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Copa-D: Delay Consistent Copa for Dynamic Cellular Networks
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).ORCID iD: 0000-0001-8947-0399
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).ORCID iD: 0000-0003-4147-9487
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).ORCID iD: 0000-0002-0722-2656
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Mathematics and Computer Science (from 2013).ORCID iD: 0000-0002-8731-2482
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2023 (English)Manuscript (preprint) (Other academic)
Abstract [en]

The lack of consideration for application delay requirements in standard loss-based congestion control algorithms (CCAs) has motivated the proposal of several alternative CCAs. As such, Copa is one of the most recent and promising CCAs, and it has attracted attention from both academia andindustry. The delay performance of Copa is governed by amostly static latency-throughput tradeoff parameter, δ. However,a static δ parameter makes it difficult for Copa to achieve consistent delay and throughput over a range of bottleneck bandwidths. In particular, the coexistence of 4G and 5G networks and the wide range of bandwidths experienced in NG-RANs can result in inconsistent CCA performance. To this end, we propose a modification to Copa, Copa-D, that dynamically tunes δ to achieve a consistent delay performance. We evaluate the modification over emulated fixed, 4G, and 5G bottlenecks. The results show that Copa-D achieves consistent delay with minimal impact on throughput in fixed capacity bottlenecks. Copa-D also allows a more intuitive way of specifying the latency-throughput tradeoff and achieves more accurate and predictable delay invariable cellular bottleneck.

Place, publisher, year, edition, pages
2023.
Keywords [en]
Copa, Delay, Throughput, 4G, 5G, QUIC
National Category
Computer Sciences
Research subject
Computer Science
Identifiers
URN: urn:nbn:se:kau:diva-94025OAI: oai:DiVA.org:kau-94025DiVA, id: diva2:1746565
Conference
2023 European Conference on Networks and Communications & 6G Summit (EuCNC/6G Summit)
Available from: 2023-03-28 Created: 2023-03-28 Last updated: 2023-05-15Bibliographically approved
In thesis
1. Achieving Low Latency and High Throughput over Cellular Internet Connections
Open this publication in new window or tab >>Achieving Low Latency and High Throughput over Cellular Internet Connections
2023 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The continuous increase in the number and type of Internet services and their requirements for improved QoS has motivated the steady evolution  of cellular networks towards the current fifth generation (5G) systems. However, updating the network to 5G is insufficient to satisfy application requirements since performance limitations can also exist in the transport used by the applications. Legacy transport protocols and congestion control algorithms (CCAs) are not suitable for applications with requirements for both throughput and delay. This mismatch has inspired new transport protocols and CCAs, such as QUIC and BBR. Nevertheless, cellular networks present challenges that can make it difficult for newly proposed CCAs to achieve consistent throughput and delay.       

The main focus of this thesis is enhancing transport protocols and CCAs to achieve lower delay and high throughput in cellular networks. An extensive review of available end-to-end CCAs for cellular networks is provided in this thesis, along with the challenges and future directions for research. The delivery rate at a receiver is an important quantity that has found increased use in modern CCAs, and in this thesis, we propose and validate a Kalman-filter-based technique to obtain a steady estimate of the delivery rate for a cellular bottleneck. This thesis also proposes an extension to the QUIC protocol to make receiver-side delivery rate estimates available to the sender CCAs. Using the proposed rate estimation method and extension to the QUIC protocol, this thesis proposes modifications to the recently proposed CCAs BBR and Copa. The proposed modifications are evaluated over real cellular networks and through extensive trace-based emulations. The modified BBR results in lower packet delays with similar throughput to standard BBR in cellular bottlenecks. On the other hand, the modification to Copa strives to provide a more consistent and predictable delay performance across different cellular bottlenecks. 

Abstract [en]

The continuous increase in the number and type of Internet services and their requirements for improved QoS has driven the evolution of cellular networks towards the fifth-generation (5G) systems. However, updating the network to 5G is insufficient to satisfy application requirements since legacy transport protocols and congestion control algorithms (CCAs) are not suitable for applications with requirements for both throughput and delay.  

In this thesis, we aim to enhance transport protocols and CCAs to achieve low delay and high throughput in cellular networks. We provide an extensive review of contemporary end-to-end CCAs for cellular networks, along with the challenges in designing suitable CCAs and future directions for research. We also propose a technique to obtain a steady estimate of the delivery rate for a cellular bottleneck and an extension to one of the major transport protocols of the Internet (QUIC). The proposed extension makes receiver-side delivery rate estimates available to the sender CCAs.  

Using the proposed rate estimation method and extension to the QUIC protocol, we propose modifications to two prominent modern CCAs, i.e. BBR and Copa. Through extensive evaluation, this thesis shows that the modified BBR results in lower packet delays, and the modification to Copa provides a more consistent and predictable delay performance.

Place, publisher, year, edition, pages
Karlstads universitet, 2023. p. 45
Series
Karlstad University Studies, ISSN 1403-8099 ; 2023:11
Keywords
QUIC, BBR, Copa, TCP, Congestion control, Throughput, Queuing Delay, Performance Evaluation, 4G, 5G, Kalman Filter
National Category
Computer Sciences
Research subject
Computer Science
Identifiers
urn:nbn:se:kau:diva-94024 (URN)978-91-7867-364-3 (ISBN)978-91-7867-365-0 (ISBN)
Public defence
2023-05-29, 1B306, Fryxellsalen, 09:30 (English)
Opponent
Supervisors
Available from: 2023-05-09 Created: 2023-03-28 Last updated: 2023-05-09Bibliographically approved

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Haile, Habtegebreil KassayeGrinnemo, Karl-JohanFerlin, SimoneHurtig, PerBrunström, Anna

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