Transmitter and transmitting method increasing the flexibility of code assignment

Abstract

According to the present invention a transmitter and a transmitting method for communicating data symbols over a communication channel, for example, according to the CDMA system is presented. The transmitter ( 24, 25 ) comprises means ( 9 ) for spreading each data symbol with a respective spreading code, wherein the spreading codes are mutually orthogonal. Means ( 10 ) for scrambling are provided to scramble each spread symbol with a respective scrambling code, the scrambling codes respectively having the same length as the spreading codes. Furthermore, means ( 11 ) for the transmission of the spread and scrambled symbols are provided. According to the present invention the means ( 10 ) for scrambling are provided with a plurality of different scrambling codes, which can be used simultaneously within the same link.

What is claimed is: 
     
       1. Transmitter for communicating data symbols over a communication channel, the transmitter comprising:
 means for spreading each data symbol with a respective spreading code, wherein the spreading codes are mutually orthogonal,   means for scrambling each spread symbol with a respective scrambling code, the scrambling codes respectively having the same length as the spreading codes, and   means for transmitting said spread and scrambled symbols,   wherein the means for scrambling are provided with a plurality of different scrambling codes which can be used simultaneously within the same link.   
     
     
       2. Transmitter according to  claim 1 , characterized in that the means for scrambling can use different scrambling codes for an uplink communication channel and a downlink communication channel, respectively. 
     
     
       3. Transmitter according  claim 1 , characterized in that the spreading codes are obtained by means of a code tree. 
     
     
       4. Transmitter according to  claim 1 , characterized in that only in a downlink communication channel different scrambling codes are used, wherein in an uplink channel only one scrambling code is used. 
     
     
       5. Transmitter according to  claim 1 , characterized in that the means for scrambling use different scrambling codes within the same link only for channels demanding a high bit rate. 
     
     
       6. Transmitter according to  claim 5 , characterized in that the means for scrambling use different scrambling codes within the same link only video channels. 
     
     
       7. Wireless transmission system, comprising:
 means for spreading each data symbol with a respective spreading code, wherein the spreading codes are mutually orthogonal,   means for scrambling each spread symbol with a respective scrambling code, the scrambling codes respectively having the same length as the spreading codes, and   means for transmitting said spread and scrambled symbols,   wherein the means for scrambling are provided with a plurality of different scrambling codes which can be used simultaneously within the same link, and   wherein a subset of scrambling codes is respectively allocated to a cell of the transmission system.   
     
     
       8. Wireless transmission system according to  claim 7 , characterized in that different spreading codes are allocated to adjacent cells of the transmission system. 
     
     
       9. Method for the transmission of data symbols over a communication channel, comprising the following steps:
 spreading each data symbol with a respective spreading code, wherein the spreading codes are mutually orthogonal,   scrambling each spread symbol with a respective scrambling code, the scrambling codes respectively having the same length as the spreading codes, and   transmitting said spread and scrambled symbols,   wherein the scrambling step provides a plurality of different scrambling codes which can be used simultaneously within the same link.   
     
     
       10. Method according to  claim 9 , characterized in that in the step of scrambling different scrambling codes can be used for an uplink communication channel and a downlink communication channel, respectively. 
     
     
       11. Method according to  claim 9 , characterized in that the spreading codes are obtained by means of a code tree. 
     
     
       12. Method according to  claim 9 , characterized in that only in a downlink communication channel different scrambling codes are used, wherein in an uplink channel only one scrambling code is used. 
     
     
       13. Method according to  claim 9 , characterized in that different scrambling codes within the same link are used only for channels demanding a high bit rate. 
     
     
       14. Method according to  claim 13 , characterized in that different scrambling codes within the same link are used only for video channels. 
     
     
       15. A method for transmitting data symbols over an uplink or a downlink, each link having first and second communication channels, comprising:
 spreading each data symbol for the first communication channel, using a spreader unit, with an associated spreading code, thereby producing a corresponding spread data symbol for each data symbol for the first communication channel in an uplink or a downlink;   spreading each data symbol for the second communication channel, using a spreader unit, with an orthogonal spreading code, orthogonal to the associated spreading code for the first communication channel, thereby producing a corresponding spread data symbol for each data symbol for the second communication channel in the uplink or the downlink;   scrambling, using a scrambling unit, each spread data symbol of the first communication channel with a primary scrambling code, thereby producing a corresponding scrambled symbol for each spread data symbol of the first communication channel;   scrambling, using a scrambling unit, each spread data symbol of the second communication channel with a secondary scrambling code, thereby producing a corresponding scrambled symbol for each spread data symbol of the second communication channel; and   transmitting, using a transmitter, said corresponding scrambled symbols,   wherein the primary and secondary scrambling codes for the downlink are different from each other and the primary and secondary scrambling codes for the uplink are the same as each other,   wherein a resulting data rate is spread over two or more of the scrambled codes.   
     
     
       16. The method according to claim 15, wherein the primary or secondary scrambling code does not effect a band rate of the transmission. 
     
     
       17. A method for transmitting one or more data symbols over an uplink or a downlink at data rates, each link having a first communication channel and a second communication channel, comprising:
 providing the one or more data symbols to the first communication channel and the second communication channel in an uplink or a downlink;   spreading each data symbol for the first channel, using a spreader unit, with a first spreading code, producing a first spread data symbol;   spreading each data symbol for the second channel, using a spreader unit, with a second spreading code, producing a second spread data symbol,   wherein the first spreading code and the second spreading code are mutually orthogonal,   scrambling, using a scrambling unit, the first spread data symbol with a primary scrambling code;   scrambling, using a scrambling unit, the second spread data symbol with a secondary scrambling code; and   providing, using a scrambling unit, a plurality of different scrambling codes for the communication channels in the uplink or the downlink, the scrambling codes being configured simultaneously within the same link, the scrambling codes for the communication channels in the downlink are different from each other when the data symbols in the downlink are of a data rate higher than a voice data rate, and the scrambling codes for the communication channels in the downlink are the same as each other when the data symbols in the downlink are of a data rate equal to or lower than the voice data rate,   wherein a resulting data rate is spread over two or more of the plurality of different scrambled codes.   
     
     
       18. The method of transmitting according to claim 17 wherein the plurality of different scrambling codes comprise a portion of the primary scrambling code and a portion of the secondary scrambling code.