Symbol error detection for bluetooth enhanced data rate packets

• US 8,885,776 B2
• Filed: 02/19/2013
• Issued: 11/11/2014
• Est. Priority Date: 05/13/2010
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ozgur, Soner
• Primary Examiner(s): Timory, Kabir A
• Application Number:
  US13/770,491
• Publication Number:
  US 20130163655A1
• Time in Patent Office: 630 Days
• Field of Search: 375/329, 375/331, 375/332, 375/340, 375/373, 375/376
• US Class Current: 375/329
• CPC Class Codes: H04L 1/0001 Systems modifying transmission characteristics according to link quality, e.g. power backoff adaptive data allocation for multicarrier modulation H04L5/0044; controlling transmission power for radio systems H04W52/04
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0047 Decoding adapted to other signal detection operation in conjunction with sequence estimation or equalization H04L25/03286
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/205 jitter monitoring

Abstract

A symbol error detector can be configured to detect symbol errors of a Bluetooth enhanced data rate (EDR) packet without relying solely on a CRC error detection mechanism. After a phase of a current symbol is demodulated to determine a demodulated current symbol, the phase of the demodulated current symbol can be subtracted from the phase of the current symbol prior to demodulation to yield a phase error. The phase error can be compared against a phase error threshold to determine a potential unreliability of the demodulated current symbol. The phase error being greater than the phase error threshold can indicate that the demodulated current symbol may be unreliable. Accordingly, a symbol error notification can be generated to indicate that the demodulated current symbol may be unreliable.

Claims

1. A method comprising:

determining, at a wireless network device, a phase of a first symbol of a received signal;

determining that the phase of the first symbol is within a symbol phase boundary of a predefined symbol;

determining a phase error that indicates a difference between the phase of the first symbol and a phase of the predefined symbol;

comparing the phase error to a phase error threshold; and

determining whether to generate a symbol error notification based on said comparing the phase error to the phase error threshold.

2. The method of claim 1, wherein said determining the phase error comprises:

determining an absolute value of the difference between the phase of the first symbol and the phase of the predefined symbol, or

determining a squared magnitude of the difference between the phase of the first symbol and the phase of the predefined symbol.

3. The method of claim 1, further comprising:

determining that the phase error is greater than the phase error threshold;

determining a number of symbols between a current symbol error and a previously detected symbol error, wherein the current symbol error is associated with the first symbol of the received signal;

comparing the number of symbols between the current symbol error and the previously detected symbol error to a burst length threshold, wherein the burst length threshold indicates a minimum number of symbols between two consecutive symbol errors that will cause an erroneously demodulated symbol to be undetected; and

generating the symbol error notification in response to determining that

the phase error is greater than the phase error threshold, and

the number of symbols between the current symbol error and the previously detected symbol error is greater than the burst length threshold.

4. The method of claim 3, further comprising discarding the first symbol based, at least in part, on determining that

the phase error is greater than the phase error threshold and the number of symbols, and

the previously detected symbol error is greater than the burst length threshold.

5. The method of claim 1, wherein said determining that the phase of the first symbol is within the symbol phase boundary of the predefined symbol comprises:

comparing the phase of the first symbol with symbol phase boundaries associated with a plurality of phases of a plurality of predefined symbols.

6. The method of claim 5, further comprising:

mapping the first symbol to a first of the plurality of predefined symbols associated with a first of the plurality of phases, wherein

said mapping the first symbol is based on determining that the phase of the first symbol lies within symbol phase boundaries associated with the first of the plurality of phases.

7. The method of claim 1, further comprising, for a second symbol of the received signal:

determining, at the wireless network device, a phase of the second symbol;

determining that the phase of the second symbol is within the symbol phase boundary of the predefined symbol;

determining a second phase error that indicates a difference between the phase of the second symbol and the phase of the predefined symbol;

determining whether the second phase error is greater than the phase error threshold; and

generating a second symbol error notification in response to determining that the second phase error is greater than the phase error threshold.

8. The method of claim 1, further comprising applying a phase correction to the phase of the first symbol, wherein

the phase correction is determined, at least in part, on a frequency offset and a phase offset associated with a packet that comprises the first symbol.

9. The method of claim 8, further comprising recalculating the phase correction based, at least in part, on the phase error.

10. The method of claim 1, further comprising discarding the first symbol and a packet that comprises the first symbol based, at least in part, on determining that the phase error is greater than the phase error threshold.

11. The method of claim 1, wherein the received signal is modulated using,

π

/4 rotated differential encoded quadrature phase shift keying (π

/4 DQPSK), or

8-phase differential encoded phase shift keying (8-DPSK).

12. The method of claim 1, further comprising:

demodulating the first symbol to the predefined symbol based on said determining that the phase of the first symbol is within the symbol phase boundary of the predefined symbol.

13. The method of claim 12, wherein said demodulating the first symbol to the predefined symbol comprises:

determining that the phase of the first symbol lies within symbol phase boundaries associated with the phase of the predefined symbol; and

mapping the first symbol to the predefined symbol in response to said determining that the phase of the first symbol lies within the symbol phase boundaries associated with the phase of the predefined symbol.

14. The method of claim 1, further comprising generating the symbol error notification in response to determining that the phase error is greater than the phase error threshold.

15. The method of claim 1, wherein the wireless network device is configured to implement at least one member in a group consisting of,

a Bluetooth communication protocol, and

a wireless local area network (WLAN) communication protocol.

16. A wireless network device comprising:

a processor;

a receiver unit coupled with the processor, the receiver unit operable to;

determine a phase of a first symbol of a received signal;

determine that the phase of the first symbol is within a symbol phase boundary of a predefined symbol;

determine a phase error that indicates a difference between the phase of the first symbol and a phase of the predefined symbol;

compare the phase error with a phase error threshold; and

determine whether to generate a symbol error notification based on comparing the phase error with the phase error threshold.

17. The wireless network device of claim 16, wherein the receiver unit operable to determine the phase error further comprises the receiver unit operable to:

determine an absolute value of the difference between the phase of the first symbol and the phase of the predefined symbol, or

determine a squared magnitude of the difference between the phase of the first symbol and the phase of the predefined symbol.

18. The wireless network device of claim 16, wherein the receiver unit is further operable to:

determine that the phase error is greater than the phase error threshold;

determine a number of symbols between a current symbol error and a previously detected symbol error, wherein the current symbol error is associated with the first symbol of the received signal;

compare the number of symbols between the current symbol error and the previously detected symbol error to a burst length threshold, wherein the burst length threshold indicates a minimum number of symbols between two consecutive symbol errors that will cause an erroneously demodulated symbol to be undetected; and

generate the symbol error notification in response to the receiver unit determining that

the phase error is greater than the phase error threshold, and

the number of symbols between the current symbol error and the previously detected symbol error is greater than the burst length threshold.

19. The wireless network device of claim 18, wherein the receiver unit is further operable to discard the first symbol based, at least in part, on

determining that the phase error is greater than the phase error threshold and the number of symbols, and

the previously detected symbol error is greater than the burst length threshold.

20. The wireless network device of claim 16, wherein the receiver unit is further operable to discard the first symbol and a packet that comprises the first symbol in response to determining that the phase error is greater than the phase error threshold.

21. The wireless network device of claim 16, wherein the receiver unit is operable to:

compare the phase of the first symbol with symbol phase boundaries associated with a plurality of phases of a plurality of predefined symbols; and

map the first symbol to a first of the plurality of predefined symbols associated with a first of the plurality of phases of the plurality of predefined symbols, wherein

the receiver unit is operable to map the first symbol based on determining that the phase of the first symbol lies within symbol phase boundaries associated with the first of the plurality of phases.

22. The wireless network device of claim 16, wherein the receiver unit is further operable to apply a phase correction to the phase of the first symbol, wherein the phase correction is determined, at least in part, on the phase error.

23. The wireless network device of claim 22, wherein the receiver unit is further operable to recalculate the phase correction based, at least in part, on the phase error.

24. The wireless network device of claim 16, wherein the received signal is modulated using,

π

/4 rotated differential encoded quadrature phase shift keying (π

/4 DQPSK), or

8-phase differential encoded phase shift keying (8-DPSK).

25. The wireless network device of claim 16, wherein the receiver unit is further operable to:

demodulate the first symbol to the predefined symbol based on determining that the phase of the first symbol is within the symbol phase boundary of the predefined symbol.

26. The wireless network device of claim 25, wherein the receiver unit operable to demodulate the first symbol comprises the receiver unit operable to:

determine that the phase of the first symbol lies within symbol phase boundaries associated with the phase of the predefined symbol; and

map the first symbol to the predefined symbol in response to determining that the phase of the first symbol lies within the symbol phase boundaries associated with the phase of the predefined symbol.

27. The wireless network device of claim 16, wherein the receiver unit is further operable to generate the symbol error notification in response to determining that the phase error is greater than the phase error threshold.

28. The wireless network device of claim 16, wherein the wireless network device is configured to implement at least one member in a group consisting of,

a Bluetooth communication protocol, and

a wireless local area network (WLAN) communication protocol.

29. A non-transitory machine-readable storage medium, having instructions stored therein, which, when executed by a processor causes the processor to perform operations that comprise:

determining a phase of a first symbol of a received signal;

determining that the phase of the first symbol is within a symbol phase boundary of a predefined symbol;

determining a phase error that indicates a difference between the phase of the first symbol and a phase of the predefined symbol;

comparing the phase error to a phase error threshold; and

determining whether to generate a symbol error notification based on comparing the phase error to the phase error threshold.

30. The non-transitory machine-readable storage medium of claim 29, wherein said operation of determining the phase error comprises:

determining an absolute value of the difference between the phase of the first symbol and the phase of the predefined symbol, or

determining a squared magnitude of the difference between the phase of the first symbol and the phase of the predefined symbol.

31. The non-transitory machine-readable storage medium of claim 29, wherein the operations further comprise:

determining that the phase error is greater than the phase error threshold;

determining a number of symbols between a current symbol error and a previously detected symbol error, wherein the current symbol error is associated with the first symbol of the received signal;

comparing the number of symbols between the current symbol error and the previously detected symbol error to a burst length threshold, wherein the burst length threshold indicates a minimum number of symbols between two consecutive symbol errors that will cause an erroneously demodulated symbol to be undetected; and

generating the symbol error notification in response to determining that

the phase error is greater than the phase error threshold, and

the number of symbols between the current symbol error and the previously detected symbol error is greater than the burst length threshold.

32. The non-transitory machine-readable storage medium of claim 31, wherein the operations further comprise:

discarding the first symbol based, at least in part, on determining that

the phase error is greater than the phase error threshold and the number of symbols, and

the previously detected symbol error is greater than the burst length threshold.

33. The non-transitory machine-readable storage medium of claim 29, wherein the operations comprise:

comparing the phase of the first symbol with symbol phase boundaries associated with a plurality of phases of a plurality of predefined symbols; and

mapping the first symbol to a first of the plurality of predefined symbols associated with a first of the plurality of phases, wherein

said mapping the first symbol is based on determining that the phase of the first symbol lies within symbol phase boundaries associated with the first of the plurality of phases.

34. The non-transitory machine-readable storage medium of claim 29, wherein the operations further comprise discarding the first symbol and a packet that comprises the first symbol in response to determining that the phase error is greater than the phase error threshold.

35. The non-transitory machine-readable storage medium of claim 29, wherein the operations further comprise applying a phase correction to the phase of the first symbol, wherein

the phase correction is determined, at least in part, on the phase error.

36. The non-transitory machine-readable storage medium of claim 35, wherein the operations further comprise recalculating the phase correction based, at least in part, on the phase error.

37. The non-transitory machine-readable storage medium of claim 29, wherein the operations further comprise:

demodulating the first symbol to the phase of the first symbol is within the symbol phase boundary of the predefined symbol.

38. The non-transitory machine-readable storage medium of claim 37, wherein said operation of demodulating the first symbol to the predefined symbol comprises:

determining that the phase of the first symbol lies within symbol phase boundaries associated with the phase of the predefined symbol; and

mapping the first symbol to the predefined symbol in response to said determining that the phase of the first symbol lies within the symbol phase boundaries associated with the phase of the predefined symbol.

39. The non-transitory machine-readable storage medium of claim 29, wherein the operations further comprise generating the symbol error notification in response to determining that the phase error is greater than the phase error threshold.