Different radio signals and other wireless networks could interference with yours WLAN signal. This could cause decrease in radio coverage. Different obstacles especially steel reinforcing could even cause complete loss of signal called black spot.



Radio Coverage of one access point (BSS) is often not enough for many situations.

There are available different methods for extension of WLAN radio coverage:

1) Use access point in repeater mode - wireless distribution system. When you use wireless distribution system or access point in repeater mode, AP is not connected to backbone. Its connection to backbone is over root access point. Its Ethernet port is connected to backbone. In repeater mode, Ethernet port on the AP does not forward traffic.

So you have repeater AP, connected to root AP, and if client connects to repeater AP, range is extended.

Repeater mode disadvantage is decrease in bandwidth - because AP needs to receive and send packet on the same channel.

2) Increase power level of access point. You can extend radio coverage area of access point by increasing AP power level. Transmitted power of access point is directly proportional to the radio coverage area. So if you increase power, radio coverage area will be larger.

Government regulates the highest power level for radio devices. Maximum power level is 100 mW. Usually power on access point is reduced, because of interference. If you make proper site survey, you can use maximum possible transmitted power.

Here is procedure to set up optimal power level on AP:

- Set maximum power on AP.

- Decrease power on AP until you get high and consistent bandwidth

You could also start from lowest possible power level. Then you increase power level until you get maximum and consistent bandwidth.

3) Distribute access points optimally. You can increase radio coverage area by doing proper site survey. Distribution of access points is very important factor of the radio coverage area.

You’ll be amazed, but to many access points can reduce bandwidth. They can make congestion and interference.

If you want to make maximum radio coverage, position access points to have 15 % overlap between. You can cover very large area with minimum cost, if you distribute access points with minimum overlap. Stations can move freely and make roaming between access points, if you put same SSID on all access points in area.

Make proper planning, and right access point distribution, and you will with minimum coast have optimal results.

4) Use of secondary access point with non-overlapping channels. Use of secondary AP in access point mode with non-overlapping channels, can make your radio coverage much larger.

Use this method only if you can connect this second access point to backbone, or wired part of the network. Disadvantage of this method is that wired network has to be reachable to second access point.

Advantage of this method is, that it is easiest to implement. It doesn’t require much of configuration. Just a basic configuration on second access point.

Use non-overlapping channels, when you configure this 2 access points. If you use close, overlapping channels, interference could happen. This leads to poor connectivity and lower bandwidth.

Make sure to have just right distance between to access points. If they are to close, you can have congestion, and you are also loosing radio coverage area.

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