1. “RECENT TRENDS IN WIRELESS COMMUNICATION”

2. Outline Objective and Introduction
Wireless time-line and initial technologies
Current Generations
Modern Wireless Systems
Comparison of various technologies
Conclusion and References

3. Objectives
Where is wireless broadband today? Where has it come from in the last decade? What is its future potential?
How do they feature in modern/emerging wireless systems (Wifi: a/b/g/n, 3G, mobile WIMAX: e)?
Modern wireless systems – WiFi , Bluetooth, Zibgee, 3G, GSM, CDMA, WiMAX, UWB,. .

4. Why Wireless? Characteristics Mostly radio transmission Advantages
Spatial flexibility
Ad hoc networks
No problems with wiring
Robust against disasters like earthquake, fire
Disadvantages
Low transmission rates for higher no. of users
Many national regulations, global regulations
Restricted frequency range, interferences of frequencies
Nevertheless, in the last years, it has really been a wireless revolution…

5. Wireless Evolution Timeline

6. Early Wireless Systems
1st Generation: Analog: early 80s
AMPS: FDMA with 30 KHz FM voice channels.
FCC increased the cellular spectral allocation from 40 MHz to 50 MHz.
Two 25MHz channels: DL and UL (FDD)
Drawbacks:
Analog - very susceptible to static and noise
2nd Generation: digital: early 90s
higher capacity, improved cost, higher data rates for support of digital services,
TDMA provides up to 120 channels
Interference-free wireless operation ~100 to 500 mts outdoor
Average data transmission: 1.2 Mbps

7. 2G Cellular Systems GSM (Global System for Mobile) fully digital
Specifications:
fully digital
900MHz or 1800 MHz
124 channels
Automatic location,
hand-over, frequency reuse
Services: data with
9.6kbps, voice
Transmission power
in handset: max. 2 W
IS-95 - uses direct-sequence CDMA with binary modulation and coding.

8. Wi-Fi
Local area networking technology designed to provide in-building or campus broadband coverage
Based on IEEE a/b/g/n standards
Much higher peak data rates + larger bandwidth (20 MHz)
Beyond buildings: Metropolitan-wide (Muni-Fi), Neighborhood Area Networks (NaN), hotspots
Covers greater distances
Wi-Fi systems - not designed to support high-speed mobility.

9. IEEE 802.11 Standards Standard Date Scope IEEE 802.11 1997
Medium Access Control (MAC): One common MAC for WLAN applications
Physical Layer: Infrared at 1 and 2 Mbps
Physical Layer: 2.4 GHz FHSS at 1 and 2 Mbps
Physical Layer: 2.4 GHz DSSS at 1 and 2 Mbps
IEEE a
1999
Physical Layer: 5 GHz OFDM at rates 6 to 54 Mbps
IEEE b
Physical Layer: 2.4 GHz DSSS at 5.5 and 11 Mbps
IEEE g
2003
Physical Layer: Extended b to data rates > 20 Mbps
IEEE n
ongoing
Physical / MAC:Enhancements to enable higher throughput

10. Bluetooth Short range communication technology
Short distances {10m (1mW), 100m (100 mW)}
Lower power than Wi-Fi
Connect and exchange info – mobile phones, PC, laptops, GPS receivers,
2.4 GHz band
Data rate of 1 Mbps
small –scale applications
Frequency-hopping for multiple access with a carrier spacing of 1 MHz for 8 devices

11. 2.5 G and 2.75 G GPRS (General Packet Radio Service)
packet oriented Mobile data service to users of GSM
Data rates: from 56 up to 114 kbps
Services – MMS, SMS, Internet application through WAP
EDGE (Enhanced Data rates for GSM Evolution)
Extension on standard GSM
increases data rates (up to kbps for 4 timeslots) using a high-level modulation format combined with FEC coding.
CDMA 2000
Hybrid 2.5G/3G technology
CDMA for digital radio, voice, signaling data,.

12. WLAN Linking of two or more computers or devices using OFDM modulation
Communication in a limited area + mobility
Convenient, cost efficient, ease of integration with other networks and network components
Typical range – in order of tens of meters – sufficient for home, but insufficient for larger structure
Speed Mbps – slow compared to slowest common networks(100 Mbps to several Gbps)

13. WiMAX (IEEE )
WiMAX - Worldwide Interoperability for Microwave Access
Wireless transmission of data - from point-to-point links to portable internet access
2 Mbps symmetric broadband speed
– fixed WiMAX – no support for mobility
802.16e-2005 – mobile WiMAX – support for mobility
Applications:
Connecting Wi-Fi hotspots to internet
Wireless alternative to cable and DSL for broadband access
Data and telecommunication services
Portable connectivity

14. COMPARISON

15. Ultra Wide Band (UWB)
Objective – transmit large amount of digital data - over a wide spectrum of freq bands - very low power, short distance.
Fractional bandwidth: W/fc >=20%, or more than 500 MHz of absolute bandwidth
Operating range: 3.1 GHz to 10.6 GHz
Limited transmit power of -41 dBm/MHz
1.6
1.9
2.4
Bluetooth,
802.11b
Cordless Phones
Microwave Ovens
GPS
PCS 5
802.11a
-41 dBm/Mhz
“Part 15 Limit”
UWB
Spectrum
Frequency (Ghz)
Emitted
Signal
Power
10.6
3.1

16. UWB Communication
UWB is an 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 (GHz)
Modulation - OFDM
Excellent ranging capability; Synchronization (accurate/rapid) an issue.
Impulse
Modulation 3 10
GHz
frequency
Ultrawideband
Communication
time 1
(FCC Min=500Mhz)

17. UWB Applications
Short range, indoor applications - high data rates, low power
‘see-through-the-wall’ precision radar imaging technology,
Precision locating and tracking, etc
Most computer and consumer electronic devices require wires to play, record or exchange data. UWB – eliminates wires
Play a just recorded video on a HDTV without wires
A portable MP3 player
could stream audio to
speakers anywhere
Mobile computer-digital
projector wirelessly

18. ZigBee (IEEE )
Objective – develop products that are v.low cost, low data rate
Very low power consumption (no recharge for months or years!), up to 255 devices
Data rates of 20, 40, 250 kbps
CSMA-CA channel access
Frequency of operation in ISM bands
868 MHz in Europe,
915 MHz in USA, Australia
2.4 GHz worldwide
Home automation, consumer electronics applications, RFID/tagging applications (supply-chain), Hospital care

19. Data rate 100 Mbit/sec UWB 802.11g 802.11a 802.11b 10 Mbit/sec
Bluetooth
100 kbits/sec
ZigBee
ZigBee
10 kbits/sec
UWB
0 GHz
1GHz
2 GHz
3 GHz
4 GHz
5 GHz
6 GHz

20. Range 10 km 3G 1 km 100 m 802.11b,g 802.11a Bluetooth 10 m ZigBee
UWB
1 m
UWB
0 GHz
1GHz
2 GHz
3 GHz
4 GHz
5 GHz
6 GHz

21. Conclusion
Wireless Technology – rapidly growing and generating tremendous changes in telecommunications and networking
Data transmission rates increased tremendously from 9.6 kbps (GSM) to 2Mbps (WCDMA), increasing more than 200 times within last 10 years
More ambitious 4G – approximately 1 Gbps
But, despite many promising technologies, the reality that
… services many users at high data rates …
…. (fixed and mobile) …
… with reasonable bandwidth and power resources…
… while maintaining high coverage and quality of service
….. has not yet been achieved.

22. References
Internet Resources
BOOKS
William Stallings; Wireless Communications & Networks; Pearson Pentice Hall, India, 2008 (Second edition)
Hsiao-Hwa Chen, Next Generation Wireless Systems and Networks; John Wiley & sons Ltd, Great Britain, 2006
Articles
Rafael Kolic; Ultra Wideband – the Next-Generation Wireless Connection

23. ANY QUERIES ?