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31.
32.
Minjoong Rim 《International Journal of Communication Systems》2011,24(4):526-531
While conventional frequency reuse techniques need to allocate mutually exclusive frequency resources to adjacent cells, this paper proposes a technique for OFDMA systems to use pseudo‐random subchannel allocation patterns based on the preamble number. Although sophisticated cell planning is not required for the proposed technique, irregular frequency patterns can allow efficient interference avoidance and high data throughput. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
33.
Hiep H. Nguyen Suk‐Hwan Lee Won‐Joo Hwang 《International Journal of Communication Systems》2015,28(14):2020-2034
Because energy efficiency (EE) is inevitable in future wireless cellular networks, in this paper, we focus on improving the number of bits delivered to users for each unit energy consumption in the downlink of orthogonal frequency‐division multiple access cellular networks with base stations (BSs) coordination. Specifically, each BS shares the channel qualities of users with others and jointly choose the set of co‐channel users and the transmit power allocated to maximize the EE of the system subject to the transmit power ceiling of each BS and minimum required data rate. We formulate the problem as a nonlinear fractional optimization problem, using nonlinear fractional programming, the original hard‐to‐solve problem is transferred to a new one that has the same optimal solution and is easier to solve, this enables two iterative algorithms that achieve nearly the same maximum EE. Numerical results are provided to show the convergence and superiority of the two proposed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
34.
In this paper, we propose a novel uplink power control algorithm, SMST, for multiple-input multiple-output orthogonal frequency-division multiple access (MIMO-OFDMA).We perform an extensive system-level simulation to compare different uplink power control algorithms, including the FPC adopted in 3GPP LTE and LTE-Advanced. Simulations show that SMST adopted in IEEE 802.16m outperforms other algorithms in terms of spectral efficiency, cell-edge performance, interference control, and trade-off control between sector-accumulated throughput and cell-edge user throughput. The SMST performance gain over FPC can be more than 40%. 相似文献
35.
Resource allocation in orthogonal frequency division multiple access‐based cognitive radio systems with minimum rate constraints 下载免费PDF全文
Li Li Changqing Xu Pingzhi Fan Jian He 《International Journal of Communication Systems》2014,27(8):1147-1159
In this paper, resource allocation problem in orthogonal frequency division multiple access‐based cognitive radio (CR) systems to maintain minimum transmission rate constraints of CR users (CRUs) with the specified interference thresholds is investigated. Firstly, a single primary user (PU) CR system is considered, and a suboptimal resource allocation algorithm to maximize the sum transmission rate of all CRUs is proposed. Secondly, the single‐PU scenario is extended to multiple‐PU case, and an asymptotically optimal resource allocation algorithm is proposed using dual methods subject to constraints on both interference thresholds of PUs and total transmit power of all CRUs. Analysis and numerical results show that, in contrast to classical resource allocation algorithms, the proposed algorithm can achieve higher transmission rate and guarantee each CRU's minimum transmission rate in both scenarios. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
36.
Rate adaptive resource allocation in orthogonal frequency division multiple access system using multi‐objective immune algorithm 下载免费PDF全文
Chai Zheng‐Yi Zhu Si‐Feng Shen Lian‐Feng 《International Journal of Communication Systems》2014,27(11):3255-3265
Rate adaptive downlink resource allocation in orthogonal frequency division multiple access system is a constraint optimization problem, which is to maximize the minimum data rate of the user subject to constraint that total power cannot exceed a given value. How to handle the constraint is a key issue for constrained optimization problem. Different with the available schemes on constraint handling, the proposed algorithm converts the constraint into an objective. Then, the resource allocation is combined into a multi‐objective optimization problem. An improved multi‐objective optimization algorithm based on artificial immune system is proposed to solve it. The simulation results show that, compared with previous schemes, the proposed algorithm performs remarkable improvement in sum capacity. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
37.
在2009年10月ITU-R WP5D#6的会议上,IEEE 802.16m作为IMT-Advanced候选提案提交ITU。本文对IEEE802.16m候选方案的主要技术特点、性能评估进行介绍。 相似文献
38.
OFDMA及其在IEEE802.16-2005中的应用 总被引:1,自引:0,他引:1
正交频分多址(OFDMA)是以正交频分复用(OFDM)调制为基础的新一代多址技术,具有很高的带宽利用率。文章介绍了它的基本原理,然后简单介绍了它在移动宽带无线接入中的应用,主要是关于信道编码,链路自适应技术,多天线技术。 相似文献
39.
Marc C. Necker 《Mobile Networks and Applications》2009,14(4):539-550
The currently emerging 802.16e (WiMAX) and 3GPP Long Term Evolution (LTE) cellular systems are based on Orthogonal Frequency
Division Multiple Access (OFDMA). OFDMA suffers from heavy inter-cell interference if neighboring base stations use the same
frequency range. One approach to solve this issue is the application of beamforming antennas in combination with interference
coordination (IFCO) mechanisms between base stations. In this paper, we trace the problem of IFCO back to the graph coloring
problem and investigate the achievable resource utilization of the interference coordinated system. We develop a heuristic
that allows the combination of arbitrary scheduling algorithms with the IFCO mechanism. This allows an efficient utilization
of the radio system’s frequency resources while still obeying scheduling constraints, such as Quality of Service requirements.
Finally, we study the tradeoff between fairness and the total system throughput.
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Marc C. NeckerEmail: |
40.
Daniele Tarchi Romano Fantacci Emanuele Bonciani 《Wireless Communications and Mobile Computing》2010,10(7):888-898
In the last few years the wireless metropolitan area networks (WMANs) have increased their popularity and attracted the interest of important research groups all over the world; as a consequence, several standards have been proposed. Among them, the IEEE 802.16 (WiMAX) is one of the most promising standard to carry out a full‐service broadband wireless network in an urban and suburban area. This standard provides high data rate within a wide coverage area with low implementation costs, possibility of multi‐traffic communications, and different network topologies. This paper deals with the analysis and performance comparison of different scheduling techniques for WiMAX networks for allowing quality of service (QoS) differentiation when different types of applications have to be supported and achieving a fair distribution of resource among users. In particular, the focus here is on the resource allocation problem for the case of mobile stations (MSs) active in an urban environment. The proposed scheduling algorithms exploit the orthogonal frequency division multiple access (OFDMA) scheme with adaptive modulation techniques in order to achieve a better network behavior. The performance of the proposed approaches will be derived here by means of theoretical analysis and computer simulations. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献