A Study Of Multipath Mitigation On Spread-Spectrum Communication Geolocation System With Space-Time Modulation

To meet the challenge of future communication and integrated communication and radiolocation system, it is analyzed that how to receive space-time signal and obtain location information under multi-path environment in a spread-spectrum space-time modulation system, which is an integrated communication and radiolocation system with circular array antenna. Two techniques of pseudo-random code tracking relying on delay lock loop (DLL) and separation of sub-chip multi-path components are studied as follows.According to the first technique, the expression of open-loop measurement compensation and a new multi-loop iteration algorithm are deduced based on previous research, and the following research on the second technique consists of several parts. First, a simple method is proposed suitable for separation of sub-chip multi-path component and the influence of tracking errors on the separation of sub-chip multi-path components under spread-spectrum communication model is discussed in detail, then some certain researches on joint-estimation of pseudo-random code tracking and sub-chip multi-path components are carried out, which combine a simple new algorithm for extracting multi-path components and a sort of estimation of multi-path channel pulse response in presence of multi-path interference. Finally, this kind of joint-estimation is applied to the system, and the results of the simulation demonstrate that the accuracy of direction-finding and ranging is improved after adopting the method.