A crucial step in the LANPlanner process is formatting of the CAD drawing. In this step, LANPlanner creates a model of RF signal penetration and attenuation based upon the characteristics of the structure as recorded in the drawing. Especially important are the characteristics of any obstructions (walls, racks, cages, etc.) within the targeted areas of coverage. Using a knowledge base of attenuation values for specific construction materials, LANPlanner can predict expected coverage for a given AP placement – taking signal loss due to obstructions fully into account – and, thereby, produce an RF infrastructure plan. To do this accurately, though, the customer must provide accurate data regarding obstructions, including material types and obstruction dimensions. The best results occur when this data is already stored in the CAD drawing files.This customer is a manufacturer and distributor of gaskets. They provided a CAD drawing (SEE DRAWING 1) with building dimensions; however, information regarding internal obstructions was not supplied. Since a coverage prediction was only needed for the two warehouse areas of the facility, though, the data provided was adequate to generate a sufficient model. Area one of the warehouse is approximately 19’ high, 145’ in length, and 100’ in width; the second area is approximately 19’ high, 110′ in length and 140′ in width.
After the formatting process, LANPlanner calculates optimal Access Point/Port placement. In this case, LANPlanner called for 2 Motorola AP650’s with 6 small 5dBm gain Omni Antenna’s for each AP. These were installed in the designated locations, 17′ from the floor (SEE DRAWING 2). In the drawing, each AP650 is represented by a colored dot:Black represents channel 1; Red represents channel 6. Note: For 802.11b/g networks, channels 1, 6, & 11 are the only non-overlapping channels. LANPlanner always attempts to use these channels to minimize radio interference.
In addition to calculating optimal AP placement, LANPlanner also predicts the resulting RSSI (Received Signal Strength Indication), SNR (Signal to Noise Ratio), Channel allocation, and throughput for any given location within the area of coverage. These predicted results are displayed graphically in the form of a heat map (SEE DRAWING 3). In the colored heat map drawing of the warehouse, each color represents different RSSI/throughput levels: RED is -50dBm (dBm is the RSSI power ratio in decibels) or 48Mbs-54Mbs of throughput; YELLOW is -60dBm or 36Mbs -48Mbs of throughput; GREEN is -70dBm or 24Mbs-36Mbs of throughput.
In this example, since obstruction information was not given, the LANPlanner prediction assumed the areas to be covered as open free space. Once the backbone was installed, actual RSSI/throughput values were measured to insure adequate coverage was achieved. In this case, no adjustments to AP placement or configuration were required.