Compensation for Propagation Delay in a Wireless Communication System

• US 20110039497A1
• Filed: 02/27/2009
• Published: 02/17/2011
• Est. Priority Date: 04/25/2008
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Jongren, George, Hammarwall, David
• Granted Patent: US 9,614,593 B2
• Time in Patent Office: Days
• US Class Current: 455/63.1
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 3/2682 Time delay steered arrays
• CPC Class Codes: H04B 17/364 Delay profiles
• CPC Class Codes: H04B 7/04 using two or more spaced independent antennas

Abstract

In a first aspect the present invention relates to a method of compensating for propagation delay in a wireless communication system. A first base station is in communication with a first plurality of antenna units which are adapted to be in wireless communication with a first terminal. The first terminal having a terminal antenna. The first plurality of antenna units is spatially separated. The method according to the first aspect comprises the steps of determining relative propagation delay from each of the first plurality of antenna units to the terminal antenna and using the determined propagation delay to establish a delay profile to compensate for propagation delay from each of the antenna units to the first terminal and applying the delay profile to a transmission between the base station and the terminal. In a second aspect the present invention further relates to a system implementing the method according to the first aspect.

Claims

1-16. -16. (canceled)

17. A method of compensating for propagation delay in a wireless communication system, wherein a processing unit is in communication with a first plurality of antenna units being in wireless communication with at least a first terminal, each terminal having a terminal antenna, the first plurality of antenna units being spatially separated, the method comprising:

determining relative propagation delay from each of the first plurality of antenna units to the terminal antenna of said first terminal,

establishing a delay profile specific for each targeted terminal using the determined relative propagation delay, and

compensating for the determined relative propagation delay from each antenna unit to said first terminal by applying the delay profile to a transmission between the processing unit and said first terminal.

18. The method according to claim 17, wherein the transmission is from the processing unit to said first terminal or from said first terminal to the processing unit.

19. The method according to claim 17, wherein one of the first plurality of antenna units uses a multitude of antennas.

20. The method according to claim 17, wherein the processing unit is a base station or a Node B.

21. The method according to claim 17, wherein said first terminal uses a plurality of antennas.

22. The method according to claim 17, wherein the processing unit is in communication with a third plurality of terminals.

23. The method according to claim 17, wherein the relative propagation delay between each of the first plurality of antenna units and said first terminal or between each of the first plurality of antenna units and each of a second plurality of terminals are determined in the frequency domain, wherein the method further comprises:

evaluating phase differences between propagation channels between said first terminal and multiple antenna units, or between a terminal in the second plurality of terminals and multiple antenna units, for two different frequencies;

estimating propagation time differences from the slope of one line being fitted to the evaluated phase differences over frequency.

24. The method according to claim 23, wherein phase differences are evaluated for a fourth plurality of frequencies.

25. The method according to claim 23, wherein each propagation time difference is estimated from a fifth plurality of fitted lines, with one or a sixth plurality of slopes.

26. The method according to claim 17, wherein the propagation delay between each of the first plurality of antenna units and said first terminal or each of a second plurality of terminals are determined using the equation:

Θ

_kl^(m,n)(f)−

Θ

<sub>k′

l</sub><sup>(m′

,n)</sup>(f)=φ

_kl^(m,n)(f)−

φ

<sub>k′

l</sub><sup>(m′

,n)</sup>(f)+Δ

_mm′

⁽ⁿ⁾f,

wherein Δ

_mm′

⁽ⁿ⁾=Σ

^(m,n)−

Σ

<sup>(m′

,n)</sup> is an estimate of the time difference between signals from the n'"'"'th terminal arriving at antenna units m and m′

of the first plurality of antenna units, τ

^(m,n) is the time difference induced by the propagation channel between the processing unit and the second plurality of antennas of terminal n, Θ

_kl^(m,n)(f)−

Θ

<sub>k′

l</sub><sup>(m′

,n)</sup>(f) is an estimate of phase difference of two channels, and φ

_kl^(m,n)(f)−

φ

<sub>k′

l</sub><sup>(m′

,n)</sup>(f) is the microscopic phase difference.

27. The method according to claim 26, wherein Δ

_mm′

⁽ⁿ⁾ is approximated by the term;

28. The method according to claim 17, further comprising applying the delay profile in the frequency domain by de-rotating the phase of the transmitted signal from the antenna units.

29. The method according to claim 28, wherein the delay profile is applied as a pure time shift or in the alternative as a cyclic time shift.

30. The method according to claim 17, further comprising applying the delay profile in the time domain.

31. An apparatus configured to connect to a communication link for establishing communication to a plurality of antenna units that are spatially separated and that wirelessly communicate with at least a first terminal, each terminal having a terminal antenna, the apparatus comprising a controller unit and a storage unit, the storage unit storing computer software that when executed by the controller unit controls the apparatus to compensate for propagation delay in a wireless communication system based on configuring the apparatus to:

determine propagation delay from each of the first plurality of antenna units to the terminal antenna of said first terminal,

establish a delay profile specific for each targeted terminal using the determined propagation delay, and

compensating for the determined relative propagation delay from each antenna unit to said first terminal by applying the delay profile to a transmission between the processing unit and said first terminal.

32. The apparatus according to claim 31, wherein the transmission is from the apparatus to said first terminal or from said first terminal to the apparatus.

33. The apparatus according to claim 31, wherein one of the first plurality of antenna units uses a multitude of antennas.

34. The apparatus according to claim 31, wherein the apparatus is a base station or a Node B.

35. The apparatus according to claim 31, wherein said first terminal uses a plurality of antennas.

36. The apparatus according to claim 31, wherein the apparatus is in communication with a third plurality of terminals.

37. The apparatus according to claim 31, wherein the relative propagation delay between each of the first plurality of antenna units and said first terminal or between each of the first plurality of antenna units and each of a second plurality of terminals are determined in the frequency domain, and wherein the storage unit stores computer software that when executed by the controller unit further controls the apparatus to:

evaluate phase differences between propagation channels between said first terminal and multiple antenna units, or between a terminal in the second plurality of terminals and multiple antenna units, for two different frequencies; and

estimate propagation time differences from the slope of one line being fitted to the evaluated phase differences over frequency.

38. The apparatus according to claim 37, wherein phase differences are evaluated for a fourth plurality of frequencies.

39. The apparatus according to claim 37, wherein each propagation time difference is estimated from a fifth plurality of fitted lines, with one or a sixth plurality of slopes.

40. The apparatus according to claim 31, wherein the propagation delay between each of the first plurality of antenna units and said first terminal or each of a second plurality of terminals are determined using the equation:

Θ

_kl^(m,n)(f)−

Θ

<sub>k′

l</sub><sup>(m′

,n)</sup>(f)=φ

_kl^(m,n)(f)−

φ

<sub>k′

l</sub><sup>(m′

,n)</sup>(f)+Δ

_mm′

⁽ⁿ⁾f,

wherein Δ

_mm′

⁽ⁿ⁾=τ

^(m,n)−

τ

<sup>(m′

,n)</sup> is an estimate of the time difference between signals from the n'"'"'th terminal arriving at antenna units m and m′

of the first plurality of antenna units, τ

^(m,n) is the time difference induced by the propagation channel between the processing unit and the second plurality of antennas of terminal n, Θ

_kl^(m,n)(f)−

Θ

<sub>k′

l</sub><sup>(m′

,n)</sup>(f) is an estimate of phase difference of two channels, and φ

_kl^(m,n)(f)−

φ

<sub>k′

l</sub><sup>(m′

,n)</sup>(f) is the microscopic phase difference.

41. The apparatus according to claim 31, wherein the storage unit stores computer software that when executed by the controller unit controls the apparatus to apply the delay profile in the frequency domain by de-rotating the phase of the transmitted signal from the antenna units.

42. The apparatus according to claim 41, wherein the delay profile is applied as a pure time shift or in the alternative as a cyclic time shift.

43. The apparatus according to claim 31, wherein the storage unit stores computer software that when executed by the controller unit controls the apparatus to apply the delay profile in the time domain.