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With the rapid development of wireless communications technologies, radio spectrum has become a type of extremely scarce resources in meeting the increasing demands for broadband wireless services. However, the traditional static spectrum allocation policy leads to severe spectrum underutilization and spectrum shortage problems. The cognitive radio (CR)(More)
In wireless <i>ad-hoc</i> networks, network coding can take advantage of the bi-directional traffic flows to increase the achievable throughput. In this letter, on the one hand, cooperative diversity based on distributed cyclic delay diversity is integrated into the physical network coding scheme to combat fading in wireless channel. On the other hand, to(More)
The aim of this study was to define the genotypes of UGT1A1 and ERCC1 and to examine their relationship with the efficacy and toxicity of a combination therapy of irinotecan and cisplatin in patients with advanced ovarian cancer. The allelic frequencies of the UGT1A1 and ERCC1 variants in a group of 89 patients with advanced ovarian cancer were determined.(More)
OBJECTIVE To study the chemical constituents in the root of Isatis indigotica. METHOD The constituents root were separated through various chromatographic techniques and their structures were elucidated by means of physicochemical properties and the analysis of their spectral data. RESULT Eleven compounds were isolated and identified as (+)(More)
We propose and experimentally demonstrate the generation of a 10-Gb/s return-to-zero differential phase-shift keying (RZ-DPSK) signal based on a directly modulated chirp-managed laser (CML), without requiring any differential encoder and optical phase modulator (PM). It shows better fiber chromatic dispersion tolerance and comparable nonlinearity tolerance,(More)
We propose a novel scheme to suppress Rayleigh noise in carrier-distributed wavelength-division-multiplexed passive optical networks, by using differential phase-shift keying (DPSK) as the upstream modulation format. Due to the narrow spectrum of the distributed carrier, the Rayleigh noise towards the optical line terminal (OLT) also has narrow spectrum and(More)
To circumvent the challenging issue of Rayleigh noise reduction in wavelength-division-multiplexed passive optical network (WDM-PON), we provide an insight into the source of Rayleigh noise, and confirm that the suppression of carrier Rayleigh backscattering (RB) should be the primary target in the design of Rayleigh noise-resilient upstream receiver module(More)
Center launching is a simple and straightforward method to couple optical signals to a multimode fiber (MMF), and able to preferentially excite a few lower-order modes with reduced modal dispersion. However, system imperfections and mechanical perturbations will excite undesired higher order modes, leading to a selectively faded channel frequency response.(More)