Security is one of main concerns in communications, and radio devices and nodes can be easily targeted through jamming attacks even considering the sophisticated security features of 5 G systems. This work presents a comprehensive system based on O-RAN that monitors the spectrum, detects the jamming signal, classifies it, and provides mitigation actions. At the core of our system is an xApp suite that interconnect four xApps, each of them implementing one functionality. We have validated the performance of the xApp suite by implementing it in a 5G O-RAN testbed based on open source libraries and general purpose hardware.

The last years have seen an unprecedented interest in the utilization of aerial platforms not only to support applications (e.g. monitoring) but also to assist in relaying signals from terrestrial networks. In this new paradigm, it is capital to have an estimation of the communication channel, which is quite different from the terrestrial channel. This paper presents a channel model for air-to-ground (A2G) communications based on a measurement campaign over an in-service 5G NSA (non-standalone) network, whic allows for future investigations to have an estimate of the path loss in similar environments, and provides a full detail of the measurements

Aeronautical communications are expected to increasingly demand spectrum in the next years. Given the endemic scarcity of spectrum, both the opportunistic use of licensed bands and carrier aggregation enable aeronautical systems to accommodate higher data rates and more aircrafts. We study dynamic spectrum allocation for air-to-ground (A2G) transmissions when carriers can be aggregated to form larger channels with complete and incomplete information: the aircrafts might not reveal their available channels for security reasons as it would expose their location. The single and multiple ground station scenarios are analyzed. Semi-distributed algorithms are proposed to deal with the incomplete information case for both scenarios, exhibiting a very good tradeoff between performance and complexity.

The trend in wireless networks is that several wireless radio access technologies (RATs) coexist in the same area, forming heterogeneous networks in which the users may connect to any of the available RATs. The problem of associating a user to the most suitable RAT, known as network selection problem (NSP), is of capital importance for the satisfaction of the users in these emerging environments. However, also the satisfaction of the operator is important in this scenario. In this work, we propose that a connection may be served by more than one RAT by using multi-RAT terminals. We formulate the NSP with multiple RAT association based on utility functions that take into consideration both user’s satisfaction and provider’s satisfaction. As users are characterized according to their expected quality of service, our results exhaustively analyze the influence of the user’s profile, along with the network topology and the type of applications served.

We consider the downlink coordinated beamforming problem in a cellular network in which the base stations (BSs) are equipped with multiple antennas and each user is equipped with a single antenna. The BSs cooperate in sharing their local interference information, and they aim to maximize the sum-rate of the users in the network. A decentralized interference pricing beamforming (IPBF) algorithm is proposed to identify the coordinated beamformer, where a BS is penalized according to the interference it creates to its peers. We show that the decentralized pricing mechanism converges to an interference equilibrium, which is a KKT point of the sum-rate maximization problem. The proofs rely on the identification of rank-1 solutions of each BSs' interference-penalized rate maximization problem. Numerical results show that the proposed iterative mechanism reduces significantly the exchanged information with respect to other state-of-the-art beamforming algorithms with very little sum-rate loss. The version of the algorithm that limits the coordination to a cluster of base stations (IPBF-L) is shown to have very small sum-rate loss with respect to the full coordinated algorithm with much less backhaul information exchange.