Heterogeneous Cellular Networks

10

Cell Selection Modes in LTE Macro–Femtocell Deployment

Meryem Simsek and Andreas Czylwik

University of Duisburg-Essen, Germany

10.1 Introduction

Long Term Evolution (LTE) is the next major step in mobile radio communications and was introduced in 3rd Generation Partnership Project (3GPP) Release-8. In addition to LTE, the 3GPP has also defined IP-based flat network architecture. This architecture is defined as part of the System Architecture Evolution (SAE) effort. Since the LTE/SAE is based on a flat all-IP architecture, the architecture and interfaces are the same for femtocells (HeNBs) as for macrocells (eNBs). LTE femtocells require no new interfaces to be defined and no changes are required to the Evolved Packet Core (EPC), which is the main element of the LTE/SAE network. The EPC is defined in 3GPP Release-8 and is integral to the industry drive towards flatter, all-IP networks. The EPC supports local breakout of traffic whether a roaming subscriber is accessing the EPC via a 3GPP-based or a non-3GPP-based access network according to the design principles described in [1]. Specific EPC components include the Mobility Management Entity (MME) in the control plane and the Serving Gateway (SGW) and Packet Data Network Gateway (PGW) in the bearer plane. The MME is the control node that processes the signalling between the User Equipment (UE) and the Core Network (CN). The protocols running between the UE and the CN are known as the Non Access Stratum (NAS) protocols. Among ...