Method and apparatus for demodulation and power control bit detection in a spread spectrum communication system

A receiver circuit for receiving a spread spectrum communication signal over a communication channel the spread spectrum communication signal including a pilot channel signal, a traffic channel signal and a power control designator, the receiver circuit comprising:

• a despreader configured to receive the spread spectrum communication signal and a despreading code, the despreader producing a despread signal in response to the spread spectrum communication signal and the despreading code;
• a pilot channel decoder coupled to the despreader, the pilot channel decoder applying a pilot channel code to detect the pilot channel signal;
• a first channel estimator coupled to the pilot channel decoder for producing a first estimated channel gain and a first estimated channel phase;
• a second channel estimator coupled to the pilot channel decoder for producing a second estimated channel gain and a second estimated channel phase;
• a traffic channel decoder coupled to the despreader, the traffic channel decoder applying a user specific traffic code to detect the traffic channel signal including the power control designator;
• a delay element coupled to the traffic channel decoder for delaying the traffic channel signal a first predetermined time, the delay element producing a delayed traffic channel signal;
• a short delay element coupled to the traffic channel decoder for delaying the power control designator a second predetermined time, the second predetermined time being less than the first predetermined time, the short delay element producing a delayed power control designator;
• a traffic channel demodulator coupled to the delay element and the first channel estimator for demodulating the delayed traffic channel signal in response to the first estimated channel gain and the first estimated channel phase;
• and
• a power control demodulator coupled to the short delay element and the second channel estimator for demodulating the delayed power control designator in response to the second estimated channel gain and the second estimated channel phase.

A method for demodulating DS-CDMA signals which include a pilot channel signal, a traffic channel signal and a power control channel, the method comprising the steps of:

• (a) jointly estimating a traffic channel phase and a traffic channel gain;
• (b) separately estimating a power control channel phase and a power control channel gain;
• (c) delaying the traffic channel signal by a first predetermined time to produce a delayed traffic channel signal;
• (d) demodulating the delayed traffic channel signal using the traffic channel phase and the traffic channel gain;
• (e) delaying the power control channel by a second predetermined time to produce a delayed power control channel;
• and
• (f) demodulating the delayed power control channel using the power control channel phase and the power control channel gain.

A method of demodulating a spread spectrum communication signal, the spread spectrum communication signal including a pilot signal, the pilot signal having a predetermined form for decoding by all receivers, the method comprising the steps of:

• receiving the spread spectrum communication signal over a communication channel;
• detecting the pilot signal in the spread spectrum communication signal and producing pilot symbols;
• detecting a traffic channel signal in the spread spectrum communication signal and producing traffic symbols;
• filtering the pilot symbols to estimate the channel gain and the channel phase;
• delaying only the traffic channel symbols a predetermined time to produce a delayed signal;
• and
• demodulating the delayed signal using the estimated channel phase and channel gain.

A method of demodulating a spread spectrum communication signal, the method comprising the steps of:

• receiving the spread spectrum communication signal over a communication channel;
• detecting a pilot channel signal in the spread spectrum communication signal by applying a pilot code to the despread signal and decoding the despread signal in response to the pilot code to produce the pilot channel signal;
• detecting a traffic channel signal in the spread spectrum communication signal by applying a pseudorandom noise pattern to the spread spectrum communication signal and despreading the spread spectrum communication signal in response to the pseudorandom noise pattern to produce a despread signal;
• filtering the pilot channel signal to estimate a channel gain and a channel phase for the spread spectrum communication signal;
• delaying only the traffic channel signal a predetermined time to produce a delayed signal;
• and
• demodulating the delayed signal using the estimated channel phase and channel gain.

A receiver configured to be coupled to an antenna for receiving a spread spectrum communication signal over a communication channel, the spread spectrum communication signal including a pilot signal, the receiver comprising:

• a despreader configured to be coupled to the antenna for despreading the spread spectrum communication signal and producing a pilot channel in response to the pilot signal and a traffic channel;
• a filter coupled to the despreader for producing an estimate of channel gain and channel phase for the communication channel in response to the pilot channel;
• a delay element coupled to the despreader for delaying the traffic channel a predetermined time and producing a delayed traffic channel;
• and
• a demodulator coupled to the delay element and the filter, the demodulator demodulating the delayed traffic channel in response to the channel phase and the channel gain.

A receiver configured to be coupled to an antenna for receiving a spread spectrum communication signal over a communication channel, the receiver comprising:

• a despreader configured to be coupled to the antenna for despreading the spread spectrum communication signal and producing a pilot channel signal and a traffic channel signal;
• a filter coupled to the despreader for producing an estimate of channel gain and channel phase for the communication channel;
• a delay element coupled to the despreader for delaying the traffic channel signal a predetermined time and producing a delayed traffic channel signal;
• a demodulator coupled to the delay element and the filter, the demodulator demodulating the delayed traffic channel signal in response to the channel phase and the channel gain;
• and
• a conjugate generator coupled between the filter and the demodulator, the conjugate generator determining a complex conjugate of a signal produced by the filter and providing the complex conjugate to the demodulator.

A receiver configured to be coupled to an antenna for receiving a spread spectrum communication signal over a communication channel, the receiver comprising:

• a despreader configured to be coupled to the antenna for despreading the spread spectrum communication signal and producing a pilot channel signal and a traffic channel signal, the pilot channel signal comprising a series of pilot symbols;
• a filter coupled to the despreader for producing an estimate of channel gain and channel phase for the communication channel, the filter comprising a buffer for storing a predetermined number of pilot symbols and a summer, the buffer shifting a new pilot symbol into the buffer and shifting an oldest pilot symbol out of the buffer, the summer summing contents of the buffer and the new pilot symbol to produce the estimate of channel gain and channel phase;
• a delay element coupled to the despreader for delaying the traffic channel signal a predetermined time and producing a delayed traffic channel signal;
• and
• a demodulator coupled to the delay element and the filter, the demodulator demodulating the delayed traffic channel signal in response to the channel phase and the channel gain.

A method for demodulating a direct sequence code division multiple access (DS-CDMA) signal received in a receiver, the DS-CDMA signal including traffic symbols and pilot symbols, the method comprising the steps of:

• filtering the pilot symbols to produce an estimate of channel gain and channel phase;
• delaying the traffic symbols for a predetermined time, producing delayed traffic symbols;
• and
• demodulating the delayed traffic symbols in response to the channel gain and phase.