Reliability (computer networking)

Abstract: This document provides an overview of the reliable multicast transport protocol II, RMTP-II. RMTP-II is a reliable multicast protocol, designed to reliably and efficiently send data from a few senders to large groups of simultaneous recipients. It works over both symmetric networks and asymmetrical network topologies such as those provided by satellite, cable modem, or ADSL carriers. Before sending, each sender must connect with a trusted top node to receive permission and control parameters for its data stream. The top node provides network managers with a single point of control for the senders, allowing them to monitor and control the traffic being sent. RMTP-II builds on a rich field of existing work, and adds to it the following novel contributions. It differentiates the roles of the nodes in the protocol, provides algorithms for smoothing and control of the return (TRACK) traffic, and provides explicit support for highly asymmetrical networks. It provides explicit network management controls through a centralized point of control, a fully distributed membership protocol that enables positive confirmation of data delivery, and fault recovery algorithms which are integrated to the reliability semantics of the protocol. It includes a novel reliability level called time bounded reliability, and offers a unique combination of TRACKs, NACKs, and FEC for increased scalability and real-time performance. Finally, it integrates distributed algorithms for RTT calculation to each receiver, and provides automatic configuration of receiver nodes.

Abstract: Vehicular Ad-hoc Networks (VANET) offer several user applications for passengers and drivers, as well as security and internet access applications. To ensure efficient data transmission between vehicles, a reliable routing protocol is considered a significant challenge. This paper suggests a new clustering-based routing protocol combining a modified K-Means algorithm with Continuous Hopfield Network and Maximum Stable Set Problem (KMRP) for VANET. In this way, the basic input parameters of the K-Means algorithm, such as the number of clusters and the initial cluster heads, will not be selected randomly, but using Maximum Stable Set Problem and Continuous Hopfield Network. Then the assignment of vehicles to clusters will be carried out according to Link Reliability Model as a metric that replaces the distance parameter in the K-Means algorithm. Finally, the cluster head is selected by weight function according to the amount of free buffer space, the speed, and the node degree. The simulation results have proved that the designed protocol performs better in a highway vehicular environment, compared to the most recent schemes designed for the same objective. In fact, KMRP reduces traffic congestion, and thus provides a significant increase in Throughput. In addition, KMRP decreases the transmission delay and guarantees the stability of the clusters in high density and mobility, which acts better in terms of the Packet Delivery Ratio.

Abstract: Internet of Things (IoT) is a promising paradigm to provide massive wireless connections in the future communications. One main feature of IoT is short packet communication (SPC), which adopts finite block-length codewords for data transmissions. Different from the long packet transmission (i.e., infinite block-length codewords) in conventional wireless networks, SPC suffers from a significant packet error rate even when the transmission rate is smaller than the Shannon capacity. To enhance the transmission efficiency as well as the reception reliability, we introduce cooperative relaying to the IoT network and propose a cooperative IoT protocol. Then, we analyze the average throughput of the cooperative IoT protocol with an approximated closed-form expression. Based on the closed-form expression, we design both optimal and suboptimal transmission rates to maximize the average throughput. Numerical and simulation results have validated the correctness of the theoretical analysis, and show that the maximum average throughput with the optimal/suboptimal design almost overlaps with the simulation results. Besides, we compare the proposed protocol with the automatic repeat request (ARQ) mechanism in terms of both the optimal transmission rate and the maximum average throughput, and observe that the proposed protocol outperforms the ARQ mechanism, especially for a medium/large number of cooperative users.

Abstract: This paper considers backbone network design under the constraints: minimal total link cost, and 1-FT (fault-tolerant to 1 link-failure). As networks become huge, the backbone layout design is essential to network performance and reliability. A 1-FT backbone can survive any 1-link failure. On the other hand, the total cost of the links in backbone layout is a practical concern. Therefore, the problem is to find a network topology for a set of nodes whose total link cost is minimized, subject to the condition that the backbone network can accommodate 1 link failure. The problem is NP-hard, and methods based on heuristic search are desired to obtain optimal or sub-optimal solutions. This paper proposes an efficient method based on genetic algorithms to solve the problem. The representation of a backbone layout is based on a list of ordered links. The genetic operators attempt to generate a more cost-effective or reliable layout. Simulation shows that the proposed algorithm can efficiently find a sub-optimal solution for most cases.