Converged ultra-wideband and multi-level wired signal downstream transport over single wavelength in wavelength-division multiplexing passive optical network

Simultaneous providing services of ultra-wideband and wired signal over single wavelength can greatly decrease the complexity and reduce the costs of a wavelength-division multiplexing passive optical network. However, ultra-wideband signal occupies the spectrum range from 3.1 to 10.6 GHz, and a narrow idle frequency band (from 0 to 3.1 GHz) could be employed to transport wired signal with a limited rate. In this paper, we proposed a scheme to simultaneously provide ultra-wideband and wired services, in which the information rate of the wired signal is enhanced by employing a multi-level amplitude switch keying signal in the idle frequency band formed by ultra-wideband signal. In comparison with other advanced modulation formats used for wavelength-division multiplexing passive optical networks such as orthogonal frequency division multiplexing, multi-level amplitude switch keying signal can be easily received by using intensity modulation direct detection, which will greatly reduce the cost of end-users. Especially, if a multi-band ultra-wideband signal is substituted for the direct-sequence ultra-wideband signal, the available spectrum range to transport wired signal will be easily extended to 5 GHz as multi-band ultra-wideband signal has a narrower spectrum width and flexible center frequency, so 4-amplitude switch keying signal with a rate of 5 Gbaud will achieve an information rate of 10 Gbit/s.