Propagation characteristics in an underground shopping area for 5‐GHz‐band wireless access systems

5‐GHz‐band wireless access systems, such as the RLAN (Radio Local Area Network) system of IEEE 802.11a, HiperLAN/2, HiSWANa, and AWA, are deployed for indoor use at transmission rates over 20 Mbps. These 5‐GHz access systems are expected to extend service areas from the office to the so‐called “hot spots” in public areas. Underground shopping malls are one type of service area where the application of such nomadic wireless access service can be expected. In order to design radio zone configurations, it is necessary to know broadband propagation characteristics of an underground mall environment even if results obtained by previous measurements in the narrow band are available. This paper presents results of an experimental study on the propagation characteristics for broadband wireless access systems in an underground mall environment. First, broadband propagation path losses are measured and formulated considering the shadowing by human body. A ray trace simulation is used to clarify the basic propagation mechanism in such a closed environment. Next, it was determined that values of the delay spread at different distances during rush hour periods did not exceed 65 ns, which is lower than the permitted maximum value of the present 5‐GHz systems. The final conclusion is that the above propagation characteristics corroborate results of transmission tests carried out by using the AWA equipment. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(3): 55–64, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20059     

The design of linear and circular polarization for dual band microstrip slot antenna

This paper presents a lightweight antenna for wireless communication systems. The proposed antenna has been designed to be a dual‐band and dual‐polarized antenna by using a right‐angled slot structure fed a by microstrip line. The designed antenna is composed of three right‐angled slot radiators on the ground plane. The first two radiators are right‐angled slots of similar scale which are added to generate circular polarization at 4.95 GHz, while the last one has been designed for linear polarization at 2.45 GHz. Furthermore, in order to achieve dual‐band operation and dual polarization with good matching, a special arrangement is proposed. The results of simulation and measurements such as return loss, axial ratio, and radiation patterns are shown at the resonant frequencies of 2.45 and 4.95 GHz. Details of the experimental results are presented and discussed. In addition, the presented antenna can operate and cover the applications of a wireless local area network (WLAN IEEE 802.11 a/b/g/j/n). © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

数字实景游戏中的智能红外激光枪系统设计与实现

将对实景数字游戏智能红外激光枪系统的设计和实现做全面的介绍,完整地分析智能红外激光枪系统的控制方法.系统通过建立1个符合IEEE802.11b/g协议的无线局域网平台,来实现对激光枪对战的后台控制,用凌阳SPCE061A单片机和无线局域网模块实现通信数据的编解码、语音处理和网络互联.红外激光枪采用980m的红外半导体激...     

An intelligent MPEG rate control in 2.4 GHz frequency

Transmitting Moving Picture Expert Group (MPEG) Variable Bit Rate (VBR) video stream over 2.4 GHz wireless frequency demands a large bandwidth and may result in data loss and delay, because of excessive fluctuation in bit rate. Transmission over 2.4 GHz frequency further causes uncertainty due to interferences by other wireless devices in the same frequency band and/or common dynamic channel noises. As a result, an intelligent system has been developed for MPEG video transmission over 2.4 GHz frequency band. A novel fuzzy controller automatically determines the quantization scale for each Group Of Picture (GOP) of the encoder during the transmission period. Moreover, a fuzzy controller and a neural‐fuzzy controller stream the MPEG video data to conform to the current condition of dynamic wireless channel to maintain image quality during the transmission. In the intelligent system, rather than choosing the parameters associated with a given membership function arbitrarily, these parameters are chosen as such to tailor the membership functions to the desired input/output data. The intelligent system computes and trains the system in such a way that its output will be equal to the desired value. Computer simulation results demonstrate that the proposed intelligent technique increases transmission rate and reduces data loss, excessive delay and image quality degradation as compared with a conventional video transmission over 2.4 GHz frequency band. Copyright © 2009 John Wiley & Sons, Ltd.     

Examination of the dual‐band microwave wireless access system using radio on fiber technique

The Radio on Fiber (ROF) technique has great potential in wireless communication systems. In this paper, we report on a fundamental examination of microwave wireless access systems based on Radio on Fiber. First, we designed and constructed examination systems by applying dual band (2.4 and 5 GHz) multiservice transmission systems and confirmed that there was sufficient performance through a transmission experiment. Then, application of FP‐LD (Fabry Perot Laser Diode) was considered in order to reduce the system cost, and for the most part degradation of the transmission characteristics was not observed when FP‐LD was used. Finally, a BIDI (bidirectional) module which integrated LD and PD within one package was made to further reduce costs. By measuring the transmission performance, applying the BIDI module to ROF systems was shown to be effective. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(4): 32–40, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20471     

A wideband low‐spur 0.18‐µm CMOS phase‐locked loop with bandwidth calibration

This paper presents a 0.18‐µm complementary metal‐oxide‐semiconductor wideband phase‐locked loop with low reference spurs. The dual‐level charge‐pump current calibration technique is proposed to maintain a constant loop bandwidth for wide operation frequency range and achieve low reference spurs. The first level charge‐pump current calibration is seamlessly incorporated in the automatic frequency band hopping control and the mechanism also ensures enough negative transconductance for the voltage‐controlled oscillator to function throughout the whole frequency range. The charge‐pump current mismatch is calibrated by the second level charge‐pump current calibration combined with the pulse‐width scaling technique. The operation frequency range of the phase‐locked loop covers from 4.7 GHz to 6.1 GHz. The measured phase noise is?116 dBc/Hz at 1‐MHz offset and the reference spurs are below?66.8 dBc. Copyright © 2015 John Wiley & Sons, Ltd.     

A 0.15‐μm CMOS baseband LSI employing sleep mode with clock‐offset compensation for M2M wireless sensor networks

This paper describes a wireless baseband large‐scale integration (LSI) that contains a sleep management circuit. The sleep manager performs the sleep‐clock offset compensation and enables a wireless terminal (WT) with a typical crystal oscillator (XO) to remain in sleep mode for a long period while maintaining synchronization with the access point. Lab experiments show that the sleep period reaches 512 s and that, with intermittent operation, the WT maintains synchronization with the access point for 10 days. The LSI's average current consumption is as low as 11 μA for a 128‐s sleep period. A wakeup detection circuit is also implemented in the LSI. This circuit performs paging control instead of a microprocessor unit (MPU) and this helps to reduce current consumption in the MPU and the flash read only memory (ROM). The single‐chip baseband LSI is fabricated using 0.15‐μm CMOS technology. It is 4.6 mm × 4.2 mm in area and consumes 4.0 μA for sleep operation. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Design and simulation of novel amplifier‐based mixer for ISM band wireless applications

This letter describes a low‐voltage low‐power (LV‐LP) 2.4‐GHz mixer for Industrial, Scientific and Medical (ISM) band wireless applications. The approach is based on a two‐stage amplifier, and the Gilbert switch stage is inserted between the two amplifier stages. The proposed amplifier‐based mixer delivers a remarkable conversion gain of 13 dB with a local oscillator (LO) power of 7 dBm, while consuming only 1.05‐mW DC power from a 0.8‐V supply voltage. The input‐referred third‐order intercept point (IIP3) of the mixer is 3.82 dBm, and the chip area is only 0.429 mm². The results indicate that this mixer is suitable for the low‐voltage low‐power applications. Copyright © 2014 John Wiley & Sons, Ltd.     

Design of a novel adder‐less Barker matched filter for RFID

Radio frequency identification (RFID) is the utilization of the radio frequency for the purpose of identification. RFID is lagging behind due to vendor specific solutions and excessive implementation cost. A Wireless Fidelity (WiFi) compatible IEEE 802.11 RFID tag can overcome these limitations. IEEE 802.11 utilizes Direct Sequence Spread Spectrum (DSSS) technique and a matched filter is a vital block in a DSSS system. A low‐power and low‐area novel adder‐less Barker matched filter is proposed in this paper by eliminating the conventional multiple multiplications. The matched filter designed in 0.18 µm CMOS technology achieves average and maximum power consumption of 33.747 μW and 8.08 mW, respectively and chip area of 0.41184 mm² only. The simulation result shows the correct matching of data against the threshold value. Compared with the conventional matched filter, the design achieves 25% power reduction (maximum power) and 51% chip area reduction. Therefore, the design will help to implement a low‐power matched filter for IEEE 801.11 compatible RFID tag. Copyright © 2013 John Wiley & Sons, Ltd.     

An access method using fixed backoff for wireless LANs

In a wireless LAN, since two or more terminals randomly access a signal channel, frame collisions might occur. Under the standard IEEE 802.11 protocol, to avoid collisions, each terminal sets a random backoff before frame transmission. Although this measure avoids collisions, it results in useless standby duration and low throughput. To solve that problem, this paper proposes a media access method which has a fixed backoff after a successful transmission. It is shown by simulation that the proposed method reduces frame collisions and improves throughput. Furthermore, our method reduces the frame loss probability and the file transfer delay. 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 173(3): 30–39, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.21044     

Design of smiling‐face‐shaped band‐notched UWB antenna

A novel smiling‐face‐shaped band‐notched ultra‐wideband (UWB) antenna is designed in this paper. First, antenna bandwidth is broadened by adding a pair of small semi‐circular stubs (ears) and etching a pair of symmetrical C‐shaped slots (eyes), a triangular slot (nose), and a U‐shaped slot (mouth) on the patch. Second, by adjusting the length of the ground plane and creating a stepped slot on the ground plane, antenna bandwidth covers 3–12 GHz. Third, a pair of L‐shaped slots (hands) is etched on the ground plane to create a notch, which can effectively suppress the interference signal in worldwide interoperability for microwave access (WiMAX) (3.4–3.6 GHz) and satellite C band (3.7–4.2 GHz). Lastly, the proposed antenna is fabricated and measured. The measured results indicate the proposed antenna has good performance and can be widely used in UWB systems. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Proposal of over 100‐GHz band waveguide switch

A filter bank consisting of switches and band‐pass filters is one method for configuring a spectrum analyzer preselector. A long‐life switch with high isolation is key to this development. We propose a novel horizontal‐moving waveguide switch designed for easy addition of ports compared to commercial rotating switches. The switch has a small gap between the fixed and moving parts with the gap surrounded by chokes. This configuration offers high isolation and long life. It also reduces the size of the filter bank. This paper describes 2 proposed switch prototypes for frequency ranges from 90 to 140 GHz and from 255 to 315 GHz. The measured switch isolation is better than 50 dB and the insertion loss is less than 3 dB for both prototypes.     

A linearized and low noise CMOS mixer with B‐type amplifier‐based sub‐harmonic balun

A low noise and high linearity down‐conversion CMOS mixer for 2.4‐GHz wireless receiver is presented in this paper. Using a sub‐harmonic balun with a simple but effective B‐type amplifier, the local oscillator frequency required for this mixer has been reduced by half, and the input local oscillator signal could be single‐ended rather than differential, which simultaneously simplifies the design of local oscillator. A distortion and noise cancelation transconductor in association with current bleeding technique is employed to improve the noise and linearity of the entire mixer under a reduced bias current without compromising the voltage gain. Fabricated in a 0.18‐µm RF CMOS technology of Global Foundries, the mixer demonstrates a voltage gain of 15.8 dB and input‐referred third‐order intercept point of 6.6 dBm with a noise figure of 2.6 dB. It consumes 7.65 mA from a 1.0‐V supply and occupies a compact area of 0.75 × 0.71 mm² including all test pads. Copyright © 2016 John Wiley & Sons, Ltd.     

Design of triple‐band antenna using S‐shaped patch fed by cross strip line for WLAN and WiMAX applications

This paper presents a simple triple‐band S‐shaped patch antenna fed by a cross strip line for both WLAN and WiMAX applications. It is operated at the triple bands of 2.4 and 5.2 GHz for WLAN and 3.5 GHz for WiMAX. The antenna, designed on an FR4 substrate with a thickness of 1.6 mm and relative permittivity of 4.4, is fed by a 50‐Ω microstrip line, and is of size 25 × 35 mm. The simulated and measured results of |S₁₁|, gains, and radiation patterns are presented. The measured results show that the triple‐band antenna achieves a broad operating bandwidth of 2.36–2.54, 3.27–3.69, and 5.16–5.48 GHz for a 10‐dB return loss (i.e. |S₁₁|<−10 dB). The gains of the antenna measured at 2.4, 3.5, and 5.2 GHz frequencies are 1.87, 1.95, and 3.82, respectively. The radiation pattern of the antenna is omnidirectional. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Wireless power charger for wearable medical devices with in‐band communication

A wireless power charger integrated circuit has been developed for wearable medical devices in a 0.18‐µm Bipolar, Complementary metal‐oxide‐semiconductor, and Lightly‐Doped Metal‐Oxide‐Semiconductor (BCDMOS) process. A passive full‐wave rectifier consisting of Schottky diodes and cross‐coupled n‐type Metal‐Oxide‐Semiconductor (nMOS) transistors performs the alternating current to direct current power conversion without any reverse leakage current. To charge a battery, a linear charger circuit follows the passive rectifier instead of a switching charger circuit for the small form factor of wearable medical devices. An in‐band communication circuit notifies the proper connection of the wireless power receiver and the battery charging status to the charging pad (wireless power transmitter) through the wireless power transmission channel. The wireless power charger integrated circuit occupies 1.44‐mm² silicon area and shows 31.7% power efficiency when the charging current is 26.6 mA. Copyright © 2015 John Wiley & Sons, Ltd.     

Practical Application of ±250‐kV DC‐XLPE Cable for Hokkaido–Honshu HVDC Link

The long‐term dc properties of DC‐XLPE insulation materials, which have been developed for dc use, were investigated. It was found that the lifetime of DC‐XLPE under dc voltage application is extended by the addition of nano‐sized filler. The time dependence of the space charge distribution at 50 kV/mm was observed for 7 days. Almost no accumulation of space charge in DC‐XLPE was found. The 250‐kV DC‐XLPE cables and accessories were manufactured and subjected to a type test and PQ test for use in the Hokkaido–Honshu dc link facility owned by the Electric Power Development Co., Ltd. These tests were performed under conditions that included a polarity reversal test for line commutated converter (LCC) systems as recommended in CIGRE TB 219. The test temperature was 90 °C. The type test and PQ test were successfully completed. The DC‐XLPE cable and accessories were installed in summer 2012 for the Hokkaido–Honshu dc link. After the installation of the dc extruded cable system, a dc high‐voltage test at 362.5 kV (=1.45 PU) for 15 min was successfully completed in accordance with CIGRE TB 219. This dc extruded cable system was put into operation in December 2012 as the world's highest‐voltage extruded dc cable in service and the world's first dc extruded cable for a LCC system including polarity reversal operation.     

Development of 3‐in‐one high‐temperature superconducting cable

A three‐in‐one HTS cable has been developed. Its cable core is composed of a conductor and a shield wound with BSCCO and electrical insulation of the PPLP. The three cable cores are covered in thermal insulated stainless corrugated pipes. The BSCCO wires represent a dramatic innovation by virtue of a newly developed process named Controlled Over‐Pressure (CT‐OP). As a new cable technology, a 350‐m thermal insulation pipe was tested for 7 months to find that the life of the vacuum intensity is more than 10 years. The HTS cable with tension members was designed for installation into an underground duct. In addition, a fault current of 23 kA, 0.63 s, was applied to a sample cable with no damage to the BSCCO wires or the cable insulation. These technologies will be applied to the Albany project in the USA. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 15–24, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20577     

Power‐efficient burst‐mode RF transmitter based on reference‐adaptive multilevel pulse‐width modulation

Burst‐mode operation of power amplifier (PA) based on multilevel pulse‐width modulation (MPWM) has been frequently discussed as a potential solution to achieve higher efficiency in radio frequency (RF) transmitters. In this paper, a novel multilevel PWM modulator is proposed that utilizes adaptive triangular reference waveforms. As compared with conventional MPWM modulators, the proposed architecture provides significant wider design space such that the efficiency of system can be effectively optimized. A general transmitter architecture based on the proposed concept is analyzed in terms of power efficiency. Efficiency optimization procedures are presented according to input magnitude statistics. Based on the proposed modulator, an optimized 2.4‐GHz RF transmitter is designed in a 0.18‐μm complementary metal‐oxide‐semiconductor (CMOS) process. The circuit‐level simulations show that it delivers 25.8‐dBm peak output power with 46.1% peak efficiency. For a 20‐MHz worldwide interoperability for microwave access (WiMAX) signal with 8.5‐dB peak‐to‐average‐power ratio (PAPR), this transmitter achieves 28.8% (average) efficiency at 17.3‐dBm (average) output power with an error vector magnitude (EVM) of 2.97% rms.     

A 10 b 25 MS/s 4.8 mW 0.13 µm CMOS ADC with switched‐bias power‐reduction techniques

This paper proposes a 10 b 25 MS/s 4.8 mW 0.13 µm CMOS analog‐to‐digital converter (ADC) for high‐performance portable wireless communication systems, such as digital video broadcasting, digital audio broadcasting, and digital multimedia broadcasting (DMB) systems, simultaneously requiring a low‐voltage, low‐power, and small chip area. A two‐stage pipeline architecture optimizes the overall chip area and power dissipation of the proposed ADC at the target resolution and sampling rate, while switched‐bias power‐reduction techniques reduce the power consumption of the power‐hungry analog amplifiers. Low‐noise reference currents and voltages are implemented on chip with optional off‐chip voltage references for low‐power system‐on‐a‐chip applications. An optional down‐sampling clock signal selects a sampling rate of 25 or 10 MS/s depending on applications in order to further reduce the power dissipation. The prototype ADC fabricated in a 0.13 µm 1P8M CMOS technology demonstrates a measured peak differential non‐linearity and integral non‐linearity within 0.42 LSB and 0.91 LSB and shows a maximum signal‐to‐noise‐and‐distortion ratio and spurious‐free dynamic range of 56 and 65 dB at all sampling frequencies up to 25 MHz, respectively. The ADC with an active die area of 0.8 mm² consumes 4.8 and 2.4 mW at 25 and 10 MS/s, respectively, with a 1.2 V supply. Copyright © 2008 John Wiley & Sons, Ltd.     

A 3.6‐mW 6‐GHz current‐reuse VCO‐buffer with improved load drivability in 65‐nm CMOS

A new current‐reuse voltage‐controlled oscillator (VCO)‐buffer with enhanced load drivability is proposed. It incorporates a PMOS‐based source follower stacked atop a NMOS‐based LC VCO to share the bias current, while preventing the voltage stress at any oscillation node from exceeding the 1.2‐V technology voltage limit. Also, ac‐coupling networks are avoided between the VCO and buffer, improving the Q of the LC tank while minimizing parasitics. With internal buffering, the VCO can directly drive up a 50‐Ω load for testing, or to withstand a large capacitive load in on‐chip local oscillator distribution, particularly suitable for multi‐band MIMO WLAN radios . The fabricated VCO‐buffer in 65‐nm CMOS measures 13.8% tuning range from 5.64 to 6.4 GHz, consumes 3.6 mW at 1.2 V and exhibits ?108.84 dBc/Hz phase noise at 1‐MHz offset. Copyright © 2013 John Wiley & Sons, Ltd.