AI summaryⓘ
The authors study how multiple mobile network operators (MNOs) can share wireless spectrum more efficiently using big antenna arrays. Instead of dividing the frequency bands into exclusive blocks that often go unused, operators can use their antennas to both serve their users and reduce interference to others, allowing simultaneous reuse of the same spectrum. They test different levels of cooperation between operators, from fully separate use to some sharing of scheduling information. Their results show that even a little coordination between operators can more than double the average user data rate compared to strict splitting or no cooperation. This means simple information sharing between operators can unlock much better use of the limited spectrum without needing complex joint processing.
Spectrum sharingMobile network operator (MNO)Spatial degrees of freedomNullformingMulti-user MIMOInterference suppressionOrthogonal partitioningSchedulingRay tracingCarrier frequency
Authors
Alberto Ceresoli, Marco Mezzavilla, Ilario Filippini, Antonio Capone
Abstract
Spectrum exclusively licensed to each mobile network operator (MNO) is scarce, and assigning it in fixed, frequency-orthogonal blocks leaves much of it idle under heterogeneous, time-varying traffic. Large antenna arrays offer an alternative: an operator can spend part of its spatial degrees of freedom (DoF) serving its own users and part suppressing interference toward others' users (nullforming), letting competing networks reuse the same band. This raises two questions: does trading DoF for interference suppression beat orthogonal partitioning, and how much coordination is needed to realize the gain? We cast inter-operator sharing as a continuum of cooperation "shades" of a single null-forming MU-MIMO precoding and interference-constrained scheduling primitive, spanning orthogonal partitioning, non-cooperative reuse, cooperative cross-operator protection, and a scheduling-aware bound exploiting foreign scheduling decisions. Evaluated on a ray-traced digital twin of a real multi-operator deployment with 27 base stations sharing a 7 GHz carrier, the cooperative shades deliver more than a 2.5$\times$ median per-user rate gain over both non-cooperative reuse and orthogonal splitting. Crucially, most of this gain requires only minimal inter-operator information exchange, indicating that a modest, standardizable metadata exchange, rather than tight joint processing, unlocks most of the value of shared-spectrum operation.