Wireless Site Survey Scope and Assumptions
Introduction and Methodology
Topgallant Partners will produces a complete wireless site survey for our customers per the maps and building plans.
The site survey will serve as a deployment model for the correct placement of Access Points; coverage area of those AP’s and bandwidth availability of the AP’s based on drawings provided by Our customers.
Desired Coverage Area Requirements
It is assumed Our customers require seamless full RF coverage for parts of its health system located in Concord, New Hampshire. A reasonable coverage “hole criterion” is between 2 and 10 percent. This means that between two and ten test locations out of 100 random test locations may receive marginal service.
Based on this RF Site Survey Topgallant will identify these coverage areas and report them to Our customers IT manager and RTM, allowing them to tune the Wireless Network and minimize the size of uncovered areas and improve service.
Desired Average Client Throughput Requirements
The desired average user throughput is yet to be determined but best practice put this average at 11 Mbps to 130 Mbps. Average client throughput are related to the 802.11 protocols and signal strength and Access Point (AP) density. (This will need to be determined prior to commencement of services.)
For reference and In terms of protocol, 802.11b can support an average user throughput of up to 6 Mbps and 802.11g can support a typical average user throughput of up to 20 Mbps with reasonable radio densities. 802.11n can provide increased throughput, but at a cost of decreased channel capability. (We strongly discourage that 802.11n be used in the 2.4 GHz frequency, based on this decreased performance.)
Generally, the stronger the signal, the higher the client throughput; There is a point above which a stronger signal does not increase client throughput. For 802.11b/g/n networks, this point is typically -75 dBm, above which average client throughput is 5 to 6.5 Mbps regardless of increase in signal strength.
For 802.11a/n networks, this point is typically between -50 dBm and -60 dBm, above which average client throughput is 24 to 130 Mbps regardless of increase in signal strength. Note that for 802.11a/n, the range over which the average client throughput improves is between -80 dBm and -50 dBm. Please note that the more dense APs are placed the more likely for AP to AP co-channel interference will occur.
Voice over IP Requirements
Please note that when deploying 802.11 wireless LANs to support Voice over IP (VoIP) telephones a few special considerations are needed in the deployment process. When deploying a Wi-Fi voice system, seamless full coverage with an average user throughput of 5 Mbps or more should be used. Areas such as stairways, bathrooms, cafeterias and outside areas may require special consideration and additional access points. These are areas that are not typically critical for data users but are critical coverage areas for voice users who want seamless coverage.
Building Type
In determining how many radios and types of antennas that will be needed for our customers’ Campus; we will need to conduct an initial walk through to identify the building type and its RF characteristics; the following table shows the five basic areas that are common.
- Open Office: No walls at all and short cubes only.
- Cubes and Walled Offices: Combination of cubes and some walled office.
- Drywall Only: Mostly dry walled offices.
- Open Warehouse Type Areas
- Outside Areas
Buildings inside Our customers Properties will be evaluated through building diagrams for the RF Site Survey. Outside Areas will be evaluated via Diagrams and Maps provided by Our customer. Topgallant Partners will use GPS technologies to ensure proper location coverage.
Our customer’s building drawings and Maps will need to be provided to Topgallant and will be used in our deliverable.
Best Practices Assumptions
The guidelines in the RF site survey are based on the following conditions and assumptions:
- Client Data Terminal Transmit (Tx) Power: >=15 dBm.
- Client Data Terminal Antenna Gain: >=0 dBm.
- Receiver sensitivity = -89 dBm with 10 % packet error rate.
- Environmental noise floor = -85 dBm.
- Capacity: up to 15 Data client Terminals or up to 14 VoIP clients per AP.
- Client Data Terminal Transmit (TX) Power: >=15 dBm.
- Handover Times: 37 milliseconds or less for Layer 2 handovers, 48 milliseconds or less for Layer 3 handovers.
- Quality of Service: Assigned on a per-WLAN basis. VoIP clients precedence (90+% of bandwidth) over data only clients.
RF Computer Aided Design and RF Site Survey
The methodology used for this RF site survey consists of importing the floor plans of the coverage area into a Computer Aided Design provided by Ekahau Professional Site Survey Software in which we can place virtual access points, draw in the walls of the building and assign RF characteristics to the walls. The on-site WLAN survey will be used to verify assumptions.
Specific Customer Assumptions/Requirements:
APs must be deployed via CAT 5 Ethernet Cabling. New Deployments will most likely require new cabling. To streamline the deployment of the Wireless APs, CAT 5 Ethernet Cabling will need to be deployed to the specific APs. The CAT 5 Cabling will provide the interconnection to the network and provide Power over Ethernet to power the APs.
Secondly, wiring closets must be within 100 Meters of Access Points and can provide the space, power, environmental attributes security and Gigabit Access via 1000SX or 1000TX to the existing network.
Coverage Methodology
Our customers should seek best and balanced coverage areas. This reduces the chances of intentional or unintentional intrusion from outside the area as well as interference from outside sources. It also significantly increases the amount of available bandwidth on the wireless network. Proper placement and measurement of signal strength will be accomplished in the on-site survey.
We will require that Our customers provide User Counts, Desired Throughput and Data Types to assist in proper design and evaluation for WLAN Deployment.