Research On Pseudo-noise Code Acquisition Technology Of Direct Sequence Spread Spectrum Communication Based On Software Radio

The Software Radio technology which has potential development is an new communication technology. Its application has broad prospect in mobile communication. For limited parts of an apparatus, the Software Radio technology is developed slowly. The Spread Spectrum Communication technology is mature and widely used in military and civil application. One kind of the communication is the direct Sequence Spread Spectrum communication which has good performance. When the Software Radio and the Spread Spectrum technologies combined, a new communication Platform is produced, that is the spread spectrum receiver based on Soft Radio which is more adaptive the wireless mobile communication world.In the system of the DSSS receiver based on Software Radio, PN code synchronization is the most important part. It can affect the receiver's performance. The synchronization of spreading code includes acquisition and tracking, thereinto, acquisition is more difficult and important. At present, practical implementation can be parallel, serial, or hybrid. And it can be viewed as time region, or frequency region. Also, it can be based on correlator, or matched filter. In substance, all of the technologies are similar for using the PN code self-correlation characteristic. When the locally generated PN code phase is correlated with the received-signal PN codes'and the threshold detector finds the max correlated peak value, the PN code acquisition is finished, and the followed is tracking.In this paper, two PN code acquisition systems in common use are modified for getting better performance. The theoretic research proves that the first modified system based on single integral sequence acquisition system has less acquisition-time in low SNR condition and the second modified system based on differential non-coherent matched filter system has 2dB SNR advantage at the same probability of false alarm and probability of detection, only increasing a delay cell. The simple modification improves the performance of the relevant receiver, so it is more suitable for the Software Radio receiver.