蜂窝调制解调器利用现有的基础设施以降低通信开销

　　蜂窝调制解调器利用现有的基础设施以降低通信开销

　　在建立机器对机器（M2M）通信的基础设施时，系统将利用各种无线联网方案进行互联。然而，为了利用无线网络标准，如802.11（Wi-Fi）、ZigBee和其他数据网络标准，还必须安装额外的子系统，如接入点、路由器和其他与网络相关的硬件。对于设计者来说，使用数据网络在M2M网络上发送数据是可行的选择，这就是已经安装的蜂窝电话网络。在许多情况下，Wi-Fi或ZigBee等数据网络产品，甚至专有的解决方案可以通过收集来自附近M2M设备的数据，然后将其聚合起来，与蜂窝网络协同工作。聚合数据然后通过蜂窝网络发送到中央主机位置。

　　Therefore， rather than install a dedicated， on-all-the-time Ethernet connection that could continuously send data back to the central system， a cellular system can be set to send data on a regular schedule in short or long bursts， depending on the amount of data and the throughput of the cellular connection. Each of the connected devices， vending machines， medical equipment， smart appliances， utility networks， industrial systems， and others could have a cellular modem if they are not in close proximity to each other. When several devices are relatively close， using short-range data networking such as ZigBee， Bluetooth， Wi-Fi， or other wireless interface to send data to a local aggregation point could reduce the hardware costs. Once data is aggregated， a cellular modem can be used to transfer the data to the host system using one of the many cellular standards （GSM， EDGE， HSPA， LTE， and more， Figure 1）。 As costs come down for cellular modems， each device in the field could be fitted with its own modem.