Method and system for code division multiple access communication with increased capacity through self-noise reduction

A method of constructing binary codes for use in a network utilizing quasi-synchronous code division multiple access combined with time division duplexing from a combination of two different sets of codes, the method comprising:

• providing a first code of one of the sets as a generator;
• providing a second code of one of the sets as a seed;
• replacing a bit of the first code by the corresponding bit of the second code if the corresponding bit is a zero, or replacing the bit by the bit-inverse of the corresponding bit of the second code if the corresponding bit is a one;
• and
• applying the resulting code to a plurality of data streams in the network so as to provide spread spectrum data streams.

A method of fast acquisition of auto-correlation peaks for use in a network utilizing quasi-synchronous code division multiple access combined with time division duplexing, using codes with equally-spaced peaks, the method comprising:

• searching for a auto-correlation peak;
• testing for the validity of the choice;
• if the choice is not correct, testing the next auto-correlation peak;
• and
• if the choice is correct, applying the chosen codes to a plurality of data streams in the network so as to provide spread spectrum data streams.

A time division duplex communication system using synchronous code division multiple access (S-CDMA) communication in the forward link between one master station and multiple slave stations, and quasi synchronous code division multiple access (QS-CDMA) in the return link between the multiple slave stations, the system comprising:

• a master station transmit cycle configured to:
• synchronize the slave stations to a beacon signal transmitted by the master station,
• acknowledge each of the codes by the one master station from a slave station transmit cycle received from any successfully demodulated slave stations, and
• transmit direct spread data to any earlier already acknowledged slave stations;
• the slave station transmit cycle configured to:
• transmit, by each slave station having obtained the synchronization, a code selected from a list to the master station, or
• transmit data, direct spread by the code from slave stations already having received the acknowledgement from the master station transmit cycle;
• and
• a repeat loop to return the system to the master station transmit cycle.

A method of constructing non-binary digital orthogonal code sequences of length N, with N any natural number, for use in a network utilizing quasi-synchronous code division multiple access combined with time division duplexing, the method comprising:

• providing a unity base in an N-dimensional vector space, V, having operations comprising addition of vectors (+) and scalar product of vectors (.);
• applying consecutive base transformations to the base;
• representing the resulting base vectors by their coordinates in the N-dimensional vector space to obtain a set of orthogonal codes;
• and
• applying the set of orthogonal codes to a plurality of data streams in the network so as to provide spread spectrum data streams.