading channels. Unlike conventional systems in which spreading is performed on individual information-bearing symbols, the “chip-interleaved block-spreading” (CIBS) techniques described herein spread blocks of symbols. A transmitter includes a block-spreading unit to form a set of chips for each symbol of a block of information-bearing symbols and to produce a stream of chips in which the chips from different sets are interleaved. A pulse shaping unit within the transmitter generates a transmission signal from the stream of interleaved chips and transmits the signal through a communication channel.