Minimum Transmission Delay Research Articles

An Effective Evolutionary Approach for Bicriteria Shortest Path Routing Problems

Routing problem is one of the important research issues in communication network fields. In this paper, we consider a bicriteria shortest path routing (bSPR) model dedicated to calculating nondominated paths for (1) the minimum total cost and (2) the minimum transmission delay. To solve this bSPR problem, we propose a new multiobjective genetic algorithm (moGA): (1) an efficient chromosome representation using the priority-based encoding method; (2) a new operator of GA parameters auto-tuning, which is adaptively regulation of exploration and exploitation based on the change of the average fitness of parents and offspring which is occurred at each generation; and (3) an interactive adaptive-weight fitness assignment mechanism is implemented that assigns weights to each objective and combines the weighted objectives into a single objective function. Numerical experiments with various scales of network design problems show the effectiveness and the efficiency of our approach by comparing with the recent researches.

Streaming-Viability Analysis and Packet Scheduling for Video Over In-Vehicle Wireless Networks

State-of-the-art vehicles are now being equipped with multiple video channels for video-data transmission from multiple surveillance cameras mounted on the automobile, navigation videos reporting the traffic conditions on the planned route, as well as entertainment-multimedia streaming for passengers watching on rear-seat monitors. Wireless LANs provide a low-cost and flexible infrastructure for these emerging in-vehicle multimedia services aimed at the driver's and passengers' safety, convenience, and entertainment. To enable the successful simultaneous deployment of such applications over in-vehicle wireless networks, we propose delay-sensitive streaming and packet-scheduling algorithms that enable simple, flexible, and efficient adaptation of the video bitstreams to the instantaneously changing video source and wireless-channel characteristics while complying with the a priori negotiated quality-of-service (QoS) parameters for that video service. Our focus is on real-time low-cost solutions for multimedia transmission over in-vehicle wireless networks that are derived based on existing protocols defined by QoS-enabled networks, such as the IEEE 802.11e standard. In addition, the aim of this paper is to couple the proposed solutions with a novel multitrack-hinting method that is proposed as an extension of conventional MP4 hint tracks in order to provide real-time adaptation of multimedia streams to multiple quality levels for different in-vehicle applications, depending on their importance and delay constraints. First, the scheduling constraints for these simultaneous wireless video-streaming sessions are analytically expressed as a function of the negotiated QoS parameters. This is imperative because a video stream received from an in-vehicle road-surveillance camera will have a different set of delay and quality constraints in comparison to that of traffic monitoring received from remote video cameras located on the planned route. Hence, transmission parameters, such as peak data rate, maximum burst size, minimum transmission delay, maximum error rate, etc., will differ for the various video streams. For this reason, new low-complexity packet-scheduling algorithms that can fulfill diverse QoS streaming conditions are proposed and analyzed. The proposed algorithms produce viable schedules (i.e., strictly QoS-compliant) that jointly consider the delay constraints and the in-vehicle video-receiver-buffer conditions. Hence, these scheduling schemes can completely avoid the underflow or overflow event of the receiving-device buffer while guaranteeing the agreement between the real-time video traffic and the predetermined traffic specification reached during QoS negotiation for various in-vehicle video channels. When combined with multitrack hinting, an integrated flexible system for adaptive multimedia streaming over QoS-enabled in-vehicle wireless networks can be constructed. We demonstrate the viability of the proposed scheduling mechanisms experimentally by using real video traces under multiple quality levels, as derived by the multitrack-hinting design. In addition, simulations under realistic conditions are also performed to validate the ability of the method to satisfy buffer-occupancy constraints.

A distributed routing protocol for providing QoS in Wireless Mesh Networks operating above 10 GHz

AbstractWireless Mesh Networks (WMNs) are considered for a plethora of complex applications, where different QoS specifications should be satisfied. In such applications, QoS issues concerning the delay and the reliability of data transmission are of utmost importance. In this paper, a distributed routing protocol for WMNs operating above 10 GHz to support services with distributed QoS is presented. As far as propagation is concerned, the major factor limiting the performance of millimetre wave radio systems is rain attenuation. The routing problem is formulated as a problem of linear programming, where the objective is to determine the path with minimum transmission delay while at the same time, satisfying a given set of constraints. Lagrangian Relaxation and dual decomposition are used to solve the problem in a distributed way. The proposed algorithm exhibits a low computational complexity, it is scalable and guarantees convergence to an optimal routing scheme. Its performance is verified through extended simulations employing an accurate spatial‐temporal channel model. Copyright © 2007 John Wiley & Sons, Ltd.

On the efficient and fast response for sensor deployment in sparse wireless sensor networks

Wireless sensor networks have recently become new techniques and popular research issues. A wireless sensor network consists of a large number of sensor nodes that have the capabilities of sensing, computing and wireless transmission. Wireless sensor networks (namely WSNs) assist people in working under dangerous environments, provide long-term target observations and track on moving objects. Consequently, WSNs decrease risk and increase efficiency. Although WSNs have been studied extensively, several problems should be addressed, such as sensor-deployment policy, data aggregation/fusion issue, and data transmission issue. An efficient sensor-deployment approach could decrease cost, minimize transmission delay and reduce time complexity. Most studies have proposed the probability-based sensor-deployment policies to monitor an overall area. However, not the entire network is interested to be sensed/monitored. Monitoring of an entire area brings several disadvantages: (1) high cost of placing large number of sensors, (2) long delay of data transmission, (3) slow response and (4) unnecessary data aggregation. Furthermore, previous works were lack of considering the difference between the sensing and the transmission radii, and then yield inaccurate analysis. This work thus proposes an efficient sensor placement approach (namely ESP) for a sparse interested area with considering of obstructers that block the data transmission and sensing signal. Additionally, the issue of different radii of sensing and transmission is analyzed in detail. Numerical results demonstrate that the proposed ESP approach requires the least number of sensor nodes under various network sizes and different number of obstacles. Simulation results indicate that the number of sensor nodes decreases when the sensing or transmission radius increases. The running time of ESP, O( K 2), is also analyzed, which is better than that of the probability-based approaches, O( N 2), where K is the number of interested grids and N is the number of grids.

Traffic characteristics of Go‐back‐N ARQ scheme with selective repeat in intra‐block

AbstractThis paper discusses the traffic characteristics of the Go‐back‐N (GBN)_SR scheme, in which the receiver returns the acknowledge signal blockwise and selective repeat is performed within the retransmission block. First the strict expression for the throughput and the strict expression for the average transmission delay of the blockwise bulk arrival model are derived. Then, the throughput of the GBN_SR scheme and the average transmission delay of the blockwise bulk arrival model are examined by numerical calculation. The average transmission delay of the packetwise bulk arrival model is investigated by simulation. It is shown that the throughput is improved with increasing block size, and that the average transmission delay can be minimized by using the optimal block size, depending on the average packet error rate and the block arrival rate. It is also shown for the packetwise bulk arrival model that there exists a block size which minimizes the average transmission delay, and that the minimum average transmission delay is smaller than in the blockwise bulk arrival model. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 86(3): 9–16, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ ecja.10052

ARCMA—adaptive request channel multiple access protocol for wireless ATM networks

AbstractWe propose a new multiple access protocol based on demand assignment. This protocol is designed to reduce contention in the request phase while minimizing transmission delay under various network (ATM) environments. Our protocol uses an adaptive scheme that changes under heavy traffic conditions, and also provides priority to certain delay‐sensitive traffic. Copyright © 2001 John Wiley & Sons, Ltd.

Triple Loop Networks with Minimal Transmission Delay

A multiloop network is a Cayley digraph of the additive group ℤm of integers modulo m generated by a set A of k ≥ 2 "steps". Because of their application to the computer network design, multiloop networks have been studied extensively. Given an integer d ≥ 2 and a real number r > 1, let m(d,3) be the maximum size of a triple loop network with transmission delay (diameter) less than or equal to d, and let m*(r,3) be the maximum size of a triple loop network with average transmission delay less than or equal to r. In this paper, the following lower bounds are proved: [Formula: see text] which improve earlier lower bounds by Jia and Aguiló, Fiol and Garcia.

Distributed loop network with minimum transmission delay

Distributed loop networks are networks with at least one ring structure. They are widely used in the design of local area networks, multimodule memory organizations, data alignments in parallel memory systems, and supercomputer architecture. In this paper, we give a systematic and unified method of solutions in the design and implementation of these networks. We show that doubly linked loop networks with transmission delay less than or equal to (1+ ε)√3 N can be constructed asymptotically for sufficiently large N, the number of nodes in the network. This is close to the optimal value within a number which is small as compared to N. We then give several infinite classes of values of N for which optimal doubly linked loop networks can be actually designed. The method is then generalized to obtain a new upper bound for possible transmission delays in multiply linked loop networks. Routing and rerouting algorithms are designed for the optimal loop networks.

Minimal diameter double‐loop networks. I. Large infinite optimal families

AbstractDouble‐loop networks G(n,h) (also known as circulants) are considered, where each node i in a loop of n nodes is also joined by chords to the nodes i ± h mod n. An integer n, a hop h, and a network G(n,h) are defined as optimal if the diameter D of G(n,h) equals the lower bound k when n is in R[k] = {2k2 − 2k + 2, …, 2k2 + 2k + 1}. n ∈ R[k], h, and G(n,h) are defined as suboptimal if D = k + 1. New infinite families of optimal networks are identified, along with corresponding optimal hops. For each k, those families contain O(√k) values of the 4k values of n in R[k]. Also, lower and upper bounds on optimal and suboptimal hops are given, along with a simple algorithm to compute those hops whenever they exist. It is conjectured that all values of n are either optimal or suboptimal. The optimal graphs G(n,h) are applicable in the design of ILLIAC‐type interconnection networks for parallel processing and of local area communication networks with minimal transmission delay.

Reliable circulant networks with minimum transmission delay

It is well known that maximum connectivity graphs play an important role in the design of reliable networks. The class of symmetric graphs called circulants is known to contain such maximum connectivity graphs. Although not all circulants have this maximum connectivity property, those that do have a great variation in their diameters. Since diameter is a measure of transmission delay, the minimum diameter, maximum connectivity circulant problem is considered here. Several results are given for the general case and a simple solution is derived for the connectivity four case.

Optimal Bandwidth Assignment on Up- and Downlinks of Satellite with Buffer Capacity

This paper considers a satellite communication system with the slotted ALOHA access mode where the satellite is assumed to have on-board regeneration ability and the finite buffer capacity for storing noncollided packets from the uplink. The system is analyzed with the downlink bandwidth restricted to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/L</tex> of the uplink bandwidth, and with the conventional slotted ALOHA system where <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">L = 1</tex> and the buffer size at the satellite is equal to zero. Maximum throughput and throughput-delay characteristics of this system are analytically obtained. The satellite is given an optimal buffer size to achieve maximum throughput and minimum packet transmission delay. It is shown that the constraints that lead to the downlink bandwidth being lower than the uplink bandwidth do not necessarily result in throughput penalties in a buffered satellite system. Furthermore, when the total bandwidth which can be divided between up- and downlinks is given, if two or three times that of the downlink is assigned to the uplink and if the satellite has buffer storage space only for a few packets, we show that maximum throughput of the system will be improved about 40 percent with little change in delay characteristics in comparison with that of the conventional slotted ALOHA system where the given total bandwidth is equally divided between up- and downlinks.