WPSK or WPA-PSK uses a pre-shared Key for authentication on a wireless system, so you don't need a Radius Server. All Wireless deviced would need to use the same pre-shared Key (PSK). Data transmitted is encrypted using a 64Bit, 128Bit or 256 Bit key derived from the PSK. This key changes regularly, providing greater protection. W/WPA is more secure than WEP, and is recommended for systems where no backward compatibilty is needed.