Power Control for 5G User-Centric Network: Performance Analysis and Design Insight

User-centric network (UCN), which organizes a dynamic transmission point group (TPG) for each user, is regarded as a promising candidate to meet the exponential growth of mobile data traffic for 5G system. However, the severe interference under dense TP deployment in UCN from co-channel neighbor cell worsens the user performance. In this paper, to combat the fluctuation of user rate, a user-centric power control strategy is proposed, where TPs will take power control coefficient β to effectively mitigate the strong interference for each user within TPG of radius coefficient μ. Based on the strategy, semi-closed expressions of network downlink performance metric are first derived, including coverage probability and average achievable rate to the typical user, and average spectral efficiency of TP with the consideration of the impact of TPG overlapping on the signal link. The TPs and the users are modeled as independent 2-D Poisson point processes. The theoretical analysis confirms that the optimization of β and μ, which determine the area and intensity for power control, respectively, can realize the tradeoff between interference mitigation and resource utilization. Numerical results demonstrate significant performance gains of the user-centric power control strategy in coverage probability, average achievable user rate, and TP spectral efficiency, which can be improved at most by 30%, 15%, and 42%, respectively. In addition, the analysis gives the optimal values of β and μ according to the distance between TP and user.