Method and apparatus for transmit power control in wireless data communication systems

A method for controlling the transmit power of a first Multi Band Orthogonal Frequency Division Multiplex (MB-OFDM) data transceiver, comprising:

• determining the distance between a first Multi Band Orthogonal Frequency Division Multiplex (MB-OFDM) data transceiver and a second or more such transceiver with which communication is to occur;
• determining the approximate radio frequency path loss PL expected given said distance between said transceivers;
• determining, by a known relationship between signal to noise ratio (SNR) and data rate, the approximate SNR desired for reliable reception of data at said known data rate;
• determining additional margin M desired for reliable communication at a desired FER, where M may include but is not limited to the sum of fading margin, implementation loss for the receiver, and other margins;
• determining the estimated modified transmit power level Pmod, which is that lowest level that allows successful reception and decoding of the data packet in a channel having noise power N, by summing said noise power N, said SNR, said margin M, said path loss PL, and said margin M;
• rounding said estimated modified transmit power level Pmod to the nearest achievable transmit power level;
• and
• using this rounded transmit power level as the initial starting power level for the known closed loop TPC process.

A method for controlling the transmit power of a first data transceiver, comprising:

• determining the distance between said first data transceiver and a second or more such transceiver with which communication is to occur;
• determining the approximate radio frequency path loss expected given said distance between transceivers;
• and
• adjusting the transmit power of said first data transceiver responsive to said path loss so as to transmit at a modified power level substantially as low as possible while still enabling reliable data communication, comprising:
• determining the distance D between a first Multi Band Orthogonal Frequency Division Multiplex (MB-OFDM) data transceiver and a second or more such transceiver with which communication is to occur;
• determining the data rate R(M) of the data to be transmitted;
• utilizing lookup table M from a multiplicity of lookup tables, determining the path loss PL(M) as a function of both distance D and data rate R(M), wherein the lookup table values are chosen to account also for fading margin, receiver implementation loss, other margin, and other factors such as LOS or NLOS conditions;
• adding PL(M) to a nominal transmit power level Pnom, where Pnom is typically that lowest power level known to facilitate reliable data communication at a nominal data rate, such as but not limited to the lowest data rate, and at a nominal distance, such as but not limited to the shortest distance;
• and
• transmitting data using this modified transmit power level Pmod.