Underground mining has changed dramatically during the past 20 years. Communication technology is used everywhere to manage air handling, provide supporting infrastructure for two-way radios, permit intranet and internet connectivity for workers, link remote stations to CAD and engineering systems on the surface, facilitate autonomous and remotely controlled mining operations, integrate SCADA control, dewatering, and much more. Communication networks are not only critical for operations, but provide the essential lifeline for health and safety.

These communication systems have evolved sporadically and erratically over the past two decades. A few operators have sophisticated and state of the art solutions, but most are struggling to maintain legacy elements that make them challenging to manage and maintain. In the majority of cases, they are highly disjointed and disorganized. These systems are old and obsolete with antiquated equipment and technology that is end of life and no longer supported. They are rarely designed in a robust manner, are misaligned to operations, lack spare parts, lack training, and adequate test equipment and jigs.

AFL Global

The main problem that we see repeatedly is that these communication networks are composed of multiple, disparate technologies. Sometimes as many as six or eight different optical fibre technologies are used at a single mine site. The communication networks are composed of a hodgepodge of technologies from a variety of vendors selected from the solution du jour or purchased from a favourite seller based purely upon relationship. There is no consistency in the design nor any systematic approach to the implementation. There is no harmonization within these networks.

How did we get in this mess in the first place? This is typically answered by stating that it is a result of the business organizational structure of the mine operations.  It is due to how each department has its own budget built based solely on each department’s isolated needs and requirements. These siloed operations are a huge quandary and a conflict to a harmonized and integrated budget process. The solution is not necessarily to reorganize the mine, but the way that budgets are created and spent. A second issue is to possess a shared mine communication architecture with applicable governance to guide future decisions, even disparate ones.

Therefore, we see risk everywhere when a cohesive budget process is not available and when the corporate communication network architecture is missing or not followed.

In stark contrast, we always hear how critical these networks are for production to achieve cost effective yields for the ores mined.

When we are asked to look at the communication networks used for mine operations and make recommendations for improvements, we can see some easy fixes to these problems.  We continue to see the same basic mistake reoccur in communication network strategy.  Meaning, there is no comprehensive and cohesive strategy – nothing, none at all.  As a consultant, we can easily solve this problem, just make a cohesive technical plan and get it implemented.

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However, it is normal to face great political resistance to this approach.  Why?  Well, back to the isolated or siloed business operations within the mining industry. So, maybe business process optimization (BPO) is necessary for some mining companies.  No two operators are the same because of the distinct structures of each business and their specific needs that must be appropriately considered.  There is no “one size fits all” solution.  However, when basic components of best practices for IT / OT are absent, then adding them into the mix is the easy part towards fixing the problem.

What options are available today for underground mine communications networks?  We have three main technologies to consider and they all have merit. These technologies are

  1. IP/MPLS,
  2. Carrier Ethernet,
  3. Optical Transport Network.

Other solutions like SONET are still commonly used, but are rapidly nearing end of life since they cannot scale well to meet increasing big data demands.

As stated, they all have merit. The manner in which the Mine is organized plays a big part in the technology selection process.  Most agree that SONET is beyond its useful life so the debate turns to IP/MPLS versus Carrier Ethernet. The Optical Transport Network or OTN has not gained the level of marketshare to see it as a viable alternative over the next decade so just two options remain.

IP/MPLS

IP/MPLS (internet protocol / multi-protocol label switching) is a leading technology with great ability to scale and impressive data handling capacity. There are many quality vendors and several equally impressive bolt-on standards to help mitigate some integration challenges for the OT side of the house. The IT folks can embrace it fully too. Nevertheless, depending upon the current and future approaches to smarter mining operations, it may not be the best choice for OT. A few issues make IP/MPLS difficult for OT. For example, it is a layer 3 technology so it has the overheads and delays of TCP/IP. It can use different paths in the forward direction versus the reverse direction meaning that the latency in both directions can be different.  For OT applications with sensitivity to clocking and time delays, we add technologies like the ITU’s SyncE (Synchronous Ethernet), IETF’s NTP (network time protocol), or the ever popular IEEE 1588 version 2.  However, even with these clocking solutions, IP/MPLS is still non-deterministic. Some OT application and Mine SCADA technologies prefer a deterministic network solution. Numerous protocols need to be set and maintained within the IP/MPLS networks, so it can be complex to operate for smaller operations without the qualified staff on site 24/7.

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Carrier Ethernet

Carrier Ethernet has advantages over IP/MPLS and is often preferred by the OT side of the house since it is the natural outgrowth of the older SONET standard that many operators have used in the past, but it is still a frame based technology which is different than the packets used in IP/MPLS and the cells used in SONET.  Carrier Ethernet is generally considered lower cost to implement compared to IP/MPLS. While IP/MPLS can scale to thousands of sub networks, Carrier Ethernet can scale to hundreds of sub networks, still very respectable and not a barrier for Mines (compared to telecom carriers that service more nodes). Carrier Ethernet is the preferred technology by telecom carriers to connect data centers and other mission critical network nodes. Carrier Ethernet offers lower latency compared to IP/MPLS. It is a Layer 2 solution. Carrier Ethernet is an all Ethernet structure so it can connect end to end with Ethernet, it is better than IP/MPLS in this regard which needs to convert between IP/MPLS and Ethernet at the network edges.

What other types of networks might we see in a Mine that we should be considered for retirement? Legacy optical networks include:

  1. Optical Transport Networks (OTN)
  2. Wave Division Multiplexing (WDM)
  3. Gigabit Ethernet (GigE)

Optical Transport Network

OTN (optical transport network) is an ITU standard for wrapping a variety of signal formats like SONET, Gigabit Ethernet, and Fiber Channel.  It is used to wrap these different signalling formats into a common Layer 1 optical foundation to improve the functionality of transport, multiplexing, switching, management, supervision and survivability of optical channels carrying IT / OT signals. It is used with WDM (wave division multiplexing) and applies each signal to its own wavelength. Rather than using a form of encapsulation into a common carrier format like Carrier Ethernet or IP/MPLS, OTN permits the discrete signal formats to be individually mapped to the OTN structure and are carried in parallel.

While OTN is cost effective, it is limited in flexibility and usability for Mining needs. OTN varies its latency depending upon the source signal being wrapped and therefore different signal types will flow over the same optical pathway in different time duration.

Panda Mine – South Africa

Wave Division Multiplexing

Wave Division Multiplexing (WDM) is a means to carry multiple wavelengths or frequencies of light simultaneously over a single strand of optical fibre. WDM is able to provision bidirectional communications over the same strand of glass. The first systems used just two wavelengths of light but it is possible to multiplex up to 160 frequencies today, although lower number of frequencies is more common today such as 16 or 24 wavelengths. Two flavours of WDM are used, Course Wave Division Multiplexing (CWDM) and Dense Wave Division Multiplexing (DWDM). Other variants of these two types are seen, but these two are the most popular. In the Mining world, we normally just use DWDM. This approach uses the 1550 manometer (nm) band. Therefore, the glass used must have this wavelength window available. Normally, glass is purchased with three windows for the greatest flexibility, 850 nm, 1310 nm, and 1550 nm. Reconfigurable Optical Add-Drop Multiplexer (ROADM) is the main termination device used at fibre nodes to deliver or add traffic to the network. ROADM devices operate on WDM networks and can selectively manage individual wavelengths. When the optical fibre network is configured as a mesh architecture, then Optical Cross Connects (OXC) matrices are used to map the fibres to each other. For long distance transports of signals, IP/MPLS and Carrier Ethernet ride over these DWDM networks and can use ROADM and OXC at termination points or network nodes.

Gigabit Ethernet

Gigabit Ethernet is a common access connection solution in baseband formats over copper wire. However, it can be delivered in five physical layer standards for Gigabit Ethernet using optical fibre (1000BASE-X), using copper on twisted pair cable (1000BASE-T), or shielded balanced copper cable (1000BASE-CX). Sometimes it is used in intra-mine links as point-to-point connections to connect levels. It is not scalable and should be replaced when data rate demand a better solution.

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Conclusion

The world of optical networks within a mining environment does not need to be overly complex. Once the traffic types are known, and properly quantified, then the best solution can be evaluated and identified. Deep knowledge of the applications and their expected traffic flows, regardless if they are IT or OT, will make the task of selecting a technology solution much easier. The key strategies are:

  • Simplify
  • Consolidate
  • Integrate

So, begin with the needs first, then look to the architecture, and finally consider the technology to make it all work. Too often, we see clients start with the technology first and this is wrong. A perfect network is one that is invisible to the Mine applications. Business is run on the applications, and then networks are built to serve these applications. Do not get caught in the techolust arguments that we see far too often. Engineers love their technology, but it is the business of running a profitable mine that is paramount, not the toys for the boys. Without doubt, technology is the foundation upon which the business operates. Therefore, while it is important, it should never dictate how the business runs; the best solutions underpin the business imperatives and the workflows.


About the Author

Michael Martin has more than 35 years of experience in broadband networks, optical fibre, wireless and digital communications technologies. He is a Senior Executive Consultant with IBM Canada’s GTS Network Services Group. Over the past 11 years with IBM, he has served in the GBS Global Center of Competency for Energy and Utilities and the GTS Global Center of Excellence for Energy and Utilities. He was previously a founding partner and President of MICAN Communications and before that was President of Comlink Systems Limited and Ensat Broadcast Services, Inc., both divisions of Cygnal Technologies Corporation (CYN:TSX). He holds three Masters level degrees, in business (MBA), communication (MA), and education (MEd). As well, he has diplomas and certifications in business, computer programming, internetworking, project management, media, photography, and communication technology.