Automated threshold control for acquisition in spread spectrum packet radio communication

A novel automated threshold control (ATC) scheme for acquisition in direct-sequence spread-spectrum packet radio systems using a matched filter receiver is described. For received packets with different SNRs, the ATC algorithm is able to find a desired threshold value in one pseudonoise code period such that the probability of false acquisition is minimized and the probability of correct acquisition is maximized. It is shown that the proposed AT acquisition scheme is robust for receiving packets with a large amplitude dynamic range. Compared with the conventional constant threshold acquisition scheme, the new scheme only needs a few more logic units and a small memory unit for its implementation. A potential application of this algorithm is for code division multiple access (CDMA) systems where the equivalent SNRs of received packets fluctuate according to the amount of cochannel interference