小細胞網路下同調多點傳輸機制之預編碼技術

Precoding for CoMP transmission in Small cell Networks

沈恬雅(Tanya Singh)

指導教授 ： 伍紹勳

國立交通大學/電機學院/電機資訊國際學位學程/碩士(2019年)

摘要

協調多點傳輸方案為管理和減輕干擾以提高網絡性能和可靠性之一種有效且具有發展性的技術。在本論文中，我們利用資源分配演算法在小細胞網路下找出新的下行協調多點協調式波束成形預編碼矩陣。比例式公平排班演算法利用多輸入多輸出預編碼技術和比例式公平資源分配演算法來解決小細胞平均使用者頻譜效率與小細胞邊界使用者頻譜效率之間的取捨問題。資源分配問題因鄰近使用者的干擾而為非凸函數，為了解決此問題，我們利用一個基於平行連續凸函數近似的演算法找出多輸入多輸出同調多點傳輸網路下的的最佳操作點(預編碼與功率分配)。該演算法解出一系列強凸子問題並使接入點能夠並行地更新其優化變量。我們推導出最優預編碼矩陣和最優功率分配的閉合表達式。並透過模擬比較本論文之預編碼方法與迫零預編碼的表現。

關鍵字

超密網絡 ； 小細胞網路 ； 同調多點傳輸 ； 比例公平的資源分配

並列摘要

Coordination multi-point (CoMP) transmission scheme is introduced as an effective and promising technology that manages and mitigates interference to improve network performance and reliability. In this thesis, we use resource allocation to obtain new precoding matrices for a downlink CoMP coordinated beamforming (CB) in a small cell network. The trade-off between cell-average and cell-edge user spectral-efficiency is addressed by the application of proportional- fair scheduling using MIMO transmit precoding and proportional- fair resource allocation. A parallel successive convex approximation (SCA) – based algorithm is introduced, as the resource allocation problem becomes non- convex due to the interferences from the neighboring users, to solve for the optimal operating point (precoding and power allocation) in a MIMO CoMP network setup. A sequence of strongly convex sub-problems is now solved using the algorithm, enabling the access points (AP) to update their optimization variables in parallel. The optimal precoding matrices and the closed-form expression for an optimal power allocation are derived. The performance of the new precoder is studied by comparing with the performance of a zero-forcing precoder through simulations.

並列關鍵字

Ultra dense networks ； Small cell ； CoMP ； Proportional Fair resource allocation

參考文獻

[1] M.Kamel, W.Hamouda, and A.Youssef, “Ultra-Dense Networks : A Survey,” IEEE Commun. Surv. Tutorials, vol. 18, no. 4, pp. 2522–2545, 2019.

[2] “The METIS 2020 Project – Laying the foundation of 5G.” [Online]. Available: https://metis2020.com/.

[3] R.Baldemair et al., “Ultra-dense networks in millimeter-wave frequencies,” IEEE Commun. Mag., vol. 53, no. 1, pp. 202–208, Jan.2015.

[4] X.Wang, E.Visotsky, and A.Ghosh, “Dynamic cell muting for ultra dense indoor small cell deployment scenario,” in 2015 IEEE International Conference on Communication Workshop (ICCW), 2015, pp. 148–153.

[5] A.Hajisami and D.Pompili, “Dynamic joint processing: Achieving high spectral efficiency in uplink 5G cellular networks,” Comput. Networks, vol. 126, pp. 44–56, Oct.2017.