3. Agenda
LTE 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
5. 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.
Core
Signaling 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
7. HSPDA HSPDA
DC
HSPDA
MIMO
LTE
2*2 MIMO
LTE advance
Throughput
21 Mbps
42 Mbps
84 Mbps
150 Mbps
3 Gbps
LTE
4 * 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
8. User Data
2 3 5 6 7 841
Bad CQI
Good CQI
Low data rate
TX Diversity
10 11 13 14 15129
2 3 5 6 7 841
3 5 6 7 841 2 16
A
N
T
E
N
N
A
A
A
N
T
E
N
N
A
B
High data rate
No TX Diversity
MULTIPLE INPUT MULTIPLE OUTPUT (MIMO)
9. SF 8
(480 KSps)
SF 2
(1.92 MSps)
SF 1 (3.84 MSps)
SF 4
(960 KSps)
How to calculate the HS Throughput
3G Code Tree
SF 16
(240 KSps)
HSDPA Works on SF 16
10. How to calculate the HS Throughput
64 QAM
6 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
11. SF 8
480 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)
12. 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
14. 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
15. X2
eNB 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 Forwarding
Charging
• Service Gateway
Limit throughput for certain application
during hours
IP address allocation
Deep packet inspection (Forbid application)
Keep packet and Drop packets
Prevent SKYPE , Torrent
Specific Charging for this certain packet
• Packet GateWay
16. BTS
BSC
NodeB NodeB
RNC RNC
eNB eNB
SP-
GW
SGSN
GGSN
MME
S11
X2 UP
S1 CP
S1 UP
S3
MME
S10
Not 3GPP Wifi
S2
IUR
S4 UP
Abis
Gb
Gn
S4 CP
IUB
IU
X2 CP
Internet
2G 3G LTE
S4 UP
18. LTE Key Performance
Higher Order Modulation
64 QAM
16 QAM
QPSK
1.4 MHz 3 MHz 5 MHz 15 MHz 20 MHz
Scalable BW
Flat IP Arch.
T
X
R
X
F0 F2 F3 FrequencyF1
MME
New Air Interface Access Tech.
MIMO
22. 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
23. 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 F4
Frequency
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
24. F1 F3 F4F2 F5 F7 F8F6
Time
Freq.
Sub Carrier BW = 15 KHz
Symbol
LTE Access Technique (OFDM)
25. LTE Downlink DL
Time
Freq.
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).
26. LTE Radio access Uplink UL
Single Carrier
Single
Carrier
Single Carrier
LTE use OFDM in UL (Single Carrier OFDM)
Subcarrier BM is 15 KHz
27. Why SC Carrier in UL
o To avoid Peak to Average Power Ratio PAPR
o Any PA should be operated in the linear region other wise you will have
distortion in the O/P signal
Linear Region
29. 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
FFT
Single Carrier
For UL Convert Subcarriers to Single Carrier (to Avoid PAPR)
32. LTE Radio Physical Resource
Resource Element (RE)
Freq.
Time
LTE Time Slot
0.5 ms
7 Symbols
1 Sub Carrier( 15 kHz)
LTE Symbol (Contain # of bits)
Depend on Modulation
1 Recourse Element
1 subcarrier and 1 Symbol
33. LTE Radio Physical Resource
Resource Block (RB)
Freq.
Time
LTE Time Slot
0.5 ms
7 Symbol
1 Recourse block ( RB )
o 12 Sub Carrier (15 KHz) * 7 Symbols
o 84 Recourse Element
o RB Basic Unit for Transmission of information
12 Sub Carrier
34. LTE Radio Physical Resource
Resource Block (RB)
Freq.
Time
Time Slot
7 Symbols
0.5 ms
12 Sub Carrier
Symbol
One Recourse block
84 Recourse element
35. LTE Radio Physical Resource
Resource Block (RB)
Freq.
Time
Time Slot
7 Symbols
0.5 ms
12 Sub Carrier
Symbol
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
36. Freq.
Time
Time Slot
7 Symbols
0.5 ms
Time Slot
7 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
37. 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
38. Band Width MHz Number of RB s
1.4 MHz 6
3.0 MHz 15
5.0 MHz 25
10.0 MHz 50
15.0 MHz 75
20.0 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)
39. # 1
Time Slot
0.5 ms
# 2 TS # 20
LTE One Radio Frame 10 ms
One Sub Frame
1 ms
1 7
7 Symbols
LTE Frame
Bits Bits Bits Bits Bits BitsBits
64 QAM
6 b/s
16 QAM
4 b/s
QPSK
2 b/s
Number of bits per Symbol depend on Modulation technique
40. # 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 RB
1 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
43. CP A
Slot 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
46. Logical Channels
Transport Channels
Physical channels
LTE Channels
What Type of data I will sent
It 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
47. Logical Channels Transport Channels Physical Channels
BCCH
BCH
PBCH
MTCH
MCCH
PMCH
MCH
DTCH
DCCH
DL-SCH PDSCH -- Data
PDCCH
PCFICH
PHICH
Broadcast channel
Carry cell
information
Multicast channel
advertising
Dedicated Traffic
and control channel
“User Data”
Physical downlink control channel
o Scheduler use this channel
o Which user will receive data
o UE listen to this channel
o Ok I have data for me
o # of RBs
o 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-B
used to identify the Cell
48. LTE UL Channels
Logical ChannelsTransport ChannelsPhysical Channels
PRACH
RACH
CCCH
Physical Random
access channel
Call Setup
PUSCH UL-SCH
DTCH
Physical UL Shared
channel
Data in UL
DCCH
PUCCH
Physical UL control channel
o Ack/NACK
o UL Schedule request
49. 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
51. • PCI Planning Principles
PCI 13
PCI 14PCI 12
PCI 15 PCI 18
PCI 16
PCI 17
PCI 13
PCI 12
PCI 14
PCI 13
PCI 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 PCI
We have 504 so it is easy to avoid this
Same as SC in 3G
52. 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
53. # 0 #1
1 Sub Frame
1 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.
SystemBW
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
54. Freq.
Time.
BWUsed
ContainsSubCarriers
• 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
55. • 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
57. A
N
T
E
N
N
A
A
A
N
T
E
N
N
A
B
Freq.
Time.
BWUsed
ContainsSubCarriers
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 Carrier
So 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
58. A
N
T
E
N
N
A
A
A
N
T
E
N
N
A
B
Freq.
Time.
BWUsed
ContainsSubCarriers
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
60. • RSRP ( Reference Signal Received Power ) for a certain Cell
o 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.
BWUsedContainsSubCarriers
R
R
R
R
R
R
0 1 2 3 4 5 6 0 1 2 3 4 5 6
Sub Frame
LTE Measurements
61. • 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 also
o Neighbor Site interference
LTE Measurements
62. • 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 Fast
o Traffic Dependent due to the RSSI
o Its is sense of the cell not the User
RSRQ
-
-
-
-
-
-
RSRQ low
RSSI High
63. 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
PDCCH:
Physical downlink control channel
Scheduler use this channel
Which user will receive data
UE listen to this channel
Ok I have data for me
# of RBs
Type of Modulation
Power Control commands
PDCCH:
Physical downlink control channel
Scheduler use this channel
Which user will receive data
UE listen to this channel
Ok I have data for me
# of RBs
Type of Modulation
Power Control commands
