| With the development of mobile communication system to a wider bandwidth and more rapid transmission speed, more and more new technologies emerge at the right time. To assess the new technologies and improve system performances, the measurement and modeling of wireless channels, as the fundamental work, become full of significance. Meanwhile, the requirement of communication services which happens indoor increase dramatically, making indoor environment become the most widely used scenario. However, indoor scenarios have different structures, which mean different indoor scenarios show different channel propagation characteristics. Besides, propagation property depends on carrier frequency.2.35GHz is one of the application carrier frequencies of LTE (Long Term Evolution) in China; while3.5GHz is pushed in indoor enhance application in LTE-Advanced system. As a result, conducting measurement and building channel models in indoor multi-scenarios under2.35GHz and3.5GHz is full of importance.Focusing on indoor office environment, we divide it into open office scenario and traditional indoor office scenario. We conduct abundant field measurements in these scenarios under2.35GHz and3.5GHz, and analyze large-scale shading characteristics, like path loss and shadow fading and small-scale shading characteristics in delay and spatial domain. The main and important conclusions are drawn as follows:(1) For indoor open office environment, we conduct measurements in multi-floors scenarios under2.35GHz. When signals penetrate one floor, attenuation reaches to13dB. The attenuation value is related to the material and thickness of floor and propagation losses do not increase linearly in dB with an increasing number of floors or walls. Besides, based on the statistical results from channel measurement, we have investigated the delay characteristics on the same floor and on multi-floor in open office scenario. When Rx and Tx are on the same floor, RMS (Root-Mean-Square) delay spread for the LOS (Line-Of-Sight) and NLOS (None-Line-Of-Sight) conditions are36ns and53ns, respectively. With more floors crossed, delay parameters increase to some extent when the received multipath components have enough power. And RMS delay spread for three floors are well fitted by LogNormal distributions. Besides, there is nearly no evident difference about delay parameters crossing one floor upwards or downwards and multipath effect is alike caused by crossing floor or wall. Furthermore, linear relations between RMS delay spread and mean excess delay are applied and well fitted to our statistical data. It is suggested that RMS delay spread changes with mean excess delay faster unde a more complicated propagation condition.(2) For traditional indoor office scenario, we use dipole and ODA (Omni-Directional Array) antennas to conduct measurement under3.5GHz in corridor-corridor, corridor-room, room-room and room-corridor scenarios. In LOS condition, path loss is3-5dB smaller than standard models, so we can revise standard models subtly according to simulation conditions. In addition, path loss is larger in NLOS condition so that we can’t ignore the attenuation of concrete walls. As for delay parameters, they are consistent with the results of indoor office scenario in WINNER Ⅱ model. In corridor-corridor scenario, a strong reflection multipath component exists, leading to the maximum RMS delay spread and max excess delay. The statistical spatial parameters of both angle-of-arrival and angle-of-departure are much larger than that in standard models, and cross polarization discrimination is smaller, which indicates this environment is full of scatters.So we can use the precious measurement data and valuable conclusions in indoor open office and traditional office scenarios under2.35GHz and3.5GHz, for design, simulation and evaluation of LTE and LTE-Advanced mobile communication systems to reflect the realistic propagation environment better. |
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