Difference Between UTRAN and eUTRAN


UTRAN (Universal Terrestrial Radio Access Network) and eUTRAN (Evolved Universal Terrestrial Radio Access Network) are both Radio Access Network Architectures, which consist of Air Interface Technology and Access Network Node Elements. UTRAN is the 3G UMTS (Universal Mobile Telecommunication System) radio access network that was introduced in 3GPP (Third Generation Partnership Project) Release 99 in year 1999 while eUTRAN is the LTE (Long Term Evolution) rival of it, which was introduced in 3GPP Release 8 in year 2008.

What is UTRAN?

UTRAN consists of UTRA (Universal Terrestrial Radio Access) or in other words, Air Interface Technology, which includes WCDMA (Wideband Code Division Multiple Access), RNC (Radio Network Controller), and Node B (3G UMTS Base Station). Normally RNC is located in a centralized location connecting many Node Bs into a one RNC. The RRC (Radio Resource Control) function is implemented by both RNC and Node B together. UTRAN is a combined architecture of both CS (Circuit Switched) and PS (Packet Switched) network.

The external interfaces of UTRAN are IuCS that connects with CS Core Network, IuPS that connects with PS Core Network, and Uu interface, which is air interface between UE and Node B. More specifically, IuCS control plane connects with MSC Server, IuCS user plane connects with MGW (Media Gateway), IuPS control plane connects with SGSN, and IuPS user plane connects with SGSN or GGSN, depending on Direct Tunnel Implementation. The internal interfaces of UTRAN are IuB that lies between Node B and RNC and IuR that connects two RNCs for Handover purposes.

What is eUTRAN?

The eUTRAN consists of eUTRA (Evolved Universal Terrestrial Radio Access) or, in other words, Air Interface Technology which includes OFDMA (Orthogonal Frequency Division Multiple Access) and eNode Bs (Evolved Node B). Here, both RNC and Node B functions are done by eNode B and it moves all RRC processing towards Base Station end. eNode Bs are providing the eUTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE. Most important factor about eUTRAN is that it has a flat architecture of All IP network.

The eNode Bs are interconnected with each other by the X2 interface which is the only internal interface of eUTRAN. S1 interface is used, to connect eNode Bsto the EPC (Evolved Packet Core), and it is the external interface between eUTRAN and Core Network or EPC. The S1 interface can be categorized, more specifically, into S1-MME and S1-U. S1-MME is the one that eNode B connects to the MME (Mobility Management Entity), and S1-U is the one which connects to the Serving Gateway (S-GW). eUTRAN air interface is called as LTE-Uu which lies between UE and eNode B. 

What is the Difference between UTRAN and eUTRAN?

• UTRAN is the Radio Access Network Architecture of 3G UMTS while eUTRAN is that of the LTE.

• UTRAN supports both Circuit Switched and Packet Switch Services while eUTRAN only supports Packet Switch.

• UTRAN Air interface is WCDMA based on spread spectrum modulation technology while eUTRAN has multi-carrier modulation scheme called OFDMA.

• UTRAN has distributed Radio Network function into two network nodes called Node B and RNC, while eUTRAN only contains eNode B which performs a similar function of both RNC and Node B in a single element.

• UTRAN has internal interfaces called IuB, IuR while X2 is the only internal interface of eUTRAN.

• UTRAN has external interface Uu, IuCS andIuPS while eUTRAN has S1 and more specifically S1-MME and S1-U.