Space- Time Block Coding (STBC) are used to improve the transmission reliably and spectral efficiency of MIMO systems. The cooperative communication techniques can avoid the difficulties of implementing actual antennas array by converting the single-input single-output (SISO) system into a virtual multiple-input multiple-output (MIMO) system. When STBC applied to cooperative diversity the system termed as Distributed Space Time Block Code (D-STBC). Most of the existing research assumes perfect synchronization among cooperative users in D-STBC. Unfortunately, perfect synchronization is almost impossible to be achieved. Therefore, most of the designed space-time codes are no longer valid. There are different research efforts to overcome this problem; most of which has high decoding complexity. In this research, two low decoding complexity schemes for imperfect synchronized D-STBC have been proposed. The first scheme is based on the principle of parallel interference cancellation (PIC), whereas the other is based on successive interference cancellation (SIC). These approaches have been proved to be a very effective in suppressing the impact of imperfect synchronization.

The increasing demand on microwave spectrum for communication systems has been the driving force in the filter industry. There are increasing demands on high performance single- and multiple-band filters. In this work, different resonator structures have been investigated for narrow band filters. Using these structures, two single symmetric and asymmetric narrow passband HTS filters has been developed. A cost-function for an optimisation algorithm to achieve multiple passband filtering function has been discussed. Different HTS Filters have been designed and tested. A new analytical algorithm to realise multiple-band filters has been developed. By cascading a passband filter with one or more stopband filters, the transfer function of the system can be manipulated to allow for implementing it as a single cross-coupled resonator filter.