Research on elemental Technologies for Communication and Broacasting Integrated Services

在本次研究中，我们提出了一种新型的信息平台，将移动通信系统和数字地面广播系统有效地融合在一起。下载链路采用UHF频段470~770 MHz的数字地面广播媒体，实现宽带传输。为了实现所提出的平台，我们重点研究了UHF频段的比特传播特性，以及平台上的高效数据分发方法，并在此基础上对UHF频段的无线电传播特性进行了研究。在室外测量中，采用了车载GPS和UHF频段接收机的测量系统。利用该测量系统，我们可以同时测量接收到的水平仪和定位数据。根据得到的数据，我们可以配置接收到的广岛市周边水平等高线地图。结合地形视线面积对接收到的水平等值线图进行评估，发现UHF频段的接收水平与地形视线面积有很高的相关性。另一方面，从室内测量的结果来看，利用无线电波从外而内进入，可以清楚地看出，在接收端存在着许多多径无线电波。多径波在接收电平中引起较大的衰落。为了解决这一问题，我们将分集技术应用到无线电波的接收中，阐明了分集技术可以在很大程度上改善衰落的水平；此外，在数据分发方法的研究中，我们提出了无线组播方法，可以将数据传输到使用无线电波的多个用户。实验结果表明，即使在单播业务共存于同一网络的情况下，该方法也能提高链路容量的分配效率。

In this investigation, we have proposed the new type of information platforms, where mobile communication systems and digital terrestrial broadcasting systems are effectively fused. The digital terrestrial broadcasting media using UHF band from 470 to 770 MHz is applied to the download link to achieve broadband transmissions. To realize the proposed platforms, we have focused on the ratio propagation characteristics in the UHF band, and the high effective data distribution method on the platforms in this investigation.The UHF band radio propagation characteristics have been investigated based on the measurement. In the outdoor measurement, we utilized the measurement systems using GPS and UHF band receiver configured on the vehicle. By use of this measurement system, we can simultaneously measure the received level and the positioning data. And from the derived these data, we can configure the received level contour map around Hiroshima city. Evaluating the received level contour map combined with the terrain LOS area, it is found that the received level in UHF band has a high correlation to the terrain LOS area. On the other hand, from the results of indoor measurement, using the radio wave enters from outside to inside, it is clarified that there are many multi-path of radio wave at the receiver. The multi-path waves cause the large fading in the received level. To solve this problem, we have applied the diversity technique to the reception of the radio wave, and clarified that the diversity technique can largely improve the level fading.Moreover, in the investigation of the data distribution method, we have proposed the wireless multicast method that can deliver the data to many users using radio waves. And it is found that the proposed method can improve distribution efficiency controlling the link capacity even if the unicast service coexists on the same networks.