1. Wireless Communications
Part 2
April 10, 2000

2. Mobile Radio Systems
mobile originally meant any radio terminal that can be moved during operation
now, portable describes a radio terminal that can be hand-held and used by someone at walking speed (like a portable telephone)
mobile is reserved for a radio terminal attached to a fast-moving vehicle like a car (the familiar cell phone)

3. Global Mobile Radio Systems
CT2 and DECT (Digital European Cordless Telephone) are the two most popular cordless phone standards used in Europe and Asia
NTT in Japan implemented the world’s first cellular system in 1979
in 1981, the Nordic Mobile Telephone system (NMT 450)
Extended European Total Access Cellular System (ETACS) was deployed in 1985 and is very similar to AMPS in the US
GSM (Global System for Mobile) was first deployed in 1991 in a 900 Mhz band designated for all of Europe

4. Mobile Radio Systems
systems can be simplex, one direction only like paging
half-duplex, which allow two-way communication, but one direction at a time because only one channel is provided for transmission and reception
full-duplex provide two simultaneous, separate channels (frequency division duplex) or adjacent time slots on a single channel (time division duplex) for communication to and from the user

5. Mobile Radio Systems: Dividing Spectrum
frequency division multiplexing
each user is allocated a band of the available frequency
time division multiplexing
each user is allocated a slice of time called a carrier

6. Mobile Radio Systems: Dividing Spectrum
code division multiplexing
based on direct sequence spread spectrum
break up a data signal up using a unique pattern for that user and spread their signal

7. Cellular Telephone Systems
carry voice messages via radio frequency channels rather than traditional telephone lines
frequency reuse
by assigning the same frequency in two different cells, the frequency can be reused as long as the cells are sufficiently far apart
low power transmitters and small coverage zones

8. Cellular Telephone Systems
each service area is divided into hexagonally shaped cells
each cell site has a receiver antenna which picks up signals and then transmits them to a computerized mobile telephone switching office (MTSO)
a base station at each cell site receives, transmits, and switches calls to and from any mobile unit in the cell to the MTSO ((hand-off and central control)

9. Cellular Telephone Systems
the MTSO tracks a mobile phone as it moves from cell to cell and takes the signal from the appropriate cell, keeps track of time and billing for each mobile unit
the mobile switching office relays a continual signal from the cell phone to the phone system

10. Mobile Telephony and Cellular Systems
cellular radio telephone
first mobile telephone service introduced in the US in 1946
by 1976, the Bell Mobile Phone Service could accommodate 543 customers in a market of 10 million people in New York
major obstacles were amount of frequency needed for one call, inefficient use of spectrum
concept of breaking a coverage zone into small cells, each reusing portions of the spectrum to increase spectrum usage was implemented in the late 1970s

11. Mobile Telephony and Cellular Systems
first US mobile telephony system AMPS (Advanced Mobile Phone System) was deployed in 1983 by Ameritech in Chicago
in 1991, USDC (US Digital Cellular) system hardware was installed
AMPS has been phased out as users accept digital phones

12. Technologies
analog FM and frequency division multiple access (FDMA) is being replaced by digital modulation and time division multiple access (TDMA)
a cellular service based on CDMA (code division multiple access) has been developed by QualComm and standardized by TIA (Telecommunications Industry Association)

13. Mobile Telephony and Cellular Systems
first generation - early 1990’s
based on analog communication using frequency modulation and frequency division multiple access (FDMA)
AMPS was common in North and South America, Australia and China
second generation technology
developed to use the frequency spectrum more efficiently
digital techniques
time division multiplexing (TDM) or code division multiple access (CDMA)
advanced call processing features like voice mail and call forwarding
GSM

14. Mobile Telephony and Cellular Systems
Third generation - cellular, wireless, and PCS
use CDMA and TDMA and spread spectrum and narrowband digital FDMA
integrate services into one standard
a single handset will support voice, data, and video

15. Mobile Telephony and Cellular Systems
GSM
first implemented in Europe in 1991 to address the problem of many incompatible systems
similar systems now exist in South America, Asia, North Africa, the Middle East, and Australia
over 256 operators in 110 countries
one of its most attractive features is the use of a Subscriber Identification Module (SIM), a portable smart card or plug-in module that identifies the subscriber, rather than the unit
employs data encryption
user data rates of up to 9.6 kbps are supported

16. Mobile Telephony and Cellular Systems
GSM
move into mobile data communications in Europe
plans to develop high speed circuit switched methods to multiplex channels to support large-scale file transfers, fax, mobile video communications

17. CDMA and GSM CDMA has greater capacity than AMPS or GSM
enhanced privacy
technology was originally developed by the military to scramble signals
supports bandwidth on demand
improved coverage characteristics, so fewer cells are needed

18. Wireless Subscribers Ericson’s market share and penetration by country

19. Personal Communication Systems (PCS)
devices range from pagers to personal digital assistants (PDAs) which integrate fax, phone, and information services
predict that half of all Americans will be using PCSs by 2003
England and Germany have systems which were available in 1993 and 1994
still searching for the “killer ap”
users want sufficient bandwidth, access regardless of location, easy, transparent access using a single device

20. Wide Area Data Transmission on a PCS Network
voice and data transmission via cellular or satellite phone networks
mobile computers include laptops, notebook, notepad, pen-based computers, special preprogrammed data collection device
error detection and flow control methodologies are proprietary
little interoperability
lack of third-party vendors

21. Global Wireless Teleworkers
fully mobile groups like sales staff
GTE (USA) sells telecom services and products
service engineers
IBM (UK, Phillipines, USA) for computer maintenance
Honeywell Bull (Australia) for computer maintenance
emergency services
Derbyshire Ambulance (UK), Swedish Police
parcel delivery
Federal Express (Germany, UK, USA)
market researchers

22. Global Wireless Teleworkers
Real estate
ERA Realty (Singapore)
Banking
Co-op Bank (UK), Banco de Brazil
doctors
marketing staff
telecommuters
contractors, architects, tradesmen