Thursday, 19 April 2012

What is lte?


Long Term Evolution (LTE), is a radio platform technology . LTE uses Orthogonal Frequency Division Multiple Access (OFDMA) on the downlink, which is well-suited to achieve high peak data rates in high spectrum bandwidth. LTE is part of the GSM evolutionary path for mobile broadband, following EDGEUMTSHSPA (HSDPA and HSUPA combined) and HSPA+.

In the same way that 3G coexists with second generation (2G) systems in integrated networks, LTE systems will coexist with 3G systems as well as 2G systems. Multimode devices will function across LTE/3G or even LTE/3G/2G, depending on market circumstances.

What does LTE provide?
  • Peak theoretical downlink throughput rates of 326 Mbps in a 20 MHz bandwidth channel with 4X4 MIMO and 86 Mbps uplink in 20 MHz
  • Operation in both FDD and TDD modes
  • Scalable bandwidth up to 20 MHz, covering 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz in the study phase
  • An increase in spectral efficiency of two to four times that of HSPA Release 6
  • Reduced latency to 10 milliseconds (ms) round-trip time between user equipment and the base station and to less than 100 ms transition time from inactive to active
 
 What are the main benefits of LTE? 
A simplified, flat architecture from an all IP, packet-based network helps to reduce both latency and cost for LTE. The OFDM technology used by LTE also serves to lower operators' equipment costs. The technology also uses a worldwide standard that has garnered broad support from operators across the globe.

An important feature of LTE is the amount of flexibility it allows operators in determining the spectrum in which it will be deployed. Not only will LTE have the ability to operate in a number of different frequency bands (so operators will be able to deploy it at lower frequencies with better propagation characteristics) but it also features scalable bandwidth. Whereas UMTS/HSPA uses fixed 5 MHz channels, the amount of bandwidth in an LTE system can be scaled from 1.25 to 20 MHz. This means networks can be launched with a small amount of spectrum, alongside existing services, and adding more spectrum as users switch over. It allows operators to tailor their network deployment strategies to fit their available spectrum resources and not have to make their spectrum fit a particular technology.

LTE will increase spectral efficiency over Rel-6 HSDPA by a factor of two to four, approaching 2 bps/Hz in the downlink and 1 bps/Hz in the uplink in ideal conditions.

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