Greater Connectedness in Remote Areas: A Ka-band Transceiver for Satellite Communications

TOKYO and SANTA CLARA, Calif., August 4, 2020 ---Scientists at Tokyo Institute of Technology and Socionext Inc. have developed a novel transceiver for enabling seamless communication between terrestrial platforms and satellites in the low, middle, and geostationary earth orbits. Among other things, this transceiver could bring Internet to people in remote rural areas and at sea.

We are living in an age where information and communications technologies have reached unprecedented levels of advancement. Yet bringing connectivity to remote locations, such as rural areas or the open sea, remains difficult. Satellite communication (SATCOM) is an attractive option for providing data links to such places; but for effective SATCOM, the right equipment must exist both in outer space and here on Earth.

At the forefront of research to achieve superior SATCOM solutions are scientists from Professor Kenichi Okada’s lab at Tokyo Institute of Technology (Tokyo Tech), who have developed a novel transceiver¹ for SATCOM using standard CMOS² technology. This transceiver operates in the “Ka band,” which, for SATCOM, means a 17–21 GHz frequency range for uplink (ground to satellite) and 27–31 GHz range for downlink (satellite to ground).

Their design carries a variety of features that sets itself apart from the competition. On the transmitter (TX) side, a high-quality-factor transformer is employed to achieve efficient power usage and high linearity in transmission, which results in lower distortion during data transfer. The receiver (RX) side features a dual-channel architecture with several added capabilities.

First, having two RX channels enables reception of signals from two satellites simultaneously. These signals are received in parallel using either two independent polarization modes or two different frequencies. In addition, the proposed design can perform adjacent-channel interference cancellation, which is the elimination of the  “contamination” on a signal received in one channel by another signal on an adjacent frequency band using information received at the other channel. This strategy increases the dynamic range of the system, thus allowing it to operate correctly even in less-than-ideal scenarios with increased noise and interference.

Both the TX and RX perform direct conversion of a signal; that is, the TX directly converts a baseband³ signal into a modulated⁴ signal and the RX performs the inverse process without additional intermediate frequency conversions, unlike the more commonly used superheterodyne receivers. This feature of the transceiver allows for a reduction of the overall complexity, size, and power consumption.

Tokyo Tech scientists created a prototype chip to test the actual performance of their design when using all the modulation schemes regulated by the SATCOM DVB-S2X standard. This includes high-order modulation techniques like 64APSK and 256APSK⁵, which provide fast data rates.

The performance test results are very promising, especially when compared with other existing SATCOM transceivers, putting this novel design on the map. Prof Okada remarks, “Our paper presents the first Ka-band SATCOM transceiver implemented using standard CMOS technology and designed for terrestrial platform communication with geostationary and low Earth orbit satellites.”

These orbits are at 35,786 km and 200–2,000 km, respectively. Communicating with satellites that far away from a 3 mm by 3 mm chip is certainly no simple feat.

For years, Prof Okada’s lab has been developing various types of state-of-the-art transceivers for next-generation technology, including 5G applications, Internet-of-Things-enabled devices, and low-power Bluetooth communications. This latest transceiver is another piece in the puzzle of enabling a seamless worldwide connectivity. “Satellite communication has become a key technology for providing interactive TV and broadband internet services in low-density, rural areas. Implementing Ka-band communications using silicon—CMOS technology in particular—is a promising solution owing to the potential for global coverage at low cost  using the widely available bandwidth.” Prof Okada says.

In an effort to improve the lives of people in the information age, researchers at Tokyo Tech continue to work toward advancing the speed of communication.

 

Technical Terms
¹Transceiver: A device capable of transmitting and receiving signals
²CMOS: Complementary metal-oxide-semiconductor; a modern type of fabrication process for transistors widely used for highly integrated circuitry
³Baseband signal: A signal in its “pure” form at its original frequency, without modulation
⁴Modulated signal: An encoded signal that carries all the information of a baseband signal, usually at a higher frequency so as to make it easier to transmit
⁵APSK: Amplitude and phase shift keying; a modulation technique where a baseband signal is encoded in both the phase and amplitude of a carrier signal

Reference

Authors:	Yun Wang1, Dongwon You1, Xi Fu1, Takeshi Nakamura1, Ashbir Aviat Fadila1, Teruki Someya1, Atsuhiro Kawaguchi1, Jian Pang1, Kiyoshi Yanagisawa1, Bangan Liu1, Yuncheng Zhang1, Haosheng Zhang1, Rui Wu1, Atsushi Shirane1, Shunichiro Masaki2, Daisuke Yamazaki2, Kenichi Okada1
Title of original paper:	A CMOS Ka-Band SATCOM Transceiver with ACI-Cancellation Enhanced Dual-Channel Low-NF Wide-Dynamic-Range RX and High-Linearity TX
Journal:	IEEE Radio Frequency Integrated Circuits Symposium 2020 — RFIC2020
Affiliations:	1Department of Electrical and Electronic Engineering, Tokyo Institute of Technology 2Socionext

*Corresponding author’s email: [email protected]