Systems, apparatus and methods for broadcast channel decoding

1. A method of wireless communication, comprising:

decoding a broadcast channel of a current radio frame to obtain system information associated with a wireless network;

comparing a physical control format indicator channel (PCFICH) value of the current frame with an expected physical hybrid automatic repeat request indicator channel (PHICH) duration, the comparing being initiated when a cyclic redundancy check associated with the current radio frame has passed; and

rejecting the system information of the current radio frame when the PCFICH value is one or two and the PHICH duration is greater than or less than one orthogonal frequency division multiplexed (OFDM) symbol.

2. The method of claim 1 , wherein decoding the broadcast channel comprises testing a plurality of hypotheses.

3. The method of claim 2 , wherein the system information of each frame comprises a bandwidth (BW) indicator, and

further comprising rejecting the system information of the current radio frame when the BW indicator of the current radio frame does not match a BW indicator of the previous radio frame.

4. The method of claim 2 , further comprising rejecting the system information from the current radio frame based at least in part on a system frame number (SFN) associated with the previous frame.

5. The method of claim 2 , wherein the system information of each frame comprises a redundancy version (RV), and the method further comprises:

comparing a first RV associated with the current radio frame with an expected RV determined from the system information from the previous radio frame; and

rejecting the system information of the current radio frame when the first RV does not match the expected RV.

6. A non-transitory computer-readable medium having program code recorded thereon, the program code comprising:

program code to decode a broadcast channel of a current radio frame to obtain system information associated with a wireless network;

program code to compare a physical control format indicator channel (PCFICH) value of the current frame with an expected physical hybrid automatic repeat request indicator channel (PHICH) duration, the comparing being initiated when a cyclic redundancy check associated with the current radio frame has passed; and

program code to reject the system information of the current radio frame when the PCFICH value is one or two and the PHICH duration is greater than or less than one orthogonal frequency division multiplexed OFDM symbol.

7. The non-transitory computer-readable medium of claim 6 , wherein the program code to decode the broadcast channel comprises program code to test a plurality of hypotheses.

8. The non-transitory computer-readable medium of claim 7 , wherein the system information of each frame comprises a bandwidth (BW) indicator, and the program code to reject comprises program code to reject the system information of the current radio frame when the BW indicator of the current radio frame does not match a BW indicator of the previous radio frame.

9. The non-transitory computer-readable medium of claim 7 , wherein the program code to reject comprises program code to reject the system information from the current radio frame based at least in part on a system frame number (SFN) associated with the previous frame.

10. The non-transitory computer-readable medium of claim 7 , wherein:

the system information of each frame comprises a redundancy version (RV);

the program code to compare comprises program code to compare a first RV associated with the current radio frame with an expected RV determined from the previous radio frame; and

the program code to reject comprises program code to reject the system information of the current radio frame when it is determined that the first RV does not match the expected RV.

11. An apparatus, comprising:

means for decoding a broadcast channel of a current radio frame to obtain system information associated with a wireless network;

means for comparing a physical control format indicator channel (PCFICH) value of the current frame with an expected physical hybrid automatic repeat request indicator channel (PHICH), the comparing being initiated when a cyclic redundancy check associated with the current radio frame has passed; and

means for rejecting the system information of the current radio frame when the PCFICH value is one or two and the PHICH duration is greater than or less than one orthogonal frequency division multiplexed OFDM symbol.

12. The apparatus of claim 11 , wherein the means for decoding the broadcast channel comprises means for testing a plurality of hypotheses.

13. The apparatus of claim 11 , wherein the system information of each frame comprises a bandwidth (BW) indicator, and apparatus further comprises means for rejecting the system information of the current radio frame when the BW indicator of the current radio frame does not match a BW indicator of the previous radio frame.

14. The apparatus of claim 11 , further comprising means for rejecting the system information from the current radio frame based at least in part on a system frame number (SFN) associated with the previous frame.

15. The apparatus of claim 11 , wherein the system information of each frame comprises a redundancy version (RV), and the apparatus further comprises:

means for comparing a first RV associated with the current radio frame with an expected RV determined from the previous radio frame; and

means for rejecting the system information of the current radio frame when the first RV does not match the expected RV.

16. An apparatus, comprising:

a memory unit; and

at least one processor coupled to the memory, the at least one processor configured to:

decode a broadcast channel of a current radio frame to obtain system information associated with a wireless network; and

compare a physical control format indicator channel (PCFICH) value of the current frame with an expected physical hybrid automatic repeat request indicator channel (PHICH) duration, the comparing being initiated when a cyclic redundancy check associated with the current radio frame has passed; and

reject the system information of the current radio frame when the PCFICH value is one or two and the PHICH duration is greater than or less than one orthogonal frequency division multiplexed OFDM symbol.

17. The apparatus of claim 16 , wherein the at least one processor is further configured to test a plurality of hypotheses.

18. The apparatus of claim 17 , wherein:

the system information of each frame comprises a bandwidth (BW) indicator, and

the at least one processor is further configured to reject the system information of the current radio frame when the BW indicator of the current radio frame does not match a BW indicator of the previous radio frame.

19. The apparatus of claim 17 , wherein the at least one processor is further configured to reject the system information from the current radio frame based at least in part on a system frame number (SFN) associated with the previous frame.

20. The apparatus of claim 17 , wherein:

the system information of each frame comprises a redundancy version (RV), and

the at least one processor is further configured:

to compare a first RV associated with the current radio frame with an expected RV determined from the previous radio frame; and

to reject the system information of the current radio frame when the first RV does not match the expected RV.

21. A method for decoding a broadcast channel in a wireless communication system, the method comprising:

receiving a downlink transmission comprising a physical broadcast channel (PBCH);

decoding the PBCH:

to obtain a first decoded PBCH payload, the decoding being performed over a plurality of radio frames,

to determine whether a cyclic redundancy check (CRC) for the first decoded PBCH payload is acceptable, the determining for the CRC being performed during a decoding of a first radio frame of the plurality of radio frames, and

to determine whether a redundancy value (RV) index associated with the first decoded PBCH payload is less than a selected value;

detecting an error condition related to the first decoded PBCH payload based at least in part on a second decoded PBCH payload obtained prior to the first decoded PBCH payload; and

rejecting the first decoded PBCH payload in response to detecting the error condition.

22. The method of claim 21 , wherein:

the PBCH is decoded until a successful cyclic redundancy check is achieved for the first decoded PBCH payload, and

decoding the PBCH comprises testing a plurality of hypotheses.

23. The method of claim 22 , wherein detecting the error condition comprises one or more of:

determining that a bandwidth (BW) field associated with the first decoded PBCH payload does not match a BW field associated with the second decoded PBCH payload,

determining that the BW field associated with the first decoded payload and a reserved bit associated with the first decoded PBCH payload do not match a BW field associated with the second decoded PBCH payload and a reserved bit associated with the second decoded PBCH payload, respectively, or

a combination thereof.

24. The method of claim 22 , wherein detecting the error condition comprises one or more of:

determining that a system frame number associated with the first decoded PBCH payload is indicative of an incorrect number of PBCH frames between a frame associated with the first decoded PBCH payload and a frame associated with the second decoded PBCH payload,

determining that a redundancy value (RV) index is inconsistent with an expectation for a known frame boundary for the PBCH,

determining that a physical control format indicator channel (PCFICH) value is inconsistent with an expected Physical HARQ Indicator Channel (PHICH) duration, or

a combination thereof.

25. The method of claim 24 , wherein the PCFICH value is determined to be inconsistent with the expected PHICH duration when the PCFICH value is one or two and the PHICH duration is greater than or less than one OFDM symbol.

26. The method of claim 21 , further comprising:

storing the first decoded PBCH payload when the CRC for the first decoded PBCH payload is determined to be acceptable; and

wherein detecting the error condition comprises determining whether a CRC for the first decoded PBCH payload is acceptable during a decoding of a second frame of the plurality of radio frames, wherein the second frame of the plurality of radio frames is later in time than a first frame of the plurality of radio frames.

27. The method of claim 26 , further comprising accepting the first decoded PBCH payload in response to:

determining that the CRC for the first decoded PBCH payload is acceptable during the decoding for the second frame of the plurality of radio frames;

determining that an RV index associated with the first decoded PBCH payload is a specific value when the first frame of the plurality of radio frames is immediately prior to the second frame of the plurality of radio frames; and

determining that the first decoded PBCH payload matches the second decoded PBCH payload.

28. The method of claim 26 , further comprising discarding the second decoded PBCH payload and storing the first decoded PBCH payload in response to:

determining that the CRC for the first decoded PBCH payload is acceptable during the decoding for the second frame of the plurality of radio frames;

determining that an RV index associated with the first decoded PBCH payload is not a specific value when the first frame of the plurality of radio frames is immediately prior to the second frame of the plurality of radio frames; and

determining that the first decoded PBCH payload does not match the second decoded PBCH payload.

29. The method of claim 26 , further comprising discarding the first decoded PBCH payload in response to determining that the CRC for the first decoded PBCH payload is not acceptable.

30. The method of claim 21 ,

further comprising determining whether the error condition is related to the first decoded PBCH payload, by:

comparing a plurality of cyclic redundancy checks (CRCs) on preambles of a plurality of decoded payloads, wherein the first decoded PBCH payload is one of the plurality of decoded payloads;

selecting at least one decoded payload associated with a largest number of CRC passes when a plurality of decoded payloads are associated with acceptable CRCs; and

selecting one of the at least one decoded payload associated with a largest redundancy value index when a plurality of the decoded payloads are associated with the largest number of CRC passes.

31. A non-transitory computer-readable medium having program code recorded thereon, the program code comprising:

program code to receive a downlink transmission comprising a physical broadcast channel (PBCH);

program code:

to decode the PBCH to obtain a first decoded PBCH payload, the decoding being performed over a plurality of radio frames,

to determine whether a cyclic redundancy check (CRC) for the first decoded PBCH payload is acceptable, the determining for the CRC being performed during a decoding of a first radio frame of the plurality of radio frames, and

to determine whether a redundancy value (RV) index associated with the first decoded PBCH payload is less than a selected value;

program code to detect an error condition related to the first decoded PBCH payload based at least in part on a second decoded PBCH payload obtained prior to the first decoded PBCH payload; and

program code to reject the first decoded PBCH payload in response to detecting the error condition.

32. The non-transitory computer-readable medium of claim 31 , wherein:

the program code to decode the PBCH is performed until a successful cyclic redundancy check is achieved for the first decoded PBCH payload, and

the program code to decode comprises program code to test a plurality of hypotheses.

33. The non-transitory computer-readable medium of claim 32 , wherein the program code to detect the error condition comprises one or more of:

program code to determine that a bandwidth (BW) field associated with the first decoded PBCH payload does not match a BW field associated with the second decoded PBCH payload,

program code to determine that the BW field associated with the first decoded payload and a reserved bit associated with the first decoded PBCH payload do not match a BW field associated with the second decoded PBCH payload and a reserved bit associated with the second decoded PBCH payload, respectively, or

a combination thereof.

34. The non-transitory computer-readable medium of claim 32 , wherein the program code to detect the error condition comprises one or more of:

program code to determine a system frame number (SFN) associated with the first decoded PBCH payload is indicative of an incorrect number of PBCH frames between a frame associated with the first decoded PBCH payload and a frame associated with the second decoded PBCH payload,

program code to determine a redundancy value (RV) index is included with an expectation for a known frame boundary for the PBCH,

program code to determine a physical control format indicator channel (PCFICH) value is inconsistent with an expected Physical HARQ Indicator Channel (PHICH) duration, or

a combination thereof.

35. The non-transitory computer-readable medium of claim 34 , wherein the PCFICH value is determined to be inconsistent with the expected PHICH duration when the PCFICH value is one or two and the PHICH duration is greater than or less than one OFDM symbol.

36. The non-transitory computer-readable medium of claim 31 , in which the program code further comprises:

program code to store the first decoded PBCH payload when the CRC for the first decoded PBCH payload is determined to be acceptable; and

in which the program code to detect the error condition comprises program code to determine whether a CRC for the first decoded PBCH payload is acceptable during a decoding of a second frame of the plurality of radio frames, wherein the second frame of the plurality of radio frames is later in time than a first frame of the plurality of radio frames.

37. The non-transitory computer-readable medium of claim 36 , further comprising program code to accept the first decoded PBCH payload in response to:

determining that the CRC for the first decoded PBCH payload is acceptable when the program code to decode is decoding the second frame of the plurality of radio frames;

determining that an RV index associated with the first decoded PBCH payload is a specific value when the first frame of the plurality of radio frames is immediately prior to the second frame of the plurality of radio frames; and

determining that the first decoded PBCH payload matches the second decoded PBCH payload.

38. The non-transitory computer-readable medium of claim 36 , further comprising program code to discard the second decoded PBCH payload and to store the first decoded PBCH payload in response to:

determining that the CRC for the first decoded PBCH payload is acceptable when the program code to decode is decoding the second frame of the plurality of radio frames;

determining that an RV index associated with the first decoded PBCH payload is not a specific value when the first frame of the plurality of radio frames is immediately prior to the second frame of the plurality of radio frames; and

determining that the first decoded PBCH payload does not match the second decoded PBCH payload.

39. The non-transitory computer-readable medium of claim 36 , further comprising program code to discard the first decoded PBCH payload in response to determining that the CRC for the first decoded PBCH payload is not acceptable.

40. The non-transitory computer-readable medium of claim 31 ,

further comprising program code to determine whether the error condition is related to the first decoded PBCH payload, the program code to determine comprising:

program code to compare a plurality of CRCs on preambles of a plurality of decoded payloads, wherein the first decoded PBCH payload is one of the plurality of decoded payloads;

program code to select at least one decoded payload associated with a largest number of cyclic redundancy check passes when a plurality of decoded payloads are associated with acceptable CRCs; and

program code to select one of the at least one decoded payload associated with a largest redundancy value index when a plurality of the decoded payloads are associated with the largest number of CRC passes.

41. An apparatus, comprising:

means for receiving a downlink transmission comprising a physical broadcast channel (PBCH);

means for decoding the PBCH:

to obtain a first decoded PBCH payload, the PBCH being decoded over a plurality of radio frames,

to determine whether a cyclic redundancy check (CRC) for the first decoded PBCH payload is acceptable, the determining for the CRC being performed during a decoding of a first radio frame of the plurality of radio frames, and

to determine whether a redundancy value (RV) index associated with the first decoded PBCH payload is less than a selected value;

means for detecting an error condition related to the first decoded PBCH payload based at least in part on a second decoded PBCH payload obtained prior to the first decoded PBCH payload; and

means for rejecting the first decoded PBCH payload in response to detecting the error condition.

42. The apparatus of claim 41 , wherein:

the PBCH is decoded until a successful cyclic redundancy check (CRC) is achieved for the first decoded PBCH payload, and

the means for decoding further comprises means for testing a plurality of hypotheses.

43. The apparatus of claim 42 , wherein the means for detecting the error condition comprises one or more of:

determining that a bandwidth (BW) field associated with the first decoded PBCH payload does not match a BW field associated with the second decoded PBCH payload,

determining that the BW field associated with the first decoded payload and a reserved bit associated with the first decoded PBCH payload do not match a BW field associated with the second decoded PBCH payload and a reserved bit associated with the second decoded PBCH payload, respectively, or

a combination thereof.

44. The apparatus of claim 42 , wherein the means for detecting the error condition comprises one or more of:

determining that a system frame number associated with the first decoded PBCH payload is indicative of an incorrect number of PBCH frames between a frame associated with the first decoded PBCH payload and a frame associated with the second decoded PBCH payload,

determining that a redundancy value (RV) index is included with an expectation for a known frame boundary for the PBCH,

determining that a physical control format indicator channel (PCFICH) value is inconsistent with an expected Physical Hybrid ARQ Indicator Channel (PHICH) duration, or

a combination thereof.

45. The apparatus of claim 44 , wherein the PCFICH value is inconsistent with the expected PHICH duration when the PCFICH value is one or two and the PHICH duration is greater than or less than one OFDM symbol.

46. The apparatus of claim 41 , further comprising:

means for storing the first decoded PBCH payload when the CRC for the first decoded PBCH payload is determined to be acceptable; and

wherein the means for detecting the error condition comprises means for determining whether a CRC for the first decoded PBCH payload is acceptable during a decoding of a second frame of the plurality of radio frames, wherein the second frame of the plurality of radio frames is later in time than a first frame of the plurality of radio frames.

47. The apparatus of claim 46 , further comprising means for accepting the first decoded PBCH payload in response to:

determining that the CRC for the first decoded PBCH payload is acceptable during the decoding for the second frame of the plurality of radio frames;

determining that a RV index associated with the first decoded PBCH payload is a specific value when the first frame of the plurality of radio frames is immediately prior to the second frame of the plurality of radio frames; and

determining that the first decoded PBCH payload matches the second decoded PBCH payload.

48. The apparatus of claim 46 , further comprising means for

discarding the second decoded PBCH payload and storing the first decoded PBCH payload in response to:

determining that the CRC for the first decoded PBCH payload is acceptable during the decoding for the second frame of the plurality of radio frames:

determining that an RV index associated with the first decoded PBCH payload is not a specific value when the first frame of the plurality of radio frames is immediately prior to the second frame of the plurality of radio frames; and

determining that the first decoded PBCH payload does not match the second decoded PBCH payload.

49. The apparatus of claim 46 , further comprising means for

discarding the first decoded PBCH payload in response to determining that the CRC for the first decoded PBCH payload is not acceptable.

50. The apparatus of claim 41 ,

further comprising means for determining whether the error condition is related to the first decoded PBCH payload, the means for determining comprising:

means for comparing a plurality of CRCs on preambles of a plurality of decoded payloads, wherein the first decoded PBCH payload is one of the plurality of decoded payloads;

means for selecting at least one decoded payload associated with a largest number of CRC passes when a plurality of decoded payloads are associated with acceptable CRCs; and

means for selecting one of the at least one decoded payload associated with a largest redundancy value index when a plurality of the decoded payloads are associated with the largest number of CRC passes.

51. An apparatus, comprising:

a memory unit;

a transceiver configured to receive a downlink transmission comprising a physical broadcast channel (PBCH); and

at least one processor coupled to the memory unit, the at least one processor configured to:

decode the PBCH:

to obtain a first decoded PBCH payload, the PBCH being decoded over a plurality of radio frames,

to determine whether a cyclic redundancy check (CRC) for the first decoded PBCH payload is acceptable, the determining for the CRC being performed during a decoding of a first radio frame of the plurality of radio frames, and

to determine whether a redundancy value (RV) index associated with the first decoded PBCH payload is less than a selected value;

detect an error condition related to the first decoded PBCH payload based at least in part on a second decoded PBCH payload obtained prior to the first decoded PBCH payload; and

reject the first decoded PBCH payload in response to detecting the error condition.

52. The apparatus of claim 51 , wherein the at least one processor is further configured to:

decode the PBCH until a successful cyclic redundancy check (CRC) is achieved for the first decoded PBCH payload, and

test a plurality of hypotheses.

53. The apparatus of claim 52 , wherein the at least one processor is further configured to detect the error condition based at least in part on one or more of:

determining that a bandwidth (BW) field associated with the first decoded PBCH payload does not match a BW field associated with the second decoded PBCH payload,

determining that the BW field associated with the first decoded payload and a reserved bit associated with the first decoded PBCH payload do not match a BW field associated with the second decoded PBCH payload and a reserved bit associated with the second decoded PBCH payload, respectively, or

a combination thereof.

54. The apparatus of claim 52 , wherein the at least one processor is further configured to detect the error condition based at least in part on one or more of:

determining that a system frame number (SFN) associated with the first decoded PBCH payload is indicative of an incorrect number of PBCH frames between a frame associated with the first decoded PBCH payload and a frame associated with the second decoded PBCH payload,

determining that a redundancy value (RV) index is included with an expectation for a known frame boundary for the PBCH,

determining that a physical control format indicator channel (PCFICH) value is inconsistent with an expected Physical Hybrid ARQ Indicator Channel (PHICH) duration, or

a combination thereof.

55. The apparatus of claim 54 , wherein the PCFICH value is inconsistent with the expected PHICH duration when the PCFICH value is one or two and the PHICH duration is greater than or less than one OFDM symbol.

56. The apparatus of claim 51 ,

wherein the at least one processor is further configured to:

store the first decoded PBCH payload when the CRC for the first decoded PBCH payload is determined to be acceptable; and

detect the error condition based at least in part on determining whether a CRC for the first decoded PBCH payload is acceptable during a decoding of a second frame of the plurality of radio frames, wherein the second frame of the plurality of radio frames is later in time than a first frame of the plurality of radio frames.

57. The apparatus of claim 56 , wherein the at least one processor is further configured to accept the first decoded PBCH payload in response to:

determining that the CRC for the first decoded PBCH payload is acceptable during the decoding for the second frame of the plurality of radio frames;

determining that an RV index associated with the first decoded PBCH payload is a specific value when the first frame of the plurality of radio frames is immediately prior to the second frame of the plurality of radio frames; and

determining that the first decoded PBCH payload matches the second decoded PBCH payload.

58. The apparatus of claim 56 , wherein the at least one processor is further configured to discard the second decoded PBCH payload and store the first decoded PBCH payload in response to:

determining that the CRC for the first decoded PBCH payload is acceptable during the decoding for the second frame of the plurality of radio frames,

determining that an RV index associated with the first decoded PBCH payload is not a specific value when the first frame of the plurality of radio frames is immediately prior to the second frame of the plurality of radio frames; and

determining that the first decoded PBCH payload does not match the second decoded PBCH payload.

59. The apparatus of claim 56 , wherein the at least one processor is further configured to discard the first decoded PBCH payload in response to determining that the CRC for the first decoded PBCH payload is not acceptable.

60. The apparatus of claim 51 , wherein the at least one processor is further configured to:

determine whether the error condition is related to the first decoded PBCH payload, and

determine whether the error condition is related to the first decoded PBCH payload based at least in part on:

comparing a plurality of CRCs on preambles of a plurality of decoded payloads, wherein the first decoded PBCH payload is one of the plurality of decoded payloads;

selecting at least one decoded payload associated with a largest number of CRC passes when a plurality of decoded payloads are associated with acceptable CRCs; and

selecting one of the at least one decoded payload associated with a largest redundancy value index when a plurality of the decoded payloads are associated with the largest number of CRC passes.