Wireless data communication system having power saving function

A wireless data communication system, comprising:

• a selected wireless data communication station having a synchronizing timing means adapted to control transmission of synchronizing messages by said selected station;
• means for transmitting traffic indicator information, in association with the synchronizing messages, that identify data message destinations;
• a number of non-selected wireless data communication stations each having a switching means, a power supply, and a station transceiver means, wherein the switching means is adapted to control the power supply which is applied to the station transceiver means so that the non-selected stations are controlled to be in an awake state of relatively high power consumption to receive the synchronizing messages and the traffic indicator messages, and following receipt of the synchronizing messages and the traffic indicator information (1) any non-selected stations having no data messages destined therefor are changed to a doze state of relatively low power consumption, and (2) all non-selected stations having data messages destined therefor are maintained in the awake state for a time period beginning immediately after receiving the synchronizing messages and the traffic indicator messages;
• wherein said selected station is an access point communicating with a backbone LAN, and further wherein the synchronizing messages include destination identifying portions identifying stations that are to receive data messages;
• and
• wherein the synchronizing messages include count information identifying the number of data messages to be transmitted to the respective non-selected stations, and further wherein the switching means is controlled to return the respective non-selective stations to the doze state when the specified number of data messages have been received.

A method of operating a wireless data communication system including a plurality of wireless data communication stations communicating directly in an ad-hoc network, wherein at least one of the plurality of wireless data communication stations acts as a master station and the remainder of the plurality of wireless data communication stations act as slave stations, said method comprising:

• broadcasting a synchronizing message by the master station in accordance with a synchronization timer, wherein the slave stations remain in an awake state;
• entering a doze state by the slave stations once the synchronizing message from the master station is received;
• transmitting a traffic message by a slave station that has messages to broadcast, if the slave station is in the awake state;
• wherein the traffic message is stored in a buffer of the slave station that has messages to broadcast and the traffic message is transmitted to all stations to which the slave station wishes to transmit, wherein a holdover timer ensures the slave station remains in the awake state until all the message are broadcast.

A wireless data communication system including a plurality of wireless data communication stations communicating directly in an ad-hoc network, wherein at least one of the plurality of wireless data communication stations acts as a master station and the remainder of the plurality of wireless data communication stations act as slave stations, wherein said system:

• said master station broadcasts a synchronizing message in accordance with a synchronization timer, wherein the slave stations remain in an awake state;
• said slave stations enter a doze state once the synchronizing message from the master station is received;
• a slave station that has messages to broadcast transmits a traffic message, if the slave station is in the awake state;
• wherein the traffic message is stored in a buffer of the slave station that has messages to broadcast and the traffic message is transmitted to all stations to which the slave station wishes to transmit, wherein a holdover timer ensures the slave station remains in the awake state until all the message are broadcast.