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For low-cost passive optical access networks (PON), we have studied the downstream delivery of an additional >1 Gb/s in the passband above the 155-Mb/s baseband signal. Both signals are transmitted on the same fiber using a single transmitter and a single receiver within the power budgets of ITU-T G983. The passband approach offers a graceful upgrade of a 155-Mb/s baseband system, and is compatible with baseband only optical network unit (ONU). We multiplexed a 155.52-Mb/s baseband signal with QPSK modulated passband>1.2 Gb/s of broadcast DSS digital video channels in the 270-1450-MHz range through a diplexer with minimal degradation. For a passband test-signal, we used an additional 8-Mb/s QPSK modulated 860-MHz carrier. An optical to electrical (O/E) receiver using a p-i-n diode satisfies the need for class B operation as defined in ITU-T G983 (-30 dBm receiver sensitivity) for a 10/sup -10/ bit-error rate. However, an APD based receiver satisfies the power budget needs of ITU-T G983 with /spl sim/5.5 dBo margin for class C operation (-33-dBm receiver sensitivity) for both baseband and passband signals.
Date of Publication: Sept. 1999