wireless roadmap & lte

8/12/2019 Wireless Roadmap & LTE

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Wireless Broadband Roadmap&

LTE Technology



Module 1 – WCDMA Fundamentals

ObjectivesAfter this module the participant shall be able to:-

Understand the user requirement from a network andreason of 3G Failure.

Targets and market scenario of LTE Technology. Features and services of LTE.

LTE network architecture evolution.

Air Interface.

Logical, Transport and Physical Channel. OFDMA and SCFDMA.



User Expectations

• Highly desire of broadband acces everywhere

1. Home, Office

2. Train, Aeroplane, Canteen, during the Breake

• Ubiquity (anywhere, anytime, wire free broadband)

• Higher voice quality

• Higher speed

• Lower prices

• Multitude of services



Key considerations for the evolved packet network

• Integration of intelligence at the access edge.

• Simplified network topology.

• Optimized backhaul.

• Converged mobility and policy.

• Increased performance characteristics.

• 2G/3G to 4G migration.



HSPA Limitations

• The maximum bit rates still are factor of 20 and more behind the current state

of the art systems like 802.11n and 802.16e/m. Even the support for highermobility levels is not an excuse for this.

• The latency of user plane traffic (UMTS: >30ms) and of resource assignment

procedures (UMTS: >100ms) is too big to handle traffic with high bit rate

variance efficiently.

• The terminal complexity for WCDMA or MC-CDMA systems is quite high,making equipment expensive, resulting in poor performing implementations

of receivers and inhibiting the implementation of other performance

enhancements.

• Cell Breathing: The cell coverage shrinks as the loading increases



Comparisons Between 3G & 4G



LTE Targets

• Spectral efficiency two to four times more

than with HSPA Release 6;• Peak rates exceed 100 Mbps in downlink

and 50 Mbps in uplink;

• Enables round trip time <10ms;

• Packet switched optimized;

• High level of mobility and security;

• Optimized terminal power efficiency;• Frequency flexibility with from below 1.5

MHz up to 20 MHz allocations.



LTE Roadmap:- 1/2

Global market share of 3GPP and 3GPP2 technologies. EVDO, evolution data only.



• Schedule of 3GPP standard and their commercial deployments.

• Peak data rate evolution of 3GPP technologies

LTE Roadmap:- 2/2



Traffic forecast



LTE Market Scenario



LTE Market Scenario

Evolution to LTE report, revealing that there

are now 218 operators investing in LTE

worldwide, with 91 commercial roll-outs

expected by 2012. This number consists of

166 firm commercial deployments either in

progress or planned across 62 countries and

52 operators in 19 countries that areengaged in trials.



LTE Positioning & Technology



LTE specification work



LTE Features

A complete move to packet-basedprocessing.

Support scalable bandwidths of 1.4, 3, 5.0,

10.0 and 20.0MHz.

Supported antenna configurations.• Downlink: 4 x 4, 4 x 2, 2 x 2, 1 x 2, 1 x 1.

• Uplink: 1 x 1, 2, 4.

Spectrum efficiency.• Downlink: 3 to 4 x HSDPA.

• Uplink: 2 to 3 x HSUPA.

Latency.• Control plane: less than 50 to 100msec to

establish user.

• User plane: less than 5msec from userterminal (UE) to server, on IP layer.



Mobility

• Optimized for low speeds up to 15kmph.

• High performance at speeds up to 120kmph.

• Maintain link at speeds up to 350kmph.

Coverage

• Full performance up to 5 km.

• Slight degradation 5 km to 30 km.• Operation up to 100 km should not be precluded by standard

MIMO• Multiple Input Multiple Output• LTE will support MIMO as an option,• It describes the possibility to have multiple transmitter and

receiver antennas in a system.• Up to four antennas can be used by a single LTE cell (gain: spatial

multiplexing)• MIMO is considered to be the core technology to increase spectral

efficiency.

LTE Features (Count.)



Available LTE Spectrum



E-UTRA Band Uplink Downlink Uplink-Downlink Separation Duplex Mode

1 1920 – 1980 MHz 2110 – 2170 MHz 130 MHz FDD

2 1850 – 1910 MHz 1930 – 1990 MHz 20 MHz FDD

3 1710 – 1785 MHz 1805 – 1880 MHz 20 MHz FDD

4 1710 – 1755 MHz 2110 – 2155 MHz 355 MHz FDD

5 824 – 849 MHz 869 – 894 MHz 20 MHz FDD

6 830 – 840 MHz 875 – 885 MHz 35 MHz FDD

7 2500 – 2570 MHz 2620 – 2690 MHz 50 MHz FDD

8 880 – 915 MHz 925 – 960 MHz 10 MHz FDD

9 1749.9 – 1784.9 MHz 1844.9 – 1879.9 MHz 60 MHz FDD

10 1710 – 1770 MHz 2110 – 2170 MHz 340 MHz FDD

11 1427.9 – 1452.9 MHz 1475.9 – 1500.9 MHz 23 MHz FDD

…

13 777 - 787 MHz 746 - 756 MHz 21 MHz FDD

14 788 - 798 MHz 758 - 768 MHz 20 MHz FDD

…

33 1900 –

1920 MHz 1900 –

1920 MHz N/A TDD

34 2010 – 2025 MHz 2010 – 2025 MHz N/A TDD

35 1850 – 1910 MHz 1850 – 1910 MHz N/A TDD

36 1930 – 1990 MHz 1930 – 1990 MHz N/A TDD

37 1910 – 1930 MHz 1910 – 1930 MHz N/A TDD

38 2570 – 2620 MHz 2570 – 2620 MHz N/A TDD

39 1880 – 1920 MHz 1880 – 1920 MHz N/A TDD

40 2300 – 2400 MHz 2300 – 2400 MHz N/A TDD

Available Frequency Band List of LTE



LTE FDD and TDD Modes



LTE Architecture

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 LTE and SAE is called the

Evolved Packet System (EPS)

At a high-level, the network is comprised of:

Core Network (CN), called Evolved Packet Core (EPC) in SAE access network (E-UTRAN)

A bearer is an IP packet flow with a defined QoS between the gateway and the User

Terminal (UE) CN is responsible for overall control of UE and establishment of the bearers.



LTE System Architecture Evolution



LTE Architecture [EPS]

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)

EPS only provides a bearer path of a certain QoS, control of multimedia applications isprovided by the IP Multimedia Subsystem (IMS), which considered outside of EPS

E-UTRAN solely contains the evolved base stations, called eNodeB or eNB



Evolved Packet System (EPS) Architecture – Subsystems



System Architecture Evolution(SAE)

System Architecture Evolution (aka SAE) is the core network architecture of 3GPP's future

LTE wireless communication standard. SAE is the evolution of the GPRS Core Network, with some differences.

The main principles and objectives of the LTE-SAE architecture include :

• A common anchor point and gateway (GW) node for all access technologies

• IP-based protocols on all interfaces;

• Simplified network architecture• All IP network

• All services are via Packet Switched domain

• Support mobility between heterogeneous RATs, including legacy systems as GPRS,

but also non-3GPP systems (say WiMAX)

• Support for multiple, heterogeneous RATs, including legacy systems as GPRS, but

also non-3GPP systems (say WiMAX)



[Source:http://www.3gpp.org/Highlights/LTE/LTE.htm]

System Architecture Evolution (SAE)



LTE Frame Structure

• One element that is shared by the LTE Downlink and Uplink is the generic frame

structure. The LTE specifications define both FDD and TDD modes of operation. This

generic frame structure is used with FDD. Alternative frame structures are defined for

use with TDD.

[source: 3GPP TR 25.814]

• LTE frames are 10 msec in duration. They are divided into 10 subframes, eachsubframe being 1.0 msec long. Each subframe is further divided into two slots, each

of 0.5 msec duration. Slots consist of either 6 or 7 ODFM symbols, depending on

whether the normal or extended cyclic prefix is employed



Generic Frame structure

Available Downlink Bandwidth is Divided into Physical Resource Blocks

[source: 3GPP TR 25.814]

LTE Reference Signals

are Interspersed Among

Resource Elements



Protocol Layers

IP packets are passed through multiple protocol entities:

• Packet Data Convergence Protocol (PDCP)

• Radio Link Control (RLC)• Medium Access Control (MAC)

• Physical Layer (PHY)

Communication Channels

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 transport channels

A logical channel is defined by the type of information it carries. Generally

classified as:

• a control channel, used for transmission of control and configuration

information necessary for operating an LTE system

• a traffic channel, used for the user data

A transport channel is defined by how and with what characteristics the

information is transmitted over the radio interface



Channels

Logical channels

Logical channels can be classified incontrol and traffic channels.

• Control channels are:

Broadcast Control Channel (BCCH)

Paging Control Channel (PCCH)

Common Control Channel (CCCH)

Multicast Control Channel (MCCH)

Dedicated Control Channel (DCCH)

• Traffic channels are:

Dedicated Traffic Channel (DTCH)

Multicast Traffic Channel (MTCH)

Mapping between downlink logical and transport channels

Mapping between uplink logical and transport channels



Transport channels

In order to reduce complexity of the LTE protocol architecture, the number oftransport channels has been reduced. This is mainly due to the focus on

shared channel operation, i.e. no dedicated channels are used any more.

• Downlink transport channels are

Broadcast Channel (BCH)

Downlink Shared Channel (DL-SCH)

Paging Channel (PCH)

Multicast Channel (MCH)

• Uplink transport channels are:

Uplink Shared Channel (UL-SCH)Random Access Channel (RACH)

Channels



Physical channels

• Downlink: – Physical Downlink Shared Channel (PDSCH),

– Physical Multicast Channel (PMCH),

– Physical Downlink Control Channel (PDCCH),

– Physical Broadcast Channel (PBCH),

– Physical Control Format Indicator Channel (PCFICH),

– Physical Hybrid ARQ Indicator Channel (PHICH).

• Uplink:

– Physical Uplink Shared Channel (PUSCH),

– Physical Uplink Control Channel (PUCCH),

– Physical Random Access Channel (PRACH).

• Additional, signals: (i) reference signals, (ii) primary and (iii) secondary

synchronization signals.

• The modulation schemes supported in the downlink and uplink are QPSK, 16QAM

and 64QAM.

Channels



Channel Mapping



Multiple Access Technologies

OFDM/OFDMA/SC‐FDMA



Multiple Access

OFDMA

• Downlink multiplexing

• OFDMA stands for Orthogonal Frequency Division Multiple Access

• Receiver complexity is at a reasonable level

• Improved spectral efficiency

• Reduced interference

• Very well suited for MIMO

SC-FDMA

• Uplink multiplexing

• SC-FDMA stands for Single Carrier Frequency Division Multiple Access, a variant of

OFDMA

• The advantage against OFDMA is to have a lower PAPR (Peak-to-Average PowerRatio) meaning less power consumption and less expensive RF amplifiers in the

terminal.

• Power efficient uplink increasing battery lifetime

• Reduced Terminal complexity



Pulse shaping and Spectrum

• Two characteristics are important for a Signal:

- The time domain presentation:

It helps recognize “how long the symbol lasts on air”

- The frequency domain presentation:

to understand the required spectrum in terms of

bandwidth

• It is one of the most simple time‐domain pulses.

• It simply jumps at time t=0 to its maximum

amplitude and after the pulse duration Ts just goes

back to 0.



OFDM: Orthogonal Frequency DivisionMulti‐Carrier

• For the rectangular pulse there is a better

option possible and it is even easier toimplement.

• We must just notice that the spectrum of a

rectangular pulses shows null points exactly

at integer multiples of the frequency given

by the symbol duration.

• The only exception is the center frequency(peak power)

Spectrum Overlapping of multiple OFDM

carriers



OFDM: Orthogonal Frequency Division

Multi‐Carrier



OFDM Transmitter

OFDM Receiver



Solution to ISI: Cyclic Prefix



Cyclic Prefix



OFDM Key Parameters

2. Subcarrier Spacing (Δf = 15 KHz)→ The Symbol time is

Tsymbol = 1/ Δf = 66,7μs

Δf

A compromise needed between:

→ Δf as small as possible so that the

symbol time Tsymbol is as large as

possibile.

This is beneficial to solve Intersymbol

Interference in time domain

→ A too small subcarrier spacing it is

increasing the ICI = Intercarrier

Interference due to Doppler effect

TSYMBOL

TCP SYMBOL

TCP

TS

Frequency

Time

Powerdensity

Amplitude

1. Variable Bandwidth (BW)

Frequency

A higher Bandwidth is betterbecause a higher peak data rate

could be achived and also bigger

capacity. Also the physical layer

overhead is lower for higher

bandwidth

Bandwidth options: 1.4, 3, 5, 10, 15 and 20 MHz



3. The number of Subcarriers Nc

→ Nc x Δf = BW

In LTE not all the available channel bandwidth (e.g. 20 MHz) will be used. For the

transmission bandwidth typically 10% guard band is considered (to avoid the out band

emissions).

If BW = 20MHz → Transmission BW = 20MHz – 2MHz = 18 MHz

→ the number of subcarriers Nc = 18MHz/15KHz = 1200 subcarriers

TransmissionBandwidth [RB]

Transmission Bandwidth Configuration [RB]

Channel Bandwidth [MHz]

R

e s o u r c e

b l o c k

C h a n n e

l e d g e

C h a n n e

l e d g e

DC carrier (downlink only)Active Resource Blocks

OFDM Key Parameters



4. FFT (Fast Fourier Transform) size Nfft

Nfft should be chosen so that:

1. Nfft > Nc number of subcarriers (sampling theorem)

2. Should be a power of 2 (to speed-up the FFT operation)

Therefore for a bandwidth BW = 20 MHz → Nc = 1200 subcarriers not a power of 2

→ The next power of 2 is 2048 → the rest 2048 -1200 = 848 padded with zeros

5. Sampling rate fsThis parameter indicates what is the sampling frequency:

→ fs = Nfft x Δf

Example: for a bandwidth BW = 5 MHz (with 10% guard band)

The number of subcarriers Nc = 4.5 MHz/ 15 KHz = 300

300 is not a power of 2 → next power of 2 is 512 → Nfft = 512

Fs = 512 x 15 KHz = 7,68 MHz → fs = 2 x 3,84 MHz which is the chip rate in UMTS!!

The sampling rate is a multiple of the chip rate

from UMTS/ HSPA. This was acomplished because the

subcarriers spacing is 15 KHz. This means UMTS and LTE

have the same clock timing!

OFDM Key Parameters



OFDM Key Parameters for FDD and TDD Modes

Bandwidth

(NC×Δf)1.4 MH 3 MHz 5 MHz 10 MHz 15 MHz 20 MHz

Subcarrier Fixed to 15 kHz (7.5kHz defined for MBMS)Spacing (Δf)

Symbol Tsymbol = 1/Δf = 1/15kHz = 66.67μs

duration

Sampling rate,

f S (MHz)

1.92 3.84 7.68 15.36 23.04 30.72

Data

Subcarriers (NC) 72 180 300 600 900 1200

NIFFT

(IFFT Length) 128 320 512 1024 1536 2048

Number ofResource Blocks 6 15 25 50 75 100

Symbols/slot Normal CP=7; extended CP=6

CP length Normal CP=4.69/5.12μsec., Extended CP= 16.67μsec



SC-FDMA



SC-FDMA Basic Concept



OFDMA and SC-FDMA Tx/Rx: Summary



Comparing OFDMA & SC‐FDMA



LTE becomes LTE-Advanced with 3GPP Rel10

LTE-A fulfills or exceeds therequirements ofIMT-Advanced defined by ITU

Data rates

Mobility

LTE-Advanced Goals

Enhance macro network performance

Enable efficient use of small cells

More Bandwidth available

Able to achieve higher data rates ( upto 1Gbps in downlink for stationary

users)

Enhance the coverage by increasingdata rates on the cell edge

Meet and exceed capabilities

requested for IMT-Advanced

Backward compatibility

Meet 3GPP operators’ requirements

for LTE evolution



LTE-A Peak Data Rates with MIMO ExtensionAssuming 2x20 MHz Carrier Aggregation

eNBantennas

UEantennas

1 2 4 8

1

2

4

8 1102

555

304

161

610

305

152

The 500 Mbps targetfor uplink is

exceeded with 4x4and 40 MHzbandwidth

1 Gbps target for DLis exceeded with 8x8

and 40 MHzbandwidth

The larger data ratefor UL is due to less

overhead

Downlink [Mbps] Uplink [Mbps]

64QAM with maximumeffective code rate of9/10 is assumed forboth uplink anddownlink.

Data rate scaleslinearly with number of

component carriers.



LTE-Advanced:First features standardized in 3GPP Release10

Key aspects in

3GPP Rel.10

• Carrier Bandwidth extension by carrier aggregation

• Downlink: Up to 100 MHz bandwidth with 2 Release 8carriers from different frequency bands

• Uplink: Only single band carrier aggregation

• New codebook for downlink (DL) 8TX MIMO

• Feedback enhancements for DL 2TX/4TX Multiuser MIMO

• 2TX/4TX Uplink Single/Multiuser MIMO

• Single Relay Node architecture based on self-backhauling eNB

• Simple intercell interference coordination in time domain

• Enhancements for office Femto handovers

Heterogeneousnetworks

MIMO 4x8x

Coordinated Multipoint

Relaying

Carrier Aggregation

Carrier1 Carrier nCarrier2

…..

• Coordinated multipoint transmission (CoMP), alsoknown as cooperative system

• Receiving transmission from multiple sectors (not

necessary visible for UE)



Carrier Aggregation

Mobility

in June 2009

Component Carrier

(LTE rel. 8 Carrier)

Aggregated BW: 30MHz

Aggregated BW: 5x20MHz = 100MHz

20 MHz

300Mbps 300Mbps 300Mbps 300Mbps300Mbps

1.5Gbps

• Up to 100 MHz

• Flexible component carrier aggregation• Different frequency bands

• Asymmetric in UL/DL

10 MHz20 MHz

20 MHz 20 MHz20 MHz20 MHz



MIMO



Coordinate Multipoint

Service Area

Relaying

• Cooperation of antennas of multiple sectors

/ sites

• Interference free by coordinated

transmission / reception

• Highest performance potential

• Fast deployment• Coverage with low infrastructure costs



Heterogeneous Networks

Heterogeneous Networks –

TheCombined Benefit of Wide & Local Area

Wide Area sites

Medium

area sites

Local

area

Local

area

Local

area

Local

area

WLAN

WLANWLAN

Medium

area sites

Local

area

WLAN

WLAN



LTE- Advance Summary

Beyond 3GPP Rel 10

• Flexible Spectrum Use

• New Spectral Territory

• D2D communication

• …

Technology Building Blocks

• Cooperative Transmission

• Relaying• Enhanced MIMO, Beamforming

• Carrier Aggregation

3GPP Standardization

• Starting with Release 10

• Study Item in final phase

• ITU-R submission

• LTE-A meets all requirements

Operator Benefits

• Full backwards compatibility

• Future proof long term

evolution

• extreme efficiency

Timing

• 2010 LTE 3GPP R9 gets ready

• 2011 ITU will select RITs

• 2011 R10 gets cast in stone

• 2014+ 1st networks with LTE-A

Requirements

• Exceeds all ITU-R requirements

and meets time line

• Fulfilling 3GPP requirements

• Smooth evolution path from

LTE

Self OrganizingNetworks

• Auto-Configuration

• Auto-Tuning

• Auto-Repair



TH NK YOU

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