Modelling of Bit Error Rate as a Function of Knife Edge Diffraction Loss Based on Line of Sight Percentage Clearance

Abstract

In this paper, modelling of bit error rate as function of knife edge diffraction loss based on line of sight (LoS) percentage clearance is presented. Mathematical expressions for investigating the effect of variations in percentage clearance (Cp %) of 1st Fresnel zone on diffraction loss, bit energy per noise-density (E_b/N_0) in dB and bit error rate (BER) are presented. Also, the average error bits per second for binary phase shift keying (BPSK), pulse amplitude modulation (PAM) and 4-quadrature amplitude modulation (4-QAM) digital modulations in additive white-Gaussian-noise (AWGN) are specified. Simulated result is shown to analyse and compare the bit error rate as a function of diffraction loss for the selected digital modulation schemes. The results show that the reduction in percentage clearance for first Fresnel zone reduces the energy per noise-density thereby increasing bit error rate. MAT LAB results show that the average error bit per second of BPSK has 0.0000, PAM has 0.1429, and 4-QAM has 0.0009. In all, for any given percentage clearance, BPSK has the smallest number of error bits per second. Also, the lowest BER and the lowest number of error bits per second occur at about 70 % clearance of 1st Fresnel zone. For any given amount of reduction in Cp%, the corresponding increase in BER and number of error bits per second increases as data rate increases.