Systems and methods for communicating to a disassociated station in a protected network

Abstract

Stations in standby mode in a wireless local area network (WLAN) become disassociated with their access point. In the event traffic is intended for the station in standby mode, a wakeup message needs to be communicated to the station. Typically, a wakeup message could be broadcast on a broadcast or multicast address, and when the station checks for broadcasts, the station can determine whether it needs to wake up. However, in a protected network, a disassociated station cannot decrypt messages from the access point without reassociating. However, the cost of reassociating in time and power can be significant, so reassociating should not be performed unless the station needs to wake up, leading to a vicious cycle as the station does not know it must wake up unless it can decrypt the message. To address this issue, in one embodiment the access points do not encrypt messages on a select multicast address, whereby messages such as wakeup message can be transmitted. In another embodiment, the messages are still encrypted. However, the identification of which station must wake up is encoded as the length of the encrypted payload. These methods allow a general message of communicating to disassociated stations in a protected WLAN environment.