Naoki Kusashima

Fractional Base Station Cooperation Cellular Network

In modern cellular systems, high-rate communication is performed using MIMO transmission by a Single Base Station (BS). This method is able to improve the transmission rate when the user is at the cell-inner. However the rate severely degrades when the user is located at cell-edge. Base Station Cooperation (BSC) MIMO is solve the cell-edge problem. BSC MIMO can improve capacity at the cell-edge than FFR or TAA cancellation, however, it has minimal impact on cell-inner users and increases complexity of the network. In this paper, Fractional Base Station Cooperation Cellular Network (FBSC-CN) is proposed in which a combination of Single BS MIMO and BSC Multiuser (MU) MIMO is performed in order to achieve gains both at the cell-inner and cell-edge with limited complexity. Furthermore, by cooperating with each BS autonomously and distributedly, cooperative BSs are able to select the most suitable transmission schemes to the users accordingly.

Dynamic cooperation set clustering on base station cooperation cellular networks

Base station cooperation (BSC) has been identified as a key radio access technology for next-generation cellular networks such as LTE-Advanced. BSC maximizes its gains over non-cooperation (NC) in a network wherein interference from cooperating BSs is the main limitation. However, at locations where the signals from non-cooperating BSs are the dominant interference, the gains are minimal. Therefore, for every user equipment, the set of cooperating BSs must be properly selected in order to achieve the potential gains of BSC in a cellular network. In this paper, various BSC cluster types and cell regions are introduced, and the impact of dynamic clustering on BSC spectral efficiency is discussed. It is shown that to maximize the spectral efficiency gains of BSC multi-user MIMO to a UE, the BSs which induce the strongest received signal powers must be selected for cooperation. Simulation results show that by performing dynamic clustering, the geographical area at which BSC achieves better spectral efficiency over NC can be significantly increased over that of static clustering.

Impact of base station cooperation on cell planning

Base station cooperation (BSC) has been identified as a key radio access technology for next-generation cellular networks such as LTE-Advanced. BSC impacts cell planning, which is the methodical selection of base station (BS) sites, and BS equipment configuration for cost-effective cellular networks. In this paper, the impact of BSC on cell plan parameters (coverage, traffic, handover, and cost), as well as additional cell planning steps required for BSC are discussed. Results show that BSC maximizes its gains over noncooperation (NC) in a network wherein interference from cooperating BSs is the main limitation. Locations exist where NC may produce higher throughputs, therefore dynamic or semistatic switching between BSC and NC, called fractional BSC, is recommended. Because of interference from noncooperating BSs, the gains of BSC over NC are upper bounded, and diminishes at greater intersite distances because of noise. This encourages smaller cell sizes, higher transmit powers, and dynamic clustering of cooperative BSs.