Optimization-based congestion control for multicast communications

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.

We consider the problem of congestion control in networks which support both multirate multicast sessions and unicast sessions. We present a decentralized algorithm which enables the different rate-adaptive receivers in different multicast sessions to adjust their rates to satisfy some fairness criterion. A one-bit ECN marking strategy to be used at the nodes is also proposed. The congestion-control mechanism does not require any per-flow state information for unicast flows at the nodes. At junctions nodes of each multicast tree, some state information about the rates along the branches at the node may be required. The congestion-control mechanism takes into account the diverse user requirements when different receivers within a multicast session have different utility functions, but does not require the network to have any knowledge about the receiver utility functions.

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.

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.

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.

ABSTRACTAlthough delay‐based congestion control protocols such as FAST Transmission Control Protocol (TCP) promise to deliver better performance than traditional TCP Reno, they have not yet been widely incorporated to the Internet. Several factors have contributed to their lack of deployment. Probably, the main contributing factor is that they are not able to compete fairly against loss‐based congestion control protocols. In fact, the transmission rate in equilibrium of delay‐based approaches is always less than their fair share when they share the network with traditional TCP Reno derivatives that employ packet losses as their congestion signal. There are also other performance impairments caused by the sensitivity to errors in the measurement of the congestion signal (queuing delay) that reduce the efficiency and the intra‐protocol fairness of the algorithms. In this paper, we report, analyse and discuss some recent proposals in the literature to improve the dynamic behaviour of delay‐based congestion control algorithms, FAST in particular. The coexistence of sources reacting differently to congestion, the identification of congestion appearance in the reverse path and thepersistent congestionproblem are the issues specifically addressed. Copyright © 2011 John Wiley & Sons, Ltd.

Low-latency, interactive media applications (e.g., video conferencing) present a unique set of challenges for congestion control. Unlike TCP, the transport mechanism for interactive media needs to adapt fast to abrupt changes in available bandwidth, accommodate sluggish responses and output rate fluctuations of a live video encoder, and avoid high queuing delay over the network. An ideal scheme should also make effective use of all types of congestion signals from the network, including packet losses, queuing delay, and explicit congestion notification (ECN) markings. This paper presents a unified approach for congestion control of interactive video: network-assisted dynamic adaptation (NADA). In NADA, the sender regulates its sending rate based on a composite congestion signal calculated and reported by the receiver, which combines both implicit (e.g., loss and delay) and explicit (e.g., ECN marking) congestion indications from the network. Via a consistent set of sender adaptation rules, the scheme can reap the full benefits of proactive, explicit congestion notifications supported by advanced queue management schemes. It remains equally responsive in the absence of such notifications. Extensive simulation studies show that NADA interact well with a wide variety of queue management schemes: conventional drop-tail, random early detection (RED), recently proposed CoDel (controlled delay) and PIE (Proportional Integral controller Enhanced), as well as a token-bucket-based random marking scheme based on Pre-Congestion Notification (PCN). Furthermore, NADA reacts fast to changes over the network, allows for weighted bandwidth sharing among multiple competing video streams, and sustains a substantial share of bottleneck bandwidth when coexisting with TCP.

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.

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.

In this chapter, layer-2 hop-by-hop congestion control mechanisms for wireless mesh networks are studied. First, background on development of congestion control as a research area is presented. Then, congestion is defined and the causes of congestion in a mesh network are identified. The steps and challenges for development of a congestion control protocol are explored by dividing congestion control mechanism into three main functions: congestion detection, signaling, and resolution. Stability and fairness in the context of rate control are studied, and global stability in the presence of delay is identified as the main challenge faced by hop-by-bop congestion control algorithms in multihop networks. The congestion control framework in the IEEE 802.11 draft standard on mesh networking is then presented. The chapter concludes with thoughts for practitioners and areas for future research in this field.

Network congestion causes severe transmission performance loss. Congestion control is the key to achieve low latency, high bandwidth and high stability. Due to the high regularity of topologies, datacenter networks contain abundant resources of equal-cost paths inherently and have huge potential for high-bandwidth transmission. Taking in-network telemetry (INT) information as the congestion signal, congestion control algorithms can monitor the network based on precise link load data. Hence the INT-based algorithm is the focus of recent high-precision congestion control research. However, existing INT-based congestion control algorithms handle the single-path transmission between the sender and the receiver, which cannot make full use of the abundant equal-cost paths resources in the network. In this paper, we make the first attempt to propose a multi-path INT-based congestion control algorithm, called MPICC. Compared with the most advanced INT-based congestion control algorithm HPCC, our method realizes multi-path coordinated transmission of data packets in datacenter networks. We conduct extensive experiments under various workloads to evaluate the performance of MPICC. The experimental results show that under the condition of ensuring high throughput of end hosts, MPICC is able to use multi-path to transmit data packets, which greatly reduces the flow completion time (FCT) of the flow in the network. Specifically, under three common datacenter workloads, Cache Follower, Web Search and Web Server, MPICC reduces the average flow completion time of the network by 20.1%, 14.4%, and 39.5%, respectively, and shortens the 97th-percentile flow completion time by 39.9%, 18.9% and 57.9%, respectively.KeywordsCongestion controlIn-network telemetry (INT)Multi-pathDatacenter networksProgrammable switch

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.

This paper proposes and investigates the performance of a combined preventive / reactive congestion control approach for high-speed LAN / MAN interconnection networks. The interconnection of low-speed LANs via a high-speed MAN faces a speed-mismatch. As the primary control component, the preventive rate control mechanism is designed to cope with the speed-mismatch problem by throttling the long-term average input traffic injected into the backbone network under a large propagation delay constraint. The reactive feedback control component complements the preventive rate control to enhance the overall congestion control performance. Simulation results demonstrate the effectiveness of the proposed congestion control approach under different traffic conditions.KeywordsLANMANinterconnectionnetworkspreventivereactivecongestion control

Congestion control (CC) is essential for achieving ultra-low latency, high bandwidth, and network stability in high-speed networks. However, modern high-performance RDMA networks, crucial for distributed applications, face significant performance degradation due to limitations of existing CC schemes. Most conventional approaches rely on congestion notification signals that must traverse the queuing data path before congestion signals can be sent back to the sender, causing delayed responses and severe performance collapse. This study proposes Explicit Notification Congestion Control (ENCC), a novel high-speed CC mechanism that achieves low latency, high throughput, and strong network stability. ENCC employs switches to directly notify the sender of precise link load information and avoid notification signal queuing. This allows precise sender-side rate control and queue regulation. ENCC also ensures fairness and easy deployment in hardware. We implement ENCC based on FPGA network interface cards and programmable switches. Evaluation results show that ENCC achieves substantial through-put improvements over representative baseline algorithms, with gains of up to 16.6× in representative scenarios, while incurring minimal additional latency.

With the emergence of delay-sensitive applications like cloud gaming, remote driving, and virtual/augmented reality (VR/AR), there has been renewed research interest in the development of low latency congestion control protocols. However, these efforts have been impeded by the difficulty associated with designing an end-to-end protocol that reacts to delay signals, but that also shares a link effectively (i.e., without causing harm to other flows and without being starved by other flows). This is a critical requirement for use in the public internet. To help protocol designers, we summarize the literature on coexistence of delay-based congestion controls. We implement a selection of the coexistence techniques described in the literature, and evaluate them in a set of controlled experiments designed to showcase the benefits and limitations of each approach. Through our experimental analysis, we highlight coexistence-related pitfalls of delay as a congestion signal. We hope that this work will help inform the design of new low latency congestion control protocols or improvements to existing protocols.