entail transmitting packets at different signal levels and detecting pdr in fig7 b three portions may be defined by the curve 702 a loss region 706 a receipt region 714 and a u201c grey u201d region 710 in this example the loss region 706 may be defined as a region with an snr corresponding to a pdr less than some threshold 708 which is too low for use in effective communication for example the threshold may be 10 receipt region 714 may be defined as a region with a pdr greater than a threshold 712 which may be for example 90 the u201c grey u201d region 710 may be defined as a region between the loss region 706 and the receipt region 714 the snr at the boundary between the loss region 706 and grey region 710 may be defined as snr low and the snr at the boundary between grey region 710 and receipt region 714 may be defined as snr high as shown in fig7 b snr low is associated with the threshold 716 and snr high is associated with the threshold 718 to determine the thresholds 716 and 718 for a transmitted data rate only measurements of the snr in the area where the pdr is about 10 and about 90 respectively are taken as shown by respective crosses and circles as can be seen substantially fewer measurements are required to determine snr low and snr high than would be required to fully determine the shape of curve 702 in the embodiment illustrated the snr low threshold may be set to the smallest snr corresponding to a pdr of about 10 transmitted data rate by way.