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Wire and Wireless Communication Applications Chap. 8
Then, using Eq. (7–69), we see that the BER with fading and coding becomes
or one error every 78 s.
P e = QA12(19.10)B = 3.2 * 10 -10
SA8-3 BER for a Wireless Device Link Evaluate the BER of a wireless LAN (WLAN).
Assume that a portable computertelephonevideo terminal is connected to the outside world via
a wireless link within a building. The wireless link operates between the device and a base station
unit located within the building. The wireless link uses OOK signaling on a carrier frequency of
2.4 GHz, and the data rate is 2 Mbs. The device transmits power on the uplink is 0.5 mW. The
base station receiver has a noise figure of 8 dB and an IF bandwidth of 4 MHz. It incorporates an
envelope detector to detect the data. External noise at the receiver input is negligible when compared
with the internal noise of the receiver. Assume that the transmit and receive antennas are
simple dipoles; each has a gain of 2.15 dB. The path loss between the transmit and receive
antenna within the building environment is modeled by Eq. (8–47) as
L dB (d) = L FSdB (d 0 ) + 10n log a d d 0
b + X dB
(8–67)
where L dB (d) is the path loss in dB for a distance of d between the antennas, L FSdB (d 0 ) is the
free-space loss for a distance d 0 that is close to the transmitter, but in the far field, and d 7 d 0 .
n is the path loss exponent, and X dB represents the loss margin due to variations in the path loss
35
CNR at detector input of receiver
30
25
CNR (dB)
20
15
10
5
0
50
100 150 200 250 300 350 400 450 500
d (feet)
Figure 8–40 CNR for a wireless link. (Plot from SA8_3.m.)