Link adaptation method using feedback information for wireless communication system

A link margin adaptation method using feedback information of a wireless data communication system for transmission and reception of data between a first node and a second node of the wireless data communication system, comprising:

• transmitting a link margin information request message from the first node to the second node for the second node to estimate an SNR value between the first and second nodes by using the link margin information request message;
• comparing, at the second node, the SNR value with a predetermined SNR value designated in a white noise table to presume a link margin value;
• receiving, at the first node, a packet including the link margin value;
• estimating, at the first node, a delay spread value from the packet and comparing the delay spread value with a threshold value;
• using, at the first node, a delay spread table as a selected table when the delay spread value is greater than a threshold value, and using the white noise table as the selected table when the delay spread value is less than or identical to the threshold value;
• and
• adjusting, at the first node, a transmission rate and transmission power according to a current data transmission mode based on a relation between the link margin value and SNR values in the selected table,
• wherein the white noise table is a table including a first set of transmission rates and of corresponding SNRs that satisfy the first set of transmission rates in a white noise channel environment,
• wherein the delay spread table is a table including a second set of transmission rates and corresponding SNRs that satisfy the second set of transmission rates in a delay spread channel environment, and
• wherein the adjusting comprises:
• comparing a maximum SNR that supports a maximum transmission rate of the selected table with an estimated SNR estimated with the link margin value;
• and
• decreasing a transmission power until the estimated SNR corresponds to the maximum SNR, and setting a transmission rate between the first and second nodes to the maximum transmission rate of the selected table when the estimated SNR is higher than the maximum SNR.