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Congestion in mobile ad hoc networks not only results in transmission delay and packet loss, but also degrades throughput. For effective congestion detection and control, accurate estimation of MAC overhead, packet retransmission, backoff interval and queuing delay is necessary. This paper proposes a congestion aware nodes (CAN) based scheme to control congestion in mobile ad hoc networks. In this...
Mobile ad hoc network is wireless network of mobile nodes, with no centralized management and control. We proposed a protocol with an enhanced route discovery mechanism that avoids the congestion in the route. Our proposed protocol selects route on the basis of traffic load on the node and resets path as the topology changes. Instead of transmitting entire data through one route, new efficient paths...
The performance of traditional TCP congestion control protocol degrades when congestion and contention increase in ad hoc networks that use the IEEE 802.11 DCF. Many of the problems result from medium contention at the media access control (MAC) layer. In this paper, we present a new contention-based congestion control (CBCC) method according to a novel congestion information from MAC layer. This...
The IEEE 802.16e standard has emerged as an exciting mobile wireless broadband technology that promises to deliver both high throughput and guaranteed quality of service (QoS). Call admission control (CAC) scheme serves as a great utility for WiMAX, which ensures that resources are not over committed and thereby, all existing connections enjoy guaranteed quality of service. Existing CAC schemes largely...
Resource reservation is one of the effective solutions in guaranteeing the quality-of-service (QoS) in communication networks. In this paper, we propose a novel resource reservation scheme for dynamically managing the bandwidth resources in IEEE 802.11e-based wireless local area networks (WLANs). The proposed solution consists of two components namely (i) dynamic medium access control (MAC) scheduler...
Admission control (AC) is an important feature in a wireless network by which radio resource usage is optimized whilst maintaining the Quality of Service (QoS) of existing users. In this paper, a novel admission control mechanism is proposed for the Long-Term Evolution (LTE) cellular networks. Simulation results show that the proposed AC can provide a more flexible trade-off between network and user...
In new generation cellular networks, opportunistic schedulers take advantage from the delay-tolerance of data applications to ensure that transmission occurs when radio channel conditions are most favourable. “Proportional Fair” (PF) is a well-known opportunistic scheduler that provides a good compromise between fairness and efficiency when transmitting long flows. Unfortunately, the PF algorithm...
A critical challenge for data transmission over wireless mesh networks (WMNs) is congestion control. In this paper, we explicitly describe a congestion control protocol for data transmission in WMNs, which supports high-speed data transmission and satisfies both the objectives of efficiency and fairness of flows without decreasing throughput of the networks. We demonstrate this protocol on our developed...
Vehicles in Intelligent Transportation System employ IEEE 802.11p/1609 protocols to communicate with other vehicles or roadside infrastructure within a specific area. Messages related with traffic safety can be delivered timely for collision avoidance and etc. Meanwhile, non-safety related infotainment messages can also be transmitted besides safety-critical information. Many of the safety critical...
Wireless video multicasting/broadcasting is an efficient method for simultaneous transmission of data to a group of users. But the multicasting rates are fixed in current IEEE 802.11 PHYs standard. In this paper, we propose a novel collision-detection based rate-adaptation scheme (CDRA), which fully exploits the potential of rate adaptation capability of wireless physical layer, to improve service...
Packet pacing in TCP has been introduced as one of the solutions to alleviate bursty traffic in TCP. In this paper, we investigate the performance of paced and standard (unpaced) TCP when coexist with DCCP over short and long delay link networks. We found that paced TCP for the entire TCP connection performs better in long delay link, with smoother throughput and better jitter, whereas in short delay...
Industrial networks based on IEEE 802.15.4 are spreading, even though the joint requirement on predictability and reliability from industrial applications is hard to fulfil in wireless networks, and the data rate of IEEE 802.15.4 is rather low. With the goal of providing real-time guarantees, with increased reliability and throughput, we propose two multichannel network architectures based on IEEE...
Network congestion in the heterogeneous Internet, which is connected by millions of asynchronous systems, poses a serious threat to communication and intermediate nodes that falls under its path. The primary cause of network congestion is that data in networks are overloaded and available resources are inadequate to contain such traffic loads. An enormous amount of proposed approach towards network...
There are two causes of network congestion: one is the lack of network resources, and the other is the irrational allocation of network resources. While traditional congestion control methods such as rate control, window mechanism, queue control, etc. can be applied to solve the congestion problem, but for the later congestion case, the fundamental solution is to make more effectively use of the network...
In wireless multi-hop Ad hoc networks, contending existing at MAC layer could easily results in congestion, and the first-in-first-out queue within the nodes could make the head of the queue blocked, which affects the transmitting of the following packets. In this paper, we present a variable packet size supporting and congestion-based opportunistic packet scheduling (VS-CBOS) algorithm, in which...
We propose a call admission control scheme for soft handoff of CDMA networks based on mobility estimation and mobility history of mobile stations. This work is further improvement of the Eliminating Pseudo Handoff Call (EPHC) proposed by Xiaomin Ma et.al. Therefore we named our proposed scheme as Improved EPHC (IEPHC). The proposed scheme not only improves network throughput but also reduces handoff...
In this paper, we consider the related issues of pre-emption and congestion control in Long Term Evolution (LTE) networks. A load-reduction method which can be used for either pre-emption or congestion control is described and evaluated by simulation. The simulation results show that the proposed mechanism can significantly improve dropping and blocking probabilities, depending on the bearer priorities.
The packet collision is one of the causes of wasted energy consumption in wireless sensor networks. This paper describes and analyzes the behavior of packet collisions in wireless sensor networks by simulations. The problems of packet collision include both direct and hidden collisions, and are classified by layers architecture: application, routing, and MAC. Moreover, we review and analyze the existing...
The long propagation delay, limited bandwidth and high bit error rate pose great challenges in Media Access Control (MAC) protocol design for underwater acoustic networks. In this paper, we proposed an underwater MAC protocol based on Carrier Sensing Multiple Access with Collision Avoidance (CSMA/CA), which is called UW-CSMA/CA (CSMA/CA for underwater). Three areas of improvement are investigated,...
Based on the analysis of TCP performance of over the two ways of IEEE 802.11 DCF (RTS/CTS and CSMA/CA), TCP flows becomes unstable when WLAN is in high load. In this paper, we propose a novel backoff algorithm for IEEE 802.11 DCF named as ACWB (adaptive contention window backoff) with cross-layer optimization. Its basic idea is to dynamically adjust the size of the contention window by the estimation...
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