Throughput In Multi-hop Wireless Networks Research Articles

Link Scheduling and End-to-End Throughput Optimization in Wireless Multi-Hop Networks

The goal of this work is to find appropriate link scheduling schemes to achieve satisfactory end-to-end throughput in wireless multi-hop networks. The algorithm of finding the best path status bitmap is proposed to solve the throughput problem. By analyzing path status, it is found that compressing the path state set can reduce the time complexity. According to this, we describe innovative methods to simplify scheduling of links for long path with large amount of data. Two typical link scheduling schemes with full-duplex radios are proposed, and end-to-end throughput boundary is worked out by analyzing the link capacity and the link active ratio in each scheme. Results illustrate that these schemes may improve end-to-end throughput in wireless multi-hop networks modestly.

Improving End-to-end Throughput in Multi-hop Wireless Networks with Cut-through Capability

Improving End-to-end Throughput in Multi-hop Wireless Networks with Cut-through Capability

End-to-End Throughput in Multihop Wireless Networks With Random Relay Deployment

This paper investigates the effect of relay randomness on the end-to-end throughput in multihop wireless networks using stochastic geometry. We model the nodes as Poisson Point Processes and calculate the spatial average of the throughput over all potential geometrical patterns of the nodes. More specifically, for problem tractability, we first start with the simple nearest neighbor (NN) routing protocol, and analyze the end-to-end throughput so as to obtain a performance benchmark. Next, note that the ideal equal-distance routing is generally not realizable due to the randomness in relay distribution, we propose a quasi-equal-distance (QED) routing protocol. We derive the range for the optimal hop distance, and select the relays to formulate a quasi-equidistant deployment. We analyze the end-to-end throughput both with and without intra-route resource reuse. Our analysis indicates that: (i) The throughput performance of the proposed QED routing can achieve a significant performance gain over that of the NN routing. As the relay intensity gets higher, the performance of QED routing converges to that of the equidistant routing. (ii) If the node intensity is a constant over the network, then intra-route resource reuse is always beneficial when the routing distance is sufficiently large. (iii) With randomly distributed relays, the communication distance can generally be extended. However, due to the uncertainty in relay distribution, long distance communication is generally not feasible with random relays. This implies that the existence of a reasonably defined infrastructure is critical in effective long distance communication. Our analysis is demonstrated through numerical examples.

Maximization of multicast periodic traffic throughput in multi-hop wireless networks with broadcast transmissions

Although a number of different medium access control (MAC) schemes are adopted for wireless multi-hop networks, time division multiple access (TDMA) approaches based on a periodic frame of time slots are the most common when very high efficiency is needed in terms of use of radio and energy resources. Efficient resource usage is typically based on parallel compatible transmissions from multiple nodes that guarantee interference control at the receivers. Optimization of transmission scheduling in multi-hop packet delivery from sources to destinations for a set of traffic relations can be achieved by minimizing the frame length where all necessary transmissions are organized in compatible sets and assigned to the time slots of the frame. When properly designed, the resulting TDMA scheme guarantees the delivery of packets for each traffic relation at a rate of up to one packet per frame duration regardless of the number of the packet transmissions (hops) necessary from source to destination, and thus it is particularly suitable for periodic traffic.While similar traffic maximization problems have been studied quite extensively for the case of unicast traffic, its multicast generalization (where each packet should be delivered from the source node to possibly multiple destination nodes) has not been elaborated so far. In this paper we present such a (non-trivial) generalization, namely a mathematical programming model based on the extension of the compatible set concept where the signal-to-noise and interference (SINR) ratio is guaranteed above a threshold at multiple receivers. We first propose an algorithm for solving the problem that generates compatible sets and schedules the frame by splitting the (predefined) multicast routing trees into one-hop transmissions. The high computational efficiency of the algorithm is proven through numerical results on large networks. Next, we enrich the model by adding multicast tree optimization, illustrating its efficiency numerically as well. Finally, we present possible extensions that consider packets of different lengths (requiring multiple slots for transmission), multiple modulation and coding schemes (MCS) requiring different SINR thresholds at the receivers, and packet delay minimization.

Impact of Full Duplex Scheduling on End-to-End Throughput in Multi-Hop Wireless Networks

There have been some rapid advances on the design of full duplex (FD) transceivers in recent years. Although the benefits of FD have been studied for single-hop wireless communications, its potential on throughput performance in a multi-hop wireless network remains unclear. As for multi-hop networks, a fundamental problem is to compute the achievable end-to-end throughput for one or multiple communication sessions. The goal of this paper is to offer some fundamental understanding on end-to-end throughput performance limits of FD in a multi-hop wireless network. We show that through a rigorous mathematical formulation, we can cast the multi-hop throughput performance problem into a formal optimization problem. Through numerical results, we show that in many cases, the end-to-end session throughput in a FD network can exceed 2x of that in a half duplex (HD) network. Our finding can be explained by the much larger design space for scheduling that is offered by removing HD constraints in throughput maximization problem. The results in this paper offer some new understandings on the potential benefits of FD for end-to-end session throughput in a multi-hop wireless network.

An energy-efficient multicast algorithm with maximum network throughput in multi-hop wireless networks

Energy consumption has become a main problem of sustainable development in communication networks and how to communicate with high energy efficiency is a significant topic that re- searchers and network operators commonly concern. In this paper, an energy-efficient multicast algorithm in multi-hop wireless networks is proposed aiming at new generation wireless communications. Traditional multi-hop wireless network design only considers either network efficiency or minimum energy consumption of networks, but rarely the maximum energy efficiency of networks. Different from previous methods, the paper targets maximizing energy efficiency of networks. In order to get optimal energy efficiency to build network multicast, our proposed method tries to maximize network throughput and minimize networks' energy consumption by exploiting network coding and sleeping scheme. Simulation results show that the proposed algorithm has better energy efficiency and performance improvements compared with existing methods.

Separation of Routing and Scheduling in Backpressure-Based Wireless Networks

Backpressure routing and scheduling, with its throughput-optimal operation guarantee, is a promising technique to improve throughput in wireless multihop networks. Although backpressure is conceptually viewed as layered, the decisions of routing and scheduling are made jointly, which imposes several challenges in practice. In this work, we present Diff-Max, an approach that separates routing and scheduling and has three strengths: 1) Diff-Max improves throughput significantly; 2) the separation of routing and scheduling makes practical implementation easier by minimizing cross-layer operations; i.e., routing is implemented in the network layer and scheduling is implemented in the link layer; and 3) the separation of routing and scheduling leads to modularity; i.e., routing and scheduling are independent modules in Diff-Max, and one can continue to operate even if the other does not. Our approach is grounded in a network utility maximization (NUM) formulation and its solution. Based on the structure of Diff-Max, we propose two practical schemes: Diff-subMax and wDiff-subMax. We demonstrate the benefits of our schemes through simulation in ns-2.

Spatial Reusability-Aware Routing in Multi-Hop Wireless Networks

In the problem of routing in multi-hop wireless networks, to achieve high end-to-end throughput, it is crucial to find the “best” path from the source node to the destination node. Although a large number of routing protocols have been proposed to find the path with minimum total transmission count/time for delivering a single packet, such transmission count/time minimizing protocols cannot be guaranteed to achieve maximum end-to-end throughput. In this paper, we argue that by carefully considering spatial reusability of the wireless communication media, we can tremendously improve the end-to-end throughput in multi-hop wireless networks. To support our argument, we propose spatial reusability-aware single-path routing (SASR) and anypath routing (SAAR) protocols, and compare them with existing single-path routing and anypath routing protocols, respectively. Our evaluation results show that our protocols significantly improve the end-to-end throughput compared with existing protocols. Specifically, for single-path routing, the median throughput gain is up to 60 percent, and for each source-destination pair, the throughput gain is as high as $5.3\times$ ; for anypath routing, the maximum per-flow throughput gain is 71.6 percent, while the median gain is up to 13.2 percent.

Scheduling in Multihop Wireless Networks With Zero-Forcing Precoding

Recently, multiple concurrent transmission techniques have been proposed for smartly exploiting interference to improve network throughput. This paper considers zero-forcing (ZF) precoding that allows two interfering links to concurrently transmit under certain situations. This paper focuses on identifying appropriate schedule schemes that efficiently utilize the ZF precoding opportunities to improve network throughput. With this motivation, we define novel link models to formulate our concerned problem. We also develop a distributed scheduling algorithm by using belief propagation. Finally, we conduct extensive simulation experiments to evaluate the efficiency of ZF in improving network throughput in multihop wireless networks. Our simulations confirm that intelligently utilizing ZF in multihop networks is very effective in improving throughput.

On bridging theory and practice of inter-session network coding for CSMA/CA based wireless multi-hop networks

Inter-session network coding is well known for its ability to spectral efficiency and end-to-end throughput in wireless multi-hop networks by up to four fold on some scenarios compared to standard routing. However, a variety of inter-session network coding implementations have consistently shown a decrease in throughput when operating at high traffic loads and significantly below the values expected theoretically. While still being superior to forwarding, this discrepancy between past analytical studies and real measurement results requires further understanding to realize inter-session network coding’s full potential in practice. This paper presents mathematical analysis for two of the key sources for this discrepancy, namely, long- and short-term channel asymmetries. We use this knowledge to develop, yet effective algorithm to cope with these asymmetries and bolster network coding’s performance in real systems. Our algorithm and other alternative algorithms have been implemented in a hardware platform that uses a CSMA/CA based medium access control (MAC) protocol. Performance evaluation is carried out via an extensive measurement campaign with node deployments in different testing environments, channel conditions, and active devices in the network with the equivalent to more than a month of continuous testing. Based on the measurement results, we demonstrate that our algorithm is capable of closing the gap to theoretically expected results despite being influenced by real world channel conditions while maintaining fairness to other network devices at the MAC level.

Distributed Throughput Maximization in Wireless Networks Using the Stability Region

In this paper, a game-theoretical framework for the design of distributed algorithms that control the transmission range (TR) of nodes in order to maximize throughput in Wireless Multihop Networks (WMN) is proposed. It is based on the stability region of the link-scheduling policy adopted for the network. The stability region is defined as the set of input-packet rates under which the queues in the network are stable (i.e., positive recurrent). The goal of the TR-control algorithms is to adapt the stability region to a given set of end-to-end flows. In the algorithms, the flows control distributively the nodes' TRs using the stability region in order to enable higher end-to-end packet rates while guaranteeing stability. In order to demonstrate how the algorithms can be designed using the proposed game-theoretical framework, a new TR-control algorithm for IEEE-802.16 WMNs is developed. Its convergence is demonstrated, and a performance bound is calculated. Finally, simulation results show that the algorithm is able to find the optimal TRs more effectively. The TRs achieve throughput levels that are at least 90 percent of the optimal throughput for 72 percent of the simulated scenarios, whereas the classic approach of spatial-reuse maximization does this for 62 percent of the scenarios.

Delay-Guaranteed Cross-Layer Scheduling in Multihop Wireless Networks

In this paper, we propose a cross-layer scheduling algorithm that achieves a throughput “ ε-close” to the optimal throughput in multihop wireless networks with a tradeoff of O([1/(ε)]) in average end-to-end delay guarantees. The algorithm guarantees finite buffer sizes and aims to solve a joint congestion control, routing, and scheduling problem in a multihop wireless network while satisfying per-flow average end-to-end delay constraints and minimum data rate requirements. This problem has been solved for both backlogged as well as arbitrary arrival rate systems. Moreover, we discuss the design of a class of low-complexity suboptimal algorithms, effects of delayed feedback on the optimal algorithm, and extensions of the proposed algorithm to different interference models with arbitrary link capacities.

Foreword by Guest Editors for the Special Issue on the 2012 ICUFN Conference

Welcome to this special issue of Wireless Personal Communications, which has taken the important role to keep up with the new technology evolution and enhancement in theoretical, engineering, and experimental aspects of radio communications, voice, data, images, and multimedia. This special issue constitutes a selection of best papers from the 2012 ICUFN (International Conference on Ubiquitous Future Networks) Conference. All these papers have been extended and reviewed again by 3 independent reviewers. ICUFN is an annual international conference (www.icufn.org) co-sponsored by IEEE Communications Society and organized by the KICS (Korean Information Communications Society). The first paper is entitled “Software-based Management for Ethernet Networks“. It presents a solution for this use case to integrate quality of service futures for the communication by a middleware based approach. The proposed mechanism in this paper discusses possible design improvements of this solution and presents the recent Ethernet standards that could help to solve this problem in an alternative way. The second paper entitled “Distributed Transmit Power Control for Maximizing Endto-End Throughput in Wireless Multi-hop Networks”. In a multi-hop link, the end-to-end throughput between a source and destination is restricted by the lowest link rate, so the maxmin fair allocation on the link rates is an optimal strategy to maximize. This paper proposes a transmit power control (TPC) algorithm that decides the transmit power of multi-hop nodes to equalize all link rates. The third paper entitled “An Architecture for Service Quality Management Using Cooperative Communications” proposes an architecture for application quality management and a detailed mechanism to maintain the desired multimedia application quality using the coop-

Distributed Transmit Power Control for Maximizing End-to-End Throughput in Wireless Multi-hop Networks

Wireless multi-hop networks have a solidarity property, in which each multi-hop link interferes mutually and so an increase in one link's rate results in a decrease of the other links' rate. In a multi-hop link, the end-to-end throughput between a source and destination is restricted by the lowest link rate, so the max-min fair allocation on the link rates is an optimal strategy to maximize the end-to-end throughput. In this paper, we verify that if the wireless links have a solidarity property, the max-min fair allocation has all link rates equal, so we propose a transmit power control (TPC) algorithm that decides the transmit power of multi-hop nodes to equalize all link rates. The proposed algorithm operates in a distributed manner, where each node averages the recognized link rates around itself, allocates its transmit power to achieve this average rate, and iterates this operation until all link rates become equal. Intensive simulation shows that the proposed TPC algorithm enables all link rates to converge on the same value, and thus maximizes the multi-hop end-to-end throughput while decreasing the power consumption of multi-hop nodes.

Optimal Routing and Scheduling in Multihop Wireless Renewable Energy Networks

We design routing and scheduling policies that optimize network throughput in multi-hop wireless networks where nodes are powered by renewable energy sources. The policies that we propose deliver maximum throughput, and yet do not require explicit knowledge of the statistics of the energy harvesting or the traffic generation processes. We consider both the cases of infinite and finite energy storage capacity at nodes. The results in the latter case provide bounds on the capacity of the energy storage devices at the individual nodes that is minimally required for obtaining maximum throughput.

Link Scheduling for Exploiting Spatial Reuse in Multihop MIMO Networks

Multiple-Input-Multiple-Output (MIMO) has great potential for enhancing the throughput of multihop wireless networks via spatial multiplexing or spatial reuse. Spatial reuse with Stream Control (SC) provides a considerable improvement of the network throughput over spatial multiplexing. The gain of spatial reuse, however, is still not fully exploited. There exist large numbers of additional data streams, which could be transmitted concurrently with those data streams scheduled by stream control at certain time slots and vicinities. In this paper, we address the issue of MIMO link scheduling to maximize the gain of spatial reuse and thus network throughput. We propose a Receiver-Oriented Interference Suppression model (ROIS), based on which we design both centralized and distributed link scheduling algorithms to fully exploit the gain of spatial reuse in multihop MIMO networks. Further, we address the traffic-aware link scheduling problem by injecting nonuniform traffic load into the network. Through theoretical analysis and comprehensive performance evaluation, we achieve the following results: 1) link scheduling based on ROIS achieves significant higher network throughput than that based on stream control, with any interference range, number of antennas, and average hop length of data flows. 2) The traffic-aware scheduling is enticingly complementary to the link scheduling based on ROIS model. Accordingly, the two scheduling schemes can be combined to further enhance the network throughput.

DSS: Distributed SINR-Based Scheduling Algorithm for Multihop Wireless Networks

The problem of developing distributed scheduling algorithms for high throughput in multihop wireless networks has been extensively studied in recent years. The design of a distributed low-complexity scheduling algorithm becomes even more challenging when taking into account a physical interference model, which requires the SINR at a receiver to be checked when making scheduling decisions. To do so, we need to check whether a transmission failure is caused by interference due to simultaneous transmissions from distant nodes. In this paper, we propose a scheduling algorithm under a physical interference model, which is amenable to distributed implementation with 802.11 CSMA technologies. The proposed scheduling algorithm is shown to achieve throughput optimality. We present two variations of the algorithm to enhance the delay performance and to reduce the control overhead, respectively, while retaining throughput optimality.

Routing and transmission scheduling for minimizing broadcast delay in multirate wireless mesh networks using directional antennas

Using directional antennas to reduce interference and improve throughput in multihop wireless networks has attracted much attention from the research community in recent years. In this paper, we consider the issue of minimum delay broadcast in multirate wireless mesh networks using directional antennas. We are given a set of mesh routers equipped with directional antennas, one of which is the gateway node and the source of the broadcast. Our objective is to minimize the total transmission delay for all the other nodes to receive a broadcast packet from the source, by determining the set of relay nodes and computing the number and orientations of beams formed by each relay node. We propose a heuristic solution with two steps. Firstly, we construct a broadcast routing tree by defining a new routing metric to select the relay nodes and compute the optimal antenna beams for each relay node. Then, we use a greedy method to make scheduling of concurrent transmissions without causing beam interference. Extensive simulations have demonstrated that our proposed method can reduce the broadcast delay significantly compared with the methods using omnidirectional antennas and single-rate transmission. In addition, the results also show that our method performs better than the method with fixed antenna beams. Copyright © 2012 John Wiley & Sons, Ltd.

Competitive throughput in multi-hop wireless networks despite adaptive jamming

This article presents a simple local medium access control protocol, called Jade, for multi-hop wireless networks with a single channel that is provably robust against adaptive adversarial jamming. The wireless network is modeled as a unit disk graph on a set of nodes distributed arbitrarily in the plane. In addition to these nodes, there are adversarial jammers that know the protocol and its entire history and that are allowed to jam the wireless channel at any node for an arbitrary $$(1-\epsilon )$$ -fraction of the time steps, where $$0<\epsilon <1$$ is an arbitrary constant. We assume that nodes can perform collision detection (unless they are transmitting themselves), but that they cannot distinguish between jammed transmissions and collisions of regular messages. Nevertheless, we show that Jade achieves an asymptotically optimal throughput by efficiently exploiting the unpredictable time periods in which the medium is available.

Distributed Transmit Power Control for Optimal End-to-End Throughput in Wireless Multihop Networks

In this paper, we propose a distributed transmit power control algorithm for optimal end-to-end throughput in wireless multihop networks. Considering a solidarity property of link rates consisting of a multihop link and the fact that the multihop end-to-end throughput is determined by the minimum link rate, the proposed scheme controls the transmit power to make all link rates be equal and so maximizes the end-to-end throughput of multihop link. In addition, in the proposed scheme the transmit node calculates its transmit power autonomously in a distributed manner just through the information sharing with its neighbor nodes and so decreases the information sharing overhead. Simulation results show that the proposed scheme achieves significant improvements in terms of end-to-end throughput and power consumption compared with the conventional maximum equal power allocation scheme.