Whether you are protecting your critical communications from natural disaster, human error or terrorism, deciding on the level of backup you need is a balancing act between your perceived risk and how much you can afford to spend.
How many levels of backup do you need? What industry or legislative regulations are in place? What options will give you the most resilience for your investment? Richard Winter, a Senior Systems Engineer at Tait, considers some of the ways your network design can eliminate single points of failure and increase the resilience of your network.
Resilience, redundancy and getting a good night’s sleep
The backhaul network which interconnects the sites and control centers is the big-ticket item on your comms resilience list. Protection measures such as multi-path routing, ring structures and duplicate bearers should be included, to guarantee high system availability. Investigate your choice of bearers too – each has its own cost/benefit ratio.
Multi-channel trunked radio sites provide inherent protection from channel failure; if a channel goes down, the remaining channels will automatically adjust to maintain normal trunked operation. Traffic handling capacity will be reduced, but radio users don’t need to take any special action to maintain communication, as the channel controller always selects a channel from those available. Your users will normally be unaware of the failure.
- Duplicated/ decentralized control
Duplicating your control center function can protect against the loss of your dispatch facility in the event of fire or evacuation. You could specify a fully-redundant back-up center, or you can spread control between two (or more) centers in different locations that are normally operational so any one center can take up the load from a disabled center when needed.
- COWs (Comms On Wheels)
Extreme weather events can indiscriminately put communication sites or their linking out of action. A COW (Communication on Wheels) trailer or truck with its own repeaters, antenna and linking capability can provide temporary communications in an affected area. Adding a small, rugged Private Broadband LTE system can offer high speed data.
- Offsite control
The IP-based console systems used with today’s communications networks mean that you can manage your dispatch operation remotely, away from the normal control centers – wherever a network connection is available.
- High availability
The degree of protection from server failure is a significant factor in your system design and affects the number and location of servers. Redundancy for servers in IP-based radio comms networks may involve basic main-standby arrangements, but multiple servers in a geographically-diverse configuration can further protect your network against failure or total loss of facilities. In this configuration, all servers share the day-to-day handling of radio traffic. If a server fails, or is isolated due to link loss, the remaining servers step in to provide continuity of communications.
- Alternative access
Alternative access for dispatchers is critical, when there is disruption at the control center, such as a forced evacuation due to a fire alarm or bomb alert. Radio-based access, via portables or control station mobiles, is a cost-effective and reliable way to maintain communications with workers in the field. Control station mobiles may have a handset and in some cases a reduced-feature console. Mobiles with extended remote control heads – and even dual remote control heads – can be installed in buildings to position the radio body and antenna in the least vulnerable place, while still providing a full mobile user interface inside an office or control center. You can also use the control stations for off-air monitoring.
- Power at sites
One of the biggest risks to your communications is also one of the simplest. Statistically, the most common cause of communications failure is power at radio sites. Backing up your power supplies with dual – even triple – redundancy can prevent communications outage, particularly where towers are at elevation, remote or inaccessible during winter.
Not all your solutions are technical ones. Because you are providing essential services, you are already bound by regulation and compliance. How you manage the communications aspects of your business is a vital part of your reliability picture. Developing and enforcing robust processes around your comms, assigning clear responsibilities and logical, well-understood procedures will reduce outage risk and support swift, decisive responses to events.
Of course it doesn’t matter how much you spend, and how advanced the technology, your communications network is only as good as the people who are using it. It is often tempting to save on staff training, to rely on training on the job, self-training, or internal courses. Whether they are dispatching, monitoring, maintaining or simply communicating, your people’s competence and efficiency contribute significantly to the reliability of your network and the return on your investment.
This article is taken from Connection Magazine, Edition 4. Connection is a collection of educational and thought-leading articles focusing on critical communications, wireless and radio technology.
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