lte vs. 3g

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


b

Freq.

Time

Time Slot7 Symbols

0.5 ms

12 Sub Carrier

Symbol

One Recourse block84 Recourse element


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


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


• 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


Sub Frame

0 1 2 3 4 5 6 0 1 2 3 4 5 6


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


Sub Frame

0 1 2 3 4 5 6 0 1 2 3 4 5 6


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

سلطانه وعظيم وجهه لجالل ينبغي كما لله الحمدشكرا

lte vs. 3g

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