Patent ID: 9160480
Filing Date: 2015-10-13
Classification: H04J

Abstract:
1. A method by an optical network unit ONU comprising the steps of: i) for downstream transmission, using a first tunable laser for coherent detection on a sub-band basis to increase receiver sensitivity and reduce analog-to-digital conversion (ADC) and digital signal processor (DSP) requirements within said ONU; and ii) for upstream transmission, using a second tunable laser and using an optical signal beating between said first and second tunable lasers to generate a tunable radio frequency RF signal source for upstream multi-band orthogonal frequency-division multiple access (OFDMA) signal generation thereby avoiding an RF clock source within said ONU, as well as enabling digital-to-analog conversion (DAC) operation and rendering said ONU colorless in both optical and radio frequency RF domains; wherein step i) comprises a downstream multi-band OFDMA signal being routed via a circulator to a coherent optical receiver (Rx) and to recover one or more of several possible OFDMA sub-bands in the multi-band OFDMA signal, a wavelength of a first tunable local oscillator LO wherein an amount of needed frequency shift for said first tunable local oscillator LO