A brief survey of radio access network backhaul evolution: part II

In part I of this article we presented the design alternatives, issues, and challenges for designing backhaul for 2G (GSM, CDMA) and 3G (UMTS, CDMA2000) radio access networks (RANs). Part II extends the survey of backhaul technologies to address LTE-based RANs. We present various alternatives to deal with the specific requirements imposed by Evolved Packet System architecture on the backhaul design. In particular, we address handling of the X2 interface, network security through IPSec, distribution of frequency and phase synchronization, the impact of small cell design, self-organizing networks, and endend QoS management within backhaul. We also present a brief overview of active debates with respect to some of these design options as open issues, in particular the impact of LTE-Advanced requirements on LTE backhaul design.