Methods and apparatus of power control in wireless communication systems

A communications method for use in an orthogonal frequency division multiplexed system, the method comprising:

• modulating first control information on a single tone to generate a first control signal;
• and
• transmitting said first control signal using said single tone during a single orthogonal frequency division multiplexed symbol transmission time period;
• wherein said first control information is transmission power control information corresponding to a first wireless terminal;
• wherein said first control signal includes an In-phase component and a Quadrature component, said first control information being modulated on a first single one of said In-phase and Quadrature components;
• wherein said modulating includes performing amplitude modulation, the method further comprising:
• multiplying the amplitude modulated one of the In-phase and Quadrature components by a first scaling factor, said first scaling factor being a function of downlink quality report information so far received from the wireless terminal to which the modulated one of the In-phase and Quadrature components corresponds;
• and
• increasing said first scaling factor in response to receiving downlink quality information indicative of a decrease in downlink channel quality and decreasing said first scaling factor in response to receiving downlink quality information indicative of a increase in downlink channel quality.

A communications method for use in an orthogonal frequency division multiplexed system, the method comprising:

• modulating first control information on a single tone to generate a first control signal;
• transmitting said first control signal using said single tone during a single orthogonal frequency division multiplexed symbol transmission time period;
• wherein said first control information is transmission power control information corresponding to a first wireless terminal,
• the method further comprising:
• periodically transmitting a first set of said modulated power control signals corresponding to a first wireless terminal, at least some of said first set of modulated power control signals being modulated on different tones during different orthogonal frequency division multiplexed symbol transmission time periods;
• wherein the tones used to modulate said first set of modulated power control signals is determined by a first predetermined hopping sequence;
• and
• wherein said first wireless terminal uses a second predetermined hopping sequence to select tones for data communication purposes, the periodicity of the second predetermined hopping sequence being shorter than the periodicity of the first predetermined hopping sequence.

A communications method for use in an orthogonal frequency division multiplexed system, the method comprising:

• modulating first control information on a single tone to generate a first control signal;
• and
• transmitting said first control signal using said single tone during a single orthogonal frequency division multiplexed symbol transmission time period;
• wherein said first control information is transmission power control information corresponding to a first wireless terminal;
• wherein said first control signal includes an In-phase component and a Quadrature component, said first control information being modulated on a first single one of said In-phase and Quadrature components, the method further comprising:
• transmitting a plurality of power control signals to said first wireless terminal over a period of time;
• and
• transmitting a periodic device identifier signal on the second single one of the In-phase and Quadrature signal components of at least 50% less frequently than the power control signals transmitted to said first wireless terminal;
• and
• wherein said single orthogonal frequency division multiplexed symbol transmission time period during which said periodic device identifier is transmitted is a function of a wireless device identifier unique to said first wireless terminal.

A communications apparatus for use in an orthogonal frequency division multiplexed communications system including a wireless terminal, the communications apparatus comprising:

• a modulator for modulating first control information on a single tone to generate a first control signal;
• and
• a transmitter coupled to said modulator for transmitting said first control signal using said single tone during a single orthogonal frequency division multiplexed symbol transmission time period;
• wherein said first control information is one of transmission power control information, transmission frequency control information, and transmission timing control information corresponding to said wireless terminal;
• wherein said first control signal includes an In-phase component and a Quadrature component;
• wherein said modulator is an amplitude modulator for amplitude modulating first control information on a first single one of said In-phase and Quadrature components, the apparatus further comprising:
• a scaling device for multiplying the amplitude modulated one of the In-phase and Quadrature components by a first scaling factor, said first scaling factor being a function of downlink quality report information so far received from the wireless terminal to which the modulated one of the In-phase and Quadrature components corresponds;
• means for increasing said first scaling factor in response to receiving downlink quality information indicative of a decrease in downlink channel quality and decreasing said first scaling factor in response to receiving downlink quality information indicative of a increase in downlink channel quality.

A communications apparatus for use in an orthogonal frequency division multiplexed communications system including a wireless terminal, the apparatus comprising:

• a modulator for modulating first control information on a single tone to generate a first control signal;
• and
• a transmitter coupled to said modulator for transmitting said first control signal using said single tone during a single orthogonal frequency division multiplexed symbol transmission time period;
• wherein said first control information is one of transmission power control information, transmission frequency control information, and transmission timing control information corresponding to said wireless terminal;
• a tone allocation module for allocating tones used to transmit power control signals according to a first predetermined frequency hopping pattern said tones assigned according to the first frequency hopping pattern including a first set of modulated power control signals, at least some of said first set of modulated power control signals being modulated on different tones during different orthogonal frequency division multiplexed symbol transmission time periods;
• wherein said first control signal includes an In-phase component and a Quadrature component;
• wherein said modulator is an amplitude modulator for amplitude modulating first control information on a first single one of said In-phase and Quadrature components;
• and
• wherein tones are allocated for transmitting data to said wireless terminal according to a second predetermined hopping sequence, the periodicity of the second predetermined hopping sequence being shorter than the periodicity of the first predetermined hopping sequence.

A communications apparatus for use in an orthogonal frequency division multiplexed communications system including a wireless terminal, the apparatus comprising:

• a modulator for modulating first control information on a single tone to generate a first control signal;
• and
• a transmitter coupled to said modulator for transmitting said first control signal using said single tone during a single orthogonal frequency division multiplexed symbol transmission time period;
• wherein said first control information is one of transmission power control information, transmission frequency control information, and transmission timing control information corresponding to said wireless terminal;
• wherein said first control signal includes an In-phase component and a Quadrature component;
• wherein said modulator is an amplitude modulator for amplitude modulating first control information on a first single one of said In-phase and Quadrature components;
• wherein said transmitter transmits a plurality of power control signals to said first wireless terminal over a period of time;
• and includes means for transmitting a periodic device identifier signal on the second single one of the In-phase and Quadrature signal components on less than 50% of the power control signals transmitted to said wireless terminal;
• and
• wherein said single orthogonal frequency division multiplexed symbol transmission time period during which said periodic device identifier is transmitted is a function of a wireless device identifier unique to said wireless terminal.

A communications apparatus for use in an orthogonal frequency division multiplexed communications system including a wireless terminal, the apparatus comprising:

• a modulator for modulating first control information a single tone to generate a first control signal;
• and
• a transmitter coupled to said modulator for transmitting said first control signal using said single tone during a single orthogonal frequency division multiplexed symbol transmission time period;
• wherein said first control information is one of transmission power control information, transmission frequency control information, and transmission timing control information corresponding to said wireless terminal;
• wherein said first control signal includes an In-phase component and a Quadrature component;
• wherein said modulator is an amplitude modulator for amplitude modulating first control information on a first single one of said In-phase and Quadrature components;
• wherein said transmitter transmits a plurality of power control signals to said first wireless terminal over a period of time;
• and includes means for transmitting a periodic device identifier signal on the second single one of the In-phase and Quadrature signal components on less than 50% of the power control signals transmitted to said wireless terminal;
• and
• wherein the value of the periodic device identifier at any given time is a function of a wireless device identifier unique to said first wireless terminal.

A method of operating a wireless terminal in an orthogonal frequency division multiplexed communications system, the method comprising:

• periodically receiving control signals corresponding to said wireless terminal, each control signal having control information of a first type, corresponding to one of at least three different values, said control signal being received on a first single one of an In-phase component and a Quadrature phase component of a single tone during a single orthogonal frequency division multiplexed symbol transmission time period;
• determining from said first single one of said In-phase and Quadrature phase signal components of each received control signal an adjustment to be made, said adjustment corresponding to the control information type;
• checking a signal transmitted on a second single one of the In-phase and Quadrature phase components to determine if said single orthogonal frequency division multiplexed symbol transmission time period during which said signal is transmitted and the value of said signal are a function of a wireless device identifier unique to said wireless terminal;
• and
• wherein said first type of information is one of power control information, timing control information and frequency control information.

A wireless terminal for use in an orthogonal frequency division multiplexed communications system, the wireless terminal comprising:

• means for receiving control signals corresponding to said wireless terminal, each control signal having control information of a first type, corresponding to one of at least three different values, amplitude modulated on a first single one of an In-phase component and a Quadrature phase component of a single tone during a single orthogonal frequency division multiplexed symbol transmission time period;
• and
• means for determining from the magnitude of said first single one of said In-phase and Quadrature phase signal components of each received control signal an amount of an adjustment to be made, said adjustment corresponding to the control information type;
• means for checking a signal transmitted on a second single one of the In-phase and Quadrature phase components to determine if said single orthogonal frequency division multiplexed symbol transmission time period during which said signal is transmitted and the value of said signal are a function of a wireless device identifier unique to said wireless terminal;
• and
• wherein said first type of information is one of power control information, timing control information and frequency control information.