Transcript BTS – Communications II

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
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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
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