A Two-Hop MIMO Relay Architecture Using LTE and Millimeter Wave Bands in High-Speed Trains

In this paper, a novel two-hop relay architecture using mobile relay nodes (MRN) technology for high-speed trains is presented. In this architecture, a long-term evolution advanced (LTE-A) link in sub-6 GHz bands is established between the Donore-NB (DeNB) and the MRNs mounted on the roof of the train and another in millimeter Wave (mmWave) bands between the MRN and the user equipment (UE) terminals inside the train. Moreover, the multiple-input multiple-output (MIMO) channel is exploited between the DeNB and the UEs to enhance channel capacity. Different relay structures-several relays in a train carriage and a single relay with multiple antennas-and different types of relays-amplify-and-forward and decode-and-forward (DF)-are studied. Ultimately, performance analysis is studied and discussed by means of a downlink-level simulator with accurate channel models. Furthermore, multiuser transmission and conventional user scheduling algorithms are added to obtain a more realistic simulator. Anew algorithm for one of the structures and the DF relay is proposed. This paper will examine how to provide broadband data access to train passengers in high-speed environments by validating a new architecture, which takes advantage of MIMO techniques, mobile relays, and millimeter bands.