基于物联网技术的智能家居系统

Smart home based on internet of things

本文结合物联网思想和多种无线传输技术设计了一种多功能智能家居系统.设计的系统由感知层、网络层和应用层三部分组成.感知层设备包括智能门禁、环境参数检测和家电控制,该层各设备均支持ZigBee协议通信.网络层包括ZigBee网络、控制终端和全球移动通讯系统/通用分组无线服务网络.控制终端与前端感知设备之间通过星型拓扑结构的ZigBee网络通信,前者作为协调器,后者作为普通半功能节点.应用层通过手机和全球移动通讯系统网络实现与用户的交互.当感知层设备检测到出现异常时,会通过Zigbee网络将异常信息发送至控制终端,终端再通过全球移动通讯系统网络将信息发送至用户手机.用户也可向控制终端发送短消息以实现对家电或安防设备的远程操作.由于全部采用无线通信,且全球移动通讯系统网络是我国覆盖面最广、最稳定的无线公网,因此本系统的安装方便、无需布线,即使在偏远地区同样能提供可靠服务.

Smart home system is now widely used in our houses,offices and etc.but those existing products are mostly wired,which causes inconvenient installation and high cost.Therefore we propose a wireless smart home system based on internet of things,which aims at expanding the range of network users from people to things,eventually making the automatic process of information transmission among things come true.In other words,things could communicate automatically.Our smart home system has a three-layer structure,which includes front-end sensor layer,network layer and user service layer.The sensor layer consists of entrance guard,environment monitors and household-appliance controllers,all these devices support ZigBee communication protocol.Household-appliance controllers are integrated into according remote controllers,in order not to modify appliance itself.The network layer consists of IEEE802.15.4(ZigBee),a control terminal and global system for mobile communications(GSM)/general packet radio service(GPRS).Control terminal is in charge of information gathering and distribution.A secure digital memory card is used to record every single event.The front-end sensors connect to the control terminal over ZigBee network in a star topology.The terminal plays the role of coordinator,which is a full-function device.And all the front-end sensors are normal reduced-function devices.Wireless ransceiver is performed by JN5139,which is a low power,low cost wireless microcontroller suitable for ZigBee.The user service layer provides human-device interactions.Terminal controller supports bidirectional communication with users over GSM/GPRS by integrating Siemens MC35i module,which is a supper slim dual-band GSM communication module;it supports standard attention command set.Records could be checked by using keyboard and liquid crystal display of terminal.The whole smart home system functions in this way: once front-end sensors detect anything unusual,they would notify the control terminal immediately over ZigBee network.After receiving a notification,the control terminal would parse it,and send a text or multimedia message to user's cell phone over GSM/GPRS network if necessary.In the opposite direction,if user wants to control a household appliance,the only thing he needs to do is to send a formatted text message to control terminal.After receiving and parsing the message,the control terminal understands user's intention correctly.Then terminal would send commands to corresponding household-appliance controller over ZigBee network.All communications in our smart home system are wireless,so there're no wires needed during installation.Human-device interactions are mostly done over the GSM network,which has the widest coverage in this country.This makes sure our system is able to provide high-quality service even in some remote regions.