초록 ▼

An orthogonal code division multiple access (OCDMA) communication system having multicarrier modulation. The incoming input data stream is broken into multiple parallel streams, each of which modulates its own frequency-division multiplexed carrier. This reduces the chipping rate such that the delay

An orthogonal code division multiple access (OCDMA) communication system having multicarrier modulation. The incoming input data stream is broken into multiple parallel streams, each of which modulates its own frequency-division multiplexed carrier. This reduces the chipping rate such that the delay spread does not cause excessive access noise. Particularly robust delay lock loop (DLL) code tracking and particularly robust automatic frequency control (AFC) are provided in the presence of frequency-selective fading.

대표청구항 ▼

[ What is claimed is:] [1.] In an orthogonal code division multiple access (OCDMA) communication system having at least one base station and a plurality of remote subscriber terminals, a modulation system for reducing sensitivity of OCDMA to access noise created by time base error and delay spread,

[ What is claimed is:] [1.] In an orthogonal code division multiple access (OCDMA) communication system having at least one base station and a plurality of remote subscriber terminals, a modulation system for reducing sensitivity of OCDMA to access noise created by time base error and delay spread, comprising: means to divide an incoming data stream into multiple parallel data streams, means providing a corresponding plurality of frequency division multiplexed carriers, means providing a corresponding plurality of carrier channels connected to receive respective ones of said multiple parallel data stream, modulator means in each of said channels, each carrier channel having an output, means to sum the outputs of each modulator of the modulator means to produce a composite multicarrier waveform signal, means spreading said composite multicarrier waveform signals with a selected PN/RW code, and means to convert the spread composite multicarrier waveform signal to a desired broadcast frequency, amplify and transmit to remote subscriber terminals.