MICAN does cellular, but normally private cellular and not public cellular. Private cellular is normally used for some form of industrial automation projects. It is not meant to be a replacement for the consumer cellular networks from the carriers, but is meant for automation of factories, autonomous mining, and a variety of closed network applications.
As an example of private cellular is the advent of the use of drones as a means to create ‘pop-up’ cell sites for emergency restoration, special event coverage, or to provide short-term coverage for a dynamic situation such as at an open pit mine site.
Drones are finding many new and interesting applications in a wide variety of commercial and industrial fields. It all began to a greater extent with aerial photography, mainly for the real estate industry used to capture beautiful images, both outdoors and indoors of deluxe homes. Shortly afterwards, drone applications evolved in many different directions simultaneously. A few modern examples of high value drone applications of note include:
- agriculture with LiDAR imaging of the crops to determine plant health,
- aerial thermal imagery searches for leaks, cracks, and faults on utility high power transmission lines,
- and, ultra high-resolution mapping and survey work of the nap of the earth terrain for mine sites, again using LiDAR and high resolution imagery.
Now, the telecommunication industry is looking at using drones to augment the terrestrial cellular based networks for special mission critical circumstances.
When major storms strike and damage telecom infrastructure, people are without communications and critical lifeline connections to get rescued, notify love ones of their location, and seek help to restore facilities. It takes time to restore damaged infrastructure and the first issue is access to the damaged cell sites. After a major storm event, road access is often greatly impaired, sometimes for days and weeks after the weather has stabilized. Replacement towers and other key elements of the cell site may have long lead times resulting in delays to restore the services. As well, repair crews are spread very thin with overwhelming workloads and simply cannot get to every site and every problem in a timely manner.
The solution is to deploy a drone. These drones will have a 4G cellular repeater mounted on the aircraft and fly it in a geostationary position high over top of the damaged infrastructure. It is effectively replacing the lost tower site. This sort of solution is a rapid deployment approach and can return services weeks in advance of the conventional restoration strategies.
The biggest problem facing this strategy is flight time. With a payload of perhaps 5 kg (11 lb), the flight endurance of the better more advanced electrically powered drones is around 30 minutes. To overcome this limitation, the drone is tethered to a ground trailer that has a generator in it as a temporary power source – if needed. Solar panels are used too along with a small bank of batteries. Flight powering systems, command and control of the drone, and 4G voice and data signals travel up these tether optical fibre cables to facilitate the service restoration. An amplifier and antenna built into the drone radiates the 4G cellular signal back towards the users on the ground.
Multiple drones can operate as an array, in concert with each other, to expand coverage to a greater geographical footprint. The idea is that in an emergency, a drone could hover over a disaster area to provide instant replacement 4G mobile network coverage with a 50km (31 mile) radius. So, a swarm of drones functioning as one cluster can cover vast customer areas. Services can be restored and augmented swiftly and straightforwardly. Inter-drone communication is possible with line of sight between these airborne drones.
A cellular feed to the drone ground station can arrive to/from the site via cellular relay from nearby operational towers or from satellites. The terrestrial option is preferred due to lower latency, but that may not always be possible if adjacent towers are out of service too.
For many years, we have used something called a ‘COW’ or a ‘cell on wheels’ to drive in to a troubled site and mount a pop-up mast tower to provide temporary emergency restoration services. These COWs are also used to augment services when large crowds gather at social events, car races, festivals, parades, and other gatherings. Now we have a new form of COW, this time a ‘cell on wings’.
The tethered drone can remain operational 24 hours per day for several weeks. The tethered drone can maintain its station-keeping at an optimal attitude of 168 metres (550 feet) above grade.
Beyond the telecom industry, First Responders are looking to drones to provide similar critical information quickly, so they can determine the safest and most efficient approach to solving a problem, such as putting out a fire.
In the case of a major high-rise building fire, drones can operate autonomously and in concert with each other. Belgian start-up firm Unmanned Life has developed software to send out multiple autonomous drones at the same time to gather information during a crisis, such as when a building is on fire.
One drone hovers in the air providing 4G coverage, while another flies around the building providing live video. A third equipped with heat sensors creates a heat map of the building, while a fourth uses sonar to map structural damage.
Swarms of co-operating drones, each with different tasks, help address the flight-time issue because single-function drones can be lighter.
And they can be lighter still if many of their computational and sensing functions – navigation for example – are undertaken by computers on the ground “talking” to the drones wirelessly.
The lighter the drone, the more it can carry.
When large crowds gather, cellular networks fail when the user demand dramatically outstrips the normalized coverage for the area. It is impossible to provide adequate services. For events like public celebrations, parades, protest marches, large sporting events, and major cultural festivals, literally a million people can turn out when normal coverage capacity is for tens of thousands.
With the prominence of the public using video streaming and taking pictures, cell towers get overwhelmed very quickly with high demands for data flows. Augmentation of the normal cell services is essential for these aberration events.
After the City of Seattle asked citizens around CenturyLink Field to limit their social media use in the Stadium District during the Seahawks opening game festivities, people weren’t too thrilled. “This is a joke, right?” one user commented. “Such a high tech city, can’t even use my smartphone at the stadium,” someone noted. “So ironic at the CenturyLink Field!”.
The City was concerned that too many people streaming video and uploading photos from their smartphones would clog cell networks and possibly prevent those in need from reaching emergency services. This wasn’t the first time the City issued a warning — during the Seahawks Super Bowl parade, the Seattle Emergency Operations Center sent an alert that asked people to wean off cell phone use to keep 911 networks open. Then at the Torchlight Parade, Seattle Police asked citizens to text friends and family instead of calling for similar reasons.
Drones have a new role to play in augmenting cellular services. When people depend upon cellular networks for emergency services, they cannot tolerate downtime. But, service outages due to storms, disasters, and major events are inevitable. So, having a fleet of low cost tethered drones available to augment cellular services makes immense sense.