introduces WIMAX principle and its applications within the military

1. WIMAX
WORLDWIDE INTEROPERABILITY FOR
MICROWAVE ACCESS
Souheil Ben Tekaya

2. Introduction




802.16 as a standard
WiMAX as a marketing term
WiMAX forum, 802.16 working group
History:
 90s,
standard missing,
 IEEE first version of the standard in 2001


3. Plan





Definition
Techniques
Topology
Military Applications
Advantages and drawbacks

4. Definition


WiMAX forum develops guideline aka profiles
First two commercialized versions: d (2004)
and e(2005), define
 PHY
and MAC layers
 Frequency below 11 GHz
 Version d: fixed services
 Version e: mobile services

5. 802.16 technology
specifications
Specificati
on
Year of
ratification
Description
802.16
2001
802.16a
2003
MAC and PHY definition for fixed broadband wireless access in the 10-66
GHz bands
Contains new PHY definitions for the 2-11 GHz bands. Also includes mesh
network modes of operation
802.16c
2002
System profiles for 10-66 GHz operations
802.16d
2004
Contains 802.16, 802.16a, and various MAC enhancements. Known as
802.16-2004,
considered the base fixed broadband wireless specification
802.16e
2005
Amendment to the 802.16d specification, explicit support for mobility.
802.16f
2005
802.16 Management Information Base (MIB)
802.16g
2007
Network Management (management plane control procedures)
802.16h
2010
Coexistence in license exempt frequency bands
802.20
In progress
Mobile broadband wireless access standards group. Initially formed as a
study group
Within the 802.16 working group focused solely on mobility, supporting
train-like speeds.

6. Techniques

Duplexing:
 Time-Division
Duplexing:
 Wireless
medium divided in time,
 separate periods of time allocated for Uplink Channel
and Downlink Channel
 Single frequency channel used
 Half-duplex
 Frequency-Division
 UC
Duplexing:
and DC separated in frequency
 Full-duplex and half-duplex
 Pro: Use of different modulation types
 Con: Static assignment of UL and DL  Less flexible
than TDD

7. Techniques (PHY)

FDM: is a special form of Multi-carrier Modulation
transmission technique.
 MCM:
sub-carrier separated by guard band, No overlap
 Badpass
filters in receiver to separate the spectrum of sub-
carriers
 OFDM:
employs densely spaced orthogonal subcarriers and overlapping spectrum no bandwidth filter
required.

8. Technique

Modulation: 802.16a/d defines 7 combinations
of modulation and coding rates (trade-offs of
data rate and robustness)
Quadrature phase-
0
BPSK
1/2
0.5
Peak data rate
in 5 MHz
(Mb/s
)
1.89
shift keying (QPSK)

1
QPSK
1/2
1
3.95
2
QPSK
3/4
1.5
6.00
3
16QAM
1/2
2
8.06
4
16QAM
3/4
3
12.18
5
64QAM
2/3
4
16.30
6
64QAM
3/4
4.5
18.36
Binary phase-shift
keying (BPSK)


Quadrature amplitude
modulation (QAM)
Rate
ID
Modulatio
n rate
Codin
g
Information
bits/symbol

9. Technique




Coding: Adaptive Modulation and Coding (AMC)
is the standard approach in WiMAX standards.
Dynamically adapt the modulation and coding
scheme to the channel conditions highest
spectral efficiency.
802.16 uses Reed-Solomon block code+ inner
convolutional code.
Turbo code(optional feature):improve
coverage/capacity, at the price of increasing
decoding latency and complexity.

10. Topology


PMP: point to multi-point (Base Station, Subscriber’s
Stations)
Mesh : Subscriber Stations serve as routers to
enable multi-hop routes.
 Pro:
coverage
 Con: less throughput

11. Military Applications


Jamming resistant (mesh topology), new routes
Power amplifier: NATO Band I (225 to 400 MHz) has
tested under 802.16 OFDM 64QAM modulation, the
average output power is 25 W throughout the bandwidth


Works in high frequency Doesn’t disturb other
freq. ranges
2 scenarios:
Border surveillance using cameras installed on the
WiMAX towers
 Communication between ship to share SATCOM with
HQ  cost effective.
 Rescue operation: replace wired connections
destroyed amid disasters


12. Advantages


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Mesh topology: larger range, and jam resistant
Strong QoS, good bandwidth efficiency (thanks to
AMC)
Flexible architecture
Non-LOS connection (using OFDM ), can be
improved using directional antennas

13. Drawbacks



Limited Mobility: up to 145 km/h for 802.16e
802.20: support up to 240 km/h, allows it to be
implemented in relatively fast vehicles such as
UAVs….
still cannot reach weapons or aircraft range.