(AGENPARL) – mer 10 luglio 2024 *Source*: Tokyo Institute of Technology
*Immediate release:* July 10, 2024 (Japan time)
*Headline*: Compact and Scalable Multiple-Input Multiple-Output Systems for
Future 5G Networks
*Sub-headline: * The proposed 28GHz beamformer shares radio frequency
elements for the highest area efficiency among multiple-input
multiple-output receivers
*(Tokyo, July 10)* A 28GHz time-division multiple-input multiple-output
(MIMO) receiver with eight radio frequency elements, each occupying just
0.1 mm², has been developed by researchers at Tokyo Tech using 65nm CMOS
technology. This innovative design reduces chip size for beamforming.
Achieving -23.5 dB error vector magnitude in 64-quadrature amplitude
modulation and data rates up to 9.6 Gbps, this receiver offers the highest
area efficiency and fastest beam switching among reported MIMO receivers.
To meet the growing need for data from applications like video streaming,
augmented reality, autonomous vehicles, and Internet of Things devices, 5G
New Radio and future beyond 5G technologies utilize multi-beam
multiple-input multiple-output to send and receive multiple streams of data
simultaneously. An essential component for effective MIMO operation is
beamforming. Beamforming adjusts the signals to focus them towards the
transmitters or receivers. This process improves signal quality and
minimizes interference. However, conventional analog beamforming MIMO
receivers require separate beamformers for each data stream, making it
challenging to implement in a millimeter wave MIMO system like a 28GHz MIMO
transceiver where the antenna pitch (the distance between antennas) is only
5 millimeters.
To address this, researchers led by Professor Kenichi Okada from Tokyo
Institute of Technology have proposed a novel technique called
time-division MIMO (TD-MIMO) beamformer that can support millimeter-wave
MIMO without the need for additional hardware. The study has been published
in the *Proceedings of the* *2024 IEEE VLSI Symposium* and presented
at the *2024
IEEE Symposium on VLSI Technology & Circuits*
, June 16–20 in Honolulu, USA.
“The major challenge with conventional millimeter-wave MIMO receivers is
that their area and power consumption increase linearly with the number of
MIMO streams they need to support. As a result, the chip size scales with
the number of MIMO streams. Therefore, more than three MIMO streams have
never been demonstrated for a 2D array,” explains Okada.
In MIMO systems, each antenna connects with every other antenna via a
network of radio frequency (RF) paths. The number of these paths is
determined by multiplying the number of MIMO streams by the number of
antennas. Therefore, increasing the number of data streams increases the RF
paths needed.
In TD-MIMO operation, an analog beamformer quickly switches the beam
pattern or direction of the receiver at very high speeds, allowing multiple
signals to use the same RF paths. After the beamforming process, a TD-MIMO
switch directs each MIMO stream to separate output ports, ensuring that the
signals do not interfere with each other.
This system uses fast-switching phase shifters which can adjust the signal
phase within 2.5 nanoseconds, and clock-based synchronization to control
the timing of the beam switching. This approach enables the TD-MIMO
receiver to support more data streams by simply increasing the clock
frequency, ensuring scalable data transmission without increasing the size
of the chipset.
Researchers developed a 3mm x 2mm TD-MIMO receiver using 65nm CMOS
technology consisting of 8 RF elements to handle four separate 5G New Radio
data streams across a 400MHz channel bandwidth using 64-quadrature
amplitude modulation (QAM). The signals pass through a Wilkinson power
combiner to a TD-MIMO switch, which separates them into four paths. Each RF
element features a noise-cancelling amplifier and a fast phase shifter. A
variable gain amplifier and a retiming circuit keep the system in sync by
ensuring the switching occurs accurately (refer to Figures 1 and 2).
The receiver successfully handled 5G-compliant MIMO signals from a Keysight
arbitrary waveform generator transmitted by horn antennas in four
directions. It achieved -23.5 dB error vector magnitude in 64-QAM and a
rapid Nyquist-rate beam switching time of 0.15 ns, enabling data rates up
to 9.6 Gbps across the four-stream MIMO configuration.
“This work realizes highest data rates with highest area efficiency among
listed MIMO receivers,” says Okada. With each RF element occupying just 0.1
mm2, the proposed chipset can pave the way to smaller and more compact
efficient, scalable, multi-beam MIMO systems for high-speed data
transmission.
*Reference*
Conference:
The 2024 IEEE Symposium on VLSI Technology & Circuits
Session:
C9 Wireless Transceivers (June 18, 5:05 PM, Honolulu, USA, local time)
Session title
A 28GHz 4-Stream Time-Division MIMO Phased-Array Receiver Utilizing
Nyquist-Rate Fast Beam Switching for 5G and beyond
Authors:
Yi Zhang1, Minzhe Tang1, Jian Pang1, Zheng Li1, Dongfan Xu1, Dingxin Xu1,
Yuncheng Zhang1, Kazuaki Kunihiro1, Hiroyuki Sakai1, Atsushi Shirane1, and
Kenichi Okada1*
Journal:
*Proceedings of the 2024 IEEE VLSI Symposium*
Affiliations:
1Department of Electrical and Electronic Engineering, Tokyo Institute of
Technology, Japan
*Figure 1 file: Figure 1**. Title: * The block diagram of the 28 GHz
beamformer designed without frequency-converting components
*Figure 1**. Caption:* A 3-stage 8-to-1 Wilkinson power combiner combines
the beams, which are then separated to respective outputs by a TD-MIMO
switch. An H-tree network distributes the synchronization clock to each
receiver element, with DTCs in the clock distribution network for precise
timing calibration.
*Figure 1 file (jpg): *
https://tokyotech.box.com/s/n98uea7mc7tc630qa7i2qxjq187l0hjg
*Figure **2. Title : * Chip micrograph and the photo of the printed circuit
board (PCB) of the proposed TD-MIMO receiver
*Figure 2 caption:* The TD-MIMO receiver is fabricated using a common 65nm
CMOS process making it suitable for scalable production. The PCB has four
layers and integrates a 1 by 8 antenna array in the bottom layer.
*Figure 2 file (jpg)*
https://tokyotech.box.com/s/w4rm4xvvqkhuxxmll0k0nzujhpkth77x
For more information, please contact us.
*Contact: *Emiko Kawaguchi, Public Relations Department, Tokyo Institute
*About Tokyo Institute of Technology*
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leading university for science and technology in Japan. Tokyo Tech
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ingenuity and innovation,” the Tokyo Tech community strives to contribute
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mission of “Advancing science and human wellbeing to create value for and
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