Network coded cooperation in wireless networks [Elektronische Ressource] : theoretical analysis and performance evaluation / von Dereje Hailemariam Woldegebreal

Informations

• Publié par: universitat_paderborn
• Publié le: 01 janvier 2010
• Nombre de lectures: 56
• Langue: English
• Poids de l'ouvrage: 2 Mo

Extrait

FAKULTÄT FÜR
ELEKTROTECHNIK,
INFORMATIK UND
MATHEMATIK









Network-Coded Cooperation in Wireless
Networks: Theoretical Analysis and
Performance Evaluation



Zur Erlangung des akademischen Grades

DOKTORINGENIEUR (Dr.-Ing.)

der Fakultät für Elektrotechnik, Informatik und Mathematik
der Universität Paderborn
vorgelegte Dissertation
von

M.Sc. Dereje Hailemariam Woldegebreal
Paderborn



Referent: Prof. Dr.-Ing. Reinhold Häb-Umbach
Korreferent: Prof. Dr. rer. nat. Holger Karl


Tag der mündlichen Prüfung: 13.04.2010


Paderborn, den 23.04.2010
Diss. EIM-E/266

Acknowledgments
“Knowledge of what is possible is the beginning of happiness”
George Santayana
I would not have realized my PhD study dream without the financial support of the German
Academic Exchange Service (DAAD). I sincerely thank DAAD first. My deepest gratitude
goes to Prof. Dr. Holger Karl, head of the Computer Networks Research group, for his
support and trust from day one of my research. I enjoyed it very much to work under his
guidance and benefited a lot from his encouragements and meticulous way of thinking. It is
also an honor for me to be his second doctoral graduate.
Special thanks to Prof. Dr.-Ing. Reinhold Ha¨b-Umbach for being my examiner and going
through the thesis. I thank Prof. Dr. Marco Platzner for being supportive when I needed him.
I am so grateful for the constructive discussions and the work we have done together with
Stefan Valentin and Tobias Volkhausen. I also want to thank colleagues at the research group
for their assistance and creating a good working environment. In this regard, the credit goes
to Miss Tanja Langen and Hans-Joachim Kraus. I am indebted to my office mate Matthias
Andree for the good office atmosphere and being resourceful. I am happy for the chat and
friendly discussion with Hermann Simon Lichte, Christian Dannewitz, and Rana Azeem
M. Khan; Azeem, I will always remember those teatime talks. I should also acknowledge
Bernard Bauer from Paderborn Center for Parallel Computing for being collaborative when
he was needed. I appreciate the contribution from my compatriots Mekdes G. Girma and Dr.
Yohannes A. Demessie; their help usually comes in handy. I am thankful to my family for
their contribution in one or the other way, especially to Amarech and my mother. Finally,
I would like to thank my wife Kidist and my daughter Yanet for their unconditional love
and support. At times, the going was tough and I prevailed because of my wife; I love you
Kidist.
iiiAbstract
In today’s wireless networks, there is an increasing demand for high service quality, data
rates, and network coverage. However, when addressing these demands, noise, interference,
fading, power constraints, and bandwidth limitation are some of the fundamental challenges.
Spatialdiversity is one way to deal with these challenges and is achieved by sending and re-
ceiving a signal using multiple transmit and/or multiple receive antennas. The use of multiple
transmit and receive antennas in spatial diversity results in a technique called Multiple-Input
Multiple-Output (MIMO). In practice, however, one shortcoming of MIMO is that installing
multiple antennas per wireless node may not be feasible because of limitations in power,
cost, and/or device size.
When nodes are limited in the number of antennas, distributed nodes in the network can be
engaged to emulate MIMO. This technique of gaining spatial diversity is called cooperative
transmission. Information-theoretic studies have shown substantial capacity improvements
as compared to traditional point-to-point wireless networks. In recent years, network-coded
cooperation was proposed as one protocol to realize cooperation in wireless networks. Most
of the previous work done in this area considers error-free inter-user channels; however, this
is usually not the case in wireless networks.
This thesis investigates the performance of two types of network-coded cooperation pro-
tocols under a more practical scenario of erroneous wireless channels, transmissions using
orthogonal channels, and energy constraints. Specifically, we provide the analytical tools to
compute the error rate bounds of these two network-coded cooperation protocols, study their
outage behavior, and show that these protocols can achieve full diversity. We then investi-
gate the coverage area by using network-coded cooperation and study the effect of network
topology on outage performance. In large networks where a source has potential partners in
its surrounding to choose from, metrics that provide insight on how to select a partner are
required. One option would be to select a partner that minimizes the total energy spent in
the network. With energy minimization in mind, we finally analyze the energy consumption
of network-coded cooperation considering transmission, reception, and processing energy at
all cooperating nodes.
iiiivZusammenfassung
In heutigen drahtlosen Netzen wa¨chst die Anforderung an guter Servicequalita¨t, hohen Daten-
raten und umfassender Netzabdeckung sta¨ndig. Gleichzeitig gibt es jedoch Bandbreiten- und
¨ ¨Sendeleistungsbeschrankungen sowie Interferenz und Fading auf den drahtlosen Kanalen,
die das Erreichen dieser Anforderungen erschweren.
¨Kooperative Ubertragung ist ein neues Paradigma in der drahtlosen Kommunikation um
¨Kanal-Fading zu handhaben. Bei der kooperativen Ubertragung werden verteilte Knoten in
einem Netzwerk gruppiert und emulieren so Antennendiversita¨t. Informationstheoretische
Studien haben gezeigt, dass sich die Kapazita¨t im Vergleich zu herko¨mmlicher drahtloser
¨Punkt-zu-Punkt-Ubertragung verbessern la¨sst. In den vergangenen Jahren wurde “network-
coded” Kooperation vorgeschlagen und untersucht; ein Verfahren, bei dem Network Coding
¨in der kooperativen Ubertragung eingesetzt wird. In der Vergangenheit werden in der Lit-
eratur gro¨ßtenteils fehlerfreie Kana¨le zwischen den Nutzern angenommen. Dies ist jedoch
u¨blicherweise in drahtlosen Netzen nicht der Fall.
Diese Doktorarbeit untersucht die Performanceleistung zweier Typen von network-coded
Kooperationsverfahren in einem realita¨tsnahen Szenario mit Energiebeschra¨nkung bei fehler-
¨behafteter drahtloser Ubertragung u¨ber orthogonale Kana¨le. Konkret entwickeln wir ein
Framework, um die Outage Wahrscheinlichkeit der zwei network-coded Kooperationspro-
tokolle zu berechnen, ihr Outage Verhalten zu untersuchen und um zu zeigen, dass diese
Protokolle Diversita¨t ausnutzen ko¨nnen. Wir untersuchen, wie sich aufgrund von network-
coded Kooperation die abgedeckte Fla¨che erweitert und betrachten den Effekt der Netzw-
erktopologie auf die Outage Performance. Abschließend analysieren wir den Energiever-
brauch eines der network-coded Kooperationsverfahren unter Beru¨cksichtigung des indi-
viduellen Energieverbrauchs der Sende-, Empfang- und Verarbeitungsoperationen an allen
kooperierenden Knoten.
vviContents
1. Introduction 1
1.1. Review of Cooperative Transmission Protocols . . . . . . . . . . . . . . . 4
1.2. Network-Coded Cooperation . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.2.1. Review of network-coded cooperation . . . . . . . . . . . . . . . . 10
1.2.2. Literature survey on network-coded cooperation . . . . . . . . . . 13
1.3. Thesis Motivation and Contributions . . . . . . . . . . . . . . . . . . . . . 17
1.3.1. Thesis motivation . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1.3.2. Thesis contributions . . . . . . . . . . . . . . . . . . . . . . . . . 18
1.4. Organization of the Thesis . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2. Introduction to Network Coding 21
2.1. Network Coding in Error-Free Networks . . . . . . . . . . . . . . . . . . 21
2.2. Linear Network Coding . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
2.2.1. Encoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
2.2.2. Decoding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2.3. Network Coding and Channel Coding . . . . . . . . . . . . . . . . . . . . 27
2.3.1. Separate network-channel coding . . . . . . . . . . . . . . . . . . 28
2.3.2. Joint network-channel coding . . . . . . . . . . . . . . . . . . . . 29
2.4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3. Wireless Channels and Networks 31
3.1. System Model of the Point-to-Point Transmission . . . . . . . . . . . . . . 31
3.1.1. Forward error correction with channel coding . . . . . . . . . . . . 32
3.1.2. Modulation and demodulation . . . . . . . . . . . . . . . . . . . . 33
3.2. Wireless Channel Models . . . . . . . . . . . . . . . . . . . . . . . . . . 34
3.2.1. Noise and interference . . . . . . . . . . . . . . . . . . . . . . . . 34
3.2.2. Fading channels . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3.3. Information Theory – Fading Channel Capacity . . . . . . . . . . . . . . . 41
3.3.1. Capacity of Additive White Gaussian Noise Channel . . . . . . . . 42
3.3.2. Capacity of flat and slow fading channel