Optical Techniques for Up-Conversion of MB-OFDM Signals in 60 Ghz Band Using Fiber Bragg Grating
ABSTRACT We have demonstrated two techniques for all optical frequency up-conversion of Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) signal with 400 Mbps bit rate in the 60 GHz band. The first technique is based on direct modulation of Laser Diode (LD) associated with an electro-optic modulator (EOM) and the second one is based on two cascaded EOMs. For both techniques, a fiber Bragg grating (FBG) is inserted to suppress undesired signal around 60 GHz band. Direct modulation of LD with an EOM is cost effective compared to two cascaded EOMs, and exhibits a gain of 5 dB in the received optical power. A minimum error vector magnitude (EVM) of 18% and 20% are measured for direct modulation of LD with an EOM and two cascaded EOMs techniques, respectively which complies with MB-OFDM standard.
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ABSTRACT: In February 2002, the Federal Communications Commission allocated 7500 MHz of spectrum for unlicensed use of commercial ultra-wideband (UWB) communication devices. This spectral allocation has initiated an extremely productive activity for industry and academia. Wireless communications experts now consider UWB as available spectrum to be utilized with a variety of techniques, and not specifically related to the generation and detection of short RF pulses as in the past. There are many differences between real-world behavior of narrow-band and UWB systems. All wireless systems must be able to deal with the challenges of operating over a multipath propagation channel, where objects in the environment can cause multiple reflections to arrive at the receiver (RX). For narrow-band systems, these reflections will not be resolvable by the RX when the narrow-band system bandwidth is less than the coherence bandwidth of the channel. The large bandwidth of UWB waveforms, instead, significantly increases the ability of the RX to resolve the different reflections in the channel. The UWB channel model developed by the IEEE 802.15.3a standard body is described in this paper. For highly dispersive channels, an orthogonal frequency-division multiplexing (OFDM) RX is more efficient at capturing multipath energy than an equivalent single-carrier system using the same total bandwidth. OFDM systems possess additional desirable properties, such as high spectral efficiency, inherent resilience to narrow-band RF interference, and spectral flexibility, which is important because the regulatory rules for UWB devices have not been finalized throughout the entire world. This paper describes the design of a UWB system optimized for very high bit-rate, low-cost, and low-power wireless networks for personal computing (PC), consumer electronics (CE), and mobile applications. The system combines OFDM modulation technique with a multibanding approach, which divides the spectrum into several sub-bands, whose bandwidth is approximately 500 MHz. The system described in this paper has been selected by several key industry organizations [Mulitband OFDM Alliance, WiMedia, Wireless Universal Serial Bus (USB)] because of its very good technical characteristics for the diverse set of high performance- short-range applications that are eagerly anticipated for CE, PC, and mobile applications.IEEE Transactions on Microwave Theory and Techniques 10/2004; · 2.23 Impact Factor
Conference Proceeding: Technologies for UWB-Over-Fiber[show abstract] [hide abstract]
ABSTRACT: This paper investigates distribution and processing of ultrawideband signals for radio over fiber network. Architectures of single-mode and multimode systems are discussed to find a cost effective solution for UWB over fiber up and down-link systemsLasers and Electro-Optics Society, 2006. LEOS 2006. 19th Annual Meeting of the IEEE; 11/2006
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ABSTRACT: Efficient frequency conversion into and out of the millimeter wave frequency band has been demonstrated using photonic link signal mixing with cascaded optical modulators. By adjusting the modulator bias point and RF drive power to the modulator introducing the local oscillator signal at f/sub LO/=8.8 GHz, frequency conversions from f/sub s/ to f/sub LO//spl plusmn/f/sub s/, sf/sub LO//spl plusmn/f/sub s/, and 4f/sub LO//spl plusmn/f/sub s/ with respective losses of 4.8, 6.3, and 7.5 dB have been demonstrated. The direct phase noise measurement of the optical RF signal at 2f/sub LO/=17.6 GHz with 1 kHz offset shows -89 dBc/Hz, limited by the RF drive source.IEEE Photonics Technology Letters 10/1996; · 2.04 Impact Factor