关键词：汽车；通讯；无线通讯；软件程序；移动卫星服务
摘 要：The Global System for Mobile Communications (GSM) Association predicts that there will be nearly 50 billion connected devices by 2025, nearly ten times the worlds predicted human population. ABI estimates that through 2012, Machine-to-Machine connected devices will grow by 100m units per year by 2012.1 An M2M module uses a device to capture an event (temperature, activation of airbags, etc.), which is relayed through a network, either wireless or wired, to an application, such as a software program, that translates the captured event into meaningful information (e.g., ice warning, crash notification). An M2M device typically converts analog sensor data into internet protocol (IP) packets for transmission over a communications medium. M2M applications are often characterized by the absence of a human decision maker directly controlling communications intensity, frequency and costs, though there are M2M applications in the transportation sector that also require interaction with drivers. M2M devices can be transmitted over a variety of communications mediums including mobile satellite services, cellular networks, and even combinations of carriers and carrier coverage areas across several networks. Hybrid wireless solutions include intermediary devices such as cellular modems connected to an M2M endpoint via wireless local, personal area or near field communications networks such as Wi-Fi, ZigBee, Bluetooth or Radio Frequency Identification (RFID). The most common communications system for M2M in use today in North America is second generation (2G) wireless, using either General Packet Radio Service (GPRS) or Short Message Service (SMS), which uses signaling protocols that set up and tear down voice calls to transmit small amounts of data.