Issues of the radio access network with distributed radio network control functions for Universal Mobile Telecommunication System

This paper introduces the concept and issues to distribute the soft handover (e.g., RNC and MDC) functions from a centralized RAN entity into many entities of a distributed RAN. It also elaborates the reasons for the distribution and the approaches to realize it. The distribution of the soft handover functions keeps the benefit of soft handover and, at the same time, prevents the extra consumption of network resource that a soft handover of the RNC-centralized RAN can incur. The distribution of the function also gives other benefits such as higher network reliability, higher robustness on a given network fault, more flexible network operation and management, and lower combined network costs. This work also introduces the issues of soft handover interoperability among the centralized RAN and the distributed RANs, and between possibly different soft handover solutions inside a distributed RAN.