Performance Evaluation of Frequency Planning in a Novel Cellular Architecture Based on Sector Relay
ABSTRACT To avoid inter-cell interference effectively and to improve the performance of cell-edge users, a novel cellular architecture, termed Cellular Architecture Based on Sector Relay (CASR), is proposed in this paper, and two frequency planning schemes based on CASR are investigated. In CASR, fixed relays equipped with directional antennas are located at the vertex of the hexagonal cell for sectorization, thus each relay can be shared by three cells. The two frequency planning schemes are designed for different situations, one of which focuses more on the performance of cell one-hop users and the other one focuses on the performance balance between one-hop users and two-hop users. Interference analysis and performance evaluation are implemented for both one-hop users and two-hop users. System-level simulation in multi-cell and multi-user environment shows that compared with the existing cellular relay cell architecture, the proposed CASR combined with the two frequency planning schemes yield higher cell spectral efficiency. Moreover, the performance of cell-edge users is significantly improved.
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ABSTRACT: By observing that the relay stations (RSs) will receive a signal replica of the users' transmissions during the broadcast phase, we propose an adaptive relay cooperation scheme. The RSs will utilize the readily available signal replica and the additional diversity naturally inherent in them to either perform cooperative multipoint (COMP) relaying or remain silent with only the direct transmission being considered. We investigate this scheme in a 7 cell network to demonstrate system level capacity and energy efficiency improvements. Results show that the proposed scheme outperforms the conventional adaptive relay scheme and is able to benefit from the more aggressive full bandwidth frequency reuse plan at low relay transmit power.Global Communications Conference (GLOBECOM), 2012 IEEE; 01/2012
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ABSTRACT: A relay cooperation scheme is proposed for the downlink of multicell multiple-input-multiple-output cellular networks. The relay stations (RSs) will cooperatively transmit the signal replicas of all the user equipments obtained during the broadcast phase. We consider different RS decoding strategies during the broadcast phase and joint relay transmission with different degrees of channel state information (CSI) sharing during the relay phase. We also propose the partial semi-orthogonal user selection (PSUS) method designed specifically for relay cooperation. The spectral and energy efficiencies are then evaluated for the relay cooperation scheme. Its cooperative costs for different cooperation levels are also investigated. Simulation results indicate that joint RS decoding outperforms independent RS decoding but a cooperative link with a bit rate of an order of magnitude greater than that achievable by the relay network is required. Compared to the competing user selection methods that require global CSI, the proposed PSUS method utilized for relay phase joint transmission operates at less than half of the cooperative cost while introduces only a slight degradation in system performance.IEEE Transactions on Wireless Communications 10/2013; 12(10):4970-4982. DOI:10.1109/TWC.2013.092013.121692 · 2.76 Impact Factor
Conference Paper: Frequency planning framework for multi-hop OFDMA-based cellular networks[Show abstract] [Hide abstract]
ABSTRACT: In this paper, we consider frequency planning of orthogonal frequency division multiple access (OFDMA) based cellular networks, with two-hop decode-and-forward relay stations (RSs). We develop a new framework for the mathematical modeling of the frequency planning problem, which aims at suppressing multi-links interference and enhancing spectral efficiency. The concept of incidence coloring from modern graph theory is utilized to recast the original frequency planning problem and guide the solution from graph theory perspective.2013 International Conference on Mechatronic Sciences, Electric Engineering and Computer (MEC); 12/2013