Revolutionary transceiver with quick beam switching takes 5G to the subsequent degree
Scientists from Tokyo Institute of Technology (Tokyo Tech) and NEC Corporation are jointly developing a 28 GHz phased array transceiver that supports efficient and reliable 5G communication. The proposed transceiver surpasses previous designs in several respects in that it adopts a fast beam switching and leakage cancellation mechanism.
With the advent of innovative technologies such as the Internet of Things, Smart Cities, Autonomous Vehicles and Smart Mobility, our world is on the brink of a new age. This encourages the use of millimeter wave bands, which have a much wider signal bandwidth, to accommodate these new ideas. By using these millimeter waves and multiple-in-multiple-out (MIMO) technology, 5G can offer data rates of over 10 Gbit / s – a technology that uses multiple transmitters and receivers to transmit more data at the same time.
Large-scale phased array transceivers are critical to implementing these MIMO systems. While MIMO systems increase spectral performance, large-scale phased array systems face several challenges, such as increased power dissipation and implementation costs. One such critical challenge is the latency caused by beam switching time. Beam switching is an important feature that enables the most optimal beam to be selected for each terminal. A design that optimizes beam switching time and equipment costs is therefore the order of the day.
For this reason, scientists from Tokyo Institute of Technology and NEC Corporation in Japan have jointly developed a 28 GHz phased array transceiver that supports high-speed beam switching and high-speed data communication. Their results will be discussed at the 2021 Symposia on VLSI Technology and Circuits, an international conference that examines emerging trends and innovative concepts in semiconductor technology and circuits.
The proposed design enables dual polarized operation in which data is transmitted simultaneously by horizontally and vertically polarized waves. A problem with these systems, however, is the loss of cross polarization, which leads to signal degradation, particularly in the millimeter wave band. The research team delved into the topic and developed a solution. Prof. Kenichi Okada, who led the research team, says: “Fortunately, we were able to develop a method of detecting and suppressing cross-polarization that allowed us to suppress the leaks in both transmit and receive modes.”
A critical feature of the proposed mechanism is the ability to achieve low latency beam switching and high accuracy beam steering. Static elements control the building blocks of the mechanism, while on-chip SRAM is used to store the settings for different beams (Figure 1). This mechanism results in fast beam switching with extremely low latency. It also enables quick toggling between the transmit and receive modes due to the use of separate registers for each mode.
Another aspect of the proposed transceiver is its low cost and small size. The transceiver has a bidirectional architecture that enables a smaller chip size of 5 × 4.5 mm2 (Figure 2). With a total of 256 sample beam settings stored in the on-chip SRAM, a beam switching time of only 4 nanoseconds was achieved! The error vector size (EVM) – a measure for quantifying the efficiency of digitally modulated signals such as quadrature amplitude modulation (QAM) – was calculated for the proposed transceiver. The transceiver was supported with EVMs of 5.5% in 64QAM and 3.5% in 256QAM.
Compared to modern 5G phased array transceivers, the system offers faster beam switching time and excellent MIMO efficiency. Okada is optimistic about the future of the 28 GHz 5G phased array transceiver. He concludes: “The technology we developed for the 5G NR network supports the streaming of data with high data volumes with low latency. Thanks to its fast beam switching, it can be used in scenarios where enhanced multi-user experience is required on stage for a wide variety of applications, including networking machines and building smart cities and factories. “
This research is supported by Japan’s Ministry of Internal Affairs and Communications (JPJ000254).
Authors: Jian Pang, Zheng Li, Xueting Luo, Joshua Alvin, Kiyoshi Yanagisawa, Yi Zhang, Zixin Chen, Zhongliang Huang, Xiaofan Gu, Weichu Chen, Yun Wang, Dongwon You, Zheng Sun, Yuncheng Zhang, Hongye Huang, Naoki Oshima, Keiichi Motoi, Shinichi Hori, Kazuaki Kunihiro, Tomoya Kaneko, Atsushi Shirane and Kenichi Okada
Session: Session 11 Advanced Wireless for 5G, C11-2 (June 17: 50 JST)
Session Title: A 28 GHz, fast beam switching phased array transceiver that supports cross polarization leakage self-canceling
Conference: 2021 symposia on VLSI technology and circuits
Affiliations: Tokyo Institute of Technology, NEC Corporation
About the Tokyo Institute of Technology
Tokyo Tech is at the forefront of research and higher education as the leading science and technology university in Japan. Tokyo Tech researchers excel in areas that range from materials science to biology, computer science and physics. Tokyo Tech was founded in 1881 and is home to over 10,000 undergraduate and graduate students annually who develop into science leaders and some of the most sought-after engineers in the industry. The Tokyo Tech Community embodies the Japanese philosophy of “Monotsukuri”, which means “technical ingenuity and innovation,” and strives to contribute to society through effective research.
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