User guide

DESIGNING YOUR CANOPY NETWORK
12 Engineering Your RF Communications ................................................................ 96
12.1 Anticipating RF Signal Loss ........................................................................... 96
12.1.1 Understanding Attenuation............................................................................96
12.1.2 Calculating Free Space Path Loss................................................................96
12.1.3 Calculating Rx Signal Level...........................................................................96
12.1.4 Calculating Fade Margin ...............................................................................97
12.2 Analyzing the RF Environment....................................................................... 98
12.2.1 Mapping RF Neighbor Frequencies ..............................................................98
12.2.2 Anticipating Reflection of Radio Waves ........................................................99
12.2.3 Noting Possible Obstructions in the Fresnel Zone........................................99
12.2.4 Radar Signature Detection and Shutdown..................................................100
12.3 Considering Frequency Band Alternatives................................................... 100
12.3.1 900-MHz Channels......................................................................................101
12.3.2 900-MHz Single AP Available Channels.....................................................101
12.3.3 2.4-GHz Channels.......................................................................................101
12.3.4 5.2-GHz Channels.......................................................................................102
12.3.5 5.4-GHz Channels.......................................................................................102
12.3.6 5.7-GHz Channels.......................................................................................103
12.3.7 5.8-GHz Channels Available for 45-Mbps Backhaul Module......................104
12.3.8 Example Channel Plans for AP Clusters.....................................................104
12.3.9 Multiple Access Points Clusters ..................................................................106
12.4 Selecting Sites for Network Elements .......................................................... 107
12.4.1 Resources for Maps and Topographic Images ...........................................107
12.4.2 Surveying Sites............................................................................................108
12.4.3 Assuring the Essentials...............................................................................108
12.4.4 Finding the Expected Coverage Area .........................................................109
12.4.5 Clearing the Radio Horizon .........................................................................109
12.4.6 Calculating the Aim Angles .........................................................................109
12.5 Collocating Canopy Modules........................................................................ 110
12.6 Diagramming Network Layouts .................................................................... 111
12.6.1 Accounting for Link Ranges and Service Coverage....................................111
12.6.2 Accounting for Data Handling Requirements..............................................113
12.6.3 Avoiding Self Interference ...........................................................................114
12.6.4 Avoiding Other Interference ........................................................................115
13 Engineering Your IP Communications ............................................................... 116