Effect of Waiting Time and Number of Slots on Vehicular Networking Employing Slotted ALOHA Protocol

Abstract

This work investigates through simulation effect of waiting time and number of slots on the effectiveness of using Slotted ALOHA in vehicular connectivity as a random access technique. The objective is to reach optimum level of throughput under the vehicular dynamic environment. The presented work proposes to concentrate on waiting time as a controlling parameter that can be used in an adaptive manner to enable throughput optimization in response to changing vehicular density. The work proved through MATLAB simulation the importance of waiting time parameter in controlling number of delivered frames and throughput. The results show that based on the exponential relationship between throughput and data traffic, there is a logarithmic relationship between data traffic and waiting time, which complements another logarithmic relationship between throughput and waiting time. The simulation also shows that there is an inverse relationship between throughput and data traffic as a function of set waiting time. The simulation shows that there is an exponential relationship between waiting time and maximum number of delivered frames. The work shows that a linear region of operating Slotted ALOHA can be specified, such that an optimum and dynamically adjusted waiting time is set with overall effect on number of slots and throughput. The dynamic shape function of the curve correlating waiting time to available number of slots is mathematically modelled and differentially controlled, thus an optimizing and controlling algorithm is produced, which improves significantly the conventional ALOHA performance and has an advantage over other used ALOHA derivatives, in that it concentrates on available slots and waiting time, which greatly contributes towards reduction in collisions and improving of throughput.