Method of optimizing the transmission of idle beacon messages and a communications system using the method

A communications system comprising a primary station and at least one transportable secondary station which communicates with the primary station over a radio link on one of a plurality of channels, the primary station and each secondary station each including a respective transceiver for establishing a radio link on one of said channels, and each transceiver comprising means for scanning said plurality of channels and means for monitoring each respective level of interference,

• wherein said primary station comprises means for controlling its transceiver to transmit paging signals, and to transmit normal idle beacon transmissions at a normal rate of repetition when the primary station has no radio link established with any secondary station,
• characterized in that said primary station further comprises
• means for monitoring the traffic history in said channels,
• means for determining the time elapsed since said primary station last established a link with a secondary station, and
• means, responsive to said primary station's detecting the conditions that said station has not had a radio link established with any secondary station for the duration of a predetermined time interval, and that the primary station's level of interference does not exceed a given level, for transmitting a low duty cycle request message as a paging signal.

A primary station for use in a communications system comprising at least one transportable secondary station which communicates with the primary station over a radio link on one of a plurality of channels, the primary station including a transceiver for establishing a radio link on one of said channels, said transceiver comprising means for scanning said plurality of channels and means for monitoring the primary station's level of interference,

• wherein said primary station comprises means for controlling its transceiver to transmit paging signals, and a control element for controlling the primary station to transmit normal idle beacon transmissions at a normal rate of repetition when the primary station has no radio link established with any secondary station,
• characterized in that said control element further comprises
• means for monitoring the traffic history in said channels,
• means for determining the time elapsed since said primary station last established a link with a secondary station, and
• means, responsive to said primary station's detecting the conditions that said station has not had a radio link established with any secondary station for the duration of a predetermined time interval, and that the level of interference does not exceed a given level, for transmitting a low duty cycle request message as a paging signal.