Co-Tenant Interference Profiling

Problem

Controllers that share a substrate rarely collide on a parameter; they collide through the medium that couples the parameters they each own separately. One xApp owns transmit power, another owns resource-block allocation or handover offset. They never write the same field, so a static reading of their action spaces shows no overlap and the design review finds nothing. Radio physics couples them anyway: both move cell coverage, and the damage shows up only as degraded outcomes. PACIFISTA measures it — a 16% throughput loss between xApps with similar goals, and up to 30% performance degradation plus instability between xApps with opposing goals. Worse, the coupling is conditional rather than constant: two xApps may conflict under certain conditions and coexist under others, so a single review, or a single test run, cannot settle whether the pair is safe.

Solution

Stand up a sandbox that reproduces the substrate faithfully enough for outcomes to be comparable — an emulated radio environment, a plant digital twin, a physics simulation of the floor. Keep a registry of the incumbent controllers currently admitted to the fleet. When a candidate arrives, run three configurations for every incumbent and every declared operating condition: the candidate alone, the incumbent alone, and the two together. Collect end outcomes rather than actions — throughput, tail latency, handover failures, oscillation amplitude — and compare the joint run against each solo baseline with a statistical model, so that run-to-run noise is separated from real degradation. The result is an interference matrix over the fleet: one severity score per pair per condition, plus the conditions under which the pair is safe. The admission gate reads that matrix. A candidate with no measurable degradation joins. A candidate with mild degradation joins with its actuation scope narrowed, or with a mediator placed between it and the substrate for the parameters implicated. A candidate that drives an incumbent into instability is refused, and the refusal names the pair and the condition rather than a general objection. Because the matrix is a property of the fleet, admitting anyone invalidates it: re-profile when a controller is added, updated, or when the substrate itself changes.

When to use

• Several independently developed controllers actuate one shared physical or economic medium and are admitted to the fleet one at a time.
• Controllers write disjoint parameters, so a comparison of their action spaces cannot show a conflict that the medium nonetheless creates.
• The damage from a conflicting pair is emergent over sustained joint operation rather than visible in any single action.
• A sandbox exists that reproduces the substrate faithfully enough for outcome measurements to transfer to production.
• Actuation reaches many users at once, so discovering the conflict from production telemetry means the degradation has already been served.