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Mobile Phone Networks

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ENEE 426 | Communication Networks | Spring 2009 Lecture 9

Basic Organizations

Infrastructure networks

Downlink: tower to phones (forward)

Uplink: phones to tower (reverse)

Arranged into cells

Hence the terminology cell phones

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Cell Towers

Cell towers typically have 3 sectors

Each operates at a different frequency

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Cell Towers

Occasionally local zoning laws prevent towers

from being put up, so they have to becamouflaged

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Cell Towers

Antennas are sectored

Three 120-degree sectors

Each use different frequency, dont interfere

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Cell Sites

At the base of the tower theres the cell site

Contains base station, power, air conditioning

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7/23ENEE 426 | Communication Networks | Spring 2009 Lecture 9

Cellular Backhaul

Connection between cell site

and Mobile TelephoneSwitching Office (MTSO)

Can be fiber, copper, or

wireless

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Cellular History

First-Generation Mobile Phones (1G)

Advanced Mobile Phone System (AMPS)

Analog

Low SNR = static

Unencrypted FCC required support

until Feb 18, 2008

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Evolution to Digital

Second generation (2G)

Two standards emerge (circa 1995) Interim Standard 95 (IS-95), aka cdmaOne

CDMA-base system

Pioneered by Qualcomm who owns CDMA patents

Global System for Mobile communications (GSM)

Originally Groupe Special Mobile, originated in Europe

TDMA system

Other competitors PCS from SprintCDMA at different frequency

iDen from Nextel GSM with push to talk

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GSM Infrastructure

BaseStation

Controller

PacketControl

Unit

MobileSwitching

Center

VisitorLocationRegister

HomeLocationRegister

Public SwitchedTelephoneNetwork

Serving GPRSSupport Node

Gateway GPRSSupport Node

Base TransceiverStation

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GSM Coverage

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CDMA Coverage

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Early Web Access

Phones not designed to

display web pages New protocol developed:

Wireless Application Protocol

Minimal web browsers onphones, web pages designedto support constrainedbrowsers

compressed version of HTTP,runs over UDP

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Higher Data Rates

Evolution of 2.5G -> 2.75G (circa 2003)

Enhanced Data rates for GSM Evolution (EDGE)

Incremental change

Required new base stations and handsets

Same network infrastructure Uses higher-order modulation (3 bits per baud rather than

1 bit per baud)

~ 60 kbps per time slot (up to 8 slots per user =

480 kbps) Eventually classified as a 3G technology

(supports rates > 144 kbps)

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Move toward broadband

Third Generation (3G) standards

Supports >1 Mbps to handsets (official requirement 144 kbps)

Uses different frequencies than 2G

Requires cell companies to build new infrastructure

International Telecommunications Union (ITU) decides whattechnologies are considered 3G

International Mobile Telecommunications-2000 (IMT-2000) is

global standard; major standards:

EDGE (2.75G)

UMTS / W-CDMA

CDMA2000 EV-DO

Mobile WiMAX (IEEE 802.16e)

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GSM 3G Standards (3GPP)

Universal Mobile Telecommunications System

(UMTS) Actually based on Wideband CDMA (W-CDMA)

communications

Most users get 500 kbps to 1 Mbps

Enhancements:

3.5G: High-Speed Downlink Packet Access

Total speeds up to 14 Mbps downlink per base station

Future versions up to 42 Mbps 3.75G: High-Speed Uplink Packet Access

5.76 Mbps uplink speeds per base station

Future versions up to 11.5 Mbps

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CDMA 3G Standards (3GPP2)

CDMA2000 Evolution-Data Only (EVDO)

Uses both CDMA and TDMA Designed for end-to-end IP connectivity

Downlink: 2.4 Mbps (3.1 Mbps future)

Uplink: 153 kbps (1.8 Mbps future)

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Toward 4G

3GPP Standard

Long Term Evolution (LTE) Based on OFDMA

Rates over 320 Mbps with MIMO

3GPP2 Standard Ultra Mobile Broadband (UMB)

Based on OFDMA

Rates over 280 Mbps with MIMO

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Technology Table

Generation 3GPP 3GPP2

2G GSM IS-95 / cdmaOne

2.5G GPRS / EDGE IS-2000 / cdma2000 1xRTT

3G UMTS cdma2000 EV-DO

3.5G HSPA

4G IMT IMT

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ENEE 426 | C i ti N t k | S i 2009 L t 9

Converged Backend

IP Multimedia Subsystem (IMS): backend convergence of voice and data

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