Fair Allocation of Subcarrier and Power in an OFDMA Wireless Mesh Network

This paper presents a new fair scheduling scheme for orthogonal frequency-division multiple-access-based wireless mesh networks (WMNs), which fairly allocates subcarriers and power to mesh routers (MRs) and mesh clients to maximize the Nash bargaining solution fairness criterion. In WMNs, since not all the information necessary for scheduling is available at a central scheduler (e.g., MR), it is advantageous to involve the MR and as many mesh clients as possible in distributed scheduling based on the limited information that is available locally at each node. Instead of solving a single global control problem, we hierarchically decouple the subcarrier and power allocation problem into two subproblems, where the MR allocates groups of subcarriers to the mesh clients, and each mesh client allocates transmit power among its subcarriers to each of its outgoing links. We formulate the two subproblems by nonlinear integer programming and nonlinear mixed integer programming, respectively. A simple and efficient solution algorithm is developed for the MR's problem. Also, a closed-form solution is obtained by transforming the mesh client's problem into a time-division scheduling problem. Extensive simulation results demonstrate that the proposed scheme provides fair opportunities to the respective users (mesh clients) and a comparable overall end-to-end rate when the number of mesh clients increases     

OFDMA中继网络动态节能子载波、比特和功率联合分配策略(英文)

To reduce energy consumption while maintaining users’ Quality of Service (QoS) in Orthogonal Frequency Division Multiplex Access (OFDMA) relay-enhanced networks, an adaptive energy saving subcarrier, bit and power allocation scheme is presented. The optimal subcarrier, bit and power allocation problems based on discrete adaptive modulation and coding scheme have been previously formulated for relay-enhanced networks, and have been reformulated into and solved by integer programming in optimization theory. If the system still has a surplus of subcarriers after resource allocation, we carry out Band- width Exchange (BE) to enable more subcarriers to participate in transmission to save energy. In addition, as the relay selection scheme is closely linked with resource allocation, a heuristic energy saving relay selection scheme is proposed. Simulation results indicate that the proposed algorithm consumes less energy when transmitting the same number of bits than greedy energy saving schemes, although its spectrum efficiency is worse.     

多小区OFDMA网络中用于有效无线资源分配的ICI管理技术(英文)

Two Inter-cell Interference (ICI) management algorithms: Primary Interference Balancing (PIB) algorithm and Interfering Bits Loading Avoidance (IBLA) algorithm are proposed for canceling the ICI effects which the existing efficient radio resource allocation algorithms do not consider. The efficient radio resource allocation algorithm, i.e., Pre-assignment and Reassignment (PR) algorithm, obtains the lowest complexity and achieves good throughput performance in single cell OFDMA system. However, in multi-cel...     

Fair Algorithms for Maximal Link Activation in Multihop Radio Networks

We present a distributed algorithm for obtaining a fair time slot allocation for link activation in a multihop radio network. We introduce the concept of maximal fairness in which the termination of a fair allocation algorithm is related to maximal reuse of the channel under a given fairness metric. The fairness metric can be freely interpreted as the expected link traffic load demands, link priorities, etc. Since respective demands for time slot allocation will not necessarily be equal, we define fairness in terms of the closeness of allocation to respective link demands while preserving the collision free property. The algorithm can be used in conjunction with existing link activation algorithms to provide a fairer and fuller utilization of the channel.     

Improving Radio Resource Utilization and User Level Fairness in OFDMA Femtocell Networks

Poor indoor coverage and high cost of cellular network operators are among the main motivations for the employment of femtocell networks. Since femto access points (FAPs) and macrocells share same spectrum resources, radio resource allocation is an important challenge in OFDMA femtocell networks. Mitigating interference and improving fairness among FAPs are the main objectives in previous resource allocation methods. However, the main drawback is that user level fairness has not been adequately addressed in the previous methods, and moreover, most of them suffer from inefficient utilization of radio resources. In this paper, modeling the problem as a graph multi-coloring, a centralized algorithm is proposed to obtain both user level fairness and spectrum efficiency. This method employs a priority-based greedy coloring algorithm in order to increase the reuse factor and consequently the spectrum efficiency. Moreover, in situations where the number of available OFDM resources is not sufficient, the proposed method employs a novel fairness index to fairly share those remaining resources among users of FAPs. The performance comparison between the proposed and previous methods shows that the proposed method improves the balance between user-level fairness and resource utilization. In addition, the presented analyses show that the time complexity of the proposed method is less than that of conventional methods.     

ATM网络中ABR业务的公平速率分配

简单介绍了ＡＴＭ网络中ＡＢＲ业务的阻塞控制问题,总结了和分析了ＡＢＲ业务的２大类公平速率分配算法,并对介绍的７种算法进行了比较。     

Adaptive Resource Allocation for MC‐CDMA and OFDMA in Reconfigurable Radio Systems

This paper studies the uplink resource allocation for multiple radio access (MRA) in reconfigurable radio systems, where multiple‐input and multiple‐output (MIMO) multicarrier‐code division multiple access (MC‐CDMA) and MIMO orthogonal frequency‐division multiple access (OFDMA) networks coexist. By assuming multi‐radio user equipment with network‐guided operation, the optimal resource allocation for MRA is analyzed as a cross‐layer optimization framework with and without fairness consideration to maximize the uplink sum‐rate capacity. Numerical results reveal that parallel MRA, which uses MC‐CDMA and OFDMA networks concurrently, outperforms the performance of each MC‐CDMA and OFDMA network by exploiting the multiuser selection diversity.     

Joint Downlink Scheduling and Radio Resource Allocation for User-Individual QoS in Adaptive OFDMA Wireless Communication Systems

1Introduction Futurewirelessandmobilecommunicationsystems areexpectedtoofferhigherdatarates,tosupporta largenumberofsubscribersandtoensurethefulfillment ofQualityofService(QoS)requirements,giventhe limitedavailabilityoffrequencyspectrumandtimevary ingchan…     

An Efficient and Fair Strategy for Radio Resources Allocation in Multi-radio Wireless Mesh Networks

A Load and Interference aware Resource Allocation strategy (LIRA) is proposed for multi-radio Wireless Mesh Networks (WMNs), combining multiple mechanisms that efficiently optimise radio resources (rate, power and channel) to guarantee max–min fair capacity to every aggregating Mesh Access Point (MAP). LIRA is composed of a rate adaptation and power control mechanism, sensitive to the fat-tree traffic specificities of WMNs, using the highest bit rates at MAP gateways and using, for the ramified links, the minimum ones that satisfy their capacity needs. This enables to efficiently reduce the transmitted power and interference, advantageous for channel reutilisation. LIRA also integrates a load and interference aware channel assignment mechanism, allowing the simultaneous operation of all links without interference. When this is not achievable, two auxiliary mechanisms of channel sharing and interference-free channel reuse can be sub-sequentially used, reducing the capacity of certain MAPs to guarantee fairness to all nodes. LIRA’s gateway flow-control mechanism guarantees that all MAPs respect the allocated capacity, guaranteeing that every MAP is able to operate at its max–min fair capacity. The performance of LIRA is evaluated through simulation, considering IEEE 802.11a. For a classical hexagonal deployment of 19 MAPs with an Internet gateway, it is shown how with only 5 channels LIRA guarantees to every MAP a max–min fair capacity of 3.2 Mbit/s, without packet loss, and delay below 6 ms. It guarantees a max–min fair throughput to every MAP, having a capacity usage efficiency of 66.7 %, an energy efficiency of 26.5 Mbit/J and spectrum efficiency of 0.58 bit/s/Hz. For a more challenging scenario with 27 MAPs and 4 gateways, it is shown how LIRA uses its mechanisms in heterogeneous conditions to also guarantee max–min fair throughput to every MAP, between 5 and 11 Mbit/s, without packet loss, and a delay below 12 ms. Any system improvement will enable to reach higher WMN performance levels using the proposed strategy.     

认知网络下TCP协议性能分析

首先在无线环境下的基础上搭建认知平台,当主用户想要占次用户信道时,通过基站的频谱监测,频谱分配,分配次用户到其他空闲信道继续通信.其次,在此平台下分析TCP Reno,TCP Newreno,TCP Sackl和TCP vegas协议的性能,包括拥塞窗口、吞吐量.最后定量分析主用户活跃程度、切换后信道带宽和信道误比特率...     

认知无线电环境下TCP性能分析

首先讨论分析了认知无线电环境下影响TCP性能的关键因素,并通过NS2仿真软件搭建认知网络环境,仿真分析了不同TCP版本协议在认知网络环境下的性能状况,包括reno,newreno,westwood,vegas和sack。仿真结果表明,在认知网络环境下,westwood性能最好而vegas最差。     

MPEG-4 Video Transmission over Wireless Networks: A Link Level Performance Study

With the scalability and flexibility of the MPEG-4 and the emergence of the broadband wireless network, wireless multimedia services are foreseen to become deployed in the near future. Transporting MPEG-4 video over the broadband wireless network is expected to be an important component of many emerging multimedia applications. One of the critical issues for multimedia applications is to ensure that the quality-of-service (QoS) requirement to be maintained at an acceptable level. This is further challenged in that such a service guarantee must be achieved under unreliable and time-varying wireless channels. In this paper we study the link level performance of MPEG-4 video transmission over the uplink of an unreliable wireless channel. We introduce the discrete time batch Markovian arrival process (DBMAP) with two types of arrivals to model the MPEG-4 video source, which takes into account the inherent nature of the adaptiveness of the video traffic. We prove that in a hidden Markov modeled (HMM) wireless channel with probabilistic transmission, the service time for an arbitrary radio link control (RLC) burst follows phase type (PH-type) distribution. We show that the link level performance of a wireless video transmission system can be modeled by a DBMAP/PH/1 priority queue, and present computation algorithm and numerical results for the queueing model. Extensive simulations are carried out on the queueing behavior of the video transmission buffer, as well as on the packet level error behavior of the video data. The results demonstrate that video quality can be substantially improved by preserving the high priority video data during the transmission.     

Joint Power and Rate Control Combined with Adaptive Modulation in Cognitive Radio Networks

Efficient resource allocation is a major challenge in cognitive radio networks, especially when Cognitive Users (CUs) share the same frequency band with the Primary User. In this paper, we consider minimizing the total power consumption by combining power control, rate control and adaptive modulation. We analyze the existence, uniqueness and Pareto optimality of Nash Equilibrium (NE) in the power control game, and propose an iterative algorithm to find the NE followed by the adjustment of both the transmission rate and modulation scheme based on the convergent power. If compared with previous works, the key feature of the proposed strategy is that each CU can prolong its battery life in energy-constrained networks to support heterogenous services with different transmission rates and modulation schemes requirements. Simulation results are provided to confirm the effectiveness of the proposed method in power saving, improvement of both the transmission rate and the spectral efficiency and the simplicity of implementation.     

认知网络中的能量回收技术：性能分析及优化设计

通信网络中有限的能源和频带资源限制了网络容量的进一步提升.对能量回收技术在认知网络中的应用进行研究,量化评估用户可回收的能量以及可达吞吐率,并进行优化设计很有必要.在所分析的系统中,当授权用户进行通信时,非授权用户可回收无线信号中所带有的能量,并利用回收的能量进行频谱检测;当检测到授权用户空闲时,非授权用户将接入频谱,利用回收到的能量进行数据传输.采用马尔科夫链模型对通信场景进行描述分析,发现授权用户的活跃程度对非授权用户可回收的能量、获得的传输机会带来影响,进而决定了非授权用户的可达吞吐量.在此基础上,提出一种通过控制授权用户业务量,以最大化网络能量效用和频谱效用的优化方案,并通过仿真证实了理论分析的正确性.     

认知无线网络中的频谱切换性能分析

在认知无线网络中,次用户的频谱切换性能不仅和主用户的通信行为关系密切,而且也和次用户本身的频谱感知精度以及频谱切换策略密切相关。该文采用连续时间马尔科夫模型对次用户在理想感知和非理想感知情况下的频谱切换进行建模,进一步分析与比较不同频谱感知精度对频谱切换性能的影响。为了有效降低次用户在频谱切换过程中的强制中断概率,提出基于信道预留机制的频谱切换策略。数值结果表明,次用户对主用户信号的感知精度明显会影响次用户的频谱切换性能,而有效的频谱切换策略则可以以较小的代价获得更好的频谱切换性能。     

CDMA2000无线链路上TCP性能分析及优化

通过基于RLP的TCP仿真平台,分析了有无RLP、RLP重传次数、TCP窗口大小、TCPSACK等方面对提高TCP性能的作用;还对CDMA2000中影响TCP性能的其他特性进行了进一步分析;并提出了有针对性的优化措施。     

三层卫星光网络链路性能分析

分析了三层卫星光网络的链路类型、时延和网络稳定性等参数，结果表明与单层卫星光网络比较，三层卫星光网络吞吐量大、鲁棒性强。同时由于其结构复杂导致网络中链路负载加重、路由表计算量和阻塞概率增大。这为今后卫星光通信组网技术研究和空间光通信协议的拟定提供了参考。     

Performance Analysis of Dynamic Spectrum Allocation in Heterogeneous Wireless Networks

Increasing convergence among heterogeneous radio networks is expected to be a key feature of future ubiquitous services. The convergence of radio networks in combination with dynamic spectrum allocation (DSA) could be a beneficial means to solve the growing demand for radio spectrum. DSA might enhance the spectrum utilization of involved radio networks to comply with user requirements for high‐quality multimedia services. This paper proposes a simple spectrum allocation algorithm and presents an analytical model of dynamic spectrum resource allocation between two networks using a 4‐D Markov chain. We argue that there may exist a break‐even point for choosing whether or not to adopt DSA in a system. We point out certain circumstances where DSA is not a viable alternative. We also discuss the performance of DSA against the degree of resource sharing using the proposed analytical model and simulations. The presented analytical model is not restricted to DSA, and can be applied to a general resource sharing study.     

Resource Allocation in Cognitive Radio Networks Using Stackelberg Game: A Survey

Wireless Personal Communications - With the promise of improving the spectrum utilization of wireless devices, cognitive radio technology has gained a significant amount of interest from the...