Mobile nodes are organized randomly without any access point in Mobile Ad hoc Networks (MANETs). Due to the mobility of nodes, the network congestion occurs. So many congestion control mechanisms were proposed to avoid the congestion avoidance or reducing the congestion status. In this research work, we proposed to develop the Effective Congestion Avoidance Scheme (ECAS), which consists of congestion monitoring, effective routing establishment and congestionless based routing. The overall congestion status is measured in congestion monitoring. In routing establishment, we propose the contention metric in the particular channel in terms of, queue length of packet, overall congestion standard, packet loss rate and packet dropping ratio to monitor the congestion status. Based on the congestion standard, the congestionless based routing is established to reduce the packet loss, high overhead, long delay in the network. By extensive simulation, the proposed scheme achieves better throughput, packet delivery ratio, low end-to-end delay and overhead than the existing schemes.
Satellite networking is different from wired or wireless networks. The behavior and the performance of TCP/IP in normal wireless network as well as in wired network are different from one another. The TCP/IP protocol was not designed to perform well over high-latency or noisy channels so its performance over satellite networks are totally different. Each satellite networks/constellations have different properties. The deployment height, motion, direction, link capacityall differ from one satellite constellations to another. So, certainly the behavior of TCP/IP will considerably differ from one satellite constellations than another. The Performance of three different TCP Congestion algorithms, Vegas, Reno and Bic are taken for evaluation on the simulated satellite network Iridium and the performance of the three algorithms under the satellites constellation is measured using suitable metrics. It is observed that, irrespective of the high end to end delay, the behavior of TCP/IP under Satellite network is somewhat resembling a high latency wired network. TCP under satellite network is not like that of a mobile ADHOC network. The observation resulted that the overall performance of Vegas was good in Iridium constellations. These reasons should be explored for designing a better congestion control algorithm exclusively for Satellite Networks.
Mobile Ad Hoc Networks consists of mobile nodes which are organized in a random manner. It can communicate with each other without any centralized infrastructure. Due to congestion, the packet loss is heavily occurred in the particular link. In order to avoid congestion, cross layer based congestion control scheme is proposed for reducing the packet losses in the network. The proposed scheme contains four phases. In first phase, the cross layer design is proposed to ensure that the information sharing can be done between the different layers in protocol stack. In second phase, the congestion detection scheme is explored which attains packet loss rate and congestion scale factor. In third phase, congestion control is achieved using cross layer approach. Here the congestion route is determined based on the path gain, buffer tenancy fraction. In fourth, new packet format is proposed. Each node maintains the congestion scale value, buffer tenancy fractional value. By extensive simulation, the proposed scheme achieves better throughput, congestion ratio, packet delivery ratio, low end to end delay and overhead than the existing schemes.
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