Securing Wireless Networks: A Checklist

When we are analyzing the locations of wireless routers, we can use different levels of receiving sensitivity and path loss to determine ideal mounting locations. Besides this, the distance of wireless networks with a lower frequency is always greater than the distance of wireless networks with higher networks.

Checklist (items included):

1. Introduction & Background 4. Results: Data, Tables, & Diagrams 2. Procedure 5. Analysis of Results 3. Troubleshooting & Testing 6. Conclusions Key Results:

According to this laboratory session, 2.4 GHz wireless network access points carry a higher range than 5 GHz. If access points of higher frequency are to be used, then a greater care is required compared to when using 2.4 GHz.

Key Conclusions (technical):

The 2.4 GHz connectivity has lower path loss than the 5 GHz because as the path loss increases with increase in frequency. Hence, 2.4 GHz shall be used to work between adjacent Access Points in any of the specified locations.

Key Conclusions (critical thinking):

From the data give in this lab session, it is important to understand how distance and frequency affect the successful communication of wireless devices. However, to compensate for a long distance we can leverage higher gain antennas on both the receiver and transmitter access points and devices.

Wireless Architecture

Introduction:

Objective: Using the provided manufacturer specification sheets, determine if two 802.11AC wireless routers will be able to communicate with each other in multiple locations, and if so, which antenna should be used and why. The table below shows the distances between router locations shown in the diagram.

Position 1 Position 2 Position 3 Position 4 Position 5

0 meters 120 meters 215 meters 215 meters 120 meters

0 meters 100 meters 160 meters 100 meters

0 meters 70 meters 100 meters

0 meters 90 meters

Preparatory Reading:

The following sections from the indicated texts or documents should be read before carrying out this lab:

Text: Chapter 5 Sections 5.2

Objective Achievement Steps:

Step 1: Below is the Cisco specifications manual link for an Aeronet Access Point, that includes the minimum receive level for an 802.11n (-75dBm is more received power than -90 dBm), identify the transmit (again using 802.11n output power (here, the greater the positive number, the greater the transmit power), and a list of compatible antennas. Use an antenna gain of 2 dBi (both transmit and receive), with a dipole radiation pattern, and 802.11n frequency range (both 2.5 GHz and 5 GHz). Ignore any transmission line loss. Assume that your system uses a Modulation and Coding Scheme #5 (MCS5) and transmits with an HT20 (4 antennas) at max power for 2.4 GHZ and HT40 (4 antennas) at max power for 5 GHz.

Provide separate results for the 2.4 GHz frequency and the 5 GHz frequency.

Table SEQ Table \* ARABIC 1

2.4 GHz // 802.11n (HT20) 5.0 HZ // 802.11n (HT40)

-90 dBm @ MCS0 -88 dBm @ MCS0

-90 dBm @ MCS1 -87 dBm @ MCS1

-90 dBm @ MCS2 -86 dBm @ MCS2

-88 dBm @MCS3 -82 dBm @ MCS3

-85 dBm @MCS4 -80 dBm @ MCS4

-80 dBm @MCS5 -75 dBm @ MCS5

-75 dBm @MCS6 -73 dBm @ MCS6

Table SEQ Table \* ARABIC 2

2.4 GHz // 802.11n (HT20) 5 GHz // 802.11n (HT40)

Maximum Transmit Power 23 dBm, 4 antennas 23 dBm, 4 antennas

Step 2: Using the presented building layout, the objective is to determine whether or not the link can be closed between two Access-Points (APs) identified in the specification sheet. The diagram shows the possible locations for the Wi-Fi Aps

8787963944678Meters x 10

00Meters x 10

Step 3: Using equation 5.4 in your text and assuming isotropic antennas in an obstructed factory (n=3), compute the path loss that will occur between the possible router positions. Add another column to the table above and list the path loss between each of the potential locations.

Table SEQ Table \* ARABIC 3

Path Distance 2.4 GHz Path Loss 5 GHz Path Loss

1 to 2 120 102.4 dB 108.8 dB

1 to 3 215 110.0 dB 116.4 dB

1 to 4 215 110.0 dB 116.4 dB

1 to 5 120 102.4 dB 108.8 dB

2 to 3 100 100.0 dB 106.4 dB

2 to 4 160 106.2 dB 112.5 dB

2 to 5 100 100.0 dB 106.5 dB

3 to 4 70 95.4 dB 101.8 dB

3 to 5 100 100.0 dB 106.4 dB

4 to 5 90 98.7 dB 105.0 dB

Step 4: Using the stock MIMO antenna (4 antennas) with 2 dBi gain, will all the APs be able to communicate directly? Calculate the receive signal level (RSL) between each of the potential locations. Create another table showing the RSL between each of the stations. Compare the RSL values with the minimum required power levels shown in the data sheet for each of the frequency ranges.

Table SEQ Table \* ARABIC 4

Path 2.4 GHz Path Loss 2.4 GHz RSL 5 GHz Path Loss 5 GHz RSL

1 to 2 102.4 dB -63.4 dB 108.8 dB -69.8 dB

1 to 3 110.0 dB -71.0 dB 116.4 dB -77.4 dB

1 to 4 110.0 dB -71.0 dB 116.4 dB -77.4 dB

1 to 5 102.4 dB -63.4 dB 108.8 dB -69.8 dB

2 to 3 100.0 dB -61.0 dB 106.4 dB -67.4 dB

2 to 4 106.2 dB -67.2 dB 112.5 dB -73.5 dB

2 to 5 100.0 dB -61.0 dB 106.5 dB -67.4 dB

3 to 4 95.4 dB -56.4 dB 101.8 dB -62.8 dB

3 to 5 100.0 dB -61.0 dB 106.4 dB -67.4 dB

4 to 5 98.7 dB -59.7 dB 105.0 dB -66.0 dB

Step 5: Compare the RSL values with the minimum required power levels shown in the data sheet. Create another table indicting whether the two APs will be able to communicate. If the links cannot be closed between two locations, identify which locations cannot communicate directly. Does it make a difference whether you are communicating at 2.4 GHz or 5 GHz? Explain.

Table SEQ Table \* ARABIC 5

Path 2.4 GHz RSL 2.4 GHz In Range 5 GHz RSL 5 GHz In Range

1 to 2 -63.4 dBm Yes -69.8 dBm Yes

1 to 3 -71.0 dBm Yes -77.4 dBm No

1 to 4 -71.0 dBm Yes -77.4 dBm No

1 to 5 -63.4 dBm Yes -69.8 dBm Yes

2 to 3 -61.0 dBm Yes -67.4 dBm Yes

2 to 4 -67.2 dBm Yes -73.5 dBm Yes

2 to 5 -61.0 dBm Yes -67.4 dBm Yes

3 to 4 -56.4 dBm Yes -62.8 dBm Yes

3 to 5 -61.0 dBm Yes -67.4 dBm Yes

4 to 5 -59.7 dBm Yes -66.0 dBm Yes

There are two links between APs that will not be able to communicate directly with each other, namely 1 to 3 and 1 to 4 on the 5GHz frequency. It does make a difference if you are communicating at 2.4GHz versus 5GHz, as the higher frequency of the 5GHz network will increase the path loss through a given distance.

Step 6: How much antenna gain is required to close the link between the router positions that currently cannot communicate. Is this a practical antenna?

There would have to be an antenna gain of 2.4 dBm in order to recompense for the path loss contribution of the 5GHz frequency between Aps 1 to 3 and 1 to 4. This could be a practical antenna as practical antennas are designed to work at a set frequency by design.

Step 7/conclusion: Complete a practical discussion on the extent of overhead/headroom that should be eliminated when designing real wireless systems. This should be an analysis that includes critical thinking about real world problems with simple models.

In the design of real wireless systems, there needs to stand a considerable amount of overhead or headroom left. In the case of real life systems, additional variables that we do not account for in this network could lead to additional signal loss between two Aps.