OVSF-CDMA code assignment in wireless ad hoc networks

Orthogonal Variable Spreading Factor (OVSF) CDMA code consists of an infinite number of codewords with variable rates, in contrast to the conventional orthogonal fixed-spreadingfactor CDMA code. Thus, it provides a means of supporting of variable rate data service at low hardware cost. However, assigning OVSF-CDMA codes to wireless ad hoc nodes posts a new challenge since not every pair of OVSF-CDMA codewords are orthogonal to each other. In an OVSF-CDMA wireless ad hoc network, a code assignment has to be conflict-free, i.e., two nodes can be assigned the same codeword or two non-orthogonal codewords if and only if their transmission will not interfere with each other. The throughput (resp., bottleneck) of a code assignment is the sum (resp., minimum) of the rates of the assigned codewords. The maxthroughput (resp., max-bottleneck) conflict-free code assignment problem seeks a conflict-free code assignment which achieves the maximum throughput (resp., bottleneck). In this paper,...

• Type: Conference
• Year: 2004
• Where: DIALM
• Authors: Peng-Jun Wan, Xiang-Yang Li, Ophir Frieder
• Keywords: Algorithms, Code Assignment, Conflict-free Code Assignment, DIALM 2004, Wireless Ad Hoc