A statistical model for the dual polarised MIMO land mobile satellite channel at S-band

This thesis explores channel modelling approaches to the land mobile satellite (LMS) channel in S-band, focussing on the implementation of multiple input multiple output techniques through the use of dual polarisation. An Enhanced Statistical Model is presented and the output of this model is analysed and compared to the two current state-of-the-art models that simulate the dual polarised LMS channel, i.e. the statistical Liolis-CTTC model and the geometric ray-tracing QuaDRiGa model. The enhanced model builds on the Liolis-CTTC model and presents solutions to a number of issues that arise in the statistical modelling process. The enhancements in the new model include imposing temporal correlation on the slow variations without unwanted high frequency components from low-pass filtering, introducing Doppler effects including Doppler shaping of the fast variations, implementing a smooth state transition process and also implementing an interpolation process to sample the channel at the required sub-symbol rate for transmission. In addition to the analysis of the three models, real channel measurements of the dual polarised LMS channel from the MIMOSA campaign are analysed. A statistical comparison between the models and the real measurement data for simulated journeys in a number of user environments is conducted through analysis of the timeseries, the cumulative density function (CDF), average fading duration (AFD) and level-crossing rate (LCR). Capacity analysis and eigenvalue analysis is also conducted and allows for validation of the enhanced model. The comparisons with the measurement data show good agreement between the real measurement data and the enhanced model

MIMO application for the quadrifilar helix antenna

Capacity increase of the current land mobile satellite (LMS) communication systems is highly desirable to cater for more data-centric applications such as broadcasting. Since the Multiple-input Multiple-output (MIMO) offers high spectral efficiency without additional bandwidth and transmit power, its implementation in the LMS system has been widely investigated in terms of channel characterisation, channel modelling and coding algorithms. However, the aspect of receive antenna design and its performance evaluation has not yet been considered even though it has enormous impacts on the system performance. This thesis presents a study on designing a novel dual circularly polarised receive antenna system for the LMS MIMO system that utilises the printed quadrifilar helix antenna (PQHA) and also the required performance evaluation methods. The PQHA was miniaturised using two new methods, which are the element folding and combination of element folding and meandering where more than 50% size reduction can be achieved. These miniaturised PQHAs were combined to create a variety of dual circularly polarised arrays such as the dual circularly polarised single folded PQHA (SFPQHA) horizontal array and folded meandered PQHA (FMPQHA) vertical array. For evaluating the branch power ratio of these arrays, a newly derived formulation of the mean effective gain (MEG) in a Ricean fading channel that incorporates the polarisation of the line-of-sight (LoS) component and the corresponding antenna gain has been proposed. Further evaluation of these arrays as the receive antenna in this system was carried out using measurement campaigns. Results show that both arrays provide substantial capacity increase when compared to a single link system in both LoS and NLoS channels. A more comprehensive study on the effect of antenna properties was conducted using a newly, developed channel model that integrates the array characteristics with the propagation channel. This modelling approach allows for a performance comparison between the designed SFPQHA array and other antennas to be easily implemented, which is very useful in the process of designing MIMO antennas.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Modelling and and measurement analysis of the satellite MIMO radio channel

The increasing demand for terrestrial and satellite delivered digital multimedia services has precipitated the problem of spectrum scarcity in recent years. This has resulted in deployment of spectral efficient technologies such as MIMO for terrestrial systems. However, MIMO cannot be easily deployed for the satellite channel using conventional spatial multiplexing as the channel conditions here are very different from the terrestrial case, and it is often dominated by line of sight fading. Orthogonal circular polarization, which has long been used for increasing both frequency reuse and the power spectral density available to earth-bound satellite terminals, has recently been recommended for directly increasing the throughput available to such devices. Following that theme, this thesis proposes a novel dual circular polarisation multiplexing (DCPM) technique, which is aimed at the burgeoning area of throughput-hungry digital video broadcasting via satellite to handheld devices (DVB-SH) and digital video broadcast to the next generation of hand held (DVB-NGH) systems. In determining the working limits of DCPM, a series of measurement campaigns have been performed, from which extensive dual circular polarised land mobile satellite (LMS) channel data has been derived. Using the newly available channel data and with the aid of statistical channel modelling tools found in literature, a new dual circular polarised LMS MIMO channel model has been developed. This model, in contrast with previously available LMS MIMO channel models, is simpler to implement since it uses a distinct state-based empirical-stochastic approach. The model has been found to be robust and it easily lends itself to rapid implementation for system level MIMO and DCPM analysis. Finally, by way of bit error rate (BER) analysis in different channel fading conditions, it has been determined when best to implement polarisation multiplexing or conventional . MIMO techniques for DVB-type land mobile receivers. It is recommended that DCPM be used when the channel in predominantly Ricean, with eo-polar channel Rice factors and sub-channel cross correlation values greater than 1dB and 0.40 respectively. The recommendations provided by this research are valuable contributions, which may help shape the evolving DVB-NGH standardisation process.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Uncoded space-time labelling diversity : data rate & reliability enhancements and application to real-world satellite broadcasting.

Doctoral Degree. University of KwaZulu-Natal, Durban.Abstract available in PDF

The characterisation and modelling of the wireless propagation channel in small cells scenarios

“A thesis submitted to the University of Bedfordshire, in partial fulfilment of the requirements for the degree of Doctor of Philosophy”.The rapid growth in wireless data traffic in recent years has placed a great strain on the wireless spectrum and the capacity of current wireless networks. In addition, the makeup of the typical wireless propagation environment is rapidly changing as a greater percentage of data traffic moves indoors, where the coverage of radio signals is poor. This dual fronted assault on coverage and capacity has meant that the tradition cellular model is no longer sustainable, as the gains from constructing new macrocells falls short of the increasing cost. The key emerging concept that can solve the aforementioned challenges is smaller base stations such as micro-, pico- and femto-cells collectively known as small cells. However with this solution come new challenges: while small cells are efficient at improving the indoor coverage and capacity; they compound the lack of spectrum even more and cause high levels of interference. Current channel models are not suited to characterise this interference as the small cells propagation environment is vast different. The result is that overall efficiency of the networks suffers. This thesis presents an investigation into the characteristics of the wireless propagation channel in small cell environments, including measurement, analysis, modelling, validation and extraction of channel data. Two comprehensive data collection campaigns were carried out, one of them employed a RUSK channel sounder and featured dual-polarised MIMO antennas. From the first dataset an empirical path loss model, adapted to typical indoor and outdoor scenarios found in small cell environments, was constructed using regression analysis and was validated using the second dataset. The model shows good accuracy for small cell environments and can be implemented in system level simulations quickly without much requirements

Tri-Orthogonal Polarisation Diverse Communications

This thesis investigates improving communication link coverage through triorthogonal polarisation diversity. Tri-orthogonal polarisation diversity exploits radiated electromagnetic energy transmission and reception in three orthogonal spatial directions with an aim to provide enhanced communication link performance. Original contributions to this branch of diversity are presented in areas of both software and hardware design. First, simulations are presented highlighting the benefit of tri-orthogonal polarisation diversity at both the transmitter and receiver over a range of terrestrial channel conditions. The results are presented in an easily understandable graphical format that results from a novel model design considering all antenna orientations. Orientation robustness at the antenna is demonstrated as a consequence of a tri-orthgonal polarisation diverse approach. Second, additional research is performed in order to extend the model into the field of satellite systems. The ionosphere is required to be modelled, and this is performed according to a novel vectorised approach using realtime ionospheric data and terrestrial magnetic field appreciation. Third, ionospheric modelling is incorporated into a non-geosynchronous satellite orbit channel model that provides an insight into the benefit of applying a tri-orthogonal polarisation diverse approach uniquely at the receiver. Novelty is provided in the form of a vectorised approach to simulation covering all antenna orientations in a field-ofview as observed from a satellite transmitter. This is extended over the orbits of three distinct satellite systems. Output is provided in graphical format and conclusions are drawn form the data which suggest that a tri-orthogonal polarisation diverse approach applied at the receiver provides an increase in reception performance. Fourth, an antenna is designed, simulated, constructed and tested that provides three orthogonal polarisations in a phase-centred differentially-fed package. Novelty is provided in the design being planar in nature, with three orthogonal modes being able to be transmitted from a single slot. Results emanating from the testing procedure demonstrate the benefits of the design in terms of diversity and extension to beamforming applications. Fifth, as an extension to the antenna design, a circularly polarised feeding arrangement is used together with an omnidirectional vertically polarised mode feed in an antenna and feed combination. This provides the possibility of a direct comparison with conventional circularly polarised techniques, such as those used in both terrestrial and satellite receive antennas. Sixth, the operational bandwidth of the omnidirectional vertically polarised mode is extended by adapting the design of the cavity wall resonating slots in a substrateintegrated monopole antenna while maintaining a planar structure. The electric monopole design demonstrates an increase in operating bandwidth from 2.5% to 56%. In the thesis, a tri-orthogonal polarisation diverse approach is shown to be beneficial to signal reception over a range of channels, both in the areas of terrestrial and satellite communications. The concept is demonstrated to be feasible in a planar structure. Triorthogonal polarisation diversity is likely to play an increasing role in the future as systems look to cope with an ever increasing data flow. The demand for content on mobile devices has forced massive growth in mobile data over the past two decades. This growth has recently reached saturation point, and so new avenues for extending growth have to be considered. A search for available bandwidth has lead research to focus on the mmWave section of the electromagnetic spectrum. The advent of the next generation of wireless connectivity, dubbed fifth generation or 5G, is now upon us (Rappaport et al. 2013b). With data traffic set to multiply by up to one thousand fold by 2020 (Qualcomm Inc. Accessed: 2014b, Qualcomm Inc. Accessed: 2014a, Li et al. 2014, Chin et al. 2014), as The Internet of Things (Ashton 2009, Cisco Inc. Accessed: 2014, Gubbi et al. 2013) enters into the fray, an overhaul of wireless design is somewhat overdue. For static point-to-point, or LoS systems, challenges exist according to the channel environment and temporal changes that may occur within. For any network that has a mobile component built in, where spatial position and alignment of transmitter and receiver change over time, signal propagation is additionally influenced by link geometry. In an increasingly mobile world, this presents challenges as increased coverage, one of the main focus points of the 5G system, will require efficient use of radiated electromagnetic energy. Conventional techniques for improving data rate have typically aimed at increasing performance at the transmitter. For terrestrial networks, a transmitter is typically stationary. Performance outweighs size constraints and so power amplification and combination may be used to excite antennas that flood a network cell with a strong linearly polarised transmitted signal. For commercial providers, this has proved a very successful technique, mainly as a result of the majority of wireless subscribers living in dense urban environments. For a linearly polarised wave, operating at conventional operating frequencies around 2 GHz, and transmitted with relatively high power, the urban environment typically provides assistance for signal reception at the receiver through diversity brought about by reflection, refraction and scattering or multipath due to the presence of buildings. Small misalignments in transmit and receive antennas are mitigated as the propagating signal wavelength is large and a relatively high transmit power establishes a relatively high signal-to-noise ratio, providing useful multipath effects over the channel. At certain receive positions, channel fading may occur when superposition of received multipath components effectively cancel each other. This may be mitigated through additional transmitters that are spaced appropriately; a concept known as spatial diversity that has been cited at mmWave frequencies (Smulders 2002, Park and Pan 2012). Diversity of signal is important in that it offers a greater possibility of a signal being received due to individuality of uncorrelated channel propagation for each diverse signal component. As more content is demanded by subscribers within an ever shrinking timeframe, a higher frequency of operation is typically required for a carrier wave capable of providing this service. Add in the context of mobility, and issues quickly appear. Beneficial effects on a linearly polarised signal operating at conventional low gigahertz frequencies arising from reflection, refraction, and scattering or multipath effects, assist signal reception. Relatively long wavelengths are subjected to many scatterers, and due to the relatively high transmit power involved, scattering effects provide diversity at the receiver in the form of many smaller receivable diverse signal components. These signal components are superpositioned either constructively or destructively, after diverse individual propagation through the channel, at the receiver to provide signal reception. At mmWave frequencies, due to a shrinking wavelength, the following issues arise: • increased path loss over a defined range due to spreading loss (Pozar 2011), and increased atmospheric absorption (Liebe et al. 1989). An obvious solution is to provide more transmit power at the transmitter. At higher frequencies, miniaturisation of devices limits this possibility as heat sinking becomes problematic. Amplifier non-linearity and unwanted third order intermodulation impact on system performance (Niknejad and Hashemi 2008, Hashemi and Raman 2016) • the beneficial effect of multipath fading may not exist in a mmWave terrestrial channel (Pi and Khan 2011), as a smaller wavelength typically implies a reduced beamwidth and less scatterers available for the LoS signal to scatter into useful smaller diverse signal components. Due to a relatively low transmit power involved, any scattering of a LoS signal into smaller, weaker diverse signal components may result in no received signal. As a result, cell range is reduced and more transmitters are required to provide coverage over a network • with a shrinking wavelength, relatively lower transmit power, and increased mobility, antenna misalignment becomes problematic. A drive for radiated power efficiency is paramount in providing the next generation of wireless networks. An ability to transmit signals into and receive signals from all angles is necessary (Rappaport et al. 2013b). The terahertz range, for example, offers extremely high transfer rates, although any small misalignment greatly affects rate. The use of dielectric mirrors is required to effectively steer the transmitted signal to its destination. Mitigation of misalignment becomes important in maintaining system performance. For the next generation of mobile wireless systems to operate within the mmWave section of the electromagnetic spectrum, a solution to extend range is to increase radiated energy in a direction of propagation, through beam steering techniques. Within a mobile context, this poses challenges, not least as the link geometry is variable. For terrestrial networks, conventional transmitted waveforms are mainly vertically polarised, or circularly polarised, and as such are mainly one dimensional, or two dimensional at best, in performance. To provide the next generation of wireless networks, a third dimension needs to be considered to provide efficient use of radiated electromagnetic energy. Frequency bands of interest for 5G systems differ from country to country. According to the US Federal Communications Commission (FCC), the mmWave region that will be studied ranges from 24–80 GHz (Rappaport et al. 2013b, Rappaport Accessed: 2014, Above Ground Level Media Group Accessed: 2015). One of the aims of 5G is to improve coverage (Rappaport et al. 2013b). One method that is being considered is the joining of terrestrial and satellite services into one seamless network that may be readily accessed by the subscriber at the receiver (Evans et al. 2005, Evans et al. 2015, Federal Communications Commission Accessed: 2016). Satellite networks provide their own specific challenges, as transmit power is limited to payload specifications, and coverage typically requires a satellite that is moving relative to the Earth’s surface. Once again we find ourselves facing the same three issues that we encountered within the terrestrial context of a mmWave channel. If we are to increase link performance in a satellite channel to complement any improvement in terrestrial channels then the following points need to be considered: • propagation using higher operating frequencies typically suffers from higher path losses (Liebe et al. 1989, Pozar 2011). In some circumstances this can be mitigated by higher transmit power, but not all. A satellite payload is subject to a strict payload capacity and this restricts the size of transmit power devices and hence available transmit power that can be launched into orbit • a lack of beneficial reflectors, refractors, and scatterers is observed during channel propagation as the signal is typically LoS, narrow in beamwidth, and weak due to higher path loss and lower transmit power (Pi and Khan 2011). Multipath effects may degrade system performance as signals are weak • an evolving link geometry that affects antenna alignment. Linear and circular polarised signals are only two dimensional in nature. Three dimensions need to be considered, and beam steering of radiated power to provide the required range is a requirement (Evans et al. 2005, Hong et al. 2014b). To ensure that the next generation of mobile systems are fully mobile, while providing increased data rate, we need to consider diversity in three dimensions. Beam steering of a transmitted signal with high gain in the direction of a receiver is one viable option, and in the context of full mobility, three dimensional signal transmission and reception appears a logical step to achieving this (Hong et al. 2014a). While at a terrestrial transmitter, it is suggested that size is not a constraint, it remains so for a satellite transmitter, as it is at a mobile receiver. This rules out spatial diversity as an approach to increasing system performance. One approach of increasing diversity within a confined volume is through polarisation techniques (Vaughan 1990). In this thesis, we investigate the benefit of a subset of this approach—tri-orthogonal polarisation diversity (Andrews et al. 2001). In effect, the concept provides at least one additional degree of freedom or layer of diversity over conventional techniques such as circular polarisation. Due to orthogonality in three directions, this approach has a wide field of view, and potentially offers diversity and improved system performance through beam steering in any unit direction. Tri-orthogonal polarisation diversity may be applied either at the transmitter, at the receiver, or at both. In Chapter 1 of the thesis, both novel software and hardware aspects of the research are highlighted. Overall, the research outcomes of this thesis from both simulation and measured results suggest that the concept of tri-orthogonal polarisation diversity is: • beneficial to wireless performance over a majority of antenna orientations • plausible for implementation within typical antenna volume constraints.Thesis (Ph.D.) -- University of Adelaide, School of School of Electrical and Electronic Engineering, 201

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

Cooperative Radio Communications for Green Smart Environments

The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin