Probing-Based Link Adaptation for High Data Rate Wireless LANs

We propose a probing-based link adaptation scheme that is incorporated into the aggregation with fragment retransmission (AFR) scheme for high data rate wireless LANs (WLANs). Thanks to the frame structure of multiple fragments in AFR, the proposed scheme can significantly reduce the probing overhead by transmitting a few fragments in a frame at a higher data rate. At the same time, it can easily estimate the fragment error rate in the MAC layer. To maximize the throughput and maintain the average fragment error rate below the target value, the data rate can be switched to a higher data rate based on the probing result or a more robust data rate based on the estimated fragment error rate. The proposed scheme does not need a calibration process, which is a major difficulty in implementing the exponential effective SNR mapping based fast link adaptation (FLA/EESM) scheme. Moreover, it is less affected by imperfect channel matrix estimation compared to the FLA/EESM scheme. In the performance evaluation for several channel models, the proposed scheme provides 3~10% and 5~15% more throughput than the FLA/EESM scheme with perfect and imperfect channel matrix estimations, respectively, while maintaining the average fragment error rate below the target value.