NAS

Author: Frédéric Firmin, 3GPP MCC

This article gives an overview of the Non-Access Stratum (NAS) and its protocols EMM and ESM.

The Non-Access Stratum is a set of protocols in the Evolved Packet System. The NAS is used to convey non-radio signalling between the User Equipment (UE) and the Mobility Management Entity (MME) for an LTE/E-UTRAN access.

LTE-Advanced

(Submission, June 2013)

In LTE-Advanced focus is on higher capacity:The driving force to further develop LTE towards LTE–Advanced - LTE Release10 was to provide higher bitrates in a cost efficient way and, at the same time, completely fulfil the requirements set by ITU for IMT Advanced, also referred to as 4G.

• Increased peak data rate, DL 3 Gbps, UL 1.5 Gbps
• Higher spectral efficiency, from a maximum of 16bps/Hz in R8 to 30 bps/Hz in R10
• Increased number of simultaneously active subscribers
• Improved performance at cell edges, e.g. for DL 2x2 MIMO at least 2.40 bps/Hz/cell.

LTE

LTE (both radio and core network evolution) is now on the market. Release 8 was frozen in December 2008 and this has been the basis for the first wave of LTE equipment. LTE specifications are very stable, with the added benefit of enhancements having been introduced in all subsequent 3GPP Releases.

The motivation for LTE

• Need to ensure the continuity of competitiveness of the 3G system for the future
• User demand for higher data rates and quality of service
• Packet Switch optimised system
• Continued demand for cost reduction (CAPEX and OPEX)
• Low complexity
• Avoid unnecessary fragmentation of technologies for paired and unpaired band operation

HSPA

By Jeanette Wannstrom

High Speed Packet data Access (HSPA) has been an upgrade to WCDMA networks (both FDD, and TDD) used to increase packet data performance. The introduction was done in steps; High Speed Down Link (DL) Packet data Access (HSDPA), was introduced in 3GPP Release 5, and Enhanced Up Link (UL), also referred to as High Speed UL Packet data Access (HSUPA), came in Release 6.

The combination of HSDPA and Enhanced UL is referred to as HSPA. HSPA evolution (also known as HSPA+ and evolved HSPA) came in Release 7 with further improvements in later releases.

The Evolved Packet Core

Author: Frédéric Firmin, 3GPP MCC

This article looks at the Evolved Packet Core (EPC), the core network of the LTE system, giving an overview of the architecture of the core network, describing some of its key elements.

The EPC is the latest evolution of the 3GPP core network architecture.

In GSM, the architecture relies on circuit-switching (CS). This means that circuits are established between the calling and called parties throughout the telecommunication network (radio, core network of the mobile operator, fixed network). This circuit-switching mode can be seen as an evolution of the "two cans and a string". In GSM, all services are transported over circuit-switches telephony principally, but short messages (SMS) and some data is also seen.