Time filter

Source Type

Fonseka J.P.,University of Texas at Dallas | Dowling E.M.,Trellis Phase Communications LP
IEEE Communications Letters | Year: 2011

Compact pulse shaping (CPS) is considered with PAM/QAM signals to improve the performance/bandwidth tradeoff. CPS signals are constructed by targeting a finite impulse response of a pulse shaping filter as opposed to the traditional method of targeting a finite frequency response. CPS QAM signals can be optimally decoded using Viterbi decoding on I and Q channels independently. In the case of non-rectangular constellations, a simple adjustment is presented to correct any invalid QAM symbols that result from independent I and Q decoding. Minimum distance calculations indicate that CPS QAM provides between 2.04 and 5.4 dB of gain, depending on constellation size, over raised cosine filtering, when compared at a given value of the normalized bit bandwidth B 99Tb. © 2011 IEEE.


Han S.I.,University of Texas at Dallas | Fonseka J.P.,University of Texas at Dallas | Dowling E.M.,Trellis Phase Communications LP
IEEE Photonics Technology Letters | Year: 2014

Constrained turbo block convolutional (CTBC) codes are developed for 100 G and beyond optical transmissions. The CTBC codes developed herein each fit within one optical transport network (OTN) frame. The CTBC codes involve a simple outer block code that is serially concatenated with a simple inner recursive convolutional code using a constrained interleaver that simultaneously delivers a high interleaver gain and a high minimum Hamming distance. Codes with 11.1 dB net coding gain (NCG) at 12.5% overhead (OH), 11.3 dB NCG at 15% OH, 11.6 dB NCG at 20% OH, and 11.9 dB NCG at 23.4% OH are reported. Compared with other codes that have been previously proposed for OTN applications, CTBC codes have much lower encoding/decoding complexity, improved NCG/OH tradeoffs, and avoid negative error floor effects. © 1989-2012 IEEE.

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