System and method for channel transport format allocation in a wireless communication system

Abstract

A wireless communication system and method employing channel transport format allocation in a shared uplink channel between a UE and a Node B, and wherein the UE can determine a transport format combination which it can support, by: detecting in the UE a change in transport format combination that the UE can support; and sending to the Node B an indication of transport format combination that the UE can support, whereby efficiency of channel transport format allocation in the system may be improved. A conditional delay mechanism may be employed to reduce signalling overhead. This allows uplink shared channels to be efficiently used by providing a means by which UTRAN (UMTS terrestrial radio access network) is informed of the TFCs within the TFCS which can be used in the uplink by the UE.

The invention claimed is: 
     
       1. A method for a wireless communication system using transport format combinations (TFC) for allocating bandwidth of a shared channel among a plurality of radio units in the system performed by a radio unit, the method comprising:
 receiving, at a the radio unit, a transport format combination set (TFCS) including a transport format combination (TFC) allocated for use by the radio unit for data transmission; 
 detecting in the radio unit that the radio unit can change to and support a TFC within the TFCS different from the allocated TFC; and 
 sending, responsive to the detecting, to the a base station an indication of the transport format combination TFC in the TFCS that the radio unit can support; and 
 conditionally delaying sending the indication, until the detected change in the TFC that the radio unit can support has lasted for more than a predetermined time period. 
 
     
     
       2. The method as claimed in  claim 1 , further comprising, conditionally delaying sending the indication, until the detected change in transport format combination that the radio unit can support has lasted for more than a predetermined period of time. 
     
     
       3. The method as claimed in  claim 1 , wherein the allocated TFC refects reflects an allocation of an uplink shared channel among the a plurality of radio units in the system. 
     
     
       4. The mothod as claimed in  claim 1 , wherein the radio unit is part of a UMTS system. 
     
     
       5. The method as claimed in  claim 4 , wherein the step of detecting further comprises: indicating from physical interface circuitry to medium access control circuitry a change in transport format combination that he radio unit can support. 
     
     
       6. The method as claimed in  claim 5 , wherein the step of indicating further comprises providing, to the base station, calculated transport format combinations that the radio unit cab support. 
     
     
       7. A wireless unit for data transmission on an unlink channel shared with other wireless units, the uplink channel shared by allocating a transport format combination (TFC) to the wireless unit from a basestation, the wireless unit comprising:
 physical interface circuitry configured to detect Transport Format Combinations (TFCs) that the wireless unit can use; and 
 media access control circuitry configured to receive, from the physical interface circuitry, an indication information of the TFCs that the wireless unit can use, and to select, for uplink transmission, a TFC from the TFCs that the wireless unit can use, and wherein the media access control circuitry is also configured to provide an indication to the a basestation if the selected TFC is not the an allocated TFC from the basestation; and 
 a timer configured to prevent transmission of the indication to the basestation unless a change to the selected TFC has continued for at least a predetermined time period. 
 
     
     
       8. The wireless unit of  claim 7 , further comprising a timer configured to prevent transmission of the indication to the basestation unless the detected change has continued for at feast a predetermined period of time. 
     
     
       9. The wireless unit of  claim 7 , wherein the wireless unit is configured to operate in a UMTS system. 
     
     
       10. The wireless unit of  claim 7 , wherein the physical interface circuitry is configured to provide calculated TFCs as the indication information provided to the media access controller circuitry. 
     
     
       11. A computer readable medium comprising program code for a method of allocating bandwidth of a shared wireless medium, the method comprising:
 receiving, in a radio unit and from a controller, a transport format combination representative of an allocation of a shared uplink channel;   detecting, in the radio unit, a change in Transport Format Combinations (TFC) that the radio unit can use for an uplink transmission; and   indicating the TFC change to the controller so that the controller can use the indication for reallocating the shared unlink channel.   
     
     
       12. A computer readable medium comprising program code for a method to be implemented in a controller for a wireless communications network that provides for uplink transmissions from a plurality of wireless units on a shared channel, the method comprising:
 formulating a first set of transport format combinations (a TFCS), for transmission to a wireless unit of the plurality, the first TFCS reflecting an allocation of the shared channel among the plurality of wireless units, and including an initially allocated TFC for unlink transmission by the wireless unit;   transmitting the first TFCS to the wireless unit;   receiving an indication from the wireless unit that a calculated set of TFCs that the wireless unit can use for an uplink transmission differs from the initially allocated TFC in the first TFCS; and   modifying the allocation of the shared channel among the wireless units in response to the indication.   
     
     
       13. The computer readable medium of  claim 12 , the stored method further comprising:
 determining, based on the indication, that the initially allocated TFC provides a bandwidth higher than what the wireless unit can presently use; and   further comprising reallocating, to other wireless units of the plurality, a difference in bandwidth reflected by the highest bandwidth TFC in the calculated set of TFC and the initially allocated TFC in the first TFCS.   
     
     
       14. The computer readable medium of  claim 12 , the stored method further comprising:
 determining, based on the indication, that the wireless unit can use a higher bandwidth TFC in the first TFCS than the initially allocated TFC; and   allocating the higher bandwidth TFC to the wireless unit.   
     
     
       15. A user equipment (UE) comprising:
 circuitry configured to select a first transport format combination (TFC) from a plurality of TFCs;   circuitry configured to determine whether a second TFC is supported by a comparison of a transmission power of the second TFC to a maximum UE transmit power, wherein the second TFC has a higher data rate than the first TFC;   circuitry configured in response to the second TFC being supported, to transmit data using the first TFC and an indication that a higher data rate TFC is supported; and   circuitry configured to receive an allocation of uplink resources in response to the indication.   
     
     
       16. The UE of claim 15 wherein the determination whether the second TFC being supported occurs for a plurality of measurement periods. 
     
     
       17. The UE of claim 15 further comprising:
 the circuitry configured to receive a transport format combination set (TFCS); and   wherein the second TFC is selected from the TFCS.   
     
     
       18. The UE of claim 15 wherein the allocation of uplink resources is for an uplink shared channel. 
     
     
       19. A Node B comprising:
 circuitry configured to transmit information to communicate a plurality of transport format combinations (TFCs) for uplink transmission to a user equipment (UE);   circuitry configured to receive data using a first TFC from the UE and an indication that a higher data rate TFC is supported by the UE, wherein the first TFC is selected from the plurality of TFCs; and   circuitry configured to transmit an allocation of uplink resources in response to the indication.   
     
     
       20. The Node B of claim 19 wherein the allocation of uplink resources is for an uplink shared channel. 
     
     
       21. A method performed by a user equipment (UE), the method comprising:
 selecting, by the UE, a first transport format combination (TFC) from a plurality of TFCs;   determining, by the UE, whether a second TFC is supported by comparing a transmission power of the second TFC to a maximum UE transmit power, wherein the second TFC has a higher data rate than the first TFC;   transmitting, by the UE in response to the second TFC being supported, data using the first TFC and an indication that a higher data rate TFC is supported; and   receiving, by the UE, an allocation of uplink resources in response to the indication.   
     
     
       22. The method of claim 21 wherein the determining whether the second TFC being supported occurs for a plurality of measurement periods. 
     
     
       23. The method of claim 21 further comprising:
 receiving, by the UE, a transport format combination set (TFCS); and   wherein the second TFC is selected from the TFCS.   
     
     
       24. The method of claim 21 wherein the allocation of uplink resources is for an uplink shared channel. 
     
     
       25. A method performed by a Node B, the method comprising:
 transmitting, by the Node B, information communicating a plurality of transport format combinations (TFCs) for uplink transmission to a user equipment (UE);   receiving, by the Node B, data using a first TFC from the UE and an indication that a higher data rate TFC is supported by the user equipment, wherein the first TFC is selected from the plurality of TFCs; and   transmitting, by the Node B, an allocation of uplink resources in response to the indication.   
     
     
       26. The method of claim 25 wherein the allocation of uplink resources is for an uplink shared channel.