User's Manual

542 Bluetooth and Wireless Fidelity interference

interference that is on channel at 11 decibels (dB) less than the desired

signal. That is, the required signal-to-noise level is 11 dB.

For example, assume no loss exists in the antenna design, at 1 meter

away the power drops to -40 dBm. If the environment shows activity

throughout the band at -51dBm, performance of the Bluetooth headset

is optimal only within 1 meter of the IP Phone 1140E due to the

required Signal-to-Noise ratio of 11 dB. However, this calculation is

based on an ideal scenario.

•

Due to FCC regulations, Bluetooth is required to hop amongst at

least 40 of the 80 available channels in the 2.4 GHz band. Hence,

Bluetooth performance is optimized if approximately half of the 2.4 GHz

band possess low levels of WiFi activity. Low levels of WiFi activity

is determined by the desired performance versus distance of the

Bluetooth headsets.

Clients operate on the channels along with wireless access point (WAP).

Therefore, the interference zone can be up to twice the WAP range. The

interference levels subside on a per-channel basis only when a user

device is not nearby.

Nortel Communication Server 1000

IP Phones Fundamentals

NN43001-368 02.07

5 February 2009