Study On The Directional Multi-beam Smart Antenna Test Bed

In the past decades, the adaptive smart antennas, have been found attractive to telecommunication engineers for dramatic system performance improvements when applied in cellular mobile communication systems. Generally speaking, significant improvement of carrier to interference ratio of the system can be achieved in this way. As a result, the capacity and channel transmission quality can be improved.However, due to the complexity of the real radio propagation environment and the limit of the DSP capability, the smart antennas in mobile systems have not be able to process real-time signal. In fact, the antennas' features should be considered much more, the hardware features of the antennas should be used to complete space filtering. The directional multi-beam smart antenna in this research technique uses many directional antennas to form array. The directional beams divide space, and the directional antenna array can complete space filtering. Because of this reason, the directional multi-beam smart antenna has the advantage of real-time signal processing and high-gain.The paper designs a IF test bed of directional multi-beam smart antenna for researching the theory further and the realization problem. The paper researches some linchpin technology of three parts of test bed and made relevant design.First of all, the paper researches the important part: RF front-end which is always neglected. The digital AGC is designed by discussing the circuit structure of RF front-end and combining the back circuit of the test bed to achieve a large dynamic range and broadband RF front-end.Secondly, the paper design the principal part of test bed by SDR which is named digital IF receiving platform. This part mainly digitalize IF signal, down convert frequencies and process the final digital signal. The AD converter AD6645 is used to sampling and the digital down-converter HSP50124B is used to down convert the sampling signal. The processed signal is sent into digital signal processor TMS320C6701 to complete switch-beam. Because of the TMS320C6701 have had some mature application temples, we don't discuss the DSP here.Finally, we introduce a kind of switch beam algorithm based on CIR and emulate the performance of this switch beam algorithm.