Mastering Land Mobile Radio (LMR) Backhaul Networks: Essential Lessons From Decades Of Experience 

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When boots are on the ground in a crisis, a split-second interruption in communication can be the difference between a first responder hearing “shoot” when the order was “Don’t shoot.” That is why an up-to-date and operationally robust Public Safety Radio System is essential to maintaining the high standards of reliability and quality of service that mission-critical operations demand. At Parsons, our decades of experience in engineering and maintaining these systems have put us in the driver’s seat in the evolution and challenges of radio system networks. Conversations with our customers on their networks tend to start out the same way. So, we wanted to distill our years of expertise into five key lessons to help anyone in the business maintain public safety communications systems and stay up and running.

What makes a Public Safety radio system networks unique? 

The first use of radio for public safety use came from the Detroit Police Department in 1921. It was an experiment by a pioneering commissioner – and it was a failure. It was not until 1928 that the basic system became functional and usable, setting in motion the eventual adoption of radio communications by every police department and emergency services organization in the nation. It also set in motion decades of innovation and change in radio technology. Radios became more portable, reliable, and affordable. Systems became more functional and stable. New capabilities emerged such as the ability to carry digital data. Nowadays, these radio networks resemble the large service provider networks of cellular carriers (e.g. AT&T, Verizon, T-Mobile, etc.) where reliability, quality of service and diverse functionality is critical. And still today, LMR remains the best way to deliver highly reliable, mission critical mobile communications – especially in difficult environments. Ultimately, it’s the mission of these networks and the requirements surrounding that mission that makes them unique and why land mobile radio remains the primary technology in use. Public safety requires uptime and performance requirements that far exceed those of ordinary mobile service providers – and most other network providers as well. As a result, their design, engineering, and support requirements also surpass their cellular service provider brethren. 

Even though radio communication networks have been around for a century, they continue to evolve and adapt with the changing needs of their users and technological advances. There are two major trends that are worth noting today in the industry. First, if you operate a radio network, you are aware of the convergence of network backhaul and internet protocol (IP) technologies over the past 20 years. The backhaul represents a key component of most LMR systems and is usually where your radio network and your IP network come together. This in turn means that cybersecurity challenges faced by most IP networks are also encountered by radio operators. So as cybersecurity threats continue to increase, radio operators need to further invest in adapting how they protect their network.  

A second trend worth noting is the shift towards Software Defined Networks (SDNs). A SDN leverages either software-based controllers or application programming interfaces (APIs) to communicate with hardware infrastructure and direct traffic through the network. As opposed to legacy networks—which use dedicated hardware for point-to-point connections— an SDN can create and control virtual networks via software components. SDNs present a new model for performance monitoring and management and represent a new challenge to identifying and troubleshooting issues in a mission critical network. 

5 Lessons Learned In Maintaining Public Safety Radio Networks 

We have been involved in design, engineering, implementing, and maintaining backhaul networks for decades and we have learned a lot along the way. The following are five key lessons Parsons has learned that you can apply to your own operational processes. 

  1. Weak spots occur in the transport between elements (sites or devices)

For starters, the physical elements of radios and radio towers are hardly ever the source of your pain points. That is because radios are comparable to tanks—they are nearly indestructible, and it is a rare occasion that one would ever break. Therefore, the weak spots are really found in the transport between elements (such as microwave or fiber). For example, errors can be introduced whenever microwaves are affected by the weather, the trees, or even buses in transit. These sorts of variables have a direct impact on wireless communication systems, though weather is often a primary culprit. With that in mind, it’s safe to say weaknesses in communication stem from the intangible transport of information, rather than the physical components you use to facilitate this process. 

Key Takeaway: Instead of purchasing new repeaters radio sets, look to upgrade or add redundancy to the transport equipment in your network. 

  1. You can never have too much redundancy 

A golden rule in building radio networks is that you can never have too many points of failures.. Multiple paths are a key tenet of highly available networks – and even though multiple paths are always designed into these networks, they are often under-engineered. Yes, two paths are technically ‘multi-path’, but the tradeoff here will often impact reliability and performance at some point. Most often we see operators avoiding the complexity associated with multiple paths concerned that it will trigger problems or be too difficult to and maintain. In practice, however, this is rarely the case and having more options within the routing infrastructure is a stabilizing factor. 

Key takeaway: Do not shy away from adding some complexity in search of more stability and reliability. 

  1. Quality of Service is everything 

It’s tough to overstate the importance of Quality of Service (QoS). To put it lightly, QoS is everything. A strong QoS is one that prioritizes voice traffic and allows public safety radio system backhaul networks to be multifunctional. With these features in tow, the Quality of Service for radio networks will no doubt exceed that of other network backhaul technology. A focus on quality can deliver highly consistent and reliable results, as well as reducing the chance of inaccuracies or disruptions that might crop up along your network. In addition, Quality of Service is essential in providing an excellent experience for each customer. 

Key takeaway: Make sure you benchmark, measure and work to improve your QoS. 

  1. Highly redundant, multipath networks often hide issues 

The idea that highly redundant networks often hide issues may seem contradictory to the notion that you can never have too much redundancy. And yet, this is the paradox that exists within most public safety radio networks, since both sentiments are inherently true. Because LMR networks work so well, when a transient failure occurs you might not even notice the issue right away. 

Surfacing problems is difficult because the systems are designed to fail-over and recover so fast via the high redundancy, and that when something goes wrong, those errors do not really surface to the radio system operator or owner. All those amazing benefits that redundancy has to offer will also trigger a substantial issue—in that when you do have problems resulting from the weather (etc.), they are typically not visible to the LMR operator. But that’s exactly where Quality of Service comes back into play. Engineering good backhaul networks with prioritized voice LMR voice traffic allows the abundant capacity to not only be multifunctional, but to carry out other services and systems across the same networks, as well. 

Key takeaway: Even though you may not be alerted to problems does not mean your network is not experiencing important errors that you cannot see 

  1. Tracking down backhaul issues that show themselves in the radio system network is notoriously difficult 

Tracking down backhaul issues that have surfaced in the LMR network is a major challenge. This difficulty stems from the fact that the tools monitoring these backhaul systems are not correlated to the LMR network in any way. And manually trying to link cause/effect between the system is almost impossible. Making this more difficult is the typical backhaul network manager software is not designed for a radio technician. As an example, the Vendor’s standard system monitoring software generates a “degraded sitelink” message (excessive jitter) at 3:05 am. Radio techs see the error and want to see where it happened. You would need backhaul monitoring that tracked the same data from the backhauls perspective and keep a timestamp to correlate the LMR with the Backhaul errors. 

Key takeaway: Look for tools that make it easier to correlate these issues on both sides of the network. Hint: only Parsons offers a solution to this problem. 

Wrapping up 

As you are thinking through all the requirements and responsibilities of building an LMR backhaul network, keep in mind that you need to build one with the same technology that is driving large scale carriers. This means creating a highly available network that has fast recovery, and that respects the seriousness (and urgency) of your data. More specifically, you will want to establish a network that prioritizes your public safety traffic, provides QoS, and is still adaptable to transport non-LMR systems.  

Let’s face it: most network management tools that monitor the backhaul of public safety systems are expensive and difficult to use. But what is worse, is that these operational difficulties result in more time to resolve issues than is acceptable for critical communication networks. A faster and more functional path forward is needed, to be sure. Fortunately, Parsons has designed an innovative platform that exceeds the capabilities of these other tools and helps you to operate much more efficiently. 

About The Author

Dallas Gamble is one of our Sr. Business Development Managers, helping North American SLED agencies effectively maintain and protect their complex municipal and radio system networks. Dallas’ passion within the organization is in staying ahead of technology pitfalls and ever-changing cyber-threats facing our nation’s critical infrastructure and jeopardizing our children, educators, public safety and first responder’s well-being.  

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