System architecture challenges in the home M2M network

Wireless home networks are extending beyond phones and computers to include every imaginable type of electronic device from TVs and audio components, to appliances and thermostats. The benefits include distribution of multimedia throughout the home, energy savings through remote or automatic control, and reduced cost through packaged services. Though people are often enamored by the technology that provides very broadband wireless streaming for multimedia, an important new class of low data rate machine-to-machine (M2M) devices are key to this highly connected home. The M2M device class is typically characterized by very low power consumption and little or no human intervention. In many cases, they autonomously communicate with each other or with a central controller. The home of the future will be outfitted with many such devices. Applications, such as home security sensing, lighting control, HVAC systems, appliances that run smart grid applications, medical devices, and entertainment systems, will all need to connect and communicate from within the home. There are many challenges in the design of the home M2M network. Varying security, power, and data rate requirements for M2M devices necessitate that they use different network protocols to communicate. The 802.15.4 (ZigBee/6LoWPAN) protocol is well suited for low power / low data rate applications such as HVAC control and appliances. The 802.11 (Wi-Fi) protocol works well for higher data rate applications such as audio and video streaming. Cellular is the best fit for applications that need to roam into and out of the home network. The Bluetooth protocol is well suited for low data rate communications such as audio connections and file transfer. The home network will require an M2M gateway to facilitate communication among the various devices and to provide a connection to a backhaul that reaches the Internet. The gateway can have many different embodiments; it needs to support one or more of the local network protocols as well as the back haul connection to the Internet. The backhaul connection may be Ethernet, cable, DSL, fiber, or cellular. As M2M gateways become more commonplace, they may be integrated into miniature cellular base stations, or femtocells. Femtocells will allow multiple devices (cellular and non-cellular) to access the Internet through an IP-based backhaul. This paper explores some of the many systems architecture challenges that are associated with the evolving home M2M network. In particular, the focus is on the design of the home M2M gateway and the challenges that arise when building a home network that utilizes multiple network protocols. Several questions need to be addressed. First, what protocols should be supported by the M2M gateway and how can the gateway best handle communication between nodes that use different protocols? Second, what data aggregation and dissemination techniques can the gateway use to assist low power/low duty cycle service requirements? Finally, can technologies, such as software defined radio (SDR), be used to build gateways that allow the user or operator to select what network protocols and air interfaces are supported?