Abstract: An iterative arrangement of channel estimator (12), a Kalman filter unit (14), and a soft demodulator (16) 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 (12) 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.

Abstract: For each user in a multi-user detection arrangement in a CDMA communications system, a detector (80) provides a limiting function (88) 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 (84), or is multiplied by a multiplier inverse to an iteration index, to produce a derived signal. The derived signal is added (86) 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.

Abstract: 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.