隨著行動裝置的普及化，越來越多人能夠享有隨時隨地的網路服務，因此，無線資料傳輸量的爆炸性成長也是無可避免的。然而，單靠傳統大型基地台(Macro)來提供使用者服務已顯得無法負荷，再加上大型基地台建置成本高且消耗功率大，而沒有辦法太過密集的佈署。於是，在大型基地台涵蓋範圍下加入小型基地台來補強超過負荷的傳輸量則變成一種解決方法，也就促使了異質網路的誕生。本論文建立此網路架構來探討收益成本比，希望藉由此研究找出對電信業者以及使用者都能滿意的成果，也就是在電信業者賺錢的同時，也能提供使用者良好的服務品質。本論文透過數學模型來建立此系統架構，不過由於原數學模型屬於混合整數非線性分數規劃問題(MINLFP)，求解難度過高，我們使用數學技巧來簡化此模型，讓它變為一混合整數線性規劃問題(MILP)，最後則使用C++程式及最佳化求解軟體CPLEX來進行模擬，得到我們的最佳解。

Along with the popularity of electronic products, many and many people are able to access the internet for obtaining information in any time and at anywhere. Consequently, the explosive growth of wireless data transmission is inevitable. However, the traditional base station is insufficient to provide service for satisfying all users nowadays. Therefore, the incorporation of small cell into original base station’s coverage promotes the advent of heterogeneous networks. In this research, we construct a communication system described by a mathematic system to stimulate our optimized result, which is the ratio of revenue and expenditure. We propose a MINLFP model to depict our system structure, and we simplify this MINLFP model to a less complicated MILP model by a series of mathematical techniques. First, Piecewise-RLT and an approximation method of log term are used for the purpose of linear relaxation. Secondly, we emerge the CCT transform to convert linear fractional programing to linear programing. The final step is to adopt C++ programming and via the cooperation of CPLEX solving package to generate our optimal solution. By observing our numerical results, we find it more profitable if the number of users increases. In which would be the cause of base station’s fundamental construction cost. Nonetheless, it is likely to degrade the QoS of users if there are too many to contend for the resources. As a result, how to maintain a balance in between is a critical and imperative issue.

[1] V.N. Ha and L.B. Le, “Distributed base station association and power control for heterogeneous cellular networks,” IEEE Trans. Veh. Technology, vol. 63, no. 1, pp. 282–296, Jan. 2014.
[2] Hakim Ghazzai, Muhammad Junaid Farooq, Ahmad Alsharoa, Elias Yaacoub, Abdullah Kadri and Mohamed-Slim Alouini, “Green Networking in Cellular HetNets: A Unified Radio Resource Management Framework with Base Station ON/OFF Switching,” IEEE Transactions on Vehicular Technology, December 2016.
[3] Stepan Kucera, Lester Ho, Rouzbeh Razavi, Holger Claussen, “Coverage Optimization Trade-Offs in Heterogeneous W-CDMA Networks with Co-Channel Small Cells,” in Vehicular Technology Conference, IEEE, Seoul, South Korea, May 2014.
[4] 3GPP TS 36 211, Release 12, “LTE; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation,” July 2015.
[5] ITU-R M.2135-1, “Guidelines for evaluation of radio interface technologies for IMT-Advanced,” December 2009.
[6] Chrysanthos E. Gounaris, Ruth Misener and Christodoulos A. Floudas, Computational Comparison of Piecewise-Linear Relaxations for Pooling Problems. Ind. Eng. Chem. Res. 48, 5742–5766, May 2009.
[7] Y. Shi, Y. T. Hou, S. Kmpella, H. D. Sherali, “Maximizing Capacity in Multihop Cognitive Radio Networks under the SINR Model,” IEEE Transactions on Mobile Computing, 2011, pp. 954-967.
[8] Misener, R., Thompson, J.P., Floudas, C.A., “APOGEE: Global optimization of standard, generalized: and extended pooling problems via linear and logarithmic partitioning schemes,” Comput. Chem. Eng. 35, 876–892., May 2011.
[9] Dajun Yue, Gonzalo Guillén-Gosálbez, Fengqi You, “Global optimization of large-scale mixed-integer linear fractional programming problems: A reformulation-linearization method and process scheduling applications,” AIChE Journal, Vol. 59, No. 11, pp. 4255–4272, November 2013.
[10] John E. Mitchell, “Branch-and-Cut Algorithms for Combinatorial Optimization Problems,” Oxford University Press, 2000.
[11] W. Guo and T. O’Farrell, “Capacity-Energy-Cost Tradeoff for SmallCell Networks,” in Vehicular Technology Conference, IEEE, Yokohama, Japan, May 2012.
[12] L. Chen, X. Li, and H. Ji, “An Interference-Mitigation Channel Allocation Algorithm for Energy-Efficient Femtocell Networks,” IEEE WCNC, 2014, pp. 2318-2323.
[13] Walid, A., Kobbane, A., Sabir, E., Ben-Othman, J., & El Koutbi, M., Exploiting Multi-homing in Hyper Dense LTE Small-Cells Deployments. To appear in proceedings of the Wireless Communications and Networking Conference (WCNC 2016). Doha, Qatar
[14] G. Auer, V. Giannini, C. Desset, I. Godor, P. Skillermark, M. Olsson, M. Imran, D. Sabella, M. Gonzalez, O. Blume, and A. Fehske, “How much energy is needed to run a wireless network?” IEEE Wireless Communication, vol. 18, no. 5, pp. 40–49, Oct. 2011.