METHOD AND SYSTEM FOR SAVING POWER FOR PACKET RE-TRANSMISSION IN AN ENCRYPTED BLUETOOTH LOW POWER LINK LAYER CONNECTION

• US 20110022916A1
• Filed: 08/24/2009
• Published: 01/27/2011
• Est. Priority Date: 07/24/2009
• Status: Abandoned Application

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Desai, Prasanna, Ibrahim, Brima
• Application Number:
  US12/546,628
• Publication Number:
  US 20110022916A1
• Time in Patent Office: Days
• US Class Current: 714/748
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: H04L 1/0036 arrangements specific to the receiver
• CPC Class Codes: H04L 1/0061 Error detection codes
• CPC Class Codes: H04L 1/1829 Arrangements specially adapted for the receiver end
• CPC Class Codes: H04L 2209/12 Details relating to cryptographic hardware or logic circuitry
• CPC Class Codes: H04L 2209/805 Lightweight hardware, e.g. radio-frequency identification [RFID] or sensor
• CPC Class Codes: H04L 9/0662 with particular pseudorandom sequence generator
• CPC Class Codes: H04L 9/0822 using key encryption key
• CPC Class Codes: H04L 9/3239 involving non-keyed hash functions, e.g. modification detection codes [MDCs], MD5, SHA or RIPEMD

Abstract

A Bluetooth low power (BLE) receiver receives a data packet in an encrypted link layer connection from a BLE transmitter. The data packet comprises a transmitted protocol data unit (PDU) and associated cyclic redundancy code (CRC). The PDU comprises a message integrity code (MIC). The BLE receiver determines a connection SNR. In a high connection SNR condition, the BLE receiver determines packet retransmission based on MIC verification without CRC checking. A MIC indication is generated by comparing a local MIC and the MIC in the received data packet. CRC checking is turned on or off for power saving based on the MIC indication and connection SNR. In a high connection SNR, the BLE receiver determines, without CRC checking, to retransmit the received data packet for a MIC failure indication. The local MIC is calculated using a shared secret Encryption Key of 32-bit, 64-bit or 128-bit derived from multiple entropy pools.

Claims

1. A method of processing signals, the method comprising:

performing by one or more processors and/or circuits in a Bluetooth low power (BLE) receiver;

receiving a data packet in an encrypted link layer connection from a Bluetooth low power (BLE) transmitter, wherein said data packet comprises a transmitted protocol data unit (PDU) and associated cyclic redundancy code (CRC), and said PDU comprises a message integrity code (MIC);

determining a signal to noise ration (SNR ) of said encrypted link layer connection; and

determining whether said data packet is to be retransmitted based on said MIC and said determined signal to noise ratio, wherein a CRC of said received data packet is not checked when said signal-to-noise ratio (SNR) is greater than a specified threshold.

2. The method according to claim 1, comprising calculating a local MIC for said transmitted PDU using a secret Encryption Key that is shared with said BLE transmitter.

3. The method according to claim 2, comprising comparing said calculated local MIC with said MIC in said received data packet.

4. The method according to claim 3, comprising generating a MIC indication based on said comparison.

5. The method according to claim 4, comprising turning ON or OFF CRC checking to achieve power saving based on said generated MIC indication and/or said determined signal-to-noise ratio (SNR).

6. The method according to claim 5, comprising determining whether to retransmit said data packet without said CRC checking when said generated MIC indication indicates that said calculated local MIC is different from said MIC in said received data packet.

7. The method according to claim 2, wherein said secret Encryption Key is derived from a generated random number sequence.

8. The method according to claim 7, comprising generating said random number sequence by a random number generator fed with seed entropy from multiple entropy pools comprising an analog-to-digital convertor (ADC) entropy pool and a low power oscillator (LPO) entropy pool.

9. The method according to claim 8, wherein said ADC entropy pool and said LPO entropy pool are formed from occasional and/or unlikely events on an analog-to-digital convertor (ADC) and on a low power oscillator (LPO).

10. The method according to claim 8, wherein said random number sequence comprises a 32-bit, 64-bit, or 128-bit random number sequence for said secret Encryption Key.

11. A system for processing signals, the system comprising:

one or more processors and/or circuits for use a Bluetooth low power (BLE) receiver, wherein said one or more processors and/or circuits are operable to;

receive a data packet in an encrypted link layer connection from a Bluetooth low power (BLE) transmitter, wherein said data packet comprises a transmitted protocol data unit (PDU) and associated cyclic redundancy code (CRC), and said PDU comprises a message integrity code (MIC);

determine a signal to noise ration (SNR ) of said encrypted link layer connection; and

determine whether said data packet is to be retransmitted based on said MIC and said determined signal to noise ratio, wherein a CRC of said received data packet is not checked when said signal-to-noise ratio (SNR) is greater than a specified threshold.

12. The system according to claim 11, wherein said one or more processors and/or circuits are operable to calculate a local MIC for said transmitted PDU using a secret Encryption Key that is shared with said BLE transmitter.

13. The system according to claim 12, wherein said one or more processors and/or circuits are operable to compare said calculated local MIC with said MIC in said received data packet.

14. The system according to claim 13, wherein said one or more processors and/or circuits are operable to generate a MIC indication based on said comparison.

15. The system according to claim 14, wherein said one or more processors and/or circuits are operable to turn ON or OFF CRC checking to achieve power saving based on said generated MIC indication and/or said determined signal-to-noise ratio (SNR) associated with said encrypted link layer connection.

16. The system according to claim 15, wherein said one or more processors and/or circuits are operable to determine whether to retransmit said data packet without said CRC checking when said generated MIC indication indicates that said calculated local MIC is different from said MIC in said received data packet.

17. The system according to claim 12, wherein said secret Encryption Key is derived from a random number sequence.

18. The system according to claim 17, wherein said one or more processors and/or circuits are operable to generate said random number sequence by a random number generator fed with seed entropy from multiple entropy pools comprising an analog-to-digital convertor (ADC) entropy pool and a low power oscillator (LPO) entropy pool.

19. The system according to claim 18, wherein said ADC entropy pool and said LPO entropy pool are formed from occasional and/or unlikely events on an analog-to-digital convertor (ADC) and on a low power oscillator (LPO).

20. The system according to claim 18, wherein said random number sequence comprises a 32-bit, 64-bit, or 128-bit random number sequence for said secret Encryption Key.