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
- 3 - INHA UNIVERSITY
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)
- 4 - INHA UNIVERSITY
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
- 5 - INHA UNIVERSITY
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
- 6 - INHA UNIVERSITY
1. Frame Structure
- 7 - INHA UNIVERSITY
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
- 8 - INHA UNIVERSITY
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
- 9 - INHA UNIVERSITY
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 - - -
- 10 - INHA UNIVERSITY
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
- 11 - INHA UNIVERSITY
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)
- 12 - INHA UNIVERSITY
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
- 13 - INHA UNIVERSITY
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>
- 14 - INHA UNIVERSITY
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
- 15 - INHA UNIVERSITY
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>
- 16 - INHA UNIVERSITY
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>
- 17 - INHA UNIVERSITY
Thank you for your audience
Q & A
Top Related