Yozo Shoji

Millimeter-wave remote self-heterodyne system for extremely stable and low-cost broad-band signal transmission

We have developed a millimeter-wave remote self-heterodyne transmission system that enables extremely stable and low-cost broad-band transmission in the millimeter-wave band. The system was applied to a 60-GHz-band transmission system for the first time. The transmitter of the developed system transmits RF modulated signals and a local oscillation signal simultaneously, and the receiver detects these signals by using a square-law-type detection technique, thus creating a very stable and low phase-noise millimeter-wave transmission link without the use of an expensive and more advanced frequency-stabilization technology. Since the receiver no longer requires a millimeter-wave oscillator for frequency conversion, the devices used in this system can be miniaturized and the cost of the system can be reduced. This paper discusses the performance of the developed system in terms of its phase-noise degradation and carrier-to-noise power ratio (CNR). We also discuss the optimal transmitter design to obtain the maximum CNR. Using our miniaturized monolithic millimeter-wave integrated-circuit-based 60-GHz-band experimental system, we demonstrate that our millimeter-wave transmission link is completely free of phase-noise and frequency-offset degradation due to the use of a millimeterwave local oscillator. We show that equal transmission-power distribution between the RF signal and local carrier gives the maximum CNR under the transmission-power-limited conditions. Also, we demonstrate that QPSK-modulated satellite broadcast multichannel video signals with a 300-MHz bandwidth, in total, can be successfully transferred over a distance of 8 m.

CATT: potential based routing with content caching for ICN

Information Centric Networking (ICN) has shown possibilities to solve several problems of the Internet. At the same time, some problems need to be tackled in order to advance this promising architecture. In this paper we address two of the problems, namely routing and content caching. For the routing, we introduce the Potential Based Routing (PBR) to achieve several design goals such as availability, adaptability, diversity, and robustness. In addition, we examine the performance of a random caching policy which can be a promising candidate for ICN. The integrated system of both PBR and a caching policy is named the Cache Aware Target idenTification (CATT). Simulation results demonstrate that PBR with replications located on less than 1% of total nodes can achieve a near optimal routing performance (close to the shortest path routing) even though a request message is randomly forwarded.

Polarization measurements through space-to-ground atmospheric propagation paths by using a highly polarized laser source in space

The polarization characteristics of an artificial laser source in space were measured through space-to-ground atmospheric transmission paths. An existing Japanese laser communication satellite and optical ground station were used to measure Stokes parameters and the degree of polarization of the laser beam transmitted from the satellite. As a result, the polarization was preserved within an rms error of 1.6 degrees, and the degree of polarization was 99.4+/-4.4% through the space-to-ground atmosphere. These results contribute to the link estimation for quantum key distribution via space and provide the potential for enhancements in quantum cryptography worldwide in the future.

A design of single carrier based PHY for IEEE 802.15.3c standard

This paper proposes an air interface for ultra high-speed millimeter wave (60 GHz) systems which have been under standardization process at IEEE 802.15.3c: the proposed channel plan permits ease of portable device implementation employing the major crystal oscillator used in CDMA cellar phones. The proposed transmission modes offer much greater scalability, covering from several tens Mbps to over 4 Gbps. The proposed preamble employs Golay codes, providing sufficient robustness against wireless environment being subject to the characteristics of millimeter wave with reduced hardware complexity. Common mode is a novel technique to communicate with single carrier (SC) and OFDM camps with multi rates up to around 1.5 Gbps. This technique gives the proposed systems easy expandability from SC to OFDM or other SCs and vice versa.

Channel Model for Millimeter Wave WPAN

Proposed PHY layer schemes are evaluated using the channel model that corresponds to each usage model in IEEE802.15.3c standardization process. NICT has contributed TSV model to the IEEE802.15.3c channel model subgroup. The model developed by NICT has been selected as the model for the evaluation of mandatory simulations. This paper describes the channel model for millimeter-wave band developed for the TG3c.

Proposal of novel statistic channel model for millimeter wave WPAN

A statistic channel model, TSV-model: Shoji, Sawada, Saleh (Triple S), and Valenzuela model, was newly developed to design 60-GHz band wireless personal area network systems. Shoji and Sawada newly developed a statistic two- path channel model to express sensitive device- position-dependent fading inherent to mmW WPAN system and combined it with the statistic S-V model which had been commonly used in some IEEE802.15 standardization groups. The mathematical expression and characteristics of the developed TSV-model are described in detail, and the validity of the proposed channel model is proved by measuring indoor propagation characteristics in an office environment.

A Wireless Video Home-link Using 60GHz Band: Concept and Performance of the Developed System

A concept and requirements of a millimeter-wave video transmission system as a wireless home-link using 60-GHz band are described. This system can transmit broadcast television (TV) signals from TV antennas to TV set and thus can be regarded as a substitute for a feeder line. The feasibility study by investigating the systems CNR and SNR performances using MMIC-based experimental setup is also described.

A Modified SV-Model Suitable for Line-of-Sight Desktop Usage of Millimeter-Wave WPAN Systems

A modified Saleh-Valenzuela (SV) model, which is useful in designing a millimeter-wave WPAN (mmW WPAN) system for line-of-sight (LoS) desktop environments, is proposed. It is demonstrated that a well-known two-path model component is dominantly observed in a typical LoS desktop channel along with the components of the other non-line-of-sight (NLoS) paths. Then, the deterministic two-path model is extended to a statistical two-path model by introducing random variables for the antenna position and merging with the conventional SV-model which is suitable to express NLoS path components. The proposed channel model parameters are extracted in a typical LoS desktop environment, and then the cumulative distribution of total path power gain is discussed using a simulation technique that assumes a specific antenna location scenario. It is shown that the cumulative distribution of total path power gain obtained using the proposed model is useful to estimate the outage probability of the mmW WPAN link.

70-GHz-Band OFDM Transceivers Based on Self-Heterodyne Scheme for Millimeter-Wave Wireless Personal Area Network

70-GHz-band orthogonal frequency-division multiplexing (OFDM) transceivers were developed by combining self-heterodyne transmission with two-element diversity reception. The transceivers were used to study and demonstrate a millimeter-wave wireless personal network that enables cost-effective broadband data transmissions in a multipath channel environment. A 100-MHz sampling OFDM modulator/demodulator was developed for the baseband part. It has a payload data rate of 100 Mb/s using quadrature phase-shift keying (QPSK) modulation and a coding rate of 3/4 (many other modulations and coding rate are available). The bit error rate was experimentally evaluated when a pair of devices was placed on a wooden table under line-of-sight path conditions. The results showed that the combined use of the self-heterodyne technique and two-element diversity receiver successfully avoids serious signal fading at unpredictable transmission distances. The transceiver with QPSK modulation and coding rate of 1/2 for forward error correction achieves error-free data transmission over a distance of up to 3.4 m. In addition, a successful transmission in 64 quadrature amplitude modulation mode was demonstrated, although the communication range was quite short

Millimeter-Wave Fiber-Fed Wireless Access Systems Based on Dense Wavelength-Division-Multiplexing Networks

This paper describes new 60-GHz-band bidirectional fiber-fed wireless access systems, which provide simple antenna base-station architecture and full compatibility with dense wavelength-division multiplexing (DWDM) fiber-optic networks. For downlink millimeter-wave signal generation, the proposed scheme utilizes uplink optical transmitters as downlink optical heterodyne sources, which promises wavelength allocations of downlink and uplink signals that are fully compatible with those of DWDM networks. The frequency instability and poor phase-noise characteristics of these optically heterodyned signals do not affect transmission quality at all by using self-heterodyne wireless transmission techniques. Experimental results demonstrate that the proposed scheme provides not only strong immunity to phase-noise degradation coming from both fiber and millimeter-wave links, but also less sensitivity to fiber transmission loss than conventional remote optical heterodyne approaches. With the help of these attractive features, we successfully demonstrate both downlink and uplink orthogonal frequency-division multiplexing data transmissions in both 10-km fiber-optic and 60-Hz links.