Abstract
Recently, more and more next-generation wireless communication systems adopt orthog-onal frequency division multiplexing (OFDM) as their transmission scheme due to its good spectrum efficiency. Furthermore, orthogonal frequency division multiple access (OFDMA) combines OFDM and frequency division multiple access (FDMA) and making OFDM systems more and more flexibility and efficient in managing the channel bandwidth. Besides, multi-input multi-output (MIMO) techniques enhance the system performance or data rate greatly under limited channel bandwidth. As a result, by combing MIMO and OFDMA, new high-speed wireless communications enjoy the benefits from both technologies. In this thesis, the system design and hardware implementation of a 4x4 MIMO-OFDMA downlink transceiver is proposed. The proposed transceiver consists of a symbol timing synchronization block, a carrier frequency offset (CFO) estimator and compensator, a phase compensator, a channel estimator, a MIMO detector, and a space-frequency block codes (SFBC) decoder. In the symbol timing synchronization block, the low complexity architecture of the delay-and-correlator and the matched filters with quantized coefficients are proposed. Furthermore, in or- der to save hardware cost, we implement the hardware-shared boundary detector/integer CFO estimator. The proposed fractional CFO estimator and compensator substitute the COordinate Rotation DIgital Computer (CORDIC) arctangent and CORDIC sin-cosine architecture for the loop-up table implemented by read-only memory (ROM). The CORDIC not only decreases ROM utilization greatly but also has high degree of accuracy for the CFO and sampling frequency offset (SFO) estimation. Linear interpolation and coefficient approximation technique are applied in channel estimation for reducing hardware complexity but still with high perfor- mance. The proposed 4x4 MIMO-OFDMA downlink transceiver supports spatial multiplexing for the MIMO detector and SFBC technique for the SFBC decoder. In the static or low mobility environment, adopting the spatial multiplexing in the MIMO system could acquire more capacity gain and increase more data throughput compared with the single-input single-output (SISO) system. In high mobility environment, theMIMO system using the SFBC mode could provide more diversity gain than the SISO system to against the inter-carrier interference (ICI) effect induced by Doppler Effect. The proposed 4x4 MIMO-OFDMA downlink transceiver in SFBC mode can operate in 300km/hr high mobility environment according to the simulation result. Finally, the proposed receiver architecture is emulated in Altera Stratix II EP2S180 board and integrated into Advanced RISC Machine (ARM) system on chip (SoC) platform.