1. A method of processing signals received from channels exposed to multi-path propagation via a plurality of diversity antennas, each of said received signals comprising at least one pilot signal, comprising:
detecting a set of multi-path components for each of said received signals;
detecting said at least one pilot signal from a plurality of multi-path components in said set of multi-path components;
computing a set of channel coefficients from said multi-path components used to detect said at least one pilot signal, said set of channel coefficients being organized as a channel coefficient vector; and
estimating from said channel coefficient vector a set of combining weights to be applied to said received signals, said estimating from said channel coefficient vector a set of combining weights comprising:
computing a spatial correlation matrix of said channel coefficient vector by neglecting the correlations between multi-path components of said channel coefficient vector having different delays, whereby said correlation matrix is a block diagonal matrix comprising null coefficients other than for non-null sub-matrixes arranged along the diagonal of said correlation matrix, wherein said sub-matrixes have a size equal to the number of said diversity antennas, wherein two diversity antennas are used;
deriving from said spatial correlation matrix a resulting matrix by calculating the inverse of said sub-matrixes or a scaled version thereof by performing only sign inversions and element swapping, wherein calculating the determinant of said sub-blocks and dividing the inverted sub-blocks by said determinants are omitted; and
multiplying said resulting matrix and said channel coefficient vector in order to obtain said set of combining weights.
2. The method of claim 1, comprising averaging the coefficients of said correlation matrix over a predetermined time interval.
3. The method of claim 1, comprising averaging the coefficients of said channel coefficient vector, said resulting matrix being multiplied with said averaged channel coefficient vector in order to obtain said set of combining weights.
4. The method of claim 1, wherein at least one of said received signals comprises at least one data signal, and wherein the method comprises:
multiplying said set of combining weights with said set of multi-path components of said received signal, and summing the result of said multiplications in order to obtain a multi-path free version of said received signal; and
detecting said at least one data signal in said multi-path free version of said received signal.
5. The method of claim 1, wherein at least one of said received signals comprises at least one data signal, and wherein the method comprises:
detecting multi-path components of said at least one data signal in said set of multi-path components of said received signal; and
multiplying said set of combining weights with said multi-path components of said at least one data signal, and summing the result of said multiplications in order to obtain a multi-path free version of said data signal.
6. The method of claim 1, wherein at least one of said received signals comprises at least one data signal, and wherein said at least one pilot signal and said at least one data signal are spread with at least one orthogonal variable spreading factor, and wherein the method comprises detecting said at least one pilot signal and said at least one data signal, wherein said detecting involves de-spreading said at least one pilot signal and said at least one data signal.
7. The method of claim 1, comprising:
initializing an iterative channel tracking procedure with said set of combining weights; and
tracking channel variations during data reception by updating said combining weights with said iterative channel tracking procedure.
8. The method of claim 7, wherein initializing an iterative channel tracking procedure with said set of combining weights comprises performing a number of iterations of said iterative channel tracking procedure before any data are received in order to obtain refined versions of said combining weights to be applied to said received signals.
9. The method of claim 7, wherein said iterative channel tracking procedure is a least mean square or normalized least mean square iterative procedure.
10. The method of claim 7, wherein said iterative channel tracking procedure operates directly on said multi-path components of said received signal.
11. A receiver for receiving signals from channels exposed to multi-path propagation via a plurality of diversity antennas, said received signals comprising at least one pilot signal, wherein the receiver is configured for performing a method comprising:
detecting a set of multi-path components for each of said received signals;
detecting said at least one pilot signal from a plurality of multi-path components in said set of multi-path components;
computing a set of channel coefficients from said multi-path components used to detect said at least one pilot signal, said set of channel coefficients being organized as a channel coefficient vector; and
estimating from said channel coefficient vector a set of combining weights to be applied to said received signals, said estimating from said channel coefficient vector a set of combining weights comprising:
computing a spatial correlation matrix of said channel coefficient vector by neglecting the correlations between multi-path components of said channel coefficient vector having different delays, whereby said correlation matrix is a block diagonal matrix comprising null coefficients other than for non-null sub-matrixes arranged along the diagonal of said correlation matrix, wherein said sub-matrixes have a size equal to the number of said diversity antennas, wherein two diversity antennas are used;
deriving from said spatial correlation matrix a resulting matrix by calculating the inverse of said sub-matrixes or a scaled version thereof by performing only sign inversions and element swapping, wherein calculating the determinant of said sub-blocks and dividing the inverted sub-blocks by said determinants are omitted; and
multiplying said resulting matrix and said channel coefficient vector in order to obtain said set of combining weights.
12. The receiver of claim 11, wherein said receiver is a high speed packet access receiver.
13. A non-transitory computer readable medium containing a computer program product loadable into the memory of a computer and comprising software code portions that when executed on the computer perform a method comprising:
detecting a set of multi-path components for each of said received signals;
detecting said at least one pilot signal from a plurality of multi-path components in said set of multi-path components;
computing a set of channel coefficients from said multi-path components used to detect said at least one pilot signal, said set of channel coefficients being organized as a channel coefficient vector; and
estimating from said channel coefficient vector a set of combining weights to be applied to said received signals, said estimating from said channel coefficient vector a set of combining weights comprising:
computing a spatial correlation matrix of said channel coefficient vector by neglecting the correlations between multi-path components of said channel coefficient vector having different delays, whereby said correlation matrix is a block diagonal matrix comprising null coefficients other than for non-null sub-matrixes arranged along the diagonal of said correlation matrix, wherein said sub-matrixes have a size equal to the number of said diversity antennas, wherein two diversity antennas are used;
deriving from said spatial correlation matrix a resulting matrix by calculating the inverse of said sub-matrixes or a scaled version thereof by performing only sign inversions and element swapping, wherein calculating the determinant of said sub-blocks and dividing the inverted sub-blocks by said determinants are omitted; and
multiplying said resulting matrix and said channel coefficient vector in order to obtain said set of combining weights.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An active hybrid circuit for a full duplex channel, comprising:
a transmit digital-to-analog converter having a positive output port and a negative output port for generating an analog transmit signal;
a receive analog-to-digital converter having a positive input port and a negative input port for receiving an analog receive signal;
a duplicated voltage digital-to-analog converter having a positive output port and a negative output port for generating a duplicated voltage, the duplicated voltage including a duplicate of the analog transmit signal of the transmit digital-to-analog converter;
a plurality of signal combiners each electrically connected at a first input thereof to the positive output port and negative output port of the transmit digital-to-analog converter and at an output thereof to the positive input port and the negative input port of the receive analog-to-digital converter, the plurality of signal combiners each connected at a second input thereof to the positive output port and the negative output port of the duplicated voltage digital-to-analog converter, the plurality of signal combiners each subtracting the duplicated voltage from the analog transmit signal; and
a digital signal processor coupled to the receive analog-to-digital converter and responsive to a digital signal therefrom to provide a digital control signal, wherein the duplicated voltage produced by the duplicated voltage digital-to-analog converter is adjusted in accordance with the digital control signal.
2. The active hybrid circuit for a full duplex channel of claim 1, further comprising:
a gain amplifier electrically connected to the plurality of signal combiners for amplifying the receive signal; and
an anti-aliasing filter electrically to interposed between the gain amplifier and the receive analog-to-digital converter for canceling the alias signal of the receive signal.
3. The active hybrid circuit for a full duplex channel of claim 1, further comprising an adjustable module electrically interposed between the digital signal processor and the duplicated voltage digital-to-analog converter, the adjustable module receiving the digital control signal and producing an adjustment signal responsive thereto, the adjustment signal being provided to the duplicated voltage digital-to-analog converter for producing responsive thereto the adjusted duplicated voltage.
4. The active hybrid circuit for a full duplex channel of claim 3, wherein the adjustable module includes a digital adjustable resistor receiving the digital control signal and responsive thereto adjusting a reference voltage of the duplicated voltage digital-to-analog converter.
5. The active hybrid circuit for a full duplex channel of claim 3, wherein the adjustable module includes a digital adjustable resistor in a gain control circuit of an operational amplifier, the digital adjustable resistor receiving the digital control signal and responsive thereto adjusting the output voltage of the operational amplifier.
6. The active hybrid circuit for a full duplex channel of claim 1, wherein the transmit digital-to-analog converter includes a current output drive stage.
7. The active hybrid circuit for a full duplex channel of claim 1, wherein the duplicated voltage digital-to-analog converter includes a current scale network, an operational amplifier and a resistor.
8. A method for processing signals in an active hybrid circuit for a full duplex channel, the active hybrid circuit for a full duplex channel including a transmitter in a current driving mode, a receiver and a transmit line, the method comprising:
generating a transmit signal with a current output driver in the transmitter;
generating a duplicated voltage corresponding to an output drive current of the current output driver in a load resistor of in the transmission line;
combining the duplicated voltage and a receive signal at the receiver to cancel an echo signal coupled to the receiver from the transmit signal;
converting the receive signal into a digital signal; and
adjusting the duplicated voltage in accordance with the digital signal.
9. The method for processing signals of an active hybrid circuit for a full duplex channel of claim 8, further including the step of anti-aliasing the echo-cancelled receive signal.
10. The method for processing signals of an active hybrid circuit for a full duplex channel of claim 8, further comprising the step of calculating a fine-tuning voltage from the digital signal so as to cancel a voltage overshoot in the receive signal caused by responses of components.
11. The method for processing signals of an active hybrid circuit for a full duplex channel of claim 10, wherein the fine-tuning voltage calculating step is performed by a digital signal processor.
12. The method for processing signals of an active hybrid circuit for a full duplex channel of claim 8 further including the step of amplifying the receive signal prior to the receive signal converting step.