“Growth in machine-to-machine (M2M) connections is now far outpacing new connections between people, and there will soon be far more machines than people connected via cellular networks, as predicted by the GSM Association in Figure 1. Show. These machines include security systems, meters, robots, vending stations, asset trackers and emergency call systems. The variety is growing, with millions of machines exchanging data 24 hours a day, 7 days a week, without human intervention, and silent conversations.
Authors: Thomas Nigg, Stefano Moioli
When choosing a wireless modem, there are a number of features to consider. We cover these here.
Growth in machine-to-machine (M2M) connections is now far outpacing new connections between people, and there will soon be far more machines than people connected via cellular networks, as predicted by the GSM Association in Figure 1. Show. These machines include security systems, meters, robots, vending stations, asset trackers and emergency call systems. The variety is growing, with millions of machines exchanging data 24 hours a day, 7 days a week, without human intervention, and silent conversations.
Figure 1: Growth of M2M communications.
At the same time, connecting to the internet has become cheaper and easier, and even mass-produced computing devices are capable of collecting and processing ever-increasing amounts of data. With the introduction of IP version 6 (IPv6), a potential bottleneck for the more than 4 billion IP version 4 (IPv4) addresses that have been allocated is a potential bottleneck for larger M2M connections. This supports 2128 addresses, enough for every grain of sand on the planet to have its own. So it’s perhaps no surprise that the fourth generation of mobile networks (4G), LTE, is designed to provide services such as data, voice, and video over IPv6.
To join the M2M networking revolution, simply embed a small, economical (wireless) modem in the machine. Machines also need a GPS or GNSS (Global Navigation Satellite System) receiver where position, speed or navigation information needs to be established. Both components with antennas can easily fit in devices smaller than a cell phone. GNSS is the standard generic term for satellite navigation systems that provide autonomous geospatial positioning with global coverage. It includes GPS (USA), GLONASS (Russia), Galileo (Europe), Beidou (China) and other regional systems.
When considering how to equip a machine with communication capabilities, the first thing to consider is the needs of the application. Product longevity, geographic network coverage, or future-proofing considerations for future wireless network upgrades are all important considerations. Here are some product features to consider when choosing a wireless modem.
Battery life matters
The time between battery charges or replacements is critical to the success of some products. For example, a tracking device mounted on a container may take days if shipped by air or road, or weeks if shipped by sea. Battery life must be sufficient to support these timescales.
Phones typically run for two to three days on a charge. As a result, consumer expectations for the longevity of health and fitness equipment will be similar. Active and standby current consumption and power saving features are important when comparing modem and GNSS receiver specifications in these applications. The latter may include automatic wake-up capabilities and smart power-saving modes, such as the ability to autonomously log data without waking up the host processor. Ideally, components should only wake up when needed.
Mobility requires multi-standard compliance
The global mobility of people and goods is increasing, so it’s important to consider where modems need to work today and where they may need to work in the future. GSM is supported by four major frequency bands worldwide, UMTS is supported by six frequency bands and LTE is supported by more than 30 frequency bands. Electricity meters are usually static, while resource management systems may need to work in all regions of the world and should include quad- or dual-band GSM modems (depending on location) or six-band UMTS modems.
Certified modems to expedite product approvals
Any cellular network equipment, whether for GSM, UMTS or LTE, requires regulatory, industry and operator certification. If the modem embedded in the device is certified, it significantly simplifies and speeds up the certification process.
What you need today may be different tomorrow
While GSM/GPRS networks are fully capable of handling the small amounts of data transmitted in remote metering applications, GSM frequency bands have been considered for reallocation for 3G and 4G services. To save future-proofing costs, it is a good idea to design with future technical standards in mind. Today, that means designing with UMTS/HSPA or LTE modems, or at least using future-proof hardware to simplify upgrades.
Nested Design Simplifies Technology Upgrades
Cellular M2M technology is constantly evolving, and when designing new devices that support cellular connectivity, it is important to consider that they can be upgraded to newer technologies to optimize design costs. Here, there is layout compatibility for the entire range of cellular modems (GSM, UMTS, CDMA and LTE). With this approach, one PCB layout can be used for all end product variations, ensuring easy migration between cellular technologies and module generations, also thanks to AT command compatibility within different modules.
Bandwidth requirements are rarely reduced
Tracking an application’s bandwidth needs only goes in one direction — upward — so it’s important to consider the lifetime cost of a connection. Choose a modem based on what it’s likely to do in three to five years, or at least one that’s easy to upgrade.
Special needs for cars
In in-vehicle systems, temperature, humidity and vibration can be extreme. AEC-Q100 qualified equipment manufactured in an ISO/TS 16949 certified facility will ensure reliable, long-life operation. The qualification test for each component shall be in accordance with ISO16750, Road vehicles – Environmental conditions and tests for electrical and Electronic equipment. This applies to on-board and industrial equipment operating in harsh environments, such as ships or rail cars.
Emergency call systems are growing in popularity
More and more cars are equipped with systems that automatically report accidents or aid in recovery after theft. The United States, Europe, Russia, and Brazil already have plans to support such systems, and government mandates will increasingly require them. For these applications, an “in-band modem” is usually required. It sends data over a modem voice channel in the same way a fax machine sends data over a telephone line. This is necessary because carriers prioritize voice over data in mobile networks. In the event of an accident, the voice channel becomes a critical link in transmitting data to emergency services. Check if the suggested solution supports in-band modems on 2G and 3G networks.
Assisted localization in urban environments
In urban environments where satellites may be blocked by tall buildings, the loss of the location overview can be overcome by invoking a remote A-GPS server. This simple process uses a wireless modem to download a few bytes of satellite orbit data from the Internet. With this assistance data, visible satellites only need to be visible for a few seconds to calculate position, rather than the full 30 seconds required to receive the entire 1,500-bit satellite frame.
Check if the GPS receiver vendor offers online help with guaranteed availability and that covers the geographic area of interest. Client software should transparently support this service, and both the positioning receiver and the wireless modem should have an interface to support this service. It is also increasingly important that the service be available for GPS and GLONASS.
Dead reckoning supports inferring positioning data from sensors
Satellite signals can be supplemented with dead reckoning support to infer position and velocity from data from vehicle sensors, as shown in Figure 4. This method helps determine the location of the vehicle in tunnels or other locations where satellite reception is temporarily unavailable. It is useful in vehicle-based telematics, including insurance tracking systems, which accurately record position, heading, and speed.
Figure 4: Dead reckoning infers position data from vehicle sensors, including gyroscopes and wheel scale sensors.
Check that the positioning receiver is automotive grade, supports dead reckoning, and can be plugged into the vehicle’s CAN bus to get data. Additionally, ensure they can interface directly with vehicle sensors such as gyroscopes and odometers, and that suppliers provide an evaluation environment to accelerate product development.
Indoor positioning is possible by combining satellite and cellular data
Combining a satellite receiver with a wireless modem can overcome the problem of satellite signals being blocked by walls or other obstacles in situations where an approximate indoor location needs to be determined. This hybrid solution takes advantage of the visibility of 2G or 3G cells, as GSM or UMTS signals can easily penetrate walls. The approximate location can be calculated by knowing where the cells overlap, knowing the boundaries of the visible mobile cells. This approach requires a wireless connection to an external service, similar to assisted positioning. Check if the positioning receiver and wireless modem supplier can provide such a solution and it is verified and available online. It is also important to ensure the accuracy of the system.
Positioning System Compatibility
Until recently, GPS was the only concern for system designers. Now, there are GLONASS in Russia, QZSS in Japan, Beidou in China and Galileo in Europe. Compatibility with GPS and at least one other satellite system will be required to improve the reliability and accuracy of the system and to fulfill the task of local governments being compatible with their own systems. Parallel operation using both systems at the same time may be part of the specification. An example is Russia’s new ERA-GLONASS vehicle emergency call system, which needs to be compatible with GLONASS. Look for GPS/GNSS receivers that offer multi-GNSS support and offer parallel GPS/GLONASS or GPS/Beidou reception.
These are just some of the considerations when adding wireless connectivity to M2M products. Remember that many new standards such as wireless and positioning are transitioning. It is important to consider how the product will operate during its life cycle and which markets it will serve. Also, consider whether it is important to include design support for next-generation performance and network coverage, or to choose designs that allow for easy product upgrades in the field.
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