Digital Signal Processing Reference
In-Depth Information
Chapter 1
Serving Many Mobile Users in Various
Scenarios: Radios to Go Smart(er)
and Cognitive
1.1 Towards Cognitive Radio
Anything, anytime, anywhere
! The holy grail of wireless communication is coming
closer. However, significant hurdles still need to be taken. Indeed,
Anytime
would
require the systems to have an infinite amount of energy resources, so as to guar-
antee an endless operation. Further,
Anything
implicitly means that the Quality of
Service (QoS) guarantees are as tough as they are diverse. Finally,
Anywhere
would
require the systems to be able to operate effectively in a broad range of heteroge-
neous environments.
The main difficulty behind the AAA paradigm lies in the scarcity of the used
resources. Thus, it is critical to share this resource efficiently and effectively. In
this topic, we focus on wireless spectrum and energy as scarce resources and which
are, hence, becoming expensive. Moreover, the increased flexibility in radio hard-
ware and wireless standards is both opening new opportunities and posing new chal-
lenges. As a result, radios need to evolve to smart and cognitive.
In this introductory chapter, we embark by highlighting how HardWare (HW)
implementation and policy guidelines are becoming increasingly flexible. We then
present the Cognitive Radio (CR) framework that implements the necessary control
functionality to harness this flexibility. The need for smart and cognitive radios is
explained, and the way forward as proposed in this topic is introduced.
1.2 Increasing the Hardware Flexibility
The current and emerging wireless telecommunication landscape is pushing for
more hardware flexibility. Software Defined Radios (SDRs) give an answer to this
need.
