Method and system for determining uplink/downlink path-loss difference

• US 20050143118A1
• Filed: 08/26/2004
• Published: 06/30/2005
• Est. Priority Date: 11/25/2003
• Status: Active Grant

• Current Assignee: Optis Wireless Technology, LLC (Brevet Capital)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Bernhardsson, Bo, Ohlsson, Jonas, Ziren, Mikael
• Granted Patent: US 7,302,276 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04B 17/327 Received signal code power [RSCP]
• CPC Class Codes: H04W 52/14 Separate analysis of uplink or downlink
• CPC Class Codes: H04W 52/228 using past power values or information
• CPC Class Codes: H04W 52/242 taking into account path loss
• CPC Class Codes: H04W 52/245 taking into account received signal strength
• CPC Class Codes: H04W 52/246 where the output power of a terminal is based on a path parameter calculated in said terminal
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment

Abstract

Methods and apparatus are described for estimating a path-loss difference between uplink and downlink communications at a first node communicating with a second node in a communication system. A quantity of access request preambles transmitted by the first node to the second node before an acknowledgement from the second node of successful receipt of a preamble is received at the first node is determined. A difference between an uplink path-loss attributed to communications from the first node to the second node and a downlink path-loss attributed to communications to the first node from the second node is estimated based on the transmitted preamble quantity determination. Once the path-loss difference is estimated, the estimate can be used for many purposes, such as to determine a transmission power of the first node.

Claims

1. A method for estimating a path-loss difference between uplink and downlink communications at a first node communicating with a second node in a communication system, comprising:

determining, at the first node, a quantity of access request preambles transmitted by the first node to the second node before an acknowledgement from the second node of successful receipt of a preamble is received at the first node, the preambles being transmitted at incrementally increasing power levels;

estimating, at the first node, a difference between an uplink path-loss attributed to communications from the first node to the second node and a downlink path-loss attributed to communications to the first node from the second node based on the transmitted preamble quantity determination.

2. The method of claim 1, comprising:

determining a transmission power of the first node based on the estimated path-loss difference.

3. The method of claim 1, wherein estimating the path-loss difference comprises:

comparing the transmitted preamble quantity determination to a threshold value; and

estimating the path-loss difference based on the comparison.

4. The method of claim 1, wherein estimating the path-loss difference comprises:

comparing the transmitted preamble quantity determination to a quantity range; and

estimating the path-loss difference based on the comparison.

5. The method of claim 4, wherein estimating the path-loss difference based on the comparison comprises:

increasing the path-loss estimate when the transmitted preamble quantity is above the quantity range; and

decreasing the path-loss estimate when the transmitted preamble quantity is below the quantity range.

6. The method of claim 1, wherein estimating the path-loss difference comprises:

comparing the transmitted preamble quantity determination to a threshold value; and

adjusting a previous path-loss difference estimation based on the comparison.

7. The method of claim 1, wherein estimating the path-loss difference comprises:

comparing the transmitted preamble quantity determination to a quantity range; and

adjusting a previous path-loss difference estimation based on the comparison.

8. The method of claim 1, wherein estimating the path-loss difference comprises:

limiting the path-loss difference determination to within a range of allowable values.

9. The method of claim 2, wherein determining a transmission power of the first node comprises:

estimating, at the first node, a received signal strength of a signal transmitted by the second node;

adjusting the estimated received signal strength according to the path-loss difference estimation; and

determining the transmission power based on the adjusted received signal strength.

10. The method of claim 9, wherein the received signal strength is based on a received signal code power (RSCP).

11. The method of claim 1, wherein the access request preambles are part of a random access channel (RACH) procedure.

12. The method of claim 1, wherein the first node is part of at least one of a mobile phone, a personal digital assistant, a pager, a portable computer, and a modem card in a machine to machine application.

13. The method of claim 2, wherein the determined transmission power level is used as a power level for an initial one of a next quantity of access request preambles.

14. The method of claim 3, wherein the threshold value is provided to the first node via the communication system.

15. The method of claim 6, wherein the threshold value is provided to the first node via the communication system.

16. The method of claim 3, wherein the threshold value changes dynamically.

17. The method of claim 6, wherein the threshold value changes dynamically.

18. An apparatus for determining a path-loss difference between uplink and downlink communications within a first node communicating with a second node in a communication system, the apparatus comprising:

logic that determines a quantity of access request preambles transmitted by the first node to the second node before an acknowledgment from the second node of successful receipt of a preamble is received at the first node, the preambles being transmitted at incrementally increasing power levels;

logic that estimates a difference between an uplink path-loss attributed to communications from the first node to the second node and a downlink path-loss attributed to communications to the first node from the second node based on the transmitted preamble quantity determination.

19. The apparatus of claim 18, comprising:

logic that determines a transmission power of the first node based on the estimated path-loss difference.

20. The apparatus of claim 18, comprising:

logic that compares the transmitted preamble quantity determination to a threshold value; and

logic that estimates the path-loss difference based on the comparison.

21. The apparatus of claim 18, comprising:

logic that compares the transmitted preamble quantity determination to a quantity range; and

logic that estimates the path-loss difference based on the comparison.

22. The apparatus of claim 21, comprising:

logic that increases the path-loss estimate when the transmitted preamble quantity is above the quantity range; and

logic that decreases the path-loss estimate when the transmitted preamble quantity is below the quantity range.

23. The apparatus of claim 21, comprising:

logic that compares the transmitted preamble quantity determination to a threshold value; and

logic that adjusts a previous path-loss difference estimation based on the comparison.

24. The apparatus of claim 21, comprising:

logic that compares the transmitted preamble quantity determination to a quantity range; and

logic that adjusts a previous path-loss difference estimation based on the comparison.

25. The apparatus of claim 18, comprising:

logic that limits the path-loss difference determination to within a range of allowable values.

26. The apparatus of claim 19, comprising:

logic that estimates, at the first node, a received signal strength of a signal transmitted by the second node;

logic that adjusts the estimated received signal strength according to the path-loss difference estimation; and

logic that determines the transmission power based on the adjusted received signal strength.

27. The apparatus of claim 26, wherein the received signal strength is based on a received signal code power (RSCP).

28. The apparatus of claim 18, wherein the access request preambles are part of a random access channel (RACH) procedure.

29. The apparatus of claim 18, wherein the first node is part of at least one of a mobile phone, a personal digital assistant, a pager, a portable computer, and a modem card in a machine to machine application.

30. The apparatus of claim 19, wherein the determined transmission power level is used as a power level for an initial one of a next quantity of access request preambles.

31. The apparatus of claim 20, wherein the threshold value is provided to the first node via the communication system.

32. The apparatus of claim 23, wherein the threshold value is provided to the first node via the communication system.

33. The apparatus of claim 20, wherein the threshold value changes dynamically.

34. The apparatus of claim 23, wherein the threshold value changes dynamically.

35. An apparatus for determining a path-loss difference between uplink and downlink communications within a first node communicating with a second node in a communication system, the apparatus comprising:

means for determining a quantity of access request preambles transmitted by the first node to the second node before an acknowledgement from the second node of successful receipt of a preamble is received at the first node, the preambles being transmitted at incrementally increasing power levels;

means for comparing the determining quantity of access request preambles to a reference; and

means for estimating a difference between an uplink path-loss attributed to communications from the first node to the second node and a downlink path-loss attributed to communications to the first node from the second node based on the comparison.

36. The apparatus of claim 35, comprising:

means for setting a power transmission level based on the estimated path-loss difference.

37. The apparatus of claim 36, wherein the means for setting a power transmission level comprises:

means for estimating a received signal strength; and

means for setting the power transmission level based on the estimated path-loss difference and the estimated received signal strength.

38. The apparatus of claim 35, wherein the apparatus is part of at least one of a mobile phone, a personal digital assistant, a pager, and a portable computer.

39. A computer-readable medium containing a computer program for estimating a path-loss difference between uplink and downlink communications at a first node communicating with a second node in a communication system, wherein the computer program performs the steps of:

determining, at the first node, a quantity of access request preambles transmitted by the first node to the second node before an acknowledgement from the second node of successful receipt of a preamble is received at the first node, the preambles being transmitted at incrementally increasing power levels;

estimating, at the first node, a difference between an uplink path-loss attributed to communications from the first node to the second node and a downlink path-loss attributed to communications to the first node from the second node based on the transmitted preamble quantity determination.

40. The computer-readable medium of claim 39, wherein to estimate the path-loss difference, the computer program performs the steps of:

comparing the transmitted preamble quantity determination to a quantity range; and

adjusting a previous path-loss difference estimation based on the comparison.