Tham khảo tài liệu 'mobile ad hoc networks applications part 14', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 446 Mobile Ad-Hoc Networks Applications a DSDV b DSR d AOMDV c AODV Number of TCP connections e OLSR Fig. 11. Throughput measurement in the random topology The Effect of Packet Losses and Delay on TCP Traffic over Wireless Ad Hoc Networks 447 Throughput measurement The TCP variants over DSDV achieve a higher throughput by a factor of almost on average compared to others as shown in Fig. 11 a . The better stability of throughput for the TCP variants could be encountered in proactive routing protocols DSDV and OLSR Fig. 11 e . When the number of nodes increases the possibility of congestion and the contention at the MAC layer increase in the network. However when the routing layer protocols receive the collision reports from the link layer they re-discover routes by sending the broadcast messages throughout the network. Therefore in Fig. 11 c AODV suffers a lower throughput if compared to others. Another thing is that DSR suffers the instability throughput for all TCP variants because when the node density and the number of connections increase the stale route problem of DSR comes active and makes the performance worse Fig. 11 b . 6. Conclusion In this chapter we analyze the performance of TCP variants across ad hoc routing protocols in static and mobile ad hoc environments. The performance of TCP variants vary depending on the routing protocols their core mechanisms and background changes such as the node mobility node speed pause time and number of tcp connections and network topologies. In the chain topology all of the TCP variants achieve a significantly lower delay over AODV routing protocol in both environments. Moreover AODV provides a higher throughput for all TCP variants especially for Vegas in both environments. One interesting thing is that AODV always achieves a lower delay it suffers a higher delay than others in the grid topology. In the grid topology although TCP variants have the lowest delay over DSDV in both environments in the random .
