Long distance wireless link

Long Distance Links Ermanno Pietrosemoli Fundación EsLaRed University of Los Andes

Contents ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Introduction ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

What do we need for long distance links? ,[object Object],[object Object],[object Object]

[object Object],[object Object],How de we improve the power budget? ,[object Object],[object Object],Threshold Rx Gr Tx Gt At Ar Pr Pt Free Space Loss dBm km L= 92,4 +20 log(d/km)+20 log(f/GHz) Margin

[object Object],[object Object],[object Object],How do we improve the power budget?

Antenna Alignment ,[object Object],[object Object],[object Object],[object Object]

[object Object],Antenna Alignment

[object Object],[object Object],[object Object],[object Object],Antenna Alignment Suggested tools: Network Stumbler is a very useful program for measuring both the received signal level and the noise

[object Object],[object Object],[object Object],Antenna Alignment Suggested tools: ,[object Object],clinometer

[object Object],[object Object],Antenna Alignment Preparation:

Antenna Alignment Field Work: ,[object Object],[object Object],[object Object],Visual Alignment Marco Zennaro and Tomas Krag

Antenna Alignment ,[object Object],[object Object],[object Object],Visual alignment. Javier Triviño

Antenna Alignment False Maximum: ,[object Object],Antenna radiation pattern

Vertical Antenna Alignment AA Elevation adjustment ,[object Object]

Antenna Alignment ,[object Object],[object Object],[object Object]

Magnetic and geographic bearing ,[object Object]

Magnetic Declination ,[object Object],[object Object],[object Object],[object Object],[object Object],C Compass and geographic north landmark El Baúl, Venezuela

Antenna Alignment ,[object Object],[object Object],[object Object],Google Earth map: www.google.com

[object Object],[object Object],Antenna Alignment

Antenna Alignment When the remote end is NOT visible: ,[object Object],[object Object],[object Object]

Antenna Alignment ,[object Object],Antenna Alignment using instruments 30 dBi Antenna 30 dBi Antenna FSL= 149 dB @ 279 km HP 8594E S. Analyzer EIRP= 56 dBm HP 8648C Signal Gen. Fc= 2400 MHz Amp. 500 mW Pr = -66 dBm Span = 10 MHz 1 dB cable loss 1 dB cable loss

[object Object],[object Object],Antenna Alignment ,[object Object],Received tone at 382 km

Antenna Alignment: Low cost analyzer ,[object Object],[object Object],[object Object]

Antenna Alignment ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Media access techniques ,[object Object],[object Object],[object Object],[object Object]

Antenna Alignment Software for antenna alignment

Medium Access Mechanism ,[object Object],[object Object],Source: WiLDNet: High performance WiFi-based Long Distance (WiLD) Networks, Sonesh SuranaTIER, UC Berkeley , 2007.Community Wireless Summit , May 18, 2007 , Loyola College, Columbia, MD

Medium access mechanism ,[object Object],Source: WiLDNet: High performance WiFi-based Long Distance (WiLD) Networks, Sonesh SuranaTIER, UC Berkeley , 2007. Community Wireless Summit , May 18, 2007 , Loyola College, Columbia, MD Throughput Vs distance for a point to point WiFi link. Note that eliminating the waiting for ACKs the throughput becomes independent of distance.

Medium acces mechanism ,[object Object],[object Object],[object Object]

79 km link Profile of the 79 km link. The throughput with radios using the TIER modification was as predicted

280 km link ,[object Object],Profile for the 280 km. Propagation time is 2 ms.

The 5 GHz band ,[object Object],[object Object],[object Object]

The 5 GHz band ,[object Object],[object Object]

The 5 Ghz band ,[object Object],[object Object],[object Object],[object Object]

The 5 GHz band I do not know of any low cost device for antenna alignment in this frequency band Please let me know if you find any suitable device

The 5 GHz band 5,8 GHz link. Although only 16 kilometers long, one of the ends is at 4765 m altitude and transmits the output of a webcam pointed at Pico Bolívar, at 5000 m altitude. Operational since 2002 http://www.eslared.org.ve

Conclusions ,[object Object],[object Object],[object Object],[object Object]

Conclusions (cont.) ,[object Object],[object Object]

Long distance wireless link

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