Abstract: To allocate resources in an orthogonal frequency domain multiple access (OFDMA) system, two-dimensional rectangular regions are assigned in a frequency-time space to data bursts associated with mobile stations. At least one data burst does not fit in an available space in the frequency-time space is determined. In response to the determining, the assigned two-dimensional rectangular regions are reshaped.

Abstract: To allocate resources in an orthogonal frequency domain multiple access (OFDMA) system, two-dimensional rectangular regions are assigned in a frequency-time space to data bursts associated with mobile stations. At least one data burst does not fit in an available space in the frequency-time space is determined. In response to the determining, the assigned two-dimensional rectangular regions are reshaped.

Abstract: To allocate resources in an orthogonal frequency domain multiple access (OFDMA) system, two-dimensional rectangular regions are assigned in a frequency-time space to data bursts associated with mobile stations. At least one data burst does not fit in an available space in the frequency-time space is determined. In response to the determining, the assigned two-dimensional rectangular regions are reshaped.

Abstract: To allocate resources in an orthogonal frequency domain multiple access (OFDMA) system, two-dimensional rectangular regions are assigned in a frequency-time space to data bursts associated with mobile stations. At least one data burst does not fit in an available space in the frequency-time space is determined. In response to the determining, the assigned two-dimensional rectangular regions are reshaped.

Abstract: A method of controlling a polar optical transmitter comprising a dual-branch Mach-Zehnder (MZ) modulator driven by a pair of independent electrical drive signals. A cost function is provided which defines a relationship between a control parameter of the optical transmitter and a power level of an output optical signal generated by the MZ modulator. A selected component of the electrical drive signals is dithered using a predetermined dither signal. A modulation depth of the output optical signal power level corresponding to the dither signal is detected, and the control parameter adjusted based on the cost function and the detection result.

Abstract: In a coherent optical receiver, a method of at least partially compensating Polarization Dependent Loss (PDL) of an optical signal received through an optical communications system. A respective multi-bit sample stream of each one of a pair of orthogonal received polarizations of the optical signal is tapped, and used to derive a respective metric value indicative of a quality of each multi-bit sample stream. A gain of an analog front end of the coherent optical receiver is adjusted based on the derived metric values.

Abstract: A method of controlling a polar optical transmitter comprising a dual-branch Mach-Zehnder (MZ) modulator driven by a pair of independent electrical drive signals. A cost function is provided which defines a relationship between a control parameter of the optical transmitter and a power level of an output optical signal generated by the MZ modulator. A selected component of the electrical drive signals is dithered using a predetermined dither signal. A modulation depth of the output optical signal power level corresponding to the dither signal is detected, and the control parameter adjusted based on the cost function and the detection result.

Abstract: A method of controlling a polar optical transmitter comprising a dual-branch Mach-Zehnder (MZ) modulator driven by a pair of independent electrical drive signals. A cost function is provided which defines a relationship between a control parameter of the optical transmitter and a power level of an output optical signal generated by the MZ modulator. A selected component of the electrical drive signals is dithered using a predetermined dither signal. A modulation depth of the output optical signal power level corresponding to the dither signal is detected, and the control parameter adjusted based on the cost function and the detection result.

Abstract: A method of controlling a polar optical transmitter comprising a dual-branch Mach-Zehnder (MZ) modulator driven by a pair of independent electrical drive signals. A cost function is provided which defines a relationship between a control parameter of the optical transmitter and a power level of an output optical signal generated by the MZ modulator. A selected component of the electrical drive signals is dithered using a predetermined dither signal. A modulation depth of the output optical signal power level corresponding to the dither signal is detected, and the control parameter adjusted based on the cost function and the detection result.

Abstract: An apparatus for generating variable DGD is particularly for use in a PMD compensator. The apparatus has first, second and third birefringent elements arranged in order between the input and output of the compensator and having first, second and third differential group delays (DGDs) in the ratio 1:2:1. The orientation of the PSPs of the signal in each element relatively to the principal axes of the element is controlled, such that a change in orientation between the first and second elements is equal and opposite to a change in orientation between the second and third elements. This arrangement provides symmetrical relative rotations of the signal PSPs and principal axes about the central birefringent element. In combination with the 1:2:1 ratio, it can be shown that compensation of any first order PMD can be achieved without the compensator introducing additional second order PMD. The required level of first order PMD compensation is selected by controlling the amount of the orientation changes.

Abstract: Generation of variable differential group delay An apparatus for generating variable DGD is particularly for use in a PMD compensator. The apparatus has first, second and third birefringent elements arranged in order between the input and output of the compensator and having first, second and third differential group delays (DGDs) in the ratio 1:2:1. The orientation of the PSPs of the signal in each element relatively to the principal axes of the element is controlled, such that a change in orientation between the first and second elements is equal and opposite to a change in orientation between the second and third elements. This arrangement provides symmetrical relative rotations of the signal PSPs and principal axes about the central birefringent element. In combination with the 1:2:1 ratio, it can be shown that compensation of any first order PMD can be achieved without the compensator introducing additional second order PMD.