Method and apparatus for dynamic power control in TDMA portable radio systems

In a TDM/TDMA digital telephony system having a plurality of fixed ports and a plurality of mobile portable units, each port having a transmitter for transmitting burst signals in a plurality of time-slots at an associated downlink frequency to at least one portable unit and a receiver for receiving burst signals at an associated uplink frequency from at least one portable unit, each portable unit having a transmitter for transmitting burst signals at any one of a plurality of uplink frequencies to any one of said plurality of ports and a receiver for receiving burst signals at any one of a plurality of associated downlink frequencies from any one of said plurality of ports, a method for dynamically adjusting the uplink power of the signal transmitted by a portable to a port to which it is communicating comprising the steps of:

• determining a received signal strength indicator (RSSI) measure, a received signal quality measure (QM), and a word error indicator (WED from each uplink burst signal transmitted by the transmitter of a particular portable and received by the receiver at the port receiver with which the portable is communicating;
• adjusting an RSSI threshold upward and downward in accordance with the WEI determined in each burst;
• determining that additional uplink portable transmitter power is required if the QM is below a predetermined QM threshold or the RSSI is below the RSSI threshold, unless the RSSI is greater than a predetermined maximum RSSI value;
• or that reduced uplink portable transmitter power is required if both the QM is greater than the predetermined QM threshold and the RSSI is greater than the RSSI threshold, or if the RSSI is greater than the predetermined maximum RSSI value;
• transmitting in each downlink burst a power control bit that is set to ONE if it is determined that additional uplink portable transmitter power is required and is set to ZERO if it is determined that reduced uplink portable transmitter power is required;
• and
• adjusting the portable transmitter power upward if the portable receives from the port a burst with a power control bit of ONE and adjusting the portable transmitter power downward if the portable receives from the port a burst with a power control bit of ZERO.

In a TDM/TDMA digital telephony system having a plurality of fixed ports and a plurality of mobile portable units, each port having a transmitter for transmitting burst signals in a plurality of time-slots at an associated downlink frequency to at least one portable unit and a receiver for receiving burst signals at an associated uplink frequency from at least one portable unit, each portable unit having a transmitter for transmitting burst signals at any one of a plurality of uplink frequencies to any one of said plurality of ports and a receiver for receiving burst signals at any one of a plurality of associated downlink frequencies from any one of said plurality of ports, a method for dynamically adjusting the downlink power of the signal transmitted by a port to a portable to which it is communicating comprising the steps of:

• determining a received signal strength indicator (RSSI) measure, a received signal quality measure (QM), and a word error indicator (WEI) from each downlink burst signal transmitted by the transmitter of a particular port and received by the receiver at the portable receiver with which the port is communicating;
• adjusting an RSSI threshold upward and downward in accordance with the WEI determined in each burst;
• determining that additional downlink port transmitter power is required if the QM is below a predetermined QM threshold or the RSSI is below the RSSI threshold, unless the RSSI is greater than a predetermined maximum RSSI value;
• or that reduced downlink port transmitter power is required if both the QM is greater than the predetermined QM threshold and the RSSI is greater than the RSSI threshold, or if the RSSI is greater than the predetermined maximum RSSI value;
• transmitting in each uplink burst a power control bit that is set to ONE if it is determined that additional downlink port transmitter power is required and is set to ZERO if it is determined that reduced downlink port transmitter power is required;
• and
• adjusting the port transmitter power upward if the port receives from the portable a burst with a power control bit of ONE and adjusting the port transmitter power downward if the port receives from the portable a burst with a power control bit of ZERO.

In a TDM/TDMA digital telephony system having a plurality of fixed ports and a plurality of mobile portable units, each port having a transmitter for transmitting burst signals in a plurality of time-slots at an associated downlink frequency to at least one portable unit and a receiver for receiving burst signals at an associated uplink frequency from at least one portable unit, each portable unit having a transmitter for transmitting burst signals at any one of a plurality of uplink frequencies to any one of said plurality of ports and a receiver for receiving burst signals at any one of a plurality of associated downlink frequencies from any one of said plurality of ports, apparatus for dynamically adjusting the uplink power of the signal transmitted by a portable to a port to which it is communicating comprising at a port:

• determining means for determining a received signal strength indicator (RSSI) measure, a received signal quality measure (QM), and a word error indicator (WEI) from each uplink burst signal transmitted by the transmitter of a particular portable and received by the receiver at the port receiver with which the portable is communicating;
• threshold adjusting means for adjusting an RSSI threshold upward and downward in accordance with the WEI determined in each burst;
• power control means for determining that additional uplink portable transmitter power is required if the QM is below a predetermined QM threshold or the RSSI is below the RSSI threshold, unless the RSSI is greater than a predetermined maximum RSSI value;
• transmitting means for transmitting in each downlink burst a power control signal request for additional uplink portable transmitter power if said means for determining determines that additional uplink portable transmitter power is required;
• and at the portable:
• power adjusting means for adjusting the uplink portable transmitter power upward if the portable receiver receives a burst including a power control signal request from the port transmitter for additional transmitter power.

In a TDM/TDMA digital telephony system having a plurality of fixed ports and a plurality of mobile portable units, each port having a transmitter for transmitting burst signals in a plurality of time-slots at an associated downlink frequency to at least one portable unit and a receiver for receiving burst signals at an associated uplink frequency from at least one portable unit, each portable unit having a transmitter for transmitting burst signals at any one of a plurality of uplink frequencies to any one of said plurality of ports and a receiver for receiving burst signals at any one of a plurality of associated downlink frequencies from any one of said plurality of ports, apparatus for dynamically adjusting the downlink power of the signal transmitted by a port to a portable to which it is communicating comprising at a portable:

• determining means for determining a received signal strength indicator (RSSI) measure, a received signal quality measure (QM), and a word error indicator (WEI) from each downlink burst signal transmitted by the transmitter of a particular port and received by the receiver at the portable receiver with which the port is communicating;
• threshold adjusting means for adjusting an RSSI threshold upward and downward in accordance with the WEI determined in each burst;
• power control means for determining that additional downlink port transmitter power is required if the QM is below a predetermined QM threshold or the RSSI is below the RSSI threshold, unless the RSSI is greater than a predetermined maximum RSSI value;
• transmitting means for transmitting in each uplink burst a power control signal request for additional downlink port transmitter power if said means for determining determines that additional downlink port transmitter power is required;
• and at the port:
• power adjusting means for adjusting the downlink port transmitter power upward if the port receiver receives a burst including a power control signal request from the portable transmitter for additional transmitter power.