A demand assignment system for mobile users in a community ofinterest

The paper presents a high performance wireless access and switching system for interconnecting mobile users in a community of interest. Radio channel and time slot assignments are made on user demand, while the switch operations are controlled by a scheduling algorithm designed to maximize utilization of system resources and optimize performance. User requests and assignments are carried over a low-capacity control channel, while user information is transmitted over the traffic channels. The proposed system resolves both the multiple access and the switching problems and allows a direct connection between the mobile end users. The system also provides integration of voice and data traffic in both the access link and the switching equipment. The “movable boundary” approach is used to achieve dynamic sharing of the channel capacity between the voice calls and the data packets. Performance analysis based on a discrete time Markov model, carried out for the case of optimum scheduling yields call blocking probabilities and data packet delays. Performance results indicate that data packets may be routed via the exchange node with limited delays, even with heavy load of voice calls. Also the authors have proposed scheduling algorithms that may be used in implementing this system     

Adaptive resource allocation for prioritized call admission over anATM-based wireless PCN

In future personal communications networks (PCNs) supporting network-wide handoffs, new and handoff requests will compete for connection resources in both the mobile and backbone networks. Forced call terminations due to handoff call blocking are generally more objectionable than new call blocking. The previously proposed guard channel scheme for radio channel allocation in cellular networks reduces handoff call blocking probability substantially at the expense of slight increases in new call blocking probability by giving resource access priority to handoff calls over new calls in call admission control. While the effectiveness of a fixed number of guard channels has been demonstrated under stationary traffic conditions, with nonstationary call arrival rates in a practical system, the achieved handoff call blocking probability may deviate significantly from the desired objective. We propose a novel dynamic guard channel scheme which adapts the number of guard channels in each cell according to the current estimate of the handoff call arrival rate derived from the current number of ongoing calls in neighboring cells and the mobility pattern, so as to keep the handoff call blocking probability close to the targeted objective while constraining the new call blocking probability to be below a given level. The proposed scheme is applicable to channel allocation over cellular mobile networks, and is extended to bandwidth allocation over the backbone network to enable a unified approach to prioritized call admission control over the ATM-based PCN     

Resource allocation for cellular radio systems

High terminal traffic densities are expected in urban multiuser radio systems. An efficient allocation of resources is the key to high system capacity. In this paper, a distributed dynamic resource allocation (DDRA) scheme based on local signal and interference measurements is proposed for multiuser radio networks. It offers “soft capacity” for time division multiple access (TDMA) and frequency division multiple access (FDMA) systems, bounded above by N per base station, where N is the total number of channels in the system. The decisions are made local to a terminal and its base and are essentially independent of the rest of the system. A distributed dynamic channel assignment scheme is used to assign channels to new calls. This scheme assigns a channel that offers the maximum carrier to interference ratio (CIR) to a new call. A distributed constrained power control (DCPC) scheme based on CIR measurements is used for power control. The channel assignment scheme and the power control scheme are coupled to obtain an interactive resource allocation scheme. We compare the capacity of a system which uses the distributed dynamic resource allocation scheme described above with the capacity of a system which uses the channel assignment scheme alone. The system capacity is measured by simulation as the number of terminals that can be served by the system with a CIR above an acceptable minimum. In a 1D cellular system, coupling the channel assignment scheme with power control is discussed. Simulations were also used to show the effect of varying the maximum transmitter power on system capacity     

Demand assignment multiple access and dynamic channel allocationstrategies for integrating radio dispatch and telephone services overmobile satellite systems

The authors discuss the performance analyses of a novel demand assignment multiple access (DAMA) scheme addressing the special characteristics of the mobile radio service (MRS), and a new method for dynamically allocating a common pool of channels to both MRS and mobile telephone service (MTS) to improve channel utilization. The new DAMA scheme makes use of call queuing, batch processing, and pipelined signaling to minimize call setup overhead for MRS traffic. MRS call setup delays were analyzed by simulation modeling of a mobile satellite system (MSS) with many mobile voice-dispatch networks operating over a multiple spot beam satellite to investigate the effects of traffic volume, batch size, and batch service disciplines. A reserved channel margin algorithm for dynamic channel allocation was shown to be effective in harmonizing the different call setup performance requirements for MTS and MRS. Numerical results show that dynamic channel allocation applied to a common pool of 40 channels enables a 20-25% increase in the number of mobile terminals compared with a fixed allocation of 20 channels to each of the two services     

准静止状态下的高空平台实时业务信道分配

受平台准静止状态的影响,高空平台（ HAPS)通信网络内存在大量的切换呼叫,且业务量动态变化。 HAPS网络可传输多种业务,其中实时业务在切换过程中具有较高的时延要求。通过为切换呼叫预留信道可降低平台不稳定对服务质量（ QoS)造成的影响。在基于服务优先级的多业务信道分配算法基础上,重点对实时业务的信道分配算法进行改进,提出了一种基于概率的预留信道借用策略。该算法可根据网络内业务量的实时统计数据控制新呼叫业务的准入。仿真结果表明：与固定预留信道算法和门限预留信道算法相比,该算法能够适应网络内业务量的动态变化,在保证切换呼叫掉线率满足期望值的条件下提升系统的整体性能,降低平台不稳定造成的性能损失。     

Integrated predictive power control and dynamic channel assignment in mobile radio systems

It is known that dynamic allocation of channels and power in a frequency/time-division multiple access system can improve performance and achieve higher capacity. Various algorithms have been separately proposed for dynamic channel assignment (DCA) and power control. Moreover, integrated dynamic channel and power allocation (DCPA) algorithms have already been proposed based on simple power control algorithms. In this paper, we propose a DCPA scheme based on a novel predictive power control algorithm. The minimum interference DCA algorithm is employed, while simple Kalman filters are designed to provide the predicted measurements of both the channel gains and the interference levels, which are then used to update the power levels. Local and global stability of the network are analyzed and extensive computer simulations are carried out to show the improvement in performance, under the dynamics of user arrivals and departures and user mobility. It is shown that call droppings and call blockings are decreased while, on average, fewer channel reassignments per call are required.     

NACR: A New Adaptive Channel Reservation in Cellular Communication Systems

Future Personal Communication Networks (PCN) will employ microcells and picocells to support a higher capacity, thus increasing the frequency of handoff calls. Forced call terminations due to handoff call blocking are generally more objectionable than new call blocking. The proposed guard channel schemes for radio channel allocation in cellular networks reduce handoff call blocking probability at the expense of increases in new call blocking probability by giving resource access priority to handoff calls over new calls in call admission control. Under uniform traffic assumptions, it has been shown that a fixed number of guard channels leads to good performance results. In a more realistic system, non-uniform traffic conditions should be considered. In this case, the achieved call blocking probability may deviate significantly from the desired objective. In this paper, we propose a new adaptive guard channel scheme: New Adaptive Channel Reservation (NACR). In NACR, for a given period of time, a given number of channels are guarded in each cell for handoff traffic. An approximate analytical model of NACR is presented. Tabu search method has been implemented in order to optimize the grade of service. Discrete event simulations of NACR were run. The effectiveness of the proposed method is emphasized on a complex configuration.     

A Hopfield neural-network-based dynamic channel allocation withhandoff channel reservation control

As channel allocation schemes become more complex and computationally demanding in cellular radio networks, alternative computational models that provide the means for faster processing time are becoming the topic of research interest. These computational models include knowledge-based algorithms, neural networks, and stochastic search techniques. This paper is concerned with the application of a Hopfield (1982) neural network (HNN) to dynamic channel allocation (DCA) and extends previous work that reports the performance of HNN in terms of new call blocking probability. We further model and examine the effect on performance of traffic mobility and the consequent intercell call handoff, which, under increasing load, can force call terminations with an adverse impact on the quality of service (QoS). To maintain the overall QoS, it is important that forced call terminations be kept to a minimum. For an HNN-based DCA, we have therefore modified the underlying model by formulating a new energy function to account for the overall channel allocation optimization, not only for new calls but also for handoff channel allocation resulting from traffic mobility. That is, both new call blocking and handoff call blocking probabilities are applied as a joint performance estimator. We refer to the enhanced model as HNN-DCA++. We have also considered a variation of the original technique based on a simple handoff priority scheme, here referred to as HNN-DCA+. The two neural DCA schemes together with the original model are evaluated under traffic mobility and their performance compared in terms of new-call blocking and handoff-call dropping probabilities. Results show that the HNN-DCA++ model performs favorably due to its embedded control for assisting handoff channel allocation     

Dynamic channel allocation in interference-limited cellular systemswith uneven traffic distribution

Most recently proposed wireless dynamic channel allocation methods have used carrier-to-interference (C/I) information to increase the system performance. Power control is viewed as essential for interference-limited systems. However, the performance of such systems under an imbalance of load among cells, as may occur often in microcells, is largely unknown. Here, we study a typical interference-limited dynamic channel allocation policy. Calls are accepted if a channel can be assigned that will provide a minimum C/I, and power control and intracell handoffs are used to maintain this level. We focus on the relationship between system performance and the amount of imbalance in load among neighboring cells. Previous studies for systems that do not use C/I information have found that dynamic channel allocation (DCA) outperforms fixed channel allocation (FCA) in all but heavily loaded systems with little load imbalance. We present two principal new results. First, we find that with use of C/I information, the difference in performance between FCA and DCA (in terms of throughput or blocking probability) is increasing with load imbalance. DCA was found to be more effective in congestion control at the cost of a slightly lower call quality. Second, we find that use of power control to maintain a minimum C/I results in two equilibrium average power levels for both DCA and FCA, with DCA using a higher average power than FCA, and that while DCA's power is increasing with load imbalance, FCA's average power is decreasing with load imbalance     

认知型飞蜂窝网络中的子信道分配与功率控制

为了解决宏蜂窝与飞蜂窝构成的两层异构网络上行干扰与资源分配问题,提出了一种在认知型飞蜂窝的双层异构网中结合子信道分配和功率控制进行资源分配的框架。通过对异构网中跨层干扰问题进行分析与建模,将求解最优子信道分配矩阵和用户发射功率矩阵作为干扰管理问题的解决方法。模型中认知型飞蜂窝网络子信道和飞蜂窝网络用户构成非合作博弈,双方利用效用函数最优值进行匹配,构成初始信道分配矩阵;再由接入控制器根据接入条件从初始信道分配矩阵中筛选用户,并优化接入用户的发射功率矩阵,得到最优子信道分配矩阵和功率矩阵。仿真结果表明,优化框架提高了双层异构网络中飞蜂窝网络用户的吞吐量和接入率,降低了异构网中跨层干扰。     

卫星通信系统多优先级信道预留分配策略

随着通信系统的不断发展,对融合地面系统的天地一体化网络的研究越来越多,而卫星通信系统中,由于卫星高速移动等特性,不可避免需要对呼叫的接入切换进行研究。针对天地一体化信息网络需要支持多场景多业务情况下的通信需求,考虑不同呼叫优先级不同,对多优先级的多种呼叫业务进行考虑。根据信道预留的思想,对不同优先级接入与切换呼叫设定不同的可用信道数,优先级越高的呼叫,为其留更多的可用信道以确保其接入信道成功。同时,由于动态信道预留较固定信道预留能够更好地利用信道资源,最终考虑多优先级下的动态信道预留策略。对多优先级动态信道预留与多优先级固定信道预留策略进行仿真验证,发现动态预留方案得到的系统服务质量更好。对于单一策略,发现优先级越高的用户接入与切换呼叫接入信道失败率更低。     

Q-Win – A New Admission and Handoff Management Scheme for Multimedia LEO Satellite Networks

Low Earth Orbit (LEO) satellite networks are deployed as an enhancement to terrestrial wireless networks in order to provide broadband services to users regardless of their location. In addition to global coverage, these satellite systems support communications with hand-held devices and offer low cost-per-minute access cost, making them promising platform for Personal Communication Services (PCS). LEO satellites are expected to support multimedia traffic and to provide their users with the negotiated Quality of Service (QoS). However, the limited bandwidth of the satellite channel, satellite rotation around the Earth and mobility of end-users makes QoS provisioning and mobility management a challenging task. One important mobility problem is the intra-satellite handoff management. The main contribution of this work is to propose Q-Win, a novel call admission and handoff management scheme for LEO satellite networks. A key ingredient in our scheme is a companion predictive bandwidth allocation strategy that exploits the topology of the network and contributes to maintaining high bandwidth utilization. Our bandwidth allocation scheme is specifically tailored to meet the QoS needs of multimedia connections. The performance of Q-Win is compared to that of two recent schemes proposed in the literature. Simulation results show that our scheme offers low call dropping probability, providing for reliable handoff of on-going calls, good call blocking probability for new call requests, while maintaining bandwidth utilization high.     

Bandwidth Allocation Strategies in Wide-Band Integrated Networks

A common digital transmission facility in a wide-band integrated service digital network (ISDN) provides shared access to a community of heterogeneous users. Traffic demands from these users vary in their arrival rate, their service time, and their bit rate. In order for this type of communication system to handle its traffic demands with high efficiency and flexibility, a close control of access to the shared bandwidth is required. We model the system by a general multiserver queueing system where customers demand service from a random number of servers. If no waiting is allowed, this queueing model is readily analyzed, and various server allocation strategies can be studied. If the various access requests are queued for service, then the system calls for efficient strategies for allocating servers to waiting customers. In this case, exact analysis of the underlying queueing model becomes quite difficult. For this case, we present some analytic and simulation results of the performance of the system under several server allocation policies.     

Teletraffic performance evaluation of microcellular personalcommunication networks (PCN's) with prioritized handoff procedures

Evaluates four handoff priority-oriented channel allocation schemes. These give priority to handoff calls by reserving channels exclusively for handoff calls. The measurement-based handover channel adaptive reassignment scheme (MHAR-A) exclusively uses reserved handover channels for newly originated calls if a certain criterion is satisfied. All four schemes studied differ from the conventional guard channel-based handover priority-oriented channel allocation scheme. To study the schemes, a personal communication network (PCN) based on city street microcells is considered. A teletraffic simulation model accommodating a fast moving vehicle is developed, and the performance parameters are obtained. The performances of all four schemes are compared with the nonpriority scheme and the conventional guard channel-based handover priority-oriented channel allocation scheme. It was found that some of the channel allocation algorithms studied improved the teletraffic capacity over the nonpriority and the conventional guard case. Also, the probability of new call blocking and carried traffic was improved for three of the schemes when compared to the conventional guard scheme. The MHAR-A scheme did not perform up to expectation. Nevertheless, it can be used to finely control the communication service quality equivalent to the control obtained by varying the number of handoff channels in a fraction of one. Increasing the number of reserved handover channels in fraction of one can never be achieved in the conventional guard channel-based handover priority-oriented channel allocation scheme     

Handover and dynamic channel allocation techniques in mobilecellular networks

This paper deals with an efficient dynamic channel allocation (DCA) technique applicable to terrestrial mobile cellular networks. A channel (or resource) is a fixed frequency bandwidth (FDMA), a specific time-slot within a frame (TDMA), or a particular code (CDMA), depending on the multiple access technique used. A cost function has been defined by which the optimum channel to be assigned on demand can be selected. In addition, a suitable mobility model has been derived to determine the effects of handovers on network performance. The performance of the proposed DCA technique has been derived by computer simulations in terms of call blocking and handover failure probabilities. Comparisons with the classical fixed channel allocation (FCA) technique and other dynamic allocation algorithms recently proposed in the literature have been carried out to validate the proposed technique     

A Dynamic Reservation-Based Call Admission Control Algorithm for Wireless Networks Using the Concept of Influence Curve

In this paper a dynamic channel reservation and call admission control scheme is proposed to provide QoS guarantees in a mobile wireless network using the concept of influence curve. The basic idea behind the proposed scheme is that a moving user, in addition to its requirements in the current cell, exerts some influence on the channel allocation in neighboring cells. Such an influence is related to the moving pattern of the users and is calculated statistically. Furthermore we developed a general analytical model to calculate the corresponding blocking probabilities for wireless networks with multiple platforms, which removes the commonly used assumption that new calls and handoff calls have same channel holding time. The numerical results demonstrate that our scheme outperforms traditional channel reservation schemes and can effectively adapt to the real time network conditions.     

基于优先级信道预留的快速动态信道分配算法

针对TD-SCDMA系统现有快速动态信道分配算法的不足,提出了一种基于优先级信道预留的快速动态信道分配算法.该算法根据接力切换用户的移动台属性设定不同的优先级,为接力切换呼叫预留信道,结合小分组借用算法,增加了可移动边界动态信道分配(MB DCA)策略的灵活性.仿真结果表明,此算法相对于混合数据速率、小分组借用(MRG,mixed-data rate grouping borrowed)MB DCA算法,实现了VIP和快速移动切换用户的优先接入,有效地降低了切换呼叫的阻塞率,提高了数据业务性能和系统的信道利用率.     

A mathematical model for wireless channel allocation and handoff schemes

A mathematical model for analytical study on complete and partial channel allocation schemes is presented in this paper. Expression for the queue length distribution has been analytically derived. The mathematical model can be used for analysis of multiple call categories like new calls, handoff calls, delay tolerant or delay sensitive calls. This adaptive mathematical model can be utilized to design optimal channel allocation algorithms, or even test the already established resource allocation schemes for provisioning of Quality-of-Service to enable the usage of real time mobile applications. Most existing studies depend upon simulation experiments to investigate the performance of their proposed algorithms, but the mathematical model presented here can really help to evaluate such proposals from an analytical perspective.     

Channel Allocation for GPRS with Buffering Mechanisms

General Packet Radio Service (GPRS) provides mobile users end-to-end packet-switched services by sharing the radio channels with voice and circuit-switched services. In such a system, radio resource allocation for circuit-switched and packet-switched services is an important issue, which may affect the QoS for both services significantly. In this paper, we propose two algorithms: Dynamic Resource Allocation with Voice and Packet queues (DRAVP) and Dynamic Resource Allocation with Packet and Voice queues (DRAPV) for channel allocation of the voice calls and packets. We propose analytic and simulation models to investigate the performance of DRAVP and DRAPV in terms of voice call incompletion probability, packet dropping probability, average voice call waiting time, and average packet waiting time. Our study indicates that the buffering mechanism for GPRS packets significantly increase the acceptance rate of GPRS packets at the cost of slightly degrading the performance of voice calls.     

Resource Allo cation in High Energy-E? cient Co op erative Sp ectrum Sharing Communication Networks

High energy-e?cient wireless communica-tion has become hot due to global low-carbon economy. The systems total transmitting power can be saved by resource allocation in cooperative spectrum sharing net-works. In cooperative spectrum sharing, the secondary user relays the primary users tra?c, as a return, the sec-ondary user is admitted to access the licensed spectrum for its own data transmission. An optimal power and time al-location are presented to minimize the overall energy con-sum ption with the users service quality guaranteed in co-operative spectrum sharing. We formulated it as a convex problem and achieve its optimal power and time allocation in closed form. We analyze the performance of two different transmission protocols for the single relay channel.