Towards reliable and high data-rate wireless communication systems

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In recent years, residential, business and mobile users are combining high speed internet access with real-time applications such as voice and video which results in high data rate wireless communication systems. In these systems, achieving high reliability is a very challenging task due to multi-path fading. The recent technology called "Multiple-Input Multiple-Output" (MIMO) promises a solution for this problem.A common drawback of MIMO transmission schemes is that they are not flexible in rate-performance tradeoff. Some work has been reported to address this problem but more novel approaches are required for addressing increasing data-rate requirement of mobile users. Another drawback of MIMO systems is complexity of the mobile receiver due to availability of multiple antennas. To resolve this problem, technologies will be developed to achieve small and low cost mobile units.For more efficient use bandwidth in today's multi-rate wireless systems, signaling parameters must adapt to varying channel conditions and required quality of service. Therefore, adaptive coding and modulation which is a standard feature of modern wireless systems including MIMO-OFDM has to be developed. This is another topic to be investigated in the proposed research.Design of a new Space, Time and Frequency spreading technique for MIMO OFDM-CDMA is another important task to be performed in this project. In addition to improved performance via diversity, space-time-frequency spreading offers increased degrees of freedom in multiple access scheduling. Motivated by the fractional frequency reuse in WIMAX standard, multiple access scheduling schemes will be developed to fully taking advantage of the increased degrees of freedom in MIMO OFDM-CDMA.