Power control with signal quality estimation for smart antenna communication systems

• US 6,463,295 B1
• Filed: 02/06/1998
• Issued: 10/08/2002
• Est. Priority Date: 10/11/1996
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: ArrayComm LLC (Ygomi LLC)
• Inventors: Yun, Louis C.
• Primary Examiner(s): Le, Thanh Cong
• Assistant Examiner(s): LE, LANA N
• Application Number:
  US09/020,049
• Time in Patent Office: 1,705 Days
• Field of Search: 455/422, 455/522, 455/69, 455/562, 455/63, 455/560, 455/517, 370/277, 370/334
• US Class Current: 455/522
• CPC Class Codes: H04B 17/336 Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity
• CPC Class Codes: H04W 52/50 at the moment of starting communication in a multiple access environment
• CPC Class Codes: H04W 72/00 Local resource management
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 76/10 Connection setup

Abstract

A method for ongoing power control for a communication station with a multiple antenna array, the power control using a method for signal quality estimation applicable for angle modulated signals. One aspect of the ongoing power control method is applicable for the uplink and includes separating the joint determination of a receive weight vector and ongoing power control into a receive weight vector determining part and a separate transmit power adjustment part. In one embodiments, The ongoing power control method for the downlink includes separating the joint determination of a receive weight vector and ongoing power control into a receive weight vector determining part and a separate transmit power adjustment part. The method starts with one part, for example transmit power assignment. Receive weight vector determination is carried out with this assigned transmit power and the new weights used. An estimate of the resulting received signal quality is obtained and used for new ongoing power adjustment. Another aspect is applicable for the downlink and includes one aspect of the ongoing power control method is applicable for the uplink and includes separating the determination of a complete transmit weight vector including the vector of relative transmit weights and the scaling to use with the relative transmit weights into a part for determining a set of relative transmit weights and a separate transmit power adjustment part that determines the scaling factor.

Claims

1. A method for ongoing power control for uplink communications between one or more remote transmitters and a communication station for receiving an uplink signal, the communication station including an array of antenna elements, each antenna element coupled to an associated receive apparatus, and a processor for spatial processing the set of signals from the set of receive apparatuses, the spatial processing forming the uplink signal according to a receive weight vector of receive weights, the method comprising, for a particular remote transmitter

(a) setting up an initial power assignment for the particular remote transmitter on a conventional channel and transmitting a particular uplink signal from the particular remote transmitter on the conventional channel;

(b) determining a particular receive weight vector for communicating with the particular remote transmitter on a spatial channel of the conventional channel;

(c) receiving the particular uplink signal at the antenna elements and associated receive apparatuses as a set of received signals and spatially processing the received signals with the particular receive weight vector to form a particular received signal;

(d) estimating the quality of the particular received signal;

(e) determining an updated power assignment for the particular remote transmitter, the power assignment determination using the received signal quality estimate; and

(f) applying the updated power assignment at the particular remote transmitter, the applying including transmitting a new uplink signal.

2. The method of claim 1 further including periodically repeating at least steps (c), (d), (e) and (f) of the set consisting of steps (b), (c), (d), (e) and (f).

3. The method of claim 2 wherein the determining step (e) is carried out in the communication station and applying step (f) includes communicating the updated power assignment to the remote transmitter.

4. The method of claim 2 wherein the received signal quality estimate is a SINR estimate.

5. The method of claim 4,

wherein the communication station is included in a communication system of one or more cells, each cell including a particular communication station and its particular set of corresponding remote transmitters, and

wherein the updated power assignment of step (e) is determined independently at each distinct cell of the communications system, such independent determining being without any power control information communicated from any other cell of the communication system.

6. The method of claim 4 wherein the power assignment determined in a repetition of step (e) for the particular remote transmitter is a function of a target SINR, the powers used in previous repetitions of step (f) for transmitting from the particular remote transmitter, and SINR estimates from the present and prior repetitions of estimating step (d).

7. The method of claim 6 wherein the function is of the target SINR, the SINR estimate from the most recent application of step (d), and the most recent application of power assignment applying step (f).

8. The method of claim 7 wherein, when all powers and SINR quantities are expressed in logarithmic scale, the function is defined by the difference between the power determined in the repetition of step (e) and the power applied in the most recent application of step (f) having a relationship to the difference between the SINR estimate from the most recently applied step (d) and the target SINR.

9. The method of claim 7, wherein the relationship is proportionality.

10. The method of claim 7, wherein the target SINRs all have the same value for all the uplink spatial channels of the conventional channel.

11. The method of claim 2 wherein the determining step (e) is subject to the constraint of a predicted uplink signal quality measure being at least a target uplink signal quality.

12. The method of claim 11 wherein the received signal quality estimate is a SINR estimate, the predicted uplink signal quality measure is a predicted SINR measure dependent on the SINR estimate, and the target signal quality is a target SINR.

13. The method of claim 12

wherein the communication station is included in a communication system of one or more cells, each cell including a particular communication station and its particular set of corresponding remote transmitters, and

wherein the updated power assignment of step (e) is determined independently at each distinct cell of the communications system, such independent determining being without any power control information communicated from any other cell of the communication system.

14. The method of claim 13 wherein in each repetition, the power assignments determined in all steps (e) for uplink communications for all the uplink spatial channels of the conventional channel are those that minimize a weighted sum of the powers to transmit on the uplink spatial channels of the conventional channel.

15. The method of claim 14 wherein the weighted sum is the total of the powers to transmit on the uplink spatial channels of the conventional channel.

16. The method of claim 14 wherein the predicted uplink SINR measure for the spatial channel is an expression of the particular receive weight vector, an expression uplink path losses for the spatial channel and for other uplink spatial channels of the conventional channel, the receive spatial signature of the particular remote transmitter, the receive spatial signatures of the other remote transmitters on the conventional channel, and the post-spatial processing noise-plus-intercell interference experienced by the communication station on the spatial channel, the path loss for the spatial channel being a function of the estimated SINR and of the most recently used transmit power, the intercell interference plus noise for any uplink spatial channel is a functions of the SINR estimate for that uplink spatial channel, the receive weight vectors and the receive spatial signatures for all remote transmitters on the uplink spatial channels of the conventional channel, the powers applied by the remote transmitters in the most recent repetition of step (f) all the uplink spatial channels of the conventional channel, and the path losses for the spatial channel and for the other uplink spatial channels of the conventional channel.

17. The method of claim 16 wherein the particular constraint for the spatial channel, the spatial channel denoted by subscript i, the total number of uplink spatial channels in the conventional channel denoted by d, the target SINR for the uplink spatial channel denoted by SINR_targeti^U, is mathematically expressed as $\frac{L_i^U}{}$



wiU*

aiU

2

piU∑

j≠

i,j=1d

LjU



wiU*

aj

2

pjU+IiU≥

SINRtargetiU

where, for j=1, . . . , d, p_j^U is the power for transmitting in the next application of step (f) on uplink spatial channel j from the remote transmitter on spatial channel j to the communication station, L_j^U is the path loss on uplink spatial channel j from the remote transmitter on spatial channel j to the communication station, w_j^U is the receive weight vector for receiving j from the remote transmitter on spatial channel j, the receive weight vector having a Euclidean norm of 1, a_j^U is the receive spatial signature of the remote transmitter on uplink spatial channel j, the receive spatial signatures each having Euclidean norm 1, and I_j^U is the uplink post-spatial processing noise-plus-intercell interference experienced by the communication station on uplink spatial channel j.

18. The method of claim 14, wherein the target SINRs all have the same value for all the uplink spatial channels of the conventional channel.

19. The method of claim 13 wherein the constraint is that the predicted SINR measure is equal to the target SINR.

20. The method of claim 19 wherein the predicted uplink SINR measure for the spatial channel is an expression of the particular receive weight vector, the other receive weight vectors used for communication on the other uplink spatial channels of the conventional channel, an expression uplink path losses for the spatial channel and for other uplink spatial channels of the conventional channel, the receive spatial signature of the particular remote transmitter, the receive spatial signatures of the other remote transmitters on the conventional channel, and the post-spatial processing noise-plus-intercell interference experienced by the communication station on the spatial channel, the path loss for the spatial channel being a function of the estimated SINR and of the most recently used transmit power, the intercell interference plus noise for any uplink spatial channel is a functions of the SINR estimate for that uplink spatial channel, the receive weight vectors and the receive spatial signatures for all remote transmitters on the uplink spatial channels of the conventional channel, the powers applied by the remote transmitters in the most recent repetition of step (f) all the uplink spatial channels of the conventional channel, and the uplink path losses for the spatial channel and for the other uplink spatial channels of the conventional channel.

21. A method for ongoing power control for downlink communications between a communication station for transmitting a downlink signal and one or more remote receivers, the communication station including an array of antenna elements for transmitting a set of transmit signals through a set of antenna transmit apparatuses, each associated with one of the antenna elements, and a processor for spatial processing the downlink signal according to a transmit weight vector of transmit weights to form the set of transmit signals, the method comprising, for a particular remote receiver:

(a) setting up an initial power assignment for the communication station for transmitting to the particular remote receiver using an initial transmit weight vector on a spatial channel of a conventional channel and transmitting a particular downlink signal from the communication station on the spatial channel according to the initial transmit weight vector and the initial power assignment;

(b) receiving the particular downlink signal at the remote receiver;

(c) estimating the quality of the received downlink signal;

(d) determining an updated power assignment for the communication station for transmitting to the particular remote receiver, the power assignment determination using the received signal quality estimate; and

(e) applying the updated power assignment at the communication station, the applying including transmitting a new downlink signal.

22. The method of claim 21 further including

(f) determining an updated transmit weight vector for transmitting from the communications station to the particular remote receiver on the spatial channel, the transmitting the new downlink signal in step (e) using the updated transmit weight vector.

23. The method of claim 22 wherein the new downlink signal is the same as the most recent downlink signal transmitted to the particular remote transmitter on the spatial channel.

24. The method of claim 22 further including periodically repeating at least steps (b), (c), (d), and (e) of the set consisting of steps (b), (c), (d), (e) and (f).

25. The method of claim 24 wherein the received signal quality estimate is a SINR estimate.

26. The method of claim 25 wherein the SINR estimate is determined at the remote receiver and applying step (d) includes communicating the SINR estimate to the communication station.

27. The method of claim 25,

wherein the communication station is included in a communication system of one or more cells, each cell including a particular communication station and its particular set of corresponding remote receivers, and

wherein the updated power assignment of step (d) is determined independently at each distinct cell of the communications system, such independent determining being without any power control information communicated from any other cell of the communication system.

28. The method of claim 27 wherein the power assignment determined in a repetition of step (d) for the particular remote receiver is a function of a target SINR, the powers used in previous repetitions of step (e) for transmitting to the particular remote receiver, and SINR estimates from the present and prior repetitions of estimating step (c).

29. The method of claim 28 wherein the function is of the target SINR, the SINR estimate from the most recent application of step (c), and the most recent application of power assignment applying step (e).

30. The method of claim 29 wherein, when all powers and SINR quantities are expressed in logarithmic scale, the function is defined by the difference between the power determined in the repetition of step (d) and the power applied in the most recent application of step (e) having a relationship to the difference between the SINR estimate from the most recently applied step (c) and the target SINR.

31. The method of claim 30, wherein the relationship is proportionality.

32. The method of claim 30, wherein the target SINRs all have the same value for all the downlink spatial channels of the conventional channel.

33. The method of claim 22 wherein the particular remote receiver includes a remote transmitter for transmitting on an uplink spatial channel of a second conventional channel, the communications station includes a set of receive apparatuses, each coupled to one of the antenna elements, a receive processor for spatially processing the signals received by the set of receive apparatuses into an uplink signal according to a receive weight vector, the updated transmit weight vector determined in step (f) is determined from the signals received by the set of receive apparatuses at the communication station as a result of the remote transmitter transmitting a particular uplink signal.

34. The method of claim 33 wherein the conventional channel and the second conventional channel use the same frequency for communicating.

35. The method of claim 34 wherein the updated transmit weight vector is determined in step (f) is determined from the receive weight vector used by the second processor for determining a received version of the particular uplink signal.

36. The method of claim 21 further including periodically repeating steps (b), (c), (d), and (e).

37. The method of claim 36 wherein the determining step (d) is subject to the constraint of a predicted downlink signal quality measure being at least a target downlink signal quality.

38. The method of claim 37 wherein the received signal quality estimate is a SINR estimate, the predicted downlink signal quality measure is a predicted SINR measure dependent on the SINR estimate, and the target signal quality is a target SINR.

39. The method of claim 38,

wherein the communication station is included in a communication system of one or more cells, each cell including a particular communication station and its particular set of corresponding remote receivers, and

wherein the updated power assignment of step (d) is determined independently at each distinct cell of the communications system, such independent determining being without any power control information communicated from any other cell of the communication system.

40. The method of claim 39 wherein in each repetition, the power assignments determined in all steps (d) for downlink communications for all the downlink spatial channels on the conventional channel are those that minimize a weighted sum of the powers to transmit on the downlink spatial channels of the conventional channel.

41. The method of claim 40 wherein the weighted sum is the total of the powers to transmit on the downlink spatial channels of the conventional channel.

42. The method of claim 40 wherein the predicted downlink SINR measure for the spatial channel is an expression of the most recently updated transmit weight vector for the particular remote receiver, the other receive weight vectors used for communication on the other downlink spatial channels of the conventional channel, an expression downlink path losses for the spatial channel and for other uplink spatial channels of the conventional channel, the transmit spatial signature of the particular remote receiver, and the post-spatial processing noise-plus-intercell interference experienced by the remote receiver on the spatial channel, the path loss for the spatial channel being a function of the estimated SINR and of the most recently used transmit power. the intercell interference plus noise for any downlink spatial channel is a functions of the SINR estimate for that downlink spatial channel, the transmit weight vectors and the transmit spatial signatures for all remote receivers on the downlink spatial channels of the conventional channel, the powers applied by the communication station in the most recent repetition of step (e) all the downlink spatial channels of the conventional channel, and the downlink path losses for the spatial channel and for the other downlink spatial channels of the conventional channel.

43. The method of claim 42 wherein the particular constraint for the spatial channel, the spatial channel denoted by subscript i, the total number of downlink spatial channels on the conventional channel denoted by d, the target SINR for the downlink spatial channel denoted by SINR_targeti^D, is mathematically expressed as $\frac{L_i^D}{}$



wiD*

aiD

2

piD∑

j≠

i,j=1d

LiD



wjD*

ai

2

pjD+IiD≥

SINRtargetiD

where, for j=1, . . . , d, p_j^D is the power for transmitting in the next application of step (e) on downlink spatial channel j from the communication station to the remote receiver on spatial channel j, L_j^D is the path loss on downlink spatial channel j from the communication station on spatial channel j to the remote receiver on spatial channel j, w_j^D is the transmit weight vector for transmitting to the remote receiver on spatial channel j, each transmit weight vector having a Euclidean norm of 1, a_j^D is the transmit spatial signature of the remote receiver on downlink spatial channel j, the transmit spatial signatures having a Euclidean norm of 1, and I_j^D is the downlink post-spatial processing noise-plus-intercell interference experienced by the remote receiver on downlink spatial channel j.

44. The method of claim 40 wherein the target SINRs all have the same value for all the downlink spatial channels of the conventional channel.

45. The method of claim 39 wherein the constraint is that the predicted SINR measure is equal to the target SINR.

46. The method of claim 45 wherein the predicted downlink SINR measure for the spatial channel is an expression of the particular transmit weight vector, the other transmit weight vectors used for communication on the other downlink spatial channels of the conventional channel, an expression downlink path losses for the spatial channel and for other downlink spatial channels of the conventional channel, the transmit spatial signature of the particular remote receiver, the transmit spatial signatures of the other remote receivers on the conventional channel, and the post-spatial processing noise-plus-intercell interference experienced by the particular remote receiver on the spatial channel, the path loss for the spatial channel being a function of the estimated SINR and of the most recently used transmit power, the intercell interference plus noise for any downlink spatial channel is a functions of the SINR estimate for that downlink spatial channel, the transmit weight vectors and the transmit spatial signatures for all remote receivers on the downlink spatial channels of the conventional channel, the powers applied by the communication station in the most recent repetition of step (e) for all the downlink spatial channels of the conventional channel, and the path losses for the spatial channel and for the other downlink spatial channels of the conventional channel.

47. A method for global ongoing power control in a communication system, the communication system including a set of one or more communication stations, each communication station communicates on the uplink with a set of one or more corresponding remote transmitters and on the downlink with a set of one or more corresponding remote receivers co-located with the corresponding remote transmitters, each communication station comprising an array of receiving antenna elements, a set of receive apparatuses, each antenna element coupled to one of the receive apparatuses, a receive spatial processor, the outputs of the receive apparatuses coupled to the spatial processor for spatial processing received signals according to a receive weight vector, uplink communication with any corresponding remote transmitter being according to the receive weight vector for that remote transmitter, each communication station also including a transmit spatial processor for forming a set of transmit antenna signals according to a transmit weight vector, a set of transmit apparatuses, each transmit apparatus accepting one of the transmit antenna signals, and an array of transmitting antenna elements, each coupled to the output of one of the transmit apparatuses, downlink communication with any corresponding remote receiver being according to the transmit weight vector for that remote receiver, the method comprising:

(a) for each communication station and for each corresponding remote transmitter of the communication station transmitting to the communication station on a spatial uplink channel of a conventional uplink channel of the communication station;

(i) transmitting a particular uplink signal from the remote transmitter on the conventional uplink channel, the transmitting according to an initial uplink power assignment;

(ii) determining a particular receive weight vector for communicating with the particular remote transmitter on the spatial uplink channel of the conventional uplink channel;

(iii) receiving the particular uplink signal at the antenna elements and associated receive apparatuses as a set of received signals and spatially processing the received signals with the particular receive weight vector to form a particular received uplink signal;

(iv) estimating the quality of the particular received uplink signal;

(v) determining an updated uplink power assignment for the remote transmitter, the uplink power assignment determination using the received uplink signal quality estimate, the determining subject to the constraint of a predicted uplink signal quality measure being at least a target uplink signal quality; and

(vi) applying the updated uplink power assignment at the particular remote transmitter, the applying including transmitting a new uplink signal, all the updated uplink power assignments in all steps (a)(v) determined as those powers that simultaneously minimizing the weighted sum of transmit powers used for transmitting to all communications stations from all of the corresponding remote transmitters, and

(b) for each communication station and for each corresponding remote receiver of the communication station receiving from the communication station on a spatial downlink channel of a conventional downlink channel of the communication station

(i) transmitting a particular downlink signal from the communication station to the remote transmitter on the spatial channel according to an initial transmit weight vector for the remote transmitter and according to an initial downlink power assignment;

(ii) receiving the particular downlink signal at the remote receiver;

(iii) estimating the quality of the received downlink signal;

(iv) determining an updated downlink power assignment for the communication station for transmitting to the remote receiver, the downlink power assignment determination using the received downlink signal quality estimate, the determining subject to the constraint of a predicted downlink signal quality measure being at least a target downlink signal quality; and

(v) applying the updated downlink power assignment at the communication station, the applying including transmitting a new downlink signal, all the updated downlink power assignments in all steps (b)(iv) determined as those powers that simultaneously minimize the weighted sum of transmit powers used for transmitting from all communications stations to all of the corresponding remote transmitters.

48. The method of claim 47 wherein the predicted downlink signal quality measure in step (a)(v) is determined independently at each distinct cell of the communications system and the predicted uplink signal quality measure in step (b)(iv) is determined independently at each distinct cell of the communications system, a cell consisting of a particular communication station and the particular communication station'"'"'s set of corresponding remote transmitters and remote receivers, such independent determining being without information communicated from any other cell of the communication system.

49. A method for ongoing uplink power control and receive weight vector determination for uplink communications between one or more remote transmitters and a communication station for receiving an uplink signal, the communication station including an array of antenna elements, each antenna element coupled to an associated receive apparatus, and a processor for spatial processing the outputs of the set of receive apparatuses, the spatial processing forming the uplink signal according to a receive weight vector of receive weights, the method comprising:

for a particular remote transmitter,

(a) determining a particular receive weight vector for communicating with the particular remote transmitter on a spatial channel of a conventional channel; and

(b) separately determining a power assignment for the particular remote transmitter for transmitting to the communication station on the spatial channel.

50. The method of claim 49 further comprising periodically iterating back and forth between step (a) of particular receive weight vector determining and step (b) of power assignment determining.

51. A method for complete transmit weight vector determining for downlink communications between a communication station and one or more remote receivers for transmitting a downlink signal, the communication station including an array of antenna elements, each antenna element coupled to the output of an associated transmit apparatus, and a processor for spatial processing a downlink signal into a set of transmit signals each coupled to an input of one of the transmit apparatuses, the spatial processing forming the transmit signals according to a complete transmit weight vector, the complete transmit weight vector comprising a relative transmit weight vector of relative transmit weights and a scaling factor applied as a power assignment for use with the relative transmit weight vector, the method comprising:

for a particular remote receiver,

(a) determining a particular relative transmit weight vector for transmitting from the communication station to the particular remote receiver on a spatial channel of a conventional channel; and

(b) separately determining a power assignment for transmitting to the particular remote receiver on the spatial channel, the power assignment forming the scaling factor to use with the particular relative transmit weight vector.

52. The method of claim 51 further comprising:

(c) periodically repeating step (a) of particular relative transmit weight vector determining; and

(d) periodically repeating step (b) of power assignment determining.