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

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