The Impact of Doppler Shift On the OSTBC System In Vehicular Channel Condition
In ITS communicating systems, the transmitter and receiver are moving at high speeds. This causes different fading statistics depending on the existence of a line-of-sight (LOS). Rician channel model can be considered as a suitable probabilistic channel model for the vehicular network in the highway scenario. On the other side, Rayleigh channel model can be considered as a suitable probabilistic channel model for the vehicular network in the traffic scenario. Multiple-input multiple-output antennas at the transmitter and receiver side enhanced the BER performance of wireless communication systems. MIMO channels between transmit and receive antennas are statistically independent identically distributed channels. In real life, the channels are correlated and the MIMO gains are not always be reachable. Hence, spatial correlation between a signal's spatial direction and the average received signal gain exists. In a vehicular scenario, transmit and receive antennas are mounted at heights of 1–3 meters. Vehicles and buildings are in close proximity which can be very close to one antenna but far from the others. Therefore, the channels are probably non-identically distributed. In this paper, we present a brief analysis on the effect of high mobility patterns on the bit error rate (BER) performance of Orthogonal Space Time Block Coding (OSTBC) and Trellis Code Modulation (TCM) in correlated fading channels. These channels are characterized by high speed wireless interaction which typically fit in Intelligent Transportation System (ITS) mobility models. Simulations show that the performance of the system is degraded in a manner proportional to the vehicle’s velocity and channel correlation. It also demonstrates that Rician channels are less affected by higher mobility than Rayleigh channels.
Keywords- ITS Communication; MIMO; OSTBC; TCM; Rayleigh Channel; Rician Channel; Doppler Frequency, Correlation.