Acquisition in direct-sequence spread-spectrum communication networks: an asymptotic analysis

The effect of multiple-access interference on the acquisition of direct-sequence spread-spectrum (DS/SS) signals is studied. A passive matched filter approach is used, and the acquisition window length, which is the length of the matched filter, determines the complexity of the acquisition scheme. The acquisition-based capacity of a DS/SS system is defined to be the maximum number of simultaneous transmissions permissible while maintaining acceptable acquisition performance. The performance of the acquisition scheme is evaluated for large acquisition window length, and the asymptotic analysis yields the capacity as a function of the acquisition window length. If this length is linearly related to the processed gain, the acquisition-based capacity is smaller than that obtained by consideration of post-acquisition criteria only (e.g., bit-error probability for the demodulated signal). The results indicate the relative importance of the acquisition problem and suggest directions for further research