sheng lung cheng department of communication engineering national chiao tung university 2011 10 17
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Sheng-Lung Cheng Department of Communication Engineering National Chiao Tung University 2011-10-17. The Study Report of LTE Physical Layer Documents. Outline. Introduction References DL/UL transmission train Discussible topics. Introduction.

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sheng lung cheng department of communication engineering national chiao tung university 2011 10 17
Sheng-Lung Cheng

Department of Communication Engineering

National Chiao Tung University

2011-10-17

The Study Report of LTE Physical Layer Documents
outline
Outline
  • Introduction
  • References
  • DL/UL transmission train
  • Discussible topics
slide3

Introduction

  • The goal of LTE is to provide a high-data-rate, low-latency

and packet-optimized radioaccesstechnology supporting

flexible bandwidthdeployments.

  • LTE system attributes
slide4

Reference

  • Farooq Khan ,“LTE for 4G Mobile Broadband: Air Interface Technologies and Performance References”, Cambridge , 2009-04-19.
  • Erik Dahlman, Stefan Parkvall, Johan Skold ,“4G: LTE/LTE-Advanced for Mobile Broadband”, Academic Press , 2011-05-09.
  • 3GPP TS 36.211: "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation".
  • van de Beek, J.J.; Sandell, M.; Borjesson, P.O.” ML estimation of time and frequency offset in OFDM systems ”, IEEE Transactions Signal Processing, 1800 – 1805, Jul 1997.
slide6

DL/UL system model

  • Frame structure(type1 for FDD and half-duplex FDD)
slide8

By applying different scrambling sequences for neighboring cells, the interfering signal after descrambling is randomized, ensuring full utilization of the processing gain provided by the channel code.

DL/UL system model

  • Overview of downlink physical channel processing.
slide9

DL/UL system model

  • Overview of uplink physical channel processing.
slide10

DL/UL system model

  • Downlink layer mapping

(A)

(B)

slide11

DL/UL system model

  • Downlink layer mapping

(C)

slide12

DL/UL system model

  • Downlink layer mapping

The rank assignment refers to RI

slide13

DL/UL system model

  • Downlink precoding

(A)

(B)

(1)

slide14

DL/UL system model

The precode matrix assignment refers to

PMI

  • Downlink precoding
slide15

DL/UL system model

  • Downlink precoding

Here the W(i) is not selected by UE.

(2)

slide16

DL/UL system model

  • Downlink precoding

(C)

Precoding for transmit diversity

Antenna Port

Freq. Band

slide17

Antenna Port

Freq. Band

DL/UL system model

  • Downlink precoding
slide18

Discussible topics

  • Initial cell search
slide19

Discussible topics

  • Initial cell search
slide20

Discussible topics

  • Initial cell search

??

OFDM symbol timing synchronization

FD PSS

Radio frame timing synchronization

Cell ID determination

FD PSS and SSS

a. Using TD PSS

The length 62 FD Zadoff–Chu (ZC) sequence has bad TD performance when IFFT size is large.

slide21

Discussible topics

  • Initial cell search

a. Using CP

slide22

Discussible topics

  • Initial cell search

Downlink CRS in one antenna transmission

Some OFDM symbols may not have any data, so the observation interval would be very large.

slide23

Discussible topics

  • DCI (Downlink Control Information) blind detection

Downlink control information , DCI, provides the terminal with the necessary information for proper reception and decoding of the downlink data transmission.

Puncturing or repetition

Control-Channel Elements (CCEs), is a convenient name for a set of 36 useful resource elements. The number of CCEs, 1, 2, 4, or 8, required for a certain PDCCH depends on the DCI payload channel-coding rate.

slide24

Discussible topics

  • DCI blind detection

As the number of CCEs for each of the PDCCHs may vary and is not signaled, the terminal has to blindly determine the number of CCEs used for the PDCCH it is addressed upon.

In release 8/9, the number of blind decoding attempts is 44 per subframe, while for release 10 with uplink spatial multiplexing the number is 60.

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