Research On Influence Of Wireless Channel Quality On Interference And Carrier Sense

Wireless channel’s space-time variant characteristics contain large scale and small scale fading, adjacent link’s interference on the same channel, etc. The effect of interference is also different under each bit rates. These uncertain factors make CSMA wireless network’s modeling very difficult in theory. Previous studies generally based on simplified wireless channel model, not ful y considered its uncertainty which is important. So we attempt to take wireless channel’s uncertainty into consideration to make model and carry out in-depth study of the future accurately.First of all, we studied several existing wireless network model, such as free space propagation model, two ray reflection model, and etc. Through dynamically adjusting parameters of path loss exponent, wireless transmission rate, interference distance, antenna’s height and system loss, from the angle of SNR, interference distance coefficient and average packet success, analyzed and verified the influence of the uncertainty factors of interference in MATLAB’s simulation; then considered cel ular model, analyzed and validated the influence of path loss exponents, frequency reuse factors and channel transmission rates on the capacity of the system. At last through NS-3 simulation experiments, studied the influence of Rayleigh fading model on average packet success rates and carrier sense under different wireless transmis s io n rates and interference distances, and then analyzed the reason of influences through the state of each node’s output.Through simulation, we verified the rationality of simplifying BER receiving model to SNRT receiving model, analyzed and verified that the SNR was only related to path loss model in theory, and path loss exponent has two sides in link’s SNR and the ability of anti-interference; under cel ular model, verified that wireless network achieves greater system capacity more easily in the city of built-up area than the rural of empty area. The influence of the Rayleigh fading channel is analyzed by the simulation of interference and carrier sense, finding the hidden and exposed termina l problems in the Rayleigh fading channel have a degree of ease. It has important theoretical significance and practical value in establishing wireless network model, evaluating wireless network performance and improving the carrier sense mechanism.