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Modulation Scheme (modulation + scheme)

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Engineering	100%

Selected Abstracts

Adaptive coding and modulation scheme for satellite-UMTS TDD systems based on a photogrammetric channel estimation method

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 1 2006
Hsin-Piao Lin
Abstract The conventional wireless communication systems are designed to overcome the worst-case channel, using the huge amount of redundant bits to assure communications performance and quality of services. Those systems cannot achieve the optimum spectrum and power efficiency. This paper presents an adaptive coding and modulation scheme used in the user terminals of the third-generation satellite communication system. A three-state photogrammetric channel estimation method is introduced for tracing the variations of large-scale environments. The mobile user terminal dynamically switches the suitable coding and modulation schemes according to the result of photogrammetric channel estimator in order to maximize the power efficiency and data throughput. The real measurement data were used to validate our proposed method. The results show that the proposed method not only reduces the system complexity, but also mitigates the power control requirements and increases the data throughput for the land mobile satellite personal communication systems. Copyright © 2006 John Wiley & Sons, Ltd. [source]

Improvement of optical beam-forming networks based on broadband optical source and chirped fiber grating

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 11 2008
Bo Zhou
Abstract We propose a photonic beam-forming network scheme based on a broadband optical source (BS), double sideband suppressed carrier (DSB-SC) modulation, and a chirped fiber grating (CFG). The principle and feasibility are proved by both theoretical analysis and experiments. In 20,32 GHz microwave band, experimental results show a good delay time consistency and the ratio of RF signal to noise met the practical application demands. The time consistency errors are smaller than 3 ps in 20,40GHz band. Specially, compared with traditional double sideband (DSB) modulation scheme, in the proposed approach the dispersion-induced RF power degradation is effectively mitigated over 24 dB at 30 GHz, and the experimental results agree well with the theoretical ones. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2992,2994, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23802 [source]

To extend delivery distance of the optical MM-wave generated by DSB modulation and vestigial sideband filtering

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2006
Jianguo Yu
Abstract Due to RF fading effect caused by fiber dispersion in standard single-mode fiber (SSMF), the maximum delivery distance in SSMF for the optical millimeter (mm)-wave signals generated by the double-sideband modulation scheme is shorter than 2 km at a power penalty of 2 dB. We experimentally demonstrate that the maximum transmission distance can be largely extended after using vestigial sideband (VSB) filtering. When we use VSB filtering technique, the transmission distance for the mm-wave signals is extended more than 40 km at a power penalty of 2 dB. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1003,1004, 2006; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.21548 [source]