Faculty Publications
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Item Congestion control mechanisms in vehicular networks: A perspective on Internet of vehicles (IoV)(Elsevier, 2022) Patil, A.; Muthuchidambaranathan, P.; Shet, N.S.V.Developing congestion control in highly mobile vehicular networks is a challenging task. The network of vehicles or heavy vehicles uses different data for communication depending on the required application. These networks are one of the main components of the Internet of Things (IoT), and the aim is to connect every vehicle to every other vehicle for the purpose of improving the user’s quality of life. To provide better network accessibility, channel utilization, and speedy delivery of the information over these networks, congestion control plays a significant role. In this chapter, we present various congestion control mechanisms for vehicular networks by considering different applications in these networks. The decentralized and centralized mechanisms are presented and their use in different types of vehicular networks is also suggested. In the end, we have listed some challenges to help researchers to expand their research in this area. © 2022 Elsevier Inc.Item Ant-CAMP: Ant based congestion adaptive multi-path routing protocol for wireless networks(2011) Raval, C.; Hegde, S.; Tahiliani, M.P.The advent of mobile computing devices and wide deployment of wireless networks have led to an exponential increase in the internet traffic. Long congestion epochs and frequent link failures in wireless network lead to more number of packets being dropped and incur high end-to-end delay, thereby degrading the overall performance of the network. Congestion control, though mainly incorporated at the transport layer, if coupled with the routing protocols, can significantly improve overall performance of the network. In this paper we propose Ant based Congestion Adaptive Multipath (Ant-CAMP) routing protocol that aims to avoid congestion by proactively sending congestion notification to the sender. The proposed Ant-CAMP routing protocol is implemented in Network Simulator-2 (NS-2) and its performance is compared with Ad-hoc On Demand Multi-Path Distance Vector (AOMDV) in terms of Packet Drops due to Congestion, Packet Delivery Fraction and Average End-to-End Delay. © Springer-Verlag 2011.Item Design and implementation of TCP BBR in ns-3(Association for Computing Machinery acmhelp@acm.org, 2018) Jain, V.; Mittal, V.; Tahiliani, M.P.Bottleneck Bandwidth and Round-trip propagation time (BBR) is a congestion based congestion control algorithm recently proposed by Google. Although it can be deployed with any transport protocol that supports data delivery acknowledgement, BBR is presently implemented alongside TCP (known as TCP BBR) in Linux kernel since 4.9 and is the default congestion control used in Google Cloud Platform. However, to the best of our knowledge, TCP BBR is not yet supported in popular network simulators such as ns-3. This limitation is a major hindrance in thoroughly studying the benefits of TCP BBR since carrying out large-scale and real-time experimental evaluations is a non-trivial task. In this paper, we discuss the design and implementation of a new model for TCP BBR in ns-3. We validate the proposed model by performing different sets of simulations to ensure that the model in ns-3 exhibits key characteristics of TCP BBR. © 2018 Copyright held by the owner/author(s).Item QUIC Protocol Performance in Wireless Networks(Institute of Electrical and Electronics Engineers Inc., 2018) Kharat, P.; Rege, A.; Goel, A.; Kulkarni, M.Google's Quick UDP Internet Connections QUIC transport layer protocol was developed in 2013 as a successor to its own SPDY networking protocol, which itself led to the formation of the HTTP/2 standard. QUIC's main motives were to take the advantages of TCP/IP and HTTP/2, and build them over UDP, in terms of reliability, flow control, and congestion control. The primary objective of this paper is to explore QUIC functionalities to suggest techniques to improve throughput, speedup and efficiency in wireless networks. The experimental results were established on a local test bed setup connected to a wireless access point in a campus network environment. Experimental results show that QUIC performance in the form of throughput and speedup over TCP/IP in live network environment. The fairness of QUIC in competing flow situations is also examined, and found to perform well in long life traffic. We also propose the reintroduction of FEC for minimization of retransmission latencies. © 2018 IEEE.Item A principled look at the utility of feedback in congestion control(Association for Computing Machinery, 2019) Tahiliani, M.P.; Misra, V.; Ramakrishnan, K.K.Networked applications are ubiquitous and their performance requirements are becoming increasingly stringent. Network congestion can seriously impact performance contributing to increased latency, packet loss and poor throughput. To address these problems, the networking community has come up with a large number of congestion control algorithms. Congestion control schemes developed over the past few decades can be classified into two broad classes: one based on an end-system's perception of network congestion and the other based on the network providing feedback to flows that pass through it. In this paper, we make the observation that the pure end-system based congestion control schemes are faced with the significant challenge of receiving ambiguous signals that make it difficult to infer where the congestion is occurring and if this flow is even the cause of that congestion. This ambiguity makes it difficult for pure end-system based control schemes to achieve fairness across different flows. Modern routers and switches in the meantime, have grown in computing capability and can generate fine grained feedback at line speeds for flows traversing them. We show that even relatively simple feedback generated in-network at the point of congestion eliminates the ambiguities faced by pure end-system based congestion control mechanisms, thus ensuring the network functions at the right fair and efficient operating point. We provide the theoretical underpinnings establishing the need for in-network feedback to enable the network to operate at a unique fixed point at the intersection of the desired fair and efficient operation regimes, and demonstrate through emulation experiments that our use of the well-established and studied PI-control for Active Queue Management and Explicit Congestion Notification meets the goals of low latency, high throughput and fine granularity control of the queue while achieving fairness. © 2019 Copyright held by the owner/author(s). Publication rights licensed to ACM.Item Congestion controlling schemes for high-speed data networks: A survey(IOS Press Nieuwe Hemweg 6B Amsterdam 1013 BG, 2019) Kharat, P.; Kulkarni, M.The data networks are basically designed with the aim of maximum throughput and fair resource allocation by managing available resources. A transport layer plays an important role in throughput and fairness with the help of congestion control algorithms (variants). This survey targets mainly congestion issues in high-speed data networks to improve efficiency at connection or flow level. Transmission Control Protocol (TCP) is a dominating transport layer protocol in the existing network because of its reliable service and deployment in most of the routers. A cause of congestion may be different in wired and wireless network and needs to be handled separately. Packet delay, packet loss and time out (RTO) are not caused by congestion in case of wireless network. This has been taken into account in our consideration. To overcome the dominance of TCP, Google proposed UDP based solution to handle congestion control and reliable service with minimum latency and control overhead. In the literature several methods are proposed to classify transport layer Protocols. In this survey congestion control proposals are classified based on situation handled by the algorithm such as pure congestion, link loss, packet reordering, path optimization etc. and at the end congestion control at flow level has been addressed. © 2019 - IOS Press and the authors.Item Geometric Series based effective RTO estimation Technique for CoCoA(Elsevier B.V., 2022) Rathod, V.; Tahiliani, M.P.Constrained Application Protocol (CoAP) is a standard data transfer protocol for Internet of Things. It has an in-built support for the basic congestion control mechanism that uses fixed Retransmission Time Out (RTO) for every transmission regardless of Round Trip Time (RTT), and performs Binary Exponential Backoff (BEB) when the packets get dropped. CoAP Simple Congestion Control/Advanced (CoCoA) is an enhanced congestion control mechanism over CoAP that adapts RTO based on RTT. It maintains Strong and Weak RTO estimators and uses a Variable Backoff Factor (VBF) instead of BEB when the packets get dropped. CoCoA uses an Exponential Weighted Moving Average (EWMA) to estimate the RTO for the next transmission. The weight used in EWMA is determined on the basis of whether the RTT estimated for the recent transmission was a Strong RTT or Weak RTT. However, the weights used to estimate the RTO are fixed (0.5 for Strong and 0.25 for Weak). These fixed weights lead to slow adaptation of RTO and affect the performance of the IoT applications. In this paper, we highlight the impact of having fixed weights while estimating the RTO in CoCoA. In particular, we show that the RTO in CoCoA fails to adapt quickly when the network conditions are lossless because it uses a fixed value for Strong RTO estimation (0.5). We propose a new algorithm called Geometric Series based effective RTO estimation Technique for CoCoA (GSRTC) to adapt the weight used in EWMA for estimating Strong RTO. GSRTC is integrated into CoCoA and validated against existing mechanisms using the Cooja simulator in Contiki OS and in a real testbed FIT/IoT-LAB. Our results show that GSRTC has lower Flow Completion Times (FCT), lesser retransmissions and better network throughput. © 2022 Elsevier B.V.