Pilot power ratio design for hierarchical CDMA systems in supporting multi-class services

Multi-class services change the design paradigm and pose new challenges for the future wireless networks. In the future, a voice-oriented macrocell and a data-oriented microcell will co-exist to support multi-class services. In this paper, we develop an analytical framework to determine the optimal pilot power ratio for the CDMA system considering the impact of hierarchical cellular structure, co-channel interference, shadowing, and multi-class service requirements. An analytical approach for determining the pilot power in the hierarchical cellular system is developed to maximize system capacity in supporting multi-class traffic. Based on this analytical approach, we find that to maximize the system capacity, it is necessary to increase the pilot power of the microcell, but lower the pilot power of the macrocell.