A technique for minimizing the variance of interference in packetized interference-limited wireless communication systems

Wireless interference-limited communication systems utilizing direct-sequence (DS) code-division multiple-access (CDMA) signals are considered, for packet-based transmission of data of different statistics and variable bit rates. A scheme for packet transmission is proposed. The novelty of the scheme is in the fact that a packet is not transmitted in a continuous arbitrary-length time segment, but rather as a sequence of smaller data-units called packet-slots which are not necessarily neighboring each other. The position of a packet slot on the time axis is determined by hereby demonstrated packet-slot distribution patterns, and all packet slots are of the same length. Breaking packets into packet-slots introduces no additional overhead. The patterns are representable by unipolar binary codes/sequences whose properties based on number-theoretic proofs are reviewed. The proposed scheme can help reduce the time variability of the composite interference due to simultaneous transmissions of numerous DS-CDMA signals over the common frequency band. Exact probability distribution functions of the interference among different packet-slot distribution patterns are computable. By reducing the variance of the overall interference, the proposed scheme can contribute to increasing the system capacity which is one of the motivations for utilizing DS-CDMA signals in multipath fading environments