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Chen W.,Beijing Information Science and Technology University | Li W.,CAS Institute of Electronics | Zhang X.,State Key Laboratory of Information Photonics and Optical Communications
Journal of Theoretical and Applied Information Technology | Year: 2012

Aiming at the requirements of high-speed data transmission and low energy consumption in energy constrained Wireless Sensor Networks (WSNs), a mobile robot-based virtual V-BLAST cooperative MIMO transmission scheme and an efficient approximate maximum likelihood (ML) detection algorithm are proposed in this paper. Mobility of robot can reduce the communication distance between the sensor nodes, MIMO-based WSNs can use its diversity gain to overcome fading effects and can also use its multiplexing gain to increase the data transmission rate. As for the detection algorithm in mobile robot-based virtual V-BLAST transmission scheme, combined with traditional decoding OSIC algorithm, the vectors needed to be detected in approximate ML algorithm are reduced. Mobile robot can receive with its own multi-antenna or using collaborative nodes around, and the energy efficiency analysis of the two cases are all discussed. Simulation results show that the proposed scheme effectively reduces network energy consumption, and the efficient approximate ML detection algorithm further improves energy-efficiency. © 2005 - 2012 JATIT & LLS. All rights reserved. Source


Gao G.,State Key Laboratory of Information Photonics and Optical Communications | Gao G.,University of Melbourne | Chen X.,University of Melbourne | Shieh W.,University of Melbourne
Optics Express | Year: 2012

With ideal nonlinearity compensation using digital back propagation (DBP), the transmission performance of an optical fiber channel has been considered to be limited by nondeterministic nonlinear signal-ASE interaction. In this paper, we conduct theoretical and numerical study on nonlinearity compensation using DBP in the presence of polarization-mode dispersion (PMD). Analytical expressions of transmission performance with DBP are derived and substantiated by numerical simulations for polarization-division-multiplexed systems under the influence of PMD effects. We find that nondeterministic distributed PMD impairs the effectiveness of DBP-based nonlinearity compensation much more than nonlinear signal-ASE interaction, and is therefore the fundamental limitation to single-mode fiber channel capacity. © 2012 Optical Society of America. Source


Liang S.,State Key Laboratory of Information Photonics and Optical Communications | Chen X.,State Key Laboratory of Information Photonics and Optical Communications
Advances in Information Sciences and Service Sciences | Year: 2012

The avalanche photodiode (APD) based receiver sensitivity of synchronous electrical code division multiple access passive optical networks (ECDMA-PON) are theoretically analyzed and experimentally investigated. The en/decoding processing provide coding gain to improve sensitivity of ECDMA-PON comparing with traditional time division multiple access(TDMA)-PON. When the encoded chip rate and system capacity of ECDMA-PON is equal to that of TDMA-PON respectively, the theoretical results show that sensitivity improvement is proportional to code length which has been validated by the experimental 2.5Gchip/s demonstration. Source


Yang D.,State Key Laboratory of Information Photonics and Optical Communications | Yang D.,Beijing University of Posts and Telecommunications | Tian H.,State Key Laboratory of Information Photonics and Optical Communications | Tian H.,Beijing University of Posts and Telecommunications | And 2 more authors.
Optics Express | Year: 2011

We present nanoscale photonic crystal sensor arrays (NPhCSAs) on monolithic substrates. The NPhCSAs can be used as an opto-fluidic architecture for performing highly parallel, label-free detection of biochemical interactions in aqueous environments. The architecture consists of arrays of lattice-shifted resonant cavities side-coupled to a single PhC waveguide. Each resonant cavity has slightly different cavity spacing and is shown to independently shift its resonant peak (a single and narrow drop) in response to the changes in refractive index. The extinction ratio of welldefined single drop exceeds 20 dB. With three-dimensional finite-difference time-domain (3D-FDTD) technique, we demonstrate that the refractive index sensitivity of 115.60 nmRIU (refractive index unit) is achieved and a refractive index detection limit is approximately of 8.65 × 10∼5 for this device. In addition, the sensitivity can be adjusted from 84.39 nmRIU to 161.25 nmRIU by changing the number of functionalized holes. © 2011 Optical Society of America. Source


Shen G.,State Key Laboratory of Information Photonics and Optical Communications | Shen G.,Beijing University of Posts and Telecommunications | Tian H.,State Key Laboratory of Information Photonics and Optical Communications | Tian H.,Beijing University of Posts and Telecommunications | And 2 more authors.
Applied Optics | Year: 2013

We design two microwave photonic filters (notch filter and bandpass filter) based on silicon on insulator (SOI) photonic crystal waveguides for a 60 GHz single-sideband signal radio-over-fiber (ROF) system. By perturbing the radii of the first two rows of holes adjacent to the photonic crystal waveguide, we obtained a broad negligible dispersion bandwidth and a corresponding constant low group velocity. With the slow light effect, the delay line of filters can be significantly reduced while providing the same delay time as fiber based delay lines. The simulation results show that the delay-line length of the notch filter is only about 25.9 μm, and it has a free spectral range of 130 GHz, a baseband width (BW) of 4.12 GHz, and a notch depth of 22 dB. The length of the bandpass filter is 62.4 μm, with a 19.6 dB extinction ratio and a 4.02 GHz BW, and the signal-to-noise ratio requirement of received data can be reduced by 9 dB for the 10-7 bit-error ratio. Demonstrated microwave photonic crystal filters could be used in a future high-frequency millimeter ROF system. © 2013 Optical Society of America. Source

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