Subject : Mobile Communication

Topic : 4G Wireless Networks

Difficulty : Medium

• LTE stands for Long Term Evolution and it was started as a project in 2004 by telecommunication body known as the Third Generation Partnership Project (3GPP). SAE (System Architecture Evolution) is the corresponding evolution of the GPRS/3G packet core network evolution. The term LTE is typically used to represent both LTE and SAE.

• Long Term Evolution is the next step forward in cellular 3G services. LTE enhanced the Universal Mobile Telecommunication Services (UMTS) in asset of points on account of the future generation cellular technology needs and growing mobile communication services requirements.

• LTE evolved from an earlier 3GPP system known as the Universal Mobile Telecommunication System (UMTS) which is turn evolved from the Global System of Mobile Communication. Even related specifications were formerly known as the evolved UMTS terrestrial radio access (E-UTRA) and evolved UMTAS terrestrial radio access network (E-UTRAN). First version of LTE was documented in Release 8 of the 3GPP specifications.

• A rapid increase of mobile data usage and emergence of new applications such as MMOG (Multimedia Online Gaming), mobile TV, Web 2.0, streaming contents have motivated the 3rd Generation Partnership Project (3GPP) to work on LTE on the way towards 4th Generation mobile.

• LTE offers a reduced latency delay, which is achieved with a simplified flat radio infrastructure in which some of the functions have been moved from the Radio Network Controller (RNC) to the evolved NodeB (eNB)

• Another design goal is to increase spectrum efficiency and as such as a better cost per bit ratio and better service provisioning.

• Increased data rates will be realized the including the support of multi antenna techniques and in combination with techniques such as Orthogonal Frequency Division Multiplexing (OFDM). It will offer the flexibility in spectrum deployment and provide higher robustness against frequency selective fading for the system.

• The main goal of LTE is to provide a high data rate, low latency and packet optimized radio access technology supporting flexible bandwidth deployments.

Facts/Objective/details of LTE

• LTE is the successor technology not only of UMTS but also of CDMA 2000.

• LTE is important because it will bring up to 50 times performance improvement and much better spectral efficiency to cellular networks.

• LTE introduced to get higher data rates, 300Mbps, peak downlink and 75Mbps peak uplink. In a 20Mhz carrier data rates beyond 300Mbps can be achieved under very good signal conditions.

• LTE is an ideal technology to support high data rates for the services such as VoIP. Streaming multimedia, video conferencing or even high speed cellular modem.

• LTE uses both Time Division Duplex (TDD) and Frequency Division Duplex (TDD) mode. In FDD uplink and downlink transmission used different frequency, while in TDD both uplink and downlink use the same carrier and same separated in time.

• LTE supports flexible carrier bandwidths, from 1.4Mhz up to 20Mhz as well as both FDD and TDD. LTE designed with a scalable carrier bandwidth from 1.4Mhz up to 20Mhz which bandwidth is used depends on the frequency band and the amount of spectrum available with a network operator.

• All LTE devices have to support (MIMO) Multiple Input and Multiple Output transmissions, which allow the base station to transmit several data streams over the same carrier simultaneously.

• All interfaces between network nodes in LTE are now IP based, including the backhaul connection to the radio base stations. This is great simplification compared to earlier technologies that were initially based on E1/T1, ATM and frame relays links, with most of them being narrowed and expensive.

• Quality of Service(QoS) mechanism have been standardized on all interfaces to ensure that the requirement of voice calls for a constant delay and bandwidth can still met when capacity limits are reached.

• Works with GSM/EDGE/UMTS systems existing 2G and 3G spectrum and new spectrum. Supports hand-over and roaming to existing mobile networks.