Lecture 01 EEE 441: Wireless And Mobile Communications BRAC University

Prerequisites Required:  EEE 341: Introduction to Communication Engineering, with grade C or better Recommended:  CSE 320: Data Communications  CSE 421: Computer Networks

Marking Scheme Participation: 5% HW and Quizzes: 25% Midterm: 20% Final: 50%

Course Rules Every HW / Quiz will count No choice likely on exams

Textbook Theodore Rappaport, “Wireless Communications: Principles and Practice”, 2nd ed., Prentice Hall, 2001 This is the standard text on wireless communication; buy it immediately!

Policy on Late Submissions Every HW due following week, lab report due following week

Studying Advice Course is 50% descriptive, 50% mathematical Course is front-loaded So lots of early studying needed!

Let us begin …

Wireless Communication Transmitting voice / data using electromagnetic waves in open space Electromagnetic waves: Travel at the speed of light (c = 3x10 8 m/s) Has a frequency (f) and wavelength ( )  c = f High frequency means high energy photons High energy photons mean more penetrability

The Electromagnetic Spectrum IRUVX-Rays Cosmic Rays Radio Spectrum 1MHz  100m 100MHz  1m 10GHz  1cm < 30 KHz VLF KHz LF 300KHz – 3MHz MF 3 MHz – 30MHz HF 30MHz – 300MHz VHF 300 MHz – 3GHz UHF 3-30GHz SHF > 30 GHz EHF Micro wave Visible light

Wavelength of Some Popular Technologies GSM Phones  frequency ~ 900 Mhz  wavelength ~ 33cm PCS Phones (US mobile technology)  frequency ~ 1.8 Ghz  wavelength ~ 17.5 cm Bluetooth  frequency ~ 2.4Gz  wavelength ~ 12.5cm

Carriers and Channels  The information from sender to receiver is transmitted over a well defined frequency band  This is called a channel  Each channel has a fixed channel bandwidth (in Hz)

Simplex Communication Normally, a station can transmit only in one way  This is called simplex transmission To enable two-way communication:  called full-duplex communication  may be performed using Frequency Division Duplexing (FDD) Time Division Duplexing (TDD)

Duplex Communication: FDD FDD: Frequency Division Duplexing Base Station B Mobile Terminal M Forward Channel Reverse Channel Forward Channel and Reverse Channel use different frequency bands

Duplex Communication: TDD TDD: Time Division Duplexing Base Station B Mobile Terminal M A singe frequency channel is used. The channel is divided into time slots. Mobile station and base station transmits on the time slots alternately. MBMBMB

Frequency Spectrum Allocation in USA Cellular Radio Service … … … … MHz MHz Reverse ChannelForward Channel Channel NumberCenter Frequency (MHz) Reverse Channel 1 <=N <= <= N <= 1023 Forward Channel 1 <=N <= <= N <= N (N-1023) N (N-1023) (Channels are unused) Channel bandwidth is 45 MHz

Mobility vs Portability Initially the Internet and Telephone Networks were designed assuming static user terminals A terminal accesses the network always from a fixed location No change of location during a call Mobility and portability  Portability means changing point of attachment to network offline  Mobility means changing point of attachment online

Degrees of Mobility Walking Users Low speed Small roaming area Vehicles High speeds Large roaming area

Example Personal Communication Services (PCS) Systems High-tier Systems  GSM: Global System for Mobile Communications The most common mobile telephony system  IS-136 USA digital cellular mobile telephony system TDMA based multiple access  IS-95 CDMA based multiple access

Example PCS systems (cont’d)‏ Low-tier systems  Residential, business and public cordless access applications and systems Cordless Telephone 2 (CT2) :  EU standard, FDMA Digital Enhanced Cordless Telephone (DECT)‏  EU standard, TDMA Personal Access Communication Systems (PACS)‏  US standard, TDMA/FDMA Personal Handyphone System (PHS)‏  Japan standard, TDMA

Example PCS systems (cont’d)‏ Wideband wireless systems  For Internet access and multimedia transfer CDMA2000 W-CDMA 3G

Example PCS systems (cont’d)‏ Other PCS (Personal Communication Systems)  Special data systems CDPD: Cellular Digital Packet Data Advanced Radio Data Information System (ARDIS)‏  Paging Systems  Mobile Satellite Systems  ISM band systems: Bluetooth, Wi-Fi, etc.

PCS System Problems How to integrate mobile and wireless users to the Public Switched Telephone Network (PSTN) (Voice Network) Cellular mobile telephony system How to integrate mobile and wireless users to the Internet (Data Network) Mobile IP, DHCP, Cellular IP How to integrate all of them together and also add multimedia services (3G Systems)

GSM and CDMA Coverage Map Worldwide

Major Mobile Radio Standards: US 300DQPSK TDMA/FDMA1994Cordless/PCS PACS 200GMSK TDMA1994PCS DCS-1900 (GSM)‏ 154-FSKSeveralSimplex1993Paging FLEX 1250QPSK/BPSK CDMA1993Cellular/PCS IS-95 30GMSK FH/Packet1993Cellular CDPD 30DQPSK TDMA1991Cellular USDC 30FM FDMA1983Cellular AMPS Channel BW (KHz)‏ ModulationFrequency Band (MHz)‏ Multiple Access Year Intro TypeStandard

Major Mobile Radio Standards: EU 100GFSK FDMA1989Cordless CT2 200GMSK TDMA1993Cordless/PCS DCS GFSK TDMA1993Cordless DECT 254-FSKSeveralFDMA41993Paging ERMES 20-10FM FDMA1985Cellular C KHzGMSK TDMA1990Cellular/PCS GSM 12.5FM FDMA1986Cellular NMT FM900FDMA1985Cellular ETACS Channel BW (KHz)‏ ModulationFrequency Band (MHz)‏ Multiple Access Year Intro TypeStandard

Notices Reading:  Rappaport, Ch  Handout on lesson plan