Patent ID: 8102939
Filing Date: 2012-01-24
Classification: H04L,Y02D

Abstract:
1. An adaptation method comprising steps of: using a selecting unit in a transmitting node of a data communication system operating under Institute of Electrical and Electronics Engineers (IEEE) section 802.11, in a time-varying channel, to adapt a variable transmission data rate in a transmitting node of a data communication system to a current link quality of a data communication channel, wherein said variable transmission data rate is selected by the transmitting node from a set of transmission data rates; wherein the selecting unit employs only information available at the transmitting node to determine whether an actual link quality is improving or worsening, the adapting comprising in the transmitting node the steps of: setting a threshold value of one for faulty transmissions; setting a minimum threshold value of three for successful transmissions in the time-varying channels; setting a maximum threshold value of ten for successful transmissions in the time-varying channels; operating in a first state in response to detecting at least the minimum threshold value but less than the maximum threshold value for successful transmissions from a receiving node, wherein the first state corresponds to a link with fast changing quality; operating in a second state in response to detecting the maximum threshold value for successful transmissions from the receiving node, wherein the second state corresponds to a link with slow changing quality; transitioning to the first state when detecting a faulty transmission while operating in the second state; selecting an adapted data transmission rate by: comparing a data transmission rate used by the receiving node to a current data transmission rate when the successful transmission is detected; selecting a new packet length different from an original packet length being used when the data transmission rate used by the receiving node is not higher than the current data transmission rate; and selecting the data transmission rate used by the receiving node in the successful transmission if that data transmission rate is higher than the current data transmission rate; incrementing a first counter for each successful transmission; resetting the first counter to zero when a transmission fails; and in dependence of a result of a following transmission causing the method to operate in the first state or the second state.