IMPACT OF NUMBER OF CHANNELS ON THE CAPACITY OF SINGLE AND MULTI-CHANNEL WIRELESS NETWORKS

Abstract

Radio Frequency (RF) suffers lot of impairments and perturbations resulting in counters
such as call drops rate, failure rate and congestion rate on one hand and beam-width, fading,
shadowing and attenuation on the other hand. These factors seriously affect systems
capacity. To combat the effect of these impairments on the signal, the information can be
transmitted via multiple channels by deploying multiple antennas at both transmitter and
receiver. This antenna configuration is called Multiple-Input-Multiple-Output (MIMO). In
this paper, the performance of transmission over single channel was first investigated,
modelled and compared with that of multiple channels. Also, a mathematical model based
on Shannon capacity formula was used to obtain the capacity of different channels for fair
comparison. The results obtained shows that, the capacity from the coherent channel is 1.246
times higher than that of single channel. Also, that of non-coherent channel is 1.122 times
higher than that of single channel. Using the same index, orthogonal channel gives an
average capacity of n/2 higher than that of single antenna, this implies that, for a given
number of antennas say eight (n=8) at the same signal to noise ratio, the capacity of
orthogonal channel is about four (4) times higher than that of single channel. The results
indicate that the throughput and the reliability of the link improved more significantly when
the information is being sent over multiple uncorrelated channels. This can be achieved by
the use of orthogonal MIMO channels.