US Patent 8064601 Security in wireless communication systems

Wireless security is enforced at L1, in addition to or in lieu of other layers. AP's can switch dynamically from serving to scanning. Scanners listen for authorized frame headers. Scanners either receive, or allow authorized frames to be received, at their destination. Scanners kill unauthorized frames while they are still transmitting; scanners continue listening for and killing unauthorized frame headers until frame ending time demands their return to serving, multiplying their effectiveness. AP's include dual-mode multi-frequency omni-directional antennae, used to prevent third parties from snooping messages received at those AP's.