An Adaptive Channel Model for VBLAST in Vehicular Networks |
The wireless transmission environment in vehicular ad-hoc systems varies from line of sight with a small number of surroundings to Rayleigh fading and rich scattering. An efficient communication system must be able to adapt itself to these diverse conditions. Multiple antenna systems are known to provide superior performance compared to single antenna system in terms of capacity and reliability. The correlation between the antennas has a great effect on the performance of MIMO systems. In this paper we introduce a novel adaptive channel model for MIMO-VBLAST systems in vehicular ad hoc networks. Using the proposed model, the correlation between the antennas was investigated. Although the line of sight is ideal for single antenna systems, it severely degrades the performance of VBLAST systems since it increases the correlation between the antennas. A channel update algorithm using single tap Kalman filters for VBLAST in flat fading channels has also been derived and evaluated. At 12dB Es/N0, the new algorithm showed 50% reduction in the mean square error (MSE) between the actual channel and the corresponding updated estimate compared to the MSE without update. The bit error rate using the proposed channel update algorithm was approximately 10-3 compared to 10-1 without the update at 20dB Es/N0 and vehicle speed of 60kph. The computational requirement of the proposed algorithm for a p´q VBLAST is 6p´q real multiplications and 4p´q real additions.
Abdalla GMT, Abu-Rgheff MA, Senouci S-M