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 ▼

[ What is claimed is:] [1.] A transmitter for a code division multiplexed system, comprising:a framer circuit to receive input data and rearrange said input data into a plurality of subgroups of bits for encoding;an encoder coupled to receive each subgroup and having circuitry and a state memory to

[ What is claimed is:] [1.] A transmitter for a code division multiplexed system, comprising:a framer circuit to receive input data and rearrange said input data into a plurality of subgroups of bits for encoding;an encoder coupled to receive each subgroup and having circuitry and a state memory to analyze each subgroup of bits and the previous states to add one or more redundant bits to each subgroup to generate symbol elements referred to as chips;a memory to receive said datas and store them in groups as a plurality of symbols, said plurality of symbols defining an information vector;a code division multiplexer having circuitry coupled to said memory to multiply each information vector stored In said memory times the orthogonal spreading codes in an orthogonal code matrix to generate a result vector of spread spectrum chip data for each information vector; anda modulator for modulating the spread spectrum chip data of each said result vector onto one or more radio frequency carriers.