OFDM系统的动态资源分配算法研究
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摘要
正交频分复用(OFDM)技术将无线信道划分为若干个相互正交的子信道,把高速的数据流通过串并转换,分配到传输速率相对较低的子信道中传输。它具有支持高速数据传输、抗多径干扰以及频谱效率高等优点,可以大幅提高频谱利用率。同时,OFDM系统能够根据各个子信道的衰落和多径时延特性,对系统资源(比特与功率等)进行动态分配,并且各个子载波可以进行自适应调制,具有很强的灵活性,既能进一步提高系统资源的利用效率,又可满足用户不同的容量需求。
OFDM系统的动态资源分配主要是根据实时的信道状态信息,对发送功率、子载波和每个子载波传送的比特数进行自适应调配。本文首先根据OFDM系统自适应技术的原理介绍了注水定理,接着对主要的功率分配、比特分配算法进行了分析和比较,着重分析各个算法的原理及性能;然后提出了次优化算法,并对这些算法进行了仿真分析,结果表明,次优算法在大大降低算法的复杂度的同时保持了较好的性能;最后本文通过比较这些算法的优缺点,讨论了对算法的扩展应用和优化。
Orthogonal Frequency Division Multiplexing(OFDM)is a promising technique with high spectral efficiency. It divides wireless channel into N orthogonal subchannels, then converts high speed serial bits stream to parallel and transmit through lower speed subchannels. So it can support high speed data service, and hasstrong capacity of combating with multipath interference. Simultaneously, OFDM can dynamically allocate system resources (such as bit, power, etc.) according to subchannel's fading and multipath delay characteristics, and every subcarrier can carry on self-adaptation modulation. Thus, it has much strong flexibility, and can not only improve the utilization efficiency of system resources, but also meet user's different capacity demands.
The dynamic resource allocation for OFDM systems mainly includes adaptive power allocation, adaptive sub-channel allocation and adaptive bit loading. At first,the paper introduced the theory of OFDM systems, and made analysis and comparison for the algorithms of power allocation, bit allocation and self-adaptation modulation. Then we make sub-optimal algorithms ourselves and compare their complexities and performance with the optimal algorithm by the simulation. We can find that these algorithms have lower complexity than the optimal algorithm with the close performance at the same time. At last through comparing the advantages and disadvantages of these algorithms ,we have discuss the expansion of the algorthm , s application.
OFDM系统的动态资源分配主要是根据实时的信道状态信息,对发送功率、子载波和每个子载波传送的比特数进行自适应调配。本文首先根据OFDM系统自适应技术的原理介绍了注水定理,接着对主要的功率分配、比特分配算法进行了分析和比较,着重分析各个算法的原理及性能;然后提出了次优化算法,并对这些算法进行了仿真分析,结果表明,次优算法在大大降低算法的复杂度的同时保持了较好的性能;最后本文通过比较这些算法的优缺点,讨论了对算法的扩展应用和优化。
Orthogonal Frequency Division Multiplexing(OFDM)is a promising technique with high spectral efficiency. It divides wireless channel into N orthogonal subchannels, then converts high speed serial bits stream to parallel and transmit through lower speed subchannels. So it can support high speed data service, and hasstrong capacity of combating with multipath interference. Simultaneously, OFDM can dynamically allocate system resources (such as bit, power, etc.) according to subchannel's fading and multipath delay characteristics, and every subcarrier can carry on self-adaptation modulation. Thus, it has much strong flexibility, and can not only improve the utilization efficiency of system resources, but also meet user's different capacity demands.
The dynamic resource allocation for OFDM systems mainly includes adaptive power allocation, adaptive sub-channel allocation and adaptive bit loading. At first,the paper introduced the theory of OFDM systems, and made analysis and comparison for the algorithms of power allocation, bit allocation and self-adaptation modulation. Then we make sub-optimal algorithms ourselves and compare their complexities and performance with the optimal algorithm by the simulation. We can find that these algorithms have lower complexity than the optimal algorithm with the close performance at the same time. At last through comparing the advantages and disadvantages of these algorithms ,we have discuss the expansion of the algorthm , s application.
引文
[1]ZuKang Shen,Jeffrey G.Andrews and Brian L.Evans, “Optimal Power Allocation in Multi-user OFDM Systems,”in Proceedings of the IEEE Global Communication.Conference,San Francisco,Vo1.1,pp.337-341,Dec.2003.
[2]Czylwik A., “Adaptive OFDM for Wideband Radio Channel,in Proc.IEEE GLOBECOM,1996,pp.713-718.
[3] 钱学荣,张力军,移动衰落信道中的自适应 OFDM 调制,南京邮电学院院报,2003 年 3 月.
[4] Gordon L.Stuber 著,裴昌幸等译.移动通信原理(第二版).北京:电子工业出版社,2004, 101.
[5] TeroOjanpera,Ramjee Prasad 著,朱旭红译.宽带 CDMA:第三代移动通信技术北京:人民邮电出版社,2001, 7.
[6] R. W. Chang,“Synthesis of band-limited orthogonal signals for multichannel data transmission,” Bell System Tech. J. Vol. 45, pp.1775-1796, Dec. 1966.
[7] John G.Proakis, “Digital Communications”影印第四版,McGraw Hill,October,2001.
[8] 吴伟陵.移动通信中的关键技术.北京:北京邮电大学出版社,2000,241-244.
[9] 佟学俭,罗涛.OFDM移动通信技术原理与应用.北京:人民邮电出版社,2003,6.
[10] 王文博,郑侃.宽带无线通信OFDM技术.北京:人民邮电出版社,2003,11.
[11]W. P. Robins, “Phase noise in Signal Sources,” IEEE Telecommunication. series 9, 1991.
[12] 郭梯云,杨家玮等.数字移动通信.北京:人民邮电出版社,1996,3.
[13] 王京,姚彦.数字移动通信信道的计算机模拟.电信科学,1991.4.
[14] 樊昌信等.通信原理(第四版).国防工业出版社,1999.
[15] 张贤达.现代信号处理.清华大学出版社,1995.
[16] 方波,赵力,孙献璞.新兴的OFDM技术.通讯世界,2001.5.
[17]Richard Van Nee, RamjeePrasad,"OFDMWirelessMultimediaCommunications", ArtechHouse,Boston,London,2000.
[18]Rainer Grunheid,Edgar Bolinth,Hermann Rohling,Kurt Aretz," Adaptive Modulation for the HIPERLAN/2 Air Interface",5th International OFDM-Workshop2000 ,Hamburg.
[19]Tom Bruns, "Performance Comparison of Multiuser OFDM Techniques", Ph.D Thesis,Stanford University.
[20]Slawomir Pietrzyk, Gerard Janssen, "Collision-based Uplink OFDMA System Exploiting frequency Selectivity of a Multipath Channel",ATAMS'01,June 2001,Cracow ,Poland.
[21]Wonjong Rhee,John M .Cioffi, “Increase in Capacity of Multiuser OFDM system Using Dynamic Subchannel Allocation",ProceedingsVTC,vol.2,pp .41 085-1089,Ma y 2000.
[22]Hideki Ochiai, and Hideki Imai, "MDPSK-OFDM with Highly Power-Efficient Block Codes for Frequency-Selective Fading Channels",IEEE Trans.Vehi.Tech.,Vol.49,N o.1, pp 74-82,Jan.2000.
[23]Naofal Al-Dhahir,and John M .Ciofi,"Optimum Finite-Length Equalization for Multi –carrier Transceivers",IEEE Trans.Comm.,Vol.44,No.l,p p.56-64,J an 1996.
[24]Karthik Shanmu,' Study of Adaptive Bit Loading for OFDM systems', EE359 Wireless Communications,Fall 2002.
[25]Ahamd R. S. Bahai, B. R. Sailtzberg, Multi-Carrier Digital Communication Theory and Applications of OFDM,Kluwer Academic/Plenum,1999.
[26]J A C Bingham. Multicarrier modulation for data transmission :Anidea whose Time has come[J ].IEEEC omm Mag, 1990,2 8(5):5 ~14.
[27]高欢芹.OFDM系统自适应调制与功率分配的研究及其在IEEE802.16e协议中的应用.南京.南京邮电大学.2002.
[28]L.J Cimini,Jr,et al.Advanced Celluar Internet Service(ACIS),IEEE Commun.Mag,Oct.1998:36(10):150 ~159.
[29]D.Shiu,G.J.Foschini,M.J.Gans,and J.M.Kahn, “Fading correlation and its effect on the capacity of multielement antenna systems,”IEEE Trans.Commun,pp.502~513,Mar.2000.
[30]Z.Song,K.Zhang,and Y.Guan, “Statistical adaptive modulation for QAM-OFDM systems,”in Proc.Globecom.Conf.,Taipei,Taiwan,Nov.2002,vol.1,pp.706~710.
[31]赵丽丹.基于IEEE802.26a的多用户OFDM系统自适应子信道和比特、功率分配.南京.南京邮电学院.2003.
[32]R.Negi and J.M.Cioffi, “ Delay-constrained capacity with causal feedback,”IEEE Trans.Inform.Therory,vol.48,no.9,pp.2478~2494,Sept.2002.
[33]J.Jang and K.B.Lee, “Transmit Power Adaptation for Multiuser OFDM Systems,”IEEE Journal on Selected Areas inCommunications,vol.21,no.2,pp.171~178,Feb.2003.
[34]张卓奎,陈慧婵.随机过程.西安:西安电子科技大学出版社,2003.
[35]I.Kim,H.L.LEE,B.Kim,and Y.H.Lee, “On the Use of Linear Programming for Dynamic Subchannel and Bit Allocation in Multiuser OFDM,”in Proc.IEEE Global Communications Conference,vol.6,pp.3648~3652,Nov.2001.
[36]蔡叶飞.OFDM系统资源分配算法研究.北京.北京邮电大学.2004.
[2]Czylwik A., “Adaptive OFDM for Wideband Radio Channel,in Proc.IEEE GLOBECOM,1996,pp.713-718.
[3] 钱学荣,张力军,移动衰落信道中的自适应 OFDM 调制,南京邮电学院院报,2003 年 3 月.
[4] Gordon L.Stuber 著,裴昌幸等译.移动通信原理(第二版).北京:电子工业出版社,2004, 101.
[5] TeroOjanpera,Ramjee Prasad 著,朱旭红译.宽带 CDMA:第三代移动通信技术北京:人民邮电出版社,2001, 7.
[6] R. W. Chang,“Synthesis of band-limited orthogonal signals for multichannel data transmission,” Bell System Tech. J. Vol. 45, pp.1775-1796, Dec. 1966.
[7] John G.Proakis, “Digital Communications”影印第四版,McGraw Hill,October,2001.
[8] 吴伟陵.移动通信中的关键技术.北京:北京邮电大学出版社,2000,241-244.
[9] 佟学俭,罗涛.OFDM移动通信技术原理与应用.北京:人民邮电出版社,2003,6.
[10] 王文博,郑侃.宽带无线通信OFDM技术.北京:人民邮电出版社,2003,11.
[11]W. P. Robins, “Phase noise in Signal Sources,” IEEE Telecommunication. series 9, 1991.
[12] 郭梯云,杨家玮等.数字移动通信.北京:人民邮电出版社,1996,3.
[13] 王京,姚彦.数字移动通信信道的计算机模拟.电信科学,1991.4.
[14] 樊昌信等.通信原理(第四版).国防工业出版社,1999.
[15] 张贤达.现代信号处理.清华大学出版社,1995.
[16] 方波,赵力,孙献璞.新兴的OFDM技术.通讯世界,2001.5.
[17]Richard Van Nee, RamjeePrasad,"OFDMWirelessMultimediaCommunications", ArtechHouse,Boston,London,2000.
[18]Rainer Grunheid,Edgar Bolinth,Hermann Rohling,Kurt Aretz," Adaptive Modulation for the HIPERLAN/2 Air Interface",5th International OFDM-Workshop2000 ,Hamburg.
[19]Tom Bruns, "Performance Comparison of Multiuser OFDM Techniques", Ph.D Thesis,Stanford University.
[20]Slawomir Pietrzyk, Gerard Janssen, "Collision-based Uplink OFDMA System Exploiting frequency Selectivity of a Multipath Channel",ATAMS'01,June 2001,Cracow ,Poland.
[21]Wonjong Rhee,John M .Cioffi, “Increase in Capacity of Multiuser OFDM system Using Dynamic Subchannel Allocation",ProceedingsVTC,vol.2,pp .41 085-1089,Ma y 2000.
[22]Hideki Ochiai, and Hideki Imai, "MDPSK-OFDM with Highly Power-Efficient Block Codes for Frequency-Selective Fading Channels",IEEE Trans.Vehi.Tech.,Vol.49,N o.1, pp 74-82,Jan.2000.
[23]Naofal Al-Dhahir,and John M .Ciofi,"Optimum Finite-Length Equalization for Multi –carrier Transceivers",IEEE Trans.Comm.,Vol.44,No.l,p p.56-64,J an 1996.
[24]Karthik Shanmu,' Study of Adaptive Bit Loading for OFDM systems', EE359 Wireless Communications,Fall 2002.
[25]Ahamd R. S. Bahai, B. R. Sailtzberg, Multi-Carrier Digital Communication Theory and Applications of OFDM,Kluwer Academic/Plenum,1999.
[26]J A C Bingham. Multicarrier modulation for data transmission :Anidea whose Time has come[J ].IEEEC omm Mag, 1990,2 8(5):5 ~14.
[27]高欢芹.OFDM系统自适应调制与功率分配的研究及其在IEEE802.16e协议中的应用.南京.南京邮电大学.2002.
[28]L.J Cimini,Jr,et al.Advanced Celluar Internet Service(ACIS),IEEE Commun.Mag,Oct.1998:36(10):150 ~159.
[29]D.Shiu,G.J.Foschini,M.J.Gans,and J.M.Kahn, “Fading correlation and its effect on the capacity of multielement antenna systems,”IEEE Trans.Commun,pp.502~513,Mar.2000.
[30]Z.Song,K.Zhang,and Y.Guan, “Statistical adaptive modulation for QAM-OFDM systems,”in Proc.Globecom.Conf.,Taipei,Taiwan,Nov.2002,vol.1,pp.706~710.
[31]赵丽丹.基于IEEE802.26a的多用户OFDM系统自适应子信道和比特、功率分配.南京.南京邮电学院.2003.
[32]R.Negi and J.M.Cioffi, “ Delay-constrained capacity with causal feedback,”IEEE Trans.Inform.Therory,vol.48,no.9,pp.2478~2494,Sept.2002.
[33]J.Jang and K.B.Lee, “Transmit Power Adaptation for Multiuser OFDM Systems,”IEEE Journal on Selected Areas inCommunications,vol.21,no.2,pp.171~178,Feb.2003.
[34]张卓奎,陈慧婵.随机过程.西安:西安电子科技大学出版社,2003.
[35]I.Kim,H.L.LEE,B.Kim,and Y.H.Lee, “On the Use of Linear Programming for Dynamic Subchannel and Bit Allocation in Multiuser OFDM,”in Proc.IEEE Global Communications Conference,vol.6,pp.3648~3652,Nov.2001.
[36]蔡叶飞.OFDM系统资源分配算法研究.北京.北京邮电大学.2004.