Joint synchronization and impairments estimation using known data patterns
View Patent ↗Synchronization and impairment estimations can be performed jointly, thereby saving valuable time for decoding of the received packet. An initial synchronization in a TDMA system can be performed. Using this synchronization, the frequency offset choices and timing offset choices can be advantageously bounded within predetermined ranges. At this point, an algorithm can find the minimum error that gives the best frequency offset choice and timing offset choice combination over their respective ranges, together with the estimates of the signal magnitude and phase and at least one of a DC offset magnitude and phase, and a spur magnitude and phase.
1. A method of providing synchronization and impairment estimations in a wireless communication system, the method comprising:
performing an initial synchronization;
bounding a frequency offset within a first range based on the initial synchronization and providing a first discrete number of frequency offset choices within the first predetermined range;
bounding a timing offset within a second range based on the initial synchronization and providing a second discrete number of timing offset choices within the second range; and
using a known data pattern included in a packet and a known receiver spur frequency, determining a frequency offset choice and timing offset choice combination over the first range and the second range that gives a minimum of an error measurement, producing thereby estimates of a signal magnitude and phase and at least one of a DC offset magnitude and phase, and a spur magnitude and phase.
2. The method of claim 1 , wherein determining the minimum of the error measurement includes using a least mean square (LMS) algorithm including the signal magnitude and phase, the DC offset magnitude and phase, and the spur magnitude and phase.
3. The method of claim 2 , wherein the LMS algorithm is represented by the equation:
(
A
^
B
^
C
^
)
=
(
M
T
M
)
-
1
M
T
y
⇀
.
4. The method of claim 3 , wherein the minimum of the error measurement is represented by the equation:
error
tim_offset
,
freq_offset
=
y
⇀
tim_offset
-
(
A
^
x
⇀
ⅇ
j
w
freq_offset
t
+
B
^
+
C
^
ⅇ
j
w
spur
t
)
2
.
5. The method of claim 3 , wherein the matrix (M T M) −1 M T has been pre-computed.
6. The method of claim 3 , wherein the sampled received waveform y is saved in memory before processing begins.
7. A software program for jointly providing synchronization and impairment estimations in a wireless communication system, the software program comprising:
code for bounding a frequency offset within a first range based on an initial synchronization and providing a first discrete number of frequency offset choices within the first range;
code for bounding a timing offset within a second range based on the initial synchronization and providing a second discrete number of timing offset choices within the second range;
code for using a known data pattern included in a packet and a known receiver spur frequency; and
code for determining a minimum of an error measurement that gives a best frequency offset choice and timing offset choice combination over the first and second predetermined ranges, together with estimates of a signal magnitude and phase and at least one of a DC offset magnitude and phase, and a spur magnitude and phase.
8. The software program of claim 7 , wherein the code for determining the minimum of the error measurement includes code for using a least mean square (LMS) algorithm including the signal magnitude and phase and at least one of a DC offset magnitude and phase, and a spur magnitude and phase.
9. The software program of claim 8 , wherein the LMS algorithm is represented by the equation:
(
A
^
B
^
C
^
)
=
(
M
T
M
)
-
1
M
T
y
⇀
.
10. The software program of claim 9 , wherein the minimum of the error measurement is represented by the equation:
error
tim_offset
,
freq_offset
=
y
⇀
tim_offset
-
(
A
^
x
⇀
ⅇ
j
w
freq_offset
t
+
B
^
+
C
^
ⅇ
j
w
spur
t
)
2
.
11. A method of providing synchronization and impairment estimations in a wireless communication system, the method comprising:
performing an initial synchronization;
bounding a frequency offset within a first range based on the initial synchronization;
bounding a timing offset within a second range based on the initial synchronization; and
using a known data pattern included in a packet and a known receiver spur frequency, determining a frequency offset choice and timing offset choice combination over the first range and the second range that gives a minimum of an error measurement, thereby producing estimates of a signal magnitude and phase and at least one of a DC offset magnitude and phase, and a spur magnitude and phase.