Link Adaptation and Recursive Estimation for GPRS Wirless Networks

In most of the mobile or cellular systems, the height of the mobile antenna may be much lower than the surrounding structures. Thus, the existence of a direct or line of sight path between the transmitter and the receiver is highly unlikely. In such a case, propagation is mainly due to reflection and scattering from the buildings and by diffraction over and/or around them. So, in practice, the transmitted signal arrives at the receiver via several paths with different time delays creating a multipath situation at the receiver, these multipath waves with randomly distributed amplitudes and phases combine to give a resultant signal that Fluctuates in time and space. The phenomenon of random fluctuations in the received signal level is termed as fading. The existing system determines the signal from the received signal based on the mean distance method, which fails in proper estimation under high fading and high Doppler shift effect. With the increasing use of portable devices such as Personal Digital Assistants (PDA), laptops, voice and data integrated cell phones etc communication methods use atmosphere as the medium to transmit and receive information between terminals. This paper deals with the implementation of an enhancement to the existing demodulation technique using Bayesian Demodulation for the physical layer simulation of a General Packet radio services (GPRS) system considering variable Rician fading and variable Doppler effect for an AWGN channel .The system performance is evaluate based on Bit Error Rate (BER) and Signal to Noise Ratio (SNR) for the realized GPRS system