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BTS – Communications II

Requirements and Technologies

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BTS Communication

• Requirements– Redundant links for robustness– Terrain and distance dependent– Compatible/non-interfering with existing systems

• Technologies– Satellite– RF, Microwave– Fiber-optic– Commercial phones (land lines and wireless– IP Links

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Satellite Orbits

• Low Earth Orbit (LOE) – 200- 1000 Miles Above Ground Level – .03 Second Roundtrip Latency for Upload and

Download – Used by military satellites

• Middle Earth Orbits (MEO) – 6250 - 13000 Miles Above Ground Level – .06 to .14 Second Roundtrip Latency

• Geo-synchronous Orbit – 22,300 Miles Above Ground Level – .24 Second Roundtrip Latency – Used by most commercial satellites

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Satellite Remote Sensing

• Optical • Radar

– Insensitive to weather– Sensitive to ground conditions

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Microwave Links

• Benefits:– No need to dig– Only option over inhospitable terrain or congested

areas – Despite low cost, broadcast level video quality

• COFDM (Coded Orthogonal Frequency Division Multiplex) helps in the noisy urban areas

– Excellent for ad hoc deployment

• Specs– Single channel (To collecting points)– Multi-channel

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Typical Setup

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Microwave Repeaters

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COFDM Advantages

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Advanced Microwave Setup

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Advanced Microwave Setup (Relay)

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New Technologies

Courtesy: ParcelCall

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Generations of Wireless Technologies

• 1G: 1979-1992 analog wireless technology• 2G: current digital wireless technology

– TDMA (GSM: Global Systems of Mobile Communication) – CDMA

• 2.5G: interim technology accommodates graphics

• 3G: non-IP based technology (2001-2005) supports rich media (video clips)

• 4G: fully IP-based network (2006-2010)• GPRS: General Packet Radio Services• WCDMA: Wideband CDMA

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Wireless Technologies (Cont’d)

• GPS: Satellite-based Global Positioning System• SMS: Short Message Service (e-mail, up to 160

characters)• EMS: Enhanced Messaging Service

– Extension of SMS; simple animation, tiny picture, short melody

• MMS: Multimedia Messaging Service– Rich media of next generation

• UMTS: Universal Mobile Telecommunications System for 3G mobile standard

• WAP: Wireless Application Protocol for Internet Browsing

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Automated Vehicle Location (AVL)

• GPS to track vehicles• Already more than a million vehicles in

the US with AVL • $3 billion business by 2007• In line with the new vision for BTS

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New Interesting Proposals

• Airships– Comparison with UAVs, Satellites