Reordering Delay Research Articles

Proxy Path Scheduling and Erasure Reconstruction for Low Delay mmWave Communication

In 5G and future cellular systems, use of multiple millimeter-wave (mmWave) links in parallel can enable interactive applications that demand consistent low delays with very high data rates. In previous work we introduced a mmWave multipath proxy that preemptively manages a set of mmWave paths to guarantee a steady data rate with high confidence. Here we explore the impact choice of packet sending path has on packet delay in this dynamic system, as well as the potential benefits <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">erasure reconstruction codes</i> (ERC) may provide in mitigating packet reordering delays at the receiver. We find that capacity aware scheduling improves packet delay, but that improvements diminish relative to the staleness of the capacity knowledge. ERC almost completely eliminates head-of-line blocking delays at the receiver, but any benefit is diminished by additional queueing delays induced by parity packets, unless they are selectively sent according to available capacity.

A Low-Latency MPTCP Scheduler for Live Video Streaming in Mobile Networks

It is a known issue that low-latency communication is hard to achieve when using multiple network interfaces with asymmetric capacity and delay (e.g., LTE and WLAN) simultaneously. A main underlying cause of this issue is that the packets with lower sequence number are stalled on a high-latency path, thus the early arriving packets with higher sequence number become &#x201C;out-of-order (OFO)&#x201D; packets. These OFO packets may excessively consume receiver&#x2019;s buffer, causing long reordering delay and unnecessary packet retransmission. In this paper, we present a novel design of packet scheduling for Multipath TCP (MPTCP), called OverLapped Scheduler (OLS), able to tackle the OFO-packet problem more effectively. OLS can guarantee sufficient throughput on demand of upper layer applications, and utilizes the remaining bandwidth to reduce OFO-packets. To do so, OLS schedules packets according to their arrival time and sends a controlled number of redundant packets to avoid the impact of inaccurate arrival-time estimations due to network jitter. We implement OLS in a Linux kernel, and the experiments show that in asymmetric networks with or without jitter, OLS can effectively reduce OFO-packets and transmission latency while maintaining a sufficient throughput, which makes it fully capable to meet the requirements of applications such as live video streaming.

Low-Delay Scheduling for Internet of Vehicles: Load-Balanced Multipath Communication With FEC

The proliferation of devices with multiple wireless interfaces and (automobile) manufacturers’ interest in implementing reliable connectivity for vehicles create an ideal scenario for multipath transmission control protocol (MPTCP) over vehicular networks. Next generation vehicular networks will be highly dynamic and exploit MPTCP over various wireless technologies including WiFi and 5th generation (5G) cellular networks to form the Internet of vehicles (IoV). However, the probability of packet loss can be high and/or packets arrive at the destination out-of-order due to time-varying heterogeneous wireless paths. Further, the IoV traffic is delay sensitive, which urges the need to investigate MPTCP algorithms for reliable communication over heterogeneous lossy networks, while satisfying delay constraints. We approach these challenges by jointly using load balancing and forward error correction (FEC) for performing coupled congestion control inside MPTCP. As a result, the proposed MPTCP-IoV is TCP-friendly by design, and provably stable and convergent to a unique equilibrium point. In addition, a comprehensive mathematical analysis (developed to approximate the reordering delay) is carried out and shown that the delay penalty for MPTCP-IoV over such networks becomes insignificant when considering the potential gains obtained by the convergence of multiple networks. Experiments are carried out and the results demonstrate these characteristics.

Minimum information rate for observability of linear systems with stochastic time delay

ABSTRACTThis paper investigates the state estimation problem for linear time-invariant systems where sensors and controllers are geographically separated and connected via stationary memoryless uncertain digital communication channels with the information rate limitation. Such channels introduce data packet dropout, stochastic time delay, and data packet reordering. In the TCP/IP model, the transport layer provides a reliable service on top of an unreliable communication channel. However, the performance of such systems is still affected by packet reordering and stochastic time delay. In particular, we present an optimal encoding and decoding scheme to guarantee observability by employing the minimum information rate, and derive a necessary and sufficient condition on the delay distribution and information rate for observability. Illustrative examples are given to demonstrate the effectiveness of the proposed scheme.

Scaling Multi-Core Network Processors without the Reordering Bottleneck

Today, designers of network processors strive to keep the packet reception and transmission orders identical, and therefore avoid any possible out-of-order transmission. However, the development of new features in advanced network processors has resulted in increasingly parallel architectures and increasingly heterogeneous packet processing times, leading to large reordering delays. In this paper, we introduce novel scalable scheduling algorithms for preserving flow order in parallel multi-core network processors. We show how these algorithms can reduce reordering delay while adapting to any load-balancing algorithm and keeping a low implementation complexity overhead. To do so, we use the observation that all packets in a given flow have similar processing requirements and can be described with a constant number of logical processing phases. We further define three possible knowledge frameworks of the time when a network processor learns about these logical phases, and deduce appropriate algorithms for each of these frameworks. Finally, we model our proposed algorithms and simulate them under both synthetic traffic and real-life traces, and show that they significantly outperform past approaches.

Can COTS Ethernet Switches Handle Uncompressed Video?

The carriage of realtime video over Ethernet networks promises significant benefits to the broadcast industry. But there has been some concern about whether commercial-off-the-shelf Ethernet switches can meet broadcast quality of service requirements. This paper describes the results of a range of static and dynamic tests of Ethernet switches using packet flows that are representative of uncompressed high-definition video encapsulated in SMPTE 2022-6, looking specifically at packet loss, packet reordering, latency, and packet delay variation. Flow test generators and analyzers include a new flexible field-programmable gate array architecture, controlled using a RESTful application programming interface.

Path Restoration Schemes for MPLS Networks

The authors have presented an overview and simulation of several path restoration schemes for MPLS networks. Each scheme has its own advantages and disadvantages that make them appropriate for different applications. These characteristics include recovery time in case of failure, packet loss, packet reordering, and recovery delay. The decision of implementing some of these schemes in a real network depends on how much resources are available and the requirements of the network user's. Furthermore, simulation results based on OMNET+ + show that the simple dynamic scheme has the lowest arrival time when compared to the other reported path restoration schemes. Future work will be focused on investigating further comparisons and enhancements of these schemes.

Multi-path transmission control scheme combining bandwidth aggregation and packet scheduling for real-time streaming in multi-path environment

These days, a wide variety of wireless interfaces are available to connect to Internet. When coverage area of these different technologies overlap, receiver equipped with multiple interfaces can use them simultaneously to improve the performance of its applications in terms of bandwidth rely on bandwidth aggregation. However, specific conditions such as bottleneck bandwidth and end-to-end delay need to be accounted for before using such techniques. If this problem of end-to-end delay and bottleneck bandwidth are not properly addressed, there may be many packets along multiple paths which can arrive late and can lead to a large number of out-of-order packets at the receiver, which can eventually cause serious degradation of video quality at the receiver. For this reason, in this study, the authors propose a multi-path transmission control scheme (MTCS) combining bandwidth aggregation and packet scheduling for real-time streaming in a multi-path environment. In a bandwidth aggregation scheme, the authors propose a mathematical model to find the transmission rate over each path in order to obtain the optimal total throughput. However, the end-to-end delay of each path is not the same. The out-of-order packets problem will become serious in a multi-path environment. Therefore the authors propose a packet scheduling scheme to arrange the transmission sequence in order to effectively minimise the impact of packet reordering at the receiver. Our proposed control scheme not only aggregates the available bandwidth of multiple paths, but also reduces the time of packet reordering at the receiver. Experimental results show with our proposed scheme, the authors not only obtain the optimal transmission throughput but also reduce packet reordering delays under varying drop and delay conditions caused by the underlying network.

Feedback-based traffic splitting for wireless terminals with multi-radio devices

It is expected that a number of heterogeneous radio access technologies will be available simultaneously at a single wireless terminal in next generation wireless networks. This paper addresses the challenge of link aggregation in a wireless terminal with multi-radio devices. A major issue in multi-path transmission is how to reduce the additional reordering delay at the receiver, which is mainly caused by the difference between link delays. This is particularly critical in wireless environments due to dynamics in link quality. Motivated by this observation, we propose a feedback-based technique to determine split ratios adaptively, based on measurements at the receiver. The link-level packet delay is measured on a periodic basis. The measurement is conveyed to the sender, and is used for split ratio calculation. The proposed technique has been implemented into an actual test-bed network which includes WiMAX and WiFi systems, and its potential usefulness is extensively evaluated. It was experimentally verified that for given radio link conditions, the traffic split ratio between WiMAX and WiFi links is optimally converged.

Bandwidth Aggregation-Aware Dynamic QoS Negotiation for Real-Time Video Streaming in Next-Generation Wireless Networks

In next generation wireless networks, Internet service providers (ISPs) are expected to offer services through several wireless technologies (e.g., WLAN, 3G, WiFi, and WiMAX). Thus, mobile computers equipped with multiple interfaces will be able to maintain simultaneous connections with different networks and increase their data communication rates by aggregating the bandwidth available at these networks. To guarantee quality-of-service (QoS) for these applications, this paper proposes a dynamic QoS negotiation scheme that allows users to dynamically negotiate the service levels required for their traffic and to reach them through one or more wireless interfaces. Such bandwidth aggregation (BAG) scheme implies transmission of data belonging to a single application via multiple paths with different characteristics, which may result in an out-of-order delivery of data packets to the receiver and introduce additional delays for packets reordering. The proposed QoS negotiation system aims to ensure the continuity of QoS perceived by mobile users while they are on the move between different access points, and also, a fair use of the network resources. The performance of the proposed dynamic QoS negotiation system is investigated and compared against other schemes. The obtained results demonstrate the outstanding performance of the proposed scheme as it enhances the scalability of the system and minimizes the reordering delay and the associated packet loss rate.

Modelling and robust stability of networked control systems with packet reordering and long delay

In this article, modelling and robust stability of networked control systems (NCS) are discussed. Considering the existence of packet reordering and network-induced delay, a new mathematical model of NCS whose network-induced delay is longer than one sampling period is obtained, which can fully describe packet reordering and effectively eliminate the impact of packet reordering on the performance of NCS such that the newest control input can be executed by the actuator. Based on this model, the time-varying NCS is converted into an uncertain discrete linear system with multi-step delay in terms of matrix theory. Furthermore, a sufficient condition for robust stability of NCS is presented. Linear matrix inequality approach has been employed to solve the controller design problems. Numerical examples are compared with previous schemes to demonstrate the effectiveness of the proposed method.