Decentralized Multisubsystem Weighted Interference Cancellation With Coded Caching

To both eliminate interference from unrequested subfiles and improve sum Degree-of-Freedom (DoF) in multirelay Internet of Vehicles (IoV) systems, a new decentralized multisubsystem weighted interference cancellation (DMS-WIC) scheme with coded caching is proposed. It divides the transmission into two stages with optimized parameters to minimize link load. It also improves the sum DoF by jointly combining the weighted interference cancellation, orthogonal unicast, and decentralized coded multicast together. Given the number of interference-free subfiles larger than that of users, traditional interference cancellation wastes cache capacities of both users and relays by ignoring partial cache capacities and, thus, it fails to achieve a balance between the number of both users and interference cancellation subfiles. The DMS-WIC achieves additional DoF by adopting orthogonal unicast and subsequently dividing cache of both users and relays compared with those of traditional interference cancellation. In other cases, the weighted requested subfiles are transmitted by combining physical layer file division and network layer coding delivery together to achieve interference alignment and cancellation gains. The DMS-WIC adaptively adjusts files and subsystem partition parameters by perceiving systematical parameters. Besides, a multirelay cooperative coded caching is introduced to further reduce transmission and complexity. Given the number of relays larger than that of users, the relays deliver coded subfiles with different user sets. Otherwise, a relay skips the fix of the user number units, until all user sets are taken after the completion of a transmission. Simulation results show that the proposed DMS-WIC with coded caching achieves more than 10.6% sum DoF gain compared with that of traditional interference cancellation.