Patent ID: 7593646

Claim:
A wavelength division multiplexed (WDM) optical communication system, comprising: an upgraded transmitter utilized in place of a replaced transmitter that transmitted payload data over a channel at a defined bit rate, the upgraded transmitter operable to transmit the payload data and at least one other payload data in a combined M-ary phase shift keying (mPSK) signal having a combined bit rate of at least twice a system designed bit rate and a symbol rate approximately equal to the system designed bit rate; an upgraded receiver utilized in place of a replaced receiver that recovered the payload data at the defined bit rate, the upgraded receiver operable to recover the payload data and the at least one other payload data from the mPSK signal having the symbol rate approximately equal to the system designed bit rate; and post-transmitter, in-line and pre-receiver optical components configured for the defined bit rate utilized to communicate the mPSK signal between the upgraded transmitter and the upgraded receiver at the combined bit rate.