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