协同OFDM通信系统中资源分配技术的研究
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摘要
正交频分复用通信系统是未来LTE以及LTE-A系统必不可少的组成部分。由于其符号内子载波调制灵活、抗衰落能力强、在窄带情况下也能发出大量数据等优点,因此是通信中的关键技术之一。中继协同技术是协同通信中的一项重要技术,它可以在不增加基站和额外频谱的情况下,提升系统总速率,扩大边缘小区的覆盖面,近年来已成为一项研究热点。将OFDM技术和协同技术结合,可以有效抗多径干扰和衰落,利用空间分集提升系统总速率,有效改善系统性能,提升功率利用率,提升通信质量,并能支持多用户不同业务服务质量(QoS)要求。而资源分配是OFDM技术和协同技术结合的研究重点,高效的子载波分配算法和比特加载算法对协同OFDM通信系统的资源分配有着越发重要的研究意义。
本文以协同OFDM通信系统中资源分配技术为研究内容,重点讨论了带有中继节点的协同通信系统和不带中继的多用户协同通信系统的资源分配,并在不同的约束条件下，分别对相应的优化目标进行研究,找出最佳的资源分配方案。
在有中继节点的系统中,针对功率受限模型,本文以最大化系统总速率为目标,讨论了译码转发模式下OFDM的资源分配问题。以各个子载波的信道增益为基础,通过中继选择算法,为各个子载波选择合适的中继节点,计算其等效信道增益。在比特分配中,利用遗传算法,通过选择、交叉、变异、重新插入和迭代等操作,计算出全局最优解,为各个子载波分配比特。仿真结果表明：在带有中继节点的通信系统中,通过增加中继节点,使用合适的中继选择算法,使系统速率大于没有使用中继节点的系统。在中继节点数量相同的情况下,通过引入自适应遗传算法,相比等比特分配算法使系统的总速率和功率利用率得到提高。
在无中继节点的系统中,针对多用户速率成比例且功率受限的模型,以最大化系统总速率为目标,重点研究了OFDM的子载波分配和比特分配,提出了贪婪遗传算法混合的二次分配算法,并与不同资源分配算法进行了对比。仿真表明：在无中继节点的多用户协同通信系统中,本文提出的资源分配算法,在系统总速率上优于传统的遗传算法,并且可以较好的完成速率比例约束,满足多用户的速率要求。在相同误码率的情况下,该分配算法,可使系统中子载波所消耗平均信噪比更低。
OFDM communication systems is the necessary part of LTE and LTE-A systems in the future. It has a lot of advantages, for example, the modulation of subcarriers in the symbol is flexibility, the anti-fading ability is strong and large amounts of data can be sent under the narrow band condition, so OFDM is a key technology in the communication systems. Relay cooperative technology is one of the key technologies in cooperative communication systems. It could improve thetotal system rate and expand the coverage of the edge cell while not need to add base station and more spectrum. Combining OFDM technology and cooperative technology could effectively anti-multipath interference and fading, enhance total systemrate and the communication quality using space diversity, improve the system performances and power utilization, and also could support the difference quality of service requirement. The resource allocation is a hotspot in combining OFDM technology and Cooperative technology, and the efficient subcarrier allocation algorithm and bit loading algorithm of thecooperative OFDM communication system's resource allocation has become increasingly important research significance.
In this thesis, we research the resource allocation techniques of the cooperative OFDM communication systems, and focus on the resource allocation problem of the cooperative communication system with relay nodes and multiuser without relay nodes. Under different constraints, we discuss the corresponding optimization objectives and find the optimal resource allocation scheme.
In the systems with relay nodes, we consider maximizing the total system rate as the goal under the condition that the system model is power limited, and discuss the resource allocation problem of the OFDM systems in Decode-and-Forward (DF) model. Based on channel gain of every subcarrier, we use relay selection algorithm to choose relay node for each subcarrier, and then calculate the equal channel gain. In bit allocation part, Genetic Algorithm (GA) is used. Optimal solution will be gotten, using the strong global search ability of Genetic Algorithm. The simulation result shows that in the communication systems with relay node, using the relay node and appropriate relay selection algorithm, the data rate of the systems with relay node will be higher than the system without relay node. Under the same relay node condition in the power limited systems, compared with the adaptive Genetic Algorithm and the Equal Bit Allocation Algorithm (EBA), the total rate of GA will be higher than that of EBA and the power utilization is also better.
In the systems without relay node, we consider power limited systems with data rate proportional of multi-user, and focus on the subcarrier allocation and bit allocation of OFDM systems. We propose the secondary allocation algorithm mixed greedy and genetic algorithm, and compare with other different resource allocation algorithms. The simulation shows that in the communication systems without relay node, the system's total data rate of proposed algorithm is much better than that of the traditional genetic algorithm, and also could meet the data rate requirement of multi-user data rate proportional. In the bit error ratio, the signal noise ratio (SNR) of the proposed algorithm is smaller than that ofthe genetic algorithm under the same bit error ratio (BER) condition.
本文以协同OFDM通信系统中资源分配技术为研究内容,重点讨论了带有中继节点的协同通信系统和不带中继的多用户协同通信系统的资源分配,并在不同的约束条件下，分别对相应的优化目标进行研究,找出最佳的资源分配方案。
在有中继节点的系统中,针对功率受限模型,本文以最大化系统总速率为目标,讨论了译码转发模式下OFDM的资源分配问题。以各个子载波的信道增益为基础,通过中继选择算法,为各个子载波选择合适的中继节点,计算其等效信道增益。在比特分配中,利用遗传算法,通过选择、交叉、变异、重新插入和迭代等操作,计算出全局最优解,为各个子载波分配比特。仿真结果表明：在带有中继节点的通信系统中,通过增加中继节点,使用合适的中继选择算法,使系统速率大于没有使用中继节点的系统。在中继节点数量相同的情况下,通过引入自适应遗传算法,相比等比特分配算法使系统的总速率和功率利用率得到提高。
在无中继节点的系统中,针对多用户速率成比例且功率受限的模型,以最大化系统总速率为目标,重点研究了OFDM的子载波分配和比特分配,提出了贪婪遗传算法混合的二次分配算法,并与不同资源分配算法进行了对比。仿真表明：在无中继节点的多用户协同通信系统中,本文提出的资源分配算法,在系统总速率上优于传统的遗传算法,并且可以较好的完成速率比例约束,满足多用户的速率要求。在相同误码率的情况下,该分配算法,可使系统中子载波所消耗平均信噪比更低。
OFDM communication systems is the necessary part of LTE and LTE-A systems in the future. It has a lot of advantages, for example, the modulation of subcarriers in the symbol is flexibility, the anti-fading ability is strong and large amounts of data can be sent under the narrow band condition, so OFDM is a key technology in the communication systems. Relay cooperative technology is one of the key technologies in cooperative communication systems. It could improve thetotal system rate and expand the coverage of the edge cell while not need to add base station and more spectrum. Combining OFDM technology and cooperative technology could effectively anti-multipath interference and fading, enhance total systemrate and the communication quality using space diversity, improve the system performances and power utilization, and also could support the difference quality of service requirement. The resource allocation is a hotspot in combining OFDM technology and Cooperative technology, and the efficient subcarrier allocation algorithm and bit loading algorithm of thecooperative OFDM communication system's resource allocation has become increasingly important research significance.
In this thesis, we research the resource allocation techniques of the cooperative OFDM communication systems, and focus on the resource allocation problem of the cooperative communication system with relay nodes and multiuser without relay nodes. Under different constraints, we discuss the corresponding optimization objectives and find the optimal resource allocation scheme.
In the systems with relay nodes, we consider maximizing the total system rate as the goal under the condition that the system model is power limited, and discuss the resource allocation problem of the OFDM systems in Decode-and-Forward (DF) model. Based on channel gain of every subcarrier, we use relay selection algorithm to choose relay node for each subcarrier, and then calculate the equal channel gain. In bit allocation part, Genetic Algorithm (GA) is used. Optimal solution will be gotten, using the strong global search ability of Genetic Algorithm. The simulation result shows that in the communication systems with relay node, using the relay node and appropriate relay selection algorithm, the data rate of the systems with relay node will be higher than the system without relay node. Under the same relay node condition in the power limited systems, compared with the adaptive Genetic Algorithm and the Equal Bit Allocation Algorithm (EBA), the total rate of GA will be higher than that of EBA and the power utilization is also better.
In the systems without relay node, we consider power limited systems with data rate proportional of multi-user, and focus on the subcarrier allocation and bit allocation of OFDM systems. We propose the secondary allocation algorithm mixed greedy and genetic algorithm, and compare with other different resource allocation algorithms. The simulation shows that in the communication systems without relay node, the system's total data rate of proposed algorithm is much better than that of the traditional genetic algorithm, and also could meet the data rate requirement of multi-user data rate proportional. In the bit error ratio, the signal noise ratio (SNR) of the proposed algorithm is smaller than that ofthe genetic algorithm under the same bit error ratio (BER) condition.
引文
[1]卢为党,吴宣利,沙学军等,OFDM固定中继系统中单中继多源用户资源分配方案[J],通信学报,2011(9),26～32。
[2]庾志成,移动互联网的发展现状和发展趋势[J],移动通信,2008(9),22～24。
[3]甘雯昱,分布式无线通信环境中的循环延时分集技术[硕士学位论文],合肥：中国科学技术大学,2009。
[4]Yidong Lang,Dirk Wubben. Efficient Power Allocation for Outage Restricted Asymmetric Distributed MIMO Multi-hop Networks. In:Personal, Indoor and Mobile Radio Communications[C]. Cannes,2008.9:15-20.
[5]杜金玲,VAA小区划分方法研究[硕士学位论文],成都：电子科技大学,2009。
[6]LI Xiao, JIN Shi, GAO XiQi. Multi-user MIMO downlink eigen-mode transmission over jointly correlated MIMO channels[J]. Science ChinaInformation Sciences,2011(10),2124-2137.
[7]Rui Yin, Yu Zhang,Guanding Yu,Zhaoyang Zhang. Centralized and distributed resource allocation in OFDM based multi-relay system[J]. Journal of Zhejiang University-Science,2010(6)450-464.
[8]冯子豪,无线协同通信中的网络编码与中继选择[硕士学位论文],南京：南京邮电大学,2011。
[9]Edward C, van der Meulen. Transmission of Information in a T-terminalDiscre-te Memoryless Channel[M]. Los Angeles:University of California,1968.
[10]林威,无线通信中协同分集的性能分析与编码技术研究[硕士学位论文],成都：电子科技大学,2009。
[11]郝磊,OFDM系统信道估计技术研究[硕士学位论文],河北：燕山大学,2009。
[12]侯利明,林孝康,基于OFDM技术的多用户子载波分配算法[J],清华大学学报(自然科学版),2009(4),528-530。
[13]Tian Chongwen, LiYanting,YeWeilin,Quan Xiangyin,Song Zhanwei,Zheng Chuantao, Performance study of an OFDM visible light communication system based on white LED array[J]. Optoelectronics Letters,2011(6),454-457.
[14]李祥宇,OFDM协同通信系统中子载波分配算法的研究[硕士学位论文],北京：北京邮电大学,2010。
[15]Dingcheng Yang, Zhenghai Wang, Hao He,Jisheng Xu.Optimal Power Control for OFDM Signals over Two-Way Relay with Physical Network Coding[J]. Tsinghua Science and Technology.2011(12)569-575.
[16]苏威,潘志文,基于DFT的OFDM系统信道估计改进算法[J],无线通信技术,2007(4),1-5。
[17]Peter Jung, Paul Walter Baier. Advantages of CDMA and spread spectrum techniques over FDMA and TDMA in cellular mobile radio applications[J]. IEEE Transactions on Vehicular Technology,1993(8) 357-364.
[18]Zong Hua, Li Na. Study on Acknowledgement Assistant Inner Loop Power Control forCDMA2000 System[J]. Information and Communications Technologies.2011(6),102-107.
[19]WANG Ying, ZHANG Ping.A Service Differentiated MAC Protocol for OFDM/TDMA Wireless Systems[J]. The Journal of China Universities of Posts and Telecommunications.2005(2)13-19.
[20]曹红梅,张涛,基于IEEE 802.16a的OFDM-FDMA与OFDM-TDMA的性能比较[J],现代电子技术,2007(3),15～20。
[21]刘晓雪,郑宝玉,季薇,认知无线电网络中基于协作中继的资源分配算法,信号处理[J],2010(10),1441～1448。
[22]Wang Junfang, Zhu Guangxi, Jin Jiang, Bit allocation based on geneticalgorithm in multiuser OFDM systems[J]. Journal of Huazhong Universityof Science and Technology(Nature Science),2006(2).27-29.
[23]周广素,吴启晖,CR OFDM系统中具有QoS要求的自适应资源分配算法[J],解放军理工大学学报(自然科学版),2010(6),607-612。
[24]俎云霄,周杰,基于组合混沌遗传算法的认知无线电资源分配[J],物理学报.,2011(7),894-901。
[25]杨斌,广义扩展MIMO-OFDM系统中检测算法研究及优化[博士学位论文],北京：北京邮电大学,2007。
[26]王君,OFDM技术在海上无线通信系统的应用分析[J],无线通信技术,2011(2),36～39。
[27]吴忠丽,MIMO-OFDM系统中降低峰均比技术的研究[硕士学位论文],南京：东南大学,2009。
[28]Bo Gui, Leonard J. Cimini, Jr. Resource Allocation Algorithmsfor Multiuser Cooperative OFDM A Systems with Subchannel Permutation[C]. In:Information Sciences and Systems,2008. Princeton. USA 2008.3692-697.
[29]林懿诚,OFDM协同中继系统自适应资源分配技术研究[硕士学位论文],北京：北京邮电大学,2010。
[30]邵明秀,基于OFDM系统的用户编码协作通信[硕士学位论文],北京：北京邮电大学,2010。
[31]韩友才,协同通信实现方案研究[硕士学位论文],南京：南京邮电大学.2009。
[32]肖海勇,毕光国,张彭。采用子载波分组和空时码的随机映射MIMO-OFDM系统[J],电路与系统学报,2008(4),130-134。
[33]景秀,无线网络中协作分集技术研究[硕士学位论文],辽宁：大连理工大学,2008。
[34]芮贤义,金荣洪,耿军平,相关MIMO信道下空间分集系统中多用户分集性能[J],电波科学学报,2008(10),973～941。
[35]Bo Gui, Leonard J, Cimini, Jr.BIT LOADING ALGORITHMS FOR COOPER-ATIVE OFDM SYSTEMS[C]. Military Communications Conference,Orlando, Florida 2007.10,25-30
[36]刘威鑫,张忠培,李少谦等,协同分集下AF与DF比较[J],电子科技大学学报,2007(5),911～914.
[37]佘好求,虚拟MIMO中继系统协作编码技术研究[硕士学位论文],北京：北京邮电大学,2010。
[38]司江勃,李赞,刘增基,无线协作网络中存在干扰时的中继选择协议[J],西安交通大学学报,2010(2),72～76。
[39]Mischa Dohler, Athanasios Gkelias, Hamid Aghvami. A Resource Allocation Strategy for DistributedMIMO Multi-Hop Communication Systems[J]. IEEE Communications Letters.2004(2).
[40]Yidong Lang, Carsten Bockelmann,Dirk Wubben. A NOVEL RESOURCE ALLOCATION STRATEGY FOR DISTRIBUTED MIMO MULTIHOPMULTICOMMODITYCOMMUNICA-TIONS[C]. In:International ITG Workshop on Smart AntennasDarmstadt, Germany,26.-27. February 2008. 530-535.
[41]啜钢,裴静,刘洪来等,协同通信系统中一种新的分析吞吐量的方法[J],电子与信息学报,2010(6),1446～1451。
[42]王成金,李屹,张琳等,蜂窝小区内分层中继组播策略的信道容量分析[J],北京邮电大学学报,2010(6),54～57。
[2]庾志成,移动互联网的发展现状和发展趋势[J],移动通信,2008(9),22～24。
[3]甘雯昱,分布式无线通信环境中的循环延时分集技术[硕士学位论文],合肥：中国科学技术大学,2009。
[4]Yidong Lang,Dirk Wubben. Efficient Power Allocation for Outage Restricted Asymmetric Distributed MIMO Multi-hop Networks. In:Personal, Indoor and Mobile Radio Communications[C]. Cannes,2008.9:15-20.
[5]杜金玲,VAA小区划分方法研究[硕士学位论文],成都：电子科技大学,2009。
[6]LI Xiao, JIN Shi, GAO XiQi. Multi-user MIMO downlink eigen-mode transmission over jointly correlated MIMO channels[J]. Science ChinaInformation Sciences,2011(10),2124-2137.
[7]Rui Yin, Yu Zhang,Guanding Yu,Zhaoyang Zhang. Centralized and distributed resource allocation in OFDM based multi-relay system[J]. Journal of Zhejiang University-Science,2010(6)450-464.
[8]冯子豪,无线协同通信中的网络编码与中继选择[硕士学位论文],南京：南京邮电大学,2011。
[9]Edward C, van der Meulen. Transmission of Information in a T-terminalDiscre-te Memoryless Channel[M]. Los Angeles:University of California,1968.
[10]林威,无线通信中协同分集的性能分析与编码技术研究[硕士学位论文],成都：电子科技大学,2009。
[11]郝磊,OFDM系统信道估计技术研究[硕士学位论文],河北：燕山大学,2009。
[12]侯利明,林孝康,基于OFDM技术的多用户子载波分配算法[J],清华大学学报(自然科学版),2009(4),528-530。
[13]Tian Chongwen, LiYanting,YeWeilin,Quan Xiangyin,Song Zhanwei,Zheng Chuantao, Performance study of an OFDM visible light communication system based on white LED array[J]. Optoelectronics Letters,2011(6),454-457.
[14]李祥宇,OFDM协同通信系统中子载波分配算法的研究[硕士学位论文],北京：北京邮电大学,2010。
[15]Dingcheng Yang, Zhenghai Wang, Hao He,Jisheng Xu.Optimal Power Control for OFDM Signals over Two-Way Relay with Physical Network Coding[J]. Tsinghua Science and Technology.2011(12)569-575.
[16]苏威,潘志文,基于DFT的OFDM系统信道估计改进算法[J],无线通信技术,2007(4),1-5。
[17]Peter Jung, Paul Walter Baier. Advantages of CDMA and spread spectrum techniques over FDMA and TDMA in cellular mobile radio applications[J]. IEEE Transactions on Vehicular Technology,1993(8) 357-364.
[18]Zong Hua, Li Na. Study on Acknowledgement Assistant Inner Loop Power Control forCDMA2000 System[J]. Information and Communications Technologies.2011(6),102-107.
[19]WANG Ying, ZHANG Ping.A Service Differentiated MAC Protocol for OFDM/TDMA Wireless Systems[J]. The Journal of China Universities of Posts and Telecommunications.2005(2)13-19.
[20]曹红梅,张涛,基于IEEE 802.16a的OFDM-FDMA与OFDM-TDMA的性能比较[J],现代电子技术,2007(3),15～20。
[21]刘晓雪,郑宝玉,季薇,认知无线电网络中基于协作中继的资源分配算法,信号处理[J],2010(10),1441～1448。
[22]Wang Junfang, Zhu Guangxi, Jin Jiang, Bit allocation based on geneticalgorithm in multiuser OFDM systems[J]. Journal of Huazhong Universityof Science and Technology(Nature Science),2006(2).27-29.
[23]周广素,吴启晖,CR OFDM系统中具有QoS要求的自适应资源分配算法[J],解放军理工大学学报(自然科学版),2010(6),607-612。
[24]俎云霄,周杰,基于组合混沌遗传算法的认知无线电资源分配[J],物理学报.,2011(7),894-901。
[25]杨斌,广义扩展MIMO-OFDM系统中检测算法研究及优化[博士学位论文],北京：北京邮电大学,2007。
[26]王君,OFDM技术在海上无线通信系统的应用分析[J],无线通信技术,2011(2),36～39。
[27]吴忠丽,MIMO-OFDM系统中降低峰均比技术的研究[硕士学位论文],南京：东南大学,2009。
[28]Bo Gui, Leonard J. Cimini, Jr. Resource Allocation Algorithmsfor Multiuser Cooperative OFDM A Systems with Subchannel Permutation[C]. In:Information Sciences and Systems,2008. Princeton. USA 2008.3692-697.
[29]林懿诚,OFDM协同中继系统自适应资源分配技术研究[硕士学位论文],北京：北京邮电大学,2010。
[30]邵明秀,基于OFDM系统的用户编码协作通信[硕士学位论文],北京：北京邮电大学,2010。
[31]韩友才,协同通信实现方案研究[硕士学位论文],南京：南京邮电大学.2009。
[32]肖海勇,毕光国,张彭。采用子载波分组和空时码的随机映射MIMO-OFDM系统[J],电路与系统学报,2008(4),130-134。
[33]景秀,无线网络中协作分集技术研究[硕士学位论文],辽宁：大连理工大学,2008。
[34]芮贤义,金荣洪,耿军平,相关MIMO信道下空间分集系统中多用户分集性能[J],电波科学学报,2008(10),973～941。
[35]Bo Gui, Leonard J, Cimini, Jr.BIT LOADING ALGORITHMS FOR COOPER-ATIVE OFDM SYSTEMS[C]. Military Communications Conference,Orlando, Florida 2007.10,25-30
[36]刘威鑫,张忠培,李少谦等,协同分集下AF与DF比较[J],电子科技大学学报,2007(5),911～914.
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