Delay performance of a selective-repeat ARQ scheme with a Markovian error channel

Based on highly reliable data transmission, we previously proposed a Go‐Back‐N ARQ scheme with selective repeat in intra‐block, where the receiver returns the acknowledge signal in the unit of a block composed of multiple frames, with the aim of reducing the network traffic and the objective of effectively processing the frames. This paper considers the traffic characteristics when the number of block retransmissions in a Go‐Back‐N ARQ scheme with selective repeat in intra‐block is limited. In this scheme, blocks composed of multiple frames which contain information with some correlation as in images are transmitted. If the retransmission of a block reaches the preset limit, the receiver accepts that block even if erroneous frames are included, and the errors are processed as noise or distortion. Therefore, an upper bound can be set for the time elapsed from the start to the end of the block transmission. We theoretically analyze the system considered and derive the throughput, the average transmission delay of a block, and the average transmission delay with the condition of the number of transmissions. The traffic characteristics are investigated from numerical examples using analytical results. We show that the throughput performance and average transmission delay performance are improved by limiting the number of retransmissions. © 2006 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 90(3): 64–73, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20311

Research into a transport protocol for high-speed networks is one of the most progressive areas in the field of computer communications. In high-speed networks using optical fiber as a transmission medium that gives the bandwidth from a hundred Mbits/s to Gbits/s, the roundtrip (propagation) delay and bandwidth product becomes large. It is well known that for an increase in this product, the throughput performance of the conventional error control procedures such as the go-back-N-based-ARQ scheme does degrade significantly. Therefore, a new protocol based on a selective-repeat ARQ scheme must be developed. The authors propose the stop-and-selective repeat (SSR) ARQ protocol and analyze the throughput performance of it. The throughput formula is exactly derived in terms of the roundtrip delay, the frame error rate, and the window size of from one to two roundtrip delays. The window size needed to offer the adequate throughput greater than 95% is shown.

We present in this paper the analytical evaluation of a simple mechanism to reduce the average transmission delay of master stations in a network based on the Distributed Queuing MAC protocol for Ad hoc Networks (DQMAN). When DQMAN is executed, the network is self-organized into dynamic and spontaneous master-slave clusters. Within each cluster, a highperformance MAC protocol based on a tree-splitting collision resolution algorithm which uses access minislots is executed. By allowing temporary master stations to avoid contention to get access to the channel, their average packet transmission delay can be effectively reduced compared to that of slaves. This technique provides thus master stations with higher access priority to the channel and, indeed, could be used in any MAC protocol based on access minislots to provide a subset of users with higher priority.

In this article, we address the goal of achieving performance gains under heavy-load and fast fading conditions. CoopMACI protocol proposed in Proceedings of the IEEE International Conference on Communications (ICC), Seoul, Korea, picks either direct path or relay path based on rate comparison to enhance average throughput and delay performances. However, CoopMACI performance deteriorates under fading conditions because of lower direct path or relay path reliability compared to UtdMAC (Agarwal et al. LNCS, 4479, 415-426, 2007). UtdMAC was shown to perform better than CoopMACI in terms of average throughput and delay performances because of improved transmission reliability provided by the backup relay path. Although better than CoopMACI, UtdMAC does not fully benefit from higher throughput relay path (compared to the direct path), since it uses relay path only as a secondary backup path. In this article, we develop a cooperative MAC protocol (termed as instantaneous relay-based cooperative MAC--IrcMAC) that uses channel coherence time and estimates signal-to-noise ratio (SNR) of source-to-relay, relay-to-destination, and source-to-destination links, to reliably choose between relay path or direct path for enhanced throughput and delay performances. Unique handshaking is used to estimate SNR and single bit feedbacks resolve contentions among relay nodes, which further provides source node with rate (based on SNR) information on source-to-destination, source-to-relay, and relay-to-destination links. Simulation results clearly show that IrcMAC significantly outperforms the existing CoopMACI and the UtdMAC protocols in wireless ad hoc network. Results show average throughput improvements of 41% and 64% and average delay improvementd of 98.5% and 99.7% compared with UtdMAC and CoopMACI, respectively.

Device-to-device (D2D) communications combined with Heterogeneous networks (Hetnets) has attracted growing interest. Indeed, Hetnets deploy small-cells within macro-cells in order to offload traffic and improve the overall network coverage and capacity. Whereas, D2D promotes the use of communications between users for content delivery without going through the small or macro bases stations. Hence, it reduces communication delays and improves the spectral efficiency. In this context, we aim in this paper at reducing the average transmission delay, defined as the average sum delays of contents transmission to satisfy users’ requests in a macro-cell, by jointly optimizing caching placement and channel resource allocation, in cache-enabled Hetnet with D2D assistance. At first, a lower-bound expression of the average transmission delay is derived. Then, the optimization problem is formulated. Afterwards, we propose a sub-optimal random search algorithm and a low-complexity greedy algorithm that solve the problem. Finally, numerical results illustrate the performances of the proposed algorithms.

Underwater Wireless Sensor Network, often known as UWSN, is an appealing research zone because of the mysterious aspect of the ocean. A network of sensor nodes and vehicles that work together as part of the UWSN to collect information and carry out activities in collaboration. Because of the sensor nodes and the limited battery capacity, it is essential for UWSN to have an efficient network. The significant delay in propagation, network dynamics, and probability of error all influence underwater communication, making it difficult to exchange or update sensor nodes. This article put up the idea of a Grid-oriented underwater wireless sensor network (GO-UWSN) and carried out an analysis based on the criteria of energy consumption, utilization, average transmission delay, average jitter, average path loss and average E- 2- E delay in various modes.

Automakers have been pushing harder for the development of a safety-critical bus for the past years since there are many advantages of x-by-wire systems including steer-by-wire, brake-by-wire and throttle-by-wire. Such systems allow automakers to eliminate heavy hydraulic actuators and they offer the possibility of creating smarter and more efficient components that can be connected to a network bus. However, automakers and vendors know that a reliable, fault-tolerant bus is needed for such applications. Controller Area Network (CAN) buses, which are commonly used for powertrain and other automotive controls, are not considered reliable enough for drive-by-wire. The problem with CAN is that it is only event-based, so there is always a possibility that a message won't get through. For important applications, time-triggered architectures are needed because as time goes on, a slot for important messages is always assigned. In this paper, the performance evaluations of CAN, TTP and Byteflight are presented to explain which aspects are different and how the system should be designed for these protocols for x-by-wire systems. For evaluations, the simulation models were developed by using a discrete event simulation language, SIMAN. Based on these models numerous experiments were conducted for the comparable factors such as the probability of transmission failure, the average transmission delay and the maximum transmission delay. From the performance evaluation results, we can conclude that TTP exhibits a very stable performance over an extended traffic load while it lacks the flexibility for system changes. In addition, CAN and Byteflight show very good performance under low traffic while the performance deteriorates very fast as traffic exceeds a certain threshold.

Considering the time-averaged behavior of a metro elastic optical network, we develop a joint procedure for resource allocation and traffic shaping to exploit the inherent service diversity among the requests for power-efficient network operation. To support the quality of service diversity, we consider minimum transmission rate, average transmission rate, maximum burst size, and average transmission delay as the adjustable parameters of a general service profile. The work evolves from a stochastic optimization problem, which minimizes the power consumption subject to stability, physical, and service constraints. The optimal solution of the problem is obtained using a complex dynamic programming method. To provide a near-optimal fast-achievable solution, we propose a sequential heuristic with a scalable and causal software implementation, according to the basic Lyapunov iterations of an integer linear program. The heuristic method has a negligible optimality gap and a considerably shorter runtime compared to the optimal dynamic programming, and reduces the consumed power by 72% for an offered traffic with a unit variation coefficient. The adjustable trade-offs of the proposed scheme offer a typical 10% power saving for an acceptable amount of excess transmission delay or drop rate.

Mitigating the effects of head-of-line blocking (HoLB) was one of the major reasons the IETF SIGTRAN working group developed SCTP, a new transport protocol for PSTN signaling traffic, in the first place. However, studies of the impact of HoLB blocking on TCP and SCTP have given ambiguous results as to whether HoLB has, in fact, any significantly deteriorating effect on transmission delay. To this end, we have carried out a detailed experimental study on the quantitative effects of HoLB. Our study suggests that although HoLB could indeed incur a substantial delay penalty on a small fraction of the messages in an SCTP session, it has only a marginal impact on the average end-to-end transmission delay. We only observed improvements in the range of O% to 18% in average message transmission delay of using unordered delivery as compared to ordered delivery. Furthermore, there was a large variability in between different test runs, which often made the impact of HoLB statistically insignificant

The effects of transmission delay and channel errors on the performance of a distributed fusion system is studied. At a given time instant, the decisions from some sensors may not be available at the fusion center due to the transmission delays. Assuming that the fusion center has to make a decision based on the data from the rest of the sensors, provided that at least one peripheral decision has been received, it is shown that the optimal decision rule that maximizes the probability of detection for fixed probability of false alarm at the fusion center is the Neyman-Pearson test at the fusion center and the sensors as well. Furthermore, it is shown that, in the case of noisy channels, the decision made by each sensor depends on the reliability of the corresponding transmission channel. Moreover, the probability of false alarm at the fusion is restricted by the channel errors. For a given decision rule, the probability of any channel being in error must be kept at a certain level in order to achieve a desired probability of false alarm at the fusion. A suboptimal, but very near-to-optimal, computationally efficient algorithm is developed to solve for the sensor and fusion thresholds sequentially. Numerical results are provided to demonstrate the closeness of the solutions obtained by the suboptimal algorithm to the optimal solutions.

HEER – A delay-aware and energy-efficient routing protocol for wireless sensor networks

In this paper, we study packet transmission scheduling for a network with bidirectional relaying links, where the relay station can use network coding to combine packets to multiple receivers and opportunistically decide the number of packets to be combined in each transmission. Two cases are considered, depending on whether nodes are allowed to overhear transmissions of each other. A constrained Markov decision process is first formulated with an objective to minimize the average delay of packet transmissions, subject to the maximum and average transmission power limits of the relay node. The complexity for solving the constrained Markov decision process (MDP) is prohibitively high, although the computational complexity for the no‐overhearing case can be greatly reduced. Heuristic schemes are then proposed, one applies to the general case, and another applies to only the no‐overhearing case. Numerical results demonstrate that the heuristic schemes can achieve close‐to‐optimum average packet transmission delay, and furthermore, the second scheme achieves lower maximum delay while keeping the same average packet transmission delay and relay node power consumption as the first one. Copyright © 2015 John Wiley & Sons, Ltd.

We investigate the packet-level scheduling for the downlink of multiple-input multiple-output (MIMO) multi-user systems using beamforming. We consider the traffic arrival process and different packet lengths. We tackle low-complex practical implementation that provides low average packet transmission delay and bit error rates (BER) to users. We propose a work-conserving scheduling scheme that considers different users guarantees (heterogeneous users). We implement and compare different MIMO schedulers at the packet level. Simulations show the low average packet transmission delay and bit error rate of our proposed scheduler.

This paper proposes a delay-aware resource provisioning policy for virtualized wireless networks (VWNs) to minimize the total average transmit power while holding the minimum required average rate of each slice and maximum average packet transmission delay for each user. The proposed cross-layer optimization problem is inherently non-convex and has high computational complexity. To develop an efficient solution, we first transform cross-layer dependent constraints into physical layer dependent ones. Afterwards, we apply different convexification techniques based on variable transformations and relaxations, and propose an iterative algorithm to reach the optimal solution. Simulation results illustrate the effects of the required average packet transmission delay and minimum average slice rate on the total transmission power in VWN.

The proposed development of Sibu Central hinges on the fact that it attracts high number of visitors from all over Sarawak. The development of Sibu Central would definitely improve the surrounding areas in future as Sibu Central will be one of the landmarks for Sibu. This development therefore will automatically generate more road traffic which will affect the performance of the existing road. The performance of the existing road was evaluated by two signalized intersections surrounding the proposed development of Sibu Central. It was carried out in order to determine the current traffic volume data, upon the completion of Sibu Central and 5 years after the development was completed. The road performance of Intersection 1 and Intersection 2 was analysed by using Sidra software. It was found that the existing road was still within the satisfactory performance, as the Level of Service (LOS) was in the range of LOS A until LOS D. This was due to the current traffic volume that was still under the capacity of the existing road which also influenced the satisfactory result for Volume by Capacity (V/C) ratio, average delay and queue length of all directions in Intersection 1 and Intersection 2. This result will not be adequate as the capacity of the road still remains unchanged due to the fact that the traffic volume keeps on increasing every year. The deterioration of the existing road in Intersection 1 and Intersection 2 was established in this study based on the performance of LOS, V/C ratio, average delay and queue length.