Systems, apparatus and methods for physical random access channel processing

• US 8,265,642 B2
• Filed: 06/15/2010
• Issued: 09/11/2012
• Est. Priority Date: 06/16/2009
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Zhang, Xiaoxia, Malladi, Durga Prasad, Wei, Yongbin, Xu, Hao, Luo, Tao
• Primary Examiner(s): Patel, Ajit
• Application Number:
  US12/816,305
• Publication Number:
  US 20110143762A1
• Time in Patent Office: 819 Days
• Field of Search: None
• US Class Current: 455/450
• CPC Class Codes: H04W 74/002 Transmission of channel access control information
• CPC Class Codes: H04W 74/004 in the uplink, i.e. towards network
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access

Abstract

Systems and methods for processing a physical random access channel are provided. In some embodiments, a method can include: receiving a signal indicative of a strong user and a desired user on a physical random access channel; performing at least one of a single segment frequency domain detection or a multi-segment frequency domain detection on the signal indicative of a strong user and a desired user; generating a residual signal by cancelling out the signal indicative of a strong user; and obtaining a message transmitted by a user equipment by performing at least one of the single segment frequency domain detection or multi-segment frequency domain detection on the residual signal.

Claims

1. A method for facilitating physical random access channel processing, the method comprising:

receiving a signal indicative of a strong user and a desired user on a physical random access channel;

performing at least one of a single segment frequency domain detection or a multi-segment frequency domain detection on the signal indicative of a strong user and a desired user;

generating a residual signal by cancelling out the signal indicative of a strong user; and

obtaining a message transmitted by a user equipment by performing at least one of the single segment frequency domain detection or multi-segment frequency domain detection on the residual signal.

2. The method of claim 1, wherein the message is a random access message received on the physical random access channel.

3. The method of claim 2, wherein the physical random access channel is received on a set of resources such that the physical random access channel for a first base station interferes with a physical random access channel for a second base station.

4. The method of claim 3, wherein the second base station is an access point.

5. The method of claim 3, wherein the first base station is associated with at least one of a pico cell or a Femto cell, and wherein the second base station is associated with a macro cell.

6. The method of claim 4, wherein a time duration of a physical random access channel for a second base station overlaps with and is a subset of a time duration of a physical random access channel for a first base station.

7. The method of claim 4, further comprising receiving one or more parameters related to transmission of the physical random access channel to the access point, and selecting resources for receiving the physical random access channel at the first base station based, at least, on the one or more parameters related to transmission of the physical random access channel to the access point.

8. The method of claim 7, wherein the one or more parameters are received over a backhaul communicatively coupled between the first base station and an access point.

9. The method of claim 7, wherein the one or more parameters are determined by receiving, over-the-air, a system information block transmitted from the access point.

10. The method of claim 1, wherein frequency domain detection is single segment frequency domain detection, the method further comprising:

performing a cyclic cross-correlation with a local replica of a random access sequence;

determining a random access channel signal at a selected antenna of a base station, wherein the base station is configured to perform the determining;

performing a segment correlation for a selected root associated with the random access sequence; and

performing cyclic cross correlation for each root sequence associated with the random access sequence.

11. The method of claim 10, wherein the generating a residual signal by cancelling out the signal indicative of a strong user comprises:

determining a plurality of channel estimates for the strong user;

performing a frequency transformation on the plurality of channel estimates for the strong user to obtain a channel frequency response per antenna of the base station;

obtaining a frequency domain product, wherein the frequency domain product is a product of a channel frequency response and a result of performing the single segment frequency domain detection on the signal indicative of a strong user and a desired user, wherein the channel frequency response is based, at least, on the plurality of channel estimates for the strong user; and

generating the residual signal by subtracting the frequency domain product from the single segment frequency domain detection on the signal indicative of a strong user and a desired user.

12. The method of claim 1, wherein frequency domain detection is multi-segment frequency domain detection, the method further comprising:

dividing the signal indicative of a strong user and a desired user on a physical random access channel into multiple segments;

performing frequency domain matching on zero padded versions of the multiple segments;

performing circular correlation via frequency domain multiplication;

estimating channel estimates per segment, and generating a channel frequency response per segment;

obtaining a plurality of frequency domain products, wherein the plurality of frequency domain products are products of channel frequency responses and results of performing the multi-segment frequency domain detection on multiple segments of the signal indicative of a strong user and a desired user, wherein each of the channel frequency responses are based, at least, on a plurality of channel estimates for the strong user; and

generating residual signals by subtracting the plurality of frequency domain products from respective multi-segment frequency domain detection on multiple segments of the signal indicative of a strong user and a desired user.

13. A computer program product, comprising:

a non-transitory computer-readable medium, comprising;

a first set of codes for causing a computer to receive a signal indicative of a strong user and a desired user on a physical random access channel;

a second set of codes for causing the computer to perform at least one of a single segment frequency domain detection or a multi-segment frequency domain detection on the signal indicative of a strong user and a desired user;

a third set of codes for causing the computer to generate a residual signal by cancelling out the signal indicative of a strong user; and

a fourth set of codes for causing the computer to obtain a message transmitted by a user equipment by performing at least one of the single segment frequency domain detection or multi-segment frequency domain detection on the residual signal.

14. The computer program product of claim 13, wherein the message is a random access message received on the physical random access channel.

15. The computer program product of claim 14, wherein the physical random access channel is received on a set of resources such that the physical random access channel for a first base station interferes with a physical random access channel for a second base station.

16. The computer program product of claim 15, wherein the second base station is an access point.

17. The computer program product of claim 15, wherein the first base station is associated with at least one of a pico cell or a Femto cell, and wherein the second base station is associated with a macro cell.

18. The computer program product of claim 16, wherein a time duration of a physical random access channel for a second base station overlaps with and is a subset of a time duration of a physical random access channel for a first base station.

19. The computer program product of claim 16, further comprising a fifth set of codes for causing the computer to receive one or more parameters related to transmission of the physical random access channel to the access point, and selecting resources for receiving the physical random access channel at the first base station based, at least, on the one or more parameters related to transmission of the physical random access channel to the access point.

20. The computer program product of claim 19, wherein the one or more parameters are received over a backhaul communicatively coupled between the first base station and an access point.

21. The computer program product of claim 19, wherein the one or more parameters are determined by receiving, over-the-air, a system information block transmitted from the access point.

22. The computer program product of claim 13, wherein frequency domain detection is single segment frequency domain detection comprising:

performing a cyclic cross-correlation with a local replica of a random access sequence;

determining a random access channel signal at a selected antenna of a base station, wherein the base station is configured to perform the determining;

performing a segment correlation for a selected root associated with the random access sequence; and

performing cyclic cross correlation for each root sequence associated with the random access sequence.

23. The computer program product of claim 22, wherein the generating a residual signal by cancelling out the signal indicative of a strong user comprises:

determining a plurality of channel estimates for the strong user;

performing a frequency transformation on the plurality of channel estimates for the strong user to obtain a channel frequency response per antenna of the base station;

obtaining a frequency domain product, wherein the frequency domain product is a product of a channel frequency response and a result of performing the single segment frequency domain detection on the signal indicative of a strong user and a desired user, wherein the channel frequency response is based, at least, on the plurality of channel estimates for the strong user; and

generating the residual signal by subtracting the frequency domain product from the single segment frequency domain detection on the signal indicative of a strong user and a desired user.

24. The computer program product of claim 13, wherein frequency domain detection is multi-segment frequency domain detection comprising:

dividing the signal indicative of a strong user and a desired user on a physical random access channel into multiple segments;

performing frequency domain matching on zero padded versions of the multiple segments;

performing circular correlation via frequency domain multiplication;

estimating channel estimates per segment, and generating a channel frequency response per segment;

obtaining a plurality of frequency domain products, wherein the plurality of frequency domain products are products of channel frequency responses and results of performing the multi-segment frequency domain detection on multiple segments of the signal indicative of a strong user and a desired user, wherein each of the channel frequency responses are based, at least, on a plurality of channel estimates for the strong user; and

generating residual signals by subtracting the plurality of frequency domain products from respective multi-segment frequency domain detection on multiple segments of the signal indicative of a strong user and a desired user.

25. An apparatus, comprising:

means for receiving a signal indicative of a strong user and a desired user on a physical random access channel;

means for performing at least one of a single segment frequency domain detection or a multi-segment frequency domain detection on the signal indicative of a strong user and a desired user;

means for generating a residual signal by cancelling out the signal indicative of a strong user; and

means for obtaining a message transmitted by a user equipment by performing at least one of the single segment frequency domain detection or multi-segment frequency domain detection on the residual signal.

26. The apparatus of claim 25, wherein the message is a random access message received on the physical random access channel.

27. The apparatus of claim 26, wherein the physical random access channel is received on a set of resources such that the physical random access channel for a first base station interferes with a physical random access channel for a second base station.

28. The apparatus of claim 27, wherein the second base station is an access point.

29. The apparatus of claim 27, wherein the first base station is associated with at least one of a pico cell or a Femto cell, and wherein the second base station is associated with a macro cell.

30. The apparatus of claim 28, wherein a time duration of a physical random access channel for a second base station overlaps with and is a subset of a time duration of a physical random access channel for a first base station.

31. The apparatus of claim 28, further comprising means for receiving one or more parameters related to transmission of the physical random access channel to the access point, and means for selecting resources for receiving the physical random access channel at the first base station based, at least, on one or more parameters related to transmission of the physical random access channel to the access point.

32. The apparatus of claim 31, wherein one or more parameters are received over a backhaul communicatively coupled between the first base station and an access point.

33. The apparatus of claim 31, wherein one or more parameters are determined by receiving, over-the-air, a system information block transmitted from the access point.

34. The apparatus of claim 25, wherein frequency domain detection is single segment frequency domain detection, the apparatus further comprising:

means for performing a cyclic cross-correlation with a local replica of a random access sequence;

means for determining a random access channel signal at a selected antenna of a base station, wherein the base station is configured to perform the determining;

means for performing a segment correlation for a selected root associated with the random access sequence; and

means for performing cyclic cross correlation for each root sequence associated with the random access sequence.

35. The apparatus of claim 34, wherein said means for generating a residual signal by cancelling out the signal indicative of a strong user comprises:

means for determining a plurality of channel estimates for the strong user;

means for performing a frequency transformation on the plurality of channel estimates for the strong user to obtain a channel frequency response per antenna of the base station;

means for obtaining a frequency domain product, wherein the frequency domain product is a product of a channel frequency response and a result of performing the single segment frequency domain detection on the signal indicative of a strong user and a desired user, wherein the channel frequency response is based, at least, on the plurality of channel estimates for the strong user; and

means for generating the residual signal by subtracting the frequency domain product from the single segment frequency domain detection on the signal indicative of a strong user and a desired user.

36. The apparatus of claim 25, wherein frequency domain detection is multi-segment frequency domain detection, the apparatus further comprising:

means for dividing the signal indicative of a strong user and a desired user on a physical random access channel into multiple segments;

means for performing frequency domain matching on zero padded versions of the multiple segments;

means for performing circular correlation via frequency domain multiplication;

means for estimating channel estimates per segment, and generating a channel frequency response per segment;

means for obtaining a plurality of frequency domain products, wherein the plurality of frequency domain products are products of channel frequency responses and results of performing the multi-segment frequency domain detection on multiple segments of the signal indicative of a strong user and a desired user, wherein each of the channel frequency responses are based, at least, on a plurality of channel estimates for the strong user; and

means for generating residual signals by subtracting the plurality of frequency domain products from respective multi-segment frequency domain detection on multiple segments of the signal indicative of a strong user and a desired user.

37. An apparatus, comprising:

a physical random access channel processing module configured to;

receive a signal indicative of a strong user and a desired user on a physical random access channel;

perform at least one of a single segment frequency domain detection or a multi-segment frequency domain detection on the signal indicative of a strong user and a desired user;

generate a residual signal by cancelling out the signal indicative of a strong user; and

obtain a message transmitted by a user equipment by performing at least one of the single segment frequency domain detection or multi-segment frequency domain detection on the residual signal.

38. The apparatus of claim 37, wherein the message is a random access message received on the physical random access channel.

39. The apparatus of claim 38, wherein the physical random access channel is received on a set of resources such that the physical random access channel for a first base station interferes with a physical random access channel for a second base station.

40. The apparatus of claim 39, wherein the second base station is an access point.

41. The apparatus of claim 39, wherein the first base station is associated with at least one of a pico cell or a Femto cell, and wherein the second base station is associated with a macro cell.

42. The apparatus of claim 40, wherein a time duration of a physical random access channel for a second base station overlaps with and is a subset of a time duration of a physical random access channel for a first base station.

43. The apparatus of claim 40, further comprising receiving one or more parameters related to transmission of the physical random access channel to the access point, and selecting resources for receiving the physical random access channel at the first base station based, at least, on the one or more parameters related to transmission of the physical random access channel to the access point.

44. The apparatus of claim 43, wherein the one or more parameters are received over a backhaul communicatively coupled between the first base station and an access point.

45. The apparatus of claim 43, wherein the one or more parameters are determined by receiving, over-the-air, a system information block transmitted from the access point.

46. The apparatus of claim 37, wherein frequency domain detection is single segment frequency domain detection comprising:

performing a cyclic cross-correlation with a local replica of a random access sequence;

determining a random access channel signal at a selected antenna of a base station, wherein the base station is configured to perform the determining;

performing a segment correlation for a selected root associated with the random access sequence; and

performing cyclic cross correlation for each root sequence associated with the random access sequence.

47. The apparatus of claim 46, and wherein the generating a residual signal by cancelling out the signal indicative of a strong user comprises:

determining a plurality of channel estimates for the strong user;

performing a frequency transformation on the plurality of channel estimates for the strong user to obtain a channel frequency response per antenna of the base station;

obtaining a frequency domain product, wherein the frequency domain product is a product of a channel frequency response and a result of performing the single segment frequency domain detection on the signal indicative of a strong user and a desired user, wherein the channel frequency response is based, at least, on the plurality of channel estimates for the strong user; and

generating the residual signal by subtracting the frequency domain product from the single segment frequency domain detection on the signal indicative of a strong user and a desired user.

48. The apparatus of claim 37, wherein frequency domain detection is multi-segment frequency domain detection comprising:

dividing the signal indicative of a strong user and a desired user on a physical random access channel into multiple segments;

performing frequency domain matching on zero padded versions of the multiple segments;

performing circular correlation via frequency domain multiplication;

estimating channel estimates per segment, and generating a channel frequency response per segment;

obtaining a plurality of frequency domain products, wherein the plurality of frequency domain products are products of channel frequency responses and results of performing the multi-segment frequency domain detection on multiple segments of the signal indicative of a strong user and a desired user, wherein each of the channel frequency responses are based, at least, on a plurality of channel estimates for the strong user; and

generating residual signals by subtracting the plurality of frequency domain products from respective multi-segment frequency domain detection on multiple segments of the signal indicative of a strong user and a desired user.