Patent ID: 7197007
Filing Date: 2007-03-27
Classification: H04J,H04L

Abstract:
1. A method for wireless communications comprising: providing a multicarrier direct-sequence code-division multiple-access (MS-DS/CDMA) communications system; generating a code tree of two-dimensional orthogonal variable spreading factor (2D-OVSF) codes, wherein each node of the code tree has a corresponding matrix; selecting an M×N matrix from a node of the code tree, where M relates to the number of available frequency carriers in the MS-DS/CDMA system, N relates to a spreading factor, M=2 assigning the M×N matrix to a MS-DS/CDMA-enabled device of the MS-DS/CDMA system to serve as a signature sequence of the device; wherein generating the code tree comprises: providing a first set of orthogonal 2×2 matrices providing a second set of orthogonal 2×2 matrices utilizing the first set of 2×2 matrices to generate a pair of progenitor nodes in the code tree that respectively represent matrices A utilizing the matrices A wherein {circle around (×)} is a Kronecker product, and children nodes of the code tree correspond to data transmission rates that are slower than those of parent nodes, thereby transmitting multirate transmissions by utilizing orthogonal matrices in the code tree.