Average Network Throughput Research Articles

Cooperative multicasting based on superposition and layered coding

Cooperative diversity plays an important role in combating channel fading and increasing reliability of wireless communication links. The main purpose of cooperative diversity is to transmit the same data from multiple sources. Hence, there is no inherent capability in the cooperative diversity schemes to deal with scalable types of data, for example, scalable video coded signals. The authors introduce a two-phase cooperative multicast scheme based on superposition coding to transmit scalable video signals. The new scheme mixes the superposition with cooperative diversity, and chooses the right parameters in both schemes to enhance the system's multicast capability. This study also derives an exact closed-form expression of the average multicast group throughput in case of Rayleigh flat fading channel. The closed-form expression allows system designers to choose the correct cooperation and superposition parameters to satisfy the network operator needs. Simulations show that, in addition to the additional degrees of freedom resulting from using cooperation with superposition, the proposed scheme outperforms the conservative scheme and schemes solely exploiting cooperative relaying or superposition. Simulations show that the new scheme can increase the average network throughput more than four times compared to the conservative scheme.

Automated Re-Allocator of Replicas Over Mobile Ad Hoc Networks

In a Mobile Ad hoc Network (MANET), due to mobility, limited battery power and poor features of nodes, network partitioning and nodes disconnecting occur frequently. To improve data availability, database systems create multiple copies of each data object and allocate them on different nodes. This paper proposes Automated Re-allocator of Replicas Over MANET (ARROM), that addresses these issues. ARROM reduces the average response time of requests between clients and database servers by reallocating replicas frequently. In addition, ARROM increases the average throughput in the network. Our performance study indicates that ARROM improves average response time and average network throughput in MANET as compared to resent existing scheme.

Energy efficient management framework for multihop TDMA-based wireless networks

Green networking has recently been proposed to reduce energy cost as well as carbon footprint of computer networks. However, the application of green networking to multihop wireless networks has seldom been reported in the literature. This paper presents an energy-efficient framework for joint routing and link scheduling in multihop TDMA-based wireless networks. Our objective is to find an optimal tradeoff between the achieved network throughput and energy consumption. To do so, we first propose an Optimal approach, called Optimal Green Routing and Link Scheduling (O-GRLS), by formulating the problem as an integer linear program (ILP). As this problem is NP-Hard, we then propose a simple yet efficient heuristic algorithm based on Ant Colony, called AC-GRLS. Through extensive simulations, we show that both approaches can achieve significant gains in terms of energy consumption, flow acceptance ratio and achieved throughput, compared to the Shortest Path (SP) routing, and the Minimum link Residual Capacity (MRC) based routing. In particular, we show that the same performance as SP or MRC in terms of average network throughput can be attained with up to 20% energy saving. On the other hand, with the same energy cost, our approaches enhance the flow acceptance ratio by up to 35% in average. This leads to a throughput increase of approximately 50% and 52% compared to SP and MRC routing, respectively.

Optical Network Management and Its Performance Evaluation for Both Future Cost Planning and Triple Play Solutions

This paper has presented the wavelength division multiplexing technology is being extensively deployed on point to point links within transport networks in the Egypt. Our suggested Trans-Egypt Network which uses optical cross connects to route lightpaths through the network are referred to as wavelength routing networks. The average setup time, average link utilization, traffic load, blocking probability, network costs, and network throughput with triple play solutions and achievable link utilization for multi math routing in the presence and absence of wavelength conversions are the major interesting parameters in the design of network topology under different routing and wavelength assignment such as first fit, random, least used and most used in order to upgrade network performance and its transmission efficiency.

Topology-Transparent Broadcast Scheduling with Erasure Coding in Wireless Networks

Broadcasting is an important function in wireless networks. Ensuring broadcast efficiency and reliability with low communication overhead is challenging, especially with error-prone links. In this letter, we employ erasure coding together with topology-transparent scheduling as a coded transmission strategy in the MAC (Medium Access Control) layer rather than the physical layer to combat collisions and channel errors, implementing an efficient and reliable broadcast algorithm in wireless networks without introducing any additional communication overhead. We achieve the optimal frame structure that maximizes the average network throughput, and investigate the performance of our proposed algorithm in terms of the average network throughput and the packet failure probability. Simulation results show that our proposed algorithm with erasure coding outperforms other existing topology-transparent broadcast algorithms and the conventional TDMA dramatically.

Interference Alignment in a Poisson Field of MIMO Femtocells

The need for bandwidth and the incitation to reduce power consumption lead to the reduction of cell size in wireless networks. This allows reducing the distance between a user and the base station, thus increasing the capacity. A relatively inexpensive way of deploying small-cell networks is to use femtocells. However, the reduction in cell size causes problems for coordination and network deployment, especially due to the intra- and cross-tier interference. In this paper, we consider a two-tier multiple-input multiple-output (MIMO) network in the downlink, where a single macrocell base station with multiple transmit antennas coexists with multiple closed-access MIMO femtocells. With multiple receive antennas at both the macrocell and femtocell users, we propose an opportunistic interference alignment scheme to design the transmit and receive beamformers in order to mitigate intra- (or inter-) and cross-tier interference. Moreover, to reduce the number of macrocell and femtocell users coexisting in the same spectrum, we apply a random spectrum allocation on top of the opportunistic interference alignment. Using stochastic geometry, we analyze the proposed scheme in terms of the distribution of a received signal-to-interference-plus-noise ratio, spatial average capacity, network throughput, and energy efficiency. In the presence of imperfect channel state information, we further quantify the performance loss in spatial average capacity. Numerical results show the effectiveness of our proposed scheme in improving the performance of random MIMO femtocell networks.

New Metric for HWMP Protocol (NMH)

The IEEE 802.11s Wireless Mesh Networks (WMN) is a new multi -hop technology increasing the coverage of IEEE 802.11 Wireless Network and providing Internet access. Recently, many researchers proposed several metric routing protocols for wireless mesh networks(WMNs). Some metrics consider the interferences and other study the channel diversity of the distant links along the path between the source and the destination. In order to provide the best path between the source and the destination, this paper proposes a new routing metric named (NMH) New Metric for Hybrid Wireless Mesh Protocol(HWMP). NMH is based on two hop channel diversity and hop delay. The simulation results show that NMH out performs WCETT in terms of average network throughput, end -to-end delay and number of flows.

Fair data collection scheme in wireless sensor networks

To solve the slow congestion detection and rate convergence problems in the existing rate control based fair data collection schemes, a new fair data collection scheme is proposed, which is named the improved scheme with fairness or ISWF for short. In ISWF, a quick congestion detection method, which combines the queue length with traffic changes of a node, is used to solve the slow congestion detection problem, and a new solution, which adjusts the rate of sending data of a node by monitoring the channel utilization rate, is used to solve the slow convergence problem. At the same time, the probability selection method is used in ISWF to achieve the fairness of channel bandwidth utilization. Experiment and simulation results show that ISWF can effectively reduce the reaction time in detecting congestion and shorten the rate convergence process. Compared with the existing tree-based fair data collection schemes, ISWF can achieve better fairness in data collection and reduce the transmission delay effectively, and at the same time, it can increase the average network throughput by 9.1% or more.

Dynamic Multi-Path Service Provisioning under Differential Delay Constraint in Elastic Optical Networks

Optical orthogonal frequency-division multiplexing (O-OFDM) technology has the elastic feature of allocating spectrum resources based on subcarrier slots with bandwidths at a few GHz or even narrower. This feature enables us to utilize link capacity more efficiently by splitting a connection's traffic over multiple routing paths. In this paper, we propose a novel dynamic multi-path provisioning algorithm for O-OFDM based elastic optical networks. The algorithm tries to set up dynamic connections with single-path routing in a best-effort manner. When a connection cannot be served with a single routing path, the algorithm uses an auxiliary-graph based approach to calculate a multi-path provisioning scheme based on two parameters, i.e., the differential delay upper-bound and the bandwidth allocation granularity. Simulation results indicate that compared with several existing single-path provisioning algorithms, the proposed algorithm provides lower bandwidth blocking probability and achieves 10-18% improvement on average network throughput.

Performance Modeling of Broadcast Polling in IEEE 802.16 Networks with Finite-Buffered Subscriber Stations

In this paper, an approximated model is proposed to analyze the performance of the contention based services via broadcast polling in unsaturated IEEE 802.16 networks with channel errors. The main idea is that each subscriber station with buffer capacity K can be treated as a M/G/1/K queue with service time determined by the backoff process of broadcast polling. Using this model, the normalized network throughput and the distribution of the packet delay are derived. This proposed analytical model is useful for performance evaluation and optimization of best effort or contention-based non-real time polling services. Our simulator written in C++ verifies the accuracy of the proposed analytical model. Furthermore, we show that the model gives good approximations for network performance with a more realistic bursty arrival process at light load, while providing conservative performance measures at medium and high loads.

Joint Optimal Sensing Time and Power Allocation for Amplify-and-Forward Cognitive Relay Networks

In this letter, we investigate the joint optimization of sensing time and power allocation for amplify-and-forward cognitive relay networks. By jointly considering the sensing slot and the data transmission slot, the optimization problems are respectively formulated to maximize the average network throughput and minimize the approximate outage probability of secondary transmission under the average transmit power constraint of secondary users and the average interference power constraint of primary user. The optimal algorithms are developed to acquire the optimal sensing time and power allocation. Simulation results demonstrate that significant improvements in the average throughput and outage behavior are achieved through the joint optimization.

Sensing matrix setting schemes for cognitive networks and their performance analysis

Powerful spectrum decision schemes enable cognitive radios (CRs) to find transmission opportunities in spectral resources allocated exclusively to the primary users. One of the key effecting factors on the CR network throughput is the spectrum sensing sequence used by each secondary user (SU). In this study, SUs’ throughput maximisation through finding an appropriate sensing matrix (SM) is investigated. First, the average throughput of the CR network is evaluated for a given SM. Then, an optimisation problem based on the maximisation of the network throughput is formulated in order to find the optimal SM. As the optimum solution is very complicated, three novel suboptimal solutions are proposed for various cases including perfect and non-perfect sensing. Despite having less computational complexities as well as lower consumed energies, the proposed solutions perform quite well compared to the optimum solution. The structure and performance of the proposed SM setting schemes are discussed in detail and a set of illustrative numerical results is presented to validate their efficiencies.

Joint routing and channel assignment algorithms in cognitive wireless mesh networks

ABSTRACTMultiple channels can increase network capacity by transmitting traffic on different channels in an interference area. To resolve the channel interference problem in cognitive wireless mesh networks, first, a new channel assignment algorithm based on hierarchy interference model for the cognitive wireless mesh networks is proposed in this paper. Second, a distributed capacity and interference based channel assignment and routing algorithm is proposed. Third, an efficient channel diversity based channel allocation algorithm is proposed. The main purpose of this channel allocation algorithm is to maintain the channel diversity in the neighborhood channels. Fourth, a novel joint multi‐path routing and channel assignment algorithm based on path crossing is proposed. On the basis of simulations, results show that compared with the link‐based channel allocation algorithm in wireless multi‐channel networks, the new four algorithms have an obvious advantage in the performance of delay and throughput, and the performance of the joint multi‐path routing and channel assignment algorithm is the best. Lastly, a channel merging algorithm is also proposed in the channel constrained situation. Simulation results also show that, after the implementation of the channel merging algorithm, the network average throughput and delay performance have been further improved significantly. Copyright © 2012 John Wiley & Sons, Ltd.

Characterizing Decentralized Wireless Networks with Temporal Correlation in the Low Outage Regime

Communication in decentralized wireless networks is limited by interference. Because transmissions typically last for more than a single contention time slot, interference often exhibits a strong statistical dependence over time that results in temporally correlated communication performance. The temporal dependence in interference increases as user mobility decreases and/or the total transmission time increases. We propose a network model that spans the extremes of temporal independence to long-term temporal dependence. Using the proposed model, closed-form single hop communication performance metrics are derived that are asymptotically exact in the low outage regime. The primary contributions are (i) deriving the joint temporal statistics of network interference and showing that it follows a multivariate symmetric alpha stable distribution; (ii) utilizing the joint interference statistics to derive closed-form expressions for local delay, throughput outage probability, and average network throughput; and (iii) using the joint interference statistics to redefine and analyze the network transmission capacity that captures the throughput-delay-reliability tradeoffs in single hop transmissions. Simulation results verify the closed-form expressions derived in this paper and we demonstrate up to 2× gain in network throughput and reliability by optimizing certain parameters of medium access control layer protocol in view of the temporal correlations.

Network Coding Based Packets Queue Operation for Wireless Ad Hoc Networks

Wireless communication is a technology that simplify the daily life and to narrow the distance between people. Unfortunately throughput limitation of wireless networks is limiting the performance of wireless networks. In order to increase the throughput of the wireless network, network coding has been proposed to increase the throughput of network. Unlike conventional store-and-forward method, network coding is a method that intelligently combines packet from difference flow to reduce the transmissions while transfer the packets instead of just relay packets without doing any additional processing. Ad hoc on-demand distance vector routing protocol (AODV) will be used to discover route for packets from source to destination in wireless ad hoc networks. The simulation of wireless ad hoc network with and without network coding will be conducted in MATLAB. This paper introduces the development of simulation to illustrate the performance of network coding in wireless ad hoc network. The simulation will calculate the transmit packet time according to the size of the packet. Lastly, average network throughput performance between network coding and store-and-forward is shown and compared.

Dynamic Bandwidth Allocation with Adaptive Threshold in EPON

The Ethernet passive optical networks(EPON) are high-speed solutions to the bottleneck problem of the broadband access network.To provide efficient and fair utilization of the EPON upstream bandwidth and support QoS requirements of different traffic classes,a dynamic bandwidth allocation algorithm based on gate threshold is proposed.The algorithm decides the data-receiving rate of the ONU(optical network unit),according to the ONU data-sending response rate and the gate threshold.It then,implements three methods to adapt and adjust the gate threshold,and analyzes these methods' characteristic.Simulation experiments show the algorithm can decrease average packet delay and increase network throughput.

A Torus-Based Hierarchical Optical-Electronic Network-on-Chip for Multiprocessor System-on-Chip

Networks-on-chip (NoCs) are emerging as a key on-chip communication architecture for multiprocessor systems-on-chip (MPSoCs). Optical communication technologies are introduced to NoCs in order to empower ultra-high bandwidth with low power consumption. However, in existing optical NoCs, communication locality is poorly supported, and the importance of floorplanning is overlooked. These significantly limit the power efficiency and performance of optical NoCs. In this work, we address these issues and propose a torus-based hierarchical hybrid optical-electronic NoC, called THOE. THOE takes advantage of both electrical and optical routers and interconnects in a hierarchical manner. It employs several new techniques including floorplan optimization, an adaptive power control mechanism, low-latency control protocols, and hybrid optical-electrical routers with a low-power optical switching fabric. Both of the unfolded and folded torus topologies are explored for THOE. Based on a set of real MPSoC applications, we compared THOE with a typical torus-based optical NoC as well as a torus-based electronic NoC in 45nm on a 256-core MPSoC, using a SystemC-based cycle-accurate NoC simulator. Compared with the matched electronic torus-based NoC, THOE achieves 2.46X performance and 1.51X network switching capacity utilization, with 84% less energy consumption. Compared with the optical torus-based NoC, THOE achieves 4.71X performance and 3.05X network switching capacity utilization, while reducing 99% of energy consumption. Besides real MPSoC applications, a uniform traffic pattern is also used to show the average packet delay and network throughput of THOE. Regarding hardware cost, THOE reduces 75% of laser sources and half of optical receivers compared with the optical torus-based NoC.

Interference Statistics and Performance Analysis of MIMO Ad Hoc Networks in Binomial Fields

This paper investigates the interference statistics and system performance of a finite multiple-input-multiple-output (MIMO) ad hoc network. A finite network contains a finite number of nodes in a finite region. For such a network, the binomial point process, rather than the ubiquitously employed Poisson point process, is adopted to characterize the spatial node distribution. Reception techniques such as the maximal ratio combining (MRC) and zero forcing (ZF) are employed at the receiver, around which a guard zone is deployed. Either spatial multiplexing or antenna selection is employed at the transmitter side, depending on the availability of feedback. The moment generating functions of the aggregate interference power are first derived, based on which the moments of interference and the outage probability of a test link are obtained. It is shown that the full diversity provided by the channel can be achieved by single-stream transmission, including transmit antenna selection. A network performance measure, i.e., the average network throughput, is also analyzed. Simulations are provided to complement the analysis.

Reduced-Complexity Radio Architectures for Enhanced Receive Selection Combining in Multiuser Diversity Systems

Although antenna selection is a simple and efficient technique for enhancing the downlink performance of multiuser diversity systems, the large antenna interelement spacing required for achieving spatial diversity is prohibitive for user terminals due to size restrictions. In order to allay this problem, we propose miniaturized switched beam receiver designs assisted by low-cost passive reflectors. Unlike conventional spatial receive diversity systems, the proposed angular diversity architectures occupy a small volume whereas the antenna system properties are optimized by controlling the strong reactive fields present at small dimensions. The systems are designed for maximum antenna efficiency and low interbeam correlation, thus yieldingNpractically uncorrelated receive diversity branches. The simulation results show that the proposed enhanced diversity combining systems improve the average throughput of a multiuser network outperforming classical antenna selection especially for small user populations and compact user terminal size.

Resource allocation via sum‐rate maximization in the uplink of multi‐cell OFDMA networks

ABSTRACTIn this paper, we consider maximizing the sum rate in the uplink of a multi‐cell orthogonal frequency‐division multiple access network. The problem has a non‐convex combinatorial structure and is known to be NP‐hard. Because of the inherent complexity of implementing the optimal solution, firstly, we derive an upper bound (UB) and a lower bound (LB) to the optimal average network throughput. Moreover, we investigate the performance of a near‐optimal single cell resource allocation scheme in the presence of inter‐cell interference, which leads to another easily computable LB. We then develop a centralized sub‐optimal scheme that is composed of a geometric programming‐based power control phase in conjunction with an iterative subcarrier allocation phase. Although the scheme is computationally complex, it provides an effective benchmark for low complexity schemes even without the power control phase. Finally, we propose less complex centralized and distributed schemes that are well suited for practical scenarios. The computational complexity of all schemes is analyzed, and the performance is compared through simulations. Simulation results demonstrate that the proposed low complexity schemes can achieve comparable performance with that of the centralized sub‐optimal scheme in various scenarios. Moreover, comparisons with the UB and LB provide insight on the performance gap between the proposed schemes and the optimal solution. Copyright © 2011 John Wiley & Sons, Ltd.