LTE Physical Layer

LTE Physical Layer

:Supervised By Prof

AHMED YAHIA04/17/2023

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Prepared by

• Ahmed Abdel-kader Mahmoud• Ahmed Mahmoud Abdel-rahman• Sabry Abdullah Mohamed• Mahmoud Mohsen Mohamed• Hesham Mohamed Refaat• Yaser Mohamd Osman

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Acknowledgement

Any attempt at any level cannot be satisfactorily completed without the will of God and the support and guidance of learned people. We would like to express our immense gratitude to Dr. Ahmed Yahia for his constant support and motivation that has encouraged us to come up with this project.

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CONTENTS Introduction. Mobile Communication Evolution. LTE “Long Term Evolution”. Physical Layer Implementation. VHDL. Simulation. Future work. Conclusion.

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Introduction To Mobile Communication

Cellular concept. Access techniques. Switching techniques. 1st generation. Why 2nd generation ?

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Cellular Concept

• Frequency reuse• Reuse distance• Increasing capacity• Clusters

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Cell TypesCell classifications:

Macro cell……. ( 1 Km: 35km)

Micro cell……..(100m –to- 1Km)

Pico cell…….....(10m)

Umbrella cell….(random)

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Multiple Access TechniquesCDMATDMA

FDMAOFDMA

ff

f

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Switching techniques:

Circuit Switching Packet Switching

Channel for one user Channel for multiple users

One path Multiple path

Fixed bit rate Variable bit rat

Billing by time Billing by volume

Used for real time application Used for data transfer

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1st generation features:

Introduced to commercial uses in early of 1979 & late of 1980

Analog technology

Not compatible system : such as American system (AMPS) uses 800 MHZ and Germany system (c450) used 450 MHZ so no roaming• Access technique (FDMA)• Duplex technique (FDD)

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Mobile Communication Evolutions

GSM

GPRS

EDGEUMTS

LTE

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GSMGlobal System For Mobile Communication

Features. Frequency band. Network architecture.

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Features:

Access techniques:

FDMA / TDMA.FDD.

Operating frequency: (900 –

1800 – 1900) MHz .

8 time slot / carrier.

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Features:

Cellular concept: frequency reuse. Circuit switching.

Data rate: 9.6 Kb/s.

Hard handover

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GSM frequency band:

890 MHz 915 MHz 935MHz 960 MHz

Uplink Guard band Downlink

Channel B.W= 200 KHz

carriers = 25 MHz / 200 KHz = 125 carrier

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GSM Spectrum Allocation :

CH 1 54321 6 70 0 1

Time

CH 3 54321 6 70 0 1

CH 2 54321 6 70 0 1

CH 124 54321 6 70 0 1

Time slot = 0.577 ms Frame duration = 0.577 ms * 8 = 4.616 ms

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Network Architecture GSM

GMSC

MSC

EIR AUC VLR HLR

BSC BSC

Other PLMNs

BTS

BTS

BTS

BTS

IWFSMC

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GPRSGeneral Packet Radio Services:

Features. New services. Network Architecture. Network service area.

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:Features

Various new coding schemes with transmission rates up to 21.4 Kb/s

per physical channel.

Theoretical transmission rate up to

171.2 Kb/s.

Packet & circuit switching.

GPRS enables point-to-point transmission and volume

dependent charging.

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Features

Access techniques :

TDMA/FDMA.

Duplex techniques :

FDD.

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Services offered

“Always on” internet access. Multimedia messaging service (MMS). Internet applications for smart devices through

wireless application protocol (WAP). Point-to-point (PTP) service : inter-networking

with the internet (IP).

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Network Architecture Of GPRS

SGSN

GMSC

MSC

EIR

AUC

VLR

HLR

GGSN

Backbone Network

IP

IPNetwork

BTS/BTS/

BSC/PCU

Other PLMNs

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CDMACode Division Multiple Access

Types Of Spread Spectrum Power Control

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Types Of Spread Spectrum

Direct sequence spread spectrumFrequency hopping spread spectrumTime hopping spread spectrum

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Direct sequence spread spectrum

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UMTSUniversal Mobile Telecommunication System

Features.Frequency band.Network architecture.

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UMTS Features

Wide band CDMA

Frequency band 2100 MHz

Channel bandwidth 5MHz

Chip rate 3.84 Mc/s

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UMTS Features

Channelization codes (4x4 512 x512)

OVSF codes

Rake receiver Soft and softer hand over

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UMTS Features

Inter system hand over

Macro diversity

Variable rate (AMR)

Vo-coder

Closed loop power control

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Network Architecture UMTS

SGSN

GMSC

MSC

EIR

AUC

VLR

HLR

GGSN

IPNetwork

Node BNode BRNC

CGF Billing System

BTSBTSBSC

Node BNode BRNC

GSM BSS

UTRAN Core Network

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Long Term Evolution

LTE Specifications Frequency BandLTE TargetsLTE Network ArchitectureOrthogonal Frequency Division Multiplexing

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LTE Specifications

Digital technology

Cellular concept

OFDMA

Downlink.

SC-FDMA Uplink.

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LTE Specifications

VOIP Technology. Frequency Band 2600MHz

Channel Bandwidth Up To

20MHz

MIMO Technology (2 x 2) or (4 x 4)

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LTE Specifications

Packet Switching.

IP V6

FDD or TDD

New applications

“IP-TV, video streaming, HD

video”

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LTE Frequency Band

• Channel bandwidth 5MHZ to 20 MHZ • Bit Rate 100 Mbps up to 1 Gbps • Sub carrier spacing 15 KHZ

2500MHz 2570MHz 2620MHz 2690MHz

FDD Uplink TDD band FDD Downlink

15 KHZ

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LTE Network Architecture

External networks:Operator services (e.g. IMS) and internet

Services

E-UTRAN

eNode BeNode B

HSSPCRF P-GW

S-GW MMEEPC

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LTE Targets Increasing User Throughput

Increasing Spectral Efficiency

Increasing Number Of Subcarrier15 KHZ

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LTE TargetsDecreasing Latency Factor

MSC

BSC

BTS

MSC

BSC

BTS

MSC

RNC

Node B

MSC

RNC

Node B

S-GW

eNode B

S-GW

eNode B

GSM UMTS LTE

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Basic channel access modesTransmitAntennas

ReceiveAntennas

SISO

The Radio Channel

MISO

Single Input Single Output

Multiple Input Single Output

(Transmit diversity)

ReceiveAntennas

TransmitAntennas

MIMO

The Radio Channel

SIMO

Single Input Multiple Output

(Receive diversity)

Multiple Input Multiple Output(Multiple data streams)

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MIMO

• Transmitting multiple data streams in the same space and time used to be called interference!

• So how does MIMO work?1. MIMO capacity gains come from taking advantage of

spatial diversity in the radio channel

2. The performance can be optimized using precoding

Multiple Input Multiple Output(Multiple data streams)

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OFDMAOrthogonal Frequency Division Multiplexing

OFDM is a spectrally efficient modulation technique ,It is conveniently implemented using IFFT and FFT operations

Bandwidth W being divided into K sub-carriers, leading to carrier spacing Δf, satisfying Δf =W/K

Symbol duration T satisfying T = 1/Δf

SC-FDMA

For the LTE uplink, a different concept is used for the access technique. Although still using a form of OFDMA technology, the implementation is called Single Carrier Frequency Division Multiple Access (SC-FDMA).One of the key parameters that affects all mobiles is that of battery life. Even though battery performance is improving all the time, it is still necessary to ensure that the mobiles use as little battery power as possible

Sc-Fdma

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Multi Path Propgation

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Cyclic prefix insertion

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FAST FOUREER TRANSFORM

• X(m)

• For An 8-point DFT We Would To Have To Perform complex Multiplication i.e. 64 complex Multiplication

• For An 8-point FFT We Would To Have To Perform complex Multiplication i.e. 12 complex Multiplication

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4 minutes

30 seconds

48 seconds

1 second

8 seconds

LTE100

Mbps

HSDPA

WCDMA

EDGE

GPRS

Mobile technology competition

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Data format

CP Insertion

S/P IFFTConvolutional Encoder

Channel interface

Channel

Channelinterface

Interleaver

Channel coding Modules

p/s

s/p

CP REMOVa

FFTp/sViterbiDecoder

DE- Interleaver

Data deformat

OFDM Tx And Rx

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DATA FORMATION

10110100

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Data format

CP Insertion


Channel interface

Channel

Channelinterface

Interleaver


p/s

s/p

CP REMOVa


DE- Interleaver

Data deformat

OFDM Tx And Rx

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Convolutional Encoder

0 0

+

+

Input Output

1

1

c1

c2

1

1 1

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1 0

+

+

Input Output

1

0

c1

c2

0

101 1


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0 1

+

+

Input Output

0

0

c1

c2

1

101 100


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1 0

+

+

Input Output

0

1

c1

c2

1

101 100010


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1 1

+

+

Input Output

1

0

c1

c2

0

101 10001010


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0 1

+

+

Input Output

0

0

c1

c2

1

101 100010100 0


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1 0

+

+

Input Output

1

0

c1

c2

0

101 100010100 001


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0 1

+

+

Input Output

1

1

c1

c2

0

101 100010100 00111000 000000000 00000


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Data format

CP Insertion


Channel interface

Channel

Channelinterface

Interleaver


p/s

s/p

CP REMOVa


DE- Interleaver

Data deformat

OFDM Tx And Rx

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INTERLAEVER

101 1

00

1

10

000

0111

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INTERLAEVER

101 1

00

1

10

000

0111

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OFDM Transmitter

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Data format


Channel interface

Channel

Channelinterface

Interleaver


s/p

CP REMOVa


DE- Interleaver

Data deformat

OFDM Tx And Rx

CP Insertion

S/P IFFT

p/s

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OFDM Transmitter

CP Insertio

n

S/P IFFTS/P

p/s

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Data format

CP Insertion


Channel interface

Channel

Channelinterface

Interleaver


p/s

s/p

CP REMOVa


DE- Interleaver

Data deformat

OFDM Tx And Rx

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OFDM Receiver

CP removals/p

FFT S/P

1

0

1

1

0

01

0

101 10010

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Data format

CP Insertion


Channel interface

Channel

Channelinterface

Interleaver


p/s

s/p

CP REMOVa


DE- Interleaver

Data deformat

OFDM Tx And Rx

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DE-INTERLEAVER

101 1

00

1

10

000

0111

1010

1111

0111

101 0

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Data format

CP Insertion


Channel interface

Channel

Channelinterface

Interleaver


p/s

s/p

CP REMOVa


DE- Interleaver

Data deformat

OFDM Tx And Rx

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VITERBI DECODER

00 00 00

a (00)

b (01)

c (10)

d (11)

11 11 11

01

10 10

10

01 01

11

00

00 00 00 00 00

11 11 11

01 01 01

10 10 10

10 10 10

01 01 01

11 11 11

00 00 00

11

01

10

10

01

11

00

11

01

10

10

01

11

00

11010010100011 01

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Viterbi decoder with error

00 00 00

a (00)

b (01)

c (10)

d (11)

11 11 11

01

10 10

10

01 01

11

00

00 00 00 00 00

11 11 11

01 01 01

10 10 10

10 10 10

01 01 01

11 11 11

00 00 00

11

01

10

10

01

11

00

11

01

10

10

01

11

00

11010110100010 01

1

1

2

2

1

3

2

3

4

1

3

4

3

4

3

4

3

4

4

3

1

5

4

4

4

4

5

1

3

3

5

2

5

2

4

5

6

3

3

5

2

5

2

1 11 10 0 0 0

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Data format

CP Insertion


Channel interface

Channel

Channelinterface

Interleaver


p/s

s/p

CP REMOVa


DE- Interleaver

Data deformat

OFDM Tx And Rx

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DATA DE-FORMATION

1011010000000000

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VHDLVHSIC Hardware

Description Language

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VHDL’s Organization

• The basic VHDL model is known as a Design Entity and has two parts• Interface - denoted by keyword entity • defines I/O signals for the model

• Body - denoted by keyword architecture• describes how the model works

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VHDL (Xor) Exampleentity XOR2_OP is -- Input/Output ports port (A, B : in BIT; Z : out BIT);end XOR2_OP;

architecture EXD of XOR2_OP is -- declarations go before beginbegin Z <= A xor B;end EXD

Interface

Body

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Interleaver code

entity interleaver is

Port ( clk : in STD_LOGIC;

rst : in STD_LOGIC;

input : in STD_LOGIC;

output : out STD_LOGIC);

end inter;

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Architecture partarchitecture Behavioral of interleaver is

signal temp1 : std_logic_vector (3 downto 0);




signal x1 : std_logic_vector (3 downto 0);



signal x4 :std_logic_vector (3 downto 0);

signal y : std_logic_vector (15 downto 0);

signal count1 : std_logic_vector (4 downto 0);

signal count2 : std_logic_vector (4 downto 0);

temp1

temp2

temp3

temp4

x1 x2 x3 x4

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Architecture part

begin

process (clk,rst,input)

begin

if rst = '1' then

output <= '0';

count1 <= "00000";

count2 <= "00000";

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Architecture partelsif rising_edge (clk) then

if count1 < "10001" then

temp1 <= input & temp1 (3 downto 1);

temp2 <= temp1(0) & temp2 (3 downto 1);



x1 <= temp1(0) & temp2(0) & temp3(0) & temp4(0);




count1 <= count1 + 1 ;

end if;

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Architecture partif count1 = "10001" then

y <= x1 & x2 & x3 & x4 ;

count1 <= "00000";

end if;

if count2 < "10001" then

output <= y(0);

y <= '0' & y (15 downto 1);

count2 <= count2 + 1 ;

else

count2 <= "00000";

end if;

end if;

end process;

end Behavioral;

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•Data Format block behave as parallel in serial out (PISO) register which converts the input with parallel form to the output with serial form.• It adds tail of Zeros to the input data.• It generates the required signals for convolutional encoder.

Data formation PISO

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Data formation

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Parallel to serial module

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Convolutional encoder• We have used R = ½ , K=3.• It is used to encode each 1 bit into 2 bits for error detection

and correction purposes.

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Convolutional encoder simulation

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InterleaverRandomizes The Sequence of Data By Storing It Row by Row & Retrieving It Column by Column For Error Isolation

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Interleaver Simulation

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Data deformation SIPO

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serial to Parallel module

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Data de-formation

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FPGA

• Xilinx XC3S500E Spartan-3E FPGA• • Up to 232 user-I/O pins• • Over 10,000 logic cells• 2-line,16-character LCD screen• 50MHz clock oscillator

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Future work Suggestions

Channel Estimation Improvement

The next step in improvement would be use a channel estimator that utilizes channel statistics,which known as minimum mean-squared error estimation (MMSE).

Developing other modules

For the future works, it is suggested to develop other modules such as advanced error correction teqniques, QAM or QPSK modulation RF part. These modules will make a complete set of OFDM system for transmitter and receiver.

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Conculosion• Presenting the way for people in the past to communicate• Presenting the creation of mobile phone starting from the 2nd Generation which

is called Global system for mobile communication (GSM)• The progresses that happened to make it better by using the General Packet

Radio Service (GPRS).• Presenting the birth of the 3rd Generation that enables all subscribers to send

and receive lager amount of data than GSM including pictures, faxes, e-mails and internet browsing.

• The real revolution of mobile communications occurs by the invention of the CDMA in USA and the Universal Mobile Telecommunication System (UMTS) in Europe.

• Enabling all subscribers to hold video calls and support them by offering larger capacity for data rate and multimedia messages.

• Finally, Presenting the 4th generation including LTE, and UMB increases the transmission rate with much higher quality.

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Thanks all

To Parctical Part….

Documents

LTE Physical Layer