Research And Development Of MIMO-OFDM Real-time Platform With Multiple Antennas

The next-generation wireless communication systems can provide higher data transfer rate in wireless mobile environment inorder to meet people’s increasing demands for multimedia services (image, audio and data combined together). As we know, traditional wireless communication systems can reach a high rate of data transfer only by occupy wider bandwidth or use higher level modulation, so the limitation of available wireless bandwidth and higher level modulation technique influences the performance of the traditional wireless communication systems greatly.The MIMO (Multi-Input Multi-Output) technique can improve channel capacity through the spatial multiplexing gain and get lower bit error rate through the spatial diversity gain. OFDM (Orthogonal Division Frequency Multiplexing) technique can overcome the ISI (intersymbol interference) caused by multipath propagation with low complex processing and allocates resources flexibly. With its unique characteristics in improving data transfer rate, reducing the multipath fading and so on, MIMO-OFDM is widely considered to be one of the most important technologies for the next-generation wireless communication systems. Recently, IEEE802.11has become the mainstream standard in WLAN. The standard of IEEE802.11n supports MIMO-OFDM technology which will increase WLAN transmission rate to108Mbit/s above (up to320Mbit/s).The traditional MIMO-OFDM systems based on theory and software can no longer satisfy the current needs in research and application, the requirements of establishing a MIMO-OFDM hardware real-time communication platform is imminent. Based on the development of multiple input and multiple output testbed, this paper aims to build a MIMO-OFDM transceiver system which combines software with hardware. It has many features like opening, easy to evaluation, portablely systematically and so on, which can meet the needs in education, researching and industry. In addition, this paper also introduces an adaptive transmission technique which can be used in MIMO-OFDM systems, with this technique, the platform can adjust parameters during operation to minimize various kinds of interference in wireless environment.This real-time platform is divided into two parts, the transmitter and receiver. Both parts are composed by antennas, RF transceiver, and custom PC. The real-time signal processing is achieved with the help of Sundance’s digital signal processing platform which contains DSP、FPGA、D/A and A/D tasks. Unique from others, this system uses the method of modular design, making the platform design and operation more simple, flexible and straightforward, the developer can programming with Matlab and then transplanted to the hardware. In this system, data can be transferred through real wireless transmission channels which can overcome the limitations of channel simulation models. It can be utilized in implementing and assessing the latest MIMO-OFDM algorithms. The real time operation of the whole system satisfies a systemic validation which can fulfill the rapid transform from the experimental testbed to the final product.