ECE 483 Wireless Communication

Instructor: Assist. Prof. Dr. Orhan Gazi

Motivation

• In this lecture our, the fundamental wireless communication systems will be reviewed without going into details.

The electronics Boom

Figure 1.1 The growth of mobile telephony as compared with other popular inventions of the 20 th century.

Current Wireless Systems• Mobile Radio Systems

– Paging Systems– Cordless Telephone Systems– Cellular Telephone Systems

– Bluetooth

– Zigbee/802.15.4 radios

• Wireless LANs (802.11a/b/g, Wi-Fi)• Satellite Systems

• Ultrawideband radios (UWB)

• WiMAX (802.16)

Mobile Radio Systems

• Paging Systems

• Cordless Telephone Systems

• Cellular Telephone Systems

• Bluetooth

• Zigbee/802.15.4 radios

Paging Systems• Broad coverage for (very) short

messaging

• Message broadcast from all base stations

• Simple terminals

• Optimized for 1-way transmission

• No answer-back

Cordless Telephone Systems

Cellular Telephone Systems

• All BSs within a cluster are connected to a Mobile Switching Center(MSC).

• Each MSC of a cluster is then connected to the MSC of other clusters and a PSTN main switching center.

• The MSC stores information about the subscribers located within the cluster and is responsible for directing calls to them.

1G (Analog)

• NMT (Nordic Mobile Telephone) is an analog cellular phone system deployed in more than 40 countries in Europe. The system used originally 450 MHz band (NMT 450), but later when more capacity was needed, it was also adopted for 900 MHz band (NMT 900).

1G (Analog)

• AMPS (Advanced Mobile Phone System) is the analog cellular phone system used in North and South America. AMPS operates at 800 MHz band. AMPS was introduced in the USA in 1983.

• TACS (Total Access Communication System) was developed in Britain using the 900 MHz band. TACS was based on the AMPS system and was adopted in other countries such as Hong Kong and Japan.

• ETACS (Extended Total Access Communication System) was developed in the UK and is available in Europe and Asia.

2G (Digital)

• Uses digital encoding and includes CDMA, TDMA and GSM. Text messages can be sent on 2G networks, but more bandwidth hungry applications require 2.5G.

• Circuit switched• In the United States, GSM, TDMA, and CDMA are

assigned two frequency ranges that include the frequency ranges assigned to analog cellular, 824 MHz to 849 MHz and 869 MHz to 894 MHz, and also the frequency ranges of 1850 to 1910 MHz and 1930 MHz to 1990 MHz.

2G (Digital)

• Uses digital encoding and includes CDMA, TDMA and GSM. Text messages can be sent on 2G networks, but more bandwidth hungry applications require 2.5G.

• Circuit switched• In the United States, GSM, TDMA, and CDMA are

assigned two frequency ranges that include the frequency ranges assigned to analog cellular, 824 MHz to 849 MHz and 869 MHz to 894 MHz, and also the frequency ranges of 1850 to 1910 MHz and 1930 MHz to 1990 MHz.

2G (Digital)

• GSM (Global System for Mobile Communications) is the digital transmission technique widely adopted in Europe and supported in North America. GSM uses 900 MHz and 1800 MHz in Europe. In North America, GSM uses the 1900 MHz band.

• TDMA (Time Division Multiple Access) divides each cellular channel into three time slots in order to increase the amount of data that can be carried. GSM use TDMA. TDMA networks are operated in the United States, Latin America, New Zealand, parts of Russia and Asia Pacific.

2.5G

• An enhancement to 2G networks that allows them to operate in a "packet switched" manner

• 2.5G networks incorporate 2G technology with GPRS' higher speeds to support data transport. 2.5G is a bridge from the voice-centric 2G networks to the data-centric 3G networks.

• GPRS (General Packet Radio Service) is a radio technology for GSM networks that adds packet-switching protocols. As a 2.5G technology, GPRS enables high-speed wireless Internet and other data communications. GPRS networks can deliver SMS, MMS, email, games, and WAP applications.

3G

• 3G networks promise next-generation service with transmission rates of 144Kbps and higher that can support multimedia applications, such as video, video conferencing and Internet access. 3G networks operate on a different frequency than 2G networks.

3G• UMTS (Universal Mobile Telecommunications

System) or WCDM (Wideband Code Division Multiple Access) was selected as the successor to GSM. It is the European standard for 3G wideband digital radio communications, and it utilizes one 5 MHz channel for both voice and data, offering data speeds up to 2 Mbps.

From 1G to Beyond 3G

First Generation

• Analogue• Circuit switched• Basic voice

telephony• Low capacity• Limited local

and regional coverage

Second Generation

• Digital• Circuit switched• Voice plus basic

data applications• Low data speed• Enhancements

towards• packet switching• higher data rates

• Trans-national and global roaming

• Digital• Packet and circuit

switched• Advanced data

(multimedia) applications

• Fast data access• Global coverage• Global roaming

Third GenerationBeyond Third

Generation

• Digital• Packet switched• All IP based (IPv6)• More advanced

multimedia applications

• User in control• Flexible platform

of complementary access systems

• High speed data• Improved QoS• Global coverage• Global roaming

8C32810.61-Cimini-7/98

Bluetooth

• “Cable replacement” RF technology (low cost)• Short range (10 m, extendable to 100 m)• 2.4 GHz ISM band • 1 Data (700 Kbps) + 3 voice channels

• Widely supported by telecommunications, PC, and consumer electronics companies

IEEE 802.15.4/ZigBee radios• Low-Rate WPAN (Wireless Personal Area Network) -

for communications < 30 meters.

• Data rates of 20, 40, 250 kbps

• Star topology or peer-to-peer operation, up to 255 devices/nodes per network

• Support for low-latency devices

• CSMA-CA (carrier sense multiple access with collision avoidance) channel access

• Very low power consumption

Wireless LAN Standards (Wi-Fi)• 802.11b

– Standard for 2.4GHz ISM (industrial, scientific and medical) band (bw 80 MHz)

– Frequency hopped spread spectrum– 1.6-10 Mbps, 500 ft range

• 802.11a– Standard for 5GHz NII band (bw 300 MHz)– OFDM with time division– 20-70 Mbps, variable range– Similar to HiperLAN in Europe

• 802.11g– Standard in both 2.4 GHz and 5 GHz bands– OFDM (multicarrier modulation)– Speeds up to 54 Mbps

In futureall WLAN cards will have all 3 standards...

A roof-mounted Wi-Fi antenna

Satellite Systems

• Cover very large areas

• Different orbit heights– GEOs (39000 Km) via MEOs to LEOs (2000 Km)– Trade-off between coverage, rate, and power budget!

• Optimized for one-way transmission:– Radio (e.g. DAB) and movie (SatTV) broadcasting

• Most two-way systems struggling or bankrupt...– (Too) expensive alternative to terrestrial systems– (But: a few ambitious systems on the horizon)

UltraWideband Radio (UWB) • Impulse radio: sends pulses of tens of picoseconds (10-12)

to nanoseconds (10-9) - duty cycle of only a fraction of a percent

• Uses a lot of bandwidth (order of GHz)

• Low probability of detection by others + beneficial interference properties: low transmit power density over wide bandwidth

• This also results in short range.• But : High data rates, and good positioning.

Why is UWB interesting?

• Unique Location and Positioning properties– 1 cm accuracy possible

• Low Power CMOS transmitters– 100 times lower than Bluetooth for same range/data rate

• Very high data rates possible (although low spectral efficiency) - 500 Mbps at ~10 feet range under current

regulations

• 7.5 Ghz of “free spectrum” in the U.S.

WiMAX: Worldwide Interoperability for Microwave Access • Standards-based (PHY layer: IEEE 802.16 Wireless MAN family/ETSI HiperMAN)

technology, enabling delivery of ”last mile” (outdoor) wireless broadband access, as an alternative to cable and DSL (MAN = Metropolitan Area Network). Several bands possible.

• OFDM-based adaptive modulation, 256 subchannels. TDM(A)-based. Antenna diversity/MIMO capability. Advanced coding + HARQ.

• Fixed, nomadic, portable, and mobile wireless broadband connectivity without the need for direct line-of-sight (LOS) to base station.

• In a typical cell radius deployment of 3 to 10 kms, expected to deliver capacities of up to 40 Mbps per channel, for fixed and portable access.

• Mobile network deployments are expected to provide up to 15 Mbps of capacity within a typical cell radius deployment of up to 3 kms.

• WiMAX technology already has been incorporated in some notebook computers and PDAs.

WiMAX

(Worldwide Interoperability for Microwave Access)

is a trademark for a family of telecommunications protocols that provide fixed and mobile Internet access.

The 2005 WiMAX revision provided bit rates up to 40 Mbit/s with the 2011 update up to 1 Gbit/s for fixed stations.

The name "WiMAX" was created by the WiMAX Forum, which was formed in June 2001 to promote conformity and interoperability of the standard.

The forum describes WiMAX as "a standards-based technology enabling the delivery of last mile wireless broadband access as an alternative to cable and DSL

Data rate

10 kbits/sec

100 kbits/sec1 Mbit/sec

10 Mbit/sec

100 Mbit/sec

0 GHz 2 GHz1GHz 3 GHz 5 GHz4 GHz 6 GHz

802.11a

UWBZigBee

Bluetooth

ZigBee

802.11b

802.11g

3G

UWB

Frequencies occupied

Range

1 m

10 m

100 m

1 km

10 km

0 GHz 2 GHz1GHz 3 GHz 5 GHz4 GHz 6 GHz

802.11a

UWB

ZigBee BluetoothZigBee

802.11b,g

3G

UWB

Power Dissipation

1 mW

10 mW

100 mW

1 W

10 W

0 GHz 2 GHz1GHz 3 GHz 5 GHz4 GHz 6 GHz

802.11a

UWB

UWBZigBee

Bluetooth

ZigBee

802.11bg3G

Spectrum Regulation

• Spectrum is a limited natural resource used by many.

• The worldwide radio spectrum is controlled by ITU-R (International

Telecommunications Union)

• In Europe, by ETSI (European Telecommunications Standardization Institute).

• In the US, by FCC (Federal Communications Commission; commercial) and OSM (Office of Spectral Management; defense).

• Spectrum can be auctioned, paid fixed price for, or “given away”

(unlicensed bands).

• Some spectrum typically set aside for universal use.

Standards

• Interacting systems require standardization (compatibility, interoperability)

• Worldwide standards determined by ITU-T (International Telecommunications Union)

• In Europe, by ETSI (European Telecommunications Standardization Institute)

• In the US by TIA (Telecommunications Industry Association)

IEEE standards often adopted (also worldwide)

• AMPS Advanced Mobile Phone Systems• PCS Personal Communication Service • DECT Digital European Cordless

Telephone• MIRS Motorola’s Integrated Radio

System• POCDAG Post Office Code Standard

Advisory Group• SMR Specialized Mobile Radio Service

HW

• Make an internet search about

“Personal Communications Service”

Find and read some documents about Personal Communications Service

Questions?