Chip-to-symbol receiver despreader architectures and methods for despreading spread spectrum signals

Abstract

In a spread spectrum system, methods and despreader architectures for despreading the received spreaded codes with the use of a single correlator and a single correlation code is provided. Before despreading the incoming received spreaded codes, a single correlation code is generated using a symbol from a set of symbols that has been mapped into a set of differential encoded PN codes. Despreading output samples for each received spreaded code are obtained by correlating the received spreaded code with this single correlation code. Correlation is accomplished by multiplying each received sample of the received spreaded codes with the correlation code samples and accumulating the products of this multiplication. After correlation, the index for the maximum or minimum peak of the despreading output samples for each code is identified. This index can then be mapped into a symbol corresponding to the transmitted information. Corresponding despreader architectures comprise of a number of taps attached to a series of shift registers. Received samples of each received spreaded codes are inputted into the shift registers. The despreader architectures accumulates the products of multiplication of the value of the shift register with a predetermined value associated with each tap to produce the despreading output samples of a received spreaded code. It identifies the despreading output index producing the maximum of the absolute value of the despreading output and maps said index into a symbol corresponding to the transmitted information.