Wireless metropolitan area networks (WirelessMANs) is emerging as a promising
broadband wireless access (BWA) technology to provide high-speed, high bandwidth
efficiency and high-capacity MultiMedia services for residential as well as enterprise
applications. It is observed that WirelessMAN (e.g., WiMAX) is even regarded as a 4G
technology. For the success of the WirelessMANs, international standardization organiza-
tions are very actively specifying the standards IEEE 802.16, ETSI HiperMAN and Korea
WiBro.
Mobile wireless communications are in constant evolution due to the continu-
ously increasing requirements and expectations of both users and operators.
Mass MultiMedia* services have been for a long time expected to generate a large
amount of data traffic in future wireless networks [1]. Mass MultiMedia services
are, by definition, purposed for many people. In general, it can be distinguished
between the distribution of any popular content over a wide area and the distribu-
tion of location-dependent information in highly populated areas. Representative
examples include the delivery of live video streaming content (like sports compe-
titions, concerts, or news) and file download (MultiMedia clips, digital newspa-
pers, or software updates).
Convergence between the two largest networks (Telecom and IP) is taking place
very rapidly and at diff erent levels: (1) network level: unifi cation of IP networks
with traditional Telecom networks through evolving standards (Session Initiation
Protocol (SIP), Realtime Transfer Protocol (RTP), SS7, 3G) to support interopera-
bility; (2) service level: traditional Telecom services like voice calls are being provi-
sioned on the IP backbone (VoIP), while traditional IP services (most data-driven
services such as MultiMedia, browsing, chatting, gaming, etc.) are accessible over
the Telecom network.
The use of mobile devices now surpasses that of traditional computers: wireless
users will hence soon be demanding the same rich MultiMedia services on their
mobile devices that they have on their desktop personal computers. In addition,
new services will be added, especially related with their mobile needs, such as
location-based information services.
When 3GPP started standardizing the IMS a few years ago, most analysts expected the
number of IMS deploymentsto grow dramatically as soon the initial IMS specifications were
ready (3GPP Release 5 was functionallyfrozenin the first half of 2002and completedshortly
after that). While those predictions have proven to be too aggressive owing to a number of
upheavals hitting the ICT (Information and Communications Technologies) sector, we are
now seeing more and more commercial IMS-based service offerings in the market. At the
time of writing (May 2008), there are over 30 commercial IMS networks running live traffic,
addingup to over10million IMS users aroundthe world; the IMS is beingdeployedglobally.
In addition, there are plenty of ongoing market activities; it is estimated that over 130 IMS
contracts have been awarded to all IMS manufacturers. The number of IMS users will grow
substantially as these awarded contracts are launched commercially. At the same time, the
number of IMS users in presently deployed networks is steadily increasing as new services
are introduced and operators running these networks migrate their non-IMS users to their
IMS networks.
The first practical examples of mobile communications were used in many countries like
the USA, the UK and Germany in military services, and played a significant role in the
First World War to transfer important information from the front to headquarters to take
further actions. Good and secure wireless communications were an important need for all
military services – army, navy and air force. In this respect, the Second World War was a big
experimental battlefield for the development and evolution of mobile radio. It was in the
interests of governments that after the Second World War the military investment should
be paid back by civilian use, and all western European countries started their so-called first
generation of mobile communication networks.
Fourth Generation (4G) wireless communication systems aim to allow peak data
rates in the range of 1 Gbps for nomadic access and 100 Mbps for vehicular mobil-
ity. 4G aims to support current and emergent MultiMedia services, such as mobile
TV, social networks and gaming, high-definition television and video telecon-
ference, MultiMedia messaging service, using the All-over IP concept and with
improved quality of service.
The continuing explosive growth in mobile communication is demanding more spectrally
efficient radio access technologies than the prevalent second generation (2G) systems such as
GSM to handle just the voice traffic. We are already witnessing high levels of mobile
penetration exceeding 70% in some countries. It is anticipated that by 2010 more than half of
all communications will be carried out by mobile cellular networks. On the other hand, the
information revolution and changing life habits are bringing the requirement of commu-
nicating on a MultiMedia level to the mobile environment. But the data handling capabilities
and flexibility of the 2G cellular systems are limited.
Digital radios have undergone an astonishing evolution in the last century. Born as a set of simple and
power-hungry electrical and electromechanical devices for low data rate transmission of telegraph data
in the Marconi age, they have transformed, thanks to substantial advances in electronic technology,
into a set of small, reliable and sophisticated integrated devices supporting broadband MultiMedia
communications. This, however, would not have been possible unless significant progress had been
made in recent decades in the field of signal processing algorithms for baseband and passband signals.
In fact, the core of any modern digital radio consists of a set of algorithms running over programmable
electronic hardware. This book stems from the research and teaching activities of its co-authors in
the field of algorithmic techniques for wireless communications. A huge body of technical literature
has accumulated in the last four decades in this area, and an extensive coverage of all its important
aspects in a single textbook is impossible. For this reason, we have selected a few important topics
and, for ease of reading, organized them into two parts.
Mobile radio communications are evolving from pure telephony systems to MultiMedia
platforms offering a variety of services ranging from simple file transfers and audio and
video streaming, to interactive applications and positioning tasks. Naturally, these services
have different constraints concerning data rate, delay, and reliability (quality-of-service
(QoS)). Hence, future mobile radio systems have to provide a large flexibility and scal-
ability to match these heterogeneous requirements.
