Multi-Tenant C-RAN With Spectrum Pooling: Downlink Optimization Under Privacy Constraints

Spectrum pooling allows multiple operators, or tenants, to share the same frequency bands. This work studies the optimization of spectrum pooling for the downlink of a multi-tenant Cloud Radio Access Network (C-RAN) system in the presence of inter-tenant privacy constraints. The spectrum available for downlink transmission is partitioned into private and shared subbands, and the participating operators cooperate to serve the user equipments (UEs) on the shared subband. The network of each operator consists of a cloud processor (CP) that is connected to proprietary radio units (RUs) by means of finite-capacity fronthaul links. In order to enable inter-operator cooperation, the CPs of the participating operators are also connected by finite-capacity backhaul links. Inter-operator cooperation may hence result in loss of privacy. Fronthaul and backhaul links are used to transfer quantized baseband signals. Standard quantization is considered first. Then, a novel approach based on the idea of correlating quantization noise signals across RUs of different operators is proposed to control the trade-off between distortion at UEs and inter-operator privacy. The problem of optimizing the bandwidth allocation, precoding, and fronthaul/backhaul compression strategies is tackled under constraints on backhaul and S.-H. Park was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (Ministry of Science, ICT&Future Planning) [2015R1C1A1A01051825]. The work of O. Simeone was partially supported by the U.S. NSF through grant 1525629. O. Simeone has also received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 725731). The work of S. Shamai has been supported by the Israel Science Foundation (ISF) and by the ERC Advanced Grant, No. 694630. S.-H. Park is with the Division of Electronic Engineering, Chonbuk National University, Jeonju 54896, Korea (email: [email protected]). O. Simeone is with the Department of Informatics, King’s College London, London, UK (email: [email protected]). S. Shamai (Shitz) is with the Department of Electrical Engineering, Technion, Haifa, 32000, Israel (email: [email protected]). October 18, 2017 DRAFT ar X iv :1 71 0. 06 09 4v 1 [ cs .I T ] 1 7 O ct 2 01 7