LTE Introduction

Copyright © 2011, [email protected]

1

LTE Introduction

0056532 Tzu-chin Liu15th March 2012


2

Outline

• Overview• Network architecture• Protocol stack• Resource element• Frame structure

– TDD frame configuration– TDD special subframe

• MIMO• Random access procedure


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LTE Overview

• LTE – Long Term Evolution: The 4th generation telecommunication standards.– Evolved from the 3GPP system.(R8)– RAN: LTE– Core: SAE(System Architecture Evolution)

• Characteristics:– Packet switching– All – IP network– Higher data rate– OFDMA based– MIMO supported


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SAE – System Architecture Evolution


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Protocol Stack• User plane:

• Control plane:


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Resource element

• The basic unit when allocating carrier resource.

• Resource Element(RE):– One subcarrier by one

symbol• Resource Block(RB):

– 12 subcarriers by 7 symbol

• Resource Element Group(REG):– For control plane– One REG has 4 or 6

REs.


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LTE Frame Structure

• One radio frame has 10 ms:– 10 subframes, each

of 1 ms.• Duplexing:

– FDD– TDD


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LTE TDD Frame

• UL-DL configuration:– LTE TDD can have 7

UL-DL subframe configurations.

• Special Subframe:– Provide a gap to allow

switching from DL to UL a transition subframe.


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LTE TDD UL-DL configuration


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MIMO

• Multiple-Input Multiple-Output: – multiple antennas at

both the transmitter and receiver to improve communication performance.

• Better throughput• Longer transmission

distance


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MIMO modes

• Downlink Transmission Mode:– Release 8 have defined 7 transmission modes.


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Random Access Procedure

• Random access purpose: Set up the RRC (Radio Resource Control) connection when:– Idle state or initial power on– Handover– Synchronization– Reset RRC


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Random Access Procedure


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Q & A


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References

• TDD LTE Air Interfaces v.1• TS 33.401 3GPP System Architecture Evolution (SAE):

Security architecture • TS 36.213 Evolved Universal Terrestrial Radio Access

(E-UTRA); Physical layer procedures • TS 36.321 Evolved Universal Terrestrial Radio Access

(E-UTRA); Medium Access Control (MAC) protocol specification

LTE Introduction

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