Digital Signal Processing Reference
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Chapter 8
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In this final chapter of this topic, we first summarize its major conclusions. We intro-
duced design and operation approaches towards Smart(er) and Cognitive Software
Defined Radios, and showed its application in particular stringent cases. Conse-
quently and finally, we end this chapter and topic with some closing remarks. Many
open challenges still remain to realize the
Anything, Anytime, Anywhere
aspiration,
which definitely continues to be a moving target. Technological innovation is needed
to keep up the pace with increasing capacity requirements. Moreover, regulations,
economical and even social conditions have to be considered in order to ultimately
serve the users optimally.
8.1 “Good Enough” Is “Close Enough to Optimal”
Wireless services have attracted an impressively growing interest over the past
decades. This trend is expected to continue as ever more users want to exchange ever
more and richer information. Despite great progress in physical layer techniques, we
are however running out of wireless capacity. Novel solutions, both technological
and regulatory, are therefore needed to enable a sustainable growth in wireless com-
munication. This topic focuses on opportunities opened up by the progress towards
smart(er) and cognitive radios. In Sect.
8.2
of this chapter we draw the attention to
complementary tactics which we believe will also be vital to keep the communica-
tion going. The smart(er) and cognitive operation of radios presented in this topic,
exploit the possibilities offered by recent and emerging standards which enable a
more dynamic spectrum access (see Chap. 2). Consequently, radios that exploit
these new opportunities to adapt their behavior to the actual circumstances (both
in terms of service requirements and communication scenario) can achieve great
performance increase. We thereby adapt the taxonomy illustrated in Fig.
8.1
. While
cognitive radios can especially bring added value when they are built upon flexible
hardware (SDRs, reconfigurable radios), this is not the only form of flexibility to be
exploited in the wireless environment. Therefore, the case studies discussed in this
topic do not impose flexible hardware as a prerequisite.
