I. Field
The present disclosure relates generally to extension of battery life in wireless communication systems, and more particularly to extension of battery lifetime in Bluetooth equipped wireless communication devices.
II. Background
Battery lifetime is a chief concern in portable Bluetooth 802.11 computing devices, such as Ultra Mobile Personal Computers (UMPCs) and Personal Digital Assistants (PDAs). It is known that battery lifetime can be extended by keeping the host processor asleep whenever possible. It is useful for such computer devices to be aware when they enter 802.11 coverage, and wake-up the host processor, if needed, thereby eliminating the need for the user to manually check for coverage.
In this connection, wake-up conditions must be sophisticated, varying from the existence of a network to complex conditions such as the existence of an urgent e-mail, availability of a particular kind of service, etc.
However, traditional wake-up solutions require the existence of alternative interfaces other than 802.11 to initiate wake-up, the presence of full-blown additional processors, or host processor hierarchies for wake-up initiation. Further, some solutions restricted to 802.11-based wake-ups are extremely inflexible (such as WoWLAN and AMD Magic packet). Moreover, traditional host processor wake-up conditions are not variable from application to application, which often change according to complex user requirements, such as the need to be notified of urgent e-mails, existence of a particular service, existence of a particular network and so forth. Current 802.11-initiated wake-up methods are very rigid and limiting.
U.S. Pat. No. 7,398,408 disclose methods for accessing computing devices over wireless local area networks and more particularly to systems and methods for waking computing devices from a powered down or sleep state with signals sent over wireless local area networks. This is accomplished by:
broadcasting a signal containing a wake-up data sequence for at least one computing device over a wireless network, wherein broadcasting the signal comprises periodically broadcasting the signal over one or more wireless channels until either a first predetermined time period expires or a confirmation signal is received;                receiving the broadcast signal at the at least one computing device, while that device is in a reduced power mode; wherein receiving comprises first entering a wake-up data sequence detection mode;        scanning the received signal for a wake-up data sequence for that computing device, wherein scanning is performed until either the wake-up data sequence for that computer device is received or a second predetermined time period expires; and        restoring that computing device to a full power mode upon detection of a wake-up data sequence for that device and exiting the wake-up data sequence detection mode if the second predetermined time period expires.        
There is a need for an infrastructure system where 802.11 ATs are only awake when interaction with the AP is needed and possible, and asleep (in standby) otherwise.
There is also a need to provide a flexible mechanism whereby the AT's 802.11 interface can detect when “interaction with the AP Is needed” as possible.