Cooperative diversity exploits the broadcast nature of wireless channels and uses relays to improve link reliability. Most cooperative communication protocols are assumed to be synchronous in nature, which is not always possible in wireless communication. Also the relay nodes are assumed to be half duplex which in turn reduces the spectral efficiency. In this thesis, we first present a novel asynchronous cooperative communication protocol exploiting polarization diversity, which does not require synchronization at the relay node. Dual polarized antennas are employed at the relay node to achieve full duplex amplify-and-forward (ANF) communication. Hence the transmission duration is reduced which results into an increased throughput rate. Capacity analysis of the proposed scheme ascertains the high data rate as compared to conventional ANF. Bit error rate (BER) simulation also shows that the proposed scheme significantly outperforms both the non-cooperative single-input single-output and the conventional ANF schemes. Considering channel path loss, the proposed scheme consume less total transmission energy as compared to ANF and non-cooperative scheme in more practical distance range. Thus the proposed scheme is suitable for high rate and energy efficient relay-enabled communication. In addition to that, we also present a novel power allocation scheme for multiple relay nodes that results in efficient cooperative multiple-input multiple-output (MIMO) communication. Considering channel path loss, the total transmission energy is distributed between the source and the relay nodes. The energy distribution ratio between the relay and direct link is optimized such that the quality of received signal is maintained with minimum total transmission energy consumption. We calculate the energy distribution ratio analytically and verified it through computer simulation. With the new power allocation scheme, the system also obtains an increased channel capacity as compared to cooperative scheme with conventional equal power allocation and non-cooperative scheme. Optimal relay positioning with proposed energy allocation scheme is also explored to maximize the capacity.

In planning for future electricity supplies certain issues will need to be considered such as increased energy usage, urbanisation, reduction in personnel, global warming and the conservation of natural resources. As the result, some countries have investigated the transformation of their existing power grid to the so-called Smart Grid. The Smart Grid has three main characteristics which are, to some degree, antagonistic. These characteristics are the provision of good power quality, energy cost reduction and improvement in the reliability of the grid. The need to ensure that they can be accomplished together demands much richer Information and Communications Technology (ICT) networks than the current systems available. In this research we have identified the gap in the current proposals for the ICT of the power grid. We have designed and developed an ICT architecture for the neighbourhood sub-Grid level of the electrical network, where monitoring at this level is very underdeveloped because most current grids are controlled centrally and the response of the neighbourhood area is not generally monitored or actively controlled. Our designed ICT architecture, which is based on established architectural principles, can incorporate data from heterogeneous sources. This layered architecture provides both the sensors that can directly measure the electrical activity of the network (e.g. voltage) and also the sensors that measure the environment (e.g. temperature) since these provide information that can be used to anticipate demand and improve control actions. Additionally, we have de-signed a visualisation tool as an interface for a grid operators to facilitate a better comprehension of the behaviour of the neighbourhood level of the Smart Grid. Since we have noticed that energy aware ICT is a prerequisite for an efficient Smart Grid, we have utilised two different approaches to tackle this issue. The first approach was to utilise a cluster-based communication technique for the second layer of the architecture, which comprises Wireless Sensor Networks, where energy limitation is the major problem. Accordingly, we have analysed the energy-aware topology for wireless sensor networks embedded in the mentioned layer. We provide evidence that the proposed topology will bring energy efficiency to the communication network of the Smart Grid. The second approach was to develop a data reduction algorithm to reduce the volume of data prior to data transmission. We demonstrated that our developed data reduction is suitable for Smart Grid applications which can keep the integrity and quality of data. Finally, the work presented in this thesis is based on a real project that is being implemented in the medium voltage power network of the University of Manchester where power grid instrumentation, real data and professionals in the field are available. Since the project is long-term and the environmental sensor networks in particular are not currently installed we have evaluated some of our predictions via simulation. However, where the instrumentation was available, we were able to compare our predictions and our simulations with actual experimental results.

The first focus of this thesis is a basic scientific research in the field of super-regenerative receivers (SRRs) and, in particular, super-regenerative oscillators (SROs). In chapter 3, a theoretical analysis of SROs is performed and its nonlinear behavior is studied in both time and frequency domains. The cross-coupled architecture is studied as a special case, however, widely used topology in the SRO design. The start-up and decay envelopes of the oscillator output are studied in relation to the input. The SRO start-up time and the maximal achievable quenching frequency are investigated. For phase modulation purposes, the relation between the initial phases of the input and output signals is investigated. In addition, a frequency-domain analysis is performed to ease the characterization of test circuits at high frequencies where time-domain measurements are not possible. The analytical results are verified by circuit-level simulations and measurements of a 2.4-GHz SRO. This study provides design guidelines for the design of SROs and helps in determining the optimal system parameters when targeting both amplitude and phase modulations. The SRO concept and its phase sampling capability are further studied in chapter 4. For this purpose, two SRO circuits operating around 60GHz are investigated, designed − in both CMOS and SiGe BiCMOS technologies − and characterized. Different circuit techniques are studied in order to improve the energy efficiency and maximize the switching speed. For instance, a novel quenching technique to maximize the power efficiency is presented. This circuit approach includes a pulse generator, which generates the quench signal allowing to switch the SRO with a minimum duty cycle. In fact, the SRO input is sampled at the onset of oscillation and, therefore, it is unnecessary for the oscillator to run for a long time in its steady state. This allows to minimize the on-time of the SRO and to considerably reduce its power consumption. Compared to the state of the art, the circuit achieves by far the highest power efficiency of 21.7%. In addition, a novel switching scheme is presented in order to maximize the quenching speed. This approach enables to greatly reduce the switching time constant, allowing to improve the SRO quench rate by approximately a factor of 3 compared to the state of the art. A record switching frequency of up to 10GHz is achieved. The second focus of this thesis is the investigation of on-off-keying (OOK) receivers operating at a carrier frequency of 60GHz. OOK modulation schemes have the advantage of low circuit complexity and, therefore, low power consumption and small chip area. The drawback of low spectral efficiency can be mitigated by the large bandwidth at mm-wave frequencies, in particular, at the 60-GHz ISM band, 9GHz from 57 to 66GHz, which allows to achieve high data rates. The goals of this study are enhancing the speed, maximizing the energy efficiency and improving the sensitivity. For this purpose, several circuit approaches are studied. A highly efficient envelope detector and a novel limiting amplifier architecture with simultaneously large bandwidth and high gain ensure high-speed low-power operation. A high-gain low noise amplifier is employed to increase the sensitivity. A feedforward dc-offset cancellation technique is used to ensure the proper operation of the receiver. As a proof of concept, the chips are implemented in a 130-nm SiGe BiCMOS technology. The OOK receiver achieves a record data rate of up to 20Gb/s at a bit-error-rate less than 10^(-12). The low power consumption and the ultra high speed capability allow a highly energy-efficient operation of only 2.2pJ/bit. Finally, this thesis studies the design of 60-GHz amplifiers. In fact, one of the main challenges of transmitting data at mm-wave frequencies is the high free-space path loss, which limits the transmission range. To alleviate this issue, amplifiers with high output power at the transmitter side and with low noise figure and high gain at the receiver side are required. Chapter 6 investigates the design of a low noise amplifier (LNA), with the study focus being achieving simultaneously large bandwidth, high gain, low noise figure and low power consumption in order to enable a high-speed receiver with high power efficiency and high range. The LNA achieves a bandwidth of 23GHz, a gain of 23.8dB and an average noise figure of 3.2dB and consumes only 8mW, remarkably improving the state of the art. In addition, this chapter presents the investigation and design of a 60-GHz power amplifier with an output power of up to 14.7dBm and a small chip area to ensure a sufficient communication range at the transmitter side.

Progress in energy harvesting technology and the increasing need for the energy efficient and environmentally friendly applications have called for reconsideration of communication systems. This reconsideration results in new problem formulations regarding the recent developments on energy harvesting systems. Recently, optimal strategies for various types of energy harvesting networks have been developed based on different harvesting models. This thesis reports the results of our research to develop the optimal scheduling structures on an energy harvesting broadcast and fading channels, and to devise online implementable algorithms for a point-to-point communication system. Particularly, structural properties of an optimal offline schedule in, (1) an energy harvesting broadcast channel with one transmitter two receivers, (2) a single user communication system under fading conditions, are investigated. Moreover, an online algorithm is proposed for a single-user energy harvesting communication system considering the physical constraints and necessities regarding implementation. The proposed scheme is implemented through GNU Radio framework on a USRP device.

The thesis deals with the instrumentality of usage efficient communication and prosocial activities on primary children´s behaviour in class after-school club. The observed areas are coping, solving plus percent occurrence of conflicts, mutual communication together with the expression of personal opinions. Furthermore, the work compared the atmosphere within the class after-school club before the research in January 2014 and after its completion in June 2014. The results of the empirical investigation of quantitative research are compared with each other at the beginning as well as at the end of the research. These outcomes were compared with the results of the control group. They prove that the change of educational approach by using the effective communication and prosocial activities can affect children's behavior.

Group communication, security and 5G technology present a unique dimension of challenges and security remains crucial in the successful deployment of 5G technology across different industry. Group key management plays a vital role in secure group communication. This research work studies various group key management schemes for mobile wireless technology and then a new scheme is proposed and evaluated. The main architecture is analysed, while the components and their roles are established, trust and keying relationships are evaluated, as well as detailed functional requirements. A detailed description of the main protocols required within the scheme is also described. A numerical and simulation analysis is employed to assess the proposed scheme with regards to fulfilling the security requirement and performance requirements. The impact of group size variation, the impact of mobility rate variation are studied with regards to the average rekeying messages induced by each event and 1-affects-n phenomenon. The results obtained from the simulation experiments show that the proposed scheme outperformed other solutions with a minimal number of rekeying messages sent and less number of affected members on each event. The security requirements demonstrate that backward and forward secrecy is preserved and maintained during mobility between areas. Finally, the research work also proposes a 5G-enabled software-defined multicast network (5G-SDMNs), where software-defined networking (SDN) is exploited to dynamically manage multicast groups in 5G and mobile multicast environment. Also, mobile edge computing (MEC) is exploited to strengthen network control of 5G-SDMN. / National Open University of Nigeria

Lågströmskommunikationsprotokoll såsom 6LoWPAN har använts i stor utsträckning för applikationer som kräver mindre energiförbrukning för trådlös kommunikation på korta avstånd, exempelvis IoT-enheter. Eftersom antalet sådana enheter ökar blir det allt viktigare att överväga ambient energy harvesting som en energikälla för att driva sådana enheter. Det framkallar ett behov av att ompröva designen av ett energieffektivt kommunikationsprotokoll som gör det möjligt för sensorer och aktuatorer att använda den utvunna energin för beräkning och kommunikation. Eftersom den utvunna energin från en energikälla är begränsad och det tar tid för en enhet att samla tillräckligt med energi för datahantering och kommunikation, finns det ett behov av att undersöka energibudgeten och bestämma de kritiska parametrarna som påverkar energiförbrukningen för trådlös kommunikation. En analys av energiförbrukningen utfördes genom att anpassa en Python-modell och simuleringar genomfördes för att hjälpa till att förstå påverkan av nyckelparametrar på energiförbrukningen med hänsyn till en lämplig radio frequency energy harvesting (RF-EH) för “zero” energienheter. I examensarbetet föreslås designöverväganden för ett nytt lågströmskommunikationsprotokoll för “zero” energienheter. Resultaten visade att adaptive data rate (ADR) har en stor betydelse för energibesparingar. Med lämpliga överföringsparametrar inställda kan energiförlusterna för omsändningar och kollisioner minskas. Det är också möjligt att införa en schemaläggningsalgoritm för kommunikationsprocessen för förbättrad kollisionsundvikande. De föreslagna designövervägandena kan tillämpas i framtida arbeten för att förbättra kortdistanskommunikationsprotokollet för “zero” energienheter. / Low power communication protocols such as 6LoWPAN have been widely used on applications that require less energy consumption for short-range wireless communication, for example, Internet of Thing (IoT) devices. As the amount of these devices escalates, it becomes increasingly important to consider ambient energy harvesting (EH) as an energy source to power such devices. This induces a need to reconsider the design of an energy-efficient data transfer protocol that enables the sensors and actuators to utilize the harvested energy for computing and communication. As the harvested energy from an energy source is limited and it takes time for a device to accumulate enough energy for data processing and communication, there is a need to investigate the energy budget and determine the critical parameters that affect the energy consumption for wireless communication. An energy consumption analysis was performed by adapting a Python model, and simulations were carried out to help understand the impact of key parameters on energy consumption while considering a suitable range for radio frequency (RF) energy harvesting “zero” energy devices. The thesis project aims to propose the design considerations of a new low-power communication protocol for “zero” energy devices. The results showed that adaptive data rate (ADR) has a major contribution to energy saving. With suitable transmitting parameters set, the energy waste of retransmissions and collisions could be reduced. It is also possible to introduce a scheduling algorithm to the communication process for improved collision avoidance. The proposed design considerations can be applied in future work to improve the shortrange communication protocol for zero-energy devices.