Method and apparatus for establishing a communication link

A communication unit for operating in a communication system having a plurality of base sites coupled to a telephone network and capable of independently allocating a communication channel for use by the communication unit in response to a channel request signal transmitted from the communication unit in an attempt to gain allocation of the communication channel to communicate via the telephone network, and wherein a particular base site is an optimum base site in the sense that it is closer to the communication unit transmitting the channel request signal, the communication unit comprising:

• transmitter means;
• means for adjusting the transmitter means to transmit the channel request signal at variable power levels;
• receiving means for receiving channel grant signals from at least two of the plurality of base sites to provide received channel grant signals;
• means for measuring a value representing signal strength of each of the received channel grant signals;
• control means for increasing the variable power level of the transmitter means in response to the receiving means to transmit multiple channel request signals at the increasing variable power levels;
• and
• means for selecting the particular base site based on the values representing the signal strengths of the received channel grant signals.

In a communication system having a plurality of base sites for independently allocating a communication channel for use by a communication unit in response to a channel request signal from the communication unit, a method facilitating the use of a particular base site comprising the communication unit steps of:

• (a) transmitting a first channel request signal at a first power level;
• (b) receiving a first channel grant signal from a first base site of the plurality of base sites having a first signal strength level;
• (c) measuring and storing a first value representing the first signal strength level;
• (d) transmitting a second channel request signal at a second power level that is greater than the first power level;
• (e) receiving a second channel grant signal having a second signal strength level from a second base site of the plurality of base sites;
• (f) measuring and storing a second value representing the second signal strength level;
• (g) comparing the first value representing the first signal strength level with the second value representing the second signal strength level to determine which of the channel grant signals has a greater signal strength;
• and
• (h) selecting the particular base site based on the stored values representing the signal strength levels of the first and second base sites and on the first and second power levels.

A communication system, comprising:

• a telephone network;
• a plurality of base sites coupled to the telephone network and for independently allocating a communication channel for use by a communication unit in response to a channel request signal transmitted from the communication unit in an attempt to gain allocation of the communication channel to communicate via the telephone network, wherein a particular base site is an optimum base site in the sense that it is closer to the communication unit transmitting the channel request signal;
• and
• a plurality of communication units for communicating via the telephone network coupled to the base sites, wherein at least one of the communication units include:
• transmitter means;
• means for adjusting the transmitter means to transmit the channel request signal at variable power levels;
• receiving means for receiving channel grant signals from at least two of the plurality of base sites to provide received channel grant signals;
• means for measuring a value representing signal strength of each of the received channel grant signals;
• control means for increasing the variable power level of the transmitter means in response to the receiving means to transmit multiple channel request signals at the increasing variable power levels;
• and
• means for selecting the particular base site based on the values representing the signal strengths of the received channel grant signals.