Communications

Current threats to critical communications

Ken Rehbehn, principal analyst at CritComm Insights and representative of TCCA (The Critical Communications Association) investigates the different threats to the physical and digital aspects of critical communications.

Current threats to critical communications

Robust and reliable wireless critical communications networks are essential for a healthy and safe society. As vital underpinnings of a community, these networks must be protected from a wide range of threats that menace public safety operations. Peril comes from challenges to physical infrastructure, digital assets, and radio transmissions. But the good news is that multi-layered resilience can mitigate these current threats.

Physical infrastructure challenges

Critical communications wireless transmissions require physical tower sites supported by power and links to the network core. Because these physical assets must be distributed across the coverage region, the sites may be vulnerable to damage from natural or criminal events.     

Traditional government-operated transmission sites are hardened, which means they are designed to meet stringent requirements for physical security, power resilience, and backhaul redundancy. In this model, site access is protected with multiple layers of physical barriers and intrusion monitoring.     

Hardening also includes solutions for long-term power redundancy, including a combination of battery capacity for rapid power failover and a local generator set fuelled with multiple days of fuel. Plans for fuel resupply must consider the possibility of a transportation grid collapse following a wide-area natural disaster.

Ultimately, it may be necessary to airlift supplemental fuel.     

The last dimension of hardening involves the backhaul connectivity that links a transmission site to other sites and the network core. Fibre connectivity must be carefully designed to ensure true route diversity that ensures multiple independent paths.

The type of fibre or microwave route must also be considered. Fibre mounted to poles is at risk of sabotage, wind damage, or fire damage. Microwaves may be subject to wind damage or the loss of relay points.     

In contrast to government networks, the approach to hardening infrastructure deployed by mobile network operators is sensitive to cost and, consequently, less demanding. Cellular service economics relies upon high capacity in the cell sector, resulting in lower transmission power and extensive frequency reuse. These characteristics mean the cell system base station grid is far denser than a government Professional Mobile Radio (PMR) network.     
With the need to host many more sites, the mobile network operator has a reduced expectation for site hardening. Site access may be prevented by something as simple as a lock on a cabinet door. Incidents of attacks on 5G antenna sites by citizens fearful of radiation included the burning of 5G transmission antennas in the UK. Likewise, power resilience on cell sites is typically designed for hours of backup instead of days. A single strand of fibre may be all that is available for a link to the core network.     
Nations that plan to move push-to-talk group voice communications from PMR networks to a mobile network must establish plans for both transient and long-term failures of the cell network.

Following a massive natural disaster, recovery of the mobile network will be an extended process compared to recovery for a PMR network. Deployable cell sites help speed the process, but those deployable sites are subject to the same low power and poor spectrum propagation as standard fixed cell sites. The deployable cell site coverage can be very spotty.

The soft digital underbelly

Modern critical communications are marvels of software innovation. But that achievement brings complexity, expanding the threat vectors for digital attack or human failings.     

Cyber attacks on communications infrastructure can capture sensitive information or disrupt traffic. The good news is that PMR and mobile networks are designed with extensive protection against cyber attacks. Unlike typical enterprise networks subject to ransomware attacks, core communications network elements are based on UNIX and are isolated from general internet traffic by security gateways.     

Unfortunately, the complexity of cellular networks has resulted in a pattern of incidents triggered by human error. Errors in IP route reachability with the BGP protocol crippled a top-tier Canadian mobile network in 2021. The AT&T mobile cellular network supporting FirstNet failed due to an error while expanding the network in 2024.     
Attacks on the digital infrastructure also include the disruption of GPS/GNSS time signals. Accurate time signals are required for synchronising cellular handsets and the network. Because these time signals arrive from the satellite constellations at very low power, a local jamming source can easily overwhelm the space-based signal. Coping with failure

From an operational perspective, we must assume that critical communications will fail. The failure may be trivial and local, such as a fibre cut, or complex and national, as with a mobile core network configuration error. Though not frequent, these failures occur often enough to make resilience planning an essential element of any critical communications design.     

The acronym PACE is a valuable framework for addressing resilience: primary, alternate, contingency, and emergency. Primary is the standard day-to-day communications channel. If the primary channel fails, an independent alternate link is required.

A backstop contingency mechanism must be identified in the unlikely event that both the primary and alternate fail. Finally, an emergency approach must be identified in case none of the other routes are available, and an urgent message must be relayed.     

Providing these multiple layers of resilience requires planning and investment. Regrettably, many critical communications deployments fail to support a complete PACE plan due to cost or lack of vision.     

From an operational perspective, we must assume that critical communications will fail. The failure may be trivial and local, such as a fibre cut, or complex and national, as with a mobile core network configuration error. Though not frequent, these failures occur often enough to make resilience planning an essential element of any critical communications design.

Enter the vehicle as a node resilience concept 

One of the most promising approaches to multi-layer resilience emerged in Australia following the catastrophic 2019 bushfires in New South Wales. In response, the New South Wales Fire and Rescue Service designed a vehicle node that combines P25 PMR connectivity, an LTE alternative, and a GEO satellite contingency. This Vehicle-as-a-Node (VaaN) solution is being deployed across their fleet.     

In the New South Wales approach, a fire appliance communicates with the control room over P25 voice communication when within range of a P25 tower. If the tower is out of service or beyond range, the vehicle’s P25 radio switches to a P25 over IP using an ethernet link. A vehicle router forwards the IP traffic to a cloud-based gateway.

With no LTE signal, the vehicle router forwards the IP traffic over a low-speed satellite connection.     

Central Pierce Fire and Rescue in Washington State, USA, is implementing a reduced approach to VaaN. In this approach, a primary communications channel is LTE-based push-to-talk over cellular (PTToC) combined with an LEO-based satellite alternative.     
The primary benefit of the VaaN approach is that each individual network option can be less than perfect. The combination of alternatives boosts the resilience to levels far higher than can be achieved with a single super-hardened network. 

An additional benefit is that the VaaN concept can be further extended with ad-hoc mesh network connectivity to link teams that travel on foot from the vehicle in isolated regions. The resulting communications deliver high-quality, resilient communications supporting situational awareness, command, and control. Benefit from the wisdom of the crowd TCCA’s Critical Communications World 2024 brings together the top experts on critical communications from around the globe.

Ministerial officials and industry innovators will gather to discuss the latest approaches for resilient, high-performance critical communications. The conference and exhibition provide a valuable opportunity for local and national officials to hone the expertise needed to meet the critical communications mission.

Critical Communications World takes place from 14-16 May 2024 in Dubai. Moving forward with mission critical services certification The Global Certification Forum (GCF) is working together with TCCA  to develop an industry certification program for mission critical products and solutions where conformance to 3GPP standards will be checked and verified and thus ensure interoperability between different solution providers.     
The work on establishing this certification program will progress at a dedicated workshop on May 17, following Critical Communications World.

This workshop, the third in the series, will aim to gather input to the future development of the MCX certification programme, and will provide an opportunity to hear from local stakeholders to understand regional requirements and ensure alignment with industry. 

The workshop is open to all GCF and TCCA members, and to non-members subject to approval.

CritComm Insights is a member of TCCA.