Mesh Technology Knits Tighter, More Flexible Mine Communication Networks
The latest mesh networking systems offer faster throughput, higher reliability, almost unlimited scalability—and the potential for saving millions in mine operational costs
By Russell A. Carter, Managing Editor
In certain respects, a modern surface mine has some of the same characteristics as a battlefield—people and machines are constantly on the move, the topography can be complex and changeable, and there is ever-present danger from explosions, unintended encounters with massive mobile machinery, and other hazards such as fires originating from high-voltage electrical or highly pressurized hydraulic systems, for example.
So, it’s no surprise that today’s state-of-the-art mine-site communications systems are designed around a wireless networking concept developed for the military that allows a network to automatically form, adapt, expand and even fix itself to maintain reliable voice and data communications under fluid and often adverse conditions. The concept, originally called “mobile ad hoc” communications, now more commonly known as mesh networking, has opened new avenues for mine operators to extend the scope and effectiveness of their site-wide voice, data and video transmission capabilities. In a wireless mesh network, nodes (devices) automatically locate one another and quickly establish a network without operator intervention. A node can send and receive messages, and in a mesh network, a node also functions as a router and can relay messages for its neighbors. The more nodes, the more resilient the network becomes, as each node adds to network capacity.
Wireless networking technology for mining applications generally falls into two broad schemes: Systems can employ a standards-based architecture encompassing one or more of the 802.11x Wi-Fi wireless protocols and using mostly off-the-shelf client devices; or they can be designed with proprietary technology—such as Mobility Enhanced Access, a platform for military-grade communications performance in harsh exterior environments. It’s not uncommon, however, to combine both types in a hybrid network setup that takes advantage of each technology’s strong points to solve an operation’s unique communications requirements.
As with cellular phone service, mesh networking has progressed through several stages or generations, with each generational advance leading to better network performance. In the earliest mesh systems, one radio or channel was used in network access points for both client servicing (traffic to all the various devices connected using the network, and for backhaul (routing traffic back to a fixed or satellite link). This configuration resulted in stop-and-go behavior as the radio listens for traffic, transmits and then listens again.
Second-generation mesh systems employ a two-radio setup—one dedicated to servicing client devices and the other to backhaul—and these radios generally use different frequency bands (2.4Ghz and 5 GHz, for example) for each task to improve efficiency. However, signal congestion can still occur, particularly in the backhaul path. Third-generation systems often use a three-radio setup with two identical radios handling backhaul and the third handling client service. The system actively manages channel assignments to avoid congestion or interference.
The advantages offered by a reliable, well-performing network are numerous. They include:
Productivity – High bandwidth communications systems allow users to maximize the value of their voice and data communications investment, enabling machine health monitoring and process control systems to report problems in real time, extending the reach and accessibility of mine management system reporting and analysis, and allowing better control and awareness of asset usage and availability.
Data-handling capacity – Careful planning can allow a network to serve a steadily growing arsenal of programs, systems and equipment, ranging from bandwidth-hogging CCTV video—for security, process monitoring and operator surveillance purposes, among others—to functions such as worker and equipment tracking, emergency response, proximity detection and collision avoidance, autonomous machine operation, truck dispatch systems, machine health monitoring packages, computer-assisted guidance for bulldozers, excavators and drills, overland conveyor and stacker systems, and office desktop software.
Expansion capabilities – Rarely does a large surface mine stay in the exact same configuration for more than a day or two—if for that long. Machines are reassigned, added to the fleet or taken out of service; new areas are opened to mining as other areas close; and leach heaps, stockpiles and dumps constantly change their physical parameters. Without sophisticated communications technology, these changes could make a mine network “flap,” operating in a constant state of flux leading to increased latency, interrupted voice communications and lost data.
Flexibility – As mining continues to expand into remote areas with little or no local infrastructure, the need for a quickly installable, reliable and easily maintainable communications system becomes acute—not just for the mining and processing operations, but also for the construction and mining camps and towns that accompany many of today’s greenfield mine projects. With workers expecting more home-like conditions and comfort, including a growing number of digital amenities such as wireless Internet access, the demand for expandable and economical site networking takes on another dimension.
The increased sophistication of satellite communications systems, the relative ease of interfacing a Wi-Fi or hybrid wireless site network to a satcomm backbone, and even the availability of increasingly efficient solar panels, for example, enable even the most remote mining operations to now have the luxury—if desired—of specifying and obtaining the bandwidth, data and voice comm security and other service options they require, right down to provision of “raw” Internet feeds for personal access. These systems can be tied into a corporate IT system for additional convenience, and a single on-site satellite backbone can usually be configured to provide segregated, secure communications capability for all of the various entities that might be present on a large project. Wireless mesh networks also can be configured to provide multiple Virtual Private Networks (VPNs) for additional security and convenience.
Focus First on ROI
For a mining company seeking to install or upgrade their site communications network, the long list of issues and choices involved in specifying, implementing and maintaining a satisfactory system can be confusing. At Mining Media’s 2009 Haulage & Loading Conference, held in May in Phoenix, Arizona, Greg Bazar, senior technology officer and vice-president of sales for communications equipment provider 3D-P, offered practical advice for prioritizing specific wireless mesh network issues.
“First of all,” Bazar warned, “just because you might be able to afford to install a big, 500-gigabyte pipe, doesn’t mean you should. Think about the application priorities involved. My favorite analogy is ‘don’t mix sewage with drinking water.’ Do you want your critical application data competing with [data from] a truck driver with a laptop on break, surfing the Web for who knows what?”
Bazar recommended breaking the decision process down to a few major steps. “Design your network with ROI [return on investment] as the primary focus. Define your high value applications—which ones are making money for you? Is your dispatch system giving you 15% better operational efficiency, or your machine health apps reducing your operational and maintenance costs?”
Once these high-ROI applications are identified, think about future developments. “Suppose you’re looking at autonomous machine operation. Will this be handled by your dispatch system, for example, or will it be an OEM-provided system? How will your network system handle this? Do you want extensive video coverage? If so, plan in advance to include the network capacity to handle this—video uses a lot of bandwidth.”
Bazar used the “magic triangle” to illustrate how the tradeoffs in network performance dictate system design. As shown in the accompanying diagram, throughput, range and reliability are the primary desired performance characteristics in any network—but it’s difficult to have all three. “Pick any two,” said Bazar. “About the only way to overcome this limitation is to have a very large number of nodes in the network.”
“Also,” he noted, “check the scalability of your applications on a wireless network. First of all, will an app actually work with a wireless network? And, just because an application works well with ten pieces of equipment, for example, doesn’t mean it’ll do as well when it has to handle 50 pieces. And how does the application transmit data—does it send packets continuously or ‘squirt’ them in bunches?”
When it comes to choosing hardware, Bazar said selection should be based on site-specific needs and conditions. “Are there mines right next door to you that are using the same radios you plan to buy? Think about possible interference. Which frequency spectrum(s) are available in your area?” Use of the Wi-Fi frequency spectrums doesn’t require a license, but it’s possible that licensed wireless technology available in a specific area—such as WiMax, for example—might offer a better solution.
Once these issues are identified, he said, take a look at the bigger picture: Can this system likely be implemented in accordance with your schedule and budget? What sort of upgrade path is available? What is the Mean Time Between Failure (MTBF) rating for the equipment, and can it stand up to local conditions? “Can the towers and equipment survive eighty-mile-an-hour winds?”
And finally: “Who will maintain the system? Keep in mind that mining lags behind other industries in IT investment. The average Fortune 1000 company, for example, typically IT invests 3-4% of revenue in IT—mining, less than 1%.” He explained that although some larger companies have tasked their IT groups to maintain network operation down to the tower level, that kind of support may be absent in smaller enterprises.” We like to say that ‘IT guys don’t have steel toes.’ You may have trouble getting them to come out to the site at 3:00 AM.”
3D-P, based in Scottsdale, Arizona, and with a manufacturing facility in Calgary, Alberta, Canada, and several international offices, has been in the communications business since 1996, starting out as a reseller of drill monitoring systems and moving to a main focus on wireless communications around 2004. The company builds a line of rugged, wireless Intelligent Endpoints, or modems, that are designed to support multiple systems—ranging from industry-standard mine optimization, machine health, grade and ore control and drill monitoring systems, to slope monitoring, GPS/GLONASS, video and VoIP—from a common hardware platform. According to the company, Intelligent Endpoints can be configured to connect with any physical layer protocol: Ethernet, RS-232/422/485, CAN, digital and analog signals. “We like to describe our products as the Swiss Army knife of communications,” Bazar explained. “They allow us to connect any piece of equipment to any radio network.”
Overcoming the Environment
3D-P is a business partner of Motorola, one of the largest providers of industrial-grade communications solutions, and has installed a number of mine communications systems using Motorola’s Mesh Wide Area Network (MWAN) Solo (6300 series) and Duo (4300 series) wireless networking products. Scott Garlington, senior product manager for Motorola’s wireless mesh networks product group, talked about Motorola’s technological approach for meeting the demands of mine-site wireless communications. “Mine sites differ from other industrial environments primarily because of the topography—usually involving an open pit—and in the size of the equipment and the large amount of metal in these machines. Both of these factors can contribute to multipath distortion as the radio signals bounce off pit walls or large machines. You have to have a radio that can handle these conditions.”
Matt Ward, also a product manager for Motorola’s mesh networks business, argues that “You cannot simply take an off the shelf WiFi product and place it in a mine environment to get what we would consider a connection reliable enough to allow that mine to make money.”
Ward noted that Motorola’s Solo is a purpose-built mesh technology for industrial applications with unique benefits for these environments. Dynamic Frequency Assignment enables the Solo network to use multiple channels across the unlicensed 2.4GHz spectrum to communicate. Solo also features Client Router Architecture, which extends and strengthens network coverage as each subscriber is a fully capable router/ repeater. Remote equipment can hop through other subscribers to reach the network infrastructure. Solo’s MEA (Mobility Enabled Access) waveform is designed to handle tough RF environments such as mining that present fast moving, high multipath situations.
One of the system’s strong points, said Garlington, is its ability to select the best channel on a packet-by-packet basis to automatically avoid interference and congestion. “In a large mine, we generally see about 200 devices maximum. But as robotics and other future applications are adopted, it’s likely that we’ll see as many as 500 or 600 devices in a large mine. At that point, the density of devices in a given space can become a problem, leading to congestion. The MWAN system is able to scale to meet those demands. By adding more backhaul links, you can quickly add 30 to 40 mesh devices per link and easily grow your network.”
“Data integrity throughout the network is another important consideration,” said Ward. “Video applications are certainly driving greater bandwidth requirements, while telemetry and other data streams typically take much less bandwidth. But there’s almost an inverse relationship in priority—if the system drops a frame or two of video, the user most likely won’t even notice it. But mission-critical data isn’t a steady stream, it’s sent in packets and you must have adaptive systems to ensure those packets reach their destination intact.”
“In a mesh network, the magic is in the software,” Ward explained. “We’ve designed the Solo system so that a packet that encounters interference can be re-sent, or sent over a different channel or in a different time slot so that, regardless of what’s happening in the mine environment, it will reach its destination.”
Echoing Greg Bazar’s recommendations, he suggested that a mine network should be set up to provide separate virtual networks for video, voice and data. In addition to the MEA-enhanced Solo product line, Motorola also offers a standards-based 802.11x system, MWAN Duo, which can be used for less mission-critical applications, such as video surveillance from around the pit, etc.
Garlington said Motorola will begin to introduce a product line of mesh access points, modems, and other devices that will take advantage of the newer 802.11n protocol, designed to provide higher bandwidth and to reduce multipath distortion—in fact, the system will use multipath to its advantage in providing a more robust signal. The introduction will start with system access point units available this fall, and with vehicle-mounted units becoming available early in 2010.
Communicating in Copper
Outfitting any large surface mine with a wireless mesh network is a major undertaking, but when the mine is one of the biggest in the world, the task can be daunting. Rajant Corp., a Malvern, Pennsylvania, USA-based developer and vendor of wireless mesh network technology, faced this type of challenge when it was selected to provide Rio Tinto’s Kennecott Utah Copper subsidiary with a primary communications platform for operations within the company’s Bingham Canyon copper mine.
At Bingham Canyon, mining operations run non-stop throughout a pit that measures 2.5 miles across and 1 mile deep. The farthest dump site is 6.4 miles from the pit. Kennecott Utah Copper wanted a wireless network setup to manage and control 85, 300–ton haul trucks, 12 shovels, and 62 pieces of auxiliary gear (dozers, graders, backhoes, stemmers, water/fuel/cable trucks)—and it wanted a system that would include only a small number of fixed wireless nodes, that would be able to connect hundreds of devices and grow the network on demand, and that would not allow changes anywhere in the network to disrupt the rest of the network.
A mine the size and complexity of Bingham Canyon might be expected to use a broad range of critical applications across its network, and that was exactly the case encountered by Rajant. Major applications employed by Bingham Canyon, and requiring a stable network that could handle a wide range of application-specific characteristics, included:
- Modular MineCare – Equipment health monitoring and maintenance system
- Modular Dispatch – provides optimized haul truck assignments, GPS-based equipment positioning, equipment health monitoring, maintenance tracking & blending
- Caterpillar Aquila – Drill Management System
- Caterpillar CAES – (Computer Aided Earthmoving System) optimizes excavation equipment
- performance for precise grade and slope control.
- Caterpillar VIMS – (Vital Information Management System) provides a wide range of vital machine functions.
- Komatsu VHMS Communicator – (Vehicle Health Monitoring System) provides the means to
- monitor the health of major components on large machines.
- Michelin MEMS – (Michelin Earthmover Management System) provides real-time data on tire air pressure and temperature.
- P&H Centurion – Shovel control system
- Banlaw Fuel Track – Electronic fuel monitoring system
- Novariant High Precision Global Positioning System (GPS) – Ground-based high precision GPS system.
According to Rajant, when first installed the Bingham Canyon mine mesh network initially accommodated the Dispatch, MineCare, VIMS, GPS, Aquila Drill Management and FuelTrack applications, but has enough bandwidth available to support other applications such as voice-over-VoIP telephones and extensive video-camera surveillance.
The initial installation consisted of 140 Rajant BreadCrumb XL and ME systems in an interconnected
network. Each of those BreadCrumb units has dual 802.11 radios. Since the initial installation, another 60 BreadCrumb radios have been added without disruption to the mine operations. The network is governed by Rajant’s InstaMesh technology which manages hundreds of connections from BreadCrumb units to other stationary or moving devices. (Rajant has since introduced a new BreadCrumb model, the LX, a multi-band, modular unit that can employ up to three radios.)
The system, according to Rajant, is an easily configured one-button operation, self healing and extendable without the need of an on-site IT specialist. The software used to administer the network, Rajant’s proprietary BCAdmin and BCCommander, is designed to be relatively easy for someone with a non-technical background to use. Examples of options offered by these two programs include:
- Topology map showing BreadCrumb and client device connections
- BreadCrumb/client device channel, frequency, MAC address, IP address, nickname assignment, signal and noise levels.
- BreadCrumb “time since last update” and battery levels
- Channel and link speed of connections
- Access control, security, and encryption settings
- Interconnectivity with other networks, both wired and wireless
- Port forwarding for BreadCrumb devices configured as gateways
- Access control, security and encryption settings
- Remote “zeroization” of encryption keys
- SSID settings
- DHCP server management
- Meshing and access point settings for each radio.
With Bingham Canyon’s mesh network allowing the mine to simultaneously run applications that track, monitor, and manage its operations, Rajant and Rio Tinto report that the mine was able to save $7 million in operational costs in the first 90 days of operation. A large part of this came from increased utilization of equipment. For example, with the network running maintenance and health monitoring applications from OEMs and aftermarket suppliers, the mine was able to reduce the maintenance cycle for many vehicles, and ultimately was able to have ten additional haul trucks in production at all times.