毕业生知识库

      随着社会建设的不断发展，城镇化进程加快，大型建筑物的日益增多，伴随着移动智能设备，无线网络等高新科技的不断发展，人们对位置服务的需求日渐加强。商场里、地铁里、博物馆里室内定位的出现，让我们不用在复杂的建筑物里搞不清方向，在应急救援、公共安全、公共卫生、生产安全、特殊人群监护、大型场馆管理、智慧城市建设等领域都需要使用精确的室内定位信息，尤其是矿难、火灾、地震等各种自然灾难。

      当前室内定位技术研究方向呈现多元化，如基于移动通信网络的辅助全球定位系统GPS(A-GPS)、无线局域网（WLAN）中的Wi-Fi、Zigbee网络、iBeacon网络下的蓝牙(Bluetooth，BT)、超宽带(Ultra Wide Band，UWB)、RFID等无线通信技术。其中，UWB技术以具备优异的抗多径干扰性能，高时间分辨率和低功耗等特点成为室内精确定位方面学术界和产业界的研究热点。

      实际应用场景中，必然存在着多个定位节点动态变化的过程。本文围绕应用到达时间差（TDOA）定位算法的UWB精确定位系统，对应用于精确定位的UWB传感网络中的关键技术进行研究。无线传感网络中的媒体访问控制(MAC)协议可以有效地解决典型应用场景中网络内各节点的数据包冲突。UWB定位系统是以信号飞行到达时间为基准实现定位，现有的无线传感网络MAC层协议无法满足UWB传感网络定位系统的需要。

      针对以上情况，本文提出一种无冲突的邻居发现方法，并在UWB MAC层中进行实现。 本协议结合定位算法特点，能够适用于多节点动态变化和实时定位的场景，较好地达到了UWB传感网络定位系统的要求，保证了UWB超宽带精确定位网络性能。

      经仿真分析和平台验证表明，本文提出的MAC层邻居发现协议在充分贴合定位算法机制的基础上，能够有效地处理UWB传感网络定位系统中的数据包冲突，满足精确定位网络对动态性和实时性要求。

 

    With the development of the society and the accelerating urbanization process, the number of tall buildings is increasing. As the development of mobile smart devices and wireless networks technology, people's demand for location based service (LBS) is increasing. The emergence of the indoor positioning in the museum, mall and subway, making people aware of the directions in complex buildings. At the same time, we need to use accurate indoor positioning information.in public security, public health, safety, special crowd monitoring, large venue management, wisdom urban construction and other fields，especially the mine disaster, fire, earthquake and other natural disasters.

    Currently, research direction of indoor positioning technology is plural, such as the auxiliary GPS(A-GPS) based on mobile communication network, Wifi based on wireless local area network (WLAN), Zigbee network, Bluetooth based on beacon network, Bluetooth, BT), Ultra wideband radio (UWB), RFID, etc. Among these technology, ultra wideband radio (UWB) system becomes indoor high-precision positioning research focus in the academia and industry due to its high-performance resistance against multi-path interference, high temporal resolution and low power consumption.

    In practical application scenario, inevitably there are lots positioning nodes in the process of dynamic change. This paper focus on the high-precision positioning system based on Ultra wideband radio (UWB) using Time Difference of Arrival (TDOA) measurements, and study the key technology of UWB sensor networks. Media access control (MAC) protocol is responsible for detecting and avoiding data packet collisions in wireless sensor networks. However, because of the difference between UWB systems and traditional narrowband system, and real-time, dynamic characteristic of UWB positioning system, the existing wireless sensor network MAC protocols cannot meet the needs of the UWB precision positioning network.

    In view of the above situation, this paper proposes a collision free neighbor discovery protocol which can be implemented on UWB MAC layer. Combining with the characteristics of localization algorithm, the proposed protocol is suitable for multi-node, real-time of UWB positioning sensor network. Therefore, the protocol has reached the requirement of UWB precision positioning network, ensuring the ultra wideband (UWB) high precision positioning network performance. 

    Simulation analysis and hardware platform validation show that the proposed neighbor discovery protocol in MAC layer can effectively deal with positioning packet collisions in UWB high precision positioning network, satisfying the dynamic and real-time requirements of the network.