Patent ID: 6728259
Filing Date: 2004-04-27
Classification: H04L

Abstract:
A method for operating a channel coder, comprising steps of:maintaining a first count (N_Number) of transmitted packets and a second count (K_Number) of packets that are erroneously decoded at a receiver; periodically performing a plurality of statistical tests using current values of the first and second counts; and based on a result of said statistical tests, controlling said channel coder to either maintain a current channel coding technique or to switch to another channel coding technique, wherein the step of periodically performing a plurality of statistical tests is comprised of steps: at a crossing point where a first channel coding algorithm (CS-1) and a second channel coding algorithm (CS-2) provide a same net bit rate, making a first assumption that a packet error rate (PER) is greater than a PER of CS-1 at the crossing point, P1, when CS-1 is currently being used, or making as the first assumption that the PER is less than a PER of CS-2 at the crossing point, P2, when CS-2 is currently being used; making as a further assumption, as reference case, that N_Number of packets have been transmitted with a constant PER equal to either P1 or P2, depending on the currently used channel coding algorithm CS-1 or CS-2; determining a first probability (P-value) using said first count and said second count and the constant PER P1 or P2, depending on the currently used channel coding algorithm CS-1 or CS-2; comparing P-value to a risk level (RL) for determining whether the first assumption can be rejected; and when the first assumption is rejected, changing to the other channel coding algorithm and resetting N_Number and K_Number; making a second assumption that PER is less than the PER of CS-1, P1, when CS-1 is currently being used, or making as the second assumption that PER is greater than the PER of CS-2, P2, when CS-2 is currently being used; making as the same further assumption, the same reference case, that N_Number of packets have been transmitted with a constant PER equal to either P1 or P2, depending on the currently used channel coding algorithm CS-1 or CS-2; determining a second probability (P-value) using said first count and said second count and the constant PER P1 or P2, depending on the currently used channel coding algorithm CS-1 or CS-2; comparing P-value to RL for determining whether the second hypothesis can be rejected; and when the second assumption is rejected, resetting N_Number and K_Number without changing to the other channel coding algorithm.