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Prof. N P GAJJAR

EC DEPARTMENT

INSTITUTE OF TECHNOLOGY

NIRMA UNIVERSITY

npgajjar@yahoo.com

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History

Introduction to LTE

LTE specification MIMO and different input output schemes

OFDMA and SC-FDMA

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The 0th generation ( 0G).

The first generation (1G) analog systems

The second generation (2G) digitalsystems. The Third generation (3G) systems.

The Fourth generation (4G) systems.

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Mobile radio telephoneTechniques:

PTT : Push To Talk

MTS: Mobile Telephone Services, throughoperator

IMTS improved MTS, no operator

AMTS Advanced Mobile Telephone System.

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Wireless telephone technology

Voice during call was modulated @ 150 MHz

carrier using Analog modulation. Standards

NMT: Nordic Mobile Telephony

AMPS: Advanced Mobile Phone Systems NTT: Nippon Telegraph and Telephone

TACS: Total Access Communication Systems

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Digital encrypting of all telephone calls

Launched SMS data services

for mobile

More efficient

2 techniques:

TDMA and CDMA

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2G systems

GSM CDMA

2G systems wereprimarily designed

To support voice

communication Data transmission

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TDM

CDMA

FDM

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Channel access method for shared medium

networks

TDMA is a type of Time-divisionmultiplexing, with the special point that

instead of having one transmitterconnected to

one receiver, there are multiple transmitters

GSM,PDC and IDEN

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Digital, circuit switching with full

duplex voice telephony 2G

Circuit switched data transport

Improved Packet data transport via GPRS 2.5 G Packet data transport with enhanced speed -2.75

G

TDMA and FDMA GMSK Gaussian minimum-shift keying

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Allows several transmitters to send informationsimultaneously over a single communicationchannel

CDMA is a form ofspread-spectrum signalling,since the modulated coded signal has a muchhigherdata bandwidth than the data being

communicated. Standards:

cdmaOne, cdma 2000 1x ,cdma 2000 3x

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1G

Narrow band analogue Network so only voice calls.

We can contact within premises of nation , No roaming

2G

More clarity to the conversation and can send SMS.

GPRS is not available , No packet data transmission.

In 2.5G packet data service is available but slow datarates.

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The ITU-R initiative on IMT-2000 (international

mobile telecommunications 2000) paved the way for

evolution to 3G.

Requirements

peak data rate of 2 Mb/s and support for vehicular mobility

were published under IMT-2000 initiative.

Both GSM and CDMA standards formed their own

separate 3G partnership projects (3GPP and 3GPP2,

respectively) to develop IMT-2000 compliant

standards based on the CDMA technology.

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GSM 3G (3GPP )- Wideband CDMA(WCDMA) because it uses a larger

5MHz bandwidth.

CDMA ( 3GPP2 )-

CDMA2000 and it uses 1.25MHz bandwidth.

5MHz version supporting three 1.25MHz

subcarriers referred to as cdma2000-3x.

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Problems with 3G

3G standards did not fulfil its promise of high-speed data

transmissions as the data rates supported in practice were

much lower than that claimed in the standards. The 3GPP2 first introduced the HRPD (high rate

packet data) system that supported high speed data

transmission.

HRPD requires a separate 1.25Mhz for data transmissionand no voice service.

So it is referred to as cdma-1x EVDO system.

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The 3GPP introduced HSPA (high speed packetaccess) enhancement to theWCDMA system.

A difference relative to HRPD, however, is that both voice

and data can be carried on the same 5MHz carrier in HSPA.

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WIMAX IEEE 802 LMSC(LAN/MAN Standard Committee)

introduced the IEEE 802.16e standard for mobile

broadband wireless access.

Enhancement to an earlier IEEE 802.16 standard for fixedbroadband wireless access.

Technology - OFDMA (orthogonal frequency division

multiple access)

Better data rates and spectral efficiency than that providedby HSPA and HRPD.

Known as WiMAX (worldwide interoperability for

microwave access) .

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The introduction of Mobile WiMAX led both 3GPP

and 3GPP2 to develop their own version of beyond

3G systems based on the OFDMA technology and

network architecture similar to that in MobileWiMAX.

The beyond 3G system in 3GPP is called evolved

universal terrestrial radio access (evolved UTRA)

and is also widely referred to as LTE (Long-Term

Evolution) while 3GPP2s version is called UMB

(ultra mobile broadband).

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LTE is also known as Long Term Evolution and it is

considered a system beyond existing 3G systems.

The goal of LTE

High-data-rate, low-latency and packet-optimized radio

access technology supporting flexible bandwidth

deployments.

Because of OFDMA and SC-FDMA access

schemes, LTE system supports flexible bandwidth.

In LTE , uplink access is based on SC-FDMA and

downlink access is based on OFDMA.

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LTE supports flexible carrier bandwidths, from

1.4MHz up to 20MHz as well as both FDD

(Frequency Division Duplex) and TDD (Time

Division Duplex).

LTE architecture is referred to as EPS and

comprises the E-UTRAN on the access side andEPC via SAE ,on the core network side.

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FDD

FDD means transmitter and receiver operates atdifferent frequency.

User is able to send and receive data at same time.

Uplink and downlink sub-bands are separated bythefrequency offset.

TDD

It usesT

DM to separate transmitted and receivedsignal.

It has great advantage where there is asymmetrybetween uplink and downlink data rates.

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Increased downlink and uplink peak data rates.

Scalable channel bandwidths of 1.4, 3, 5, 10,

15, and 20 MHz in both the uplink and thedownlink.

Spectral efficiency improvements.

Sub-5 ms latency for small internet protocol(IP) packets.

Optimized Performance.

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SISO

Standard transmission mode.

Single transmitter , single receiver.

SIMO

Single transmitter , multiple receiver.

It aids received data integrity , where signal to

noise ratio is poor due to multipath fading.

MISO

Multiple transmitter , single receiver. The transmitters send the same underlying user

data, but in different parts of the RF frequency

space.

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Multiple transmitter , multiple receiver.

LTE provides multiple access and that is

explained using concept of MIMO.

MIMO is also known as spatialmultiplexing.

MIMO is required to increase high band width

application such as streaming video.

Multiple antennas improve capacity.

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OFDMA

It is FDM used as a digital multi carrier modulationmethod. A large number of closely-spaced orthogonalsub-carriers are used to carry data.

The data is divided into several parallel data channels.Each sub-carrier is modulated with a conventionalmodulation scheme such as QAM or PSK at a lowerrate.

Total data rates similar to single carrier modulationschemes in the same bandwidth.

Due to low symbol rate, guard interval can be providedbetween symbols and hence ISI can be eliminated.

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SC-FDMA

SC-FDMA can be interpreted as a linearly precoded

OFDMA scheme, in the sense that it has an additionalDFT processing preceding the conventional OFDMA

processing.

In SC-FDMA, multiple access among users is made

possible by assigning different users, different sets ofnon-overlapping Fourier-coefficients (sub-carriers).

A prominent advantage of SC-FDMA overOFDMA is

that its transmit signal has a lower peak-to-average

power ratio (PAPR). Due to low PAPR ,it benefits the mobile terminal in

terms of transmit power efficiency.

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In LTE , OFDMA scheme is used for downlinkaccess.

The basic principle of OFDM is to divide the

available spectrum into narrowband parallelchannels referred to as subcarriers and transmitinformation on these parallel channels at areduced signalling rate.

The name OFDM comes from the fact that thefrequency responses of the sub channels areoverlapping and orthogonal.

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The multi-path interference problem ofWCDMA increases for larger bandwidths suchas 10MHz 20MHz required by LTE.

Difficult to employ multiple 5MHz WCDMAcarriers to support 10 and 20MHz bandwidths.

Lack of flexible bandwidth support as

bandwidths supported can only be multiples of5MHz and also bandwidths smaller than5MHz cannot be supported.

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In LTE , SC-FDMA scheme is used for uplink

access.

SC-FDMA enables a lower peak-to-averageratio (PAR) to conserve battery life in mobile

devices.

Single-carrier FDMA scheme provides

orthogonal access to multiple users

simultaneously accessing the system.

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Uplink transmissions should be of low peak

signal due to the limited transmission power at

the user equipment (UE).

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Introduction

LTE Architecture and Network

LTE Radio Interface Architecture and different

parameters

MIMO Spatial Multiplexing

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Things which we have covered in review-1

Basic Introduction of 1G,2G,2.5G,2.75G,3G and

4G.

Introduction of LTE

LTE attributes

LTE uplink and downlink

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The LTE network architecture is

designed with the following goals.

Supporting packet-switched traffic with

seamless mobility

Quality of service(QoS) Minimal latency

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LTE encompasses the evolution of:

The radio access through the E-UTRAN

The non-radio aspects under the term System

Architecture Evolution (SAE)

Entire system composed of both E-UTRAN and

SAE is called the Evolved Packet System (EPS)

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The LTE network is comprised of:

Core Network (CN), called Evolved Packet Core

(EPC) in SAE

Access network (E-UTRAN)

CN is responsible for overall control of UE and

establishment of the bearers.

A bearer is an IP packet flow with a defined QoS(Quality of service) between the gateway and the

User Terminal (UE).

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The LTE network is comprised of:

Core Network (CN), called Evolved Packet Core

(EPC) in SAE

Access network (E-UTRAN)

CN is responsible for overall control of UE and

establishment of the bearers.

A bearer is an IP packet flow with a defined QoS(Quality of service) between the gateway and the

User Terminal (UE).

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Main logical nodes in EPC are:

PDN Gateway (P-GW)

Serving Gateway (S-GW)

Mobility Management Entity (MME) EPC also includes other nodes and functions, such:

Home Subscriber Server (HSS)

Policy Control and Charging Rules Function (PCRF)

E-UTRAN solely contains the evolved base stations,called

eNodeB or eNB

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All the network interfaces are based on IP protocols.

The eNBs are interconnected by means of an X2

interface and to the MME/GW entity by means of an

S1 interface. The S1 interface supports a many-to-many

relationship between MME/GW and eNBs.

The functional split between eNB and MME/GW is

shown in following figure,

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The S-GW acts as a local mobility anchor forwarding

and receiving packets to and from the eNB serving

the UE. The P-GW interfaces with external packet data

networks (PDNs) such as the Internet and the IMS.

The P-GW also performs several IP functions such as

address allocation, packet filtering and routing. The MME is a signaling only entity and hence user IP

packets do not go through MME. An advantage of a

separate network entity for signaling is that the

network capacity for signaling and traffic can grow

independently.

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Radio resource management

IP header compression and encryption

Selection of MME at UE attachment

Routing of user plane data towards S-GW

Scheduling and transmission of paging messages and

broadcast information

Measurement and measurement reportingconfiguration for mobility and scheduling

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Non-access stratum (NAS) signaling and NAS

signaling security

Access stratum (AS) security control

Idle state mobility handling

EPS bearer control

Roaming, authentication

Security negotiations. Authorization and P-GW/S-GW selection

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Mobility anchor point for inter eNB handovers

Termination of user-plane packets for paging reasons

Switching of user plane for UE mobility

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UE IP address allocation

Per-user-based packet filtering

Lawful interception

This was all about functions of different

components in LTE architecture. Now we will see

about LTE Radio Interface and its architecture.

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User plane Protocol

Control plane protocol

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IP packets are passed through multiple protocol entities:

Packet Data Convergence Protocol (PDCP)

IP header compression based on Robust Header

Compression(ROHC) Ciphering and integrity protection of transmitted data

Radio Link Control (RLC)

Segmentation/Concatenation

Retransmission handling

In-sequence delivery to higher layers

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Medium Access Control (MAC)

Handles hybrid-ARQ retransmissions

Uplink and Downlink scheduling at the eNodeB

Physical Layer (PHY)

Coding/Decoding

Modulation/Demodulation (OFDM)

Multi-antenna mapping

Other typical physical layer functions

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RLC offers services to PDCP in the form of radio bearers

MAC offers services to RLC in the form of logical

channels

PHY offers services to MAC in the form of transportchannels

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It includes

Radio Access Modes

Transmission Bandwidth

Supported Frequency Bands

Peak single user data rates and UE

capabilities

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LTE air interface supports

FDD and TDD

Another mode half duplex FDD.

Half-duplex FDD allows the sharing of hardwarebetween the uplink and downlink since the uplink and

downlink are never used simultaneously.

The LTE air interface also supports the multimedia

broadcast and multicast service (MBMS)

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LTE specifications include variable channel

bandwidths selectable from 1.4 to 20 MHz, with

subcarrier spacing of 15 kHz.

A subcarrier spacing of 7.5 kHz is also possible.Subcarrier spacing is constant regardless of the

channel bandwidth.

The smallest amount of resource that can be allocated

in the uplink or downlink is called a resource block(RB). An RB is 180 kHz wide and lasts for one 0.5

ms timeslot. Thus involving FDD as well as TDD.

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The LTE specifications inherit all the frequency

bands defined for UMTS.

FDD spectrum requires pair bands, one of the uplink

and one for the downlink, and TDD requires a single band as uplink and downlink are on the same

frequency but time separated. As a result, there are

different LTE band allocations for TDD and FDD. In

some cases these bands may overlap. Frequency bands for FDD duplex mode and TDD

duplex mode is shown in following figure.

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Mimo spatial multiplexing

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Multiple transmitter , multiple receiver.

As we have seen in the attributes of LTE that LTE

provides multiple access and that is explained using

concept of MIMO. MIMO is also known as spatial multiplexing.

MIMO is required to increase high band width

application such as streaming video.

Multiple antennas improve capacity.

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Spatial multiplexing is a transmission technique

in MIMOWireless Communication.

Purpose: transmit independent and separately encoded

data signals, so-called streams, from each of themultiple transmit antennas.

The space dimension is reused, more than one time.

If the transmitter is equipped with Nt antennas and the

receiver has Nr antennas, the maximum spatialmultiplexing order (the number of streams) is

N(s)=min(Nt, Nr )

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A closed-loop MIMO system utilizes Channel StateInformation (CSI) at the transmitter.

In a closed-loop MIMO system the input-outputrelationship with a closed-loop approach can be described

asy = HWs+n

is Ns x 1 vector of transmittedsymbols .

y,n are the Nr x 1 vectors of received symbols and noise H is the Nr x Nt matrix of channel coefficients

W is the Nt xNs linearprecoding matrix.

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In order that data can be transported across

the LTE radio interface, various "channels"

are used. These are used to segregate the

different types of data and allow them to betransported across the radio access network

in an orderly fashion.

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Physical channels: These are transmission channelsthat carry user data and control messages.

Transport channels: The physical layer transport

channels offer information transfer to Medium Access

Control (MAC) and higher layers.

Logical channels: Provide services for the Medium

Access Control (MAC) layer within the LTE protocol

structure.

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Downlink:

Physical Broadcast Channel (PBCH): This physical channel carries

system information for UEs requiring to access the network.

Physical Control Format Indicator Channel (PCFICH)

Physical Downlink Control Channel (PDCCH) : The main purpose of thisphysical channel is to carry mainly scheduling information.

Physical Hybrid ARQ Indicator Channel (PHICH) : As the name implies,

this channel is used to report the Hybrid ARQ status.

Physical Downlink Shared Channel (PDSCH) : This channel is used for

unicast and paging functions.

Physical Multicast Channel (PMCH) : This physical channel carries

system information for multicast purposes.

Physical Control Format Indicator Channel (PCFICH) : This provides

information to enable the UEs to decode the PDSCH.

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Uplink:

Physical Uplink Control Channel (PUCCH) : Sends

Hybrid ARQ acknowledgement

Physical Uplink Shared Channel (PUSCH) : This physical channel found on the LTE uplink is the

Uplink counterpart of PDSCH

Physical Random Access Channel (PRACH) : This

uplink physical channel is used for random accessfunctions.

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Physical layer transport channels offer information transfer to

medium access control (MAC) and higher layers.

Downlink:

Broadcast Channel (BCH) : The LTE transport channel maps

to Broadcast Control Channel (BCCH)

Downlink Shared Channel (DL-SCH) : This transport

channel is the main channel for downlink data transfer. It is

used by many logical channels.

Paging Channel (PCH) : To convey the PCCH

Multicast Channel (MCH) : This transport channel is used to

transmit MCCH information to set up multicast transmissions.

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Uplink:

Uplink Shared Channel (UL-SCH) : This

transport channel is the main channel for uplink

data transfer. It is used by many logical channels. Random Access Channel (RACH) : This is used

for random access requirements.

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Controlchannels:Broadcast Control Channel (BCCH) : This control channel

provides system information to all mobile terminals connected to theeNodeB.

Paging Control Channel (PCCH) : This control channel is used for

paging information when searching a unit on a network. Common Control Channel (CCCH) : This channel is used for

random access information, e.g. for actions including setting up aconnection.

Multicast Control Channel (MCCH) : This control channel is usedfor Information needed for multicast reception.

Dedicated Control Channel (DCCH) : This control channel is usedfor carrying user-specific control information, e.g. for controllingactions including power control, handover, etc..

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Trafficchannels:

Dedicated Traffic Channel (DTCH) : This traffic

channel is used for the transmission of user data.

Multicast Traffic Channel (MTCH) : This channel isused for the transmission of multicast data.

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LTE for 4G Mobile Broadband by Farooq Khan

LTE-Advanced Signal Generation and Measurement

Using System Vue Application Note By Jinbiao Xu,

Agilent EEsof EDA En.wikipedia.org

Long Term Evolution (LTE) - A Tutorial by Ahmed

Hamza, Network Systems Laboratory, Simon Fraser

University

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Introduction ofWiMAX

Back Ground

HowWIMAX works ?

WIMAX feature

Advantages ofWIMAX

Channel Access

Comparison of LTE andWIMAX

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Emerging technology for broadband wireless access.

Both fixed and mobile broadband wireless Internet

access.

Defines deployment of broadband wirelessmetropolitan area networks.

Promises high data rates and wide coverage at low

cost.

Allows accessing broadband Internet even while

moving at vehicular speeds of up to 125 km/h.

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IEEE 802.16-2004 and IEEE 802.16e-2005 air-

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interface standards.

The WiMAX Forum is developing mobile WiMAX

system profiles that define the mandatory and

optional features of the IEEE standard that are

necessary to build a mobile WiMAX compliant air

interface which can be certified by the WiMAX

Forum.

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Fixed (IEEE 802.16-2004)

Mobile(IEEE 802.16e-2005)

Types ofWIMAX

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It is a non-profit industry body dedicated to

promoting the adoption of this technology and

ensuring that different vendors products will

interoperate. It is doing this through developing conformance and

interoperability test plans and certification program.

WiMAX Forum Certified means a service provider

can buy equipment from more than one company andbe confident that everything works together.

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Channel ( TDM FDM )

Access network

Internet access (Dial-up, DSL and cable modem,BroadbandWireless Access )

point-to-point (PTP) telecommunications

point-to-multipoint (PMP) telecommunications

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WiMAX network consists of

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WiMAX base station

Multiple WiMAX subscriber stations (fixed ormobile).

WiMAX base station is mounted on a tower.

WiMAX subscriber station is a WiMAX customer

premise equipment (CPE) that is located inside thehouse.

WiMAX base station on the tower is physically wired

to the Internet service provider's (ISP) network

through fibre optic cables.

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OFDMA

High Data Rates:

Peak downlink (DL) data rates up to 128 Mbps

Peak uplink (UL) data rates up to 56 Mbps

Quality ofService (QoS):

Fundamental premise of the IEEE 802.16

architecture is QoS.

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Scalability :

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Scalability :

It utilizes scalable OFDMA (SOFDMA) and has

the capability to operate in scalable bandwidthsfrom 1.25 to 20 MHz to comply with various

spectrum allocations worldwide.

Security:

Most advanced security features

Extensible Authentication Protocol (EAP) based

authentication, Advanced Encryption Standard

(AES) based authenticated encryption, and Cipher-based Message Authentication Code (CMAC) and

Hashed Message Authentication Code (HMAC)

based control message protection schemes.

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Uplink and DownlinkTransmissions

Duplexing

TDD and FDD

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Transmission from base station to subscriber stations

is called downlink transmission.

Transmission from subscriber station to base station

is called uplink transmission. Uplink uses Time Division Multiple Access (TDMA).

Downlink uses Time Division Multiplexing (TDM).

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WiMAX provides broadband speeds for voice, data,

and video applications

WiMAX provides wide coverage, high capacity at

low cost WiMAX enjoys a wide industry support

WiMAX being a wireless technology, costs less

because there is no need for service providers to

purchase rights-of-way, dig trenches and lay cables.

WiMAX is standards-based. (IEEE)

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WiMAX can be used for fixed and mobile broadband

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Internet access for data and voice using VoIP (Voice-

over-IP) technology. Because WiMAX is based on wireless technology,

and because it is cost-effective, it is easier to extend

broadband Internet access to suburban and rural

areas. This helps in bringing wireless broadband tothe masses and to bridge the digital divide that exists

especially in developing and underdeveloped

countries.

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According toWiMax Forum it supports 5

classes of applications:

1. Multi-player Interactive Gaming.

2. VOIP and Video Conference

3. Streaming Media

4. Web Browsing and Instant Messaging

5. Media Content Downloads

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Comparison of LTE-WiMAX

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Both LTE and WiMAX both are considered to be

standards for 4G mobile communication.

LTE is the most recent in the line of the GSM

broadband network evolvement. WiMAX evolved from a Wi-Fi, IP-based

background. IEEE standard 802.16.

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1. Both use orthogonal frequency division multiple

access (OFDMA) in the downlink. But WiMax

optimizes for maximum channel usage by processing

all the information in a wide channel. LTE, on theother hand, organizes the available spectrum into

smaller chunks.

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2. LTE uses single-carrier frequency division multiple

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access (SC-FDMA) for uplink signalling, while

W

iMax sticks with OFDMA. A major problem withOFDM-based systems is their high peak-to-average

power ratios. LTE opted for the SC-FDMA

specifically to boost PA efficiency.

3. Although both the IEEE 802.16e standard and theLTE standard support FDD and TDD, WiMax

implementations are predominantly TDD. LTE seems

to be heading in the FDD direction because it is true

full-duplex operation: Adjacent channels are used foruplink and downlink.

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MobileWiMAX

time to market

advantage

IMT-

Advanced

2008 2009 2010 2011 2012

CDMA-Based OFDMA-Based

Mobile WiMAX

Rel1.0802.16e-2005

Rel1.5802.16e Rev 2

Rel2.0802.16m

IP e2e Network

LTE & LTE Advanced

IP e2e Network

3GPP

HSPA+Rel-7 & Rel-8

CktSwitched Network

HSPARel-6

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Parameter LTE Mobile WiMAX Rel 1.5

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Duplex FDD and TDD FDD and TDD

Frequency Band forPerformance Analysis 2000 MHz 2500 MHz

Channel BW Up to 20 MHz Up to 20 MHz

Downlink OFDMA OFDMA

Uplink SC-FDMA OFDMA

DL Spectral Efficiency1 1.57 bps/Hz/Sector

(2x2) MIMO21.59 bps/Hz/Sector

(2x2) MIMO

UL Spectral Efficiency1 0.64 bps/Hz/Sector

(1x2) SIMO20.99 bps/Hz/Sector

(1x2) SIMO

Mobility Support Target: Up to 350 km/hr Up to 120 km/hr

Frame Size 1 millisec 5 millisec

HARQ Incremental Redundancy Chase Combining

Link Budget Typically limited by Mobile Device Typically limited by Mobile Device

Advanced Antenna

Support

DL: 2x2, 2x4, 4x2, 4x4

UL: 1x2, 1x4, 2x2, 2x4

DL: 2x2, 2x4, 4x2, 4x4

UL: 1x2, 1x4, 2x2, 2x4

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Introduction to WiMax and Broadband Access

Technologies By M. Farhad Hussain

WiMAX - An Introduction by N. Srinath (Department

of Computer Science and Engineering, IndianInstitute of Technology Madras)

WiMAX INTRODUCTION by Paul DeBeasi

Introduction to mobile WiMAX Radio Access

Technology by Dr. Sassan Ahmadi (WirelessStandards and Technology, Intel Corporation)

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