초록 ▼

A method and apparatus for carrying out synchronous co-division multiple access (SCDMA) communication of multiple channels of digital data over a shared transmission media such as a cable television system coaxial cable, a fiber optic or copper conductor telephone link, terrestial microwave, satelli

A method and apparatus for carrying out synchronous co-division multiple access (SCDMA) communication of multiple channels of digital data over a shared transmission media such as a cable television system coaxial cable, a fiber optic or copper conductor telephone link, terrestial microwave, satellite link, local or wide area network, wireless including cellur network or some combination of these media using suitable interface circuitry. The system includes modems at remote units and a central unit to receive time division multiplexed digital data arranged into timeslots or channels and uses orthogonal codes to encode each channel of multiple data and spread the energy of each channel data over a frame of data transmitted in the code domain. Spreading the data this way makes the system less susceptible to impulse noise. Frames are synchronized as between remote and central units using a ranging scheme which is also useful in any other system transmitting data by frames in a distributed system where synchronizing the frames as between all units regardless of differences in propagation delays is necessary. Each frame in the SCDMA modulation scheme includes a gap or guardband containing no other data. The ranging process involves training each remote unit to impose enough delay prior to re-transmission of a barker code received from the CU such that a barker code sent by the RU arrives at the CU during the gap. The process of setting the delay in each RU is a trial and error process, and each RU starts the ranging process asynchronously. Contention resolution protocols such that only one RU is aligning to the gap at any particular time are taught.

대표청구항 ▼

1. A method for transmitting multiple channels of digital data encoding supplemental services from a plurality of remote transceivers to a headend transceiver, said transmission carried out over a transmission media simultaneously with transmissions carrying other services, comprising:receiving mult

1. A method for transmitting multiple channels of digital data encoding supplemental services from a plurality of remote transceivers to a headend transceiver, said transmission carried out over a transmission media simultaneously with transmissions carrying other services, comprising:receiving multiple channels of digital data that has been encoded with supplemental services, said channels of digital data organized as a time division multiple access stream with multiple timeslots, each timeslot corresponding to one upstream logical channel, one or more timeslot assigned to carry data from each channel; selecting portions of said digital data from each channel and organizing said portions as an information vector having n elements and inserting known preamble data into at least some information vectors; performing code division multiplexing by performing a matrix multiplication of said information vector times a code matrix comprised of n orthogonal, cyclic spreading codes using a chip clock which is synchronized to a chip clock in said headend transceiver, each code assigned to one said channel and comprising one row or one column of said code matrix and having n elements, said matrix multiplication generating a spread spectrum result vector having n elements; using the n elements of said result vector to create the information content in one or more radio frequency signals each radio frequency signal being synchronized in frequency with a local oscillator signal in said headend transceiver and each radio frequency signal being selected and filtered so as to have a center frequency and bandwidth so as to not interfere with said other services and transmitting said resulting radio frequency signals on said transmission media.