RTC Magazine

In machine-to-machine (M2M) communications, a field-deployed wireless device gathers data and sends it to a back-end server through a wireless network. M2M is particularly useful in the transportation industry, where valuable data provided in real time can ensure a smooth transition for goods or passengers.

The goal of any passenger train service, trucking company or bus service is to move goods or passengers from point A to point B in a pleasant and efficient manner. M2M has emerged as the next-generation technology that can smooth transportation by allowing for real-time data analysis. For instance, M2M communication allows a bus station to update arrival and departure times based on data provided directly from the bus fleet. M2M communication also allows a grocery supplier to monitor the temperature for frozen foods on a semi-trailer truck.

Mobile computing platforms have become smarter and the number of applications requiring complex, real-time data is growing. There is a wide range of unique transportation markets including rail, commuter bus, fleet and air, and several key factors come into play when considering the product development lifecycle for M2M devices in transportation (Figure 1).  Regardless of the end application, product designers must carefully consider similar basic requirements: communications, I/O, packaging, operating system and networking.

Communications

The most important aspect of the M2M system for smooth transportation is connectivity for reliable communications. It is critical to identify the wireless capabilities of the M2M device, including: cellular (GSM/GPRS & CDMA), 802.11 (access point, client only), satellite, GPS, Bluetooth (class 1 or 2), mesh networking (ZigBee, 802.15.4, 6Lopan), RFID and others.

Each wireless interface has several specifications to consider in choosing the correct hardware path. Cellular is the most prevalent and essential hurdle to overcome to successfully deploy a new product with an M2M application. The correct cellular design leads to long product life cycles and improved sales. Making a mistake leads to redesigns and expensive certifications that delay time-to-market.  

Consider the following options for cellular communication:

• Technology 
• - High Speed – 3G, 4G (EvDO, HSDPA/UMTS)
• - Low Speed – GPRS, iDEN, 1xRTT CDMA
• - Market/Carriers  – Verizon, AT&T, Sprint, Global, others
• Interface
• - Standard – Pluggable Module (USB, Cardbus, Serial), Mini PCI, Mini PCI Express
• - Custom – Typically a 40+ size pin header
• Certifications
• - Carrier Certification
• - CE, FCC
• - PCTRB
• - CTIA

Matching the right technology speed and cellular carrier enables a transportation company to take a focused approach to going to market with their M2M application. For example, if the application is GPS tracking and engine diagnostics with simple I/O, high-speed network connectivity might not be necessary. A lower-priced GPRS device should do the trick. However, if the application will use Wi-Fi, digital signage and Internet access for peripheral devices such as a PDA, it is critical to achieve the highest possible speed and 3G technology is the best avenue.

Choosing the right interface for communications support depends on the carrier and technology speed. For the 3G network, a modular approach with a Mini PCI Express card typically allows for the most flexibility, highest speeds and works on almost all carriers. As new technologies are offered with higher connectivity speeds, these modules can be updated fairly quickly and allow for short implementation cycles to get to market. Planners must keep industrial temperatures in mind. High-speed modules do not usually have a -40° to +85°C temperature range, but they are generally rugged enough for most situations. For a lower speed product, use a module provider that offers long-term product lifecycle support. The technology is already outdated, so make sure you have at least 5 years of support for any given device architecture.

System designers should consider the certification process at the beginning of the product development lifecycle, since it is sometimes the limiting factor to putting a product on the market. In the United States and some other countries, cellular carriers require certification for each cellular product on their network prior to deployment. Therefore, after all of the hardware and software development, RF tests, packaging and documentation, each product must go to each carrier for certification. The certification process can be expensive and can delay deployment by as many as nine months. If there are issues that require a redesign, the added delay could kill the product. Planners do well to work with carriers early in the development process to receive guidance and eliminate problems before they occur. 

I/O & Packaging

The M2M market for transportation is applied widely and has varied requirements. There are two common approaches to hardware design: fit-for-purpose or a modular platform. Fit-for-purpose systems are designed to meet an application’s requirements with little change, such as asset tracking requiring power, GPS and cellular connectivity. A modular platform is designed to meet the requirements of many applications across different segments within the transportation industry. For either choice, there are several components worth exploring during planning and development.

Power consumption is relevant for applications requiring continual connectivity, even when the vehicle is not running. If the embedded device will always be on, the power consumption needs to be 20 mA or less. Low power is achieved by processor choice and the ability to put hardware components into a sleep mode. For applications that operate only when the vehicle is running, low power consumption is not as critical. Some devices will need to be powered for a fixed amount of time after the vehicle shuts down to upload data at a hotspot requiring additional hardware.

There are many types of vehicles that service the M2M transportation market, and there are just as many ways to provide power. While there are no set standards for input voltage, there are some similarities in each segment. Most designers target a wide range encompassing the maximum number of applications such as those typically seen in Fleet platforms with an 8-36 VDC input. The examples below detail the typical requirements recommended for design:

• Fleet – 12 or 24 VDC

• Rail – 12, 24, 48, 72, 120 VDC

• Air – 12, 14, 24, 28 VDC

 There is need of new technology in terms of the ability to survive the commonly encountered transients or surge voltages in the automotive environment. The platform designer must ensure reliable circuit operation in this severe transient environment. The transients range from the severe, high-energy transients generated by the alternator/regulator system to the low-level “noise” generated by the ignition system and various accessories, which can be detrimental to poorly designed products. It is critical to provide transient surge protection for the hardware based upon the application. For most vehicle applications the transient protection needs to be from 100 to 150V to shield the hardware from failure. The protection enables the device to connect directly to the vehicle bus for ease of installation and provides longevity to the hardware design.

Not all applications for transportation devices will require isolation and it can be an expensive capability to add. However, it is a must in most rail applications. There is no ground available in rail applications due to the fact that the device is running on rail, which is commonly known as a floating ground. In this environment it is possible to encounter large differentials in power and the device must act in complete isolation as an autonomous system protecting the hardware inputs, chassis and antenna connections. The typical range of isolation is 1000 to 2500V on the various I/O.

Antennas are significant for a well connected device and smooth customer experience. Antennas are either integrated or external to the product. Radio frequency experts should handle integrating the antenna into the device as the composite of the enclosure and placement needs to be carefully engineered. For all external antennas, less engineering is required but planners must be aware of the type of connector required and the specific needs of the radio frequency device. For example, the 3G network modules are typically enabled with two antenna connections, one for main and the other for diversity. It is not a requirement to have both, but may be necessary for certain applications.  

The transportation market requires a rugged design for the vertical markets such as rail, air and military projects since they require certification. The packaging should not be an afterthought but rather considered throughout the lifecycle of the design. Each application can have unique standards though it is typical just to meet SAE J1455 or MIL-810-F shock and vibrations standards for most fleet applications. Wide temperature ranges, fan-less requirements and compact size constraints are also common considerations during package design.  

Operating System & Networking 

M2M systems in transportation are continually dropping on and off the network, requiring belts and suspenders in the code and operating system to maintain the connectivity and reliability.  Running several wired and wireless networks in a mobile platform is not easy and requires complete control of the interface, which also includes the application being able to support the interrupts. Designing the application in a clean environment and expecting it to run on a mobile platform ignorant of communications is not likely to be successful or sustainable over time. Also, keep in mind that planners must focus on driver support for the peripherals and internal modules since they are major contributors to the success of the project. 

One of the most important aspects of a platform is its routing capabilities to connect multiple network interfaces from backend applications. To connect to peripherals through serial ports, mesh networking, Ethernet or USB interfaces requires tooling that is easily enabled and controlled. The routing functionalities that are important include Mobile IP, network address translation (NAT), port-forwarding or masquerading, terminal server and clients, DHCP client and server, and static routing.  

Since most of the devices are connected to the Internet, data security is a must. Operating and connecting secure devices in mobile applications includes understanding the following topologies/technologies:

• VPN – IPSec, OpenVPN...
• SHH, SLL 
• Routing, Port-forwarding and Network Address Translation (NAT)
• Encryption – AES, Blowfish, 3DES...
• WEP, TKIP, WPA…

 Technology and firewalling are essential for device connectivity of data between backend applications and other data consumers. Protecting the device from malicious hacking and securing the network connectivity is always a concern.  

Managing the mobile computing platform with firmware updates and programs additions on a moving asset is part of M2M. These updates can be difficult if the OS and application do not have the correct tooling. An OSGi application framework is ideal, allowing for bundles of Java code to be deployed, stopped, started and rolled back with version control. Providing diagnostic tools for logging and debugging allows bug fixes and application issues to be handled remotely and not through costly removal of the hardware, inherently saving time and money.

Providing Accurate Passenger Data

Integrated into the other functions of an M2M transportation system is the collection of passenger data, which can be used separately or correlated with other data in the control center. Transportation agencies need to count passengers for three reasons. First, they need to report passenger counts for government subsidies and budgeting. Second, they want to know how many people are riding compared to how many fares they are collecting. Third, they want to know how many people are riding to monitor and smooth schedules and service offerings 

Prior to the latest embedded systems and M2M technology, drivers counted passengers with a clicker. Drivers have to focus on safety and driving, of course, and counting passengers is last on their list of responsibilities. Counting by hand is only about 70 percent accurate.

Now, a remotely fielded embedded device automatically counts the number of passengers and reports the count in real time to a server. The data is collected and agencies use the information to better manage fleet operations and scheduling. The analysis of the data provides a better overall customer experience and increases fleet utilization managing costs while increasing profits.  

Successful machine-to-machine hardware design smoothes transportation for both users and operators. Data is moving quickly on rail, ground and air fleets, and embedded systems allow operators and backend applications to pull data off these moving parts and synthesize the information in real time. With the right design and focus on communications, successful delivery of data into M2M applications is possible. 

Eurotech.
Columbia, MD.
(301) 490-4007.
[www.eurotech.com].