Monitoring Network Conditions

Abstract

A method of identifying a network condition between a pair of network devices, wherein one of the devices comprises a jitter buffer for storing packets received via a network, the method comprising: monitoring a measure of delay in receiving media packets over the network; monitoring a size of the jitter buffer; and identifying a network condition in dependence on a change in the measure of delay and a variation in the size of the jitter buffer.

What is claimed is: 
     
         1 . A method of identifying a network condition between a receiving device and a transmitting device, wherein the receiving device comprises a jitter buffer for storing packets received from the transmitting device via a network, the method comprising:
 monitoring, over a period of time, a variation in a measure of delay in receiving media packets over the network;   monitoring, over the period of time, a variation in a size of the jitter buffer; and   identifying a network condition by monitoring, over the period of time, for a scenario indicative of that network condition in which:
 the measure of delay is increasing, remaining substantially constant and/or decreasing; and 
 contemporaneously, the size of the jitter buffer is increasing, remaining substantially constant and/or decreasing. 
   
     
     
         2 . The method as claimed in  claim 1 , wherein the identifying step comprises identifying a decrease in network delay in response to determining that, over the period of time:
 (i) the measure of delay decreases and subsequently remains substantially constant; and   (ii) the size of the jitter buffer increases above a threshold size and subsequently decreases below the threshold size whilst the measure of delay remains substantially constant.   
     
     
         3 . The method as claimed in  claim 2 , wherein the threshold size is determined in dependence on a target jitter buffer size of the jitter buffer comprised by the receiving device. 
     
     
         4 . The method as claimed in  claim 2 , wherein the identifying step further comprises identifying that the decrease in network delay is caused by a change in the network route between the transmitting device and the receiving device. 
     
     
         5 . The method as claimed in  claim 1 , wherein the identifying step comprises identifying burstiness in response to determining that, over the period of time:
 (i) the size of the jitter buffer decreases below a lower threshold size;   (ii) subsequently to (i), the measure of delay and the size of the jitter buffer both increase, wherein the size of the jitter buffer increases above an upper threshold size; and   (iii) subsequently to (ii), the size of the jitter buffer decreases below the upper threshold size whilst the measure of delay remains substantially constant.   
     
     
         6 . The method as claimed in  claim 5 , wherein the identifying step comprises identifying burstiness in response to determining that, over the period of time:
 (ii), subsequently to (i), the measure of delay and the size of the jitter buffer contemporaneously increase, wherein the size of the jitter buffer increases above an upper threshold size.   
     
     
         7 . The method as claimed in  claim 5 , wherein the upper threshold size and the lower threshold size are determined in dependence on a target jitter buffer size of the jitter buffer comprised by the receiving device. 
     
     
         8 . The method as claimed in  claim 1 , wherein the identifying step comprises identifying congestion in the network in response to determining that, over the period of time:
 (i) the measure of delay increases; and   (ii) the size of the jitter buffer decreases.   
     
     
         9 . The method as claimed in  claim 8 , wherein the identifying step comprises identifying congestion in the network in response to determining that, over the period of time:
 (ii) the size of the jitter buffer decreases below a threshold size.   
     
     
         10 . The method as claimed in  claim 9 , wherein the threshold size is determined in dependence on a target jitter buffer size of the jitter buffer comprised by the receiving device. 
     
     
         11 . The method as claimed in  claim 8 , wherein the identifying step comprises identifying congestion in the network in response to further determining that, over the period of time, the gradient of the decrease in the size of jitter buffer is proportional to the gradient of the increase in the measure of delay. 
     
     
         12 . The method as claimed in  claim 1 , wherein the identifying step comprises identifying an increase in network delay in response to determining that, over the period of time:
 (i) the measure of delay increases and subsequently remains substantially constant; and   (ii) the size of the jitter buffer decreases below a threshold size and subsequently increases above the threshold size whilst the measure of delay remains substantially constant.   
     
     
         13 . The method as claimed in  claim 12 , wherein the threshold size is determined in dependence on a target jitter buffer size of the jitter buffer comprised by the receiving device. 
     
     
         14 . The method as claimed in  claim 12 , wherein the identifying step further comprises identifying that the increase in network delay is caused by a change in the network route between the transmitting device and the receiving device. 
     
     
         15 . The method as claimed in  claim 12 , the method further comprising, prior to using the measure of delay for other purposes, adjusting the measure of delay in dependence on a calculated bias. 
     
     
         16 . The method as claimed in  claim 1 , the method further comprising adjusting a transmission parameter of the transmitting device in dependence on the identified network condition. 
     
     
         17 . The method as claimed in  claim 16 , the method comprising adjusting a bandwidth for transmission of media by the transmitting device in dependence on the identified network condition. 
     
     
         18 . The method as claimed in  claim 1 , the method further comprising adjusting a reception parameter of the receiving device in dependence on the identified network condition. 
     
     
         19 . The method as claimed in  claim 18 , the method comprising adjusting a target jitter buffer size of the jitter buffer comprised by the receiving device in dependence on the identified network condition. 
     
     
         20 . A receiving device configured to receive a stream of media packets via a network, the receiving device comprising:
 a jitter buffer configured to store media packets received from a transmitting device via the network; and   a controller configured to:
 monitor, over a period of time, a variation in a measure of delay in receiving the media packets over the network; 
 monitor, over the period of time, a variation in a size of the jitter buffer; and 
 identify a network condition by monitoring, over the period of time, for a scenario indicative of that network condition in which:
 the measure of delay is increasing, remaining substantially constant and/or decreasing; and 
 contemporaneously, the size of the jitter buffer is increasing, remaining substantially constant and/or decreasing.