LTE-A: Trailblazing Towards 4G

In a new report entitled 4G LTE Revenue Opportunities, Juniper Research forecasts that by 2014, revenue generated by LTE mobile networks will exceed $100 billion U.S. globally. These revenues will be driven by laptops, smartphones, and other devices with a large proportion of revenues deriving from high traffic subscribers using web, email, and video. For this reason, mobile operators are now speeding up LTE commercialization. GSA’s report Evolution to LTE (August 2010) details 101 LTE network commitments in 41 countries.

After two years of standardization, the first release of LTE-A Rel-10 will be frozen in March 2011. LTE-A provides larger bandwidth, higher spectrum efficiency, and higher peak data rates than LTE. Performance is optimized in urban hotspots, cell edges, and heterogeneous network environments, enabling seamless coverage from macro cells to indoors areas.  LTE-A is highly compatible with LTE and introduces key techniques that meet and exceed ITU requirements for 4G. It can therefore be regarded as a real 4G standard. 

Carrier Aggregation                  

In wireless communications, spectrum is a highly valuable resource and accounts for considerable OPEX. Many operators own several continuous or non-continuous spectrum resources, and capitalizing on these resources has been their focus of attention. To address the frequency bottleneck, Carrier Aggregation (CA) has been introduced into LTE-A. CA supports aggregation of both continuous and non-continuous carriers, as shown in Figure 1. Continuous carrier aggregation is used for super-high bandwidth. Non-continuous carrier aggregation has a much wider range of applications than continuous carrier aggregation. Because spectrum is usually scattered on various frequency bands, and many discrete small-bandwidth spectrum resources are released when 2G/3G networks evolve to 4G, aggregating these scattered spectrum resources is important.

Coordinated Multi-Point Tx/Rx

With the emergence of new services such as Local by Social (LBS) and popularity of multimedia terminals, wireless services can be accessed anywhere and at anytime. However, communication quality can be affected by multicell interference and can be dramatically reduced at cell edges. Coordinated Multi-Point Tx/Rx (CoMP) significantly improves cell-edge user throughput by employing multicell coordination, as illustrated in Figure 2. Users can access smooth and fast Internet whether they are in cell centre or at the cell edge.

Enhanced MIMO

Multi-Input Multi-Output (MIMO) improves signal quality and spectral efficiency using multiple antennas for transmission and reception. Compared with LTE, LTE-A supports up to four transmit antennas in the uplink and the number of transmit antennas is expanded from four to eight in the downlink (see Figure 3). This greatly improves spectrum efficiency and transmission quality.

Wireless Relay

Coverage in remote areas has been a hard nut to crack in wireless communications. An effective solution is to introduce a relay node or relay station between eNB and UE, as shown in Figure 4. The relay node is connected to eNB via a wireless link. This reduces network deployment cost considerably. Moreover, relay can improve high data rate coverage in urban hotspots, provide coverage in blind areas, and support group mobility and temporary network deployment.

LTE-A has complete 4G technical features, and its standards and techniques have been thoroughly researched. Since LTE-A requirements were first put forward, ZTE has taken an active part in drafting LTE-A standards and submitting proposal that have been adopted by 3GPP. Presently, a number of LTE-A issues are being worked through, and various standards are being perfected.

ZTE successfully demonstrated an LTE-A system at the P&T/Expo Comm China in October 2010. Visitors to the expo witnessed a download peak rate of 1Gbps delivered by 4G technology. 

ZTE is now working hard to develop LTE-A technology and has made good inroads to this end. The company plans to roll out commercial LTE-A products in 2012. This will allow people to enjoy feature-rich services and high-speed connectivity using mobile broadband.