Wireless point-to-point or point-to-multipoint networks supplement campuswide Ethernets, bridging networks and avoiding a backhoe problem, but otherwise they act much like a line-of-sight wire or a high-tech tin-can-and-string network.
Although point-based wireless networks that use unlicensed radio bands in the 2.4GHz and 5GHz range are often inexpensive and uncomplicated to install, they quickly max out their potential when line-of-sight obstacles stand in the way or the number of points exceeds a relatively low limit.
The successor and perhaps ongoing complement to point-to-point is a mesh network. In many ways, a mesh network resembles an idealized version of top-level Internet backbone routing in which physical location is less important than capacity and network topology. Only one or a few nodes need to be connected to a wired backbone or some sort of network uplink, and each packet bound for the same destination might proceed along a different sequence of nodes.
In point-to-point networks, each link requires a dedicated connection; in point-to-multipoint set-ups, the multipoint transceiver winds up being the bandwidth bottleneck and the point of worst failure. A mesh can distribute bandwidth and risk, while reducing the cost of deployment and expansion.
Depending on the implementation, each mesh node has a degree of autonomy or algorithmic intelligence that guides how it optimizes paths from instant to instant, whether in mobile networks or conventional networks in which the load shifts dynamically.
In the ideal mesh network, nodes provide automatic failover, locking out dead or nonresponsive peers, and routing is revised without any manual reconfiguration when new nodes are added.
Mesh networks divide almost neatly into two types: fixed wireless installations that connect multiple locations and mobile, peer-to-peer, ad-hoc networks that have variable availability and a potentially everchanging set of members. One also could deploy mobile or temporary networks that have the same properties as a fixed network.
Fixed mesh networks are generally built with the expectation that many nodes have no direct backhaul, network, or Internet access. In fact, if each location had some kind of enterprise or Internet access, distributing service by wireless would be almost unnecessary.
In a fixed installation, locations for nodes are chosen with an eye for providing the right overall level of bandwidth with the fewest points. Fixed mesh networks also can effectively offer non-line-of-sight service by ringing an obstacle -- a tall building, a hill, a cluster of trees, an area of known interference -- with enough nodes to bypass it. These fixed networks are typically directional enough over each link to avoid major security risks.
In contrast, peer-to-peer mobile mesh networks -- which are a long way from actual deployment -- rely on individual devices connecting to each other through devices within radio range. Scalability can be an issue because each device has to manage known optimal paths, which can change from millisecond to millisecond. When an uplink of some kind is added via cell, satellite, or wire, the network becomes dynamically aware and can handle queued interactions.
Security is of paramount concern in mobile meshes, although the technology's use in military battlefield projects provides some security through obscurity. Because of the ad hoc nature of mobile mesh, most of its use would be in the wild, outside of enterprise control.