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Massive MIMO Transmission in Fronthaul-Constrained Cloud Radio Access Networks : 프론트홀이 제한된 클라우드 기지국에서의 거대 다중안테나 기법
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- Authors
- Advisor
- 박세웅
- Major
- 공과대학 전기·컴퓨터공학부
- Issue Date
- 2015-08
- Publisher
- 서울대학교 대학원
- Keywords
- C-RAN ; cloud radio access network ; massive MIMO ; large-scale antenna system ; fronthau
- Description
- 학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 8. 박세웅.
- Abstract
- To satisfy the ever-increasing capacity demand and quality of service (QoS) requirements of users, massive MIMO (multiple-input multipleoutput) has been attracted as a promising technique in next generation wireless networks. Employing large-scale antennas, however, at remote radio heads (RRHs) generates heavy traffic to be carried through fronthaul links in cloud radio access networks (C-RANs). In this dissertation, we investigate C-RAN architecture, fronthauling methods, and multiple-input multiple-output (MIMO) transmission strategies to overcome explosive fronthaul traffic while maintaining the potential of C-RAN and massive MIMO to the fullest.
Firstly, we proposed a partially-centralized C-RAN (PC-RAN) architecture where precoder, data symbol, and channel state information (CSI) are separately transported in fronthaul links. With the proposed PC-RAN, fronthaul traffic can be remarkably reduced with no or marginal performance degradation, compared with the conventional fully-centralized C-RAN (FC-RAN).
Secondly, we mathematically evaluated the performance of zero-forcing based large-scale MIMO. We derive wireless performance and fronthaul traffic taking account of cooperative processing among RRHs in C-RAN environments. Through extensive simulations, we confirmed the accuracy of our analytical model and provided intuition on trade-off between wireless performance and fronthaul traffic volume.
Thirdly, we investigated a joint beamforming and resource allocation problem of a single RRH for a constrained fronthaul capacity. We provide a heuristic algorithm to decide beamforming configuration and bandwidth allocation for each beamforming technique. The simulation results show that the proposed algorithm further improves the wireless sum-rates and achieves near optimal performance in our proposed partially-centralized C-RANs.
Lastly, we investigated the performance of ZF and MRT with two fronthauling methods in fronthaul-constrained C-RANs. We provide an algorithm to decide the optimal fronthauling method and beamforming strategy to maximize the wireless sum-rate under a limited capacity of fronthaul link. Numerical results confirm that the sumrate gain is greater when both fronthauling solutions are available.
- Language
- English
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