Virtual partitioning resource allocation for multiclass traffic in cellular systems with QoS constraints

Resource allocation is a vital component of call-admission control that determines the amount of resource to assign to new and handoff connections for quality-of-service (QoS) satisfaction. In this paper, we present approximate analytical formulations of virtual partitioning resource-allocation schemes for handling multiclass services with guard channels in a cellular system. Resource-allocation models for best effort and guarantee access with preemption for best effort traffic and virtual partition with preemption for all classes are investigated. The analytical models, derived using a K-dimensional Markov chain, are solved using preemption rules for these schemes. Call-level grade of service, such as new-call-blocking probability, handoff-call-blocking probability, and system utilization, and packet-level QoS, such as packet-loss probability, are used as performance metrics. The performances of fast and slow mobile users are evaluated analytically and by simulation. The analytical and simulation results show excellent agreement. A method to maximize system utilization through joint optimization of call-/packet-level parameters is proposed. Numerical results indicate that significant gain in system utilization is achieved.     

Spectrum resource allocation for wireless packet access withapplication to advanced cellular Internet service

The advanced cellular Internet service (ACIS) is targeted for applications such as Web browsing with a peak downlink transmission rate on the order of 1-2 Mbits/s using a wide-area cellular infrastructure. In order to provide bandwidth on demand using scarce radio spectrum, the medium-access control (MAC) protocol must: 1) handle dynamic and diverse traffic with high throughput, and 2) efficiently reuse limited spectrum with high peak rates and good quality. Most of the existing approaches do not sufficiently address the second aspect. This paper proposes a dynamic packet assignment (DPA) scheme which, without coordinating base stations, allocates spectrum on demand with no collisions and low interference to provide high downlink throughput. Interference sensing and priority ordering are employed to reduce interference probability. A staggered frame assignment schedule is also proposed to prevent adjacent base stations from allocating the same channel to multiple mobiles at the same time. Simulation results based on a packet data traffic model derived from wide-area network traffic statistics, which exhibit a “self-similar” property when aggregating multiple sources, confirm that this method is able to reuse spectrum efficiently in a large cellular system having many users with short active periods. Distributed iterative power control further enhances spectrum efficiency such that the same channel can be simultaneously reused in every base station     

An efficient radio resource management strategy for adaptive OFDM cellular systems

This paper presents an efficient Radio Resource Management （RRM） strategy for adaptive Orthogonal Frequency Division Multiplexing （OFDM） cellular systems. In the proposed strategy, only those users who have the same distance from their base stations can reuse a same subcarrier. This can guarantee the received Carrier-to-Interference ratio （C/I） of each subcarrier to be acceptable as required by system planning. Then by employing different modulation scheme on each subcarrier according to its received C/I, system spectral efficiency can be gracefully increased. Analytical and simulation results show that the spectral efficiency is improved by 40% without sacrificing the Bit Error Rate （BER） performance and call blocking probability and system capacity of the proposed strategy is better than conventional systems.     

Application of narrow-beam antennas and fractional loading factorin cellular communication systems

It is well known that cellular system capacity can be increased by reducing the cell cluster size N. Reducing the cluster size, however, increases cochannel interference. In the literature, several techniques have been proposed for controlling the cochannel interference and simultaneously reducing the cluster size. In this paper, we combine two proposed capacity improvement methods and explore the effectiveness of reducing cochannel interference using narrow-beam antennas (“smart antennas”) with the fractional loading factor. As shown in this paper, it is possible to increase capacity by many times by decreasing the cluster size (i.e. increasing frequency reuse), although the proper combination of antenna specifications and fractional loading is surprisingly nonintuitive. The first cochannel mitigation technique uses base-station antennas with narrow beams in the direction of the desired mobile stations and significant side lobe attenuation in the direction of undesired users. The second technique exploits the fact that interference is related to the loading factor p_ch, which defines the probability that a given channel is in use within a cell, We show that large capacity gains with respect to a reference cellular system (N=7, three sectors per cell) can be obtained by combining these two techniques. This paper provides insight for system-level deployment of high-capacity cellular systems and can be extended to fixed wireless systems as well     

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     

基于天线波束成形的OFDMA系统的自适应资源分配

对正交频分复用接入系统在多用户多天线传输情况下的自适应资源分配策略进行了研究,提出了一种基于天线波束成形的,包括动态子载波分配、自适应调制、比特加载的无线资源分配方案.算法的优化设计目标是在满足总的恒定传输比特数和误比特率性能要求的情况下,使得系统总的发射功率最小.仿真结果表明,由于多天线阵列增益和多用户分集增益,系统整体性能得到了明显的优化.     

Fairness based resource allocation for multiuser MISO-OFDMA systems with beamforming

Resource allocation problem in multiuser multiple input single output-orthogonal frequency division multiple access (MISO-OFDMA) systems with downlink beamforming for frequency selective fading channels is studied. The article aims at maximizing system throughput with the constraints of total power and bit error rate (BER) while supporting fairness among users. The downlink proportional fairness (PF) scheduling problem is reformulated as a maximization of the sum of logarithmic user data rate. From necessary conditions on optimality obtained analytically by Karush-Kuhn-Tucker (KKT) condition, an efficient user selection and resource allocation algorithm is proposed. The computer simulations reveal that the proposed algorithm achieves tradeoff between system throughput and fairness among users.     

Suboptimal resource allocation with MMSE detector for grouped MC-CDMA systems

This article puts forward two novel user-grouping algorithms for grouped multi-carrier （MC）-code division multiple access （CDMA） systems. As is well known, the adaptive assignment for user-grouping plays an important role for link quality of multi-access transmissions. In the study, the capacity-maximizing problem of user-grouping is formulated. By using the Kuhn-Tucker condition, the optimal criterion is deduced and found to have a similar form with signal to noise plus interference （SINR）. However SINR includes the signal power that can only be determined after user-grouping. Therefore the optimal criterion will lead to an impractical application. To deal with it, the user＇s equivalent SINR for minimum mean square error （MMSE） detector is proposed and served as a suboptimal assignment criterion, based on which two kinds of user-grouping algorithms are proposed. In the algorithms, only partial channel information is needed at the base station, which saves a large part of the bandwidth occupied by feedback information. Computer simulations have evaluated an excellent performance of the proposed algorithms at both link quality and data rate. Meanwhile, the proposed algorithms have lower implementation complexity for practical reality.     

An efficient resource allocation scheme in a dense RFID network based on cellular learning automata

Radio‐frequency identification (RFID) is a wireless communication technology. Radio frequencies can cause interference in a dense RFID system, thus decreasing efficiency. In recent years, many protocols have been proposed to reduce reader collisions based on multiple‐access techniques. The main weakness of Time Division Multiple Access (TDMA)‐based schemes is the random selection of resources. Additionally, they do not consider the distance between the interfering readers. Therefore, the likelihood of interference in an RFID system will be increased. To address this problem, we propose a new scheme for allocating resources to readers using a learning technique. The proposed scheme takes into account the distance between interfering readers, and these readers acquire the necessary knowledge to select new resources based on the results of the previous selection of neighboring readers using cellular learning automata. This approach leads to reduced interference in an RFID system. The proposed scheme is fully distributed and operates without hardware redundancy. In this scheme, the readers select new resources without exchanging information with each other. The simulation results show that the percentage of kicked readers decreased by more than 20%, and the proposed scheme also provides higher throughput than do state‐of‐the‐art schemes for dense reader environments and leads to further recognition of tags.     

Fairness based resource allocation for uplink OFDMA systems

This article investigates two fairness criteria with regard to adaptive resource allocation for uplink orthogonal frequency division multiple access （OFDMA） systems. Nash bargaining solution （NBS） fairness and proportional fairness （PF） are two suitable candidates for fairness consideration, and both can provide attractive trade-offs between total throughput and each user＇s capacity. Utilizing Karush-Kuhn- Tucker （KKT） condition and iterative method, two effective algorithms are designed, to achieve NBS fairness and proportional fairness, respectively. Simulation results show that the proposed resource allocation algorithms achieve good tradeoff between the overall rate and fairness, with little performance loss from the total capacity.     

一种MIMO系统中的新型资源分配算法

本文提出了一种MIMO(Multi-Input and Multi-Output)系统中的新型自适应调制和功率分配算法,在奇异值分解的基础上通过注水算法进行功率分配,此后根据所分配的功率与信道状态信息来确定自适应调制的门限及相应的调制阶数,并在自适应调制后通过功率修正因子来弥补常见算法中功率不能得到有效利用的问题,仿真结果表明该算法可以得到较高的频谱效率.     

AF中继下行链路系统的能效资源分配方案

为最大化放大转发中继系统的下行链路总能效,结合系统的电路功率,提出了一种基于能效的中继选择和功率分配联合方案.为降低复杂度,采用分步式次优化方案,利用虚拟直传信道增益得到中继选择方法,并将中继系统转换为单跳系统;然后利用凸规划得到最优功率分配.此外,为适应不同的用户分布,提出联合小区呼吸机制的分配方案.仿真结果表明,所提次优联合方案逼近最优值,联合小区呼吸的方案可适应不同的用户分布并进一步提升能效.     

Radio resource index for WCDMA cellular systems

In this letter, a radio resource index (RRI) is derived to estimate the radio resources of a connection in WCDMA cellular systems. An analytical model is presented and large deviation techniques are used. The RRI can transform traffic parameters and multiple quality-of-service (QoS) requirements into a measure of radio resources using a unified metric.     

Time-based resource allocation for downlink in heterogeneous wireless cellular networks

Telecommunication Systems - Heterogeneous Wireless Cellular Networks (HWCNs) are an essential part of current and future cellular networks as a result of several benefits they offer regarding the...     

超密集异构蜂窝网多维资源联合优化算法

作为5G的关键技术,超密集组网(UDN)可以大幅度提高网络容量和用户体验,但其性能严重受限于小区间干扰。针对超密集异构蜂窝网络的无线资源高效管理问题,提出了一种多维无线资源联合分配算法。为了在保障用户服务质量的前提下,最大化系统能效,将时频资源与功率资源的最优分配问题建模为有约束的组合优化问题。由于这是一个NP-hard问题,求解比较困难。因此,采用分步优化+迭代搜索策略：首先基于模拟退火算法进行时频资源优化分配,并引入粒子删减和回火升温过程以提高搜索速度和避免落入局部最优陷阱;然后采用拉格朗日乘子法进行功率最优分配;最后,通过多次迭代,逼近全局最优解。仿真结果表明,提出的联合资源分配算法能够保障用户间的公平性并且有效提高系统能效与网络吞吐量,同时具有更快的收敛速度和更高的收敛精确度。     

Analysis of resource allocation with macroscopic diversity for uplink OFDMA systems

This paper describes a framework of link capacity analysis for interference mitigation of uplink Orthogonal Frequency Division Multiple Access systems. A Macroscopic Diversity Oriented Resource Allocation (MDORA) is performed via inter-cell coordination based on the location of Mobile Stations (MSs) by exploiting macroscopic diversity in the uplink transmission. In the numerical analysis, the Inter-Cell Interference is derived as a closed form over a multi-cell environment. Subsequent numerical results demonstrate that MDORA offers an efficient inter-cell interference mitigation and a throughput expansion. Moreover, when up-link sectorization is adopted, the MDORA scheme presents a lower inter-cell interference, a reduced outage probability and an improved throughput.     

Power‐efficient resource allocation with QoS guarantees for TDMA fading channels

This paper proposes two power‐efficient resource allocation policies with statistical delay Quality of Service (QoS) guarantees for uplink time‐division multiple access (TDMA) communication links. Specifically, the first policy aims at maximizing the system throughput while fulfilling the delay QoS and average power constraints, and the second policy is devised as an effort to minimize the total average power subject to individual delay QoS constraints. Convex optimization problems associated with the resource allocation policies are formulated based on a cross‐layer framework, where the queue at the data link layer is served by the resource allocation policy. By employing the Lagrangian duality theory and the dual decomposition theory, two subgradient iteration algorithms are developed to obtain the globally optimal solutions. The aforementioned resource allocation policies have been shown to be deterministic functions of delay QoS requirements and channel fading states. Moreover, numerical results are provided to demonstrate the performance of the proposed resource allocation policies. Copyright © 2010 John Wiley & Sons, Ltd.     

An optimal energy resource allocation framework for cellular networks with power grid interruptions

Wireless Networks - In this paper, we investigate the problem of optimal allocation of renewable energy resources to power base stations (BSs) in cellular networks while accounting for possible...     

An optimization technique for efficient channel allocation in cellular network

For today’s wireless mobile communication systems, efficient use of limited radio spectrum with minimum interferences is required. Itinvestigates an Optimal Genetic Algorithm approach (GA) for Hybrid Channel allocation (NP hard) focusing on reduction in interference in cellular Network. Obtained an interference graph based fitness function to enhance the performance of HCA for interference reduction. It is shown that the use of integer genetic representation for Crossover and mutation operation enhances the speed of GA leading to less computation time. Comparison of proposed method is done with reported literature for KUNZ 4 which results in less co-channel and co-site interference depicted by interfering edges and also number of generations required are less. The result for KUNZ 1, KUNZ 2 and KUNZ 3 are obtained with minimum interference along with computation time.     

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.