毫微微型基地台之佈建與干擾分析

Deployment and Interference Analysis of Femtocell Base Stations

江宜芳(Yi-Fan Chiang)

指導教授 ： 林信標

國立臺北科技大學/電資學院/電腦與通訊研究所/碩士(2011年)

https://doi.org/10.6841/NTUT.2011.00540

摘要

毫微微型基地台(femtocell)是一種無線基地台，以小型化低功率的設計，將基地台的功能帶進一般家庭，只要接上家中非對稱式數位用戶迴路(Asymmetric Digital Subscriber Line，ADSL)或光纖等固網訊號，便能轉換為室內接收訊號，彌補室內無線訊號死角問題。當毫微微基地台佈建時，首要面臨的問題是該如何減少，對已存在的大型蜂巢式基地台(macrocell)網路之干擾。若有個好的佈建軟體或干擾分析機制，便可有效提昇毫微微基地台的使用效率。
本論文使用C++語言開發一個無線通訊系統的模擬軟體平台。此平台能夠隨機佈建或固定佈建基地台、使用者、建築物的位置，調整使用者、基地台、建築物的數量，並可依據遮蔽效應、路徑損耗、室內或室外環境，計算個別使用者的訊號-干擾雜訊比(SINR)和資料傳輸容量(capacity)。
對於降低毫微微基地台與大型蜂巢式基地台之間干擾的方法，本論文利用建構的模擬平台，動態調整毫微微型基地台之發射功率，最低-11.6dBm到最高20dBm，結果顯示不僅可消除對室外使用者的干擾，並在低的功率之下維持高的使用者資料傳輸容量(13Mbits/sec~75M Mbits/sec)。本論文另外提出馬可夫模型作為使用者端的排程預測，透過模擬平台的分析結果，可預估到使用者被加入排程的時間點，平均正確率約36.3%，毫微微型基地台便能依據預估的結果，轉換天線輻射場型，達到減輕干擾的效果。

關鍵字

毫微微型基地台 ； 干擾 ； 馬可夫模型 ； 排程

並列摘要

Femtocell is a wireless base station with small size, and low power. This user-installed device connects the cellular network and a broadband internet, such as asymmetric digital subscriber Line(ADSL) or fiber, in the home and increases the indoor coverage. For femtocell deployments, one important issue is how to mitigate the interference for existing macro cellular networks. If there is a good deployment software or a better analysis mechanism for interference mitigation, the femtocell usability can be increased.
We use C++ language to develop a communication simulation platform. This simulation platform can randomly or fixed deploy users, base stations, and buildings. The number of users, base stations, and buildings are all can be adjusted. Moreover, it can calculate the SINR and capacity of mobile users according to shadowing effects, path loss, indoor, and outdoor environment.
For mitigating the interference problems between femtocell and macrocell, we regulate transmit power of femtocell from -11.6dBm to 20dBm. The result shows that the interference can be decreased for outdoor user and maintained the high capacity of indoor user (13Mbits/sec~75M Mbits/sec). Besides, Markov model is used to predict the scheduling timing at user end. Through the analysis of the platform, we can correctly predict the scheduled timing of user and the average hit rate is about 36.3%. Thus femtocell base station can change the antenna pattern according to the Markov prediction and the purpose of mitigating the interference and be achieved.

並列關鍵字

Femtocell ； interference ； Markov model ； scheduling

參考文獻

[1] Holger Claussen, “Performance of Macro- and Co-Channel Femtocells in a Hierarchical Cell Structure,” IEEE Int’l Symp. Personal, Indoor and Mobile Radio Communications, pp. 1-5, Sept. 2007.

[2] Holger Claussen, “Co-Channel Operation of Macro- and Femtocells in a Hierarchical Cell Structure,” Internation Journal of Wireless Information Networks, Springer Netherlands, vol. 15, pp. 137-147,Sept. 2008.

[3] P. Lee, T. Lee, J. Jeong, and J. Shin, “Interference Management in LTE Femtocell Systems Using Fractional Frequency Reuse,” in Proc. IEEE ICACT’10, pp. 1047-1051, Feb. 2010.

[4] R. T. Juang, P. Ting, H. P. Lin, and D. B. Lin, “Interference Management of Femtocell in Macro-cellular Networks,” in Proc. IEEE WTS’10, p. 1-4, April, 2010.

[5] F. J. Mullany, L. T. W. Ho, L. G Samuel, and H. Claussen, “Self-deployment, self-configuration: Critical future paradigms for wireless access networks,” in Lecture Notes on Computer Science LNCS, vol. 3457, pp. 58–68. Springer, 2005.