Indoor Characterisation using High-Resolution Signal Processing Based on Five-Port Techniques for Signal Input Multiple Output Systems

Problem statement: The development of wideband mobile communication systems requires a deep knowledge of the characteristics of the indoor mobile radio channel. The characterization of the indoor multi-path propagation structure is important in developing antifading techniques for high-speed digital radio access. The high-resolution of the estimation of the Time of Arrival (ToA) and the Direction of Arrival (DoA) of multi-path signals in wireless communication involves locating a source of Radio Frequency (RF) waves and then directing the beam of antenna in the estimated direction. The time dispersion is relatively small and the frequency dispersion is rather low compared to those expected in outdoor environments. Those characteristics require a high resolution system. This improved the performance of communication system. Approach: The DoA was estimated by measuring the phase difference of signals detected by an antenna array while the estimation of ToA was based on the phase difference measured over two successive frequencies. Low cost and high-resolution were obtained by using five-port receivers and the MUSIC algorithm. The simulation of five ports junction was developed using Advanced Design System (ADS). It was used to optimize the parameters of the structure and the antennas. Results: We obtained the adapted ring with the desired functions, splitting the received power equally over the output branches with a dephasing of 120°. The corresponding output signals appear with an amplitude variation depending on the dephasing between the RF and OL signals. Conclusion: Simulation results, performed around the 2.4 GHz frequency, showed an excellent estimation of the ToA and DoA with a high resolution and a reduced errors in both the time and the direction of multi-path signals.