Mobility Management Challenges and Mobility Management Challenges and Issues in 4G Heterogeneous NetworksIssues in 4G Heterogeneous Networks

By By AJAL.A.JAJAL.A.J

Towards 4GTowards 4GUser centric, user controlled services

andcontext-aware applications

Technologies

ChallengesChallenges

• Convergence/integration/inter-working of all existing and emerging fixed and mobile (wired and wireless) networks including broadcast

• Simple to select and easy to use desired services

• Universal and low cost terminals

IP Technology

Agent Technology

Reconfigurable Technology

The Internet

IP backbone

BillingVHE

Signalling Gateway

WAP Accounting

UMTS

Broadcast Networks (DAB, DVB-T)

Satellite FES

GSM / GPRS

Context-aware informationCentre

IP-based micro-mobility Wireless

LANs

ISPSIP Proxy Server

Inter-Working

Global coverage

National coverage

Local area coverageWireless LANs

DAB and DVB-T, DVB-S

2G, 3G and 4G Cellular

Personal area coverage

Hierarchical coverage layers for 4G

Satellite

Regional coverage

Wireless PANs

Vertical Handover

Horizontal Handover

IP-based backbone

Multi-Agency Seamless Mobility

The Future Home…

DSL/Cable or MSOTelephone

Wireless camera

Wireless media

gateway

NAS for MP3 & Video

Content

Integrated networks, content,and entertainment systems

Managed Security

Managed Voice

Managed Wireless

Success Story @ Work – Madras Pharma

T.Nagar

Sholinganallur

• Point to Point and Point to Multi Point• Backhaul spanning to 12kms from T.Nagar (H.O) to Sholinganallur (Factory)

Success Story @ Work – Residency Group Hotels

-Enable Point – to – Point Connectivity ( 1KM )

- Centralized accounting and reservation system

- Hotspot Zones for wireless internet access

Main Building Annexe

Usman Road

• Point – to – Point Connectivity ( 600 meters )

• Enabling centralized billing and accounting systems

Success Story @ Work – GRT Thangamaligai

The complexity of the problem: user prospective

From a user prospective

Multiple Heterogeneous network operators

part of

Multiple user environments accessed using

Multiple heterogeneous devices

owned by

LaptopPDA

UMTS DVB WLAN

heterogeneous users

A Heterogeneous Network Architecture

UTRAN WLAN 4G RAN

PAN

Wireless Access Network

Core Network Future Internet

Intra-Cell PAN Ad-hoc Network PAN PAN

PAN

Re-configurable Technology

What does Reconfiguration mean?

“Reconfiguration refers to the software re-definition and/or adaptation of every

element within each layer of the communication chain.”

BasebandProcessing

UserData

A/D Converter

D/A Converter

RF Front End

Re-configurable Technology

Benefits• Users

• Operators

• Manufacturers

- Select network depending on service requirements and cost.- Connect to any network – Worldwide roaming.-Access to new services.

- Respond to variations in traffic demand (load balancing).- Incorporate service enhancements and improvements.- Correction of software bugs and upgrade of terminals.- Rapid development of new personalised and customised services

- Single platform for all markets.- Increased flexible and efficient production.

Re-configuration Procedures

ReconfigurationTrigger

Mode Identification

Mode Negotiation

Software Download

Mode Switch Decision

ModeMonitoring

ReconfigureTerminal

Initiated by network operator or user

Download software modules that are

required for the target mode

What networks are available?

What is the most suitable network (based on QoS, user preferences etc.)?

Decision on preferred mode

Aggressive frequency re-use High spectrum efficiency

Increased co-channel interference

Downlink Switched Beam Antenna

SIGNALOUTPUT

INTERFERENCE

SIGNAL

SIGNALOUTPUT

BEAMFORMERWEIGHTS

Uplink Adaptive Antenna

SIGNAL

INTERFERENCE

BE

AM

FO

RM

ER

BEAMSELECT

Smart antennas provide substantial interference suppression for enhanced performance

Smart Antennas for 4G• Key enhancement technique to improve system capacity and user experience• Leverage Smart Antennas currently in development/deployment for IS-136 & GSM

Path Loss and Fading Challenge

Delay Spread

Rayleigh Fading

Path Loss

rapid fading of 20 to 30 dB(power varies by 100 to 1000 timesin level at rates of about 100 times per second)

path loss up to ~ 150 dB(that is a 1 followed by 15 zeroes)

Reflected signalsarrive spread outover 5 to 20microsecond

4G Cellular Interference Challenge

0.001

0.01

0.1

1

-5 0 5 10 15 20 25

1|3 reuse

2|6 reuse

3|9 reuse

4|12 reuse

7/21 reuse

Signal to Interference ratio in dB

Cum

ulat

ive

Pro

babi

lity

Each base station is equippedwith three 120 degree directionalantennas to reduce interference& improve capacity

MIMO Measured Channel CapacityPotential Capacity Relative to a Single Antenna System

• Capacity increase close to 4 times that of a single antenna is possible with 4 transmit and 4 receive antennas

• Capacity for pedestrians is similar to mobile users

Space-Time Coding

OFDM for 4G Wireless

~ 6 kHz

~ 800 tones

~ 5 MHz

• OFDM is being increasingly used in high -speed information transmission systems:

- European HDTV- Digital Audio Broadcast (DAB)- Digital Subscriber Loop (DSL)- IEEE 802.11 Wireless LAN

5 MHz channels~ 6 KHz tones~ 13/26 MHz sample rate2048 FFT size (160 usec OFDM blocks)256/512 sample OFDM block guard timeQPSK & 16-QAM modulation adaptive modulation/coding1 to 2 msec time-slots in 20 to 40 msec frames

Mobile OFDM parameters: ex.