Wireless Network-Coded Four-Way Relaying Using Latin Hyper-Cubes

This paper deals with physical layer network-coding for the four-way wireless relaying scenario where four nodes A, B, C and D wish to communicate their messages to all the other nodes with the help of the relay node R. The scheme given in the paper is based on the denoise-and-forward scheme proposed first by Popovski et al. Intending to minimize the number of channel uses, the protocol employs two phases: Multiple Access (MA) phase and Broadcast (BC) phase with each phase utilizing one channel use. This paper does the equivalent for the four-way relaying scenario as was done for the two-way relaying scenario by Koike-Akino et al., and for three-way relaying scenario in [3]. It is observed that adaptively changing the network coding map used at the relay according to the channel conditions greatly reduces the impact of multiple access interference which occurs at the relay during the MA phase. These network coding maps are so chosen so that they satisfy a requirement called exclusive law. We show that when the four users transmit points from the same M-PSK constellation, every such network coding map that satisfies the exclusive law can be represented by a 4-fold Latin Hyper-Cube of side M. The network code map used by the relay for the BC phase is explicitly obtained and is aimed at reducing the effect of interference at the MA stage.Comment: 14 pages, 6 figures, 2 tables. arXiv admin note: substantial text overlap with arXiv:1112.158

Wireless Network-Coded Three-Way Relaying Using Latin Cubes

The design of modulation schemes for the physical layer network-coded three-way wireless relaying scenario is considered. The protocol employs two phases: Multiple Access (MA) phase and Broadcast (BC) phase with each phase utilizing one channel use. For the two-way relaying scenario, it was observed by Koike-Akino et al. \cite{KPT}, that adaptively changing the network coding map used at the relay according to the channel conditions greatly reduces the impact of multiple access interference which occurs at the relay during the MA phase and all these network coding maps should satisfy a requirement called \textit{exclusive law}. This paper does the equivalent for the three-way relaying scenario. We show that when the three users transmit points from the same 4-PSK constellation, every such network coding map that satisfies the exclusive law can be represented by a Latin Cube of Second Order. The network code map used by the relay for the BC phase is explicitly obtained and is aimed at reducing the effect of interference at the MA stage.Comment: 13 Pages, 16 Figures. Some mistakes in the previous version have been fixe

Investigation on iterative multiuser detection physical layer network coding in two-way relay free-space optical links with turbulences and pointing errors

Physical layer network coding (PNC) improves the throughput in wireless networks by enabling two nodes to exchange information using a minimum number of time slots. The PNC technique is proposed for two-way relay channel free space optical (TWR-FSO) communications with the aim of maximizing the utilization of network resources. The multipair TWR-FSO is considered in this paper, where a single antenna on each pair seeks to communicate via a common receiver aperture at the relay. Therefore, chip interleaving is adopted as a technique to separate the different transmitted signals at the relay node to perform PNC mapping. Accordingly, this scheme relies on the iterative multiuser technique for detection of users at the receiver. The bit error rate (BER) performance of the proposed system is examined under the combined influences of atmospheric loss, turbulence-induced channel fading, and pointing errors (PEs). By adopting the joint PNC mapping with interleaving and multiuser detection techniques, the BER results show that the proposed scheme can achieve a significant performance improvement against the degrading effects of turbulences and PEs. It is also demonstrated that a larger number of simultaneous users can be supported with this new scheme in establishing a communication link between multiple pairs of nodes in two time slots, thereby improving the channel capacity

Physical-layer Network Coding for Cooperative Wireless Networks

As a newly-emerged paradigm in the networking techniques, physical-layer network coding (PNC) [1, 5] takes advantage of the superimposition of the electromagnetic waves, and embraces the interference which was typically deemed as harmful, by performing exclusive-or mapping. Therefore, the spectral efficiency is utilized, which in turn boosts the network throughput. In the classical 2-way relay channel (2-WRC), PNC only spends two channel uses for the bi-directional data exchange. However, one challenge for such a paradigm is that the singular fading states in the uplink of 2-WRC, might result in ambiguity for decoding the network coded symbol. One major focus of this thesis is to address the fading issue for PNC in the 2-WRC. Another fundamental challenge for PNC is to extend the PNC from the 2-WRC to a multi-user network such as the multi-way relay channel (M-WRC) or the hierarchical wireless network (HWN). To tackle these two fundamental challenges of PNC, several solutions are proposed in this thesis, which are summarized as follows: First, we introduce two efficient fading correction strategies, i.e., the rotationally-invariant coded modulation and the soft-bit correction. Second, a novel multilevel coded linear PNC scheme with extended mapping for the Rayleigh fading 2-WRC is proposed. Third, we design a new type of linear PNC for the Rayleigh fading 2-WRC, based on rings. We refer to such design as linear PNC over the hybrid finite ring. Fourth, we redesign PNC for the HWN, which facilitates the multi-user data exchange. To combat the co-channel interference introduced by multi-user data exchange, two efficient interference exploitation strategies based on network coding are proposed: 1) PNC with joint decoding; and 2) analogue network coding with interference-aware maximum likelihood detection. Finally, we propose a multilevel coded LPNC for the data exchange in the M-WRC

Energy efficient Routing Protocols for Underwater Acoustic Wireless Sensor Network

Technological advancement regarding oceanic world discovery and monitoring has led to autonomous communication, which results in the emergence of the Internet of underwater things (IoUT). Underwater acoustic wireless sensor networks have become one of the most recently researched within the IoUT. An underwater acoustic wireless sensor network consists of sensor nodes, autonomous vehicles, and remotely operated vehicles which are normally deployed to carry out a collaborative task within an underwater region. Underwater acoustic wireless sensor networks have become one of the most recently researched area which supports long transmission range. However, acoustic signals experience deformation due to factors which consist of noise, propagation delay, and low bandwidth. Sensor nodes are battery dependent which mean they are difficult to recharge or replace once deployed. Routing protocols play important role in the communication process between these sensor nodes. As a result, this research aims to develop an energy efficient routing protocol that can bring about optimal policies for energy consumption in the process of data aggregation and transmission. The developed routing protocol focused on sparse and dense network architectures by examining the popular ad-hoc routing protocol action on demand distance vector routing protocol (AODV) for sparse networks and low energy adaptive clustering hierarchy (LEACH) for dense network. For a sparse architecture this research identifies current energy and overhead challenges facing AODV which in turn modifies the protocol by creating a new energy aware and overhead friendly routing protocol called action on demand distance vector sparse underwater acoustic routing protocol (AODV-SUARP) for underwater communication. AODV-SUARP introduces the mechanism of route stability function (RSF) by colour mode to select the most energy efficient route to forwards packets. For dense architecture this research identifies the energy challenge facing the conventional LEACH routing protocol which in turn leads to its modification by creating a new energy aware routing protocol called low energy adaptive clustering hierarchy dense underwater acoustic routing protocol (LEACH-DUARP). Furthermore, for the optimal selection of eligible cluster head in a subsequent round LEACH-DUARP introduces a concept called the stability function value (SFV). The developed routing protocols (AODV-SUARP and LEACH-DUARP) were implemented in NS-3 and validated using mathematical modelling. Results obtained indicated both AODV-SUARP and LEACH-DUARP achieves a considerable result compared to other routing protocols in terms of residual energy, packet delivery ratio, and number of dead nodes

The development of digital technologies for use in jewellery with medical applications

If medical products were to possess the qualities of ‘desirability’ that are commonly associated with jewellery, positive user interaction would be enhanced. The wearer would be able to use medical products with pleasure and confidence, without fear or social stigma, and in doing so retain an element of personal control which might otherwise be lost to them. This research addresses intersections between the two disciplines of craft and science of medicine. It focuses on developing new digital jewellery capable of monitoring the medical parameters of a patient as well as redeveloping specific products such as the Asthma Inhaler, the Diabetic Insulin-Pen, and the Human Immunodeficiency Virus Medication Carrier. The aim in each case was to produce a more effective and user-friendly set of items. This research also facilitates the categorisation of jewellery artefacts which have a medical purpose, evaluating the benefits of devising new designs to ameliorate known problems, such as, iatrophobia (a phobia of seeking medical advice from a doctor or medical expert), or sociophobia (fear of being negatively judged in social situations)

Actress Hedy Lamarr, Inventor: A Public Image Reframed

Hedy Lamarr, billed as “The Most Beautiful Woman in the World,” was a prominent American movie star in the 1940s and 50s. She was part of the “studio system” of Hollywood, where the early movie studios controlled actors’ salaries and hours, which films they acted in, their publicity and public-facing personas, including through contractual morality clauses regarding their personal lives. Lamarr’s beauty was her defining characteristic in Hollywood marketing schemes, but she was more than a beautiful face. She was an inventor. Today, Hedy Lamarr is credited with inventing “frequency hopping,” a foundational concept in modern digital communications which includes cellular, satellite, secure Wi-Fi, and Bluetooth signal processing. In short, she was a pioneer in the development of a technology that has changed the world. This is a remarkable innovation from someone dismissed at the time for being so beautiful that she could not possibly have a brain. Due to her beauty, Lamarr seldom received credit for having any kind of skill, including within the profession of acting. Although there was very little contemporary news coverage of her invention, forty-years later (in the 1980s), the story of Lamarr as inventor began to spread via internet newsgroups, completely reframing frequency hopping as a brilliant scientific invention by a woman never given proper credit for her contributions and in lament of her lost potential. Only with the advent of the internet (which evolved from her patent) as the primary vehicle for her story, did this shift in Lamarr’s public image emerge. In my thesis, I will use critical feminist discourse analysis to unpack the story of Actress Hedy Lamarr, Inventor, to illuminate the prevailing intersectional discourses and structural barriers impacting women and other minoritized groups in Science, Technology, Engineering, and Mathematics (STEM) and other male-dominated professional fields, to the present day