移动信道建模中的关键算法设计与实现
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摘要
随着移动互联网的飞速发展,有越来越多的业务都以手机端的形式展现在人们的面前。业务的推广和发展给无线网络的规划带来了巨大的挑战,传统的2G网络已经成为了移动互联网发展的瓶颈,而大规模3G网络的部署以及LTE的试用的推广和以LTE-A为代表性的4G技术的研发,都为移动互联网的发展提供了更好的网络基础。在无线网络的规划和部署过程中,由于传播预测不够准确为网络的升级改造带来巨大的困难。因此一直重点研究可以准确预测传播特性的确定性无线信道建模。针对射线跟踪信道建模时间复杂度高、运行效率低的问题,基于企业需求本文做了深入的研究,致力于改进射线跟踪的运行效率。
首先研究了无线信道的特点及其影响因素,并针对当前较为成熟的信道模型进行了深入的学习,掌握了其特点,并熟悉了当前常用的无线信道预测方法。之后针对射线跟踪信道建模方法进行了深入的研究,主要研究了其关键算法和当前常用的射线跟踪方法和比较成熟的加速算法,比较不同算法之间的优劣。本文通过C#调用AutoCAD的接口从而获得场景的三维几何信息,并针对直接获取的几何信息不足的现状提出了基于现有信息补全不足信息的算法。针对当前四面体结构的场景存储格式可以有效提升信道仿真的速率,但是缺少适用于通信场景的四面体划分方法,本文基于散乱点集的四面体化算法提出了Delaunay改进四面体剖分算法,通过C#编程实现该算法。在完成剖分之后综合多种方法验证了算法运行后剖分结果的正确性,同时对算法实现过程中遇到的问题进行了整理并给出了有效地解决方案。基于四面体结构存储格式的场景提出相应的射线跟踪算法并用C#实现了该算法,保证能够对该种格式的场景进行传播预测。最后在本文当前研究成果的基础上,对下一步的研究方向做了梳理。
With the rapid development of mobile Internet, more and more services are displayed with the form of a mobile terminal for us. The development and promotion of the mobile services have brought huge challenges to the wireless network planning. The traditional2G networks have become a bottleneck in the development of the mobile network. To provide the mobile Internet with better network infrastructure,3G networks are deployed massively as well as the commercial trial of LTE and the research and development of LTE-A which is the typical4G network. When we plan and deploy the network or upgrade the current networks, we meet a lot of challenges because of the bad propagation prediction. Therefore we have been focused on the research of deterministic channel modeling which can predict the propagation accurately. Against the problems of ray-tracing, such as high complexity and low operating efficiency, this paper study the problem deeply aiming to improve the efficiency of ray tracing on the demand of company.
First, we study the characteristics of the mobile channel and its influencing factors. We got the current channel prediction method and mastered the characteristics of the mature channel modeling. Then we study the ray-tracing channel modeling, research the key algorithm and the acceleration methods, and compare the advantages and disadvantages of every method. This paper calls the AutoCAD interface to obtain the three-dimensional geometric information of the scenario, and complement the missing information which cannot be obtained from the AutoCAD file directly. Now the tetrahedron scenario format can enhance the rate of the channel simulation, but there is no proper division method for the scenario for communication. This paper proposed a tetrahedron division method based on Delaunay and implemented the algorithm with C# language. After the completion of the division, we verify the correctness of the result with variety of methods and describe the problems we met while implementing the algorithm and give the effective solutions to each problem. We propose the ray-tracing algorithm for the tetrahedron scenario format and implemented it with C#language, and verify that this scenario format can be used for propagation prediction effectively. Finally, this paper list the future research directions based on the current research achievements.
首先研究了无线信道的特点及其影响因素,并针对当前较为成熟的信道模型进行了深入的学习,掌握了其特点,并熟悉了当前常用的无线信道预测方法。之后针对射线跟踪信道建模方法进行了深入的研究,主要研究了其关键算法和当前常用的射线跟踪方法和比较成熟的加速算法,比较不同算法之间的优劣。本文通过C#调用AutoCAD的接口从而获得场景的三维几何信息,并针对直接获取的几何信息不足的现状提出了基于现有信息补全不足信息的算法。针对当前四面体结构的场景存储格式可以有效提升信道仿真的速率,但是缺少适用于通信场景的四面体划分方法,本文基于散乱点集的四面体化算法提出了Delaunay改进四面体剖分算法,通过C#编程实现该算法。在完成剖分之后综合多种方法验证了算法运行后剖分结果的正确性,同时对算法实现过程中遇到的问题进行了整理并给出了有效地解决方案。基于四面体结构存储格式的场景提出相应的射线跟踪算法并用C#实现了该算法,保证能够对该种格式的场景进行传播预测。最后在本文当前研究成果的基础上,对下一步的研究方向做了梳理。
With the rapid development of mobile Internet, more and more services are displayed with the form of a mobile terminal for us. The development and promotion of the mobile services have brought huge challenges to the wireless network planning. The traditional2G networks have become a bottleneck in the development of the mobile network. To provide the mobile Internet with better network infrastructure,3G networks are deployed massively as well as the commercial trial of LTE and the research and development of LTE-A which is the typical4G network. When we plan and deploy the network or upgrade the current networks, we meet a lot of challenges because of the bad propagation prediction. Therefore we have been focused on the research of deterministic channel modeling which can predict the propagation accurately. Against the problems of ray-tracing, such as high complexity and low operating efficiency, this paper study the problem deeply aiming to improve the efficiency of ray tracing on the demand of company.
First, we study the characteristics of the mobile channel and its influencing factors. We got the current channel prediction method and mastered the characteristics of the mature channel modeling. Then we study the ray-tracing channel modeling, research the key algorithm and the acceleration methods, and compare the advantages and disadvantages of every method. This paper calls the AutoCAD interface to obtain the three-dimensional geometric information of the scenario, and complement the missing information which cannot be obtained from the AutoCAD file directly. Now the tetrahedron scenario format can enhance the rate of the channel simulation, but there is no proper division method for the scenario for communication. This paper proposed a tetrahedron division method based on Delaunay and implemented the algorithm with C# language. After the completion of the division, we verify the correctness of the result with variety of methods and describe the problems we met while implementing the algorithm and give the effective solutions to each problem. We propose the ray-tracing algorithm for the tetrahedron scenario format and implemented it with C#language, and verify that this scenario format can be used for propagation prediction effectively. Finally, this paper list the future research directions based on the current research achievements.
引文
[1]周正,王鲜芳等译,Jochen Schiller著,移动通信,北京,高等教育出版社,2005.12：1-15
[2]杨大成等.移动传播环境：理论基础、分析方法和建模技术.北京：机械工业出版社.2003.8：38-154
[3]啜钢,王文博,常永宇等.移动通信原理与系统(第2版).北京：北京邮电大学出版社,2009.2：8-32
[4]Bullingto,K., "Radio Propagation at Frequencies above 30 Megacycles", Proceedings of the IEEE,35, pp.1122-1136,1947
[5]Ament, W.S. "Toward a Theory of Reflection by a Rough Surface", Proceedings of the IRE,Vol.41,No.1,pp.142-146, Jan 1953
[6]Theodore S. Rappaport著.无线通信原理与应用(英文版)第二版.北京：电子工业出版社.2004.3：72-176
[7]吴伟陵,牛凯编著,移动通信原理(第二版),北京：电子工业出版社,2009.10：1-32
[8]陈德荣,刘永乾,蒋丽著,移动通信网络规划与工程设计,北京：北京邮电大学出版社,2010.3：33-51
[9]Stege, M.; Jelitto, J.; Bronzel, M.; Fettweis, G.;, "A multiple input-multiple output channel model for simulation of Tx-and Rx-diversity wireless systems," Vehicular Technology Conference,2000. IEEE VTS-Fall VTC.52nd, vol.2, no., pp.833-839,2000.
[10]Almers P. Bonek E. and Burr A. etc. Survey of Channel and Radio Propagation Models for Wireless MIMO Systems. EURASIP Journal on Wireless Communications and Networking. vol.2,2007.
[11]Loredo, S.; Rodriguez-Alonso, A.; Torres, R.P.; "Indoor MIMO Channel Modeling by Rigorous GO/UTD-Based Ray Tracing," Vehicular Technology. IEEE Transactions on, vol.57, no.2, pp.680-692, March 2008.
[12]Nam-Ryul Jeon, Chang-Hoon Lee, Noh-Gyoung Kang, etc. "Performance of Channel Prediction Using 3D Ray-tracing Scheme Compared to Conventional 2D Scheme," Communications. APCC '06. Asia-Pacific Conference on, vol., no., pp.1-6, Aug.2006.
[13]IST-WINNER Ⅱ Deliverable 1.1.2 v.1.2, "WINNER Ⅱ Channel Models", IST-WINNER2, Tech. Rep.,2007 (http://www.ist-winner.org/deliverables.html).
[14]吴志忠,移动通信无线电波传播,北京：人民邮电出版社,2002.9：219-262
[15]江茂光,几何绕射理论(第二版),西安：西安电子科技大学出版社.1994
[16]Zhou Ji, Bin-Hong Li, Hao-Xing Wang, Hsing-Yi Chen, Sarkar T.K., "Efficient ray-tracing methods for propagation prediction for indoor wireless communications," Antennas and Propagation Magazine, IEEE, Vol.43, pp.41-49, April 2001.
[17]周培德著,计算几何-算法设计与分析(第4版),北京：清华大学出版社.2011.9：117-223
[18]Yerry M A, Shephard M S. "Automatic three-dimensional mesh generation by the modified octree technique". International Journal for Numerical Methods in Engineering, 1984
[19]邓俊辉译,Mark de Berg, Otfried Cheong等著,计算几何算法与应用(第3版)北京：清华大学出版社.2009.8：151-224
[20]ITU-R M.2135:"Guidelines for evaluation of radio interface technologies for IMT-Advanced," 2008.
[21]F.A Alves, M.R.M.L. Albuquerque, S.G.Silva and A.G.d' Assuncao, "USING EFFICIENT RAY-TRACING TECHNIQUES TO PREDICT PROPAGATION LOSSES IN INDOOR ENVIRONMENTS," MIROWAVE AND OPTICAL TECHNOLOGY LETTERS, Vol.49, pp.854-858, April 2007.
[2]杨大成等.移动传播环境：理论基础、分析方法和建模技术.北京：机械工业出版社.2003.8：38-154
[3]啜钢,王文博,常永宇等.移动通信原理与系统(第2版).北京：北京邮电大学出版社,2009.2：8-32
[4]Bullingto,K., "Radio Propagation at Frequencies above 30 Megacycles", Proceedings of the IEEE,35, pp.1122-1136,1947
[5]Ament, W.S. "Toward a Theory of Reflection by a Rough Surface", Proceedings of the IRE,Vol.41,No.1,pp.142-146, Jan 1953
[6]Theodore S. Rappaport著.无线通信原理与应用(英文版)第二版.北京：电子工业出版社.2004.3：72-176
[7]吴伟陵,牛凯编著,移动通信原理(第二版),北京：电子工业出版社,2009.10：1-32
[8]陈德荣,刘永乾,蒋丽著,移动通信网络规划与工程设计,北京：北京邮电大学出版社,2010.3：33-51
[9]Stege, M.; Jelitto, J.; Bronzel, M.; Fettweis, G.;, "A multiple input-multiple output channel model for simulation of Tx-and Rx-diversity wireless systems," Vehicular Technology Conference,2000. IEEE VTS-Fall VTC.52nd, vol.2, no., pp.833-839,2000.
[10]Almers P. Bonek E. and Burr A. etc. Survey of Channel and Radio Propagation Models for Wireless MIMO Systems. EURASIP Journal on Wireless Communications and Networking. vol.2,2007.
[11]Loredo, S.; Rodriguez-Alonso, A.; Torres, R.P.; "Indoor MIMO Channel Modeling by Rigorous GO/UTD-Based Ray Tracing," Vehicular Technology. IEEE Transactions on, vol.57, no.2, pp.680-692, March 2008.
[12]Nam-Ryul Jeon, Chang-Hoon Lee, Noh-Gyoung Kang, etc. "Performance of Channel Prediction Using 3D Ray-tracing Scheme Compared to Conventional 2D Scheme," Communications. APCC '06. Asia-Pacific Conference on, vol., no., pp.1-6, Aug.2006.
[13]IST-WINNER Ⅱ Deliverable 1.1.2 v.1.2, "WINNER Ⅱ Channel Models", IST-WINNER2, Tech. Rep.,2007 (http://www.ist-winner.org/deliverables.html).
[14]吴志忠,移动通信无线电波传播,北京：人民邮电出版社,2002.9：219-262
[15]江茂光,几何绕射理论(第二版),西安：西安电子科技大学出版社.1994
[16]Zhou Ji, Bin-Hong Li, Hao-Xing Wang, Hsing-Yi Chen, Sarkar T.K., "Efficient ray-tracing methods for propagation prediction for indoor wireless communications," Antennas and Propagation Magazine, IEEE, Vol.43, pp.41-49, April 2001.
[17]周培德著,计算几何-算法设计与分析(第4版),北京：清华大学出版社.2011.9：117-223
[18]Yerry M A, Shephard M S. "Automatic three-dimensional mesh generation by the modified octree technique". International Journal for Numerical Methods in Engineering, 1984
[19]邓俊辉译,Mark de Berg, Otfried Cheong等著,计算几何算法与应用(第3版)北京：清华大学出版社.2009.8：151-224
[20]ITU-R M.2135:"Guidelines for evaluation of radio interface technologies for IMT-Advanced," 2008.
[21]F.A Alves, M.R.M.L. Albuquerque, S.G.Silva and A.G.d' Assuncao, "USING EFFICIENT RAY-TRACING TECHNIQUES TO PREDICT PROPAGATION LOSSES IN INDOOR ENVIRONMENTS," MIROWAVE AND OPTICAL TECHNOLOGY LETTERS, Vol.49, pp.854-858, April 2007.