Dynamic Direction Changing in Time Division Duplex Radios

Abstract

In accordance with some embodiments, in a time division duplex system, the transmission direction may be changed dynamically, for example in response to instantaneous traffic conditions. Particularly in some embodiments an eNodeB or base station may, in response to instantaneous traffic conditions, change the direction of transmission in certain subframes. In some embodiments this can be done in a way which is backwards compatible with prior generations of Long-Term Evolution (LTE) radio systems.

What is claimed is: 
     
         1 . A computer executed method comprising:
 transmitting a fixed uplink-downlink configuration of frame structure type 2 through a system information message in a time division duplex long-term evolution system;   setting a first subframe to be switched between uplink and downlink transmission directions;   pairing the first subframe with a second subframe that is not switchable between uplink and downlink transmission directions; and   providing an indication signal in said second subframe to indicate a change of transmission direction of the first subframe.   
     
     
         2 . The method of  claim 1  including maintaining said first subframe in a default transmission direction and changing a transmission direction of a data region of said first subframe from a default transmission direction to an uplink direction upon detection of said indication signal. 
     
     
         3 . The method of  claim 2  including monitoring the second subframe in every radio frame to detect the indication signal. 
     
     
         4 . The method of  claim 2  wherein said default transmission direction is a downlink direction determined by an uplink-downlink configuration. 
     
     
         5 . The method of  claim 2  wherein the said indication signal is an uplink grant transmitted in the second subframe to trigger transmission in the first subframe. 
     
     
         6 . The method of  claim 1 , said first subframe including one control region and one data region and multiplexing in Time Domain Multiplexing. 
     
     
         7 . The method of  claim 6 , including changing the data region of said first subframe from a default transmission direction to an uplink direction and transmitting on the said first subframe following detection of the said indication signal and maintaining the control region of said first subframe in the default transmission direction upon detection of said indication signal. 
     
     
         8 . The method of  claim 7  including providing a guard period between uplink transmission and downlink reception to accommodate a timing advance or switching delay. 
     
     
         9 . The method of  claim 8 , including providing, in the data region of said first subframe, a guard period between uplink transmission and downlink reception at the user equipment side to accommodate a timing advance or switching delay and a data period following the guard period for physical uplink shared channel transmission. 
     
     
         10 . The method of  claim 1  including setting a time division duplex configuration to enable pairing of subframes. 
     
     
         11 . The method of  claim 10 , wherein the first subframe is subframe  8  and the second subframe is subframe  4  in the same radio frame ‘i’, assuming subframe index numbering from 0 within radio frame T. 
     
     
         12 . The method of  claim 8 , wherein the first subframe is subframe  3  in the radio frame ‘i+1’ and the paired second subframe is subframe  9  in the radio frame ‘i’, assuming subframe index starting from 0 within each radio frame. 
     
     
         13 . The method of  claim 1 , wherein the fixed uplink-downlink configuration of frame structure type 2 is uplink-downlink configuration  2  of frame structure type 2. 
     
     
         14 . The method of  claim 1 , wherein the system information is System Information Block  1 . 
     
     
         15 . One or more non-transitory computer readable media storing instructions to perform a sequence comprising:
 switching a first subframe between uplink and downlink transmission directions in a time division duplex long-term evolution system;   pairing the first subframe with a second subframe that is not switchable between uplink and downlink transmission directions; and   indicating in said second subframe a change of transmission direction of the first subframe.   
     
     
         16 . The media of  claim 15  including maintaining said first subframe in a default transmission direction and changing a transmission direction of a data region of said first subframe from a default transmission direction to an uplink direction upon detection of a signal indicating a change of transmission direction. 
     
     
         17 . The media of  claim 16  wherein the said signal is an uplink grant transmitted in the second subframe to trigger transmission in the first subframe. 
     
     
         18 . The media of  claim 15 , said first subframe including one control region and one data region and multiplexing in Time Domain Multiplexing. 
     
     
         19 . The media of  claim 15  including setting a time division duplex configuration to enable pairing of subframes. 
     
     
         20 . The media of  claim 19 , wherein the first subframe is subframe  8  and the second subframe is subframe  4  in the same radio frame ‘i’, assuming subframe index numbering from 0 within radio frame T. 
     
     
         21 . The media of  claim 19 , wherein the first subframe is subframe  3  in the radio frame ‘i+1’ and the paired second subframe is subframe  9  in the radio frame ‘i’, assuming subframe index starting from 0 within each radio frame. 
     
     
         22 . A time division duplex long-term evolution radio device comprising:
 a processor to switch a first subframe paired with a second subframe, from an uplink to a downlink transmission direction using a signal in said second subframe;   a memory coupled to said processor; and   a radio transmitter coupled to said processor.   
     
     
         23 . The device of  claim 22  wherein said device is an eNodeB. 
     
     
         24 . The device of  claim 22  said processor to maintain said first subframe in a default transmission direction and changing a transmission direction of a data region of said first subframe from a default transmission direction to an uplink direction upon detection of said indication signal. 
     
     
         25 . The device of  claim 22  said processor to monitor the second subframe in every radio frame to detect the indication signal. 
     
     
         26 . The device of  claim 22  wherein said default transmission direction is a downlink direction determined by an uplink-downlink configuration. 
     
     
         27 . The device of  claim 22  wherein said signal is an uplink grant transmitted in the second subframe to trigger transmission in the first subframe. 
     
     
         28 . The device of  claim 22 , said first subframe including one control region and one data region and said device to multiplex using Time Domain Multiplexing. 
     
     
         29 . The device of  claim 22 , said processor to change the data region of said first subframe from a default transmission direction to an uplink direction and transmit on the said first subframe following detection of the said signal. 
     
     
         30 . A time division duplex long-term evolution radio device comprising:
 a processor to detect a signal in a second subframe and in response thereto, switch the transmission direction of a first subframe;   a memory coupled to said processor; and   a radio transmitter coupled to said processor.   
     
     
         31 . The device of  claim 30  when said device is user equipment. 
     
     
         32 . The device of  claim 30  where said first subframe is paired with said second subframe, and said second subframe has a fixed transmission direction.