Specification of Link Quality Degradation in WLAN based on MCS and Retransmission Flag

Wireless LAN is currently used in various cases such as homes and offices. However, if the carrier sense of each terminal is not detected, a hidden terminal problem appears in which packet collisions occur frequently, and the communication quality deteriorates significantly. In order to overcome the quality deterioration, it is usual to select the low coding rate and low order modulation scheme in the Modulation and Coding Scheme(MCS). However, for quality deterioration caused by packet collisions, there is a report that selecting a high coding rate and high-order modulation scheme shortens the packet length and suppresses the probability of packet collisions. The specifying scheme of causing the communication quality deterioration is necessary for suitable controlling MCS. In this paper, we propose a specifying scheme for communication quality deterioration that utilizes header information obtained by packet analysis in wireless LAN. The proposed method enables a third party to evaluate the quality of the wireless LAN by comparing the retransmission flag, which is the header information, with the MCS in each environment. In this research, we report that packet quality can be analyzed by using packet analysis in experimental evaluation, and the factor of quality deterioration according to the decrease in throughput with respect to quality can be determined.