Approximation of performance measures in cellular mobile networks with dynamic channel allocation

This paper considers large cellular mobile networks with dynamic channel allocation in which the arrival rates, holding times and handover probabilities for the different cells are identical. Such networks could model, for example, cellular networks in suburban areas. Different methods of analysing these networks are compared. These methods fall into two basic categories, those which approximate a network with a smaller finite network and those which consider the expected performance of a cell within an environment consisting of cells with identical properties. Simplifications of these methods which arise out of the reversibility of a symmetric cellular network are also discussed.     

蜂窝通信网络中的分布式无线信道分配方法

文中提出了一种适用于蜂窝通信网的分布式无线信道分配方法。当网络部署环境中出现干扰后,终端用户通过控制信道,发送反馈信息至基站;基站接收到反馈信息后,对可用信道进行扫频,利用广播帧通知受干扰的终端用户可用信道信息;然后终端用户收到基站发送的广播帧后,根据优先级机制,选择新的信道重新建立与基站的通信,当蜂窝通信网中终端用户受外部干扰而信道中断后,该方法可减少终端用户和基站之间信令的开销。     

Distributed fault-tolerant channel allocation for cellular networks

A channel allocation algorithm includes channel acquisition and channel selection algorithms. Most of the previous work concentrates on the channel selection algorithm since early channel acquisition algorithms are centralized and rely on a mobile switching center (MSC) to accomplish channel acquisition. Distributed channel acquisition algorithms have received considerable attention due to their high reliability and scalability. However, in these algorithms, a borrower needs to consult with its interference neighbors in order to borrow a channel. Thus, the borrower fails to borrow channels when it cannot communicate with any interference neighbor. In real-life networks, under heavy traffic load, a cell has a large probability to experience an intermittent network congestion or even a communication link failure. In existing distributed algorithms, since a cell has to consult with a large number of interference neighbors to borrow a channel, the failure rate will be much higher under heavy traffic load. Therefore, previous distributed channel allocation algorithms are not suitable for real-life networks. We first propose a fault-tolerant channel acquisition algorithm which tolerates communication link failures and node (MH or MSS) failures. Then, we present a channel selection algorithm and integrate it into the distributed acquisition algorithm. Detailed simulation experiments are carried out in order to evaluate our proposed methodology. Simulation results show that our algorithm significantly reduces the failure rate under network congestion, communication link failures, and node failures compared to nonfault-tolerant channel allocation algorithms. Moreover, our algorithm has low message overhead compared to known distributed channel allocation algorithms, and outperforms them in terms of failure rate under uniform as well as nonuniform traffic distribution     

Performance analysis of A dynamic channel allocation technique for satellite mobile cellular networks

This paper deals with an efficient dynamic channel allocation (DCA) technique suitable for applications in mobile satellite cellular networks. A cost function is defined to allow an optimum selection of channels to be allocated on demand. A mobility model suitable for low earth orbit (LEO) satellite systems is presented. The performance of the novel DCA technique in terms of call blocking probability has been derived by simulations. The obtained results are compared with those achieved by a fixed channel allocation (FCA) technique to show a better behaviour.     

Performance analysis of channelized cellular systems with dynamic channel allocation

We present an analytical model to compute the blocking probability in channelized cellular systems with dynamic channel allocation. We model the channel occupancy in a cell by a two-dimensional (2D) Markov chain, which can be solved to obtain the blocking probability in each cell. We apply our analytical model to linear highway systems with and without lognormal shadowing and then extend it to 2D cellular systems with lognormal shadowing. We show that, for linear highway systems, distributed dynamic channel-allocation schemes perform similarly to the centralized dynamic channel-allocation schemes in terms of blocking probability. However, for 2D cellular systems, the improvement in the performance is significant and the reduction in the blocking probability in systems with distributed dynamic channel allocation is by almost one order of magnitude, when compared to that in systems with centralized dynamic channel allocation. In practice, our analysis of linear highway systems is applicable to Digital European Cordless Telephony (DECT) and that of 2D cellular systems is applicable to global systems for mobile communications (GSM).     

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     

Capacity allocation and channel assignment in cellular radio systems using reuse partitioning

Reuse partitioning is a technique for providing more efficient spectrum reuse in cellular radio systems. A cell in such a system is divided into concentric zones, each associated with an overlaid cell plan. For these schemes an optimum channel assignment strategy is proposed. Numeric examples show capacity improvements of about 50% compared to conventional systems.<>     

Efficient dynamic channel allocation techniques with handoverqueuing for mobile satellite networks

Efficient dynamic channel allocation techniques with handover queuing suitable for applications in mobile satellite cellular networks, are discussed. The channel assignment on demand is performed on the basis of the evaluation of a suitable cost function. Geostationary and low Earth orbit (LEO) satellites have been considered. In order to highlight the better performance of the dynamic techniques proposed, a performance comparison with a classical fixed channel allocation (FCA) has been carried out, as regards the probability that a newly arriving call is not completely served. It has also been shown that a higher traffic density, with respect to GEO systems, is manageable by means of LEO satellites     

An efficient fault-tolerant distributed channel allocation algorithm for cellular networks

A channel allocation algorithm in a cellular network consists of two parts: a channel acquisition algorithm and a channel selection algorithm. Some of the previous works in this field focused on centralized approaches to allocating channels. But, centralized approaches are neither scalable nor reliable. Recently, distributed dynamic channel allocation algorithms have been proposed, and they have gained a lot of attention due to their high reliability and scalability. But, in most of the algorithms, the cell that wants to borrow a channel has to wait for replies from all its interference neighbors and, hence, is not fault-tolerant. In this paper, we propose a new algorithm that is fault-tolerant and makes full use of the available channels. It can tolerate the failure of mobile nodes as well as static nodes without any significant degradation in service.     

Energy efficiency in wireless cellular networks based on dynamic power allocation

Energy efficiency is increasingly vital for wireless cellular systems due to the limited battery resources of mobile clients. Among previous work, many studies suggest different methods to reduce the transmission power in case of a fixed condition. However, according to the mobility of users and continuous variation of cellular network environment, the traffic load of base station (BS) and the channel state information (CSI) are varying. In this paper, we proposed a dynamic power allocation schedule to assign transmit power to mobile users in the downlink, resulting in optimal energy saving. The novel power allocation scheme was based on the coordination of neighbouring cells. The results showed that the scheme dramatically reduce the average bit error rate (BER) and total tranmitted power of the system, with the improvement of network capacity.     

蜂窝网络中信道分配模型的优化设计与实现

基于基站功率控制的传统信道资源分配模型,采用的帧结构中的两跳链路处于同一时隙中,不能在一帧中完成链路的数据传递,导致系统信道资源分配业务传递滞后。提出基于资源复用的蜂窝网络信道资源分配模型,蜂窝网络采用帧结构向这些通信链路分配时频资源,通过资源复用形式降低蜂窝网络的信道分配资源消耗,在一帧中实现两跳链路的信道分配数据传递。依据扰动的Greedy算法思想,按照带有扰动的信道质量矩阵,实现蜂窝网络信道分配。处于同扇区的两个中继节点间通过动态资源分配方法,按照小区信道的业务情况动态分配信道资源。通过仿真实验分析对比信道分配需求量、阻塞率、收敛性、网络吞吐量、网络节点间通信中断概率五项指标。仿真结果表明,所设计蜂窝网络信道分配模型在对蜂窝网络信道资源进行信道分配过程中,信道资源的使用率增强,分配资源消耗低,信道分配质量提高,具有较高的业务实时性。     

Comparison of two novel heuristic dynamic channel allocation techniques in cellular systems

Dynamic channel assignment (DCA) has been discussed in the literature as a way to achieve improved resource management in cellular networks. In the simplest dynamic allocation scheme, all channels are kept in a central pool and are used on a call-by-call basis. DCA is therefore a complex real time operation and various heuristic methods have been devised as mechanisms to give a fast and reliable solution to this problem. This paper examines the implementation of a DCA model using two approaches from the field of evolutionary computation. The first is the so called genetic algorithm (GA) and the second is the combinatorial evolution strategy (CES). Computer simulations evaluate and compare these proposed heuristic DCA schemes concerning their application to a cellular model for both uniform and non-uniform traffic load conditions. © 1998 John Wiley & Sons, Ltd.     

Bio-inspired power control and channel allocation for cellular networks with D2D communications

With the tremendous increment of traffic in the next generation mobile networks, device to device (D2D) communication is proposed to relieve the traffic burden of the base station and improve the overall network capacity. It supports direct communications between devices and could reuse the resources of cellular users (CUs). Despite the advantages, D2D communications bring great challenges in interference management. In this paper, we study the power control and channel allocation problems in three scenarios: (1) one CU and one D2D pair; (2) one CU and multiple D2D pairs; (3) multiple CUs and multiple D2D pairs. The goal is to coordinate the mutual interferences and maximize the overall network capacity. We derive sufficient conditions to guarantee the efficiency of D2D communications in scenarios with one CU and one D2D pair. We propose the bio-inspired PSO-P power control algorithm for the scenarios with one CU and multiple D2D pairs, and the PSO-CP algorithm for the scenarios with multiple CUs and multiple D2D pairs to jointly assign channels and powers. Simulation results show that the proposed algorithms are efficient in improving the overall network capacity.

     

A dynamic channel assignment scheme for clustered multihop cellular networks

Whereas cellular systems have traditionally adopted single‐hop transmissions between the mobile station (MS) and the base station (BS), researchers expect multihop transmission to be utilised in the future. Cellular systems present several challenges, such as channel assignment, which are exacerbated by multimedia service traffic and an increasing number of subscribers. Recently, a clustered multihop cellular network (cMCN) architecture that complements traditional cellular systems has been proposed and studied using fixed channel assignment (FCA). However, the performance of FCA is limited when the traffic pattern varies in a service area. This paper proposes the use of dedicated information ports (DIPs) as clusterheads in cMCN, followed by a multihop dynamic channel assignment (mDCA) scheme. The mDCA works by assigning channels based on information about interference in surrounding cells. Two different channel searching strategies are developed and evaluated. Through computer simulation, we show that the proposed mDCA is able to achieve a significantly improved capacity which is maintained when the number of system channels is increased. Finally, issues regarding the implementation of the mDCA and future work on this topic are discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Dynamic channel partitioning with flexible channel combination for TDMA-based cellular systems

In this paper, we propose flexible dynamic channel partitioning (FDCP) with a flexible channel-combination scheme to support multiple services. CP is based on the idea that different services may require different signal-to-interference ratios (SIRs), and thus, different reuse factors. In FDCP, different services are allocated to the channels depending on the reuse factors they require. FDCP tries to minimize the effect of the assigned channels on the channel availability to the interfering cells and to reduce the overall reuse distances of the systems.     

蜂窝网络中D2D通信模式选择和信道分配算法

设备到设备(D2D)通信中,不合理的模式选择和信道分配方案会引入干扰,严重时不仅不能体现D2D通信优势,而且还将导致蜂窝用户传输速率下降。针对这一问题,文章提出了一种蜂窝网络中D2D模式选择和信道分配算法。仿真结果表明,新算法能够在有效的平衡蜂窝网络中D2D用户接入率和系统总吞吐量的同时,最小化用户之间的干扰。     

On the performance and fairness of dynamic channel allocation in wireless mesh networks

Channel assignment in multichannel multiradio wireless mesh networks is a powerful resource management tool to exploit available multiple channels. Channels can be allocated either statically on the basis of long‐term steady state behavior of traffic or dynamically according to actual traffic demands. It is a common belief that dynamic schemes provide better performance; however, these two broad classes of channel allocation schemes have not been compared in detail. In this paper, we quantify the achievable performance gain and fairness improvement through an optimal dynamic channel allocation scheme. We develop optimal algorithms for a dynamic and three static schemes using mixed integer linear programming and compare them in the context of QoS provisioning, where network performance is measured in terms of acceptance rate of QoS sensitive traffic demands. Our extensive simulations show that static schemes should optimize channel allocation for long‐term traffic pattern and maintain max–min fairness to achieve acceptable performances. Although the dynamic and max–min fair static schemes accomplish the same fairness, the dynamic channel allocation outperforms the static scheme about 10% in most cases. In heavily overloaded regimes, especially when network resources are scarce, both have comparable performances, and the max–min fair scheme is preferred because it incurs less overhead. Copyright © 2011 John Wiley & Sons, Ltd.     

Power control and channel allocation for real‐time applications in cellular networks

The next‐generation packet‐based wireless cellular network will provide real‐time services for delay‐sensitive applications. To make the next‐generation cellular network successful, it is critical that the network utilizes the resource efficiently while satisfying quality of service (QoS) requirements of real‐time users. In this paper, we consider the problem of power control and dynamic channel allocation for the downlink of a multi‐channel, multi‐user wireless cellular network. We assume that the transmitter (the base‐station) has the perfect knowledge of the channel gain. At each transmission slot, a scheduler allots the transmission power and channel access for all the users based on the instantaneous channel gains and QoS requirements of users. We propose three schemes for power control and dynamic channel allocation, which utilize multi‐user diversity and frequency diversity. Our results show that compared to the benchmark scheme, which does not utilize multi‐user diversity and power control, our proposed schemes substantially reduce the resource usage while explicitly guaranteeing the users' QoS requirements. Copyright © 2007 John Wiley & Sons, Ltd.     

Bounding the performance of dynamic channel allocation with QoSprovisioning for distributed admission control in wireless networks

We investigate the performance of distributed admission control with quality of service (QoS) provisioning and dynamical channel allocation for mobile/wireless networks where the co-channel reuse distance is considered as the only limiting factor to channel sharing. We first provide a QoS metric feasible for admission control with dynamically allocated channels. We then derive a criterion analytically using the QoS measure for distributed call admission control with dynamic channel allocation (DCA). When maximum packing is used as the DCA scheme, the results obtained are independent of any particular algorithm that implements dynamic channel assignments. Our results, thereby, provide the optimal performance achievable for the distributed admission control with the QoS provisioning by the best DCA scheme in the given setting