Wireless Site Survey
Call eTribeca at 888-219-0207 or e-mail us at sales@etribeca.com to discuss and schedule wireless site surveys.  We perform surveys both for end-users and as sub-contractors to other organizations.  We cover Domestic US.

The Importance of a Site Survey
For radio LAN’s it is very important to perform a site-survey to determine the effects of the facility on the propagated of radio waves.  This makes it possible to calculate the number of wireless Access Points needed, as multiple cells will be necessary in a large building.  It is also important to test that there is no interference that may present at some locations that may make the wireless network inoperable.
Part of the wireless network design is to identify the location of these Access Points to provide an interface to network resources located on the wired network and adequate coverage for roaming users throughout the facility.

If a wireless network were deployed in a completely open area, free from walls, building components and furniture, radio waves from the wireless devices would be able to maintain an omni directional radiation pattern, making it simpler to predict the maximum operating range among all devices and the location of the Access Points.  The construction of the facility offers radio waves through flooring, for example, depends on the building methods present between the floors.  Range is greatest if passing through plywood, fair if passing through concrete, and very poor if going through metal.

eTribeca’s engineers will conduct a detailed site survey of the building in preparation for deployment of the wireless Ethernet equipment.  The only true method for optimum site performance is to test empirically for proper placement of Access Points and type of antenna to be employed.  There is no way to determine the distance that a signal will travel without a survey.  Metal film on glass, leaded glass, steel studded walls, cement floors and walls with steel reinforcement, foil backed insulated walls, firewalls stairwells and elevator shafts are typical items that will reduce range.  In a multi floor building, it is necessary to do a three dimensional profile.

We shall require a layout plan of the building for marking up.  If there is none available, eTribeca LLC will create one.

Site Survey Methodology

A. Overview of a Wireless Site Survey

To simulate the operation of the wireless network as closely to future operating conditions as possible, we will use two Cisco Aironet 802.11b Access Points mounted at different locations, and two laptop computer systems equipped with Cisco Aironet 802.11b series wireless LAN cards, which can be used to roam throughout the facility. Theses tests will be performed 1) to demonstrate the technology and 2) to determine the area covered and quality of Wireless Connectivity. Both the wireless cards and the 802.11b Access Points run at 11Mbps. Our engineers have experience with using  AirMagnet for site surveys as well as Cisco.

The basic antenna that will be used is a 2.2dBi Dipole. If the topology of the building demands it, we shall also survey with 3 dBi Omni or 8.5dBi patch antennae, or such other antennae as our engineers consider to be appropriate when they are on site.
The test applications that will be used are “PING” and Cisco Aironet “Site Survey Utility” software. By varying the PING arguments (the number of times to PING), we are able to monitor the connectivity of the wireless link.

PING Test: Each laptop continuously PINGs two Access Points. The tester records statistics on the minimum round-trip time, maximum round-trip time, average round-trip time and percentage of no-response (packet losses).
 
Redundancy Test: Redundancy between Access Points is tested utilizing “Site Survey Utility”, a testing application from Cisco Aironet. This test shows the signal strength and quality from the Wireless LAN Adapter to each Access Point.
 
Load test: In this test, creating a peer-to-peer environment simulates a LAN environment between two computers, and file transfers are performed between the two. This demonstrates the relationship between bandwidth and distance in the wireless infrastructure.
 
B. Explanation of PING test

PING is a utility used to perform a connectivity test in a TCP/IP network. PING works at the network layer. The protocol utilized is ICMP (Internet Control Message Protocol), which is in the same layer as IP (Internet Protocol). The program transmits a predetermined Ethernet packet size to a destination host, which is returned to the originating computer. PING reports the round-trip time of the packet. By default, PING sends out four requests and reports the statistics in the form of a maximum, minimum, and average round-trip time. If there is no response within certain
 
A typical PING test reply looks like the following:

Pinging 209.14.129.1 with 500 bytes of data:
Reply from 209.14.129.1: bytes=500 time=12ms TTL=128
Reply from 209.14.129.1: bytes=500 time=12ms TTL=128
Reply from 209.14.129.1: bytes=500 time=14ms TTL=128
. . . (omitted 94 lines, total 100 lines) . . .
Reply from 209.14.129.1: bytes=500 time=16ms TTL=128
Reply from 209.14.129.1: bytes=500 time=13ms TTL=128
Reply from 209.14.129.1: bytes=500 time=16ms TTL=128
Ping statistics for 209.14.129.1:
Packets: Sent = 100, Received = 100, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 11ms, Maximum = 62ms, Average = 15ms
 

C. Explanation of Cisco Aironet Site Survey Utility

This Utility shows the status of the access point to which the client adapter is associated.

Access Point

The access point to which the client adapter is associated. This field may show the access point's name, IP address, and MAC address.

Channel

The channel number and radio frequency that the access point is currently using for communications.

Signal Strength

The current signal strength of the most recently received packets. Differences in signal strength are indicated by the following colors: green (strongest), yellow (middle of the range), and red (weakest).

Noise Level

The level of background radio frequency energy. Differences in background noise are indicated by the following colors: green (low noise), yellow (middle of the range), and red (high noise).

 Signal Quality

The current signal quality of the most recently received packets. Differences in signal quality are indicated by the following colors: green (highest quality), yellow (average), and red (lowest quality).

Beacons Received

The percentage of beacon packets received from the access point versus those expected to be received.

Signal-to-Noise Ratio
The difference between the signal strength and the noise level.

Overall Link Quality

A combination of signal strength and signal quality. Differences in quality are indicated by the following colors: green (highest quality), yellow (average), and red (lowest quality).
Possible Values: Poor, Fair, Good, or Excellent; 0 to 100%

Link Speed

The site survey utility monitors transmitted network traffic, and the link speed reflects the current transmit rate of data packets. Differences in link speed are indicated by the following colors: green (fastest), yellow (middle of the range), and red (slowest).
Possible Values: 1, 2, 5.5, 6, 9, 11, 12, 18, 24, 36, 48, or 54 Mbps, depending on radio band

Call eTribeca at 888-219-0207 or e-mail us at sales@etribeca.com to discuss and schedule wireless site surveys.  We perform surveys both for end-users and as sub-contractors to other organizations.  We cover Domestic US.