When deploying an outdoor wireless network, a choice is usually made between building a short-range mesh or a long-range PtMP/PtP system. A short-range mesh is normally used for downtowns, “hot zones” and campuses, and provides all the benefits normally attributed to meshing, such as fault tolerance due to re-routing and fast, easy installation with little need for link engineering due to the large amount of peers available. But the problems include:
- shorter links
- the need for more wired or wireless backhaul
- unpredictable service due to the large interference domain
To provide longer range communications, a PtMP or PtP system can be used. This is normally used for applications such as fixed wireless access to homes or businesses, and smart grid backhaul, especially in medium density to rural areas. But problems with this model include:
- a lack of redundancy due to each client normally seeing only a single base station
- many base stations are required due to single hop
- the need to engineer each link
- incomplete coverage (each client must have a direct path to a base station, so some installations may be completely obstructed, and the network must be built very densely to minimize this)
To address some of these issues with each type of system, an architecture started to emerge a few years ago which combined PtMP backhaul along with omni-directional mesh. However, not only does this require two different solutions and sets of equipment, but the many of the issues are inherited from each type of system. For instance, while a subscriber connecting to the short-range mesh may benefit from the many mesh nodes available to choose from, there is still a need to engineer the backhaul links and there are still issues around interference with the short-range mesh. The PtMP system would still need to be built very densely to provide sufficient coverage and in order to compensate for the single hop links, and there still may be coverage holes due to obstructions. Also, the PtMP system lacks redundancy. And although it may be possible to use multiple meshes to heal around back-haul outages, this requires complex dynamic routing to be run between the backhaul network and the short-range mesh, and requires multiple adjacent short-range meshes which may not be present in situations where the meshes are islands within a larger sparse network.
One of the reasons that we chose to implement dynamic antenna pointing was to address both of these network architecture issues by providing a single system that can do both long-range backhaul and short-range meshing. In fact, while our first internal testbed ran over 7 hops that ranged from 10 yards to 300 yards, our first customer deployment connected mountain tops across 20 mile links. Over the shorter links the dynamically switched antennas have the isolation needed to avoid interference and to provide spectral reuse, while over longer links the antennas provide the gain needed to close the links at a decent modulation. These very different deployments use the same hardware, same protocol and exactly the same configuration – the only difference is the deployment locations.
Below are snapshots of two live deployments, one mostly PtMP (with one SkyExtender relay) and one dense mesh. The PtMP system has a mixture of links, from short to several miles, while the dense mesh has links of mostly under 100 yards. These systems are running equivalent hardware (although DualBands are used in the dense mesh), the same software, with the same basic configuration.
In some rural areas there is even a hybrid model that some customers use with the SkyPilot equipment where pockets of dense subscribers, connected to each other using short links, are interconnected using long distance links. For example, there are areas of rural Germany where a single SkyGateway connects over long links to SkyExtenders in different villages, which then mesh over shorter links with other SkyExtenders and SkyConnectors within the villages.
