An adaptive symbol timing synchronization method for multi-mode & multi-service software radio communications system

A symbol timing synchronization method is proposed for the realization of a multi-mode and multi-service software radio receiver. The method enables a n accurate search for the optimum symbol timing without ally redundant hard ware such as sampling rate conversion devices. when the system clock is non -integer times for the target systems' symbol rates. Accordingly, a multimo de and multi-service receiver can set an arbitrary system clock for the tar get system's symbol rates, and the number of A/D converters call bo reduced to the minimum. Also, it may lead to a reduction of tile implementation ti me for digital signal processing hardware, and reduce the burden on the mem ory in a multi-mode and multi-service software radio receiver, since no sam pling rate conversion is needed. Thf effectiveness of the proposed method f or use with a multi-mode and multi-service software radio receiver for futu re ITS services. which are CPS (Global Positioning System). ETC (Electric T oll Collection system), and Japanese PHS (Personal Handy-phone System) is a ssumed, and the supposed system is evaluated by computer simulation. The ji tter performance under an AWGN (Additive White Gaussian Noise) environment is first simulated, and the necessary number of over-samples and observatio n symbols are defined bq the value of jitter which gives a theoretical valu e of the BER, respectively. Moreover, the bit error rate performance under a fading environment condition where the attenuation of a signal level fluc tuates more rapidly than in a noise environment is calculated, and it is sh own that the proposed method enables an accurate search for the optimum syn chronization timing caused by a cycle slip even if the signal level is quit e low, and allows one handset to adopt a system clock for several systems.