Delay In Multi-hop Wireless Networks Research Articles

Retraction Note to: Dynamic scheduling and congestion control for minimizing delay in multihop wireless networks

Retraction Note to: Dynamic scheduling and congestion control for minimizing delay in multihop wireless networks

RETRACTED ARTICLE: Dynamic scheduling and congestion control for minimizing delay in multihop wireless networks

RETRACTED ARTICLE: Dynamic scheduling and congestion control for minimizing delay in multihop wireless networks

Minimizing end-to-end delay in multi-hop wireless networks with optimized transmission scheduling

The problem of transmission scheduling in single hop and multi-hop wireless networks has been extensively studied. The focus has been on optimizing the efficiency of transmission parallelization, through a minimum-length schedule that meets a given set of traffic demands using the smallest possible number of time slots. Each time slot is associated with a set of transmissions that are compatible with each other according to the considered interference model. The minimum-length approach maximizes the resource reuse, but it does not ensure minimum end-to-end packet delay for multiple source-destination pairs, due to its inherent assumption of frame periodicity. In the paper we study the problem of transmission scheduling and routing aiming at minimizing the end-to-end delay under the signal-to-interference-and-noise-ratio (SINR) model for multi-hop networks. Two schemes are investigated. The first scheme departs from the conventional scheduling approach, by addressing explicitly end-to-end delay and removing the restriction of frame periodicity. The second scheme extends the first one by featuring cooperative forwarding and forward interference cancellation. We study the properties of the two schemes, and propose novel mixed-integer programming models and solution algorithms. Extensive results are provided to gain insights on how the schemes perform in end-to-end delay.

Nonasymptotic Multicast Throughput and Delay in Multihop Wireless Networks

Previous works on multicast capacity mainly focus on deriving asymptotic order results in large-scale wireless networks. While they can explore the general scaling laws of throughput capacity, it is also of great interest for practical concern to predict the exact achievable throughput in networks with an arbitrary finite number of nodes. In this paper, we investigate the nonasymptotic throughput and delay of multihop wireless networks for multicast applications wherein for each source node, $k$ nodes are randomly selected as receivers. It is challenging for the exact performance analysis since multicast transmission has a dynamic nature due to the following factors: 1) random distribution of nodes; 2) bursty traffic arrivals; and 3) different timescales for transient analysis. To tackle the problem, we propose an explicit analytical model and develop a multicast routing scheme, which accounts for these aspects. With our proposed model, we derive lower bound (LB) and upper bound (UB) on nonasymptotic multicast throughput and delay using stochastic network calculus. We show that the performance results hold for all timescales and network sizes and are strongly correlated to data burstiness and the number of receivers. While we investigate from a nonasymptotic point of view, our results can also cover the asymptotic scaling laws. Simulations are conducted to further verify the accuracy of the analytical bounds.

A Jackson network model and threshold policy for joint optimization of energy and delay in multi-hop wireless networks

Abstract This paper studies the joint optimization problem of energy and delay in a multi-hop wireless network. The optimization variables are the transmission rates, which are adjustable according to the packet queueing length in the buffer. The optimization goal is to minimize the energy consumption of energy-critical nodes and the packet transmission delay throughout the network. In this paper, we aim at understanding the well-known decentralized algorithms which are threshold based from a different research angle. By using a simplified network model, we show that we can adopt the semi-open Jackson network model and study this optimization problem in closed form. This simplified network model further allows us to establish some significant optimality properties. We prove that the system performance is monotonic with respect to (w.r.t.) the transmission rate. We also prove that the threshold-type policy is optimal, i.e., when the number of packets in the buffer is larger than a threshold, transmit with the maximal rate (power); otherwise, no transmission. With these optimality properties, we develop a heuristic algorithm to iteratively find the optimal threshold. Finally, we conduct some simulation experiments to demonstrate the main idea of this paper.

Cross-Layer Schemes for Reducing Delay in Multihop Wireless Networks

End-to-end delay is an important QoS metric in multihop wireless networks such as sensor networks and mesh networks. End-to-end delay is defined as the total time it takes for a single packet to reach the destination. It is a result of many factors including the length of the route and the interference level along the path. In this paper we address how to minimize end-to-end delay jointly through optimizing routing and link layer scheduling. We present two cross-layer schemes, a loosely coupled cross-layer scheme and a tightly coupled cross-layer scheme. In the loosely coupled cross-layer scheme, routing is computed first and then the information of routing is used for link layer scheduling; in the tightly coupled scheme, routing and link scheduling are solved in one optimization model. The two cross-layer schemes involve interference modeling in multihop wireless networks with omnidirectional antenna. A sufficient condition on conflict-free transmission is established, which can be transformed to polynomial-sized linear constraints, and a linear program based on the sufficient condition is developed. Through simulation, we show that the proposed routing and scheduling schemes can outperform their counterparts in each layer, and the integrated cross-layer schemes are superior to the combination of the existing routing and scheduling schemes.

Minimizing multiplayer interactive delay in multihop wireless networks

SUMMARYMinimizing the schedule frame length in spatial time division multiple access networks is essential in enhancing the performance of multiplayer interactive applications in multiple‐group multicasting environments. In this paper, the joint link scheduling and multiple‐group communication problem in such networks is referred to as a real‐time multiple‐group communication tree scheduling (RMGCTS) problem in which the objective is to minimize the total schedule frame length. It is shown that the RMGCTS problem can be represented as an integer linear programming problem. Two particular RMGCTS problems are considered, namely, back‐to‐back RMGCTS for applications with a receiving‐jitter constraint, and general RMGCTS for applications with a delay constraint. Two heuristic algorithms, designated as back‐to‐back scheduling and level‐by‐level scheduling, are proposed to provide efficient solutions of the back‐to‐back and general RMGCTS problems by maximizing the spatial reuse capability within each time slot, thereby minimizing the schedule frame length. The simulation results show that the proposed schemes yield an effective reduction in the length of the multicast schedule frame compared to that obtained from existing tree‐based or pure‐color scheduling algorithms. Copyright © 2011 John Wiley & Sons, Ltd.

Impact of node density on throughput and delay scaling in multi-hop wireless networks

This paper studies the impact of node density on the end-to-end throughput and delay in multi-hop wireless networks. In existing work, each packet is most assumed to be relayed through one cell at each hop and the hop progress is approximated by the square root of a cell area, which does not correspond to the actual hop progress in the real network. In this paper, we calculate the hop progress by taking into account the effect of node density (i.e., the number of nodes within the transmission range of each node), and obtain the required hop count for a multi-hop path. Based on the result, we further discuss the scaling relations between node density and throughput and delay in multi-hop wireless networks. The effects of power control on the scaling relations are also examined. The results show that the impact of node density on the throughput and delay scaling is significant. Specifically, with a larger node density, the required hop count is reduced, resulting in exponential growth of the throughput. However, larger node density incurs more contentions among neighboring nodes. Consequently, it causes linear degradation in throughput. With our model, this trade-off is readily observed.

Reduced Congestion Queuing: QoS Support for Optimizing Base Station Layout in Multihop Wireless Networks

A QoS support technique for easily minimizing delay in multihop wireless networks is proposed. Using a priority queue operation that reduces delays overall, the proposed technique, Reduced Congestion Queuing (RCQ), solves problems peculiar to multihops. By adding RCQ to a multihop system, base station or access point density and cost can be more effectively curtailed than by simply applying multihops to a cellular network or wireless LAN because RCQ expands the multihop service area. Due to its simplicity, the proposed technique can be used in a wide range of applications, including VoIP.