Method, apparatus, computer program and computer program distribution medium for a communication receiver
View Patent ↗The invention relates to an apparatus comprising, a sampler configured to receive and sample a signal for producing signal samples; a first configured to receive or determinate a scaling factor for a reliability factor and to determine power or energy of an input signal of an interference canceller; a generator configured to generate an estimated replica of a transmitted desired signal by using the signal samples; a residual processor configured to subtract the estimated replica from the input signal of an interference canceller for generating a residual signal and to determine power or energy of the residual signal; and a divider configured to divide the power or energy of the residual signal by the power or energy of the input signal of an interference canceller and a multiplier configured to multiply a result of the division by the scaling factor of a reliability factor.
1. An apparatus comprising:
at least one processor; and
at least one non-transitory memory including computer program code,
wherein the at least one non-transitory memory and the computer program code are configured to cause the at least one processor at least to:
receive and sample a signal for producing signal samples;
determine a scaling factor for a reliability factor and to determine power or energy of an input signal;
generate an estimated replica of a transmitted desired signal by using the signal samples;
subtract the estimated replica of the transmitted desired signal from the input signal for generating a residual signal and to determine power or energy of the residual signal; and
divide the power or energy of the residual signal by the power or energy of the input signal and a multiplier configured to multiply a result of the division by the scaling factor of the reliability factor for obtaining a reliability factor for adjusting equalizer coefficients.
2. The apparatus of claim 1 , wherein the equalizer coefficients are obtained for a chip-level linear turbo equalizer.
3. The apparatus of claim 1 , wherein the estimated replica of the transmitted desired signal is generated as follows:
x
_
=
α
d
W
*
∑
j
=
1
J
d
_
j
+
α
p
c
p
+
α
ctrl
c
^
ctrl
,
wherein
α d denotes an amplitude of the transmitted desired signal,
* denotes a multiplication operation,
W denotes a pre-coding matrix,
Σ denotes a summing operation,
d j denotes estimated data chips on a jth code channel,
J denotes a number of code channels in use,
α p denotes an amplitude of a pilot channel (such as a common pilot channel (CPICH),
c p denotes pilot chips transmitted from primary and secondary transmission antennas,
α ctrl denotes an amplitude for control channels of a desired user control channel (such as a primary common control physical channel (PCCPCH)+signalling channel (SCH)), and
ĉ ctrl denotes chips pertaining to the desired user control channels.
4. The apparatus of claim 1 , wherein the reliability factor for the adjusting equalizer coefficients, v is obtained as follows:
v
=
β
*
r
res
H
r
res
r
H
r
=
β
*
(
r
-
H
*
(
α
d
W
*
∑
j
=
1
J
d
_
j
+
α
p
c
p
+
α
ctrl
+
c
^
ctrl
)
)
H
*
r
H
(
r
-
H
*
(
α
d
W
*
∑
j
=
1
J
d
_
j
+
α
p
c
p
+
α
ctrl
+
c
^
ctrl
)
)
r
wherein
r res denotes a residual signal,
r denotes an input signal,
β denotes a scaling factor for a reliability factor,
a d denotes an amplitude of the transmitted desired signal,
H denotes a channel convolution matrix,
* denotes a multiplication operation,
W denotes a pre-coding matrix,
Σ denotes a summing operation,
d j denotes estimated data chips on an ith code channel,
J denotes a number of code channels in use,
H denotes a complex-conjugate (Hermitian) matrix,
α p denotes an amplitude of a pilot channel (such as a common pilot channel (CPICH),
c p denotes pilot chips transmitted from primary and secondary transmission antennas,
a ctrl denotes an amplitude for control channels of a desired user control channel (such as a primary common control physical channel (PCCPCH)+signalling channel (SCH)), and
ĉ ctrl denotes chips pertaining to the desired user control channels.
5. The apparatus of claim 4 , wherein at a first iteration, when no feedback signal from a decoder is available, the reliability factor for the adjusting equalizer coefficients is 1.
6. The apparatus of claim 4 , wherein in the case of a perfect recovery of transmitted bits, the reliability factor for the adjusting equalizer coefficients is 0.
7. The apparatus of claim 6 , wherein the apparatus comprises a user terminal.
8. A method comprising:
determining a scaling factor for a reliability factor;
receiving and sampling a signal for producing signal samples;
determining power or energy of an input signal;
generating an estimated replica of a transmitted desired signal by using the signal samples;
subtracting the estimated replica of the transmitted desired signal from the input signal for generating a residual signal;
determining power or energy of the residual signal; and
dividing the power or energy of the residual signal by the power or energy of the input signal and multiplying a result of the division by the scaling factor of the reliability factor for obtaining a reliability factor for adjusting equalizer coefficients.
9. The method of claim 8 , wherein the equalizer coefficients are obtained for a chip-level linear turbo equalizer.
10. The method of claim 8 , wherein the estimated replica of the transmitted desired signal is generated as follows:
x
_
=
α
d
W
*
∑
j
=
1
J
d
_
j
+
α
p
c
p
+
α
ctrl
c
^
ctrl
,
wherein
a d denotes an amplitude of the transmitted desired signal,
* denotes a multiplication operation,
W denotes a pre-coding matrix,
Σ denotes a summing operation,
d j denotes estimated data chips on an ith code channel,
J denotes a number of code channels in use
α p denotes an amplitude of a pilot channel (such as a common pilot channel (CPICH),
c p denotes pilot chips transmitted from primary and secondary transmission antennas,
α ctrl denotes an amplitude for control channels of a desired user control channel (such as a primary common control physical channel (PCCPCH)+signalling channel (SCH)), and
ĉ ctrl denotes chips pertaining to the desired user control channels.
11. The method of claim 8 , wherein the reliability factor for the adjusting equalizer coefficients, v, is obtained as follows:
v
=
β
*
r
res
H
r
res
r
H
r
=
β
*
(
r
-
H
*
(
α
d
W
*
∑
j
=
1
J
d
_
j
+
α
p
c
p
+
α
ctrl
+
c
^
ctrl
)
)
H
*
r
H
(
r
-
H
*
(
α
d
W
*
∑
j
=
1
J
d
_
j
+
α
p
c
p
+
α
ctrl
+
c
^
ctrl
)
)
r
wherein
r res denotes a residual signal,
r denotes an input signal,
β denotes a scaling factor for a reliability factor,
α d denotes an amplitude of the transmitted desired signal,
H denotes a channel convolution matrix,
* denotes a multiplication operation,
W denotes a pre-coding matrix,
Σ denotes a summing operation,
d j denotes estimated data chips on and ith code channel,
J denotes a number of code channels in use,
H denotes a complex-conjugate (Hermitian) matrix,
α p denotes an amplitude of a pilot channel (such as a common pilot channel (CPICH),
c p denotes pilot chips transmitted from primary and secondary transmission antennas,
a ctrl denotes an amplitude for control channels of a desired user control channel (such as a primary common control physical channel (PCCPCH)+signalling channel (SCH)), and
ĉ ctrl denotes chips pertaining to the desired user control channels.
12. The method of claim 11 , wherein at a first iteration, when no feedback signal from a decoder is available, the reliability factor for the adjusting equalizer coefficients is 1.
13. The method of claim 11 , wherein in the case of a perfect recovery of transmitted bits, the reliability factor for the adjusting equalizer coefficients is 0.
14. A computer program product comprising at least one non-transitory computer-readable storage medium having computer-readable program instructions for one or more programs stored therein, the computer-readable program instructions comprising program instructions configured to cause an apparatus to perform a method comprising:
determining a scaling factor for a reliability factor;
receiving and sampling a signal for producing signal samples;
determining power or energy of an input signal;
generating an estimated replica of a transmitted desired signal by using the signal samples;
subtracting the estimated replica of the transmitted desired signal from the input signal for generating a residual signal;
determining power or energy of the residual signal; and
dividing the power or energy of the residual signal by the power or energy of the input signal and multiplying a result of the division by the scaling factor of the reliability factor for obtaining a reliability factor for adjusting equalizer coefficients.
15. The computer program product of claim 14 , wherein at a first iteration, when no feedback signal from a decoder is available, the reliability factor for the adjusting equalizer coefficients is 1.
16. The computer program product of claim 14 , wherein in the case of a perfect recovery of transmitted bits, the reliability factor for the adjusting equalizer coefficients is 0.
17. The computer program product of claim 14 , wherein the estimated replica of the transmitted desired signal is generated as follows:
x
_
=
α
d
W
*
∑
j
=
1
J
d
_
j
+
α
p
c
p
+
α
ctrl
c
^
ctrl
,
wherein
a d denotes an amplitude of a transmitted desired signal,
* denotes a multiplication operation,
W denotes a pre-coding matrix,
Σ denotes a summing operation,
d j denotes estimated data chips on an ith code channel,
J denotes a number of code channels in use,
α p denotes an amplitude of a pilot channel (such as a common pilot channel (CPICH),
c p denotes pilot chips transmitted from primary and secondary transmission antennas,
α ctrl denotes an amplitude for control channels of a desired user control channel (such as a primary
common control physical channel (PCCPCH)+signalling channel (SCH)), and ctrl
ĉ ctrl denotes chips pertaining to the desired user control channels.
18. The computer program product of claim 14 , wherein the reliability factor for the adjusting equalizer coefficients, v, is obtained as follows:
v
=
β
*
r
res
H
r
res
r
H
r
=
β
*
(
r
-
H
*
(
α
d
W
*
∑
j
=
1
J
d
_
j
+
α
p
c
p
+
α
ctrl
+
c
^
ctrl
)
)
H
*
r
H
(
r
-
H
*
(
α
d
W
*
∑
j
=
1
J
d
_
j
+
α
p
c
p
+
α
ctrl
+
c
^
ctrl
)
)
r
wherein
r res denotes a residual signal,
r denotes an input signal,
β denotes a scaling factor for a reliability factor,
α d denotes an amplitude of a transmitted desired signal,
H denotes a channel convolution matrix,
* denotes a multiplication operation,
W denotes a pre-coding matrix,
Σ denotes a summing operation,
d j denotes estimated data chips on an ith code channel,
J denotes a number of code channels in use,
H denotes a complex-conjugate (Hermitian) matrix,
α p denotes an amplitude of a pilot channel (such as a common pilot channel (CPICH),
c p denotes pilot chips transmitted from primary and secondary transmission antennas,
α ctrl denotes an amplitude for control channels of a desired user control channel (such as a primary
common control physical channel (PCCPCH)+signalling channel (SCH)), and
ĉ ctrl denotes chips pertaining to the desired user control channels.
19. The computer program product of claim 14 , wherein the equalizer coefficients are obtained for a chip-level linear turbo equalizer.