Due to the lack of security in IEEE 802.11b, IEEE 802.11i that can provide strong security is proposed. However, most users use WLAN (Wireless Local Area Networks) to do web-surfing so that IEEE 802.11i has needless delays and computational overheads. And even though the node authentication is performed in wireless domain between Station (STA) and Access Point (AP) in IEEE 802.11, the malicious node can masquerade itself as if the authenticated STA, and then it can transmit packets to the AP. Although TKIP (Temporal Key Integrity Protocol) and CCMP (CTR with CBC-MAC Protocol) are used in IEEE 802.11i, they have needless features for device with limited ability. Therefore, in this paper, the Lightweight Packet Authentication (UFA) is proposed and whose performance is compared with those of TKIP and CCMP.