Congestion Control In Wireless Networks Research Articles

Enhanced Congestion Control in Wireless Networks: A Joint Random Early Detection and Drop Tail Mechanism

Enhanced Congestion Control in Wireless Networks: A Joint Random Early Detection and Drop Tail Mechanism

The Performance Evaluation of Adaptive Guard Channel Scheme in Wireless Network

Dynamic Guard Channels (DCG) reduces the dropping and blocking rates in a network. However, most of the existing DGC allocations are not quite efficient because there were consideration for only the Handoff (HO) calls while the New calls (NC) were not considered; this leads to poor Quality of Service (QoS) for NC. Although it is better to give priority to HO calls over NC since the breaking of the connection of an established communicationis more annoying than blocking a NC. Thus, there is need to provide an alternative approach that guarantees an acceptable QoS in terms of both the HC and the NC. This paper presents the performance evaluation of an adaptive guard channel allocation; the scheme made use of two different models (1) guard channel with fuzzy logic (2) guard channel without fuzzy logic. Priority is given to handoff call due to the scarcity of radio spectrum. When all the guard channels have been allocated and the arrival rate of handoff calls keeps on increasing, new set of threshold values would be estimated by fuzzy logic model. Performance metrics are; Call Blocking Rate (CBR), Call Dropping Rate (CDR) and Throughput. Results showed that guard channel with fuzzy logic has the CBR values range from 24.02% to 69.015 and CDR values range from 12.025 to 18.90% while guard channel without fuzzy logic has CBR values range from 28.22% to 75.65% and CDR values range from 19.06% to 36.50%. The scheme proved to be more efficient in congestion control in wireless network.

TCP CERL+: revisiting TCP congestion control in wireless networks with random loss

In this paper, we analyze the performance of wireless networks subject to random loss. In this regard, we revisit our TCP Congestion Control Enhancement for Random Loss (CERL) mechanism that has been introduced earlier in a previous study. We call our new developed TCP variant as CERL Plus (CERL+). TCP CERL+ is a modification of TCP Reno at sender-side. TCP CERL+ is a new generation that works similarly as TCP CERL but its main idea is to use a dynamic threshold in terms of RTT. In doing this, we employ the average RTT and its minimum measurements made over the connection to estimate the queue length of the bottleneck link. As a result, we can use this queue length to evaluate the congestion status and distinguish it from the random loss status. This in turn would not reduce the window size leading to enhance the performance of the proposed algorithm in the sense of increasing the amount of data transmission. Additionally, CERL+ alleviates the congestion in the bottleneck obviously. In this paper, we present simulation experiment for TCP CERL+ considering a two-way transmission assuming a heavy load and wide range of random loss rates compared to TCP NewReno, TCP New Jersey + , TCP mVeno, TCP Westwood + , TCP Cubic and TCP YeAh using the network simulation ns-2. Simulation results prove that CERL+ outperforms other TCP variants and achieves excellent throughput gain.

IF-RD optimisation for bandwidth compression in video HEVC and congestion control in wireless networks using dolphin echolocation optimisation with FEC

At present, the latest standard for coding the videos is high-efficiency video coding (HEVC) technique. Owing to limitations of wireless channels on time variability and bandwidth, video transmission to multiple mobile users is difficult. Inter frame-rate distortion (IF-RD) is the technique used in this paper, and it provides more clear videos with a reduction in motion signal by compressing bandwidth and enhancing optimisation in HEVC. First, the multi-resolution encoder encodes the video by employing a fusion strategy called IF-RD optimisation strategy. In order to improve performance and achieve noiseless transmission, the forward error correction (FEC) and dolphin echolocation optimisation techniques are integrated. Token-based congestion control (TBCC) reduces messages that are dropped due to congestion in the network. It also provides computation time. By adopting HEVC, the system performs well and achieves better compression in bandwidth and saves better Peak signal-to-noise ratio (PSNR) data rate with no extra time for encoding.

IF-RD optimisation for bandwidth compression in video HEVC and congestion control in wireless networks using dolphin echolocation optimisation with FEC

IF-RD optimisation for bandwidth compression in video HEVC and congestion control in wireless networks using dolphin echolocation optimisation with FEC

Network Utility Maximization-Based Congestion Control Over Wireless Networks: A Survey and Potential Directives

Since the initial publication of Kelly et al.'s seminal paper on resource allocation in wired networks, a large number of studies based on the network utility maximization (NUM) framework have been conducted, for example, on resource allocations in wired networks as well as wireless networks. Congestion control, used to adapt the traffic rates injected into a network, can be controlled separately at the transport layer or mutually with other layers, using a cross-layer design. The focus of this paper is a review of the research following the NUM framework and addressing the problem of congestion control from several dimensions, specifically, elastic traffic or inelastic traffic, same-timescale or multi-timescale, and single-path or multipath transmissions. First, cross-layer designs for wireless networks, basics of optimization theory, and an example of cross-layer congestion control are summarized. Then, studies on NUM-based congestion control are sequentially presented from several points of view. In addition, we survey the recent literature on cross-layer resource allocation in next generation networks, software-defined networking, and cloud radio access networks, which can enhance the performances and address issues found in current networks. Finally, we outline what we consider to be the current challenges and open issues in the area of NUM-based congestion control for wireless networks.

Performance of TCP Congestion Control in UAV Networks of Various Radio Propagation Models

Unmanned aerial vehicles (UAVs) have recently become popular for both recreational and commercial use and UAV networks have thus started to attract the attention of researchers in area of the computer communication and networking. One important topic in UAV networks is congestion control because congestion causes packet losses and delays which result in the waste of all types of network resources such as bandwidth and power. Although there are studies on the performance of TCP congestion control in wireless networks, they focus on terrestrial networks of two dimensions in general. In this paper we study the performance of TCP congestion control in three dimensional UAV networks. In particular, we investigate how TCP congestion control performs in such type of network using various radio propagation models. Our data on the average flow throughput, packet delay, and packet loss rate in UAV networks show that TCP congestion control improves the network performance of UAV networks in general, but it faces challenges when the link losses become severe. Our study thus shows that investigation on new congestion control schemes is stilled needed for the emerging UAV networks.

TCP-AP Enhanced Behaviour With rt-Winf And Node Count: boosted-TCP-AP

<p>Congestion control in wireless networks is strongly dependent on the dynamics and instability of wireless links. Therefore, it is very difficult to accurately evaluate the characteristics of the wireless links. It is known that TCP experiences serious performance degradation problems in wireless networks. New congestion control mechanisms, such as TCP-AP, do not evaluate accurately the capacity and available link bandwidth in wireless networks. In this paper we propose new congestion control protocol for wireless networks, based in TCP-AP. We name the protocol boosted-TCP-AP. It relies on the MAC layer information gathered by a new method to accurately estimate the available bandwidth and the path capacity over a wireless network path (rt-Winf), and also takes into consideration the node path count. The new congestion control mechanism is evaluated in different scenarios in wireless mesh and ad-hoc networks, and compared against several new approaches for wireless congestion control. It is shown that boosted-TCP-AP outperforms the base TCP-AP, showing its stable behavior and better channel utilization.</p>

XCP-Winf and RCP-Winf: Improving Explicit Wireless Congestion Control

Congestion control in wireless networks is strongly dependent on the dynamics and instability of wireless links. Therefore, it is very difficult to accurately evaluate the characteristics of the wireless links. It is known that TCP experiences serious performance degradation problems in wireless networks. Moreover, congestion control mechanisms that rely on network interaction and network parameters, such as XCP and RCP, do not evaluate accurately the capacity and available link bandwidth in wireless networks. In this paper we propose new explicit flow control protocols for wireless mesh networks, based on XCP and RCP. We name these protocols XCP-Winf and RCP-Winf. They rely on the MAC layer information gathered by a new method to accurately estimate the available bandwidth and the path capacity over a wireless network path. The estimation is performed in real time and without the need to intrusively inject packets in the network. These new congestion control mechanisms are evaluated in different scenarios in wireless mesh and ad hoc networks and compared against several new approaches for wireless congestion control. It is shown that both XCP-Winf and RCP-Winf outperform the evaluated approaches, showing its stable behavior and better channel utilization.

Congestion Control Technique for Wireless Networks

Congestion control in wireless networks has been extensively investigated over the years and several schemes and techniques have been developed, all with the aim of improving performance in wireless net-work. With the rapid expansion and implementation of wireless technology it is essential that the congestion control problem be solved. This paper presents a congestion control schemes which are different in slow start threshold calculation, bandwidth estimation, and congestion window manipulation. A comprehensive comparison of these approaches is given in relation to assumptions, bandwidth estimation, congestion window size manipulation, performance evaluation, fairness and friendliness and improved throughput. I. Introduction The congestion control in wireless networks has been extensively investigated over the years and several schemes and techniques have been developed, all with the aim of improving performance in wireless network. With the rapid expansion and implementation of wireless technology it is essential that the congestion control problem be solved. The Transmission Control Protocol (TCP) has been widely used in today's Internet. The protocol supports reliable data transport by establishing a connection between the transmitting and receiving ends. The transmitter starts a timeout mechanism when sending a packet to the receiver. The transmitter constantly tracks the round-trip times (RTTs) for its packets as a means to determine the appropriate timeout period. At the receiver, each received packet is acknowledged implicitly or explicitly to the transmitter. If the transmitter does not receive an acknowledgment for a given packet when the corresponding timeout period expires, the packet is deemed to be lost and subject to retransmission. A congestion window with dynamically adjusted size is used by the protocol to regulate the traffic flow from the transmitter to the receiver. Although TCP was initially designed and optimized for wired networks, the growing popularity of wireless data applications has lead third generation wireless networks such as CDMA2000 and UMTS networks to extend TCP to wireless communications as well. The initial objective of TCP was to efficiently use the available bandwidth in the network and to avoid overloading the network (and the resulting packet losses) by appropriately throttling the senders' transmission rates. Network congestion is deemed to be the underlying reason for packet losses. Consequently, TCP performance is often unsatisfactory when used in wireless networks and requires various improvement techniques. A key factor causing the unsatisfactory performance is that the radio link quality in wireless networks can fluctuate greatly in time due to channel fading and user mobility 1.1 Problems of TCP in Wireless Scenario TCP protocol may experience performance degradations over wireless networks, due to non-congestion related packet loss and varying round trip times Unmodified standard TCP performs poorly in a wireless environment due to its inability to distinguish packet losses caused by network congestion from those attributed to transmission errors. Packet loss or reception of out of- order packets indicates failures. To remove such failures ,TCP implements flow control and congestion control algorithms based on the sliding window. The performance of TCP is generally lower in wireless networks than in fixed .Thesis explained by the fact that TCP cannot distinguish problems that typically occur in wireless networks from congestion. The congestion control algorithms in TCP are based on the assumptions that data is lost mainly due to congestion and that data loss duet transmission errors is rare .Therefore, data loss is interpreted as a signal of congestion in the network. Even in a wireless network, where data loss may not be related to congestion, TCP considers it as a congestion case.TCP segments may be lost if the radio conditions are poor and the link layer protocol provides a low reliability. After some retransmission attempts the link layer protocol gives up and leaves further error recovery to TCP. Handover events may also lead to data loss. A whole window of data may be lost due to handover. Data loss due to an unreliable link layer or a handover may cause a timeout event followed by slow start or three Daypack followed by fast retransmit and fast recovery. In either case, the congestion control action taken by TCP is unnecessary. Directly after the loss event ,the radio quality may become high again, and after handover data may be transmitted without problems to the new base station.TCP may also misinterpret a sudden increase in the round trip time as data loss. If the delay is long enough for the retransmission timer to expire before an acknowledgments received, then TCP misinterprets the delay as an indication of data loss due to congestion.

A Novel Congestion Control Mechanism with Accelerating Effect

tremendous growth of wireless network demands the need to meet different multimedia applications available over the wireless networks. Network congestion occurs when a link or a node is carrying an excessive amount of data because of which the quality or service deteriorates and these demands and allocations lead to optimized rate based control regulation through queuing theory. Earlier works on rate control protocols does not emphasize on different RCP wireless practical situations which may have varying or constant link and packet acceptance capacity, bandwidth coordination, acceleration maintenance etc. In this paper, we purpose a novel, methodology for rate based congestion control in wireless network. Thus, we proposed an algorithm of a range based capacity wireless network with different conditions for maintaining the acceleration and traffic in terms of capacity of processor nodes and link capacity

Stability and Hopf Bifurcation of a Fluid-Flow Model for Congestion Control in Wireless Networks

Stability and Hopf Bifurcation of a Fluid-Flow Model for Congestion Control in Wireless Networks

On Approaches to Congestion Control over Wireless Networks

Congestion control in wireless networks has been extensively investigated over the years and several schemes and techniques have been developed, all with the aim of improving performance in wireless net-work. With the rapid expansion and implementation of wireless technology it is essential that the congestion control problem be solved. This paper presents a survey of five congestion control schemes which are dif-ferent in slow start threshold calculation, bandwidth estimation, and congestion window manipulation. A comprehensive comparison of these approaches is given in relation to assumptions, bandwidth estimation, congestion window size manipulation, performance evaluation, fairness and friendliness and improved throughput.

Node-Based Optimal Power Control, Routing, and Congestion Control in Wireless Networks

In wireless networks, important network functionalities such as power control, rate allocation, routing, and congestion control must be optimized in a coherent and integrated manner. In this work, an interference-limited wireless network is considered, whereby power control and routing variables are chosen to minimize the sum of link costs which depend on both link capacities and link flow rates. The necessary conditions for optimality are established. These conditions are sufficient for optimality if link cost functions are jointly convex, and imply Pareto optimality if link costs are strictly quasi-convex. Network algorithms based on the scaled gradient projection method, where power control and routing are performed on a node-by-node basis, are presented. For these algorithms, explicit scaling matrices and stepsizes are found which lead to more distributed implementation, and which guarantee fast convergence to a network configuration satisfying the optimality conditions, starting from any initial configuration with finite cost. Refinements of the algorithms for more accurate link capacity models are presented, and the results are extended to wireless networks where the physical-layer rate region is given by an arbitrary convex set. Finally, it is shown that the power control and routing algorithms can naturally be extended to incorporate congestion control.

Enhancements on Router-Assisted Congestion Control for Wireless Networks

This paper addresses two challenges that are encountered when applying router-assisted explicit-feedback congestion control to wireless networks. The first challenge is how to distinguish between the two kinds of packet loss (non- congestion loss and congestion loss) in wireless networks and how to react to them properly. The second challenge is how to probe the unknown bandwidth capacity of wireless links which is required in calculating the router feedback. Some practical and novel enhancements on router-assisted congestion control in such environments are introduced in this paper. We have implemented these enhancements in a router-assisted congestion control protocol termed QFCP. Extensive simulation experiments using ns-2 will demonstrate that QFCP can fairly and efficiently allocate wireless bandwidth resources among competing flows in heterogeneous networks.

The impact of imperfect scheduling on cross-layer congestion control in wireless networks

In this paper, we study cross-layer design for congestion control in multihop wireless networks. In previous work, we have developed an optimal cross-layer congestion control scheme that jointly co...

The impact of imperfect scheduling on cross-layer congestion control in wireless networks

In this paper, we study cross-layer design for congestion control in multihop wireless networks. In previous work, we have developed an optimal cross-layer congestion control scheme that jointly computes both the rate allocation and the stabilizing schedule that controls the resources at the underlying layers. However, the scheduling component in this optimal cross-layer congestion control scheme has to solve a complex global optimization problem at each time, and is hence too computationally expensive for online implementation. In this paper, we study how the performance of cross-layer congestion control will be impacted if the network can only use an imperfect (and potentially distributed) scheduling component that is easier to implement. We study both the case when the number of users in the system is fixed and the case with dynamic arrivals and departures of the users, and we establish performance bounds of cross-layer congestion control with imperfect scheduling. Compared with a layered approach that does not design congestion control and scheduling together, our cross-layer approach has provably better performance bounds, and substantially outperforms the layered approach. The insights drawn from our analyzes also enable us to design a fully distributed cross-layer congestion control and scheduling algorithm for a restrictive interference model.

The impact of imperfect scheduling on cross-Layer congestion control in wireless networks

The impact of imperfect scheduling on cross-Layer congestion control in wireless networks