Kaoru Yokoo

RF Chipset for Impulse UWB Radar Using 0.13-

A novel ultra-wideband impulse radar architecture for 24-GHz-band short-range radar was developed using 0.13-mum InP high electron-mobility technology. The transmitter part generates an extremely wideband impulse from a pulse generator and then filters it through a bandpass filter. The obtained impulse had a full width at half maximum of 9 ps. Its frequency spectrum spread from dc to over 40 GHz and achieved sufficient flatness in the target band. The power amplifier (PA) for the transmitter had a gain of 15 plusmn0.1 dB, and the low-noise amplifier (LNA) for the receiver had a gain of 40 plusmn1 dB and a minimum noise figure of 1.9 dB. The achieved flatness of integration gain including the PA, LNA, and RF switch was less than plusmn1.2 dB. These RF circuits with gain flatness make a simple matched filter configuration possible without the use of a conventional correlator composed of a local oscillator. An ultra high-speed sample and hold circuit having an ultra-long hold time of more than 3 ns was also developed to detect the output pulses from the matched filter

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A novel ultra wideband impulse radio architecture for 24 GHz-band short-range radar was developed using 0.13 mum InP-HEMT technology. The transmitter part generates an extremely wide band impulse from a pulse generator and then filters it by using a band pass filter (BPF). The obtained impulse shows a bandwidth of over 40 GHz and achieves flatness in the target band. The power amplifier (PA) for the transmitter has a gain of 15 plusmn 0.05 dB, and the low noise amplifier (LNA) for the receiver has a gain of 40 plusmn 1 dB. The achieved flatness of the integration gain including the PA, LNA, and RF-switch is less than plusmn 1.1 dB. These RF circuits with gain flatness make possible a simple matched filter configuration without the use of a conventional correlator composed of a local oscillator

InP-HEMT Technology

The aim of this paper is to propose a novel indoor positioning technique operated without any infrastructure by use of radar sensors. In this paper, the system which utilizes relative velocity measurements from Continuous Wave (CW) based radars is described as well as a combination of a radar and a gyro sensor. The former configuration results in 2.1 m error for 21 m total trajectory length and the latter has 11.6 cm error which can be improved down to 6.8 cm error for the same trajectory. The results are very promising for our objective application, infrastructure independent indoor localization for first-responders and robots.

An RF Chipset for Impulse Radio UWB Using 0.13 μm InP-HEMT Technology

The combination of Multiple-Input Multiple-Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM) technologies gives wireless communications systems the advantages of lower bit error rate (BER) and higher data rate in frequency-selective fading environments. However, the main drawbacks of MIMO systems are their high complexity and high cost. Therefore, antenna selection in MIMO systems has been shown to be an effective way to overcome the drawbacks. In this paper, we propose two receive antenna selection methods for a MIMO-OFDM system with radio frequency (RF) switches and polarization antenna elements at the receiver side, taking into consideration low computational complexity. The first method selects a set of polarization antenna elements which gives lower correlation between received signals and larger received signal power, thus achieves a lower BER with low computational complexity. The second method first selects a set of polarization antenna elements based on the criterion of the first method and another set of polarization antenna elements based on the criterion of minimizing the correlation between the received signals; it then calculates the signal-to-interference-plus-noise power ratio (SINR) of the two sets and selects a set with larger SINR. As a result, the second method achieves a better BER than the first one but it also requires higher computational complexity than the first one. We use the measured channel data to evaluate the performance of the two methods and show that they work effectively for the realistic channel.

Indoor Relative Localization with Mobile Short-Range Radar

This paper describes a localization technique to be used for a pasturing management system. Issues to be addressed are low energy consumption for battery operation and radio propagation degradation due to undulating lands in pastures. We decided to use received signal strength- (RSS-) based trilateration for low power, and to consider the topographical effect using particle filters (PF). To evaluate the proposed algorithm, an experimental campaign was conducted in a pasture with an area of 2 km2. The results show that the proposed algorithm improves the localization accuracy by 28% when compared with the least square (LS) algorithm, whereas plain PF increased it by 14%. These results show that our technique meets the requirements for pasture management.

Proposal of Receive Antenna Selection Methods for MIMO-OFDM System

Performance of a multiple input/multiple output (MIMO) system is largely degraded when it is equipped in mobile terminals or placed near a human body because radio waves are absorbed or shielded by the human body. This paper evaluates an antenna selection-based MIMO system under environments near human body. Each MIMO antenna branch at the receiver of the proposed MIMO system is equipped with several antennas, which have different characteristics such as polarizations and directional patterns, and the receiver selects one of them by radio frequency (RF) switches. A 2times2 MIMO propagation measurement at an indoor environment with the proposed antenna is conducted, and channel capacities and bit error rates (BERs) are evaluated by computer simulations with the measured channel data. From the results, the channel capacity is improved by more than 1.5 bit/sec/Hz when the proposed antenna is used near a human body. In addition, from the BER simulations that assume OFDM transmission IEEE802.11n, it is found that the received power is improved by more than 5 dB at cumulative distribution function (CDF) value of 0.5.

RSS-based localization considering topographical feature for pasturing

This paper describes a real-time performance evaluation of a receive antenna selection method for a spatial multiplexing multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system in a real environment. In this real-time performance evaluation, we employed a receive antenna selection method to select a suitable set of polarization antennas at the receiver side of the MIMO-OFDM system with low computational complexity. The receiver of the MIMO-OFDM system caught the preambles of the signal bursts to calculate the channel impulse responses and used them in calculating a cost function to decide a suitable set of polarization antennas. The results showed that the MIMO- OFDM system with the receive antenna selection method selected suitable sets of polarization antennas and achieved good performance.