27-11-2012, 11:54 AM
WiMAX TECHNOLOGY FOR BROADBAND WIRELESS ACCESS
[attachment=41276]
Introduction to Broadband
Wireless Access
The Need for Wireless Data Transmission
Since the fi nal decades of the twentieth century, data networks have known steadily growing
success. After the installation of fi xed Internet networks in many places all over the planet
and their now large expansion, the need is now becoming more important for wireless access.
There is no doubt that by the end of the fi rst decade of the twentieth century, high-speed wireless
data access, i.e. in Mb/s, will be largely deployed worldwide.
Wireless communication dates back to the end of the nineteenth century when the Maxwell
equations showed that the transmission of information could be achieved without the need for a
wire. A few years later, experimentations such as those of Marconi proved that wireless transmission
may be a reality and for rather long distances. Through the twentieth century, great electronic
and propagation discoveries and inventions gave way to many wireless transmission systems.
In the 1970s, the Bell Labs proposed the cellular concept, a magic idea that allowed the coverage
of a zone as large as needed using a fi xed frequency bandwidth. Since then, many wireless
technologies had large utilisation, the most successful until now being GSM, the Global
System for Mobile communication (previously Groupe Spécial Mobile), originally European
second generation cellular system. GSM is a technology mainly used for voice transmission in
addition to low-speed data transmission such as the Short Message Service (SMS).
Wireless Networks and Broadband Wireless Access (BWA)
Different Types of Data Networks
A large number of wireless transmission technologies exist, other systems still being under
design. These technologies can be distributed over different network families, based on a network
scale. In Figure 1.1, a now-classical representation (sometimes called the ‘eggs fi gure’)
is shown of wireless network categories, with the most famous technologies for each type of
network.
A Personal Area Network (PAN) is a (generally wireless) data network used for communication
among data devices close to one person. The scope of a PAN is then of the
order of a few metres, generally assumed to be less than 10 m, although some WPAN
technologies may have a greater reach. Examples of WPAN technologies are Bluetooth,
UWB and Zigbee.
A Local Area Network (LAN) is a data network used for communication among data devices:
computer, telephones, printer and personal digital assistants (PDAs). This network
covers a relatively small area, like a home, an offi ce or a small campus (or part of a campus).
The scope of a LAN is of the order of 100 metres. The most (by far) presently used LANs are
Ethernet (fi xed LAN) and WiFi (Wireless LAN, or WLAN).
Some IEEE 802 Data Network Standards
WiMAX is based on the IEEE 802.16 standard [1,2]. Standardisation efforts for local area
data networks started in 1979 in the IEEE, the Institute of Electrical and Electronics Engineers.
In February 1980 (80/2), the IEEE 802 working group (or committee) was founded,
dedicated to the defi nition of IEEE standards for LANs and MANs. The protocols and services
specifi ed in IEEE 802 map to the lower two layers (Data Link and Physical) of the
seven-layer OSI networking reference model [3,4]. IEEE 802 splits the OSI Data Link Layer
into two sublayers named Logical Link Control (LLC) and Media Access Control (MAC)
(see Chapter 3).
Applications of BWA
As already introduced above with IEEE 802.16, a BWA system is a high data rate (of the order
of Mb/s) WMAN or WWAN. A BWA system can be seen as an evolution of WLL systems
mainly featuring signifi cantly higher data rates. While WLL systems are mainly destined for
voice communications and low data rate (i.e. smaller than 50 kb/s), BWAs’ are intended to
deliver data fl ows in Mb/s (or a little lower).
The fi rst application of BWA is fi xed-position high data rate access. This access can then
evidently be used for Internet, TV and other expected high data rate applications such as
Video-on-Demand (VoD). It will also surely be used for other applications that are not really
apparent yet. In one word, the fi rst target of BWA is to be a wireless DSL (Digital Subscriber
Line, originally called the Digital Subscriber Loop) or also a wireless alternative for the
cable. Some business analysts consider that this type of BWA application is interesting only in
countries and regions having relatively underdeveloped telecommunications infrastructure.
Indeed, using WiMAX for the fi xed-position wireless Internet in Paris or New York does not
seem economically viable.
Another possible use of high data rate access with BWA is WiFi Backhauling. As shown in
Figure 1.4, the Internet so-called backbone is linked to a BS which may be in Line-of-Sight
(LOS) of another BS. This has a Non-Line-of-Sight (NLOS) coverage of Subscriber Stations
(SSs). The distinction between IEEE 802.16 NLOS and LOS technologies will be detailed in
Chapter 2.
Wireless is Not Mobile!
Different scenarios of mobility can be considered. The most simple one is when two neighbouring
BSs belong to the same operator. Hence, the same billing system and customer care
apply to the two BSs. In this case, a user moving from one cell to a neighbouring one has
to start the session again. This feature is nomadicity rather than mobility. Mobility (or full
mobility) is the scenario where the session is not interrupted, whether this is a data session, a
voice communication (over IP or not), a video transmission, etc.
Pre-WiMAX Systems
WiMAX and 802.16 systems will be described in detail in Chapter 2. In this subsection, the
pre-WiMAX is introduced. The fi rst version of the IEEE 802.16 standard appeared in 2001.
The fi rst complete version was published in 2004. There was evidently a need for wireless
broadband much before these dates. Many companies had wireless broadband equipment using
proprietary technology since the 1990s and even before. Evidently these products were
not interoperable.
With the arrival of the 802.16 standard, many of these products claimed to be based on it.
This was again not possible to verify as WiMAX/802.16 interoperability tests and plugfest
started in 2006. These products were then known as pre-WiMAX products. Pre-WiMAX
equipments were proposed by manufacturers often specialising in broadband wireless. Many
of them had important markets in Mexico, Central Europe, China, Lebanon and elsewhere.
Device prices were of the order of a few hundred euros. A nonexhaustive list of pre-WiMAX
manufacturers contains the following: Airspan, Alvarion, Aperto, Motorola, Navini, NextNet,
Proxim, Redline and SR Telecom. Intel and Sequans, among others, provide components.
[attachment=41276]
Introduction to Broadband
Wireless Access
The Need for Wireless Data Transmission
Since the fi nal decades of the twentieth century, data networks have known steadily growing
success. After the installation of fi xed Internet networks in many places all over the planet
and their now large expansion, the need is now becoming more important for wireless access.
There is no doubt that by the end of the fi rst decade of the twentieth century, high-speed wireless
data access, i.e. in Mb/s, will be largely deployed worldwide.
Wireless communication dates back to the end of the nineteenth century when the Maxwell
equations showed that the transmission of information could be achieved without the need for a
wire. A few years later, experimentations such as those of Marconi proved that wireless transmission
may be a reality and for rather long distances. Through the twentieth century, great electronic
and propagation discoveries and inventions gave way to many wireless transmission systems.
In the 1970s, the Bell Labs proposed the cellular concept, a magic idea that allowed the coverage
of a zone as large as needed using a fi xed frequency bandwidth. Since then, many wireless
technologies had large utilisation, the most successful until now being GSM, the Global
System for Mobile communication (previously Groupe Spécial Mobile), originally European
second generation cellular system. GSM is a technology mainly used for voice transmission in
addition to low-speed data transmission such as the Short Message Service (SMS).
Wireless Networks and Broadband Wireless Access (BWA)
Different Types of Data Networks
A large number of wireless transmission technologies exist, other systems still being under
design. These technologies can be distributed over different network families, based on a network
scale. In Figure 1.1, a now-classical representation (sometimes called the ‘eggs fi gure’)
is shown of wireless network categories, with the most famous technologies for each type of
network.
A Personal Area Network (PAN) is a (generally wireless) data network used for communication
among data devices close to one person. The scope of a PAN is then of the
order of a few metres, generally assumed to be less than 10 m, although some WPAN
technologies may have a greater reach. Examples of WPAN technologies are Bluetooth,
UWB and Zigbee.
A Local Area Network (LAN) is a data network used for communication among data devices:
computer, telephones, printer and personal digital assistants (PDAs). This network
covers a relatively small area, like a home, an offi ce or a small campus (or part of a campus).
The scope of a LAN is of the order of 100 metres. The most (by far) presently used LANs are
Ethernet (fi xed LAN) and WiFi (Wireless LAN, or WLAN).
Some IEEE 802 Data Network Standards
WiMAX is based on the IEEE 802.16 standard [1,2]. Standardisation efforts for local area
data networks started in 1979 in the IEEE, the Institute of Electrical and Electronics Engineers.
In February 1980 (80/2), the IEEE 802 working group (or committee) was founded,
dedicated to the defi nition of IEEE standards for LANs and MANs. The protocols and services
specifi ed in IEEE 802 map to the lower two layers (Data Link and Physical) of the
seven-layer OSI networking reference model [3,4]. IEEE 802 splits the OSI Data Link Layer
into two sublayers named Logical Link Control (LLC) and Media Access Control (MAC)
(see Chapter 3).
Applications of BWA
As already introduced above with IEEE 802.16, a BWA system is a high data rate (of the order
of Mb/s) WMAN or WWAN. A BWA system can be seen as an evolution of WLL systems
mainly featuring signifi cantly higher data rates. While WLL systems are mainly destined for
voice communications and low data rate (i.e. smaller than 50 kb/s), BWAs’ are intended to
deliver data fl ows in Mb/s (or a little lower).
The fi rst application of BWA is fi xed-position high data rate access. This access can then
evidently be used for Internet, TV and other expected high data rate applications such as
Video-on-Demand (VoD). It will also surely be used for other applications that are not really
apparent yet. In one word, the fi rst target of BWA is to be a wireless DSL (Digital Subscriber
Line, originally called the Digital Subscriber Loop) or also a wireless alternative for the
cable. Some business analysts consider that this type of BWA application is interesting only in
countries and regions having relatively underdeveloped telecommunications infrastructure.
Indeed, using WiMAX for the fi xed-position wireless Internet in Paris or New York does not
seem economically viable.
Another possible use of high data rate access with BWA is WiFi Backhauling. As shown in
Figure 1.4, the Internet so-called backbone is linked to a BS which may be in Line-of-Sight
(LOS) of another BS. This has a Non-Line-of-Sight (NLOS) coverage of Subscriber Stations
(SSs). The distinction between IEEE 802.16 NLOS and LOS technologies will be detailed in
Chapter 2.
Wireless is Not Mobile!
Different scenarios of mobility can be considered. The most simple one is when two neighbouring
BSs belong to the same operator. Hence, the same billing system and customer care
apply to the two BSs. In this case, a user moving from one cell to a neighbouring one has
to start the session again. This feature is nomadicity rather than mobility. Mobility (or full
mobility) is the scenario where the session is not interrupted, whether this is a data session, a
voice communication (over IP or not), a video transmission, etc.
Pre-WiMAX Systems
WiMAX and 802.16 systems will be described in detail in Chapter 2. In this subsection, the
pre-WiMAX is introduced. The fi rst version of the IEEE 802.16 standard appeared in 2001.
The fi rst complete version was published in 2004. There was evidently a need for wireless
broadband much before these dates. Many companies had wireless broadband equipment using
proprietary technology since the 1990s and even before. Evidently these products were
not interoperable.
With the arrival of the 802.16 standard, many of these products claimed to be based on it.
This was again not possible to verify as WiMAX/802.16 interoperability tests and plugfest
started in 2006. These products were then known as pre-WiMAX products. Pre-WiMAX
equipments were proposed by manufacturers often specialising in broadband wireless. Many
of them had important markets in Mexico, Central Europe, China, Lebanon and elsewhere.
Device prices were of the order of a few hundred euros. A nonexhaustive list of pre-WiMAX
manufacturers contains the following: Airspan, Alvarion, Aperto, Motorola, Navini, NextNet,
Proxim, Redline and SR Telecom. Intel and Sequans, among others, provide components.