New adaptation method based on cross layer and TCP over protocols to improve QoS in mobile ad hoc network

Due to rapid growth of multimedia traffic used over the mobile ad-hoc networks (MANETs), to keep up with the progress of this constraints MANETs protocols becoming increasingly concerned with the quality of service. In view of the random mobility nodes in MANET, TCP becomes more unreliability in case of higher energy consumption and packet loss. In this paper we proposed a new optimization approach to enhance decision making of TCP based on some changes of IEEE 802.11 MAC uses cross layer approach. The aim is to minimize the impact of retransmissions of packet lost and energy consumption in order to analysed and chose the appropriate routing protocol for TCP that can be enhance QoS MANET. Our simulation results based QoS study using NS3 show that, our proposed achieves better performance of TCP in MANETs significantly, and also improved the throughput, energy consumption and facilitates the traffic transmission over routing protocol.

A Hybrid Link-TDMA MAC Protocol for Conventional and Radio over Fiber WLANs

During the last two decades, the IEEE 8201.11 family has multiplied data rate transmissions in wireless local area networks (WLANs). This progress is based on the adoption of new technologies concerning physical layer (PHY), combined with the enhancements in the medium access control (MAC) layer. Radio over Fiber (RoF) is a technology which can further extend this progress, combining the benefits of optical fiber and wireless networks. The current IEEE 802.11 MAC protocol is contention based, which leads to low utilization of the RoF PHY data rate and on the other hand cannot handle the effects of long propagation delays in RoF networks. In this paper, we present a new Hybrid Link Time Division Multiple Access (HL-TDMA) MAC protocol which addresses the above shortcomings and enhances the performance of both conventional and RoF WLANs. Then, through simulation, we evaluate the performance of the proposed protocol, which is shown to be superior to relevant RoF WLAN protocols in the literature.

An Insight of Backoff Algorithms in Wireless Networks

The IEEE 802.11 MAC is liable for the scheme of channel accessing. It decides the performance of the WLAN and DCF is the central strategy. Stations that need to get to the divert may partake in a disseminated manner by means of CSMA/CA in the MAC layer. Packet collision can’t be totally avoided because of the nodes which are in scattered manner. MAC layer uses a BEB scheme for CA (collision avoidance).. Nodes are experiencing a collision in common channel in IEEE 802.11 and must have to backoff for a arbitrary time and selected consistently from CW. The contention window is maintained dynamically by BO algorithms. Network performance is decreased due to a sudden change in window size. Different existing algorithms for backoff and comparision among the algorithms are shown in the manuscript.