Method for allowing multi-user orthogonal and non-orthogonal interoperability of code channels

Abstract

A technique for allowing a first and second group of users to share access to a communication channel such as a radio channel. A first group of users is typically a legacy group of users such as those using digital CDMA cellular telephone equipment. The second group of users are a group of data users that code their transmissions in different formats optimized for data functionalities. The first group of users share one modulation structure such as, on a reverse link, using unique phase offsets of a common pseudorandom noise (PN) code. The second group of users share another modulation structure but in a manner that is consistent and compatible with the users of the first group. Specifically, the users of the second group may all use the same PN code and code phase offset. However, they are uniquely identified such as, for example, assigning each of them a unique orthogonal code.

1 . In a system which supports code division multiple access communication among members of a first group of terminals and among a second group of terminals, a method comprising the steps of: 
 assigning to the first group of terminals a first code, each user of the first group being uniquely identifiable by a unique code phase offset;    assigning to the second group of terminals the same code as used by the first group but each user of the second group using a common phase offset of that code; and    assigning to each user of the second group an additional code, the additional code being unique for each of the terminals of the second group.    
   
   
       2 . A method as in  claim 1  wherein the code assigned to the first group of terminals is a common chipping rate code.  
   
   
       3 . A method as in  claim 1  wherein the additional codes assigned to the second group of terminals are a set of unique, orthogonal codes.  
   
   
       4 . A method as in  claim 1  wherein the code assigned to the first group of terminals is a unique, non-orthogonal scrambling sequence.  
   
   
       5 . A method as in  claim 1  wherein the first group of terminals uses scrambling codes that are unique phase shifts of a larger pseudorandom noise sequence.  
   
   
       6 . A method as in  claim 1  wherein the second group of terminals use additional codes that are a set of unique orthogonal codes.  
   
   
       7 . A method as in  claim 6  wherein the unique orthogonal code is used to scramble the transmissions of the second group of terminals at an indicated chip rate.  
   
   
       8 . A method as in  claim 7  wherein the transmission timing for the second group of terminals is synchronized to allow transmissions from the second group of terminals to be orthogonal to one another.  
   
   
       9 . A method as in  claim 1  wherein the two groups of terminals employ radio frequency modulation that is different from each other.  
   
   
       10 . A method as in  claim 1  wherein the two groups of terminals employ the codes in different spreading techniques.  
   
   
       11 . A wireless communication system comprising a first set of access units and a second set of access units, the first set of access units and the second set of access units capable of communicating with a central base station wherein the first set of access units use a chip rate scrambling code to separate their user channels, each individual unit of the first set of access units having at least one unique, non-orthogonal scrambling sequence that is selected from a unique phase shift of a longer pseudorandom noise sequence, and wherein the second group of access units share a common chip rate scrambling code that is not used by the first group of access units.  
   
   
       12 . The wireless communication system of  claim 11  wherein each unit of the second set is assigned at least one unique orthogonal code.  
   
   
       13 . The wireless communication system of  claim 11  wherein the chip rate transmissions of the second set of access units are scrambled by the bits of the orthogonal code at a chipping rate.  
   
   
       14 . The wireless communication system of  claim 11  wherein the transmission timing of the second set of access units is controlled such that their transmissions are orthogonal to each other.  
   
   
       15 . The wireless communication system of  claim 11  wherein the scrambling code is 2 42  chips in length.  
   
   
       16 . The wireless communication system of  claim 11  wherein the first set of access units and the second set of access units employ different modulation techniques.  
   
   
       17 . The wireless communication system of  claim 11  wherein the first set of access units and the second set of access units employ different spreading techniques.  
   
   
       18 . The wireless communication system of  claim 17  wherein the first set of access units employ complex in-phase and quadrature spreading.  
   
   
       19 . The wireless communication system of  claim 18  wherein the complex in-phase and quadrature spreading uses two different scrambling codes.  
   
   
       20 . The wireless communication system of  claim 19  wherein the two different scrambling codes are 2 15  in length.