Method and apparatus that facilitates estimating Doppler spread for uplink transmissions
Methods, apparatuses, and computer program products are disclosed for performing a Doppler spread estimation. In a first embodiment, an energy associated with a communication from a wireless terminal is ascertained based on at least one pilot symbol and at least one data symbol. Each of an energy variance and a noise variance are then determined to facilitate estimating a speed of the wireless terminal based on the energy variance normalized by the noise variance. In another embodiment, a signal received from a wireless terminal is decoded and replicated. A channel estimate associated with a set of data symbols is then ascertained from the replica, which is used to estimate the speed of the wireless terminal.
1. A method that facilitates performing a Doppler spread estimation, the method comprising:
receiving a communication from a wireless terminal, wherein the communication includes at least two symbols;
ascertaining an energy associated with the communication, wherein the energy is based on the at least two symbols;
determining an energy variance and a noise variance; and
estimating a speed of the wireless terminal based on the energy variance normalized by the noise variance.
2. The method of claim 1 , wherein the communication is received via an uplink channel having a constant modulus.
3. The method of claim 2 , wherein the uplink channel is associated with a Physical Uplink Control Channel.
4. The method of claim 3 , wherein the uplink channel is associated with a Channel Quality Indicator.
5. The method of claim 2 , wherein the uplink channel is associated with a Physical Uplink Shared Channel.
6. The method of claim 1 , further comprising calculating a metric based on the energy variance and the noise variance, wherein the estimating includes comparing the metric to a threshold.
7. The method of claim 6 , wherein the calculating comprises calculating a short term average associated with the energy, and wherein the metric is based on the short term average.
8. The method of claim 7 , wherein the calculating comprises calculating a long term average of the short term average associated with the energy, and wherein the metric is based on the long term average.
9. The method of claim 6 , wherein the calculating comprises calculating a short term energy variance, and wherein the metric is based on the short term energy variance.
10. The method of claim 9 , wherein the calculating comprises calculating a long term average of the short term energy variance, and wherein the metric is based on the long term average.
11. The method of claim 10 , wherein the metric is directly proportional to the long term average of the short term energy variance.
12. The method of claim 6 , wherein the calculating comprises calculating a long term average of a short term noise variance associated with the energy, and wherein the metric is based on the long term average.
13. The method of claim 1 , wherein the at least two symbols comprise any combination of data symbols or pilot symbols.
14. An apparatus configured to facilitate performing a Doppler spread estimation, the apparatus comprising:
a processor configured to execute computer executable components stored in memory, the components including:
a communication component configured to receive a communication from a wireless terminal, wherein the communication includes at least two symbols;
an energy component configured to ascertain an energy associated with the communication, wherein the energy is based on the at least two symbols;
a variance component configured to determine an energy variance and a noise variance; and
a speed component configured to estimate a speed of the wireless terminal based on the energy variance normalized by the noise variance.
15. The apparatus of claim 14 , wherein the communication component is configured to receive the communication via an uplink channel having a constant modulus.
16. The apparatus of claim 15 , wherein the uplink channel is associated with a Physical Uplink Control Channel.
17. The apparatus of claim 16 , wherein the uplink channel is associated with a Channel Quality Indicator.
18. The apparatus of claim 15 , wherein the uplink channel is associated with a Physical Uplink Shared Channel.
19. The apparatus of claim 14 , wherein the speed component is configured to calculate a metric based on the energy variance and the noise variance, and wherein the speed component is further configured to estimate the speed by comparing the metric to a threshold.
20. The apparatus of claim 19 , wherein the speed component is configured to calculate a short term average associated with the energy, and wherein the metric is based on the short term average.
21. The apparatus of claim 20 , wherein the speed component is configured to calculate a long term average of the short term average associated with the energy, and wherein the metric is based on the long term average.
22. The apparatus of claim 19 , wherein the speed component is configured to calculate a short term energy variance, and wherein the metric is based on the short term energy variance.
23. The apparatus of claim 22 , wherein the speed component is configured to calculate a long term average of the short term energy variance, and wherein the metric is based on the long term average.
24. The apparatus of claim 23 , wherein the metric is directly proportional to the long term average of the short term energy variance.
25. The apparatus of claim 19 , wherein the speed component is configured to calculate a long term average of a short term noise variance associated with the energy, and wherein the metric is based on the long term average.
26. The apparatus of claim 14 , wherein the at least two symbols comprise any combination of data symbols or pilot symbols.
27. A computer program product that facilitates performing a Doppler spread estimation, comprising:
a computer-readable storage medium comprising code for causing at least one computer to:
receive a communication from a wireless terminal, wherein the communication includes at least two symbols;
ascertain an energy associated with the communication, wherein the energy is based on the at least two symbols;
determine an energy variance and a noise variance; and
estimate a speed of the wireless terminal based on the energy variance normalized by the noise variance.
28. The computer program product of claim 25 , the code further causing the at least one computer to calculate a metric based on the energy variance and the noise variance, wherein the speed is estimated by comparing the metric to a threshold.
29. The computer program product of claim 26 , the code further causing the at least one computer to calculate a short term average associated with the energy, wherein the metric is based on the short term average.
30. The computer program product of claim 27 , the code further causing the at least one computer to calculate a long term average of the short term average associated with the energy, wherein the metric is based on the long term average.
31. The computer program product of claim 26 , the code further causing the at least one computer to calculate a short term energy variance, wherein the metric is based on the short term energy variance.
32. The computer program product of claim 29 , the code further causing the at least one computer to calculate a long term average of the short term energy variance, wherein the metric is based on the long term average.
33. The computer program product of claim 30 , wherein the metric is directly proportional to the long term average of the short term energy variance.
34. The computer program product of claim 26 , the code further causing the at least one computer to calculate a long term average of a short term noise variance associated with the energy, wherein the metric is based on the long term average.
35. The computer program product of claim 27 , wherein the at least two symbols comprise any combination of data symbols or pilot symbols.
36. An apparatus configured to facilitate performing a Doppler spread estimation, the apparatus comprising:
means for receiving a communication from a wireless terminal, wherein the communication includes at least two symbols;
means for ascertaining an energy associated with the communication, wherein the energy is based on the at least two symbols;
means for determining an energy variance and a noise variance; and
means for estimating a speed of the wireless terminal based on the energy variance normalized by the noise variance.
37. The apparatus of claim 33 , wherein the means for receiving is configured to receive the communication via an uplink channel having a constant modulus.
38. The apparatus of claim 34 , wherein the uplink channel is associated with a Physical Uplink Control Channel.
39. The apparatus of claim 35 , wherein the uplink channel is associated with a Channel Quality Indicator.
40. The apparatus of claim 34 , wherein the uplink channel is associated with a Physical Uplink Shared Channel.
41. The apparatus of claim 36 , wherein the at least two symbols comprise any combination of data symbols or pilot symbols.