Spreading code sequence acquisition system and method that allows fast acquisition in code division multiple access (CDMA) systems

摘要

Methods for generating code sequences that have rapid acquisition properties and apparatus which implement the methods by processing spreading codes on in-phase and quadrature channels. A first method combines two or more short codes to produce a long code. This method may use many types of code sequences, one or more of which are rapid acquisition sequences of length L that have average acquisition phase searches r=log2L. Two or more separate code sequences are transmitted over the complex channels. If the sequences have different phases, an acquisition may be done by acquisition circuits in parallel over the different code sequences when the relative phase shift between the two or more code channels is known. When the received length L codes or the length L correlation codes used to find the phase of the received codes have a mutual phase delay of L/2, the average number of tests to find the code phase of the received code is L/4. The codes sent on each channel may be the same code, with the code phase in one channel being delayed with respect to the other channel, or they may be different code sequences.