032-033-034_EETE-VF

EETE SEPT 2013

TEST & MEASUREMENT Advanced verification for fault-free wireless M2M communication By Franz-Josef Dahmen M2M (machine-to-machine) communication brings valuable benefits both to device manufacturers and to end users: remote sensing, monitoring, tracking and data-logging bring a new dimension to the functions of machines in industrial, commercial, military and other market segments, in applications such as automation, vending, smart metering and logistics. Wireless is the preferred mode of communication for nearly all these applications. Of course, wireless communication supports mobile applications, such as track-and-trace in the logistics sector. But even in fixed devices, wireless connectivity is often preferred because of the low cost of installation, particularly in remote locations, and the ready availability of commercial off-the-shelf communications modules for wireless protocols such as GSM, 3G and LTE (in cellular telephony), as well as ZigBee and WiFi. With mobile telephone network reception now available almost anywhere in the world, cellular telephony provides the greatest flexibility and coverage Fig. 1: The SmartStudio software provides an intuitive interface to guide the user through the development of a test case. for device manufacturers implementing M2M communication (also known as MTC – Machine Type Communications). But in many cases, this will mark a development team’s first engagement with the sometimes perplexing field of radio. And simply bolting a GSM or 3G module on to an existing end product is no guarantee of effective wireless connectivity, no matter how good the module is. This article shows how modern simulation techniques can be used to verify the performance of an M2M or MTC application during product development, so that manufacturers can be confident it will work faultlessly when it is released into the field. The components to be tested A simplified M2M system architecture consists of three elements: the M2M application itself (the host), the communication/wireless network, and the M2M device (normally a modem). The operation and interactions of these three elements determine the reliability of an M2M system. The operation of the network is, of course, outside the device manufacturer’s control. But the choice of network type is important, because network availability in the expected locations of use is a prerequisite of reliable connectivity. In fact, most countries in the world now have almost total wireless network coverage in some form. The densest coverage is normally through 2G networks, such as the GSM/GPRS networks introduced Fig. 2: Testing an M2M device’s cell selection capability on a network simulator. in the early 90s in Europe and Asia. Beginning in 2000, 3G networks (using WCDMA, CDMA2000 or TD-SCDMA technologies) were built out in parallel to the existing 2G networks. Today, we are seeing the roll-out of 4G LTE networks, which provide an always-on, broadband wireless connection to the internet. 2G networks offer circuit-switched and packet-switched access to the user domain. Of the varieties of 2G technology, GPRS, which offers higher uplink and downlink data rates than GSM, is currently the most widely used for M2M data. For some applications requiring the transfer of only small amounts of data, Short Message Service (SMS) is also sometimes used. This choice of widely available network topologies provides a strong and stable foundation for the development of wireless M2M functionality. But although wireless networks might be available almost everywhere, access to them can differ from area to area and from time to time, because it depends in part Franz-Josef Dahmen is Field Applications Engineer at Anritsu GmbH - www.anritsu.com 32 Electronic Engineering Times Europe September 2013 www.electronics-eetimes.com


EETE SEPT 2013
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