  Device-to-device (D2D) aided beamforming for coded caching is considered in
finite signal-to-noise ratio regime. A novel beamforming scheme is proposed
where the local cache content exchange among nearby users is exploited. The
transmission is split into two phases: local D2D content exchange and downlink
transmission. In the D2D phase, users can autonomously share content with the
adjacent users. The downlink phase utilizes multicast beamforming to
simultaneously serve all users to fulfill the remaining content requests. We
first explain the main procedure via two simple examples and then present the
general formulation. Furthermore, D2D transmission scenarios and conditions
useful for minimizing the overall delivery time are identified. We also
investigate the benefits of using D2D transmission for decreasing the
transceiver complexity of multicast beamforming. By exploiting the direct D2D
exchange of file fragments, the common multicasting rate for delivering the
remaining file fragments in the downlink phase is increased providing greatly
enhanced overall content delivery performance.
