WiMax网络中自相似呼叫接纳控制算法研究

针对WiMAX网络业务流的自相似特性,提出用M/Pareto模型来对网络业务流进行建模,通过M/Pareto模型和FBM业务流模型之间统计性质得到2个模型间的参数映射关系,推导出基于M/Pareto模型参数的有效带宽计算公式,据此设计出一个自相似接纳控制算法(SS-CAC)。该算法避免了通过测量的方法来获取FBM业务流模型中参数值,又适应了WiMAX网络流自相似这一特性,使得计算的有效带宽更加精确和方便,提高了系统资源利用率。仿真结果表明,该算法极大地提高网络的带宽利用率,降低了系统的呼叫阻塞率。     

Supporting multi-user real-time VBR video service using dynamic bandwidth management based on prediction

Real-time variable bit rate (VBR) video is expected to take a significant portion of multimedia applications. However, plentiful challenges to VBR video service provision have been raised for its characteristic of high traffic abruptness. To support multi-user real-time VBR video transmission with high bandwidth utilization and satisfied quality of service (QoS), this article proposes a practical dynamic bandwidth management scheme. This scheme forecasts future media rate of VBR video by employing time-domain adaptive linear predictor and using media delivery index (MDI) as both QoS measurement and complementary management reference. In addition, to support multi-user application, an adjustment priorities classified strategy is also put forward. Finally, a test-bed based on this management scheme is established. The experimental results demonstrate that the scheme proposed in this article is efficient with bandwidth utilization increased by 20%-60% compared to a fixed service rate and QoS guaranteed.     

A probabilistic approach for fair-efficient call admission control in wireless multiservice networks

The efficiency of call admission control (CAC) schemes in multiclass wireless networks should be evaluated not only with regard to the call blocking probability (CBP) achieved for every service class (SC) supported but also with regard to quality of service (QoS) and network efficiency criteria. In this article, four CAC schemes offering priority to SCs of advanced QoS requirements, based on guard channel policy, are studied and evaluated taking into account fairness and throughput criteria in addition to CBP. For the performance evaluation of the proposed CAC schemes and to examine fairness issues, two fairness indices are introduced along with a throughput metric. The analytical results, validated through extensive simulations, indicate that by appropriate selection of the CAC parameters satisfactory fairness and throughput are achieved while achieving low CBP.     

Real‐time VP bandwidth control for long‐range‐dependent traffic

The asymptotics of cell loss ratio (CLR) in the regime of large buffers are exponential and can be characterized by two parameters, the asymptotic constant and asymptotic decay rate. This result is very general, provided that the arrival process does not possess long‐range dependence. As for the long‐range dependent case (or equivalently, when the increment of the traffic process is self‐similar), the CLR decreases with the buffer size sub‐exponentially, and the two parameters are no longer adequate to capture this phenomenon. Recent results from the literature show that for self‐similar traffic models the tail of the stationary queue length distribution is Weibullian. Using these results, this paper proposes an algorithm for estimating the CLR in real time based on buffer measurements, which works for both the long‐range‐ and the short‐range‐dependent case. For this purpose, the notion of state‐space representation of a single‐server queue is introduced, and Bayesian regression analysis is applied to estimate the state variable of that system. Our approach does not require any models describing the statistics of the traffic other than the asymptotic behaviour of the CLR. We describe how our method can be applied to VP bandwidth control by using results from simulation experiments. Copyright © 1999 John Wiley & Sons, Ltd.     

Bandwidth allocation and admission control scheme based on Nash bargaining solution for WiMAX systems

Development of fair and efficient bandwidth allocation and admission control schemes is one of the key issues in the design of IEEE 802.16 broadband wireless access systems in time division multiple access (TDMA) mode. In this article, the problem of bandwidth allocation and admission control is formulated as a Nash bargaining model. The nash bargaining solution (NBS) derived from the cooperative game is adopted to maximize the spectrum utilization. Analysis and simulation results show that there is a unique Pareto optimal bandwidth allocation solution by using NBS among various flows. Furthermore, maximum utility of the system can also be maintained by using the admission control policy with different number of connections and variable channel qualities. The total throughput of the proposed scheme is close to the maximal one, while significantly improving fairness compared to the existing solutions.     

Power allocation and call admission control in multi‐class traffic DS‐CDMA systems with imperfect power control

We deal with power allocation (PA) and call admission control (CAC) under imperfect power control (IPC) in the reverse link of direct sequence‐code division multiple access systems for supporting multi‐class traffic. First, we briefly review the optimum PA scheme under perfect power control (PPC) and the CAC scheme subject to an outage constraint on the total composite received power. Then, we analyze the outage degradation due to the power control error when the optimum reference power levels under PPC are used. In order to mitigate the outage degradation, we would modify the reference power levels by incorporating a call dropping strategy and an outage‐lowering strategy into the optimum PA scheme under PPC. Also, we derive a constraint inequality to determine the reverse link capacity under IPC. Finally, through numerical analyses, we compute the modified reference power levels under IPC and evaluate the reverse link capacity under IPC. Copyright © 2006 John Wiley & Sons, Ltd.     

An optimal bandwidth allocation and data droppage scheme for differentiated services in a wireless network

This paper presents an optimal proportional bandwidth allocation and data droppage scheme to provide differentiated services (DiffServ) for downlink pre‐orchestrated multimedia data in a single‐hop wireless network. The proposed resource allocation scheme finds the optimal bandwidth allocation and data drop rates under minimum quality‐of‐service (QoS) constraints. It combines the desirable attributes of relative DiffServ and absolute DiffServ approaches. In contrast to relative DiffServ approach, the proposed scheme guarantees the minimum amount of bandwidth provided to each user without dropping any data at the base‐station, when the network has sufficient resources. If the network does not have sufficient resources to provide minimum bandwidth guarantees to all users without dropping data, the proportional data dropper finds the optimal data drop rates within acceptable levels of QoS and thus avoids the inflexibility of absolute DiffServ approach. The optimal bandwidth allocation and data droppage problems are formulated as constrained nonlinear optimization problems and solved using efficient techniques. Simulations are performed to show that the proposed scheme exhibits the desirable features of absolute and relative DiffServ. Copyright © 2009 John Wiley & Sons, Ltd.     

A call admission control for service differentiation and fairness management in WDM grooming networks

We investigate a call admission control (CAC) mechanism for providing fairness control and service differentiation in a WDM network with grooming capabilities. A WDM grooming network can handle different classes of traffic streams which differ in their bandwidth requirements. We assume that for each class, call interarrival and holding times are exponentially distributed. Using a Markov Decision Process approach, an optimal CAC policy is derived for providing fairness in the network. The Policy Iteration algorithm is used to numerically compute the optimal policy. Furthermore, we propose a heuristic decomposition algorithm with lower computational complexity and good performance. Simulation results compare the performance of our proposed policy with those of Complete Sharing and Complete Partitioning policies. Comparisons show that our proposed policy provides the best performance in most cases. Although this approach is motivated by WDM networks, it may be deployed to determine the optimal resource allocation in many problems in wireless and wired telecommunications systems.     

Comparison of VBR and CBR service classes for MPEG‐2 video multiplexing—Is statistical multiplexing really useful for bursty video transmission?

It has been believed that a statistical multiplexing technique can bring an effective bandwidth usage. When it is applied to MPEG‐2 video, it has been pointed out that two to several times multiplexing gain can be attained due to the highly bursty nature of video traffic. However, most of the past researches do not take into account the implementation aspects of this technique. In this paper, we thoroughly investigate the actual multiplexing gain by comparing ATM CBR and VBR service classes (deterministic and statistical service classes), and point out that the statistical multiplexing gain is far from what one might expect. Copyright © 2001 John Wiley & Sons, Ltd.     

Cross‐layer bandwidth and power allocation for a two‐hop link in wireless mesh network

In this paper, a cross‐layer analytical framework is proposed to analyze the throughput and packet delay of a two‐hop wireless link in wireless mesh network (WMN). It considers the adaptive modulation and coding (AMC) process in physical layer and the traffic queuing process in upper layers, taking into account the traffic distribution changes at the output node of each link due to the AMC process therein. Firstly, we model the wireless fading channel and the corresponding AMC process as a finite state Markov chain (FSMC) serving system. Then, a method is proposed to calculate the steady‐state output traffic of each node. Based on this, we derive a modified queuing FSMC model for the relay to gateway link, which consists of a relayed non‐Poisson traffic and an originated Poisson traffic, thus to evaluate the throughput at the mesh gateway. This analytical framework is verified by numerical simulations, and is easy to extend to multi‐hop links. Furthermore, based on the above proposed cross‐layer framework, we consider the problem of optimal power and bandwidth allocation for QoS‐guaranteed services in a two‐hop wireless link, where the total power and bandwidth resources are both sum‐constrained. Secondly, the practical optimal power allocation algorithm and optimal bandwidth allocation algorithm are presented separately. Then, the problem of joint power and bandwidth allocation is analyzed and an iterative algorithm is proposed to solve the problem in a simple way. Finally, numerical simulations are given to evaluate their performances. Copyright © 2008 John Wiley & Sons, Ltd.     

Multi‐stage two‐leg bandwidth reservation and admission control for advance reservations with uncertain service duration

In traditional advance reservation (AR) service, resources were reserved for fixed scheduled periods at the time requests were admitted. When overtimes occurred, because of the reservation timeout, connections would be forced to terminate. For Internet AR applications like sports event casting and conference meetings such service disruption would be unfortunate and undesired for the viewers and participants. Further, taking into account that overtimes are often known almost at the last minute of the pre‐scheduled period, even if a connection extension request is submitted the probability that it is successful is unpredictable depending on the network load. In this paper, we study the problem of admission control and resource management for the AR service with uncertain service duration. An innovative multi‐stage two‐leg admission control and bandwidth management scheme is proposed. New performance measures—service quality indexes and reservation cost function are also defined for AR service. Through simulations, we show that the proposed scheme successfully provides service users a more predictive, affirmative service guarantee than conventional reservation schemes. Copyright © 2006 John Wiley & Sons, Ltd.     

Radio resource management games in wireless networks: an approach to bandwidth allocation and admission control for polling service in IEEE 802.16 [Radio Resource Management and Protocol Engineering for IEEE 802.16]

Game theory is a mathematical tool developed to understand competitive situations in which rational decision makers interact to achieve their objectives. Game theory techniques have recently been applied to various engineering design problems in which the action of one component impacts (and perhaps conflicts with) that of any other component. In particular, game theory techniques have been successfully used for protocol design and optimization (e.g., radio resource management, power control) in wireless networks. In this article we present an overview of different game theory formulations. Then a survey on the game-theory-based resource management and admission control schemes in different wireless networks is presented, and several open research issues are outlined. To this end, we propose an adaptive bandwidth allocation and admission control scheme for polling service in an IEEE 802.16-based wireless metropolitan area network. A noncooperative game is formulated, and the solution of this game is determined by the Nash equilibrium for the amount of bandwidth offered to a new connection. The admission control policy ensures QoS for all connections in the system     

Measurement‐based admission control scheme with priority and service classes for application in wireless IP networks

Wireless IP networks will provide voice and data services using IP protocols over the wireless channel. But current IP is unsuitable to provide delay or loss bounds and insufficient to support diverse quality of service, both required by real‐time applications. In order to support real‐time applications in wireless IP networks, in this paper a measurement‐based admission control (MBAC) with priority criteria and service classes is considered. First we have shown the suitability of MBAC in wireless IP networks by comparing its performance with a parameter‐based scheme. Next, we have investigated the performance of strictly policy‐based MBAC and policy plus traffic characteristic‐based MBAC schemes in terms of (1) increasing the user mobility, (2) changing traffic parameters and (3) the presence of greedy users. The efficiency and fairness of each scheme are measured in terms of lower class new and handoff traffic performance. Copyright © 2003 John Wiley & Sons, Ltd.     

Asymptotic design of quantization and bit allocation for distributed estimation in wireless sensor networks

This paper investigates the schemes of asymptotically optimal quantization and bit allocation for distributed estimation in wireless sensor networks in which a total bit rate constraint is imposed. Because there is no communication among all sensors, quantizers for observations need to be designed separately. The Lloyd‐Max quantizer is shown to be asymptotically optimal for each sensor. Moreover, it is shown that the level number of asymptotically optimal quantization for sensors is proportional to the signal‐to‐noise ratio, which is determined by the variances of observation and noise. Because the original quantized minimum mean‐square error estimator often corresponds to a high computational cost when a large number of sensors are active, in our work, an asymptotically equivalent algorithm of iterative quantized estimator (IQE), which enjoys a low computational cost, is proposed. In addition, an IQE algorithm can be applied to wireless sensor networks with delay or packet loss. Simulation results of this work indicate that the effectiveness of our IQE algorithm is obvious; that is, a significant improvement of estimation performance is achieved by using the optimal bit allocation when comparing with the uniform bit allocation. Copyright © 2016 John Wiley & Sons, Ltd.     

SINR and throughput improvement for VANET using fuzzy power control

This paper proposes transmission power control for vehicular ad hoc network (VANET) using fuzzy system. Despite the potential advantages of VANET especially for safety and intelligent transportation system, some challenges are discovered during the implementation of VANET. Main challenges emerge because of the dynamic environment and high mobility of vehicle. Furthermore, the interference due to the shared‐spectrum usage can significantly decrease the quality of signal. Fuzzy system is implemented to control the transmission power based on the signal to interference and noise ratio (SINR) difference with the targeted value of the receiver vehicle and the interference inflicted by the transmitter vehicle. The algorithm of fuzzy power control for VANET is proposed, and the performance is evaluated through the simulations. The results of simulations show that the proposed algorithm can increase SINR of vehicles especially the vehicles with SINR value below the target. Thus, the average of SINR and the throughput of the system can be increased as well.     

Low peak‐to‐average power ratio and efficient multicarrier spread spectrum transceivers using hybrid and quadrature cyclic shift orthogonal keying

This paper proposes two bandwidth and power efficient multicode multicarrier spread spectrum (MCSS) system modes based on a new cyclic shift orthogonal keying (CSOK) scheme that leads to low peak‐to‐average power ratio (PAPR) signals. Both system modes can improve the bandwidth efficiency by loading more data bits per symbol block. The first system mode is the hybrid CSOK (HCSOK) mode, which combines phase shift keying (PSK) or quadrature amplitude modulation (QAM) modulation symbol with the CSOK symbol, for example, the important hybrid quadrature PSK (QPSK)–CSOK case. The second is the quadrature CSOK (QCSOK) mode that transmits two parallel binary phase shift keying (BPSK)–CSOK branches at the same time. For both modes, maximum likelihood receivers are derived and simplified, leading to efficient fast Fourier transform‐based structures for maximum ratio combining and cyclic‐code correlation. Theoretical bit error rate (BER) analysis is conducted for the hybrid QPSK–CSOK case. Simulation results demonstrate that both the two system modes considerably outperforms the traditional Walsh‐coded MCSS system in terms of bandwidth efficiency, PAPR, BER, and antijamming capability. Furthermore, in indoor channel, QCSOK performs slightly worse than QPSK–CSOK, but it has almost twice the data rate when the code length is large. Copyright © 2011 John Wiley & Sons, Ltd.