دانلود رایگان مقاله ارتباط چند به چند کمکی پیگی بکینگ در شبکه های ادهوک وسیله نقیله

ABSTRACT

Vehicular Ad-hoc NETworks (VANETs) have lately gained the interest of researchers due to their unique properties of high mobility and constantly changing network topology. As mentioned in IEEE 802.11p which is the standard for VANETs, CSMA is used as the channel access mechanism. However, CSMA causes high contention and leads to lower network performance in terms of packet delivery ratio and average end-to-end delay. Many-to-Many (M2M) communication is a technique which makes use of simultaneous transmission of packets by using Code Division Multiple Access (CDMA). Although M2M communication helps to improve the performance of VANETs, further improvements can be done to fully reap the benefits of M2M communication. In this paper, we suggest piggybacking of information along with M2M communication in a vehicular network scenario. This leads to dissemination of more information from a vehicle at a time, thereby increasing the average packet delivery ratio and average end-to-end delay. Our simulation results confirm that piggybacking along with M2M communication helps to improve network performance in terms of packet delivery ratio and end-to-end delay. We mathematically analyse average packet delivery ratio and average end-to-end delay of such a system by modelling the buffers at vehicles and RSUs as M/M/1 and M/D/1 queues, respectively. Our analytical results are verified by extensive simulations. In M2M communication, vehicles are chosen randomly to enter in a communication session. In this paper, we formulate an optimization problem for selection of vehicles which can enter in a communication session and also propose an efficient vehicle selection algorithm for the same. Our proposed algorithm not only improves the average packet delivery ratio and average end-to-end delay of the network but also significantly reduces the number of packets dropped in the network.

6. Conclusion and future work

In this paper, we have shown that many to many communication when aided by piggybacking of information in a VANET, gives better performance in terms of average packet delivery ratio and average end-to-end delay. This is because, piggybacking leads to dissemination of more messages from a vehicle at a time. We have analysed the average packet delivery ratio and average end-to-end delay of such a scenario by modelling the buffers at vehicles and RSUs as M/M/1 and M/D/1 queues, respectively. Our analytical results are validated by extensive simulations. We have formulated an optimization problem which depicts the way in which vehicles should be selected to enter in a communication session. To further enhance the performance, we have proposed an efficient vehicle selection algorithm which improves the average packet delivery ratio and average end-to-end delay. Additionally, our proposed algorithm also reduces the number of packets dropped. Future work in this direction includes developing a technique to assign codes to different vehicles in a distributed manner.