Abstract
Active safety broadcast is one of the most fundamental services in intelligent transportation systems. The repetition code proposed in wireless access for vehicular environment (WAVE) standard is inefficient in realistic channel conditions and rapidly changing network topologies. In this study, we propose the use of systematic raptor codes as a forward error correction (FEC) scheme at the MAC layer. This code is optimised for short packet lengths, as are expected in safety applications. We have developed a multi-layered simulator that consists of realistic IEEE 802.11p physical layer results, an analytical random access MAC model and FEC codes implemented at different OSI layers. The model considers safety messages under non-saturated channel conditions according to the vehicular IEEE 802.11p standard. Issues such as the hidden nodes problem, interference and vehicles leaving the communication area are considered. The performance evaluation of raptor codes against repetition codes in the shared control channel with different antenna schemes is also presented.
Highlights
In Europe, more than one million road traffic accidents occur each year, resulting in around 40,000 fatalities, 1.6 million non-fatal injuries and €160 billion in economic loss [1]
Our contribution to improve the accuracy of this model is by integrating our packet error rate (PER) curves from the PHY layer simulator results in Section “Detailed physical layer system model”
To determine the average end-to-end automatic collision notification (ACN) warning delay, we find the minimum values of Nr and ESIK+ε for different channel erasure rates at different d distances and β densities by using a Monte Carlo simulation approach
Summary
In Europe, more than one million road traffic accidents occur each year, resulting in around 40,000 fatalities, 1.6 million non-fatal injuries and €160 billion in economic loss [1]. It will be shown that the adoption of raptor codes at MAC layer offers significant savings to the average end-to-end delay and packet reception rate as compared to implementation at the application layer (as proposed in the standard [7] and recent works [20]) This is due to less overhead requirement and improved packet error performance. Our proposed approach of raptor codes implementation at the MAC layer offers the best delay and packet reception rate performance This is due to the best PER curve (72B) observed, as well as the reduction in overhead and channel sensing requirement. These results are not included in this article due to space limitation
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