Example 21.8
Consider the Bluetooth and IEEE 802.11 FH interference scenario (refer to Figure
21.20):
(a) Assuming that the acceptable error probability for the mobile terminal is
10
5
, fi nd (SIR)
min
that supports this error rate, and (b) using (SIR)
min
from
(a) calculate
r
max
for
d
10 m,
4,
P
BT
20 dBm and
P
AP
40 dBm
Solution
P
e
0.5
e
0.5
E
b
/N
0
10
5
0.
e
0.5
E
b
/N
0
E
b
N
0
21.6
13.35 dB
r
max
10
21.6
20
40
1
4
18.13 m
Example 21.9
Calculate
r
max
for the interference scenarios (see Figure 21.21) using
S
min
from
Example 21.8 and
d
10 m,
4,
P
BT
20 dBm and
P
MS
40 dBm
Solution
r
max
10
21.6
40
20
25.6 m
Example 21.10
Repeat Problems 21.8 and 21.9, if the IEEE 802.11 FH
device is replaced by the
IEEE 802.11 DS device (
G
p
11).
Solution
r
max
10
21.6
20
40
11
1/4
9.95 m
r
max
10
21.6
20
20
11
1/4
14.08 m
Note the interference ranges are smaller for the IEEE 802.11 DS device com-
pared to the IEEE 802.11 FH device.
21.14 IEEE
802.16
The IEEE 802.16 standard delivers performance comparable to traditional cable,
DSL, or T1 offerings. The principal advantages of systems based on 802.16 are
multifold: faster provisioning of service, even in areas that
are hard for wired infra-
structure to reach; lower installation cost; and ability to overcome the physical
limitations of the traditional wired infrastructure. 802.16
technology provides a
fl exible, cost-effective, standard-based means of fi lling gaps in broadband services
21.14 IEEE
802.16
765
Ch21-P373580.indd 765
5/3/07 10:58:46 PM
766
21 Wireless Local Area Networks
not envisioned in a wired world. For operators
and service providers, systems
built upon the 802.16 standard represent an easily deployable “third pipe” capa-
ble of delivering fl exible and affordable last-mile broadband access for millions of
subscribers in homes and businesses throughout the world [18,19].
The 802.16a is an extension of the 802.16 originally designed for 10–66 GHz.
It covers frequency bands between 2 and 11 GHz and enables non line-of-sight
(NLOS)
operation, making it an appropriate technology for last-mile applications
where obstacles such as trees and buildings often present and where base stations
may need to be unobtrusively mounted on the roofs of homes or buildings rather
than towers on mountains.
The 802.16a has a range of up to 30 miles with a typical cell radius of 4 to
6 miles. Within the typical cell radius NLOS performance and throughputs are
optimal.
In addition, the 802.16a provides an ideal wireless backhaul technology
to connect 802.11 WLAN and commercial 802.11 hotspots with the Internet.
Table 21.18 provides a road map of IEEE 802.16 standards.
Applications of the 802.16 are cellular backhaul, broadband on-demand,
residential
broadband, and best-connected wireless service (see Figure 21.22). The
802.16 delivers high throughput at long ranges with a high spectral effi ciency.
Dynamic adaptive modulation allows base stations to trade off throughput for
range. The 802.16 supports fl exible channel bandwidths to accommodate easy
cell planning in both licensed and unlicensed spectra worldwide. The 802.16
includes robust security features and QoS needed to support services that require
low latency, such as voice and video. The 802.16 voice
service can either be TDM
voice or voice over IP (VoIP). Privacy and encryption features are also included to
support secure transmission and data encryption.
The
worldwide interoperability for microaccess inc
. (WiMAX) forum, an
industry group, focused on creating system profi les and conformance programs
