INHA UNIVERSITY

LTE-A Frame Structure

Yang Chamsol

- 2 - INHA UNIVERSITY

Contents

1. Frame Structure2. Uplink3. Downlink

※ Reference - 3GPP TS 36.211: “Physical Channels and Modulation” - 3GPP TS 36.101: “Evolved Universal Terrestrial Radio Access (E-

UTRA);User Equipment (UE) radio transmission and reception”

- 3GPP TS 36.104: “Evolved Universal Terrestrial Radio Access (E-UTRA);Base Station (BS) radio transmission and reception”

- LTE-The UMTS Long Term Evolution from Theory to Practice, Stefania Sesia

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1. Frame Structure

• Basic time unit TS

- TS = 1 / (15000×2048)≈32.5 ns

- significances : 1. OFDM symbols with sampling rate = 15kHz & FFT size = 2048 sampling rate = 15kHz×2048 = 3.072MHz

assuming 2048 FFT size system is efficient BW = 20MHz2. compatibility with UMTS (WCDMA) and 1xEV-DO (CDMA)

TS = (UMTS chip duration) / 8 = (1xEV-DO chip duration) / 25

where UMTS chip duration = 1 / (3.84MHz) 1xEV-DO chip duration = 1 / (1.2288MHz)

• Frame structure types - frame structure type 1 : applicable to FDD (absence for UL-DL

switching) - frame structure type 2 : applicable to TDD (presence for UL-DL

switching)

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1. Frame Structure

• Frame structure type 1 - UL & DL : separated in frequency domain - 1 radio frame = 10ms = 307200TS = 10 subframes = 20 slots

- 1 subframe = 1ms = 30720TS = 2 slots

- 1 slot = 0.5ms = 15360TS

= 7 OFDM symbols (in case of normal CP) = 6 OFDM symbols (in case of extended CP)

#0 #1 #2 #3 #19#18

One radio frame, Tf = 307200Ts = 10 ms

One slot, Tslot = 15360Ts = 0.5 ms

One subframe

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1. Frame Structure

• CP length - cyclic prefix : ensure robustness against ISI

longer than channel impulse response (delay spread) ⇒ large cell → longer CIR / delay spread → longer CP

CP

Subcarrier

spacing(Δf)

CP lengt

hCharacteristic

Normal CP

15kHz 5μs For high mobility

Extended CP

15kHz 17μsLarge suburban and rural cells (large delay spread)

Extended CP

7.5kHz33.3μ

s

For MBSFN (Multimedia Broadcast Single Frequency Network) : multi-cell broadcast transmission mode→ different propagation delay from different BS→ increase CP → large overhead→ reduce Δf to increase number of subcarrier (Δf : 15kHz → 7.5kHz, FFT size : 2048 → 1024)→ sensitive to frequency offset and mobility

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1. Frame Structure

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1. Frame Structure

• Frame structure type 2 - UL & DL : separated in time domain - 1 radio frame = 10ms = 307200TS = 2 half-frames = 10 subframe

- 1 half-frame = 5ms = 153600TS = 5 subframe

- special subframe : DwPTS , GP, UpPTS → DL-to-UL switching point not allow timing advanced UL transmission

DwPTS (downlink pilot time slot), GP (guard period), UpPTS (uplink pilot time slot)

One slot, Tslot=15360Ts

GP UpPTSDwPTS

One radio frame, Tf = 307200Ts = 10 ms

One half-frame, 153600Ts = 5 ms

30720Ts

One subframe, 30720Ts

GP UpPTSDwPTS

Subframe #2 Subframe #3 Subframe #4Subframe #0 Subframe #5 Subframe #7 Subframe #8 Subframe #9

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1. Frame Structure

UL-DL configurati

on

DL-to-UL Switch-point

periodicity

Subframe number

0 1 2 3 4 5 6 7 8 9

0 5 ms D S U U U D S U U U1 5 ms D S U U D D S U U D2 5 ms D S U D D D S U D D3 10 ms D S U U U D D D D D4 10 ms D S U U D D D D D D5 10 ms D S U D D D D D D D6 5 ms D S U U U D S U U D

Uplink-Downlink configuration

- DL-to-UL switch point periodicity : 5ms / 10ms5ms → each half frame contains special subframe10ms → first frame contains special subframe

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1. Frame Structure

Configuration of special subframe (lengths of DwPTS/GP/UpPTS)

Special subframe

configureation

Normal CP in DL Extended CP in DL

DwPTS

UpPTS

DwPTS

UpPTS

Normal CP in UL

Extended CP in UL

Normal CP in UL

Extended CP in UL

0 6592 Ts

2192 Ts 2560 Ts

7680 Ts

2192 Ts 2560 Ts

1 19760 Ts 20480 Ts

2 21952 Ts 23040 Ts

3 24144 Ts 25600 Ts

4 26336 Ts 7680 Ts

4384 Ts 5120 Ts5 6592 Ts

4384 Ts 5120 Ts

20480 Ts

6 19760 Ts 23040 Ts

7 21952 Ts - - -

8 24144 Ts - - -

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1. Frame Structure

Configuration of special subframe (lengths of GP)

Special subframe

configureation

Normal CP in DL Extended CP in DL

Normal CP in UL

Extended CP in UL

Normal CP in ULExtended CP in

UL

0 21936 Ts 21568 Ts 20848 Ts 20480 Ts

1 8768 Ts 8400 Ts 8048 Ts 7680 Ts

2 6576 Ts 6208 Ts 5488 Ts 5120 Ts

3 4384 Ts 4016 Ts 2928 Ts 2560 Ts

4 2192 Ts 1824 Ts 18656 Ts 17920 Ts

5 19744 Ts 19008 Ts 5856 Ts 5120 Ts

6 6576 Ts 5840 Ts 3296 Ts 2560 Ts

7 4384 Ts 3648 Ts 30720 Ts 30720 Ts

8 2192 Ts 1456 Ts 30720 Ts 30720 Ts

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2. Uplink

• Physical channels : set of resource elements carrying information

originating higher layers - PUSCH (Physical Uplink Shared Channel) - PUCCH (Physical Uplink Control Channel) - PRACH (Physical Random Access Channel)

• Physical signals : set of resource elements not carrying information

originating higher layers - Reference signal : DM RS (demodulation reference signal)

SRS (sounding reference signal)

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2. Uplink

• Slot structure and physical resources - resource grid : subcarriers and SC-FDMA symbols , where ,

- resource block : subcarriers (180 kHz) and SC-FDMA symbols (1 slot)

- resource element : 1 subcarrier and 1 SC-FDMA symbol

Channel bandwidth BWChannel [MHz] 1.4 3 5 10 15 20

Transmission bandwidth configuration NRB 6 15 25 50 75 100

<Transmission BW configuration NRB in E-UTRA channel BW> UL

symbNRBscN

Configuration

Normal cyclic prefix 12 7

Extended cyclic prefix 12 6

RBscN

ULsymbN

<Resource block parameters>

UL RBRB scN Nmin,UL UL max,ULRB RB RBN N N

ULsymbN

min,ULRB 6N max,UL

RB 110N

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2. Uplink

ULsymbN SC-FDMA symbols

One uplink slot slotT

0l 1ULsymb Nl

RB

scU

LR

BN

N

subc

arri

ers

RB

scNsu

bcar

rier

s

RBsc

ULsymb NN

Resource block

resource elements

Resource element ),( lk

0k

1RBsc

ULRB NNk

<Uplink resource grid>

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3. Downlink

• Physical channels : set of resource elements carrying information

originating higher layers - PDSCH (Physical Downlink Shared Channel) - PBCH (Physical Broadcast Channel) - PMCH (Physical Multicast Channel) - PCFICH (Physical Control Format Indicator Channel) - PDCCH (Physical Downlink Control Channel) - PHICH (Physical Hybrid ARQ Indicator Channel)

• Physical signals : set of resource elements not carrying information

originating higher layers - Reference signal - Synchronization signal

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3. Downlink

• Slot structure and physical resources - resource grid : subcarriers and OFDM symbols , where ,

- resource block : subcarriers (180 kHz) and OFDM symbols (1 slot)

- resource element : 1 subcarrier and 1 OFDM symbol

DL RBRB scN N DL

symbNmin,DL DL max,DLRB RB RBN N N min,DL

RB 6N max,DLRB 110N

Channel bandwidth BWChannel [MHz] 1.4 3 5 10 15 20

Transmission bandwidth configuration NRB 6 15 25 50 75 100

<Transmission BW configuration NRB in E-UTRA channel BW> DL

symbNRBscN

Configuration

Normal cyclic prefix Δf = 15kHz12

7

Extended cyclic prefixΔf = 15kHz 6

Δf = 7.5kHz 24 3

RBscN

ULsymbN

<Physical Resource block parameters>

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3. Downlink

DLsymbN OFDM symbols

One downlink slot slotT

0l 1DLsymb Nl

RB

scD

LR

BN

N

subc

arri

ers

RB

scNsu

bcar

rier

s

RBsc

DLsymb NN

Resource block

resource elements

Resource element ),( lk

0k

1RBsc

DLRB NNk

<Downlink resource grid>

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Thank you for your audience

Q & A