Diversity Code Allocation for Distributed Transmit Diversity

Abstract

A method of allocating diversity codes to sectors in a mobile communication network achieves a favorable code balance for all mobile terminals a predetermined percentage of the time. The method comprises allocating diversity codes to each sector in a cluster of sectors for a first time period according to a diversity code pattern, rotating said diversity code pattern relative to said cluster, and allocating diversity codes to each sector in said cluster for a second time period according to said rotated diversity code pattern.

1 . A method of allocating dynamic diversity codes in a mobile communication network, said method comprising: 
 allocating diversity codes to each sector in a cluster of sectors for a first time period according to a diversity code pattern;    rotating said diversity code pattern relative to said cluster; and    allocating diversity codes to each sector in said cluster for a second time period according to said rotated diversity code pattern.    
   
   
       2 . The method of  claim 1  wherein said diversity code pattern is formed from a set of diversity codes.  
   
   
       3 . The method of  claim 2  wherein said diversity codes are space-time diversity codes.  
   
   
       4 . The method of  claim 3  wherein said space-time diversity codes are Alamouti codes.  
   
   
       5 . The method of  claim 2  wherein said diversity codes are space-frequency diversity codes.  
   
   
       6 . The method of  claim 2  wherein said diversity code pattern is such that any three mutually adjacent sectors will include at least two different diversity codes.  
   
   
       7 . The method of  claim 6  wherein said set of diversity codes comprises two diversity codes and wherein said diversity code pattern is such that any three mutually adjacent sectors in said cluster will include each of said diversity codes in said set of diversity codes.  
   
   
       8 . The method of  claim 1  further comprising dynamically changing said diversity code allocation.  
   
   
       9 . The method of  claim 8  wherein dynamically changing said diversity code allocation comprises changing from said dynamic diversity code allocation based on said rotating diversity code pattern to a static diversity code allocation.  
   
   
       10 . The method of  claim 8  wherein dynamically changing said diversity code allocation comprises changing from said dynamic diversity code allocation based on said rotating diversity code pattern to a dynamic code allocation based on an alternating diversity code allocation.  
   
   
       11 . The method of  claim 8  wherein said diversity code pattern is dynanmically changed based on feedback from said mobile stations.  
   
   
       12 . A mobile communication network implementing dynamic diversity codes, said mobile communication network comprising: 
 a plurality of sectors forming a cluster;    wherein each sector in said cluster is assigned a sequence of diversity codes for use during sequential time periods according to a predetermined diversity code pattern, and    wherein said assigned diversity code sequences effects a rotation of said diversity code pattern over said sequential time periods.    
   
   
       13 . The mobile communication network of  claim 12  wherein said diversity code pattern is formed from a set of diversity codes.  
   
   
       14 . The mobile communication network of  claim 13  wherein said diversity codes are space-time diversity codes.  
   
   
       15 . The mobile communication network of  claim 14  wherein said space-time diversity codes are Alamouti codes.  
   
   
       16 . The mobile communication network of  claim 13  wherein said diversity codes are space-frequency diversity codes.  
   
   
       17 . The mobile communication network of  claim 13  wherein said diversity code pattern is such that any three mutually adjacent sectors will include at least two different diversity codes.  
   
   
       18 . The mobile communication network of  claim 17  wherein said set of diversity codes comprises two diversity codes and wherein said diversity code pattern is such that any three mutually adjacent sectors in said cluster will include each of said diversity codes in said set of diversity codes.  
   
   
       19 . A mobile communication network comprising a plurality of sectors forming a cluster, wherein each sector in said cluster is assigned a sequence of diversity codes for use during sequential time periods according to a predetermined diversity code pattern, and wherein said assigned diversity code sequences effects a rotation of said diversity code pattern over said sequential time periods.  
   
   
       20 . The mobile communication network of  claim 19  further including at least one diversity coding circuit for encoding information signals for transmission according to said assigned diversity codes.  
   
   
       21 . The mobile communication network of  claim 20  wherein each sector includes a separate diversity coding circuit for encoding information signals for transmission from said sector according to said assigned diversity codes.  
   
   
       22 . The mobile communication network of  claim 20  wherein said diversity coding circuit encodes information signals transmitted from a group of sectors according to said assigned diversity codes.  
   
   
       23 . The mobile communication network according to  claim 22  wherein said diversity coding circuit is located at a radio base station and encodes information signals from a group of sectors controlled by said radio base station.  
   
   
       24 . The mobile communication network according to  claim 22  wherein said diversity coding circuit is located at a base station controller.  
   
   
       25 . The mobile communication network according to  claim 22  including a centralized diversity coding circuit that encodes information signals transmitted by all sectors in a cluster.  
   
   
       26 . The mobile communication network of  claim 19  further comprising control logic to dynamically change said diversity code allocation.  
   
   
       27 . The mobile communication network of  claim 26  wherein said control logic dynamically switches between said dynamic diversity code allocation based on said rotating diversity code pattern and a static diversity code allocation.  
   
   
       28 . The mobile communication network of  claim 26  wherein said control logic dynamically switches between said dynamic diversity code allocation based on said rotating diversity code pattern and a dynamic diversity code allocation based on an alternating diversity code allocation.  
   
   
       29 . The mobile communication system of  claim 26  wherein said control logic changes the diversity code pattern based on feedback from said mobile terminal