Scheme for spread spectrum multiple access coding

Abstract

This invention publishes a spread spectrum multiple access coding technique applied in any wireless digital telecommunication system involving Code Division Multiple Access and spread spectrum technique. The group of basic pulses has normalized amplitudes and duration of 1 and polarity; the number of basic pulses is ascertained by practical factors; there is no equal interval between basic pulses on time axis, and asymmetry of pulses' positions is employed to achieve arranging coding. This coding scheme can control and minimize the side lobes of auto-correlation and cross-correlation functions, then simplify the design of a CDMA system, so a wireless digital telecommunication system with large capacity can be established effectively to solve the contradiction between ever increasing demand for telecommunication capacity and limited frequency resources.

What is claimed is:  
     
         1 . A method comprising: 
 forming a spread spectrum access code including basic pulses that have normalized amplitude, a duration of and polarity;    determining the number of basic pulses;    using the pulse positions which characterize in various intervals between these basic pulses on time axis and orders of pulses' polarities to encode said pulses.    
     
     
         2 . The method of  claim 1  including causing only one of the intervals between said basic pulses on a time axis to be an arbitrary odd number greater than minimal interval, such that that the coding length is an odd number, and the interval between any pair of basic pulses on a time axis can not be the sum of any combination of no less than two other intervals.  
     
     
         3 . The method of  claim 2  wherein said spread spectrum multiple access codes comprise a spread spectrum multiple access code group according to orthogonality, and determining the polarities of basic pulses by orthogonality of the spread spectrum access code.  
     
     
         4 . The method of  claim 2  including forming said basic pulse of pulse compression codes, derived from one or more binary or multi-nary sequences.  
     
     
         5 . The method of  claim 2  including time-offsetting and overlapping the spread spectrum access code.  
     
     
         6 . The method of  claim 5  including adopting different orthogonal modulating frequencies for different versions of time-offset spread spectrum multiple access code sequences.  
     
     
         7 . The method of  claim 2  including deriving said orthogonal pulse compression codes from one or more groups of binary or multi-nary sequences  
     
     
         8 . The method of  claim 2  including adopting different orthogonal modulating frequencies.  
     
     
         9 . The method of  claim 2  including coding with recomposition of said intervals of basic pulses on the time axis.