Communication network control system, radio communication apparatus, and communication network control method

A communication system including a radio base station and a plurality of radio terminals, said radio base station comprising:

• a monitor for detecting a congestion state in said communication system;
• and
• a transmitter for generating a signal indicating the congestion state to a radio terminal and transmitting said signal;
• and each of said radio terminals comprising:
• a receiver for receiving said signal, and
• a controller,
• said controller being configured to select a proper rate of CODEC of said radio terminal in accordance with the congestion state by analyzing the signal received from said radio base station, and
• said controller being configured to negotiate said selected rate with another radio terminal of said system as a speech communication partner.

A control method of a radio terminal in a communication system, said method comprising the steps of:

• receiving a signal indicating a congestion state in said communication system detected and generated by a radio base station of said system from the radio base station;
• selecting a proper rate of CODEC of said radio terminal in accordance with the congestion state by analyzing the signal received from said radio base station;
• and
• negotiating said selected rate with another radio terminal of said system as a speech communication partner.

A control method of a communication system including a radio base station and a plurality of radio terminals, said method comprising the steps of:

• detecting, at the radio base station, a congestion state in said communication system;
• generating, at the radio base station, a signal indicating the congestion state;
• sending, at the radio base station, said signal to a radio terminal;
• receiving at the radio terminal a signal indicating the congestion state detected by said radio base station;
• selecting, at said radio terminal, a proper rate of CODEC in accordance with the congestion state by analyzing the signal indicating the congestion state received from said radio base station;
• and
• negotiating, at said radio terminal, said selected rate with another radio terminal of said system as a speech communication partner.