Radio communication system

Abstract

A radio communication system has a random access channel for the transmission of data ( 214 ) from a secondary station to a primary station. Such a channel is intended for use by secondary stations having packets of data ( 214 ) to transmit to a primary station while not actually engaged in a call. A problem with known systems of this type is that a secondary station requesting access also specifies which of a plurality of channels it wishes to access. If that channel is busy access is denied, even if other suitable channels are available. In the present system the primary station transmits a random access channel availability (AV) message ( 302 ) once per frame to inform secondary stations about the resources currently available. Hence a secondary station can select a channel known to be free. If no channels are available the secondary station can avoid a wasted access attempt.

1 - 14 . (canceled) 
     
     
         15 . A secondary station, comprising:
 a receiver that is configured to receive a random access channel status message from a primary station, wherein the random access channel status message includes an indicated highest available data rate for each of a plurality of random access channels;   a controller that is configured to:
 select a selected random access channel from the plurality of random access channels, based on the indicated available data rates, and 
 create an access request for the selected random access channel; and 
   a transmitter that is configured to transmit the access request to the primary station.   
     
     
         16 . The secondary station of  claim 15 , wherein the random access channel status message is transmitted by the primary station as a part of a paging indicator channel. 
     
     
         17 . The secondary station of  claim 15 , wherein the random access channel status message is transmitted by the primary station as a part of an acquisition indicator channel. 
     
     
         18 . The secondary station of  claim 15 , wherein the indicated highest available data rate serves to identify whether a channel is available, and identifies a highest available data rate for available channels of the plurality of random access channels.