Spectrum sharing for frequency hopped CDMA systems with overlaying cellular structures

Abstract

This paper analyzes the uplink capacity of a frequency hopped CDMA system with spectrum sharing between a hot spot microcell embedded in an overlaying macrocell. We investigate how frequency hopping can function together with power control in order to allow the same frequency spectrum to be shared between the two tiers in the CDMA hierarchical cellular system. We consider random frequency hopping (RFH) and dynamic frequency hopping (DFH) combined with three power management methods: 1) signal strength based dynamic power control (PC), 2) static power setting with different maximum transmit power constraints (SPS), and 3) no power control (NPC). Through analysis and simulation, we demonstrate that when employing either the SPS or the PC methods, frequency sharing with DFH outperforms frequency sharing with RFH in terms of system capacity. Both frequency sharing schemes provide larger capacity than splitting frequency band between. macrocells and microcells. However, without using any power management methods, only frequency sharing with DFH can still perform better than the frequency splitting approach. In some cases frequency sharing with RFH may even have lower capacity than frequency splitting.