lte vs. 3g
TRANSCRIPT
Radio Frequency TeamEtisalat
Cairo Feb-2014 Mostafa Adawy
LTE Vs. 3G
Work Shop
AgendaLTE Motivation
MIMO Definition
How to calculate HS and LTE throughput
3G Break Stone
LTE Key Performance
3G , LTE and 2G Architecture comparison
LTE Access Technology
LTE Physical Resource and BWs configured
LTE Frame and Multi Path Solutions
LTE channels
UE Measurements in LTE
LTE Motivation
LTE Motivation• LTE Needed for higher data rates and greater spectral efficiency.
• LTE is PS Oriented only (3G deals CS and PS domain).
• LTE enhance the user experience more than the 3G.o LTE user Feel that he is always connected (PS session
establishment takes less than 50 ms and latency 10 ms)o LTE has no state transitions But In 3G we have State transitions.
CoreSignaling connection RRC
Service RAB
3G (HS Connected)3G Idle
There is a Problem when using Smart Phone
HSDPA
Idle
Every time for new connection you need to make new RRC and RAB 3G Solution : I need to Improve the connection time to HS domain
Connected
Idle
Idle
FACH
HSDPA
LTE Motivation (Cont’d)
Core N
Signaling connection RRC
Service RAB
3G Solution is to make state Trans.
PCH
LTE is more simplifiedo LTE user Feel that he is always connected (PS
session establishment takes less than 50 ms and latency 10 ms)
HSPDA HSPDADC
HSPDAMIMO
LTE2*2 MIMO
LTE advance
Throughput
21 Mbps42 Mbps
84 Mbps150 Mbps
3 Gbps
LTE4 * 4 MIMO
300 Mbps
LTE Motivation (Cont’d)
Technology
LTE
MIMO definition
How to calculate LTE throughput
How to calculate HS throughput
High Throughput History
User Data
2 3 5 6 7 841
Bad CQIGood CQI
Low data rateTX Diversity
Poor-------------Radio Environment----------------Good
10 11 13 14 15129
2 3 5 6 7 841
3 5 6 7 841 2 16
ANTENNA A
ANTENNA B
High data rateNo TX Diversity
MULTIPLE INPUT MULTIPLE OUTPUT (MIMO)
SF 8(480 KSps)
SF 2 (1.92 MSps)
SF 1 (3.84 MSps)
SF 4 (960 KSps)
How to calculate the HS Throughput3G Code Tree
SF 16(240 KSps)
HSDPA Works on SF 16
How to calculate the HS Throughput
64 QAM6 b/s
SF 16
HS 15 Code
1 Code in SF 16 = 240 KSps
64 QAM
6 bits per Symbol
HS throughput = 15 Code * 240 KSps. * 6 Bit per Symbol ≈ 21 Mbps Dual Carrier = 21 Mbps * 2 = 42 Mbps
2 * 2 MIMO = 42 Mbps * 2 = 84 Mbps
What is break stone in the 3G
SF 8480 Kbps
SF 2
SF 1
SF 4
SF 16
1 R99 User
1 R99 User
R99 is Break Stone
R99 (killer ) one user R99 will impact the HS (code absorbers)
LTE vs. HSPA+Advantage of LTE over HSPA+
Advantage of HSPA+ over LTE
High Data Rates
Better spectrum efficiency (bits per Hz)
Low latency
Saving CAPEX Simple architecture (no RNCs and BSCs)Lower Cost in managing and maintaining the network (less hardware)LTE use SON (Self Organizing Network)
• Automatic neighbor Relation addition• Self configuring Node-b
HSPA+ is already commercial
LTE is complete new network (HSPA+ is less investment)
LTE UE is expensive
3G , LTE and 2G Architecture & interfaces
IUR
GGSN MSC
SGSN
RNCRNC eNB
MGW CN
eNB
MME SP GWCN
WCDMA LTE
S1 S1
Signaling Data
Node-B
PS + CS PS Domain Only
No RNCs (function is done by eNB) e.g.. call admission
CN is directly connected to access part
LTE is packet oriented ( Over IP ) even Voice
For Voice now we use fall back to 3G
X2eNB eNB
MME
S-GW
Internet
P-GW
Eutran
• Mobility management Entity
S11
S1
LTE Architecture
Connected mode mobility
Radio Recourse Management
Admission control
UL/DL scheduling / HARQ
Measurement and reporting
CN
Signaling
Idle mode mobility
Distribute Paging message to eNB
IRAT handover(connection to other CN)
Keeping QOS
Security , attach and Detach
Roaming
• E node-b
Packet Routing and ForwardingCharging
• Service Gateway
Limit throughput for certain application during hours
IP address allocationDeep packet inspection (Forbid application)
Keep packet and Drop packets Prevent SKYPE , Torrent
Specific Charging for this certain packet
• Packet GateWay
BTS
BSC
NodeB NodeB
RNC RNC
eNB eNB
SP-GW
SGSN
GGSN
MMES11
X2 UP
S1 CP
S1 UP
S3
MMES10Not 3GPP
Wifi
S2
IUR
S4 UP
Abis
Gb
Gn
S4 CP
IUB
IU
X2 CP
Internet
2G 3G LTE
S4 UP
LTE Key Performance
LTE Key Performance
Higher Order Modulation64 QAM
16 QAM
QPSK
1.4 MHz 3 MHz 5 MHz 15 MHz 20 MHz
Scalable BW
Flat IP Arch.
TX
RX
F0 F2 F3 FrequencyF1
MME
New Air Interface Access Tech.
MIMO
LTE Access Technology
Freq. 1
Freq. 2
Freq. 3
Freq. 4
Freq. 5
Freq. 6
Time
Freq.
Time
F1
F2
F3
F4
F5
F6
F1
F2
F3
F4
F5
F6
F1
F2
F3
F4
F5
F6
F1
F2
F3
F4
F5
F6
F1
F2
F3
F4
F5
F6
Time
Freq.
Freq.
Code 1Code 2Code 3Code 4Code 5
FDMA FDMA / TDMA
Power
F1
F2
F3
F4
F5
F6
WCDMA
LTE access Technique
In LTE Lets Remember
Ts
1/Ts 2/Ts 3/Ts 4/Ts 5/Ts-1/Ts-3/Ts -2/Ts-4/Ts
Time
Frequency
S(t)
S(f)
Time Domain
Frequency domain
I need the peak
LTE access Technique (Cont’d)Lets Remember
1/Ts 2/Ts 3/Ts 4/Ts 5/Ts-1/Ts-3/Ts -2/Ts-4/Ts Frequency
Frequency division multiplexing (FDM)• Case 1 (FDM ): Allocation for the pulses on Freq. Band
Peak of one is Zero of the others
F1
F3 F4Frequency
F2
• Case 2 : o Pulse Shaping (Time stretch)o Choose the correct Frequency
Case 2 (OFDM) BW is less than case 1 Case 2 is more BW efficient I can chose frequency so that the peak of one is at the Zeros of the others
F1
F3 F4F2
F5
F7 F8F6
Time
Freq.
Sub Carrier BW = 15 KHz
Symbol
LTE Access Technique (OFDM)
LTE Downlink DL
Slot 1
Time
Freq.
Slot 2
Slot 3
Slot 4
LTE Use OFDM in DL.
Subcarrier BM is 15 KHz.
Number of Subcarrier depend on the BW used.Orthogonal (At sampling point all other carriers are zeros).
LTE Radio access Uplink UL
Slot 1
FFT
Slot 1
Slot 2 Slot 2
Slot 3Slot 3 Slot 3
Single Carrier
Single Carrier
Single Carrier
LTE use OFDM in UL (Single Carrier OFDM)
Subcarrier BM is 15 KHz
Why SC Carrier in ULo To avoid Peak to Average Power Ratio PAPRo Any PA should be operated in the linear region other wise you
will have distortion in the O/P signal
Linear Region
SC 1
SC 2
SC 3
Spike Of Power
Peaks Of Power
Peaks Of Power (PAPR)For DL ( OK )
E-NB has expensive PA sufficient linear region can detail with this peaks
For UL (Not OK) UE is cheap PA can’t detail with this peaks
Slot 1Slot 1FFT
Single Carrier
For UL Convert Subcarriers to Single Carrier (to Avoid PAPR)
Freq.
Time
LTE Radio access Uplink ULSC FDMA
LTE Physical Resource
LTE Radio Physical ResourceResource Element (RE)
Freq.
Time
LTE Time Slot
0.5 ms7 Symbols
1 Sub Carrier( 15 kHz)
LTE Symbol (Contain # of bits)Depend on Modulation
1 Recourse Element 1 subcarrier and 1 Symbol
LTE Radio Physical ResourceResource Block (RB)
Freq.
Time
LTE Time Slot
0.5 ms7 Symbol
1 Recourse block ( RB )o 12 Sub Carrier (15 KHz) * 7 Symbolso 84 Recourse Elemento RB Basic Unit for Transmission of information
12 Sub Carrier
LTE Radio Physical ResourceResource Block (RB)
b
Freq.
Time
Time Slot7 Symbols
0.5 ms
12 Sub Carrier
Symbol
One Recourse block84 Recourse element
LTE Radio Physical ResourceResource Block (RB)
b
Freq.
Time
Time Slot7 Symbols
0.5 ms
12 Sub Carrier
Symbol One Recourse block
12 Sub Carrier *
7
Symbols
84 Recourse
element
One user Take #RBs
o During the DT if you need to check the throughput You check how many RBs assigned for this user #RB increase . Throughput incre. You don’t check how many subcarriers and you don’t check how many symbols Even in counter you check the resource block consumption
Freq.
Time
One Recourse block
12 Sub Carrier *
7
Symbols
84 Recourse
element
One user Take it Time Slot
7 Symbols0.5 ms
One Recourse block
12 Sub Carrier *
7
Symbols
84 Recourse
element
One user Take it
Time Slot7 Symbols
0.5 ms
LTE Scheduler
• LTE Scheduler • 1 User is scheduled every TTI ( 1ms )• Every Schedule instance we have 2 consecutive RBs per user
• Called Scheduled block
Scheduled
BlockSB
LTE Allowed Bandwidths BW
1.4 MHz 3 MHz 5 MHz 15 MHz 20 MHz10 MHz
3GPP define exact BWs used for LTE (fixed) no 18 MHz
You Don’t have to buy new band but you can make band reframing
The more BW you have o Better throughput o More Resource blocks
Band Width MHz Number of RB s1.4 MHz 63.0 MHz 155.0 MHz 2510.0 MHz 5015.0 MHz 7520.0 MHz 100
LTE Allowed Bandwidths BW (Cont’d)3GPP
The more BW you have o Better throughput o More Resources you have (More Resource block)
# 1
Time Slot0.5 ms
# 2 TS # 20
LTE One Radio Frame 10 ms
One Sub Frame1 ms
1 7
7 Symbols
LTE Frame
Bits Bits Bits Bits Bits BitsBits
64 QAM6 b/s16 QAM
4 b/sQPSK2 b/s
Number of bits per Symbol depend on Modulation technique
# bits = 100 RB * 7 symbols * 12 Subcarrier * 2 (1SB =2RB)*6 bit (64 QAM) * 4 (MIMO)
Throughput RATE = 7 symbols * 12 Subcarrier * 2 (1SB =2RB) *100 * 6 bit (64 QAM) * 4 (MIMO) 1 ms
BW = 20 MHZ
Modulation 64 QAM
MIMO 4*4
Calculate the max. physical throughput in LTE where
BW =20 MHz 100 RB1 RB 7 symbols * 12 Subcarrier
SB = 2 RB (1 ms )
1 Symbol 6 bits (64 QAM)
1 User is scheduled every 1 ms
Throughput RATE = 380 Mbps
LTE Multi Path solution
Channel Paths0
1
23
Path 1
ISI Impact is Very High
Pulse StretchISI Impact is not So High
Lets Remember
CP ASlot A (7 Symbols)
Cyclic Prefix (Inter Symbol interference cure)Slot A (7 Symbols) Slot B (7 Symbols) Slot C (7 Symbols)
Slot A (7 Symbols) Slot B (7 Symbols) Slot C (7 Symbols)
Path 1
Path 2
ISI
Cyclic Prefix Slot T=0
Total Transmitted
Slot A Slot B Slot C
Slot A Slot B Slot C
Path 1
Path 2
CP A
CP A
CP B
CP B
CP C
CP C
ISI
ISI ISI
LTE Radio Channels
LTE Channels
Physical Channel
Transport Channel
LOGICAL CHANNELS
Air Interface
Logical Channels
Transport Channels
Physical channels
LTE Channels
What Type of data I will sentIt may carry control data or carry user traffic
How do I sent the information (the manner in which the data will be Transferred)Weather the data is protected from errors Size of the data packets
Define the way I sent the data What is modulation
What is BW we will use
Logical Channels Transport Channels Physical Channels
BCCHBCH PBCH
MTCH
MCCH PMCHMCH
DTCH
DCCHDL-SCH PDSCH -- Data
PDCCH
PCFICH
PHICH
Broadcast channel
Carry cell information
Multicast channeladvertising
Dedicated Traffic and control
channel“User Data”
Physical downlink control channel
o Scheduler use this channelo Which user will receive datao UE listen to this channel o Ok I have data for me o # of RBso Type of Modulation o Power Control commands
Physical control format indic. channel
o Format of the PDCCH o Data o Power Control
Physical hybrid ARQ indication Ch.
o ACK/NACK
LTE DL Channels
P-SCH
S-SCH
RS
Generated by E-Node-Bused to identify the Cell
LTE UL Channels
Logical ChannelsTransport ChannelsPhysical Channels
PRACHRACH CCCH
Physical Random access channel
Call Setup
PUSCH UL-SCH DTCHPhysical UL
Shared channelData in UL DCCH
PUCCH
Physical UL control channelo Ack/NACK o UL Schedule request
How to identify the enode-B (LTE Cell)
• In 3G we Define the Cell using Scrambling Code (SC)
• In LTE we have Reference Signal (RS) used to define the Cell
• We have 504 different Reference Signals (RS) used to define the Cells
• S-SCH and P-SCH are used to create the (RS)
We have to be synchronized with RS to be able to demodulate the data
P-SCH (3 orthogonal Sequence )
S-SCH (168 Random Sequence)
504 RSs ( 3 orth. * 168 Random )504 PCI
504 Physical Cell Identity
S-SCH (168 Random Seq. )
P-SCH (3 orthogonal Seq.)
S-SCH -0 P-SCH-0 , P-SCH-1 , P-SCH-2S-SCH -1 P-SCH-0 , P-SCH-1 , P-SCH-2S-SCH -3 P-SCH-0 , P-SCH-1 , P-SCH-2S-SCH -4 P-SCH-0 , P-SCH-1 , P-SCH-2
--------------- ---------------------------- -----------
--------------------- ------------------------------ ----------------
------------------------ ------------------------------- ------------
-------------------- ----------------------------- ------------------------------- --------------S-SCH -167 P-SCH-0 , P-SCH-1 , P-SCH-2
• 504 PCI could be reused for LTE network
• PCI Planning Principles
PCI 13PCI 14PCI 12
PCI 15 PCI 18PCI 16
PCI 17
PCI 13
PCI 12
PCI 14
PCI 13PCI 17
PCI 11
PCI 15
PCI 17
PCI 14
PCI 13
PCI 14
PCI 17
PCI 14
PCI 18
PCI 12
PCI 15
PCI 14
PCI 15
Distance between Same PCIWe have 504 so it is easy to avoid this
Same as SC in 3G
Collision Free Confusion Free
Cell 1 Cell 2
PCI -168 PCI 168
PCI -168
PCI 167
PCI -168
Neigh-1 Neigh-2
PCI Planning Principles (Cont’d)
Near Cells should be with different PCI
Synchronized with RS to be able to read the information
Cells in the Neighbor list should be different PCI
# 0 #1
1 Sub Frame1 ms
LTE One Radio Frame 10 ms
0 1 2 3 4 5 6 0 1 2 3 4 5 6
Time Slot 0.5 ms Time Slot 0.5 ms
# 2 # 3 # 4 # 5 # 6 # 7 # 8 # 9
Freq.
Time.
System BW
0 1 2 3 4 5 6 0 1 2 3 4 5 6
Time Slot 0.5 ms Time Slot 0.5 ms
S-SCH P-SCH S-SCH P-SCH
• Information of the Synchronization in Sub frame 0 and 5 (every 5 ms)
P-SCH (3 orthogonal Sequence )
S-SCH (168 Random Sequence)
504 RSs ( 3 orth. * 168 Random )504 PCI
504 Physical Cell Identity
Freq.
Time.
BW U
sed
Cont
ains
Sub
Car
rier
s
• One Resource element : 1 subcarrier and 1 Symbol• One RB : 12 Sub Carrier and 7 Symbol (84 Resource element)
RB
• RS (Reference Signal)
• PDCCH (Schedule use this Ch.)
• PSCH/SSCH • PDSCH (user data)• PBCH
Freq.
Time.
0 1 2 3 4 5 6 0 1 2 3 4 5 6 0 1 2 3 4 5 6
Sub Frame
Time Slot 0.5 ms Time Slot 0.5 ms
• RS (Reference Signal)
• PDCCH (Schedule use this Ch.)• PSCH/SSCH
• PDSCH
• PBCH
10 Sub Frames = 1 Frame (10 ms)
Every time slot we have RS.
We need it in order to decode the information in the slot.
We have to be synchronized with RS to be able to demodulate the data in each slot
Using MIMO
ANTENNA A
ANTENNA B
Freq.
Time.
BW U
sed
Cont
ains
Sub
Car
rier
s
R
R
R
R
R
R
0 1 2 3 4 5 6 0 1 2 3 4 5 6
Sub Frame
Time Slot 0.5 ms Time Slot 0.5 ms
Sub Frame
0 1 2 3 4 5 6 0 1 2 3 4 5 6
Time Slot 0.5 ms Time Slot 0.5 ms
Time.
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
Same Time and Same Sub CarrierSo you will have interference (SINR)You need to Synch. With the RS to read the information in Frame, so if you are not able to get the RS you cant decode any thing
ANTENNA A
ANTENNA B
Freq.
Time.
BW U
sed
Cont
ains
Sub
Car
rier
s
R
R
R
0 1 2 3 4 5 6 0 1 2 3 4 5 6
Sub Frame
Time Slot 0.5 ms Time Slot 0.5 ms
Sub Frame
0 1 2 3 4 5 6 0 1 2 3 4 5 6
Time Slot 0.5 ms Time Slot 0.5 ms
Time.
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
At the same time and Freq. when one antenna transmit RS the other one will not Transmit to avoid interference
So using MIMO you are increasing the throughput but wasting Resource elements
LTE UE Measurements
• What UE measure in the DL ?
• RSRP ( Reference Signal Received Power ) for a certain Cello Measurements of all RS in all BW as average o Ranges -40 to -125 dBm o RSRP is used to measure the coverage
Freq.
Time.
BW U
sed
Cont
ains
Sub
Car
rier
s R
R
R
R
R
R
0 1 2 3 4 5 6 0 1 2 3 4 5 6
Sub Frame
LTE Measurements
• RSSI ( Reference Signal Strength Indicator)o Is the energy in the complete BW o Not the RS only but all the Power and it include the thermal noise alsoo Neighbor Site interference
LTE Measurements
• RSRQ ( Reference Signal Received Quality )o Similar to EcNo in 3G (we use it to measure the interference)o Ranges -3 to -20 dB o RSRQ = n * RSRP (one cell) / RSSI (Power in whole BW for all )
• n is the number of RBs in all the BW
LTE Measurements
• RSRP and RSRQ are used for handovers and cell selection and Reselection• Most operators are now use the RSRP for Mobility instead of RSRQ
o change very Fasto Traffic Dependent due to the RSSIo Its is sense of the cell not the User
RSRQ------
RSRQ lowRSSI High
LTE Measurements• LTE SINR (Signal interference Noise Ratio)
o Is calculated by the UE (no 3GPP but depend on the vendor) S ( Power of the RS and Data) I ( Interference Signals form other cells) N ( back ground noise and Rx Noise coefficient)
SINR
CQI 015
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