Congestion Control Within A Radio Access Network

Abstract

A method of controlling the volume of user-plane traffic on the Iub or Iub/Iur interface between a Radio Network Controller and a Node B of a UMTS Radio Access Network during periods of overload. The method comprises, for individual uplink or downlink connections established over the Iub or Iub/Iur interface, monitoring at the Radio Network Controller the late arrival of frames at the Radio Network Controller or at the Node B transmitted over the Iub or Iub/Iur interface, and based on the results of said monitoring, causing a reduction in the Iub or Iub/Iur load for a connection when appropriate.

1 . A method of controlling the volume of user-plane traffic on the Iub or Iub/Iur interface between a Radio Network Controller and a Node B of a UMTS Radio Access Network during periods of overload, the method comprising, for individual uplink or downlink connections established over the Iub or Iub/Iur interface, monitoring at the Radio Network Controller the late arrival of frames at the Radio Network Controller or at the Node B transmitted over the Iub or Iub/Iur interface, and based on the results of said monitoring, causing a reduction in the Iub or Iub/Iur load for a connection when appropriate.  
     
     
         2 . A method according to  claim 1 , wherein the method is applied to packet switched connections over the Iub or Iub/Iur interface.  
     
     
         3 . A method according to  claim 1 , the step of monitoring the late arrival of frames comprises analysing results provided by a Frame Protocol entity.  
     
     
         4 . A method according to  claim 3 , wherein for the downlink direction said results are derived from TA-frames received at the Radio Network Controller from the NodeB and, in the uplink direction, the results are derived directly based upon the time of arrival of frames at the Radio Network Controller.  
     
     
         5 . A method according to  claim 1 , said step of monitoring the late arrival of frames comprising counting the number of TA-frames for the downlink direction, and/or late arriving frames in the uplink direction, and comparing the count value to some threshold value.  
     
     
         6 . A method according to  claim 5 , Iub or Iub/Iur load reduction being triggered when the count is equal to or exceeds the threshold value.  
     
     
         7 . A method according to  claim 1 , Iub or Iub/Iur load reduction being triggered based upon some defined probability following receipt of a TA-frame or the late arrival of a frame.  
     
     
         8 . A method according to  claim 1 , said step of monitoring the late arrival of frames comprising observing the time of arrival values contained in received TA-frames, or delays calculated for late arriving frames, and triggering Iub or Iub/Iur load reduction if the time of arrival or delay exceeds some defined threshold value.  
     
     
         9 . A method according to  claim 1 , said step of causing a reduction in the Iub or Iub/Iur load comprising restricting the allowed transport formats available to the sending Medium Access Control entity.  
     
     
         10 . A method according to  claim 1 , said step of causing a reduction in the Iub or Iub/Iur load comprising reducing the size of the Radio Link Control window.  
     
     
         11 . A method according to  claim 1 , said step of causing a reduction in the Iub or Iub/Iur load comprising switching the Radio Access Bearer to a state with a lower Iub resource consumption.  
     
     
         12 . A method according to  claim 1 , said step of causing a reduction in the Iub or Iub/Iur load comprising dropping IP packets queued for transmission over the congested Iub or Iub/Iur link.  
     
     
         13 . A method according to  claim 1 , said step of causing a reduction in the Iub or Iub/Iur load comprising discarding a fraction of the Iub user-plane frames in response to a TA frame or frames received at the radio network controller from a NodeB.  
     
     
         14 . A method according to  claim 1 , wherein said step of causing a reduction in the Iub or Iub/Iur load comprises requesting a reduction of the coding rate of a multi-rate speech encoder/decoder pair.  
     
     
         15 . A method of controlling the volume of user-plane traffic on the Iub or Iub/Iur interface between a Radio Network Controller and a Node B of a UMTS Radio Access Network during periods of overload, the method comprising, for individual uplink or downlink connections established over the Iub or Iub/Iur interface, monitoring at the Radio Network Controller or User Equipment the Radio Link Control retransmission rate or Radio Link Control throughput, and based on the results of said monitoring causing a reduction in the Iub Iub/Iur load for a connection when appropriate.  
     
     
         16 . A method of controlling the volume of user-plane traffic on the Iub or Iub/Iur interface between a Radio Network Controller and a Node B of a UMTS Radio Access Network during periods of overload, the method comprising, for individual downlink connections established over the Iub or Iub/Iur interface, monitoring at the Node B the late arrival of frames at the Node B transmitted over the Iub or Iub/Iur interface, and based on the results of said monitoring causing a reduction in the Iub or Iub/Iur load for a connection when appropriate.  
     
     
         17 . A method according to  claim 16 , said step of monitoring comprising comparing time stamps contained within received frames with a local clock.  
     
     
         18 . A method of controlling the volume of user-plane traffic on the Iub or Iub/Iur interface between a Radio Network Controller and a Node B of a UMTS Radio Access Network during periods of overload, the method comprising, for individual uplink or downlink connections established over the Iub or Iub/Iur interface, monitoring the late arrival of frames at the Radio Network Controller or at the Node B transmitted over the Iub or Iub/Iur interface, and based on the results of said monitoring, causing a reduction in the Iub or Iub/Iur load by restricting the allowed transport formats available to the sending Medium Access Control entity on a per connection basis.