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Wireless Local Area Networks
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| bet | 20/55 | | Sana | 24.05.2024 | | Hajmi | 343,31 Kb. | | #252539 |
Bog'liq garg2007Example 21.4
A WLAN is required to have the minimum
E
b
/
N
0
of 10 dB in an indoor offi ce
environment. The background noise at 2.4 GHz is
120 dBM. If the transmit
power is 20 mW and there is no line-of-sight (NLOS) between the AP and mobile
terminals, what is the coverage of the AP? Assume a data rate of 1 Mbps and
channel bandwidth of 0.5 MHz. Use the joint technical commitee (JTC) path loss
model in which for NLOS conditions in the indoor offi ce environment, path loss
at the fi rst meter (
A
) is 37.7 dB and path loss exponent,
,
is 3.3. Assume power
loss from the fl oors to be 19 dB and a shadow effect of 10 dB.
Solution
Required
S
N
E
b
N
0
R
B
w
10
1
0.5
20 dB
Transmit power
10 log 20
13 dBm
Receiver sensitivity
120
20
100 dBm
Maximum allowable path loss
13
(
100)
113 dB
L
p
A
10
log
d
L
f
(
n
)
X
where:
A
path loss at the fi rst meter
path loss exponent
L
f
function relating power loss with number of fl oors,
n
X
lognormally distributed random variable representing the shadow effect
d
distance between AP and mobile terminal
113
37.7
33 log
d
19
10
d
25.3 meters
21.5.3 IEEE 802.11 Data Link Layer
The data link layer within 802.11 consists of two sublayers: logical link con-
trol (LLC) and media access control (MAC). 802.11 uses the same 802.2 LLC
and 48-bit addressing as the other 802 LAN, allowing for simple bridging from
wireless to IEEE wired networks, but the MAC is unique to WLAN. The sublayer
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