This chapter shows how a real Aruba indoor test facility was planned using both VisualRF Plan and a traditional site survey. The test facility is shown in Figure 21. This facility is used primarily by the Aruba technical marketing team to test products in larger scale environments. This floor plan is a typical open floor plan that consists of large numbers of cubicles and a limited number of offices and meeting rooms. Using the Environmental Assessment process explained in Chapter 3: Environmental Evaluation, we would assign this a low complexity status. This type of floor plan is ideal for software-based planning.
Figure 21 Proof of concept lab test facility
This facility will be the basis of the planning for both VisualRF Plan and the Site Survey chapters later in this guide. Other key environmental assessment inputs that affect the design are explained in Table 2. If you want to practice by replicating this example yourself, the graphic of the floor plan is available on the VRD page at http://www.arubanetworks.com/vrd.
Table 2 Building Data
Building Dimensions | |
---|---|
Width | 162 feet |
Length | 185 feet |
Number of Floors | 1 |
User and AP Information | |
Number of Users | 180 |
Devices per User | 2 |
Devices per Radio | 20 |
Radio Type(s) | 802.11a/b/g/n |
AP Model | AP-105 |
AM Model | AP-93 |
Client Data Rates | |
802.11b/g/n (2.4 GHz) | 150 Mb/s (20 MHz HT Channels) |
802.11a/n (5 GHz) | 300 Mb/s (40 MHz HT Channels) |
The simple goal of an RF site survey is to accurately determine how many APs are necessary to provide a targeted minimum data rate in a given area. The survey also helps to identify where to place the APs to enable optimum performance. AP coverage can be modeled in a virtual site survey in many open office environments. Most indoor APs except the AP-93H emanate RF energy in all directions in the horizontal plane, so that the area covered by the AP using an omnidirectional antenna is a circle, with vertical as well as horizontal coverage as shown in Figure 22.
Figure 22 Theoretical RF propagation characteristics
RF coverage in the actual world differs from that of theoretical coverage, due to factors like environmental conditions, obstructions, and interference that all affect RF energy propagation. RF behavior is notoriously difficult to accurately predict in challenging environments. Environments that are more complex are more likely to require a physical site survey. Figure 23 depicts an environment where many RF obstructions exist and may require a site survey for optimal performance.
Figure 23 Realistic RF propagation characteristics
The term “site survey” is really a category of activities that means different things to different people. Consulting firms and wireless integrators that provide engineering services generally offer four different types of RF site surveys. A virtual survey typically is performed in low-complexity environments, such as relatively new constructions with primarily cubicles for employees. Passive and active surveys typically are used in higher-complexity deployments. Spectrum clearing surveys are done to evaluate the level of non-WiFi interference that may be encountered in a location. Table 3 describes the basic types of site surveys.
Table 3 Types of Site Surveys
Virtual Survey | Passive Survey | Active Survey | Spectrum Clearing | |
---|---|---|---|---|
Description | Uses customer-supplied building drawings in JPG, PDF, or DWG format to place APs | Involves passive data collection of the ambient RF environment (no active testing) based on actual RF data | Involves active testing of real APs throughout a facility (indoor or outdoor) to determine the actual AP coverage footprint and RF hazards | Same as active RF survey, but also includes a spectrum analysis at each active test location |
Location | Remote | Onsite (typically indoors) | Onsite | Onsite (typically indoors) |
Deliverables | Marked-up JPG file indicating AP locations and controller location codes Site bill of materials | Heat maps of existing 2.5 GHz and 5 GHz RF environment Marked-up JPG showing AP locations Summary narrative analysis | Heat maps of test APs with actual measured coverage Marked-up JPG showing AP locations Detailed data analysis | Pinpoint locations of the 2.4 GHz and 5 GHz interference sources |
Accuracy | * | ** | *** | **** |
Cost | $ | $$ | $$$ | $$$$ |
The following chapters describe each of these survey types in detail.