The Design of Cognitive MAC Protocols / Omar AbouBakr Mehanna

Supervisor: Ahmed Sultan

Thesis (M.A.)—Nile University, Egypt, 2009 .

"Includes bibliographical references"

Contents:
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 Overview of Related Work . . . . . . . . . . . . . . . . . . . . . . . 3
1.3 Network Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.4 Thesis Organization . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2. Spectrum Sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1 Spectrum Sensing Methods . . . . . . . . . . . . . . . . . . . . . . 7
2.2 Experimental Results using WARP . . . . . . . . . . . . . . . . . . 10
3. Slotted Primary Network . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.1 Full Sensing Capability: L = N . . . . . . . . . . . . . . . . . . . . 14
3.2 Limited Sensing Capability: L < N . . . . . . . . . . . . . . . . . . 21
3.3 Numerical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
ix
4. Un-slotted Primary Network . . . . . . . . . . . . . . . . . . . . . . . . . 32
4.1 Multiple Channel Access . . . . . . . . . . . . . . . . . . . . . . . . 32
4.2 Single Channel Access . . . . . . . . . . . . . . . . . . . . . . . . . 38
4.3 Numerical Results . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
5.1 Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
5.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Appendices:
A. Derivation of Whittle's Index . . . . . . . . . . . . . . . . . . . . . . . . 46
B. Derivation of ±1
i (t) and ±0
i (t) . . . . . . . . . . . . . . . . . . . . . . . . . 51
Bibliography . . .

Abstract:
The radio spectrum resource is of fundamental importance to wireless communica-
tion. Recent reports show that most available spectrum has been allocated. However,
most of licensed spectrum resources are under-utilized. This observation has encour-
aged the emergence of dynamic and opportunistic spectrum access concepts, where
secondary (unlicensed) users equipped with cognitive radios are allowed to opportunis-
tically access the spectrum as long as they do not interfere with primary (licensed)
users. To achieve this goal, the secondary users must monitor the primary tra±c in
order to identify spectrum holes or opportunities which can be exploited to transfer
data.
In this thesis, we consider the design of cognitive MAC protocols enabling a sec-
ondary transmitter-receiver pair to communicate over the idle periods of a set of
primary channels. More speci¯cally, we propose cognitive MAC protocols optimized
for both slotted and un-slotted primary networks. For the slotted structure, the ob-
jective is to maximize the secondary throughput while maintaining synchronization
between the secondary pair and not causing interference to the primary network. Our
investigations di®erentiate between two sensing scenarios. In the ¯rst, the secondary
transmitter is capable of sensing all the primary channels, whereas it senses only a
subset of the primary channels in the second scenario. In both cases, we propose
blind MAC protocols that e±ciently learn the statistics of the primary tra±c on-line
iv
and asymptotically achieve the throughput obtained when prior knowledge of pri-
mary tra±c statistics is available. For the un-slotted structure, the objective is to
maximize the secondary throughput while satisfying an interference constraint on the
primary network. Sensing-dependent periods are optimized for each primary channel
yielding a MAC protocol which outperforms previously proposed techniques that rely
on a single sensing period optimization.

Text in English, abstracts in English.