Wireless – Rukus wireless experiencing problem with DHCP

The better approach for deploying AP is a complete site survey to determine the AP density , multipath propagation characteristics, interference, noise etc.. before setting up the AP.

The first immediate checkpoint for the scenario in-hand should be checking of SNR, RSSI and operating frequency/co-channel interference.

For optimal performance, placement of AP plays a key role. AP should be located centrally within areas requiring coverage. Ensure to avoid coverage holes with proper overlapping of APs coverage areas. The radio range and data rate are inversely proportional. That is, the nearer the user to the AP, the higher the data rate(Due to reduced path loss and high SNR). For effective radio range, also ensure to avoid buildings in-between.

The type of antenna, its placement and antenna gain are crucial in deciding the maximum radio range and the coverage area. The range is directly proportional to antenna height, however if the height is beyond certain limit, interference can be more. An istropic antenna provides coverage area in the form a sphere. Dipole antenna provides coverage area in the form of doughnut. There are also various directional antennas. Beware that the omni-directional antenna can lead to hidden node problem incase of large cell size. Antenna with focused beam can be helpful. Multi-sector directional antenna can give high capacity, range.

Determine if there are other active channels in your environment that introduce interference. Presence of other APs operating in the same frequency in the same radio coverage area can cause interference. The operating channel and channel separation can also play a role in connection speed / call drops. You may need to change the channel/separation accordingly to reduce interference incase if there are only 802.11 devices. However it might not solve the problem incase of presence of interference from other non-802.11 technology devices (Bluetooth/Cordless phones etc..).

Also note that interference need not necessarily from another 802.11 devices, but also from other non-802.11 devices(Microwave oven, Cordless phones, Bluetooth devices...) that can cause secondary effects such that data rate gets reduced. The impact can be due to high output power and the time/frequency the signal is on. For example, Microwave ovens mostly operate in the same frequency band as 802.11b/g and hence are more likely to cause interference. It is better to keep away such devices(Microwave ovens,bluetooth, cordless phones etc...) from the coverage area or shield those devices to continue presence in the coverage area.

There is a typical tradeoff between capacity and coverage. The higher power level can increase the range but if there are nearby APs, it can lead to interference. If the capacity is of importance, it is better to have the APs closer together. However if the APs are closely placed, the proper level should be set to low to reduce co-channel interference. So, ensure to keep optimal power levels.

Above such points should be analyzed along with site survey and the collected data should be analyzed for optimal performance.

From your observations of high PER, suggest that transmission channel is impacted due to high interference / multipath fading/channel noise. A proper site survey can be very helpful to you.

The issue was to do with VLAN tagging. While I was tagging on the correct VLAN, the WAP didn't respond well to this. After a support call with Ruckus we decided to untag the VLAN on the WLAN the WAP provides. By setting the Access VLAN to 1 it makes no attempt to tag the traffic. Since the port to the Ruckus is already trunked to a specific VLAN this is fine for our network.

To fix this issue in the future using the same method do the following:

1. Log in to Zone Director
2. Click on "Configure" Tab
3. Click on "WLANs" on the left menu
4. Click "Edit" on the WLAN you want to provide to the WAP
5. Click "Advanced Options"
6. Set the "ACCESS VLAN" setting to "1" to untag