| Recently, increasingly importance has been attached to the study ofthe low-altitude air-ground communications since the gradual opening ofChina’s low level areas. It is necessary to establish a suitable channelmodel for the environment in order to improve the whole systemperformance.The Low-altitude airspace is defined as the region within3km fromthe ground. Since the flight of an aircraft has different conditions,featuring En-Route, Arrival and Takeoff, Parking and Flying overscenarios, the channel then has different characteristics in fading, dopplershift and time delay. It is necessary to propose different models.The technical characteristics and network architecture of TD-LTEsystem have been firstly proposed. Then we discuss the mechanism andfading characteristics of large–scale fading and small-scale fading.Based on the analysis above, wireless communications system channelmodeling is proposed. For large-scale fading, we simulate a couple ofcommon large-scale fading models, analyze the range and fading wave ofeach model and present the optimization plan based on measured data. For small-scale fading, an improved Jakes model is proposed for betterperformance in correlation properties.We introduce random variables inour model, and do not affect the envelope characteristics of Rayleighdistribution. The proposed model is presented for simulating Ricianfading channel, which can perform well too.This paper also discusses the modeling and simulation of the lowaltitude aeronautical channel. According to real conditions in low levelair-ground channel, characteristics of different scenarios are analyzed andlarge-scale fading channel, small-scale fading channel are appliedrespectively. Finally, we simulate the BER performance of TD-LTEsystem. The results show that LTE can support low altitude aeronauticalchannel well. And the BER performance of each scenario is of difference.It is reasonable to classify the channel by scenarios. |
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