What is LTE?

01 January 2009 |


Long term evolution (LTE) is the term used to describe the next mobile network standard, which will deliver superfast voice and data connectivity.

The technology, which will be commercially available in 2009, will enhance the mobile broadband user experience – providing additional capacity for the many bandwidth-hungry applications that are developing today including interactive TV, content sharing, advanced real-time gaming and professional services.

LTE is being developed by the Third-Generation Partnership Project (3GPP), and in January 2008 3GPP approved the LTE technology specifications, leading to their inclusion in the forthcoming 3GPP Release 8.

LTE has emerged as the dominant path to 4G networks because it offers a smooth migration from 2G and 3G networks and other radio spectrums (including TV bands) for use in future mobile communication networks. The LTE standard, sometimes referred to as “super 3G”, is specified to provide data rates of at least 100Mbps in the downlink and latency below 10ms. LTE demonstrations have already shown data rates of 160Mbps.

Why is it necessary?

The internet generation is becoming used to having broadband access everywhere. Of the estimated 1.8 billion people who will have broadband by 2012, two-thirds will be mobile broadband consumers – and the majority of them will be served by high speed packet access (HSPA) and LTE networks. Mobile broadband is also becoming the predominant means of delivering internet connectivity in homes, businesses, hospitals and schools in the developing world, where fixed access would be prohibitively expensive to roll out.

Current HSPA networks mean people are already using a variety of internet-enabled applications with mobile broadband-enabled laptops and notebooks. Many users are adopting USB dongles as a means of being connected everywhere. Sharing videos, pictures and downloading music using 3G phones are now commonplace. But as more and more rich, bandwidth-consuming content becomes available, such as HD video, capacity in current networks will become limited. LTE will provide that capacity, and deliver the required user experience.

LTE will also be available in a wider range of terminals to provide much greater connectivity. Already this trend is established in terms of the many HSPA-enabled devices available today. LTE will proliferate in future generations of mobile devices, notebooks, ultra-portables, cameras, camcorders, fixed wireless terminals – and potentially many other devices will carry embedded modems.

Why are carriers looking at LTE?

Carriers are doing business in an increasingly competitive environment, competing not only with other operators, but also with new players such as content providers, and new business models.

However, new business models also mean new opportunities. LTE enables operators to offer high performance, mass-market mobile broadband services built on existing investments in 2G and 3G networks.

Are there alternatives for mobile broadband delivery?

Some carriers have been looking at the development of mobile Wimax as a way to meet the demand for high-bandwidth data services in the precious 2.5GHz and 3.5GHz spectrum bands. Mobile Wimax employs similar techniques as HSPA (the precursor to LTE), which makes its performance comparable in some areas. The two technologies have similar peak data rates and spectral efficiency, for example.

However, with key differences in other areas, they differ in uplink bit rates and coverage. There are also differences in the level of capital expenditure required for network roll-outs. A key success factor for any technology is economy of scale: this is expected to be a major factor favouring LTE where even greenfield operators are expected to benefit.

The latest survey from the GSA reveals there are over 220 commercially deployed HSPA networks already delivering mobile broadband to users in 96 countries: the HSPA and LTE path is establishing itself as the natural choice for most carriers.

How will it be deployed?

LTE will provide operators with flexibility and simplicity in deployment. It offers a choice of carrier bandwidth – from 1.4MHz to 20MHz – and supports both frequency division duplex (FDD) and time division duplex (TDD) access. Ten paired and four unpaired spectrum bands have so far been identified by 3GPP for LTE, and there are more to come. This means that an operator can introduce LTE in “new” bands where it is easiest to deploy 10MHz or 20MHz carriers, and eventually deploy LTE in all bands. LTE radio network products will have a number of features that simplify the building and management of next-generation networks. For example, plug-and-play features and other functions such as self-configuration and self-optimisation will simplify and reduce the cost of network roll-out and management. LTE will be deployed in parallel with simplified, IP-based core and transport networks that are easier to build, maintain and introduce services on. The simple progression will ensure that the next generation of mobile broadband provides ubiquitous coverage for users – and a great business opportunity for mobile carriers.n

John Cunliffe

CTO, Ericsson UK