In the bit-interleaved coded modulation with iterative decoding,it is desired that any two Hamming neighbors,i.e..signal constellation points whose binary labels are at unit Hamming distance,be separated by a large Eu...In the bit-interleaved coded modulation with iterative decoding,it is desired that any two Hamming neighbors,i.e..signal constellation points whose binary labels are at unit Hamming distance,be separated by a large Euclidean distance.This paper determines the mappings for the 32-ary fourdimensional generalized cross constellation（32-4D-GCC） so that the minimum squared Euclidean distance d_（min）~2 between Hamming neighbors is maximized.Among such mappings,those with minimum multiplicity N（d_（min）~2） are selected.To reduce the large search space,a set of ＂mapping templates,＂ each producing a collection of mappings with the same set partitions of binary labels,is introduced.Via enumeration of mapping templates,it is shown that the optimum d_（min）~2=16and the optimum N（d_（min）~2）=16.Among thousands optimum mappings found by computer search,two of the best performance are presented.展开更多
An offset quadrature amplitude modulation orthogonal frequency-division multiplexing(OQAM-OFDM) passive optical network(PON) architecture with direct detection is brought up to increase the transmission range and impr...An offset quadrature amplitude modulation orthogonal frequency-division multiplexing(OQAM-OFDM) passive optical network(PON) architecture with direct detection is brought up to increase the transmission range and improve the system performance.In optical line terminal(OLT),OQAM-OFDM signals at 40 Gbit/s are transmitted as downstream.At each optical network unit(ONU),the optical OQAM-OFDM signal is demodulated with direct detection.The results show that the transmission distance can exceed 20 km with negligible penalty under the experimental conditions.展开更多
With the help of self-similarity transformation, we construct and study the nonautonomous vortices with different topological charges inside a planar graded-index nonlinear waveguide, analytically, and numerically. Al...With the help of self-similarity transformation, we construct and study the nonautonomous vortices with different topological charges inside a planar graded-index nonlinear waveguide, analytically, and numerically. Although these vortices are approximate, they can reflect the real properties of self-similar optical beam during a short-term propagation. Existence of these autonomous vortices require delicate balances between the system parameters such as diffraction, nonlinearity, gain, and external potential. We are concerned with some special but interesting situations, and discussing the changes of the height, width, energy, and central position of the vortices as the increase of propagation distance. Moreover, we are also interested in the azimuthal modulational instability of the system, and comparing our prediction for the modulational instability growth rates to numerical results.展开更多
基金supported by the National Key Basic Research Program of China(973 program) under grant No.2010CB328206NSFC under grants No.60837002+3 种基金60807003and 61102048the Fundamental Research Funds for the Central Universities under grant No.2011JBM208NSF under grant CCF-0952711
文摘In the bit-interleaved coded modulation with iterative decoding,it is desired that any two Hamming neighbors,i.e..signal constellation points whose binary labels are at unit Hamming distance,be separated by a large Euclidean distance.This paper determines the mappings for the 32-ary fourdimensional generalized cross constellation（32-4D-GCC） so that the minimum squared Euclidean distance d_（min）~2 between Hamming neighbors is maximized.Among such mappings,those with minimum multiplicity N（d_（min）~2） are selected.To reduce the large search space,a set of ＂mapping templates,＂ each producing a collection of mappings with the same set partitions of binary labels,is introduced.Via enumeration of mapping templates,it is shown that the optimum d_（min）~2=16and the optimum N（d_（min）~2）=16.Among thousands optimum mappings found by computer search,two of the best performance are presented.
基金supported by the National Natural Science Foundation of China(No.61431009)the Natural Science Foundation of Shandong Province(No.ZR2014FL002)
文摘An offset quadrature amplitude modulation orthogonal frequency-division multiplexing(OQAM-OFDM) passive optical network(PON) architecture with direct detection is brought up to increase the transmission range and improve the system performance.In optical line terminal(OLT),OQAM-OFDM signals at 40 Gbit/s are transmitted as downstream.At each optical network unit(ONU),the optical OQAM-OFDM signal is demodulated with direct detection.The results show that the transmission distance can exceed 20 km with negligible penalty under the experimental conditions.
文摘With the help of self-similarity transformation, we construct and study the nonautonomous vortices with different topological charges inside a planar graded-index nonlinear waveguide, analytically, and numerically. Although these vortices are approximate, they can reflect the real properties of self-similar optical beam during a short-term propagation. Existence of these autonomous vortices require delicate balances between the system parameters such as diffraction, nonlinearity, gain, and external potential. We are concerned with some special but interesting situations, and discussing the changes of the height, width, energy, and central position of the vortices as the increase of propagation distance. Moreover, we are also interested in the azimuthal modulational instability of the system, and comparing our prediction for the modulational instability growth rates to numerical results.
