As the wireless telecommunications industry becomes more widely accepted, the need for mobile data communication has followed the rise in mobile voice communication. Cellular Digital Packet Data (CDPD) offers an unobtrusive data service that overlays the existing Advanced Mobile Phone Service (AMPS) in a cost effective manner that will be attractive to most service providers. Using idle time between voice traffic, CDPD uses Gaussian Minimum Shift Keying (GMSK) to send bursts of Reed-Solomon encoded information while channel hopping to avoid interfering with voice transmissions. This thesis assesses the performance of CDPD for different channel environments through simulation. Specifically, Gaussian noise, Rayleigh fading, co-channel interference models are incorporated to identify the performance of the system. / Master of Science

In this thesis, symbol timing recovery based on matched filtering in Gaussian Minimum Shift Keying (GMSK) with bandwidth-bit period product (BT) of 0.3 is investigated. GMSK is the standard modulation type for GSM. Although GMSK modulation is non-linear, it is approximated to Offset Quadrature Amplitude Modulation (OQAM), which is a linear modulation, so that Maximum Likelihood Sequence Estimation (MLSE) method is possible in the receiver part. In this study Typical Urban (TU) channel model developed in COST 207 is used. Two methods are developed on the construction of the matched filter. In order to obtain timing recovery for GMSK signals, these methods are investigated. The fractional time delays are acquired by using interpolation and an iterative maximum search process. The performance of the proposed symbol timing recovery (STR) scheme is assessed by using computer simulations. It is observed that the STR tracks the variations of the frequency selective multipath fading channels almost the same as the Mazo criterion.