LTE Technology Overview

Constant evolution of mobile networks gives rise to upgrades and new standards. The mobile environment in the last decade has been growing exponentially in the past decade. 3G standards opened the door for mobile phone data usage, created the nest for smartphones and application ecosystem developments, and in turn drove the demand for better quality mobile data transfers. LTE is the next step in mobile technology evolution, created to improve the 3G phone standard to cope with future demand and faster data services. With this in mind, the 3GPP created a project known as 3GPP LTE. Amongst its objectives includes improving spectral efficiencies, lowering costs, making use of newly available spectrum, creating the possibility to refarm, and reallocate spectrum opportunities, and integration with a host of open standards, including those related to Internet Protocol.  LTE uses OFDMA (Orthogonal Frequency Division Multiple Access) in the down link and SCFDMA.

(Single Carrier-Frequency Division Multiple Access)/DFTS-FDMA (Discrete Fourier Transform Spread-Frequency Division Multiple Access) in the uplink. The system supports multiantenna technologies, whose architecture is called EPS (Evolved Packet System), and is comprised of the E-UTRAN (Evolved UMTS Terrestrial Radio Access Network) on the access side, and Evolved Packet Core (EPC) on the core side. Since the air interface and System Architecture Evolution (SAE) of LTE was defined in 3GPP Release 8, there are times this leads to the misconception that LTE is a software upgrade to UMTS/3G.

LTE delivers faster upload and download speeds, lower costs per bit, and new mobile services. 1 Mbps of data over LTE will cost one-fifth less than 1 Mbps of data over UMTS, mainly due to the higher spectral efficiency of LTE. Given a 5 MHz channel bandwidth, LTE will deliver 6bits/Hz compared to 1.2 bits/Hz for HSPA. Technically still dubbed as 3.9 G LTE is capable of delivering peak data rates of up to 100 Mbps on the downlink and 50 Mbps on the uplink, while utilizing a 20 MHz spectrum, with achievable latency levels of as low as 5 ms.  Supplemented by MIMO configurations with 4×4 antennas peak download rates can be increased as much as 300 Mbps. Design targets for LTE include:

  • Instantaneous downlink peak data rate of at least 100 Mb/s within 20 MHz allocation (5 bps/Hz)
  • Instantaneous uplink peak data rate of 50 Mb/s (2.5 bps/Hz within a 20MHz uplink allocation)
  • Downlink: average user throughput per MHz, 3 to 4 times Release 6 HSDPA
  • Uplink: average user throughput per MHz, 2-3 times Release 6 Enhanced Uplink
  • E-UTRAN optimized for low mobile speed: 0-15 km/h. Higher mobile speed between 15-120 km/h should be supported with high performance. Mobility across the cellular network shall be maintained at speeds 120 km/h-350 km/h (or even up to 500 km/h depending on the frequency band)
  • Spectrum flexibility: scalable to operate in 1.4, 3, 5, 10, 15 and 20 MHz allocations: uplink and downlink, paired and unpaired
  • Co-existence with GERAN/3G on adjacent channels; with other operators on adjacent channels; overlapping or adjacent spectrum at country borders; handover with UTRAN & GERAN

LTE radio network products incorporate several features to simplify building and management of next generation networks. Plug-and-play, self configuration and self-optimization simplify and reduce network rollout and management cost.  LTE will be deployed alongside simplified, IP-based core and transport networks that are easier to build, maintain and introduce services on. The 3GPP core network has also undergone System Architecture Evolution (SAE), optimized for packet mode and in particular for the IP-Multimedia Subsystem (IMS) to support all access technologies, including fixed wire-line access. This allows:

  • Improvements in latency, capacity, throughput
  • Simplification of the core network, and optimization for IP traffic and services, and expected growth
  • Simplified support and handover to non-3GPP access technologies

The result is the evolved packet system (EPS) that consists of the core network part, the evolved packet core (EPC) and the radio network evolution part, the evolved UTRAN (E-UTRAN), i.e. LTE. The EPS is also standardized within 3GPP Release 8.

For more information see:

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Analysis of telecom and ICT infrastructure, technologies, and applications.
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