“RECENT TRENDS IN WIRELESS COMMUNICATION”

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

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: 802.11a/b/g/n, 3G, mobile WIMAX: 802.16e)? Modern wireless systems – WiFi , Bluetooth, Zibgee, 3G, GSM, CDMA, WiMAX, UWB,. .

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 10-20 years, it has really been a wireless revolution…

Wireless Evolution Timeline

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

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.

Wi-Fi Local area networking technology designed to provide in-building or campus broadband coverage Based on IEEE 802.11a/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.

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 802.11a 1999 Physical Layer: 5 GHz OFDM at rates 6 to 54 Mbps IEEE 802.11b Physical Layer: 2.4 GHz DSSS at 5.5 and 11 Mbps IEEE 802.11g 2003 Physical Layer: Extended 802.11b to data rates > 20 Mbps IEEE 802.11n ongoing Physical / MAC:Enhancements to enable higher throughput

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

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 236.8 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,.

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 1-108 Mbps – slow compared to slowest common networks(100 Mbps to several Gbps)

WiMAX (IEEE 802.16) WiMAX - Worldwide Interoperability for Microwave Access Wireless transmission of data - from point-to-point links to portable internet access 2 Mbps symmetric broadband speed 802.16-2004 – 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

COMPARISON

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

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)

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

ZigBee (IEEE 802.15.4) 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

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

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

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.

References Internet Resources http://en.wikipedia.org/wiki/Wireless http://www.intel.com/technology/comms/uwb http://www.networkworld.com/news/tech/2002/0225tech.html http://en.wikipedia.org/wiki/3GPP_Long_Term_Evolution http://en.wikipedia.org/wiki/ZigBee 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

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