Reduction of interference using unidimensional interference alignment scheme with rls-mmse equalization technique in STFBC MIMO-OFDMA system / Nor Azlizan Hussien

In broadband wireless data services, the demand for the high data rates, improved coverage and quality of radio link have increased extremely. These system requirements can be met with the combination of two powerful technologies in the physical layer design; Multiple Input Multiple Output (MIMO) and orthogonal frequency division multiple access (OFDMA). These marvel combination assures to provide the system with high data rates over frequency selective fading channels, and one of the leading candidates for the next generation of wireless communication systems. However, OFDMA inherits the infirmity of orthogonal frequency division multiplexing (OFDM) which is vulnerable to Carrier Frequency Offsets (CFO) and hence, generates Inter-carrier Interference (ICI) among achieved in the system when exploiting space, time, and frequency domains. Therefore, diversity order is applied to improve the system performance and at the same time, makes the system more robust to the ICI caused by CFO. In addition to that, the Inter-symbol Interference (ISI) is also being considered due to the fact that different mobile users will propagate through different channels and produce time dispersion of multipath channel. Based on these issues, the objective of this research is to mitigate the said interferences and achieves higher diversity order throughout the system. Essentially, ICI problem can be overcome through Unidimensional Interference Alignment (IA) scheme and RLS-MMSE equalization technique is proposed to mitigate the ISI problem, and at the same time space time frequency block codes (STFBC) of diversity order technique is used to achieve full diversity order in the system. Overall, by using STFBC Unidimensional IA scheme with RLS MMSE equalization technique, the BER and PEP performance of the system is improved by 16.1 % and 36.8 % respectively