Inter-Tenant Cooperative Reception for C-RAN Systems With Spectrum Pooling

Abstract

This work studies the uplink of a multi-tenant cloud radio access network (C-RAN) system with spectrum pooling. In the system, each operator has a cloud processor (CP) connected to a set of proprietary radio units (RUs) through finite-capacity fronthaul links. The uplink spectrum is divided into private and shared subbands, and all the user equipments (UEs) of the participating operators can simultaneously transmit signals on the shared subband. To mitigate inter-operator interference on the shared subband, the CPs of the participating operators can exchange compressed uplink baseband signals on finitecapacity backhaul links. This work tackles the problem of jointly optimizing bandwidth allocation, transmit power control and fronthaul compression strategies. In the optimization, we impose that the inter-operator privacy loss be limited by a given threshold value. An iterative algorithm is proposed to find a suboptimal solution based on the matrix fractional programming approach. Numerical results validate the advantages of the proposed optimized spectrum pooling scheme. Index Terms-C-RAN, multi-tenant, spectrum pooling, privacy constraint, fractional programming, multiplex-and-forward. I. INTRODUCTION Network slicing is a key technology for future wireless communication systems [1]. Two examples of network slicing are radio access network (RAN) sharing and spectrum pooling, in which network operators share infrastructure nodes or frequency spectrum in order to meet the growing demands for high data rates [2], [3]. Another promising network architecture is cloud RAN (C-RAN), which is being deployed for performance evaluation. In a C-RAN system, baseband signal processing on behalf of a set of distributed radio units (RUs), also known as distributed units (DUs) in 5G New Radio (NR) [4], is jointly carried out by a cloud processor (CP), known as central unit (CU) in 5G NR [4], that is connected to the RUs through fronthaul links [5]-[7]. Reference [8] studied the downlink of a multi-tenant C-RAN system with spectrum pooling, in which C-RAN downlink systems of two network operators cooperate to maximize the total throughput.

Clustering and Beamforming for User-Centric Cell-Free Massive MIMO With Backhaul Capacity Limitation

“…To that end, first, we consider the canonical form To put (38b) into the form of (37c), each term in (39) must be expressed with real variables. In particular, the quadratic term in (39) can be rewritten as…”

“…With this approach, we can forward received I/Q data and estimated channel via backhaul links, but we must also quantize the signals because insufficient capacity is sometimes available with high demand from connected UEs. For example, the performance of cloud radio access networks with limited backhaul links among cloud processors [39], [40], [41] has been investigated. In those works, limited backhaul links are modeled as quantization noise caused by low-bit analog-todigital converters.…”