THz chip-to-chip communication: Channel characterization and RFID tag design

Abstract

The ever-growing demand on the capacity of wireless communication indicates that data rates will reach Terabit-per-second (Tbps) in the coming years. To achieve Tbps data rates, THz frequency bands need to be explored. Our research address two problems that need to be solved to enable Tbps data rates: 1) characterize and model wireless channels in data centers and 2) design THz antenna-less RFID tags that can further reduce the device size by not using antennas and have potential to attain ultra high data rates. Existing wired data centers are facing challenges such as increased assembly cost, maintenance cost, operating cost, service time, and decreased cooling efficiency due to the usage of cables. On the other hand, existing RFID technologies have limited data rates due to limited bandwidth and have inflexible form factor since the device size is mainly dominated by the antennas. Our first objective is to characterize channel properties and develop statistical channel models for THz propagation in a data center environment. Various propagation scenarios such as line-of-sight (LoS) link, non-LoS (NLoS) link using existing materials in a data center to redirect the beam, and obstructed-LoS/-NLoS links with common objects in data centers (cables and server racks mesh doors) serving as obstruction. Propagation channel parameters such as pathloss and root-mean-squared delay spread have been analyzed and cluster-based modeling has been implemented in the aforementioned scenarios. The second objective is to develop the THz antenna-less RFID tag. A circuit impedance model is developed to explain the modulation mechanism of the antenna-less backscatter radio generated by the switching transistors inside digital circuits. A propagation model has been developed for the assessment of link budget and validated with measurements. Several RFID applications have been implemented to demonstrate that the antenna-less RFID tag has very flexible carrier frequency selection (5.8-300 GHz) and bit configuration (static and dynamic IDs). This work provides other researchers guidelines on design approach and system planning for THz wireless data centers and THz antenna-less RFID tags.