Method and apparatus for communication system access

A method of controlling access to a communication resource comprising:

• (a) determining from system parameters a first access value for a first group of communication units and a second access value for a second group of communication units, the first group having a higher priority for communication than the second group;
• and
• (b) transmitting an access control message including the first and second access values, wherein step (a) further comprises:
• (i) determining an approximate number v of ready communication units of both first and second groups;
• (ii) determining a first access probability p.sub.1 for the first group based on the approximate number v of ready communication units, a proportion .alpha. of access requests by the first group to a total number of access requests by the first and second groups during a predetermined period, and an approximate maximum channel throughput value .beta., such that p.sub.1 =(1+.alpha.)(.beta./v);
• and
• (iii) determining a second access probability p.sub.2 for the second group based on v, .alpha. and .beta. such that p.sub.2 =.alpha..beta./v.

A method of accessing a communication resource of a base station comprising, at a first communication unit:

• (a) receiving an access control message for the communication resource including a first persistence value for a first group of communication units and a second persistence value for a second group of communication units, the first group having a higher priority for access to the communication resource than the second group;
• (b) selecting one of the first and second persistence values based on which one of the first and second groups the first communication unit is currently a member;
• and
• (c) determining a probability of sending an access message using said one of the first and second persistence values selected in step (b), and then sending the access message with a determined probability on the communication resource.

A method of accessing a communication resource of a base station comprising at a first communication unit:

• (a) receiving an access control message for the communication resource including a first access value for a first group of communication units and a second access value for a second group of communication units, the first group having a higher priority for access to the communication resource than the second group;
• (b) selecting one of the first and second access values based on which one of the first and second groups the first communication unit is currently a member;
• and
• (c) determining a probability of sending an access message using said one of the first and second access values selected in step (b), and then sending the access message on the communication resource with a determined probability, wherein the access control message includes an inhibit message for the second group, and step (c) further comprises inhibiting the access message in response to the inhibit message.

A method of accessing a communication resource of a base station comprising, at a first communication unit:

• (a) receiving an access control message for the communication resource including a first access value for a first group of communication units and a second access value for a second group of communication units, the first group having a higher priority for access to the communication resource than the second group;
• (b) selecting one of the first and second access values based on which one of the first and second groups the first communication unit is currently a member;
• and
• (c) determining a probability of sending an access message using said one of the first and second access values selected in step (b), and then sending the access message on the communication resource with a determined probability, wherein the access control message includes an indication that in a current period of plural access periods access messages from the second group are to be inhibited, step (c) further comprising inhibiting the access message in response to the access control message when the first communication unit is one of the second group of communication units.

A communication system having a communication resource for use in accessing the communication system, comprising:

• a base station transceiver adapted for communication to plural communication units;
• a controller in communication with the transceiver operable for determining from system parameters a first persistence value for a first group of the communication units and a second persistence value for a second group of the communication units, the first group having a higher priority for access to the communication resource than the second group;
• and
• wherein the base station transceiver is responsive to the controller to transmit an access control message including the first and second persistence values.