Performance Of Heterogeneous Networks Research Articles

Estimating Performance of Mobile Services from Comparative Output-Input Analysis of End-to-End Throughput

Mobile devices with ever-increasing functionality and the ubiquitous availability of wireless communication networks are driving forces behind innovative mobile applications enriching our daily life. One of the performance measures for a successful application deployment is the ability to support application-data flows by heterogeneous networks within certain delay boundaries. However, the quantitative impact of this measure is unknown and practically infeasible to determine at real time due to the mobile device resource constraints. We research practical methods for measurement-based performance evaluation of heterogeneous data communication networks that support mobile application-data flows. We apply the lightweight Comparative Output-Input Analysis (COIA) method estimating an additional delay based on an observation interval of interest (e.g., 1 second) induced on the flow. An additional delay is the amount of delay that exceeds nonavoidable, minimal end-to-end delay caused by the networks propagation, serialization, and transmission. We propose five COIA methods to estimate additional delay, and we validate their accuracy with measurements obtained from the existing healthcare and multimedia streaming applications. Despite their simplicity, our methods prove to be accurate in relation to an observation interval of interest, and robust under a variety of network conditions. The methods offer novel insights into application-data delays with regards to the performance of heterogeneous data communication networks.

Optimal Fractional Frequency Reuse and Power Control in the Heterogeneous Wireless Networks

Heterogeneous wireless networks have emerged as a new paradigm to meet the fast growing wireless network capacity and coverage demands. Due to the co-deployment of high power and low power nodes in the same network using the same spectrum, more advanced interference coordination and radio resource management schemes are required than in the traditional cellular network in order to achieve a high network capacity and good user experience. In this paper, we propose an optimal fractional frequency reuse and power control scheme that can effectively coordinate the interference among high power and low power nodes. The scheme can be optimized to maximize the sum of the long term log-scale throughput among all the user equipments (UEs). Towards that end, the Lagrange dual function is first derived for the proposed optimization problem. Gradient descent method is then used to search the optimal solution for the convex dual problem. Due to the strong duality condition, the optimal solution for the dual problem is also the optimal solution for the primal problem. Simulation results show that the proposed scheme can greatly improve the wireless heterogeneous network performance on system capacity and user experience.

이기종 셀룰러 네트워크에서의 상향 링크 셀 접속 기법

단일 셀룰러 네트워크에는 같은 종류의 기지국만 존재하기 때문에 가장 가까운 기지국에 접속하는 하향 링크 수신 신호 기준 셀 접속이 상향 링크의 경우에도 최적의 셀 접속 방식이었다. 그러나 이기종 셀룰러 네트워크에서는 서로 다른 계층의 기지국의 하향 링크 수신 신호 차이와 상향 링크 수신 신호 차이가 다르기 때문에, 상향 링크 수신 신호의 경우 하향 링크 기반 셀 접속은 더 이상 최적의 셀 접속이 될 수 없다. 이에 본 논문에서는 이기종 셀룰러 네트워크에서 상향 링크 기준 셀 접속 기법에 대해 제안하고 상향 링크 성능을 효과적으로 볼 수 있는 성능 메트릭 (performance metric)을 제안한다. 이 성능 메트릭을 통하여 상향 링크 기준 셀 접속을 통해 아웃티지확률 (outage probability), 지연 제한 아웃티지 확률 (delay constraint outage probability), 지연 제한 아웃티지 용량 (delay constraint outage capacity) 측면에서 성능 향상을 보이고 상향 링크 기준 셀 접속의 필요성을 논의한다. In conventional single-tier networks, downlink based association is the best association scheme for the uplink association because all macro base stations have the same physical specification. However, in uplink heterogeneous cellular networks, a downlink based cell association cannot be the best for uplink any more because of the difference of physical specification between the different base station. In this paper, we will propose a uplink based cell association scheme, and devise performance metric for describing a uplink performance in heterogeneous cellular networks. Then, we will discuss the necessity of the uplink based association by observing outage probability, delay constraint outage probability, delay constraint outage capacity.

이기종 셀룰러 네트워크에서 펨토셀 성능향상을 위한 상향링크 간섭 회피 기법

This paper proposes a cross-tier interference avoidance scheme to improve femtocell performance in single frequency heterogeneous cellular networks (SFHCN). The scheduled macrocell users located close femtocell base stations cause serious interference to those femtocells so that the performance of femtocell is dramatically deteriorated. To solve this problem, this paper proposes an interference avoidance scheme by reversing the uplink and downlink frames of such femtocells. After reversing the uplink and downlink frames, femtocell base station relays the macrocell user data as well as transmitting its own data. In the 1st relaying link, femtocell and macrocell users transmit their data respectively divided uplink frames and in the 2nd relaying link, femtocell base station transmit macrocell and femtocell data using a simultaneously superposition coding scheme. Computer simulation results confirm performance improvement of proposed scheme.

Design and analysis of heterogeneous nanoscale on-chip communication networks

With a continuing downscaling of the physical feature sizes, an increase in complexity and the number of on-chip devices, and an increase in their heterogeneity, the traditional on-chip communication infrastructure needs to be revisited. It has previously been shown that multi-hop communication suffers from high latency and power consumption and that networks with long-range, high-bandwidth, and low power communication links significantly improve the system performance. Yet, it is an open problem what level of heterogeneity and what link type characteristics represent an optimum for on-chip communication networks. In this paper we design and analyze optimal heterogeneous networks by considering different cost and performance trade-offs in a technology-agnostic framework. We show that there is an optimal number of different link types for each set of constraints and that the heterogeneous network performance allows for a higher throughput at a lower cost compared to 2D regular mesh and homogeneous networks. From our results it follows that the link types available with current technology are non-optimal in a heterogeneous setup. We show that the main results are robust against certain model assumptions. In addition, the proposed heterogeneous networks scale up significantly better in terms of both cost and performance. The results are relevant for the design of emerging nanoscale communication fabrics and will help to drive the development of new technology.

Enhanced performance of heterogeneous networks through full-duplex relaying

In this article, we focus on the uplink of a heterogeneous network composed of a macrocell and an underlaid femtocell. We address the problem of the interference caused by the macro user (MU) on the femtocell [femto base station (FBS) and users]. The femtocell is composed of an user, a femto relay, which can be seen as another FBS or a dedicated relay, and an FBS. We assume a full-duplex relay (FDR) node which is able to transmit and receive simultaneously while suffering from residual self-interference. We focus on the performance of the femtocell according to different positions of the MU user. We derive closed-form expressions for the outage probability and spectral efficiency (throughput) taking into account the self-interference of the FDR node. Moreover, we assume that the nodes are able to apply successive interference cancellation on the MU signal. Our results show that FDR can considerably enhance the performance of the femtocell, even in the presence of strong self-interference at the FDR, allowing the femtocell to operate in a high rate regime.

3D coverage analysis of LTE urban heterogeneous networks with dense femtocell deployments

Abstract Femtocell technology recently gained attention due to its potential benefits for mobile operators (significant capacity offload and extension of the coverage at low cost) but there are still hard technical challenges to be addressed (e.g., the optimization of the interference management). Furthermore, the deployment strategies are still in question, such as the femtocell access-mode (open or closed) and the spectrum usage to adopt. Consequently, reliable simulations are necessary in the perspective of massive femtocell deployments, in particular for characterization of the impact on the coverage quality. An original solution is introduced and exploited in this article. It offers two complementary approaches for two different applications: a synthetic model for realization of small-scale or illustrative case studies and a real model for realistic and large-scale heterogeneous network performance evaluation. It relies on a suite of simulation tools including the generation of random 3D femtocell deployments in synthetic or real environments; realistic pathloss predictions; and a 3D downlink coverage performance analysis (i.e., considering all floors) of long-term evolution heterogeneous networks. A first study shows not only a large improvement of coverage quality for femtocell users, but also a very significant degradation for non-subscribers in the vicinity of closed-access femtocells. The femtocells have a strong impact locally (gain or degradation depending on the access-mode and user type) and not only at their own floor. Therefore, a 3D evaluation is relevant. Then, a second study offers realistic and large-scale analyses of the coverage evolution after corporate femtocells have massively been deployed in urban macrocells. The results show a moderate impact on the average spectral efficiencies but a strong impact locally. In this study, closed-access femtocells cause dead zones for non-subscribers in 15% of indoor areas leading to non-uniform service coverage, whereas they increase the spectral efficiency of femtocell subscribers (by 1.5 bps/Hz in 20% of indoor areas). These are critical information for a mobile operator since the experience of its customers is much affected by the femtocell deployment and by the selected access mode.

Analytical Evaluation of Fractional Frequency Reuse for Heterogeneous Cellular Networks

Interference management techniques are critical to the performance of heterogeneous cellular networks, which will have dense and overlapping coverage areas, and experience high levels of interference. Fractional frequency reuse (FFR) is an attractive interference management technique due to its low complexity and overhead, and significant coverage improvement for low-percentile (cell-edge) users. Instead of relying on system simulations based on deterministic access point locations, this paper instead proposes an analytical model for evaluating Strict FFR and Soft Frequency Reuse (SFR) deployments based on the spatial Poisson point process. Our results both capture the non-uniformity of heterogeneous deployments and produce tractable expressions which can be used for system design with Strict FFR and SFR. We observe that the use of Strict FFR bands reserved for the users of each tier with the lowest average \sinr provides the highest gains in terms of coverage and rate, while the use of SFR allows for more efficient use of shared spectrum between the tiers, while still mitigating much of the interference. Additionally, in the context of multi-tier networks with closed access in some tiers, the proposed framework shows the impact of cross-tier interference on closed access FFR, and informs the selection of key FFR parameters in open access.

The effect of Radio Resource Management in the performance of Heterogeneous Cellular Networks

Comparing market estimates for wireless personal communication and considering recent wide band multimedia services with the existing spectrum allocations for these types of systems show that spectrum resource management remains a very important topic. The coexistence of different cellular networks in the same geographical area requires joint radio resource management (JRRM) for efficient radio resource utilization and enhancement of quality of service (QoS) provisioning, maintain the planned coverage area and provide high capacity. This paper intends to provide an overview of the RRM problem and envisaged solutions in a Beyond 3G framework. Different scenarios of call admission control inheterogeneous cellular networks are analyzed and compared. Further, we focus on joint call admission control (JCAC) algorithms in heterogeneous cellular networks and present a JCAC model and assumptions for evaluating and discussing the performance of the JCAC algorithm through simulation results.

Study on X-Voronoi for Heterogeneous Wireless Sensor Networks

Coverage has recently emerged as a premier research topic. More and more research focused on coverage in wireless sensor networks using Voronoi. While most existing research efforts in the area of wireless sensor networks have focused on networks with nodes which have the same capabilities. But for Heterogeneous Wireless Sensor Networks (HWSN), which is more universal, there is a lack of study for using Voronoi solves the problem of coverage. In this paper we address on X-Voronoi for solve coverage in heterogeneous networks. Simulations confirm that the X-Voronoi is able to solve the problem of analyzing coverage performance in heterogeneous networks. To our knowledge, this is the first study on Voronoi for Heterogeneous Wireless Sensor Networks.

Octopus: monitoring, visualization, and control of sensor networks

AbstractSensor network monitoring and control are currently addressed separately through specialized tools. However, the high degree of coupling of network state to the physical environment in which the network is deployed demands that users can monitor the network and respond to network state changes continuously. This paper presents the open‐source Octopus visualization and control tool. Octopus is a protocol‐independent tool that provides live information about the network topology and sensor data in order to enable live debugging of deployed sensor networks. It enables operators to reconfigure the network behavior, such as switching between time‐driven, event‐driven, and query‐driven modes or between awake and sleep modes of one, many, or all nodes through its graphical interface. Octopus also supports changing duty cycles of nodes, data reporting period, or sensing thresholds in event‐driven networks. Reconfiguration of nodes is achieved through short request messages that support typical reconfiguration options without the overhead of epidemically sending new program images over the air. Our empirical tests showcase Octopus's capacity to debug application behavior and to characterize heterogeneous network performance under multiple settings, as a step toward establishing a rules database that relates data delivery to network‐level parameters, and toward enabling autonomous network reconfiguration. Copyright © 2009 John Wiley & Sons, Ltd.

이종 네트워크 환경에서의 LED 조명 제어 기법을 이용한 빌딩 시스템의 설계

DMX512 protocol is a typical protocol which controls LED lighting system. It has a strong feature and can be used to a lot of lighting system. But LED control system with cable has a few problem because they have a lot of control cables. It is very difficult to set up the complex lighting. Furthermore if it is set up it is not easy to keep and recover the system from the out of order. So it is required Wireless Lighting Control System. This paper describes the proposal, design, and implementation of a novel method which can provide versatile light effects with the increased capability of the mobility and the number of universes for Wireless Lighting system. And then we implement experiment environment to control indoor lighting system controled by ZigBee and WLAN converter not having complicating control line. Data frames are transferred to DMX512 device by encapsulation and decapsulation to control color LED. In the same time give the method to solve the data bottleneck problem which can be comes out because of speed difference between Heterogeneous network and measure performance of control system.

A Cost Function Model for CRRM over Heterogeneous Wireless Networks

Heterogeneous cellular networks performance is usually analysed by taking several Key Performance Indicators (KPIs) into account, their proper balance being required in order to guarantee a desired Quality of Service (QoS). An approach to simplify and integrate a set of KPIs into a single one is presented, by using the proposed Cost Function model that includes these KPIs, providing a single evaluation parameter as output, and reflecting network conditions and Common Radio Resource Management (CRRM) strategies performance. This paper proposes a Cost Function that enables the implementation of different CRRM algorithms and policies, by manipulating KPIs according to user's or operator's perspectives, allowing for a better QoS. Results show that different policies can in fact be established, with a different impact on the network, e.g., with median values ranging by a factor higher than two.

Topology control of wireless network based on different transceiver gains

The topology control optimizes wireless networks by adjusting nodes' transmission power or other performance index.Meanwhile,nodes in heterogeneous wireless network possess different features,which obstructs the optimization of wireless network with the traditional topology control algorithms developed from homogeneous networks.This paper proposed a kind of topology control model by introducing SINR into topology model,in order to solve the interference caused by nodes' different transceiver gains.By adopting hierarchical clustering algorithm,new topology control strategy could improve the performance of heterogeneous wireless networks,which is supported by simulations.

Vertical Handoff Decision Algorithms for Providing Optimized Performance in Heterogeneous Wireless Networks

There are currently a large variety of wireless access networks, including the emerging vehicular ad hoc networks (VANETs). A large variety of applications utilizing these networks will demand features such as real-time, high-availability, and even instantaneous high-bandwidth in some cases. Therefore, it is imperative for network service providers to make the best possible use of the combined resources of available heterogeneous networks (wireless area networks (WLANs), Universal Mobile Telecommunications Systems, VANETs, Worldwide Interoperability for Microwave Access (WiMAX), etc.) for connection support. When connections need to migrate between heterogeneous networks for performance and high-availability reasons, seamless vertical handoff (VHO) is a necessary first step. In the near future, vehicular and other mobile applications will be expected to have seamless VHO between heterogeneous access networks. With regard to VHO performance, there is a critical need to develop algorithms for connection management and optimal resource allocation for seamless mobility. In this paper, we develop a VHO decision algorithm that enables a wireless access network to not only balance the overall load among all attachment points (e.g., base stations and access points) but also maximize the collective battery lifetime of mobile nodes (MNs). In addition, when ad hoc mode is applied to 3/4G wireless data networks, VANETs, and IEEE 802.11 WLANs for a more seamless integration of heterogeneous wireless networks, we devise a route-selection algorithm for forwarding data packets to the most appropriate attachment point to maximize collective battery lifetime and maintain load balancing. Results based on a detailed performance evaluation study are also presented here to demonstrate the efficacy of the proposed algorithms.

Timely Effective Handover Mechanism in Heterogeneous Wireless Networks

Next-generation wireless networks should be able to coordinate and integrate different communication systems. It has been a challenging problem to support a seamless handover in these diverse wireless network environments. Link level triggers can provide information about events which can help handover decision and layer 3 entities better streamline their handover related activities. In most conventional layer 2 triggering approaches, a pre-defined threshold for a specific perspective such as the received signal strength is used. This may cause too late or too early handover executions. In this paper we propose a new predictive handover framework that uses the neighbor network information to generate timely the link triggers so that the required handover procedures can appropriately finish before the current link goes down. First we estimate a required handover time for the given neighbor network conditions, then using a predictive link triggering mechanism the handover start time is dynamically determined to minimize handover costs. The handover costs are analyzed in terms of the total required handover time and the service disruption time. The numerical analysis and simulation results show that the proposed method significantly enhances the handover performance in heterogeneous wireless networks.

Evaluations of Achievable Rate and Power Consumption in Cooperative Cellular Networks With Two Classes of Nodes

Previous work on cooperative cellular networks has mostly considered homogeneous relaying architectures where all nodes act as both sources and relays. In this paper, we examine the performance of heterogeneous cooperative cellular networks with the following two classes of nodes: source nodes (SNs) that do not act as relays and relaying agents that are dedicated to relaying functions with little concern about power consumption. In this architecture, SNs are able to reap the benefits of cooperative communications, such as improvements in the achievable data rate and reductions in the transmit power, while reducing the overall power consumption since they do not act as a relay. With an SN employing no more than two parallel relaying agents between itself and the base station, the proposed architecture achieves a 10%-80% improvement in the average achievable rate and a 15%-30% savings in the average amount of consumed power as compared to the situation where an SN can use, at most, a single relay agent.

Simultaneous baseband and RF optical modulation scheme for feeding wireless and wireline heterogeneous access networks

In this paper, a novel modulation scheme that allows broad-band optical data transmission at both baseband and millimeter-wave RF carriers at twice the local-oscillator frequency is investigated. The dispersion-induced carrier suppression may be overcome by properly setting the optical transmitter parameters. Three different configurations for the modulation scheme are modeled and simulation and experimental results are provided. The key parameters of these configurations are optimized in order to achieve the best performance in broad-band heterogeneous millimeter-wave wireless and wireline access networks.

Work-based performance measurement and analysis of virtual heterogeneous machines

Presented here is a set of methods and tools developed to provide transportable measurements of performance in heterogeneous networks of machines operating together as a single virtual heterogeneous machine (VHM). The methods are work-based rather than time-based, and yield significant analytic information. A technique for normalizing the measure of useful work performed across a heterogeneous network is proposed and the reasons for using a normalized measure are explored. It is shown that work-based performance measures are better than time-based ones because they may be (1) taken while a task is currently executing on a machine; (2) taken without interrupting production operation of the machine network; (3) used to compare disparate tasks, and (4) used to perform second-order analysis of machine network operation. This set of performance tools has been used to monitor the utilization of high-performance computing networks, provide feedback on algorithm design and determine the veracity of computing performance models.