Written by: Per Beming, Lars Frid, Göran Hall, Peter Malm, Thomas Noren, Magnus Olsson and Göran Rune

 Download PDF file

LTE-SAE (Long-term evolution - system architecture evolution) systems promise unprecedented performance in new and existing frequency bands for 3GPP and 3GPP2 operators. The simplified and optimized architecture uses a minimum number of nodes in the user plane. In addition, new features have been introduced to simplify operation and maintenance. 

Ericsson's portfolio of base stations and core network products can be upgraded to LTE-SAE, and the company is developing a range of LTE base stations for new deployments. Furthermore, Ericsson's LTE mobile platforms are well positioned for different types of terminals and devices: broadband modules, fixed wireless terminals, and mobile terminals. This combination enables mobile broadband services to everyone, everywhere.


Background and targets

Mobile broadband is rapidly becoming a reality. By 2011, Ericsson anticipates that 1.5 billion people will have broadband. In addition, more than half of these people will have mobile broadband, and the majority of them will be served by HSPA/LTE networks. At present, people can

• surf or send e-mail with HSPA-enabled handsets and notebooks;
• replace their DSL modems with HSPA modems; and
• quickly upload and download videos or music with 3G phones.

LTE, which is to be introduced in 3GPP Release 8, is the next major step in mobile radio communications. It will give a superior user experience and support even more demanding applications, such as interactive TV, user-generated videos, advanced games, and professional services. LTE uses OFDM (orthogonal frequency-division multiplexing) radio access technology together with advanced antenna technologies.

In addition to LTE, 3GPP has specified a flat, IP-based network architecture as part of the system architecture evolution (SAE) effort. The aim and design of the LTE-SAE architecture and concepts are to efficiently support mass-market usage of any IP-based service. The architecture is based on, and evolved from, existing GSM/WCDMA core networks to facilitate simplified operations and smooth, cost-effective deployment.

The LTE-SAE architecture reduces operating expenses (OPEX) and capital expenditures (CAPEX). The new, flat architecture, for example, means that only two node types (base stations and gateways) must scale in capacity in order to accommodate large increases in data volumes. One other area of focus has been network operation functionality, which now targets a high degree of automatic configuration.
In addition, 3GPP and 3GPP2 have agreed to optimize interworking between CDMA and LTE-SAE. CDMA operators will thus also be able to evolve their networks to LTE-SAE and benefit from huge economies of scale and global chipset volumes.

LTE is a versatile technology that fulfills or exceeds 3GPP requirements. Some of the most notable requirements follow below: 

• Downlink peak rates of more than 100Mbps and roundtrip time in the radio access network (RAN) of less than 10ms.
• Support for flexible carrier bandwidths from less than 5MHz up to 20MHz in many new and existing spectrum bands. 
• Support for FDD and TDD deployments. 
• Support for handover and roaming to existing mobile networks, thereby providing ubiquitous coverage to all mobile subscribers from the very outset.

Operators may introduce LTE flexibly, to match current network, spectrum, and business objectives for mobile broadband and multimedia services.