Transmission rate change in communications networks

Abstract

A communications network includes first and second stations ( 10, 20 ), the first station ( 10 ) comprising a transmitter ( 18 ) and the second station ( 20 ) comprising a receiver ( 22 ). The network comprises a transition control portion ( 14 ) which is operable, prior to a change in a transmission rate of a preselected signal from the first station ( 10 ) to the second station ( 20 ), to cause transitional signals to be transmitted from the first station ( 10 ) to the second station ( 20 ) over the course of a transitional period expiring before the change is effected. The power levels of the transitional signals are varied over the course of the period in such a way as to reduce a level of instability in the network that would otherwise result from a transmission power change required by the change in transmission rate of that signal. In another embodiment ( FIG. 9 ) probing signals are transmitted prior to making such a rate change to probe a likely relationship between the transmission rate and transmission power after the change is effected.

1 - 9 . (canceled)  
     
     
         10 . A communications network comprising first and second stations, said first station comprising a transmitter and said second station comprising a receiver, the network further comprising: 
 a probing unit operable, prior to a change in a transmission rate of a preselected signal from said first to said second station, to cause probing signals to be transmitted from said first station to said second station at one or more probing power levels and further operable to measure results of transmission of said probing signals at said one or more power levels and to employ the measurement results to provide information relating to a likely relationship between a transmission rate of said predetermined signal and a transmission power thereof when the change is effected.    
     
     
         11 . A communications network as claimed in  claim 10 , wherein said information is a transmission rate considered to be achievable at a preselected power level of said predetermined signal when said change is effected.  
     
     
         12 . A communications network as claimed in  claim 10 , wherein said information is a power level at which said predetermined signal is to be transmitted, when said change is effected, to achieve a preselected transmission rate.  
     
     
         13 . A communications network as claimed in  claim 10 , wherein said information comprises both a suggested transmission rate and a suggested transmission power suitable for use when said change is effected.  
     
     
         14 . A communications network as claimed in  claim 10 , wherein said information is a decision result indicating whether or not a preselected transmission rate is achievable at a transmission power level within a preselected range of allowable power levels of said first station.  
     
     
         15 . A communications network as claimed in  claim 10 , wherein said information is a decision result indicating whether or not a preselected transmission rate is achievable at a preselected transmission power level.  
     
     
         16 . A communications network as claimed in  claim 10 , wherein the power levels of said probing signals are varied in such a way as to reduce a level of instability in the network that would otherwise result from a transmission power change required by said change in transmission rate of said preselected signal.  
     
     
         17 . A communications network as claimed in  claim 10 , wherein said results are measured in said first station.  
     
     
         18 . A communications network as claimed in  claim 10 , wherein said results are measured in said second station and said second station comprises a transmission unit operable to transmit such measurement results to said first station.  
     
     
         19 . A communications network as claimed in  claim 10 , wherein said one or more probing power levels at which said probing signals are transmitted are set in dependence upon said measurement results.  
     
     
         20 . A communications network as claimed in  claim 10 , wherein said measurement results indicate a level of interference being experienced in the network.  
     
     
         21 . A communications network as claimed in  claim 10 , wherein he said measurement results comprise one or more measures of signal-to-interference ratio of said probing signals.  
     
     
         22 . A communications network as claimed in  claim 10 , wherein said change in transmission rate is an increase in the transmission rate of said preselected signal.  
     
     
         23 . A communications network as claimed in  claim 10 , wherein the probing unit is operable to set at least one of said probing power levels in dependence upon an estimate of the power level at which the preselected signal is required to be transmitted, when said change is effected, to achieve a target transmission rate.  
     
     
         24 . A communications network as claimed in  claim 23 , wherein said probing signals are transmitted at least two different probing power levels spanning a range of power levels that includes said estimate of the required power level.  
     
     
         25 . A communications network as claimed in  claim 10 , wherein said probing unit is operable to perform such measurement of the results of transmission of the probing signals after transmission of a last one of said probing signals.  
     
     
         26 . A communications network as claimed in  claim 10 , wherein said probing unit is operable to perform such measurement of the results of transmission of the probing signals during the course of transmission of those signals.  
     
     
         27 . A communications network as claimed in  claim 26 , wherein said probing unit is operable to measure the results of the transmission of the probing signals at each different one of said probing power levels.  
     
     
         28 . A communications network as claimed in  claim 10 , further comprising an exception handling unit operable, in the event that a target transmission rate of said preselected signal when said change is effected, or a target transmission power of said preselected signal when that change is effected, is considered unachievable based on said measurement results, to inhibit said change from being made.  
     
     
         29 . A communications network as claimed in  claim 10 , further comprising an exception handling unit operable, in the event that a target transmission rate of said preselected signal when the change is effected, or a target transmission power of said preselected signal when that change is effected, is considered unachievable based on said measurement results, to cause said target transmission rate to be reduced and/or to cause said target transmission power to be increased so as to improve the prospect of successful transmission of said preselected signal when said change is effected.  
     
     
         30 . A communications network as claimed in  claim 10 , wherein said probing means unit is operable to set said one or more probing power levels in dependence upon power control commands transmitted from said second station to said first station for use by a power control unit of said first station to control a transmission power of signals sent from said first station to said second station.  
     
     
         31 . A communications network as claimed in  claim 30  wherein, in a probing period in which said probing signals are transmitted from said first station to said second station, said probing unit sets a target signal quality measure, representing a target signal quality of said probing signals as received at said second station, in dependence upon a target data rate of said preselected signal when said change is effected, and said second station produces its said power control commands in such a way as to tend to cause said probing signals to be transmitted from said first station at power levels which meet said target signal quality measure on reception at said second station.  
     
     
         32 . A communications network as claimed in  claim 10 , wherein at least one of said probing signals carries rate information for use by said second station in determining said transmission rate of said preselected signal when said change is effected, and said second station employs the carried rate information in measuring said results of transmission of said probing signals.  
     
     
         33 - 42 . (canceled)  
     
     
         43 . A base station, for use in a mobile communications network, comprising: 
 a probing unit operable, prior to a change in a transmission rate of a preselected signal transmitted from the base station to a user equipment of the network, to cause probing signals to be transmitted from the base station to said user equipment at one or more probing power levels.    
     
     
         44 . A base station as claimed in  claim 43 , wherein said user equipment measures results of transmission of said probing signals at said one or more power levels and transmits the measurement results to the base station, the base station further comprising: 
 a result employing unit arranged for receiving said measurement results from the user equipment and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of said predetermined signal and a transmission power thereof when the change is effected.    
     
     
         45 . A base station as claimed in  claim 43 , further comprising: 
 a result measurement unit for measuring results of transmission of said probing signals at said one or more power levels; and    a result employing unit arranged for receiving said measurement results and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of said predetermined signal and a transmission power thereof when the change is effected.    
     
     
         46 . A user equipment, for use in a mobile communications network having a transmitting station that is operable, prior to a change in a transmission rate of a preselected signal transmitted from that station to the user equipment, to cause probing signals to be transmitted from said other station to the user equipment at one or more probing power levels, the user equipment comprising: 
 a result measurement unit for measuring results of transmission of said probing signals at said one or more power levels; and    a result employing unit arranged for receiving said measurement results and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of said predetermined signal and a transmission power thereof when the change is effected.    
     
     
         47 . A user equipment, for use in a mobile communications network, comprising: 
 a probing meansunit operable, prior to a change in a transmission rate of a preselected signal transmitted from the user equipment to a receiving station of the network, to cause probing signals to be transmitted from the user equipment to said receiving station at one or more probing power levels.    
     
     
         48 . A user equipment as claimed in  claim 47 , wherein said receiving station measures results of transmission of said probing signals at said one or more power levels and transmits the measurement results to the user equipment, the user equipment further comprising: 
 a result employing unit arranged for receiving said measurement results from said receiving station and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of said predetermined signal and a transmission power thereof when the change is effected.    
     
     
         49 . A user equipment as claimed in  claim 47 , further comprising: 
 a result measurement unit for measuring results of transmission of said probing signals at said one or more power levels; and    a result employing unit arranged for receiving said measurement results and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of said predetermined signal and a transmission power thereof when the change is effected.    
     
     
         50 . A base station, for use in a mobile communications network having a user equipment that is operable, prior to a change in a transmission rate of a preselected signal transmitted from said user equipment to the base station, to cause probing signals to be transmitted from said user equipment to the base station at one or more probing power levels, the base station comprising: 
 a result measurement unit for measuring results of transmission of said probing signals at said one or more power levels; and    a result employing unit arranged for receiving said measurement results and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of said predetermined signal and a transmission power thereof when the change is effected.    
     
     
         51 . A communications method for use in a communications network comprising first and second stations, the first station comprising a transmitter and the second station comprising a receiver, wherein: 
 prior to a change in a transmission rate of a preselected signal from said first to said second station, probing signals are caused to be transmitted from said first station to said second station at one or more probing power levels;    results of transmission of said probing signals at said one or more power levels are measured; and    the measurement results are employed to provide information relating to a likely relationship between a transmission rate of said predetermined signal and a transmission power thereof when the change is effected.    
     
     
         52 . A communications network as claimed in  claim 10 , wherein said probing signals are transmitted using the same channel as is used to transmit said preselected signal.  
     
     
         53 . A communications network as claimed in  claim 10 , having respective first and second different channels available for transmission of signals from said first station to said second station, wherein said probing signals are transmitted using said first channel and said preselected signal is transmitted using said second channel.  
     
     
         54 . A communications network as claimed in  claim 10 , being a mobile communication network, one of the first and second stations being a base station of the mobile communications network and the other of the first and second station being a mobile station of the mobile communications network.  
     
     
         55 . A communications network as claimed in  claim 10 , being a mobile communications network, wherein each of the first and second stations is a user equipment of the mobile communications network.  
     
     
         56 . A mobile communications network as claimed in  claim 54 , wherein said first station is a base station of the network, said second station is one user equipment of the network, said first channel is a dedicated channel allocated individually to said one user equipment, and said second channel is a shared channel available for use on a shared basis by said one user equipment and by at least one further user equipment of the network.  
     
     
         57 . A mobile communications network as claimed in  claim 56 , wherein said network is a UTRA network, said first channel is a dedicated physical channel and said second channel is a physical downlink shared channel.  
     
     
         58 . A communications network as claimed in  claim 10 , wherein said preselected signal carries data in the form of packets.  
     
     
         59 . A communications network comprising first and second stations, said first station comprising a transmitter and said second station comprising a receiver, the network further comprising: 
 probing means operable, prior to a change in a transmission rate of a preselected signal from said first to said second station, to cause probing signals to be transmitted from said first station to said second station at one or more probing power levels and further operable to measure results of transmission of said probing signals at said one or more power levels and to employ the measurement results to provide information relating to a likely relationship between a transmission rate of said predetermined signal and a transmission power thereof when the change is effected.    
     
     
         60 . A base station, for use in a mobile communications network, comprising: 
 probing means operable, prior to a change in a transmission rate of a preselected signal transmitted from the base station to a user equipment of the network, to cause probing signals to be transmitted from the base station to said user equipment at one or more probing power levels.    
     
     
         61 . A user equipment, for use in a mobile communications network having a transmitting station that is operable, prior to a change in a transmission rate of a preselected signal transmitted from that station to the user equipment, to cause probing signals to be transmitted from said other station to the user equipment at one or more probing power levels, the user equipment comprising: 
 result measurement means for measuring results of transmission of said probing signals at said one or more power levels; and    result employing means arranged for receiving said measurement results and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of said predetermined signal and a transmission power thereof when the change is effected.    
     
     
         62 . A user equipment, for use in a mobile communications network, comprising: 
 probing means operable, prior to a change in a transmission rate of a preselected signal transmitted from the user equipment to a receiving station of the network, to cause probing signals to be transmitted from the user equipment to said receiving station at one or more probing power levels.    
     
     
         63 . A base station, for use in a mobile communications network having a user equipment that is operable, prior to a change in a transmission rate of a preselected signal transmitted from said user equipment to the base station, to cause probing signals to be transmitted from said user equipment to the base station at one or more probing power levels, the base station comprising: 
 result measurement means for measuring results of transmission of said probing signals at said one or more power levels; and    result employing means arranged for receiving said measurement results and operable to employ the measurement results to provide information relating to a likely relationship between a transmission rate of said predetermined signal and a transmission power thereof when the change is effected.