Long Term Evolution (LTE) – The 4G Mobile Broadband Standrard

Mobile broadband is becoming a reality, as the internet generation grows accustomed to having broadband access wherever they go and not just at home or in the office. Of the estimated 3.4 billion people who will have broadband by 2014, about 80 percent will be mobile broadband subscribers – and the majority will be served by High Speed Packet Access (HSPA) and Long Term Evolution (LTE) networks.

Long Term Evolution (LTE) is the project name of a new high performance air interface for cellular mobile communication systems. LTE is marketed as 4th Generation (4G) of radio technologies designed to increase the capacity and speed of mobile telephone networks. LTE is the natural upgrade path for GSM to 4G. Long Term Evolution offers a superior user experience and simplified technology for next-generation mobile broadband.

People can already browse the internet or send e-mails using HSPA-enabled notebooks, replace their fixed DSL modems with HSPA modems or USB dongles and send and receive video or music using 3G phones. With LTE, the user experience will be even better. It will enhance more demanding applications such as interactive TV, mobile video blogging, advanced games and professional services.

Long Term Evolution (LTE) is the next major enhancements to the Universal Mobile Telecommunications System (UMTS), which is introduced in 3rd Generation Partnership Project (3GPP). The 3GPP is a collaboration agreement, established in December 1998, which brings together a number of telecommunications standards bodies, known as organizational partners.

LTE uses orthogonal frequency division multiplexing (OFDM) as its radio access technology, together with advanced antenna technologies.

Researchers and development engineers from all over the world – representing operators, vendors and research institutes – are participating in the joint LTE radio access standardization effort.

The LTE specification provides downlink peak rates of at least 100 Mbps, an uplink of at least 50 Mbps and Radio access network (RAN) round-trip times of less than 10 ms. LTE supports scalable carrier bandwidths, from 20 MHz down to 1.4 MHz.

The main advantages with LTE are high throughput, low latency, plug and play, improved end-user experience and simple architecture resulting in low operating costs. LTE will also support seamless passing to cell towers with older network technology such as GSM, cdmaOne, W-CDMA (UMTS), and CDMA2000.

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Some of the world’s leading operators, vendors and research institutes have joined forces in the Next Generation Mobile Networks (NGMN) program. The NGMN program works alongside existing standardization bodies and has established clear performance targets, fundamental recommendations and deployment scenarios for a future wide-area mobile broadband network.

A number of broadband applications are significantly enhanced with mobility. Community sites, search engines, presence applications and content-sharing sites such as YouTube are a few examples. With mobility, these applications become significantly more valuable to users. User-generated content is particularly interesting, because it changes traffic patterns, making the ability to uplink more important than ever. The high peak rates and short latency of LTE also enable real-time applications such as gaming and video-conferencing.

In addition to LTE, the 3GPP is also defining an IP-based, fiat network architecture. This architecture is defined as part of the System Architecture Evolution (SAE) effort. The LTE–SAE architecture and concepts have been designed for efficient support of mass market usage of any IP-based service. The architecture is based on an evolution of the existing GSM/WCDMA core network, with simplified operations and smooth, cost-efficient deployment.

Work has also been done via cooperation between the 3GPP and 3GPP2 (the CDMA standardization body) to optimize interworking between CDMA and LTE–SAE. This means that CDMA operators will be able to evolve their networks to LTE–SAE and enjoy the economies of scale and global chipset volumes that have been such outstanding advantages for GSM and WCDMA.

LTE supports fiexible carrier bandwidths, from 1.4MHz up to 20MHz. LTE also supports frequency division duplexing (FDD) and time division duplexing (TDD). FDD is more efficient and represents higher device and infrastructure volumes, but TDD is a good complement. Fifteen paired and eight unpaired spectrum bands have already been identified by the 3GPP for LTE. LTE radio network products will have a number of features to help simplify the building and management of next-generation networks.

All current cellular systems use FDD and more than 90 percent of the world’s available mobile frequencies are in paired bands. With FDD, downlink and uplink traffic is transmitted simultaneously in separate frequency bands. With TDD, the transmission in uplink and downlink is discontinuous within the same frequency band.

In addition to mobile phones, many computer and consumer electronic devices, such as notebooks, ultra-portables, gaming devices and cameras, will incorporate embedded LTE modules. Because LTE supports handover and roaming to existing mobile networks, all these devices can have ubiquitous mobile broadband coverage from day one.

LTE meets and in some cases exceeds the targets for peak data rates, cell edge user throughput and spectrum efficiency, as well as VoIP and Multimedia Broadcast Multicast Service (MBMS) performance.

Summary of the 3GPP original LTE requirements

  • Increased peak data rates: 100Mbps downlink and 50Mbps uplink.
  • Reduction of RAN latency to 10ms.
  • Improved spectrum efficiency (two to four times compared with HSPA Release 6).
  • Cost-effective migration from Release 6 Universal Terrestrial Radio Access (UTRA) radio interface and architecture.
  • Improved broadcasting.
  • IP-optimized (focus on services in the packet-switched domain).
  • Scalable bandwidth of 20MHz, 15MHz, 10MHz, 5MHz, 3MHz and 1.4MHz.
  • Support for both paired and unpaired spectrum.
  • Support for inter-working with existing 3G systems and non-3GPP specified systems.

The first LTE network infrastructure and terminal products will support multiple frequency bands from day one, meaning LTE will be able to quickly reach high economies of scale and global coverage. Eventually LTE will be deployed in all cellular bands. Unlike other earlier cellular systems, LTE will be quickly deployed on multiple bands.

Terminals, modules and fixed wireless terminals

By the time LTE is available, mobile broadband devices will be mass market products. Industry analyst Informa recently forecast that by 2013 there will be about 900 million WCDMA devices sold annually and more than 75 percent of them will be HSPA-enabled.

Today, most people think “mobile phones” when mobile connections are discussed. But in the coming years, devices such as notebooks, ultra-portables, gaming devices and video cameras will operate over existing mobile broadband technologies such as HSPA and CDMA2000, as well as LTE through standardized mobile broadband modules.

Many companies in the consumer electronics business will be able to deploy mobile broadband technology cost-effectively to further enhance the user value of their offerings.

Mobile Broadband Routers (MBRs) offer another opportunity to use mobile broadband efficiently. MBRs can be compared to fixed DSL modems with Ethernet, WLAN or POTS connections for devices at home or in the office. The main difference is that the broadband service is not carried over copper cables, but through the radio network. MBRs enable operators to provide broadband service cost-efficiently to all users who already have desktop computers with Ethernet connections or notebooks with WLAN connectivity.

Cost efficiency

One of the key success factors for any technology is economy of scale. The volume advantage is beneficial for both handsets and infrastructure equipment. It drives down the manufacturing costs and enables operators to provide cost-efficient services to their customers.

Deployment of LTE will vary from country to country, according to regulatory requirements. The first devices will be multimode-based, meaning that wide-area coverage, mobility and service continuity can be provided from day one.

It is important that the deployment of LTE infrastructure is as simple and cost-efficient as possible. For example, it should be possible to upgrade existing radio base stations to LTE using plug-in units, so they become both dual mode and dual band.

Conclusion

LTE is well positioned to meet the requirements of next-generation mobile networks, both for existing 3GPP/3GPP2 operators and greenfielders. It will enable operators to offer high-performance, mass market mobile broadband services, through a combination of high bit-rates and system throughput, in both the uplink and downlink and with low latency.

LTE infrastructure is designed to be simple to deploy and operate, through fiexible technology that can be deployed in a wide variety of frequency bands. LTE offers scalable bandwidths, from 1.4MHz up to 20MHz, together with support for both FDD paired and TDD unpaired spectrum. The LTE–SAE architecture reduces the number of nodes, supports fiexible network configurations and provides a high level of service availability. LTE–SAE will also inter-operate with GSM, WCDMA/HSPA, TD-SCDMA and CDMA.

LTE will be available not only in next-generation mobile phones, but also notebooks, ultra-portables, cameras, camcorders, MBRs and other devices that benefit from mobile broadband.

[Reference: LTE Intro – Ericsson]

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