Nortel Networks Corporation

Other

Yuri S Shinakov

Vitali B Kreindeline

Mikhail G Bakouline

Alexandre M Chloma

Wen Tong

Rui R Wang

Chao Wang, Legal Representative

Ming Jia

Jian Cui

Zhi Ding

Alexander M Shloma

Mikhail Germanovich Bakulin

Vitally Kreyndelin

Tong Wen

Mohamed El-Tarkhuni

Philip Thomas

Alexandere M Chloma

Chao Wang

Space-time diversity using a plurality of transmit antennas is provided with a turbo coding arrangement comprising two recursive systematic convolutional coders, to one of which input bits are supplied directly and to the other of which the information bits are supplied after interleaving of bit groups for respective symbol intervals. Symbols produced by the coders and comprising systematic and parity information are supplied to paths to the antennas alternately in successive symbol intervals to provide the space-time diversity. Arrangements are described for 2 and 4 antennas and for various convolutional codes, and an iterative decoder is also described.

Methods and apparatus for turbo space-time trellis coding

An iterative arrangement of channel estimator (), a Kalman filter unit (), and a soft demodulator () is provided for producing an estimate of complex gain of a CDMA communications channel carrying data and pilot channels, and demodulated data of the data channel. An initial channel estimate is produced by the estimator () using only the low-power pilot channel. This later is improved by the iterative process using the data channel. The complex gains is represented by a sum of sinusoidal signals with different frequencies and randomly variable amplitude and phase.

Channel estimation in CDMA communications systems using both lower power pilot channel and higher power date channel

For each user in a multi-user detection arrangement in a CDMA communications system, a detector () provides a limiting function () responsive to a combined signal to produce a detection signal, having any of at least three possible values, for supply to a signal regenerator, regenerated signals being subtracted from a received signal in successive detection iterations of the multi-user detection arrangement. A code correlated signal is supplied via an inverse hyperbolic tangent function (), or is multiplied by a multiplier inverse to an iteration index, to produce a derived signal. The derived signal is added () to a representation of a detection result stored from a previous iteration to produce the combined signal. The limiting function can comprise a hyperbolic tangent function.

Multi-user detection in CDMA communications system

In a transmitter of a wireless communications system having M transmit antennas (), each transmit antenna is supplied with a respective combined signal comprising a respective one of M groups each of N data sub-streams, orthogonally spread by N Walsh code sequences (Wto WN). The N orthogonal code sequences used for each of the M groups comprise a respective one of M different combinations of N from Northogonal code sequences, where N&#x3e;N. M and N are integers greater than one. The combined signals can also include orthogonally spread pilot signals (WP) for channel estimation at a receiver. Orthogonality of the signals transmitted from the transmit antennas is increased, so that transmit signal power can be decreased and/or the receiver can have fewer than M receive antennas.

Transmitter for a wireless communications system using multiple codes and multiple antennas

An impulse response matrix of a received signal in a TDMA communications system is approximated using a plurality of indirect variables of a linear complex vector. The indirect variables are used for synchronizing to the received signal and for tracking and frequency offset estimation during successive samples of the received signal, the samples being equalized in dependence upon the indirect variables. A demodulated signal is derived from the equalized received signal samples. Individual synchronization and tracking units, and a single equalizer, can be provided for a two-antenna receiver. Tracking errors can be used to adapt a parameter of the equalizer to reduce interference in the received signal.

Cellular communications system receivers

Systems and methods for interleaving codes includes a processor that acts on a data frame received and stored in a memory. The processor separates portions of the data frame and permutes the portions, achieving maximum data scattering by using equations based on number theory.

Interleavers for turbo code

An encoder for a wideband CDMA communications system comprises an outer Reed-Solomon code encoder and an inner parallel concatenated convolutional code (PCCC) or turbo code encoder. An iterative PCCC decoder, for decoding the inner code, includes summing functions in forward and feedback paths for producing extrinsic information to enhance soft decoding decisions by first and second decoders in successive decoding iterations. An outer code decoder connected following the PCCC decoder also can provide serial feedback information for enhancing iterative decisions by the PCCC decoder.

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Moscow, Russia

Yuri S Shinakov