Fried Parameter-Based Cost Function for Dynamic Metropolitan Free-Space Optics Circuit Routing

Free-Space Quantum Networks and Optimized Fiber-Reinforcement

It is proved that any optimal backbone configuration must correspond to a capacity-maximizing Voronoi tessellation of the network region, and this can be efficiently approximated by a centroidal Voronoi tessellation via Lloyd's algorithm, with backbone nodes connected according to a Delaunay triangulation.

Efficient routing and spectrum allocation in arbitrary flex-grid entanglement networks

As practical quantum networks approach large-scale deployment, the need for efficient user-to-user frequency allocation is increasing, yet current approaches only provide partial solutions to the routing and spectrum allocation problem for an arbitrary quantum network. We address this challenge for repeater-less flex-grid quantum networks based on hyperentangled photons using an efficient three-stage pipeline combining leading tools in classical networking with recent advances in numerical optimization. First, double instantiations of Yen's algorithm obtain low-loss route candidates between each pair of users and the entanglement sources. Second, the advanced process optimizer (APOPT) obtains frequency channel allocations that maximize distribution rates under fidelity constraints. Finally, the constraint programming solver using satisfiability methods (CP-SAT) assigns specific frequency bins to each link, ensuring that there is no contention between frequencies from different sources. We numerically demonstrate this approach on a representative ring network and a Manhattan incumbent local exchange carrier topology, realizing significant improvements over prior genetic algorithm approaches in speed, accuracy, and scalability. Overall, this pipeline provides an efficient heuristic workflow for optimizing broadband entanglement distribution, applicable to arbitrarily connected quantum networks integrated within the existing lightwave infrastructure.

Coverage and Rate Analysis of Cell-Free RSU-Enabled Vehicular Networks With Poisson Line Cox Processes

Providing seamless connectivity in vehicular networks is fundamentally constrained by the rigid service boundaries imposed by conventional roadside unit (RSU) architectures. To overcome these limitations, this letter proposes a cell-free RSU architecture and establishes a tractable stochastic geometry framework for its performance analysis. By modeling both road topology and transceiver locations as a Poisson line Cox process (PLCP), the spatial randomness inherent in vehicular networks is accurately characterized. The coherent desired signal is approximated by a Gamma distribution through moment matching, while the Laplace transform of the road-constrained aggregate interference is derived in exact form. Building on this, closed-form expressions for the coverage probability are obtained using complete Bell polynomials, along with a single-integral representation of the ergodic rate. Numerical results validate the analytical framework and demonstrate that the proposed architecture clearly improves array gain exploitation and resilience to traffic-induced congestion over conventional single-RSU and fixed-size clustering deployments.

Vertical FSO Link Modeling and Turbulence-Aware Resource Management for Enhanced Non-Terrestrial Connectivity

Geometric Topology-Based Association Strategy in Large-Scale RIS-Assisted THz Networks

FlowForm: Scalable Passive Metasurface Network for mmWave Coverage Expansion

Millimeter wave (mmWave) networks offer multi-gigabit data rates but suffer from severe path loss and blockage, resulting in spotty coverage. Emerging reconfigurable intelligent surfaces (RIS) can mitigate these challenges, but their reliance on active control channels, power sources, and complex runtime coordination imposes significant hardware and deployment overhead. This paper introduces FlowForm, a system that expands mmWave coverage using networks of passive metasurfaces that require no power, control, or runtime coordination. FlowForm's key innovation is a hierarchical flow topology that organizes passive metasurfaces into major flows (directional relay chains using near-field focusing) and minor flows (wide-area fan beams), enabling multi-hop passive routing and over-the-air combination of analog signals. We develop a theoretical framework establishing the optimality of this topology and a hierarchical optimization algorithm that jointly determines metasurface placement and beam configurations. FlowForm operates transparently with standard mmWave network protocols, managing channel dynamics and multi-user interference through diversity-aware design rather than runtime reconfiguration. Our experimental evaluation across five indoor environments demonstrates up to 94% average rate improvement and 114% coverage expansion using low-cost 3D-printed metasurfaces ($2 per unit), achieving performance comparable to active RIS at orders of magnitude lower cost.