Packet Retransmission Mechanism Research Articles

Experimental Assessments of SDN-Enabled Optical Polling Flow Control for Contention Resolution in Optical DCNs

Due to the lack of optical buffer, high packer loss caused by packet contention is one of the main challenges for the optical switching data centers (DCs). Flow control (FC) protocol employing electrical buffers at the top of racks (ToRs) and exploiting packet retransmission mechanism in case of contention has been extensively investigated to decrease the packet loss in optical DCs. However, the packet retransmission and the head-of-line (HOL) blocking in electrical buffers at substantial load traffic introduce extra latency and buffer-overflow that still cause packet loss. To overcome these issues, a novel contention resolution technique based on a software-defined networking (SDN) enabled optical polling flow control is proposed and experimentally assessed in this article. Experimental assessments show that the proposed contention resolution scheme achieves zero packet loss and 7.4 μs latency performance at the load of 0.4. In addition, we numerically modelled and investigated the scalability of the proposed contention resolution technique in a large scale DCN based on the experimental parameters. Results prove the excellent scalability performance of OPFC scheme, in which the packet loss increases from 2.1E-3 to 9.02E-3 and the average latency increases 5.17 μs at the load of 0.5 as the OPFC based network scales from 4 to 40960 servers.

A Wireless Electricity Meter Reading Strategy Based on Lightweight IPv6

In order to reduce the networking time and improve the success rate of wireless electricity meter reading, a RPL routing control strategy based on lightweight IPv6 is proposed. A tree network topology is built by the strategy, and the IPv6 addresses of nodes are generated according to serials number of electricity meter and vendor code. The parent nodes are chosen by considering three routing metrics including the network depth, the strength of received signal and the Expected Transmission Count (ETX). In addition, a packet retransmission mechanism and concentrator file updating mechanism are adopted to improve the efficiency and success rate of electricity meter reading. The test results show that the wireless electricity meter reading strategy can construct the network rapidly and improve the efficiency of electricity meter reading.

Emergency wireless broadband random access performance analysis with packet retransmission mechanism

The random access channel model with retransmission packet mechanism is studied in the emergency wireless broadband access network (EWBAN). The success probability and access time delay packet request for MAC protocol access in EWBAN is analysed. The random access channel model with EWBAN retransmission packet mechanism and the MAC protocol is established using simulation results. Theoretical and engineering application guidance is provided for emergency wireless broadband communications.

An efficient fault tolerant mechanism to deal with permanent and transient failures in a network on chip

Recent advances in the silicon technology is enabling the VLSI chips to accommodate billions of transistors; leading toward incorporating hundreds of heterogeneous components on a single chip. However, it has been observed that the scalability of chips is posing grave problems for the current interconnect architecture which is unable to cope with the growing number of components on a chip. To remedy the inefficiency of buses, researchers have explored the area of computer networks besides exploring parallel computing to come up with viable solutions for billion transistor chips. The outcome is a novel and scalable communication paradigm for future System on Chips (SoCs) called as Network on Chips (NoC). However, as the chip scales, the probability of both permanent and temporary faults is also increasing, making Fault Tolerance (FT) a key concern in scaling chips. Alpha particle emissions, Gaussian noise on channels are some of the reasons which introduce transient faults in the data. Besides that, due to electromigration of conductors, corrosion or aging factors, on-chip modules or links may suffer permanent damage. This paper proposes a comprehensive solution to deal with both permanent and transient errors affecting the VLSI chips. On the one hand we present an efficient packet retransmission mechanism to deal with packet corruption or loss due to transient faults. On the other hand, we propose a deterministic routing mechanism which routes packets on alternate paths when a communication link or a router suffers permanent failure.

The study of QoS guarantee in the optical burst switching internet backbone

Optical switching technology can be categorized into optical circuit switching (OCS), optical packet switching (OPS) and optical burst switching (OBS). OCS is suitable for large amounts of data transmission; however, the channel utilization is inefficient when the traffic flows are intermittent. OPS can be easily adapted to any higher layer and is suitable for bursty traffic, but it requires a highly complex technology and optical buffer. The new switching paradigm, OBS, can provide higher bandwidth utilization and meanwhile avoid the complexity in OPS technology. In this paper, we investigate how the quality of service (QoS) can be guaranteed and reliable transmission can be supported in the OBS-based Internet backbone. We propose the adjustable-time-counter-based (ATCB) burst assembly and the non-real time packet retransmission mechanisms and apply them in the ingress router of the OBS Internet backbone to guarantee the quality of real time applications and lossless requirement of non-real time services. Moreover, traffic shaped is performed for real time packets in the egress router so that the real time property is preserved with a low jitter. Simulation results show that the burst blocking probability using the ATCB burst assembly is improved, compared with the time-counter-based (TCB) and burst-length-threshold-based (BLTB) mechanisms. The delay, loss and jitter of real time service conform to the QoS requirement. Meanwhile, the delay of non-real time service also falls in the acceptable range.