Conducting a Site Survey
Site surveys differ depending on the size of the survey site.
- Smaller sites are surveyed for one or two access points to provide coverage
over a space no larger than a single room.
- Medium sites could require between 10 and 20 access points for the size of a
warehouse or several rooms.
- Large sites could require between 20 and 100 access points for a large
building with different radio coverage service areas in different parts of the
building.
Discuss any special installation requirements. Determine the types of cables
to be connected to the access points (Category 5 for 10 Base T 10 Mbps Ethernet
or 10/100 switched Ethernet, fiber optic cabling, etc.)
Survey for a Small Area
To conduct a survey in a site where one or two access points are anticipated
- Document the size and layout of coverage area. Also,
document RF systems already in use, location of host system, and available
AC power.
- Set up an access point in the middle of the room or where
it is estimated that the coverage cell is the largest.
- Walk the perimeter of the coverage area and measure radio
coverage.
- For a wireless network, study round-trip ping times and data
rates. The individual round-trip ping time is usually about 7 ms before the rate
decreases when using a packet size of 1024 bytes.
- To display the number of packets transmitted and received and the rates for
each, click Test Totals on the Site Survey Tests dialog box.
- Move the mobile computer in different directions. Position the computer
between the surveyor and the access point. Do not walk fast. If you walk too
fast, you may miss coverage area
dead spots.
- Depending on the coverage requirements, you may have to determine the perimeter for each of the data
rates separately. For example, in a 2.4 GHz
environment, total test time should be less
than 13 seconds for 1 Mbit or 12 seconds for 2 Mbit.
- Mark the location of access points on the blueprint, move
the access point to the second survey location and repeat the procedure.
Infrastructure backbone, hubs and patch panels should all be documented.
Document the conditions existing in the final installation.
- Complete the Site Survey Report.
The report indicates the number and location of the access points. Assign
the access points the same channel for each coverage area.
Survey for a Medium or Large Area
To conduct a survey in a site where 10 or more access points are anticipated
- Document the size and layout of the coverage area. Also
document RF systems already in use, location of host systems, available AC
power, possible antenna locations, interfering metal fire breaks and wall
structures, doorways and passages that could help RF propagation, and amount
of stock in coverage areas. For a warehouse, document how high the stock is
kept and how high the lifts go so that the lifts do not damage the access
points.
- Set up an access point at one side of the proposed
coverage area.
- Walk the perimeter and measure radio coverage.
If there are multiple floors, measure each floor separately. For a wireless network, document round-trip times and data rates. The
individual round-trip ping time is usually about 7 ms before the rate
decreases when using a packet size of 1024 bytes. Move
the mobile computer in different directions. Position the computer between
the surveyor and the access point. Do not walk fast. If you walk too fast,
you may miss radio coverage dead
spots.
- Document the boundary of each coverage area. The data
rates could be different in each area. For results in better coverage, you
may only need to move the access point a
meter (three feet) or so. For higher data rate networks, reflection is a
bigger problem. Ceiling sprinklers can cause a problem if the access
point antenna is less than 60 centimeters (two feet) away. For example in a
2.4 GHz environment, total test time
should be less than 13 seconds for 1 Mbit or 12 seconds for 2 Mbit.
 |
NOTE: For
large surveys, consider the site survey boundary areas for multiple buildings.
Determine whether the network requires a LAN bridge, wireless access points or
both. |
- Mark the location of each access point on the blueprint
and move the access point to a different trial location.
Continue the process until the entire site has radio coverage.
- Take a photograph of at least one access point location for
each coverage area.
If each coverage area has unique features, take a picture of racks, stock
level and hub locations. The pictures go into the report and help establish
the condition of the site as it was surveyed.
- Consult with customer technical personnel and document
any additional hubs that could be required. Fourteen or more access points
could require multiple hubs.
Consider exact conditions that exist in the final installation.
- Complete the Site Survey Report.
The report indicates the number and location of the access points. Assign
the access points the same channel for each coverage area.
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