A while back I provided a client with a detailed design for a wireless solution and at the time a high focus was placed on the clients Skype for Business deployment. During my research I found Skype for Business over Aruba – Validated Reference Design and found the RF considerations below that can be used for any voice over wireless LAN (VoWLAN) solution. This should be helpful to site survey engineers or engineers troubleshooting voice issues.
- Power Settings – Transmit power values are 3, 6, 9, 12, 15, 18, 21, 24, 27, 30, 33, and 127 dbm. Consistent power levels will result in higher data rates. Minimum and maximum AP transmit power difference should not be more than two steps apart. For example, if the minimum transmit power is 9 dbm then the maximum transmit power should not exceed 15 dbm. AP power setting should use low to moderate power. For example, in a high density AP deployment set the minimum/maximum power should be 9 -12 dbm for 2.4 GHz and 12 -18 dbm for 5 GHz.
- Disable lower transmit data rates – If there are no 11b clients in the network, disable lower rates 1 – 11 Mbps.
- Set supported beacon rate to more than 12 Mbps – Beacons that are transmitted at the lowest basic rate, such as 1 Mbps, can consume a considerable amount of air time. Beacon rates should be set higher than 12 Mbps to avoid unnecessary consumption of bandwidth.
- Minimum RF signal (Received Signal Strength Indication (RSSI)) levels of -65 dbm in 2.4 and 5 GHz.
- Minimum Signal to Noise Ratio (SNR) of 25 dB – Higher signal level and high SNR are the indicators of a superior RF environment and will improve client transmission rates.
- Mitigate interference sources, such as microwave ovens, distributed antenna systems, and game consoles.
- Use 20 MHz channel bandwidth on 2.4 GHz.
- Use 40 MHz or less channel bandwidth on 5 GHz – It is recommended that high density deployments use 40 MHz or less channel bandwidth to reduce adjacent and co-channel interference. Using 80 MHz channel bandwidth in high density AP deployments may result in adjacent or co-channel interference.