15 MHz channel spacing of two frequency division multiplexed optical carriers intensity-modulated with analogue video signals

1988 ◽  
Vol 24 (9) ◽  
pp. 526
Author(s):  
S.M. Stone
Keyword(s):  
Frequency Division ◽  
Channel Spacing ◽  
Video Signals ◽  
Intensity Modulated

scholarly journals LDPC-Coded Generalized Frequency Division Multiplexing for Intensity-Modulated Direct-Detection Optical Systems

2019 ◽  
Vol 11 (2) ◽  
pp. 1-15
Author(s):  
Dong Guo ◽  
Wei Zhang ◽  
Feng Tian ◽  
Jianyang Shi ◽  
Kaihui Wang ◽  
...  
Keyword(s):  
Direct Detection ◽  
Optical Systems ◽  
Frequency Division Multiplexing ◽  
Frequency Division ◽  
Intensity Modulated

Demonstration of channel-spacing-tunable demultiplexing of optical orthogonal-frequency-division-multiplexed subcarriers utilizing reconfigurable all-optical discrete Fourier transform

2012 ◽  
Vol 37 (19) ◽  
pp. 3975 ◽  
Author(s):  
Mohammad Reza Chitgarha ◽  
Salman Khaleghi ◽  
Omer F. Yilmaz ◽  
Moshe Tur ◽  
Michael W. Haney ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Discrete Fourier Transform ◽  
Frequency Division ◽  
Channel Spacing ◽  
All Optical

Performance Analysis of Hybrid PON (WDM-TDM) with Equal and Unequal Channel Spacing

2016 ◽  
Vol 37 (2) ◽  
Author(s):  
Ramandeep Sharma ◽  
Sanjeev Dewra ◽  
Aruna Rani
Keyword(s):  
Performance Analysis ◽  
Optical Network ◽  
Q Factor ◽  
Channel Spacing ◽  
Video Signals ◽  
Triple Play ◽  
Triple Play Services

AbstractIn this hybrid WDM-TDM PON has been evaluated and compared the downstream wavelengths with equal and unequal channel spacing at 5 Gbit/s per wavelength in the scenario of triple play services with 128 optical network units (ONUs). The triple play services: data, voice and video signals are transmitted up to 50 km distance having Q factor of 6.68 and BER of 3.64e-012 with unequal channel spacing and 45 km distance having Q factor of 6.33 and BER of 2.40e-011 with equal channel spacing in downstream direction. It has been observed that downstream wavelengths with unequal channel spacing provide better results than equal channel spacing.

Study of Power Control in CDMA System on the basis of optimization Technique

2017 ◽  
Vol 7 (8) ◽  
pp. 126
Author(s):  
. Geetanjli
Keyword(s):  
Power Control ◽  
Multiple Access ◽  
Optimization Technique ◽  
System Optimization ◽  
Base Station ◽  
Particle Swarm Algorithm ◽  
Cdma System ◽  
Frequency Division ◽  
Cdma Systems ◽  
Time Division

The power control in CDMA systems, grant numerous users to share resources of the system uniformly between each other, leading to expand capacity. With convenient power control, capacity of CDMA system is immense in contrast of frequency division multiple access (FDMA) and time division multiple access (TDMA). If power control is not achieved numerous problems such as the near-far effect will start to monopolize and consequently will reduce the capacity of the CDMA system. However, when the power control in CDMA systems is implemented, it allows numerous users to share resources of the system uniformly between themselves, leading to increased capacity For power control in CDMA system optimization algorithms i.e. genetic algorithm & particle swarm algorithm can be used which regulate a convenient power vector. These power vector or power levels are dogged at the base station and announce to mobile units to alter their transmitting power in accordance to these levels. The performances of the algorithms are inspected through both analysis and computer simulations, and compared with well-known algorithms from the literature.

Helical tomotherapy for advanced esophageal cancer improves target conformity and homogeneity: A comparison with fixed-field intensity-modulated radiotherapy

2015 ◽  
Vol 11 (3) ◽  
pp. 3146-3155
Author(s):  
Luhua Wang
Keyword(s):  
Esophageal Cancer ◽  
Field Intensity ◽  
Helical Tomotherapy ◽  
Intensity Modulated Radiotherapy ◽  
Matched Pair ◽  
Conformity Index ◽  
Target Coverage ◽  
Advanced Esophageal Cancer ◽  
Fixed Field ◽  
Intensity Modulated

Purpose: To evaluate the usefulness of helical tomotherapy (HT) in the treatment of advanced esophageal cancer (EC) and compare target homogeneity, conformity and normal tissue doses between HT and fixed-field intensity-modulated radiotherapy (ff-IMRT).Methods: In all, 23 patients with cT3-4N0-1M0-1a thoracic EC (upper esophagus, 9 patients; middle esophagus, 6; distal esophagus, 6 and esophagogastric junction, 2) who were treated with ff-IMRT (60 Gy in 30 fractions) were re-planned for HT and ff-IMRT with the same clinical require­ments. Comparisons were performed using the Wilcoxon matched-pair signed-rank test.Results: Compared with ff-IMRT, HT significantly reduced the homogeneity index for thoracic, upper, middle and distal ECs by 38%, 31%, 36% and 33%, respectively (P < 0.05). The conformity index was increased by HT for thoracic, upper and middle ECs by 9%, 9% and 18%, respectively (P < 0.05). Target coverage was improved by 1% with HT (P < 0.05). The mean lung dose was significantly reduced by HT for thoracic and upper ECs (P < 0.05). The V20 (volume receiving at least 20 Gy) and higher dose volumes of the lungs were decreased by HT in all cases, but the differences were significant for thoracic, upper and distal ECs (P < 0.05), with reductions of 2.1%, 3.1% and 2.2%, respectively. HT resulted in a larger lung V5 for thoracic, upper, middle and distal ECs, with increases of 3.5%, 1.5%, 7.2% and 3.2%, respectively. Heart sparing was significantly better with HT than with ff-IMRT in terms of the V30 and V40 for thoracic, upper, middle and distal ECs (P < 0.05).Conclusions: Compared to ff-IMRT, HT provides superior target coverage, conformity and homogeneity, with reduced the volume of high doses to the lungs and heart for advanced EC. HT may be a treatment option for advanced EC, especially upper EC.

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