A narrowband approach to efficient PCS spectrum sharing through decentralized DCA access policies

This article addresses spectrum sharing and open access for personal communications services (PCS). Traditional regulation has allocated electromagnetic spectrum through fragmentation into mutually exclusive frequency blocks. Block allocation schemes produce trunking inefficiencies in the use of multiple narrowband RF channels. Broadband allocation schemes such as code division multiple access (CDMA) can accommodate multiple users on a single RF channel. Due to the near-far problem, the only way competing CDMA operators could share common spectrum is through collocation of cell sites, which hinders market mechanisms. An alternative approach is narrowband spectrum sharing through a decentralized dynamic channel assignment (DCA) approach, such as autonomous reuse partitioning (ARP). Multiple-operator DCA allocation schemes for low-tier PCS systems have been proposed in some countries. Under such an approach, competing operators use a common air interface to share the available spectrum. Open access can improve opportunities for competition in the provision of PCS. Other things being equal, a multi-operator DCA system outperforms that achievable by multiple carriers under a traditional fragmented spectrum, even for overlapping networks and unequal traffic loads. In this article we use a discrete event simulation to explore the spectrum efficiency implications of adopting a narrowband decentralized DCA/ARP spectrum-sharing policy. We explore as well regulatory measures so operators will deploy infrastructure instead of appropriating channels from competitors.