An Introduction of3GPP Long Term Evolution

(LTE)

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Outline

History of 3GPP LTE Basic Concepts of LTE Introduction of LTE Protocol Compare with LTE and LTE-Advanced Conclusion

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What is LTE ?

In Nov. 2004, 3GPP (3rd Generation Partnership Project) began a project to define the Long-Term Evolution (LTE) of Universal Mobile Telecommunications System (UMTS) cellular technology Higher performance Backwards compatible Wide applications

History of LTE

LTE is a standard for wireless data communications technology and an evolution of the GSM/UMTS standards.

The goal of LTE was to increase the capacity and speed of wireless data networks using new DSP (digital signal processing) techniques and modulations.

A further goal was the redesign and simplification of the network architecture to an IP-based system with significantly reduced transfer latency compared to the 3G architecture.

The LTE wireless interface is incompatible with 2G and 3G networks, so that it must be operated on a separate wireless spectrum.

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History of LTE(Cont’d)

LTE was first proposed by NTT DoCoMo of Japan in 2004, and studies on the new standard officially commenced in 2005.

The LTE standard was finalized in December 2008, and the first publicly available LTE service was launched by TeliaSonera in Oslo and Stockholm on December 14, 2009 as a data connection with a USB modem.

Samsung Galaxy Indulge being the world’s first LTE smartphone starting on February 10, 2011.

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History of LTE(Cont’d)

Initially, CDMA operators planned to upgrade to rival standards called UMB and WiMAX

But all the major CDMA operators (such as Verizon, Sprint and MetroPCS in the United States, Bell and Telus in Canada, au by KDDI in Japan, SK Telecom in South Korea and China Telecom/China Unicom in China) have announced that they intend to migrate to LTE after all.

The evolution of LTE is LTE Advanced, which was standardized in March 2011. Services are expected to commence in 2013.

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Evolution of Radio Access Technologies

LTE (3.9G) : 3GPP release 8~9

LTE-Advanced :3GPP release 10+

802.16d/e

802.16m

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LTE Basic Concepts

LTE employs Orthogonal Frequency Division Multiple Access (OFDMA) for downlink data transmission and Single Carrier FDMA (SC-FDMA) for uplink transmission

SC-FDMA is a new single carrier multiple access technique which has similar structure and performance to OFDMA

A salient advantage of SC-FDMA over OFDM is the low Peak to Average Power (PAP) ratio : Increasing battery life

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LTE Uplink (SC-FDMA)

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Multi-Antenna Techniques

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Generic Frame Structure

Allocation of physical resource blocks (PRBs) is handled by a scheduling function at the 3GPP base station: Evolved Node B (eNodeB)

Frame 0 and frame 5 (always downlink)

Generic Frame Structure (Cont’d)

DwPTS field: This is the downlink part of the special subframe and its length can be varied from three up to twelve OFDM symbols.

The UpPTS field: This is the uplink part of the special subframe and has a short duration with one or two OFDM symbols.

The GP field: The remaining symbols in the special subframe that have not been allocated to DwPTS or UpPTS are allocated to the GP field, which is used to provide the guard period for the downlink-to-uplink and the uplink-to-downlink switch.

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Resource Blocks for OFDMA One frame is 10 ms consisting of 10 subframes One subframe is 1ms with 2 slots One slot contains N Resource Blocks (6 < N < 110)

The number of downlink resource blocks depends on the transmission bandwidth.

One Resource Block contains M subcarriers for each OFDM symbol The number of subcarriers in each resource block

depends on the subcarrier spacing Δf The number of OFDM symbols in each block

depends on both the CP length and the subcarrier spacing.

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LTE Spectrum (Bandwidth and Duplex) Flexibility

LTE Downlink Channels

The LTE radio interface, various "channels" are used. These are used to segregate the different types of data and allow them to be transported across the radio access network in an orderly fashion.

Physical channels: These are transmission channels that carry user data and control messages.

Transport channels: The physical layer transport channels offer information transfer to Medium Access Control (MAC) and higher layers.

Logical channels: Provide services for the Medium Access Control (MAC) layer within the LTE protocol structure.

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LTE Downlink Channels

Paging Channel

Paging Control Channel

Physical Downlink Shared Channel

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LTE Downlink Logical Channels

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LTE Downlink Logical Channels

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LTE Downlink Transport Channel

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LTE Downlink Transport Channel

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LTE Downlink Physical Channels

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LTE Downlink Physical Channels

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LTE Uplink Channels

Random Access Channel

Physical Radio Access Channel

Physical Uplink Shared Channel

CQI report

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LTE Uplink Logical Channels

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LTE Uplink Transport Channel

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LTE Uplink Physical Channels

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LTE Release 8 Key Features (1/2)

High spectral efficiency OFDM in Downlink Single‐Carrier FDMA in Uplink

Very low latency Short setup time & Short transfer delay Short hand over latency and interruption time

Support of variable bandwidth 1.4, 3, 5, 10, 15 and 20 MHz

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LTE Release 8 Key Features (2/2)

Compatibility and interworking with earlier 3GPP

FDD and TDD within a single radio access technology

Efficient Multicast/Broadcast

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Evolution of LTE-Advanced

Asymmetric transmission bandwidth Layered OFDMA Advanced Multi-cell Transmission/Reception

Techniques Enhanced Multi-antenna Transmission Techniques Support of Larger Bandwidth in LTE-Advanced

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Asymmetric Transmission Bandwidth

Symmetric transmission Voice transmission: UE to UE

Asymmetric transmission Streaming video : the server to the UE (the downlink)

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Layered OFDMA

The bandwidth of basic frequency block is, 15 - 20 MHz

Layered OFDMA comprises layered transmission bandwidth assignment (bandwidth is assigned to match the required data rate), a layered control signaling structure, and support for layered environments for both the downlink and uplink.

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Coordinated Multi-Point Transmission/Reception (CoMP)

The CoMP is one of the candidate techniques for LTE-Advanced systems to increase the average cell throughput and cell edge user throughput in the both uplink and downlink.

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Enhanced Multi-Antenna Transmission Techniques

In LTE-A, the MIMO scheme has to be further improved in the area of spectrum efficiency, average cell through put and cell edge performances

In LTE-A the antenna configurations of 8x8 in DL and 4x4 in UL are planned

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Enhanced Techniques to Extend Coverage Area

Remote Radio Requirements (RREs) using optical fiber should be used in LTE-A as effective technique to extend cell coverage

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Support of Larger Bandwidth in LTE-Advanced

Peak data rates up to 1Gbps are expected from bandwidths of 100MHz. OFDM adds additional sub-carrier to increase bandwidth

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LTE vs. LTE-Advanced

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Conclusion

LTE-A helps in integrating the existing networks, new networks, services and terminals to suit the escalating user demands

LTE-Advanced will be standardized in the 3GPP specification Release 10 (LTE-A) and will be designed to meet the 4G requirements as defined by ITU