A 60-GHz point-to-multipoint millimeter-wave fiber-radio communication system

A 60-GHz point-to-multipoint wireless access link with data rate of 156 Mb/s incorporating 60-GHz transceiver modules and full-duplex fiber-optic millimeter-wave transmission is developed for short-range applications such as indoor wireless local area networks and intelligent transport systems. For compact system configuration, a small-size millimeter-wave transceiver module with planar antennas is developed. The transceiver module is based on broadband planar integration and packaging of millimeter-wave circuits. The RF output power is +10 dBm and the measured 3-dB antenna beamwidth is 30/spl deg/. The total size of the developed 60-GHz transceiver module, except input and output connectors, is 50 mm /spl times/ 75 mm /spl times/ 35 mm. A point-to-point full duplex fiber-optic configuration is extended to the scheme with multiple access points (APs) by using a tree coupler and a dense wavelength division multiplexing multiplexer. The AP has a simple configuration without frequency conversion. The bit error rate and packet error rate performances of the 60-GHz fiber-radio access link are evaluated. Furthermore, the effect of the extension to the scheme with multiple APs is investigated.     

60 GHz band 64 QAM/OFDM terrestrial digital broadcasting signaltransmission by using millimeter-wave self-heterodyne system

This paper describes the first time experimental studies on 60-GHz band transmissions of terrestrial digital broadcasting signals (ISDB-T) with 64-QAM modulations on coded orthogonal frequency division multiplexing (COFDM) format. It has been a very difficult experiment to accomplish because it requires very stable and low phase-noise oscillators in the millimeter-wave band. The use of our proposed millimeter-wave self-heterodyne system, overcame this problem without using a stable oscillator, and provided a bit error rate (BER) of less than 10^-6 without any forward error correction. We also discuss the relationship between the carrier-to-noise power ratio and the BER obtained, and demonstrate that the penalty of the required CNR for our experimental system is less than 1 dB compared to the results of a back-to-back BER test     

10-Gb/s millimeter-wave signal generation using photodiode bias modulation

We present a simple 120-GHz-band millimeter-wave (MMW) modulation method that uses the bias-voltage dependence of unitraveling-carrier-photodiode output power, which we call photodiode (PD) bias modulation. We investigated the dependence of the output-power-saturation mechanisms on the bias voltage. We used a lowpass filter in the bias circuit to increase the modulation bandwidth, and the 3-dB modulation bandwidth was over 7 GHz. We demonstrated the modulation of 120-GHz MMW signals at a data rate of 10 Gb/s using PD bias modulation.     

采用PM调制实现光生毫米波的RoF系统

提出有效产生四倍频光载毫米波的RoF系统.系统在中心站配置一个PM调制器和光滤波器,产生抑制一阶边带和中心载波的信号,发送至基站.基站侧两个二阶边带在光电检测器中拍频,产生四倍于射频信号的光载毫米波.仿真结果显示,12GHz射频频率可产生48GHz光载毫米波,2.5Gb/s的数据可在下行链路的光纤中传输35km以上,功...     

60 GHz millimeter-wave source using two-mode injection-locking of aFabry-Perot slave laser

We demonstrate 60 GHz carrier generation and transmission using a two-mode injection-locked Fabry-Perot (F-P) slave laser. The relationship between the power of the generated carriers and the frequency of the reference signal for the injection-locking is also investigated. The RF power-penalty caused by fiber dispersion was within 2.0 dB when the locked modes were transmitted at a distance of 0.5-48 km. Accordingly, the two-mode locked F-P laser can be used in fiber-based millimeter-wave systems     

Reciprocating optical modulation for millimeter-wave generation by using a dual-section fiber Bragg grating

We investigated reciprocating optical modulation (ROM) for millimeter-wave generation. The system was composed of an optical phase modulator and a pair of optical filters. A lightwave modulated by V-band millimeter waves was obtained from a 5-GHz electric signal. The spectrum linewidths of the generated 60-GHz millimeter wave was smaller than 300 Hz. By using mode-coupling equations, the spectra of the output lightwave were theoretically calculated. It was shown that the spectra depend on the optical path length between the two optical filters, so that harmonic generation and mixing with baseband signals can be obtained simultaneously. Intensity modulation of the generated millimeter wave was demonstrated by applying a baseband signal to the modulator without using another electric or optical modulator.     

LTE系统下行链路的一种AMC方案

高速数据和多媒体业务对新一代移动通信系统提出了更高的要求,自适应调制与编码（AMC）因其在提高频谱效率方面的显著特点,成为3GPP长期演进（LTE）系统的一项关键技术。本文基于LTE系统物理层下行链路模型,分析了在LTE系统中AMC与混合自动重传（HARQ）技术的主要特点,提出一种针对LTE下行链路的AMC方案,并对该方案在模型下的性能进行了讨论。仿{真结果表明,采用AMC技术对提升LTE系统容量作用显著。     

光纤图像精确制导系统

光纤制导是正处于蓬勃发展中的精确制导技术,它抗干扰能力强、制导精度高,具有超视距精确打击能力。介绍了光纤图像制导系统的技术特点和基本原理,讨论了光纤图像制导的关键技术,如图像导引头、光纤双向传输系统、图像跟踪器等,给出了光纤制导系统应用的实例及试验结果,分析了其应用方向和发展前景。     

Channel state-aware joint dynamic cell coordination scheme using adaptive modulation and variable reuse factor in OFDMA downlink

This paper proposes three different dynamic cell coordination schemes using adaptive link adaptation and variable frequency reuse for OFDMA downlink cellular networks, which are composed of greedy cell coordination for flat fading channel, dynamic maximum C/I cell coordination (DMCC), and dynamic proportional fairness cell coordination (DPFCC) for frequency selective fading channel. The performances of the proposed dynamic cell coordination schemes are compared to those with no cell coordination schemes and static reuse coordination schemes using conventional proportional fair (PF) scheduling in terms of system throughput and fairness. Simulation results demonstrate that the proposed schemes allow the radio network controller (RNC) and base stations (BSs) to apply different reuse factors on each subchannel in consideration of different interference conditions of individual users so as to increase the system throughput and guarantee QoS requirement of each user on the multicell environment, where the performance of conventional OFDMA downlinks might have become degraded due to persistent interference from other cells. In frequency flat fading, the proposed dynamic schemes achieve, on average, a 1.2 times greater system throughput than no cell coordination, a 1.4 times greater static cell coordination and a 3 times greater simplified subchannel allocation scheme (SSAS) (Kim et al. in Proceedings of IEEE VTC spring’04, vol. 3, pp. 1821–1825, 2004). In frequency selective fading, the proposed scheme, DMCC, showed a 2.6 times greater throughput than that of a single reuse factor of one for all subcarriers, and DPFCC demonstrated a single reuse factor as good as one.     

120-GHz wireless link using photonic techniques for generation, modulation, and emission of millimeter-wave signals

We present a wireless link system that uses millimeter-wave (MMW) photonic techniques. The photonic transmitter in the wireless link consists of an optical 120-GHz MMW generator, an optical modulator, and a high-power photonic MMW emitter. A uni-traveling carrier photodiode (UTC-PD) was used as the photonic emitter in order to eliminate electronic MMW amplifiers. We evaluated the dependence of UTC-PD output power on its transit-time limited bandwidth and its CR-time constant limited bandwidth, and employed a UTC-PD with the highest output power for the photonic emitter. As for the MMW generation, we developed a 120-GHz optical MMW generator that generates a pulse train and one that generates a sinusoidal signal. The UTC-PD output power generated by a narrow pulse train was higher than that generated by sinusoidal signals under the same average optical power condition, which contributes to reducing the photocurrent of the photonic emitter. We have experimentally demonstrated that the photonic transmitter can transmit data at up to 3.0 Gb/s. The wireless link using the photonic transmitter can be applied to optical gigabit Ethernet signals.     

Fiber-optic digital video distribution system for usinghigh-definition television signals using laser-diode optical switch

A fiber-optic high-definition television (HDTV) distribution system is discussed, which economically distributes HDTV signals to customers at a bit rate of about 100 Mb/s. The subscriber network is formed in a star topology to facilitate bidirectional connection. The distribution system uses digital video transmission at 1.3 μm wavelength using single-mode fiber. The video channel selection is made by an optical video selector. The optical selector consists of laser diode optical switch modules, which have a gain in the `ON' state and two-input, two-output 3 dB couplers. The authors describe the bit error rate characteristics of a signal-mode fiber digital distribution system using a four-input, one-output optical selector     

An active tagging system using circular-polarization modulation

An active read/write microwave tagging system using circular-polarization modulation as a novel modulation scheme for radio-frequency identification systems is presented. The proposed modulation scheme reduces demodulation complexity and power consumption on the battery-powered tag. Additional coding of the circular-polarization modulated data reduces transmission errors due to polarization inversion at multipath propagation. In multiple-reader environments, the main jamming threat occurs from power carriers of different interrogators. A combination of circular-polarization modulation and frequency hopping is presented that shows an increased immunity against multipath phenomena for multiple-tag and multiple-reader environments     

Fiber-optic digital video multiplexing using optical CDMA

The use of laser pulsing in the form of code-division multiple access (CDMA) to multiplex a set of digital video signals over a fiber network is proposed. The laser pulsing is used to generate unique code sequence addresses which identify each source, and the video data are modulated on these sequences. Digital encoding using pulse position modulation (PPM) is proposed, having advantages that permit efficient integration of optical and electronic processing. Data recovery is achieved by optical correlation for sequence recognition, followed by standard electronic PPM decoding. The relation between key system parameters of the encoding, decoding, and optics is derived, and indicates that compressed video rates between 5 and 20 Mb/s/channel, with 25-50 channels, is possible with relatively standard hardware. Experimental breadboard results being carried out at USC on this system indicate the feasibility of the CDMA concept for fiber multiplexing     

Fiber-optic sensor using an injection-locked local laser

An interferometric fiber-optic sensor using a local laser is proposed. An Er-doped-fiber ring-laser is injection locked to a signal carrier using a fiber coupler, and the extracted carrier is directly homodyned with the signal light at the output of the coupler. With a feedback loop suppressing the local laser instability, demodulation linearity over two decades and minimum detection in the 10^-3 rad range are attained. The Er-doped fiber ring laser constructed for this work has a linewidth of less than 1.4 kHz. Acceptable signal frequency ranges and the linearity and sensitivity of the proposed sensor are examined. Also discussed is the applicability of this configuration to simple, long-spanned sensors     

A millimeter-wave six-port reflectometer using dielectric waveguide

A six-port reflectometer circuit that is particularly suited to dielectric-type waveguides is described. Its scattering matrix is derived, allowing for flexibility in design. A phase-shifting network is incorporated in the circuit, and it is shown that a quadrature hybrid can be configured for this purpose. The reflectometer was implemented in a dielectric waveguide for W-band (75 GHz-110 GHz) operation, and measurements are presented     

A displacement measurement technique using millimeter-wave interferometry

A displacement measurement sensor, capable of sub-millimeter resolution, using millimeter-wave interferometry has been developed. The sensor operates at 37.6 GHz and is realized using both microwave integrated circuits and monolithic microwave integrated circuits. It has been used to accurately measure the displacement of metal plate location and water level. A resolution of only 0.05 mm is achieved. A maximum error of 0.3 mm is also attained without correction for the nonlinearity of the phase-detection processor and agrees well with the theoretical calculation.     

Multi-state chaos-shift-keying modulation system using feedbacksynchronising Chua's circuit

A new type of chaos-shift-keying (CSK) modulation, called multi-state CSK, is presented for the first time. In a classical CSK communication system, using this type of modulation combined with feedback synchronisation, the data rate can be greatly increased. Laboratory test results conform very well with theoretical analysis     

EDGE系统及其下行无线链路预算的研究

EDGE作为GPRS的增强型演进技术,可作为第二代移动网络向第三代移动网络的过渡方案。从技术特点和物理信道两个方面把EDGE系统与GPRS系统进行了比较,同时对EDGE系统的下行无线链路预算进行了详细地分析,得出在不同信噪比和信号强度下,EDGE系统下行链路的最大允许路径损耗、覆盖半径和实际的下行速率。     

60-GHz-band full-duplex radio-on-fiber system using two-RF-portelectroabsorption transceiver

A full-duplex radio-on-fiber system using a newly developed 60-GHz-band optical transceiver is investigated. We fabricated a 60-GHz-band two-radio-frequency (RF)-port electroabsorption transceiver (EAT) module, which is the first developed 60-GHz-band optical transceiver in the world. The EAT module has individual RF input and output ports, each with impedance-matching circuits that enhance modulation and detection efficiencies near 60 GHz. A radio-on-fiber testbed adopting the EAT has an advantage that a base station becomes the simplest configuration, which basically consists of only the 60-GHz-band EAT. Using the radio-on-fiber testbed, the simultaneous transmission of 59.6-GHz (downlink) and 60.0-GHz (uplink) signals with data of 156 Mb/s is experimentally demonstrated     

Fiber-optic reflection measurements using OCWR and OTDR techniques

A method for determining the backscatter and reflection responses of an optical fiber and reflector to an arbitrary input is developed. Two cases are specifically considered: a continuous-wave input and a rectangular pulse input. From the rectangular pulse input response, the equation is derived for computing the reflectance of a discrete component from an optical time-domain reflectometer (OTDR) measurement. Precautions are given for accurately performing reflectance measurements using an OTDR. Two methods are presented for determining the backscatter level of the fiber type under test, and its importance in reflection measurements is shown