Serial cancellation receiver design for a coded signal processing engine
An interference cancelling receiver combines data from multiple paths after aligning to transmitter timing, and uses either an equalizer or a Rake receiver to compute symbol estimates. Interference estimates are generated from the symbol estimates, and multiple interference estimates are combined after re-aligning the interference estimates to receiver timing. At least two segments of symbol estimates are computed for each segment of interference cancelled data. Various techniques may be employed for controlling the latency and sequencing of these operations, and the subsystems within the canceller may use different processing clock speeds.
1. An apparatus configured for generating an interference suppressed signal, comprising:
one or more power estimators configured for computing power estimates of components of a received signal;
a control block coupled to the one or more power estimators configured to determine an order of suppression of the components of a received signal based at least in part on the power estimates; and
one or more processing fingers coupled to the control block configured for generating at least one interference suppressed signal stream;
wherein the one or more processing fingers comprises at least one Hadamard transform module configured to compute the amplitudes of a plurality of channels.
2. An apparatus configured for generating an interference suppressed signal, comprising:
one or more power estimators configured for computing power estimates of components of a received signal;
a control block coupled to the one or more power estimators configured to determine an order of suppression of the components of a received signal based at least in part on the power estimates; and
one or more processing fingers coupled to the control block configured for generating at least one interference suppressed signal stream;
wherein the one or more processing fingers comprises a de-spreader configured for despreading an input signal.
3. A receiver for a wireless communication system, said communication system comprising:
a control processor configured for receiving a signal y having one or more data parameters, said control processor configured for selecting which of the one or more data parameters to send to each of one or more fingers, the one or more fingers comprising at least one search finger and at least one tracking finger;
at least one correlator residing in said at least one tracking finger, said at least one correlator being configured to correlate said signal y with a reference signal s n ; and
a Coded Signal Processing Engine (CSPE) residing in said at least one tracking finger and configured for performing interference suppression in the signal y, said CSPE configured for generating a projection from the signal y, signal y comprising, a spread signal matrix s i of the source of interest, signals of other interfering sources s 1 , s 2 , s 3 . . . , s p ; and noise n.
4. The receiver recited in claim 3 , wherein the receiver is further configured to divide the signal y into y i channel and a y Q channel.
5. The receiver recited in claim 4 , wherein said at least one search finger is configured in the y i channel to multiply a pilot Walsh code with a short code to generate a first reference signal if the Walsh code is non-zero.
6. The receiver recited in claim 5 , wherein said at least one search finger is further configured to multiply the first reference signal by an orthogonal projection matrix to generate a second reference signal with at least one interference signal removed.
7. The receiver recited in claim 6 , wherein said at least one search finger is further configured to multiply the second reference signal with the signal y i to generate an intermediate signal.
8. The receiver recited in claim 7 , wherein said at least one search finger is further configured to correlate the intermediate signal by summing the product of y i and the second reference signal over a correlation length N to generate a first one or more summation signals.
9. The receiver recited in claim 8 wherein in the y Q channel, said at least one search finger is further configured to multiply a pilot Walsh code with a short code to generate a first reference signal if the Walsh code is non-zero.
10. The receiver recited in claim 9 , wherein said at least one search finger is further configured to multiply the first reference signal by a respective orthogonal projection matrix to generate a second reference signal having at least one interference signal removed.
11. The receiver recited in claim 10 , wherein said at least one search finger is further configured to multiply the second reference signal with the signal y Q to generate a second intermediate signal.
12. The receiver recited in claim 11 , wherein said at least one search finger is further configured to correlate the second intermediate signal by summing the product of y Q and the second reference signal over a correlation length N in said summer to generate a second one or more summation signals.
13. The receiver recited in claim 12 , wherein said at least one search finger is further configured to process the first one or more summation signals and the second one or more summation signals to select a strongest summation signal.