Maximum Transmission Unit Size Research Articles

Hybrid error correction in fragmented IoT media streams

AbstractWireless personal area networks (WPANs), as most IoT networking technologies, rely on constrained low power devices that support a trade‐off between signal coverage and transmission rates. WPANs are characterized for medium to low transmission rates over low distances. The transmission rates, however, are high enough to support maximum transmission unit (MTU) sizes that are large enough to enable the transmission of IPv6 datagrams. One such WPAN technologies is associated with the IEEE 802.15.4 physical layer. Because IEEE 802.15.4 does not natively support IP encapsulation, an adaptation mechanism known as IPv6 over low‐power wireless personal area networks (6LoWPAN) is used to this end. For large datagrams like those generated when transmitting speech frames, 6LoWPAN fragments them in order to comply with the 127‐byte IEEE 802.15.4 MTU size. Fragmentation, however, aggravates the effects of network packet loss. This article explores this problem and attempts to find a mechanism that overcomes these limitations. Specifically, it introduces a hybrid error correction algorithm that dynamically adjusts the number of fragments that are transmitted in order to balance application layer loss and transmission rate.

Means and Methods of Efficiency Estimation of Video Stream Transmission Based on GigE Vision Technology Using Application Processor

The paper investigates the possibility of efficient implementation of a GigE Vision compatible video stream source on a computing platform based on a system-on-a-chip with general-purpose ARM processor cores. In particular, to implement the aforementioned video source, a proprietary prototype of a GigE Vision compatible camera was developed based on the Raspberry Pi 4 single-board computer. This computing platform was chosen due to its widespread use and wide community support. The software part of the camera is implemented using the Video4Linux and Aravis libraries. The first library is used for the primary image capturing from a video sensor connected to a single board computer. The second library is intended for forming and transmission of video stream frames compatible with GigE Vision technology over the network. To estimate the delays in the transmission of a video stream over an Ethernet channel, a methodology based on the Precise Time Protocol (PTP) has been proposed and applied. During the experiments, it was found that the software implementation of a GigE Vision compatible camera on single-board computers with general-purpose processor cores is quite promising. Without additional optimization, such an implementation can be successfully used to transmit small frames (with a resolution of up to 640 × 480 pixels), giving a delay less than 10 ms. At the same time, some additional optimizations may be required to transmit larger frames. Namely, a MTU (maximum transmission unit) size value plays the crucial role in latency formation. Thus, to implement a faster camera, it is necessary to select a platform that supports the largest possible MTU (unfortunately, it turned out that it is not possible with Raspberry Pi 4, as it supports relatively small MTU size of up to 2000 bytes). In addition, the image format conversion procedure can noticeably affect the delay. Therefore, it is highly desirable to avoid any frame processing on the transmitter side and, if it is possible, to broadcast raw images. If the conversion of the frame format is necessary, the platform should be chosen so that there are free computing cores on it, which will permit to distribute all necessary frame conversions between these cores using parallelization techniques.

MTU configuration for real-time switched Ethernet networks

We motivate and formulate the effect of MTU size configuration on the response time of messages crossing through a HaRTES architecture.We propose a search-based approach, with two techniques to reduce the search space, to find the optimum MTU size.We propose a heuristic algorithm with pseudo polynomial time complexity to find the best MTU targeting a shorter response time for messages.We experimentally show that the heuristic algorithm finds MTU sizes such that the response time of messages is improved around 30 %.We experimentally show that the heuristic algorithm performs as good as the search-based algorithm as a reference. In this paper, we show that in real-time switched Ethernet networks reducing the Maximum Transmission Unit (MTU) size may cause an increase or decrease in the response time of messages. This contradicting behavior arises an optimization problem for configuring the MTU size. We formulate the optimization problem in the context of the multi-hop HaRTES architecture, which is a hard real-time Ethernet protocol. As part of the solution, we propose a search-based algorithm to achieve optimum solutions. We modify the algorithm by presenting two techniques to reduce the search space. Then, we propose a heuristic algorithm with a pseudo-polynomial time complexity based on the search-based algorithm. We perform several experiments, and we show that the proposed heuristic results in an improvement regarding messages response times, compared with configuring the MTU to the maximum or minimum values. Moreover, we show in small network configurations that the heuristic performs as good as the search-based algorithm in many cases.

An Overview of Tiles in HEVC

Tiles is a new feature in the High Efficiency Video Coding (HEVC) standard that divides a picture into independent, rectangular regions. This division provides a number of advantages. Specifically, it increases the “parallel friendliness” of the new standard by enabling improved coding efficiency for parallel architectures, as compared to previous sliced based methods. Additionally, tiles facilitate improved maximum transmission unit (MTU) size matching, reduced line buffer memory, and additional region-of-interest functionality. In this paper, we introduce the tiles feature and survey the performance of the tool. Coding efficiency is reported for different parallelization factors and MTU size requirements. Additionally, a tile-based region of interest coding method is developed.

Optimum UDP Packet Sizes in Ad Hoc Networks

Ad hoc networks are comprised of MAC, routing protocols and physical environments. In this paper, optimum MTU (Maximum Transmission Unit) sizes are studied in the ad hoc network environment. For a performance index, the throughput rate is defined. The throughput rate is the ratio between the number of packets received and packets sending through the overall systems. MTUs with the sizes between 250 bytes and 750 bytes have been shown to have better throughput rates in the environment without noise. MTUs with the size of 500 bytes have been found to generate the optimum throughput rate in the environments of 10 -4 BER or less. Similar results are obtained in lower BER environments. AODV has slightly better performance than DSR without noise. These results found to be true for practical mobile environment.