Secure communication in underlay spectrum sharing multi-user massive multiple-input multiple-output systems with active eavesdropping is investigated. The primary base-station (PBS) shares its licensed the secondary (SBS), which constrains transmit power subject to a interference temperature. eavesdropper contaminates uplink pilots an attempt intercept confidential downlink transmissions toward legitimate primary/secondary user nodes (PUs/SUs). achievable PU/SU rates, rates leaked into...

The achievable secrecy rates for a cell-free massive multiple-input multiple-output (MIMO) in the presence of single-antenna active eavesdropper are derived and compared with that co-located MIMO. contaminates uplink channel estimates at access points (APs), downlink precoders APs constructed based on this contaminated estimates. Hence, inadvertently beamform confidential information towards during transmission. legitimate user nodes leaked into estimated/imperfect state finite infinite...

In this paper, the achievable secrecy rate of a relay-assisted massive multiple-input multiple-output (MIMO) downlink is investigated in presence multi-antenna active/passive eavesdropper. The excess degrees-of-freedom offered by MIMO base-station (BS) are exploited for sending artificial noise (AN) via random and null-space precoders. An active eavesdropper contaminates uplink channel estimates pilot sequences identical to those legitimate users/relay. This contamination makes BS implicitly...

In this paper, secure transmission strategies for the relay-assisted massive multiple-input multiple-output (MIMO) downlink are investigated by using artificial noise (AN) generation and exploiting excess degrees-of-freedom through random null-space based precoders. The achievable rate expressions derived estimated channel state information, hence, detrimental effects of estimation errors in designing precoders quantified. Specifically, secrecy at relayed user nodes is closed-form, thereby,...

In this paper, the achievable secrecy rates are derived for relay-assisted massive multiple-input multiple-output (MIMO) downlink with limited number of radio frequency (RF) chains at base-station (BS). Two hybrid precoder designs investigated dual-hop transmission information and artificial noise. channel estimation techniques proposed. Thereby, rate gap between precoding full-dimensional digital is quantified imperfect state information. Our analysis reveals that proposed precoders can...

Pilot contamination attacks in training-based massive multiple-input multiple-output systems with limited radio-frequency chains are investigated. A lower bound for the achievable secrecy rate presence of a multi-antenna active eavesdropper is derived closed-form. Thereby, loss due to over passive eavesdropping quantified. Moreover, hybrid precoding full-dimensional digital derived.