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Decentralized Ultra-Reliable Low-Latency Communications through Concurrent Cooperative Transmission

Klose, Robin (2023)
Decentralized Ultra-Reliable Low-Latency Communications through Concurrent Cooperative Transmission.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00024070
Ph.D. Thesis, Primary publication, Publisher's Version

Abstract

Emerging cyber-physical systems demand for communication technologies that enable seamless interactions between humans and physical objects in a shared environment. This thesis proposes decentralized URLLC (dURLLC) as a new communication paradigm that allows the nodes in a wireless multi-hop network (WMN) to disseminate data quickly, reliably and without using a centralized infrastructure. To enable the dURLLC paradigm, this thesis explores the practical feasibility of concurrent cooperative transmission (CCT) with orthogonal frequency-division multiplexing (OFDM). CCT allows for an efficient utilization of the medium by leveraging interference instead of trying to avoid collisions. CCT-based network flooding disseminates data in a WMN through a reception-triggered low-level medium access control (MAC). OFDM provides high data rates by using a large bandwidth, resulting in a short transmission duration for a given amount of data. This thesis explores CCT-based network flooding with the OFDM-based IEEE 802.11 Non-HT and HT physical layers (PHYs) to enable interactions with commercial devices. An analysis of CCT with the IEEE 802.11 Non-HT PHY investigates the combined effects of the phase offset (PO), the carrier frequency offset (CFO) and the time offset (TO) between concurrent transmitters, as well as the elapsed time. The analytical results of the decodability of a CCT are validated in simulations and in testbed experiments with Wireless Open Access Research Platform (WARP) v3 software-defined radios (SDRs). CCT with coherent interference (CI) is the primary approach of this thesis. Two prototypes for CCT with CI are presented that feature mechanisms for precise synchronization in time and frequency. One prototype is based on the WARP v3 and its IEEE 802.11 reference design, whereas the other prototype is created through firmware modifications of the Asus RT-AC86U wireless router. Both prototypes are employed in testbed experiments in which two groups of nodes generate successive CCTs in a ping-pong fashion to emulate flooding processes with a very large number of hops. The nodes stay synchronized in experiments with 10 000 successive CCTs for various modulation and coding scheme (MCS) indices and MAC service data unit (MSDU) sizes. The URLLC requirement of delivering a 32-byte MSDU with a reliability of 99.999 % and with a latency of 1 ms is assessed in experiments with 1 000 000 CCTs, while the reliability is approximated by means of the frame reception rate (FRR). An FRR of at least 99.999 % is achieved at PHY data rates of up to 48 Mbit/s under line-of-sight (LOS) conditions and at PHY data rates of up to 12 Mbit/s under non-line-of-sight (NLOS) conditions on a 20 MHz wide channel, while the latency per hop is 48.2 µs and 80.2 µs, respectively. With four multiple input multiple output (MIMO) spatial streams on a 40 MHz wide channel, a LOS receiver achieves an FRR of 99.5 % at a PHY data rate of 324 Mbit/s. For CCT with incoherent interference, this thesis proposes equalization with time-variant zero-forcing (TVZF) and presents a TVZF receiver for the IEEE 802.11 Non-HT PHY, achieving an FRR of up to 92 % for CCTs from three unsyntonized commercial devices. As CCT-based network flooding allows for an implicit time synchronization of all nodes, a reception-triggered low-level MAC and a reservation-based high-level MAC may in combination support various applications and scenarios under the dURLLC paradigm.

Item Type: Ph.D. Thesis
Erschienen: 2023
Creators: Klose, Robin
Type of entry: Primary publication
Title: Decentralized Ultra-Reliable Low-Latency Communications through Concurrent Cooperative Transmission
Language: English
Referees: Hollick, Prof. Dr. Matthias ; Gringoli, Prof. PhD Francesco
Date: 2023
Place of Publication: Darmstadt
Collation: xxvi, 253 Seiten
Refereed: 10 February 2023
DOI: 10.26083/tuprints-00024070
URL / URN: https://tuprints.ulb.tu-darmstadt.de/24070
Abstract:

Emerging cyber-physical systems demand for communication technologies that enable seamless interactions between humans and physical objects in a shared environment. This thesis proposes decentralized URLLC (dURLLC) as a new communication paradigm that allows the nodes in a wireless multi-hop network (WMN) to disseminate data quickly, reliably and without using a centralized infrastructure. To enable the dURLLC paradigm, this thesis explores the practical feasibility of concurrent cooperative transmission (CCT) with orthogonal frequency-division multiplexing (OFDM). CCT allows for an efficient utilization of the medium by leveraging interference instead of trying to avoid collisions. CCT-based network flooding disseminates data in a WMN through a reception-triggered low-level medium access control (MAC). OFDM provides high data rates by using a large bandwidth, resulting in a short transmission duration for a given amount of data. This thesis explores CCT-based network flooding with the OFDM-based IEEE 802.11 Non-HT and HT physical layers (PHYs) to enable interactions with commercial devices. An analysis of CCT with the IEEE 802.11 Non-HT PHY investigates the combined effects of the phase offset (PO), the carrier frequency offset (CFO) and the time offset (TO) between concurrent transmitters, as well as the elapsed time. The analytical results of the decodability of a CCT are validated in simulations and in testbed experiments with Wireless Open Access Research Platform (WARP) v3 software-defined radios (SDRs). CCT with coherent interference (CI) is the primary approach of this thesis. Two prototypes for CCT with CI are presented that feature mechanisms for precise synchronization in time and frequency. One prototype is based on the WARP v3 and its IEEE 802.11 reference design, whereas the other prototype is created through firmware modifications of the Asus RT-AC86U wireless router. Both prototypes are employed in testbed experiments in which two groups of nodes generate successive CCTs in a ping-pong fashion to emulate flooding processes with a very large number of hops. The nodes stay synchronized in experiments with 10 000 successive CCTs for various modulation and coding scheme (MCS) indices and MAC service data unit (MSDU) sizes. The URLLC requirement of delivering a 32-byte MSDU with a reliability of 99.999 % and with a latency of 1 ms is assessed in experiments with 1 000 000 CCTs, while the reliability is approximated by means of the frame reception rate (FRR). An FRR of at least 99.999 % is achieved at PHY data rates of up to 48 Mbit/s under line-of-sight (LOS) conditions and at PHY data rates of up to 12 Mbit/s under non-line-of-sight (NLOS) conditions on a 20 MHz wide channel, while the latency per hop is 48.2 µs and 80.2 µs, respectively. With four multiple input multiple output (MIMO) spatial streams on a 40 MHz wide channel, a LOS receiver achieves an FRR of 99.5 % at a PHY data rate of 324 Mbit/s. For CCT with incoherent interference, this thesis proposes equalization with time-variant zero-forcing (TVZF) and presents a TVZF receiver for the IEEE 802.11 Non-HT PHY, achieving an FRR of up to 92 % for CCTs from three unsyntonized commercial devices. As CCT-based network flooding allows for an implicit time synchronization of all nodes, a reception-triggered low-level MAC and a reservation-based high-level MAC may in combination support various applications and scenarios under the dURLLC paradigm.

Alternative Abstract:
Alternative abstract Language

Aufkommende cyber-physische Systeme verlangen nach Kommunikationstechnologien, die reibungslose Interaktionen zwischen Menschen und physischen Objekten in einer gemeinschaftlichen Umgebung ermöglichen. Diese Dissertation schlägt dezentralisiertes URLLC (dURLLC) als ein neues Kommunikationsparadigma vor, das es Knoten in einem drahtlosen Multi-Hop-Netzwerk (WMN) erlaubt, Daten schnell, zuverlässig und ohne zentralisierte Infrastruktur zu verbreiten. Um das dURLLC-Paradigma zu ermöglichen, erforscht diese Dissertation die praktische Umsetzbarkeit gleichzeitiger kooperativer Übertragungen (CCT) mit dem orthogonalen Frequenzmultiplexverfahren (OFDM). CCT erlaubt eine effiziente Nutzung des Mediums durch Ausnutzen von Interferenzen, statt Kollisionen möglichst zu vermeiden. CCT-basiertes Netzfluten verteilt Daten in einem WMN durch eine empfangsgetriggerte niedere Medienzugriffssteuerung (MAC). OFDM bietet hohe Datenraten durch die Nutzung einer großen Bandbreite und erzielt somit eine kurze Sendedauer für eine bestimmte Menge an Daten. Diese Dissertation untersucht CCT-basiertes Netzfluten mit den OFDM-basierten IEEE 802.11 Non-HT und HT Bitübertragungsschichten (PHYs), um Interaktionen mit kommerziellen Geräten zu ermöglichen. Eine Analyse zu CCT mit dem IEEE 802.11 Non-HT PHY untersucht die zusammenwirkenden Effekte des Phasenversatzes (PO), des Trägerfrequenzversatzes (CFO) und des Zeitversatzes (TO) zwischen gleichzeitigen Sendern, sowie der verstrichenen Zeit. Die analytischen Ergebnisse der Dekodierbarkeit von CCT werden durch Simulationen und Testbedexperimente mit softwaredefinierten Funksystemen (SDRs) der Wireless Open Access Research Platform (WARP) v3 validiert. CCT mit kohärenter Interferenz (CI) ist der primäre Ansatz dieser Dissertation. Es werden zwei Prototypen für CCT mit CI vorgestellt, die sich durch Mechanismen zur präzisen Frequenz- und Zeitsynchronisierung auszeichnen. Ein Prototyp basiert auf WARP v3 und dem zugehörigen IEEE 802.11 Referenzdesign, während der andere Prototyp durch Veränderungen der Firmware eines Asus RT-AC86U Drahtlosrouters erstellt wird. Beide Prototypen werden in Testbedexperimenten eingesetzt, in denen zwei Knotengruppen aufeinanderfolgende CCTs erzeugen, die sich gegenseitig auslösen, um Flutprozesse mit einer sehr großen Anzahl an Hops nachzuahmen. Die Knoten erhalten ihre Synchronisierung in Experimenten mit 10 000 aufeinanderfolgenden CCTs bei verschiedenen Indizes der Modulations- und Kodierverfahren (MCS) und Größen der MAC-Service-Dateneinheit (MSDU) aufrecht. Die URLLC-Anforderung, welcher zufolge eine MSDU mit 32 Bytes mit einer Zuverlässigkeit von 99,999 % und mit einer Latenz von 1 ms zu übermitteln ist, wird in Experimenten mit 1 000 000 CCTs geprüft, während die Zuverlässigkeit durch die Frame-Empfangsrate (FRR) angenähert wird. Bei 20 MHz Kanalbandbreite wird eine FRR von 99,999 % unter Sichtverbindung (LOS) bei PHY-Datenraten von bis zu 48 Mbit/s erzielt und ohne Sichtverbindung (NLOS) bei PHY-Datenraten von bis zu 12 Mbit/s, während die Latenz pro Hop jeweils 48,2 µs und 80,2 µs beträgt. Mit vier räumlichen Strömen via Multiple Input Multiple Output (MIMO) auf einem 40 MHz breiten Kanal erzielt ein LOS-Empfänger bei einer PHY-Datenrate von 324 Mbit/s eine FRR von 99,5 %. Für CCT mit inkohärenter Interferenz schlägt diese Dissertation die Entzerrung durch zeitvariantes Zero-Forcing (TVZF) vor und stellt einen TVZF-Empfänger für den IEEE 802.11 Non-HT PHY vor, der für CCTs von drei kommerziellen, nicht frequenzsynchronisierten Geräten eine FRR von bis zu 92 % erzielt. Da CCT-basiertes Netzfluten eine implizite Zeitsynchronisierung aller Knoten erlaubt, können ein empfangsgetriggerter niederer MAC und ein reservierungsbasierter höherer MAC in Kombination verschiedenartige Anwendungen und Szenarien unterstützen, die unter das dURLLC-Paradigma fallen.

German
Status: Publisher's Version
URN: urn:nbn:de:tuda-tuprints-240702
Classification DDC: 000 Generalities, computers, information > 004 Computer science
600 Technology, medicine, applied sciences > 621.3 Electrical engineering, electronics
Divisions: 20 Department of Computer Science
20 Department of Computer Science > Sichere Mobile Netze
TU-Projects: DFG|SFB1053|SFB1053 TPC01 Hollic
Date Deposited: 26 Jul 2023 12:14
Last Modified: 27 Jul 2023 08:05
PPN:
Referees: Hollick, Prof. Dr. Matthias ; Gringoli, Prof. PhD Francesco
Refereed / Verteidigung / mdl. Prüfung: 10 February 2023
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