Radio communication system

摘要

A network has wireless access points, each configured for bi-directional communication, using a first radio protocol, with a communication device that has been associated with the access point by an association data exchange. Each access point is also configured to receive, at a first data rate using the first radio protocol, a multicast radio message and to forward the multicast message onto the network. A radio transmitter is configured to send data at a second data rate, using a second radio protocol different from the first radio protocol. A wireless communication unit transmits a multicast radio message at the first data rate using the first radio protocol. It also receives data from the radio transmitter at the second data rate using the second radio protocol and decodes the data.

主权项

1. A positioning system comprising:
a network of first access points and second access points, wherein:
each first access point is configured for bi-directional communication, using a first radio protocol, with a communication device that has been associated with the first access point by an association data exchange, wherein the first radio protocol conforms to, or is compatible with, one of the IEEE 802.11 standards;each first access point is further configured to receive, at a first data rate using the first radio protocol, a multicast radio message from a wireless communication unit that is not associated with the first access point, and to forward the message onto the network;each second access point is configured for two-way communication using a second radio protocol which is different from the first radio protocol; andeach second access point is configured to transmit data comprising control messages, addressed to one or more specific wireless communication units, at a second data rate which is lower than the first data rate, using the second radio protocol; a wireless communication unit:
comprising a radio transmitter configured to transmit a multicast radio message at the first data rate using the first radio protocol, wherein the multicast radio message comprises (i) identification information relating to the wireless communication unit, and (ii) information relating to the position of the wireless communication unit, or information from which the position of the wireless communication unit can be derived;comprising a radio receiver configured to receive and decode a control message from one of said second access points, received at the second data rate using the second radio protocol; andbeing configured to execute a function in response to receiving said control message; and a server configured to:
receive and process the multicast message from the wireless communication unit, forwarded to the server by one of the first access points, to determine the position of the wireless communication unit; andcontrol the sending of the control messages from the second access points.