Abstract:
Methods and systems for secure communication include assigning data streams to respective orthogonal sub-carriers according to random number information at a transmitter. The data streams are modulated onto the respective orthogonal sub-carriers before the orthogonal sub-carriers are transmitted. The random number information is transmitted on a second medium, separate from the transmission medium. The orthogonal sub-carriers are received from the transmission medium at a receiver, while the random number information is received from the second medium at the receiver. The orthogonal sub-carriers are associated with data streams using the random number information and demodulated to produce data for the associated data stream.
Abstract:
Methods and devices for compensating for chromatic dispersion are shown that include receiving an input data signal, applying a filter to the data signal, and outputting a CD compensated signal. Applying the filter includes convolving known filter coefficients with a plurality of delayed versions of the data signal using addition and at least one inverse sign operation or using lookup tables and combining outputs to produce a CD compensated signal.
Abstract:
Systems and methods are disclosed for providing media access control (MAC) in an optical network by providing a separate control channel and data channel; dedicating each optical network unit (ONU) with one control channel, wherein the control message is transmitted at any time without constraints; sending a grant message to an ONU just before an allocated time is about to start; and sending data traffic from the ONU immediately after receiving the grant message without synchronizing with an optical line terminal (OLT) clock.
Abstract:
A method by an optical OFDM receiver includes converting a received optical signal to an electrical signal, deriving a digital signal from the electrical signal, and emulating, with an iterative OFDM demodulator responsive to the digital signal, a transmitter effect in the received signal of lower peak clipping and top peak distortion and applying the transmitter effect to the received signal and a decision-made signal for estimating an error function to be applied to a demodulation of the received optical signal.
Abstract:
A coded multidimensional modulation system called generalized OFDM (GOFDM) uses orthogonal subcarriers as bases functions, and the signal constellation points of corresponding multidimensional constellation diagram are obtained as N-dimensional Cartesian product of one-dimensional PAM/two-dimensional QAM. In GOFDM, the N-dimensional/2N-dimensional signal constellation point is transmitted over all N subcarriers/2N-subcarriers, which serve as individual bases functions. Even if some of the subcarriers are severely affected by channel distortion, the overall signal constellation point will face only small distortion, when strong channel capacity achieving channel codes are used. In addition, because the channel capacity is a linear function of number of dimensions, the spectral efficiency of optical transmission systems is significantly improved. Finally, since Euclidean distance of multidimensional signal constellation is much larger that that of two-dimensional signal constellations, OSNR sensitivity is dramatically improved.
Abstract:
A method for joint transmitter and receiver processing for computationally efficient equalization in polarization multiplexed (POLMUX) optical orthogonal frequency division multiplexed (OFDM) transmission with direct detection.
Abstract:
An optical receiver system is disclosed. The system includes a local oscillator, a mixer and a processor. The local oscillator is configured to generate a laser signal to indicate a selection of one of a plurality of channels. In addition, the mixer is configured to receive signals on the plurality of channels and to utilize the laser signal to distinguish the signal on the selected channel. Further, the processor is configured to maximize a power level difference between the laser signal and at least one of the plurality of channels based on a total number of the plurality of channels by adjusting the power of the laser signal input to the mixer to limit a noise penalty in the receiver system.
Abstract:
A method of producing an elastomer composite. The method includes A) combining a first fluid comprising elastomer latex with a second fluid comprising particulate filler; B) causing the elastomer latex to coagulate, thereby forming masterbatch crumb; C) bringing the masterbatch crumb to a water content of about 1 weight percent to about 20 weight percent, thereby forming a dewatered coagulum; D) removing water from the dewatered coagulum by subjecting the dewatered coagulum to mechanical energy, thereby causing the dewatered coagulum to heat as a result of friction, while allowing the dewatered coagulum to achieve a temperature of about 130° C. to about 190° C., wherein water content is reduced to about 0.5% to about 3% and wherein substantially all of the decrease in water content is accomplished by evaporation, thereby producing a masticated masterbatch; and E) subjecting the masticated masterbatch to at least an additional 0.3 MJ/kg of mechanical energy while further reducing the water content.
Abstract:
Methods and systems for receiving an optical signal using cascaded frequency offset estimation. Coherently detecting an optical signal includes compensating for a coarse laser frequency offset between a transmitting laser and a local oscillator laser by determining a maximum phase error (MPE) in the optical signal, compensating for a residual laser frequency offset between the transmitting laser and the local oscillator laser, and decoding data stored in the optical signal.
Abstract:
The utility model provides an apparatus for correcting upwarp deformation of a large member (11) of a stainless steel car roof, being characterized in that, comprising a crossbeam (1), end support columns (2), a middle support column (3), an arc-shaped positioning body (5), crossbeam pull rings (7), a thin steel taut strap (8), and tighteners (9), the end support columns (2), the crossbeam (1), and the middle support column (3) constitute a supporting part, the arc-shaped positioning body having the same arc shape as an inner arc of the large member of the stainless steel car roof is arranged on the middle support column (3), the thin steel taut strap (8) covers an exterior contour surface of the large member (11) of the stainless steel car roof, and is connected via the tightener (9) to the crossbeam pull rings (7) respectively fixed at two ends of the crossbeam (1). The apparatus can solve the problem of upwarp deformation of the large member of the stainless steel car roof, and restore the arc shape of the car roof and the car width.