The following information may help with choosing the critical property and the classification of components into clusters. Each cluster has a corresponding story or failure scenario. For example: “when the power fails in this room, all these devices will stop functioning”. Creating such stories makes for a good check; if you cannot think of a plausible story, the cluster classification is probably incorrect.
Interference. The critical property is the frequency band, together with geographical proximity. For two wired links to be affected by the same radio source, that source must be transmitting on a near frequency, and be relatively close.
Jamming. Most jammers operate on a single frequency band. Because the use of a jammer is intentional, the motive of the person jamming is relevant. Most jammers have a limited range. Clusters can be organised based on “who may want to jam communication where, and for which motive?”
Congestion. Congestion is mostly temporary. When there is a high amount of activity in the neighbourhood, the mobile or private networks may become congested. Congestion may therefore affect multiple frequency bands simultaneously (GSM, UMTS and LTE, for example). Depending on the technology used, congestion may be local or affect the entire telecommunication service.
Signal weakening. This vulnerability is mostly limited to mobile devices. A common cause failure requires one person using two devices is at a spot with poor coverage (for example, using a mobile phone and a two-way radio), or that two users are at such a spot.
Break. The critical property is geographical proximity; cables sharing the same location can be damaged simultaneously by external influences. Cables below the ground often follow the same route, or share a common duct underneath roads or canals.
Congestion. As for wired links.
Cable ageing. The critical property can be whether the cable is used above the ground, below the ground or indoor. If the age of the cables is known, a subdivision based on age can be used.
Physical damage. For fixed equipment the critical property is geographical proximity. Mobile devices have their own cluster, with possibly subclusters for different types of users.
Power. For fixed equipment the critical property is geographical proximity. Mobile devices have their own cluster; subclusters can be created according to battery life.
Configuration. The critical property is who controls or can change the configuration settings: the IT department, an external service organisation, professional end users or common users. Computers are maintained by the IT department, but their users can often change settings (accidentally) as well. In this case, assign the device to the most vulnerably cluster.
Malfunction. Devices are often bought in batches. It is not impossible for multiple devices to fail (roughly) simultaneously. Age is a relevant property, but the kind of use and treatment are relevant as well. Devices that experience rough handling will have a higher probability of sudden malfunction than devices at a fixed location.
Often a single project meeting suffices, after which the core team completes the assessment of common cause failures.