Coordinated Jamming: A Privacy Preserving Method for C-RAN with Untrusted Radios

In this work, we study the uplink (UL) of a cloud radio access network (C-RAN), under the consideration of information privacy. In particular, we consider a system where the UL communication takes place with the presence of idle users (IUs), which act as the undesired information receivers. Moreover, the central processing unit (CU) utilizes remote radio units (RU)s belonging to the same operator, i.e., the trusted RUs, as well as the RUs belonging to other operators or private owners, i.e., the untrusted RUs. In order to preserve information privacy, we propose a coordinated jamming strategy, where the trusted RUs are enabled with full-duplex (FD) capability and transmit a coordinated jamming signal towards the exotic RUs and the IUs, while receiving and forwarding UL signal to the CU. An optimization problem is then formulated to maximize the sum uplink private information rate by jointly designing the fronthaul compression, as well as the information and jamming transmission strategies. Due to the intractability of the resulting mathematical problem, an iterative solution is proposed with convergence to a point satisfying the Karush-Kuhn-Tucker (KKT) optimality conditions. Numerical simulations illustrate a notable gain obtained via the proposed sharing mechanism under the consideration of information privacy.