Enabling Sensing-based Opportunistic Spectrum Re-usage with Secondary QoS Support [Elektronische Ressource] / Daniel Willkomm. Betreuer: Adam Wolisz

Daniel Willkomm

Informations

• Publié par: technische_universitat_berlin
• Publié le: 01 janvier 2011
• Nombre de lectures: 9
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

Enabling Sensing-based
Opportunistic Spectrum Re-usage
with Secondary QoS Support
vorgelegt von
Diplom-Ingenieur
Daniel Willkomm
aus Berlin
von der Fakult at IV | Elektrotechnik und Informatik |
der Technischen Universit at Berlin
zur Erlangung des akademischen Grades
Doktor der Ingenieurwissenschaften
| Dr.-Ing. |
genehmigte Dissertation
Promotionsausschuss:
Vorsitzender: Prof. Dr. Hans-Ulrich Hei
Berichter: Prof. Dr.-Ing. Adam Wolisz
Berichter: Prof. Luiz DaSilva, Ph.D.
Tag der wissenschaftlichen Aussprache: 17. Mai 2011
Berlin 2011
D83iiAcknowledgments
Throughout the years this Ph.D. thesis has been written I was supported, guided, and ac-
companied by many people. Without all those people the project \Dr.-Ing. Willkomm"
would not have been possible.
First of all I would like to thank my advisor Prof. Wolisz for the guidance and
( nancial) support throughout all those years. Although it was often painful, I admire
his ability and mental exibility to always ask the right questions to improve and validate
my work. Next, I would like to thank my external examiner Prof. DaSilva, who was very
quick in reviewing my thesis, provided a lot of useful comments, and even escaped the
Queen in Dublin to come to Berlin for my defense on his birthday. Thanks Luiz!!!
Next on the list are my long-term colleagues and friends Zwilling Mati (a.k.a. Dr.
Bohge Bohge) and Sven (a.k.a. Swiety) for spending all this time with me at TKN
and the TU Berlin. Without you I probably would never have started my Ph.D. in
the rst place. To complete the group there is also Marc. Thanks guys for the fun
study times (especially the learning sessions) and | not to forget | also party times.
I would also like to thank Prof. Armin Zimmermann and all the Kollegiaten from the
DFG Graduiertenkolleg MAGSI, who always provided very valuable feedback on my
work. Thanks to Jean Bollot and Sridhar Machiraju from Sprint Labs in California
especially for the DySPAN best paper. I had a really fun time with you and learned a
lot. Thanks also to Ed for the support with all the administrative stu and for the great
Burrito place in San Bruno and to Jamie for the great cold-water diving in Monterey. I
have to thank all the TKN folks, especially oure assistants Petra, Heike,
and Sonja, who were always great help with everything that needed help and to our
technical sta Sven, Mali, George, and Peter. Furthermore, I’d like to thank the \old"
TKN folks, especially Prof. James Gro (a.k.a. Dr. Schnappi) for all the support in my
early Ph.D. years, Andy (especially for the green arrow bike trail), Mama Emma and
Ana (for bringing the \female touch" to the group). It was great to be able to begin my
Ph.D. in such a nice atmosphere where not always only working was important. I also
have to thank the \new" TKN folks for showing me that TKN can also be fun without
those \old" guys. I want to especially thank Luk asz, Micha, Filip, Thomas, Niels, Danil,
and Jan-Hinrich for reviewing my thesis on very short notice. Furthermore, thanks to
my students Christian, Mikolaj, and Michael for lots of fun doing research and to Karl
and Michael for the great work on the Mobility Framework and MiXiM.
iiiAcknowledgments
I also want to thank all my friends who supported me, especially Bijan (my oldest
friend who always has been there for me), Hannes (for many good WG parties), my
chica Kirsi and Nickoh (for Sommerrollen and Wizard), Mati (again) and Frauke, and
all the others I cannot name in person. Thanks also to all the guys making our San
Francisco time so much fun, especially Kevin, Thomas, Marije, Afshin, Martin, Kal,
Fidelma, and of course Mitch for the best SF apartment ever. Last but not least, a very
special thank you to all my family, especially my parents Elisabth and Horst and my
brothers and sisters Jonas, Judith, Simon, and Rahel. Without your love and support
nothing of this would have been possible. Finally, the biggest thanks has to go to my
wife Sandra and my little daughter-to-come Lina. Thanks for your love, support, and
understanding. And thanks to Lina for being patient enough and letting me nish my
thesis before seeing the light of day. Now I can hardly await you coming.
ivZusammenfassung
In den letzten Jahren wurde eine Diskrepanz zwischen den vergebenen Lizenzen fur Ra-
diospektrum und der tats achlichen Nutzung des Spektrums beobachtet. Obwohl die
ub erwiegende Anzahl von Frequenzb andern im fur drahtlose Kommunikation attrak-
tiven Spektrum lizenziert sind, wurde in vielen Messkampagnen gezeigt, dass gro e
Teile des Spektrums an vielen Orten tempor ar ungenutzt sind. Sensing basierte op-
portunistische Wiederverwendung von Spektrum ist ein interessanter Ansatz um diese
Diskrepanz zu beseitigen. In einem solchen Ansatz sensen sogenannte Sekund arnutzer
basierend auf Cognitive Radio (CR) Technologien die Frequenzb ander von lizenzierten
Prim arnutzern und benutzen das entdeckte, tempor ar ungenutzte Spektrum fur die
eigene Kommunikation. Die Au age fur eine solche Nutzung ist, dass das Spektrum
augenblicklich ger aumt werden muss sobald ein Prim arnutzer zuruc kkehrt. Eine o en-
sichtliche Herausforderung fur eine solche Art der Nutzung ist die zuverl assige Erken-
nung von Prim arnutzern. Die Sekund arnutzer mussen sicherstellen, dass das lizenzierte
Spektrum rechtzeitig ger aumt wird wenn n otig und dass keine fur den Prim arnutzer
sch adliche Interferenz entsteht. Fur solche CR Netzwerke ist allerdings nicht nur der
Schutz der Prim arkommunikation eine Herausforderung, sondern auch die Zusicherung
eines gewissen Quality of Service (QoS) fur die Sekund arkommunikation. Durch die
strikte Priorit at der Prim arnutzer muss die Sekund arkommunikation potentiell h au g
auf neue, tempor ar ungenutzte Frequenzen ausweichen. In dieser Arbeit pr asentieren
und evaluieren wir ein CR Systemdesign welches beide Herausforderungen adressiert.
Wir zeigen, dass das vorgeschlagene Design sowohl einen zuverl assigen Schutz fur den
Prim arnutzer als auch eine gewisse QoS Unterstutzung fur die Sekund arkommunikation
erreichen kann. Das Design kann dies sogar fur kleine Netzwerke mit wenigen, einfachen
Sekund arnutzern, welche einen auf Energiedetektion basierenden Sensing-Prozess fur die
Prim arnutzerentdeckung verwenden. Benutzt das Sekund arsystem eine gewisse Menge
an spektralem Overhead fur den Sensing-Prozess und die sekund are QoS Unterstutzung,
kann sogar in Szenarios mit hoher Variabilit at des tempor ar verfugbaren Spektrums
eine zuverl assige Prim arnutzererkennung und eine gewisse QoS Unterstutzung fur die
sekund are Kommunikation erm oglicht werden. Wir evaluieren den Tradeo zwischen
beiden Overheads und zeigen, dass es einen optimalen spektralen Overhead gibt, fur den
die spektrale E zienz maximiert wird. Wir zeigen weiterhin, dass, obwohl die spektrale
E zienz von anf anglich kleinen Netzwerken gering ist, sie trotzdem signi kant gr o er ist
vZusammenfassung
als Null. Des weiteren wird die spektrale E zienz mit wachsendem Sekund arnetzwerk
verbessert. Das macht unserer vorgeschlagenes CR Design zu einem idealen, skalierbaren
Ansatz fur initiale Netzwerkdeployments von kleinen und billigen CR Netzwerken: mit
steigender Netzwerkgr o e (welche normalerweise Hand in Hand geht mit einer steigenden
Kapazit atsnachfrage) steigt auch die spektrale E zienz.
viAbstract
Within the last years a discrepancy between the spectrum licenses and the actual usage
of spectrum has been observed. While the vast majority of frequency bands attractive
for wireless communication are licensed, measurement campaigns have shown that large
portions of the spectrum are temporarily unused in many locations. Sensing-based op-
portunistic spectrum re-usage has been identi ed as an attractive approach to overcome
this discrepancy. In this approach Cognitive Radio (CR) based Secondary Users (SUs)
sense the licensed frequency bands owned by Primary Users (PUs) for available spec-
trum and use the temporarily available spectrum on an opportunistic basis with the
constraint to vacate the spectrum as soon as the license holder returns. An apparent
challenge for such secondary spectrum usage is the reliable detection of the PU com-
munication. The SUs have to ensure that the licensed spectrum is always vacated in a
timely manner and that no harmful interference is created to the PUs. However, not
only the protection of the PU communication is a challenging task for such CR networks
but also the maintenance of a proper Quality of Service (QoS) for the secondary com-
munication. Due to the strict access priority of the PUs, the secondary communication
potentially has to be often relocated to new, temporarily available frequency bands. In
this thesis we present and evaluate a CR system design, which is able to cope with these
two challenges. We show that the proposed system design can achieve both reliable PU
protection and secondary QoS support even for small secondary networks consisting of
simple, low complexity CRs using energy detection-based spectrum sensing for the PU
protection. Using a proper amount of spectral overhead for spectrum sensing and for
secondary QoS support, reliable PU protection and secondary QoS support can also be
maintained in environments with very high variability of temporarily available spectrum.
We evaluate the tradeo b