Combined preventive/reactive congestion control in LAN/MAN interconnection networks

In this paper, we study the performance of utility maximization congestion control over multihop CSMA-based networks. We consider decoupled vs. joint design of congestion control and medium access and consider unmodified MAC protocols such as IEEE 802.11. Networks employing such MAC protocols incur flow starvation both without congestion control and with existing TCP-based congestion control. We develop a framework to study key issues in such networks that are not incorporated by prior models, yet are critical to the performance of congestion control algorithms. We study the role of data transmission capacity that is location dependent and, even more, unknown. We show that for the case of consistent channel state, a single globally optimal data transmission capacity does not exist. Moreover, for the case of inconsistent channel state that arises due to the carrier sense mechanism itself, a data transmission capacity that provides convergence to perfectly fair rates does not exist, i.e., the congestion control algorithm converges to incorrect rates. We study the impact of inter-node collaboration within a contention region, and show that collaboration can alleviate these problems and ensure convergence to fair rates. Finally, we compare the performance of congestion control in a collaborative network with the performance of TCP, and show that TCP starves some flows, whereas congestion control with collaboration removes starvation, provides significantly better fairness, and achieves 17% higher aggregate throughput.

The main essence of this proposed method for the control of congestion in VANET is exploiting the already existing resources of the network and at the same time preventing the unnecessary overheads of nodes as well as links of a network. The control of congestion in the networks such as vehicular ad hoc suffers through a special kind of challenges. These challenges are the consequences of the environmental specificities such as frequently changing of the topology, large amount of variations in the nodes density, nature of the communication in broadcasting and the configurational characteristics of the neighbor etc. Keeping above described point into mind, we proposed a technique for the control of unnecessary congestion by reducing the number of transmitting messages in VANET. It supports discarding of similar types of messages. Here each node consists of a neighbor table for comparing the incoming messages with the previous messages. The information from the message is extracted and the values are compared with the values of neighbor table using a database query. If a match is found then the corresponding message field in the table is updated else a new entry is added in the table and the message is transferred to control queue (CQ) or the service queue (SQ).After being processed the entry is deleted from the queue as well as table. The working efficiency of this developed method is determined on the ground of the average delay of these three main types of messages v/s its mean message size.

The purpose of this study is to propose a new congestion control framework for uni-priority of event-driven safety messages in VANETs. The uni-priority congestion is caused by the traffic of the same priority. Many of event-driven safety applications developed for VANETs is required real-time communication with high reliability and must be delivered before certain time deadline. In high load traffic, the CCH communication channel easily congested. Many studies [2,10,11,12] recommended congestion control approach to control the load and congestion on the wireless channel in VANETs. Our proposed congestion control will reserve the CCH communication channel for event-driven safety messages if the number of safety messages in the queue exceeds a defined threshold or the congestion control detect event-driven safety message. In normal traffic, the CCH communication channel is not reserve for event-driven safety messages. This research will adapt priority-based Earliest Deadline First (EDF) scheduling algorithms in proposed congestion control to schedule uni-priority of eventdriven safety messages. In addition, to provide reliability performance for event-driven safety messages, we will develop a new rebroadcasting scheme to prevent broadcast storm. In next phase of study, we plan to test and evaluate performance of our congestion control approach using network simulator e.g. NS-3.

Unlike TCP/IP networks, in DTNs end-to-end paths between nodes cannot be guaranteed at all times. This means that DTN nodes may have to store messages for long periods of time before they can forward the messages towards their ultimate destinations. As a result, congestion control in DTNs is critical to achieve adequate performance, yet needs to be fundamentally different from congestion control in TCP/IP networks. This paper presents a comprehensive comparative performance study of DTN congestion control in a wide range of DTN scenarios. It complements our previous work~\cite{katia} in which we study the performance of DTN congestion control in interplanetary network scenarios. As in~\cite{katia}, our results confirm that although congestion control helps alleviate DTN congestion, existing mechanisms fall short from achieving adequate message delivery ratio and latency. Our study also confirms that congestion control in DTN scenarios should be independent of the underlying routing protocol, should employ a combination of reactive and proactive control as well as local information instead of relying on global knowledge.

The main objective of congestion control is to best exploit the available network resources while preventing sustained overloads of network nodes and links. Appropriate congestion control mechanisms are essential to provide effcient operation of a network. Ensuring congestion control within vehicular ad hoc networks faces special challenges, due to the specificities of such environment (High mobility of nodes, high rate of topology changes, high variability in nodes density and neighborhood configuration, broadcast/geocast communication nature, etc.). In this context, we present in this paper a cooperative and fully distributed congestion control approach, based on dynamic scheduling and transmission of priority-based messages, to ensure reliable and safe communication architecture within VANET. Messages priorities are dynamically evaluated according to their types, the network context, and the neighboring nodes configuration. Considering the context of high reliability and real-time response required for intervehicular communications (including emergency breaking notification for example), we propose a complete validation method of our congestion control algorithms, taking into account reliability, temporal, and operational aspects.

Asynchronous Transfer Mode (ATM) has been chosen as the multiplexing technique for Broadband Integrated Services Digital Networks. Under ATM, all information types (voice, data, image and video) are represented in terms of standardized units called cells. The acceptance of the ATM cell by the computer and communications industry as standard unit of information exchange will have a significant impact on the future development of communications infrastructure and end-user equipment. In this paper, we consider the performance modeling and evaluation of ATM-based networks. The performance issues at the ATM Layer and the ATM Adaptation Layer (AAL) are discussed. These include traffic characterization, multiplexing and switching, quality of service classes, call acceptance, congestion control, and AAL performance. Performance results on multiplexing and switching, and LAN interconnection using an ATM switch, are presented.

Congestion in Wireless Multimedia Sensor Networks (WMSN) may cause packet loss, buffer overflow and increases queueing delay, which has a significant negative impact on the network performance and reliability. This problem imposes more resource constraints that involve energy consumption and buffer size to meet additional requirements such as desired buffer size and limited amount of packet loss. One of the fundamental issues of congestion problem in such networks is the queue management. In fact, handling congestion without considering flexible buffer management and queueing methods, stay insignificant against dropping rate and packet loss. Consequently, a novel congestion control approach is needed to overcome these problems. In this paper, a new queue management mechanism called: Priority Queue Management based Explicit Congestion Control (PQMECC) is proposed and modeled using Stochastic Automata Networks, which are appropriate for modeling and analyzing complex systems with interacting components and complex synchronization. The congestion control technique used in PQMECC is based on priority, load repartition mechanism and explicit congestion notification which is generated only if the congestion reaches the threshold value.

In deep space missions, large-scale deep space information and continuous sensory data are generated, processed, and exchanged over Internet of deep space things (IoDST). Ensuring reliable communication in IoDST requires resolution of challenges engendered by the unique characteristics of IoDST, including long propagation delays, link outages, high error rates, and asymmetric bandwidths. Thus, transmission control protocol (TCP) layer functionalities are crucial for ensuring reliable IoDST communications. However, existing TCP congestion control (CC) protocols present poor performance in IoDST communications, owing to the dependence of traditional window-based CC approaches on pre-configured rules to adjust transmission rate against the aforementioned unique characteristics. In this paper, we propose an intelligent CC scheme called optimistic actor–critic-based TCP congestion control (OAC-TCPCC) to solve the problems of the challenging link conditions in IoDST. OAC-TCPCC dynamically determines optimal congestion window for data transmission over IoDST communication links to maximize the TCP throughput performance and minimize file transfer time. Simulation results reveal that OAC-TCPCC improves the TCP throughput performance by up to 27%, 79%, 92%, 477%, 643%, and 766%; and reduces file transfer time by up to 16%, 37%, 50%, 48%, 58%, and 79%, compared to DRL-CC, TP-Planet, FAST TCP, TCP Peach, TCP BBR, and TCP CUBIC, respectively.

Several congestion control methods for asynchronous transfer mode (ATM,) networks that support multimedia traffic by providing different guaranteed quality for each class of traffic are discussed. The two categories of congestion control methods presented are preventive congestive control and reactive congestive control. Preventive congestion control takes any action necessary to prevent congestion Reactive congestion control is responsible for any necessary action to recover from a congested situation, A summary of a proposed multilevel control scheme is also presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Throughput and fairness performance of transmission control protocol (TCP) worsens critically under vehicular environment due to its weakly bounded congestion threshold parameter, rate reduction approach and congestion recovery algorithm. In this paper, a new congestion control algorithm for vehicular networks, called VC-TCP (Vehicular customized -TCP) is proposed to overcome the limitations of the existing independent congestion control approaches. The VC-TCP implements a newer congestion threshold parameter, which regulates the spurious rate reduction due to an abrupt increase in RTT spike value. During the congestion control process, VC-TCP uses a new recovery algorithm and bandwidth utilization based rate reduction, which substantially improves the flow fairness of TCP traffic flows with different bandwidth utilization levels. The throughput, flow fairness, and packet latency performances of VC-TCP is evaluated against the standard Vegas congestion control approach under simulated vehicular scenarios. The simulation outcomes verify the performance improvement of the proposed VC-TCP approach against the standard TCP variants in the different facets of the vehicular environment.

Channel congestion is one of the major challenges for IEEE 802.11p-based vehicular networks. Unless controlled, congestion increases with vehicle density, leading to high packet loss and degraded safety application performance. We study two classes of congestion control algorithms, i.e., reactive state-based and linear adaptive. In this paper, the reactive state-based approach is represented by the decentralized congestion control framework defined in the European Telecommunications Standards Institute. The linear adaptive approach is represented by the LInear MEssage Rate Integrated Control (LIMERIC) algorithm. Both approaches control safety message transmissions as a function of channel load [i.e., channel busy percentage (CBP)]. A reactive state-based approach uses CBP directly, defining an appropriate transmission behavior for each CBP value, e.g., via a table lookup. By contrast, a linear adaptive approach identifies the transmission behavior that drives CBP toward a target channel load. Little is known about the relative performance of these approaches and any existing comparison is limited by incomplete implementations or stability anomalies. To address this, this paper makes three main contributions. First, we study and compare the two aforementioned approaches in terms of channel stability and show that the reactive state-based approach can be subject to major oscillation. Second, we identify the root causes and introduce stable reactive algorithms. Finally, we compare the performance of the stable reactive approach with the linear adaptive approach and the legacy IEEE 802.11p. It is shown that the linear adaptive approach still achieves a higher message throughput for any given vehicle density for the defined performance metrics.

Congestion causes packet loss which in turn drastically decreases network performance and throughput. As sensors are energy constraint so it is a decisive task to detect congestion and perform congestion control. Additionally, varieties of application have different requirement (i.e. delay, link utilization, and packet loss). In this paper we proposed an application priority based rate control algorithm to mitigate congestion in sensor network. This approach also maintains an interactive queue management scheme so that requirements of different application can be fulfilled. To ensure varieties application priority, concept of intra queue priority and inter queue priority are evolved. Node priority based hop by hop rate adjustment is also proposed here to ensure high link utilization. Finally experimental outputs have demonstrated the effectiveness of this task and show a noticeable performance in terms of energy analysis and throughput of the network.

Using explicit notification that indicates internal network conditions is a promising way to address the performance issues of congestion control in high-speed networks. In this paper, we propose SIRENS, a scalable, robust, and flexible fine-grained explicit notification framework. SIRENS is a per-hop and in-band notification scheme in which each router captures a snapshot of the various kinds of downstream link status along the IP-level path from a sender to a receiver and notifies the receiver of the status. The receiver can find out the overall path status by assembling all the cumulative notifications that indicate the status in each of the single hops and by feedback can share this information with the sender. Such per-hop information is needed by end-hosts if we are to flexibly design novel congestion control mechanisms or to significantly improve the performance of conventional forms of congestion control. We show that SIRENS can be used to configure TCP Limited Slow-Start and to improve the performance of multi-rate multicast congestion control.

This article outlines an approach for multicast congestion control based on an economic model that has been successfully applied to unicast congestion control. In this model, congestion signals are interpreted as prices and congestion-controlled sessions as utility maximizing agents. A naive extension of the unicast model fails to achieve a reasonable balance between providing the incentives necessary to promote the use of multicast and ensuring that multicast sessions do not interact too aggressively with unicast sessions. We extend the model by introducing a rational definition of multicast utility. The revised model provides a basis for multicast congestion control protocols that provide incentives to use multicast but are necessarily unfair to unicast traffic. We show, however, that the degree of unfairness can be controlled by appropriately setting a design parameter with a limiting case of strict fairness.

Teraflows over Gigabit WANs with UDT