Revisiting the impact of encryption on performance of IEEE 802.11 WLAN

A misperception that encryption largely degrades performance of the system may have discouraged many IEEE 802.11 WLAN infrastructures from enabling wireless signal encryption. In particular, there have been several recent research studies suggesting that encryption could noticeably degrade performance of WLAN systems by as much as 20%. Since the 2.4 GHz frequency spectrum used in the IEEE 802.11 WLAN systems is unlicensed and shared by various kinds of wireless devices and appliances, the high interference in this frequency band may affect the experiment results. Hence, it is worthwhile to reinvestigate and verify whether encryption in WLANs actually introduces that much performance degradation. In essence, encryption should only have minimal impact on performance because the amount of overhead inserted by the encryption algorithms is normally less than 1% of the total payload. In this work, we reinvestigate the issue of the impact of encryption on the throughput performance of WLANs. We present the analysis and experiment results to demonstrate that encryption actually has negligible impact on the throughput performance of a WLAN system regardless of the MAC payload size the system uses, regardless of whether the system uses UDP or TCP, and regardless of whether the system operates in the infrastructure topology or the peer-to-peer topology.