Each layer of the TCP/IP stack (Application, Transport, Network, Data Link and Physical) has established security and cryptography schemes except one, the Physical (PHY) layer. \tThe Application Layer \tUsers directly interface with this level. Applications include email clients, internet browsers, video conferencing. \tSecurity is provided by encrypting the data to be sent. Secure Real-time Transport Protocol (SRTP) is example protocol initiated at this layer. \tThe Transport Layer \tManages communications sessions between host and destination devices. \tTransport Layer Security protocol doesn’t exactly fit into the Transport layer as it is used by the user application, but it establishes a secure communication between the sender and receiver through a handshaking procedure. \tNetwork Layer \tIs responsible for routing IP data packets across the network. \tThe IPsec protocol provides data origin authentication, replay protection at this layer. \tData Link Layer \tControls access to the communication network. \tProtocols such as Wi-Fi Protected Access (WPA) provides security by only allowing access to the network for the MAC addresses that have been verified. \tPhysical Layer \tIs the physical (wireless, fiber optical, electrical) transmission of the data from the upper layers \tNo established security standard or protocol Physical Layer Security (PLS) has been an area of active research for wireless communication systems. Many of the potential solutions are multi-antenna-based utilizing spatial diversity of the physical medium. Transmit beamforming utilizes multiple antennas to direct a beam in a desired direction, reducing the SNR of an eavesdropper. This solution is especially attractive on mmWave networks because of the ability to create narrow beams from small antenna arrays.