21.13 Interference between Bluetooth and IEEE 802.11
Interference range is the distance between two devices in order to interfere, if
they operate at the same frequency and at the same time. The interference range
depends on propagation characteristics of the environment, processing gains of
receivers, and transmitted power from different devices. Figure 21.20 shows an
interference scenario between a transmitting Bluetooth (BT-1) device and a receiv-
ing IEEE 802.11 FH device (MS) collocated in the same area [15]. Since IEEE
802.11 AP is usually located on the wall to provide better coverage, it is less likely
to be interfered with by the BT. Interference occurs when the MS receives infor-
mation from the AP, and BT-1 transmits information to BT-2; or when the MS
transmits and BT-1 receives. We assume the interference from the AP to the BT
devices and the interference of the BT-2 to the IEEE 802.11 device are negligible.
When the MS is receiving and BT-1 is transmitting, the signal-to-interference ratio
(SIR) at the MS will be:
SIR
S
I
KP
AP
d
KP
BT
r
P
AP
P
BT
r
d
(21.8)
r
max
d
[(SIR)
min
(
P
BT
/P
AP
) ]
1/
(21.9)
where:
P
AP
and
P
BT
the transmitted power by the AP and Bluetooth devices, respectively
path loss exponent
d
distance between AP and IEEE 802.11 device
r
distance between Bluetooth device and IEEE 802.11 device
