Gold codes,Hadamard partitions and the security of CDMA systems |
| |
Authors: | Derek H Smith Richard P Ward Stephanie Perkins |
| |
Institution: | (1) Division of Mathematics and Statistics, University of Glamorgan, Pontypridd, CF37 1DL, Wales, UK |
| |
Abstract: | Let V = {1, 2, . . . , M} and let be a set of Hadamard matrices with the property that the magnitude of the dot product of any two rows of distinct matrices
is bounded above. A Hadamard partition is any partition of the set of all rows of the matrices H
i
into Hadamard matrices. Such partitions have an application to the security of quasi-synchronous code-division multiple-access
radio systems when loosely synchronized (LS) codes are used as spreading codes. A new generation of LS code can be used for
each information bit to be spread. For each generation, a Hadamard matrix from some partition is selected for use in the code
construction. This code evolution increases security against eavesdropping and jamming. One security aspect requires that
the number of Hadamard partitions be large. Thus the number of partitions is studied here. If a Kerdock code construction
is used for the set of matrices, the Hadamard partition constructed is shown to be unique. It is also shown here that this
is not the case if a Gold (or Gold-like) code construction is used. In this case the number of Hadamard partitions can be
enumerated, and is very large.
|
| |
Keywords: | Gold codes Hadamard matrices Loosely synchronized codes |
本文献已被 SpringerLink 等数据库收录! |
|