Collision detection method
A wireless device may receive packets according to a protocol, such as Bluetooth, and may rapidly react to receive an interfering RF packet instead of dropping the first RF packet and the interfering RF packet, to decrease message delay due to collisions in high device density environments. When a received signal strength indicator (RSSI) difference between the interfering RF packet and the first RF packet exceeds a threshold, the device may detect the interfering packet and resync a portion of its circuitry to lock on to and receive the interfering packet. The wireless receiver may detect the interfering RF packet by detecting one or more of: a specific resync byte sequence, an increase in RSSI, or a phase shift. Additionally, a wireless device may add the specific resync byte sequence to an RF packet of a standard protocol.
1. A method comprising:
detecting a first RF packet;
synchronizing to and demodulating the first RF packet to create demodulated bits;
storing the demodulated bits of the first RF packet in a buffer;
during receipt of the first RF packet, detecting a second RF packet;
upon detecting the second RF packet, synchronizing to the second RF packet;
demodulating the second RF packet;
storing the demodulated bits from the second RF packet in the buffer; and
coding a physical layer of a transmitted RF packet to prevent a device from synchronizing to the transmitted RF packet.
2. The method of claim 1 , wherein a bit stream of the coded physical layer comprises no greater than a predetermined number of sequential ones or zeros.
3. The method of claim 1 , wherein:
coding the physical layer comprises replacing a resync byte sequence with the physical layer, and
the resync byte sequence is configured to trigger demodulation of the second RF packet.
4. A device configured to:
detect a first RF packet;
synchronize to and demodulate the first RF packet to create demodulated bits;
store the demodulated bits of the first RF packet in a buffer;
during receipt of the first RF packet, detect a second RF packet;
upon detection of the second RF packet, synchronize to the second RF packet;
demodulate the second RF packet;
store the demodulated bits from the second RF packet in the buffer; and
code a physical layer of a transmitted RF packet to prevent the device from synchronizing to the transmitted RF packet.
5. The device of claim 4 , wherein a bit stream of the coded physical layer comprises no greater than a predetermined number of sequential ones or zeros.
6. The device of claim 4 , wherein:
to code the physical layer comprises to replace a resync byte sequence with the physical layer, and
the resync byte sequence is configured to trigger demodulation of the second RF packet.
7. At least one computer-readable storage medium comprising executable instructions for configuring at least one processor to:
detect a first RF packet;
synchronize to and demodulate the first RF packet to create demodulated bits;
store the demodulated bits of the first RF packet in a buffer;
during receipt of the first RF packet, detect a second RF packet;
upon detection of the second RF packet, synchronize to the second RF packet;
demodulate the second RF packet;
store the demodulated bits from the second RF packet in the buffer; and
code a physical layer of a transmitted RF packet to prevent a device from synchronizing to the transmitted RF packet.
8. The at least on computer-readable storage medium of claim 7 , wherein a bit stream of the coded physical layer comprises no greater than a predetermined number of sequential ones or zeros.
9. The at least on computer-readable storage medium of claim 7 , wherein:
to code the physical layer comprises to replace a resync byte sequence with the physical layer, and
the resync byte sequence is configured to trigger demodulation of the second RF packet.
10. The method of claim 1 , wherein the second RF packet comprises a resync byte sequence, the method further comprising detecting the second RF packet by detecting the resync byte sequence.
11. The method of claim 10 , wherein the second RF packet comprises a preamble, the resync byte sequence prior to the preamble, and a payload subsequent to the preamble.
12. The method of claim 1 , further comprising detecting the second RF packet by detecting an increase in a received signal strength indicator (RSSI) greater than or equal to a threshold during the receipt of the first RF packet.
13. The method of claim 1 , further comprising detecting the second RF packet by detecting a phase shift in one or more data symbols during the receipt of the first RF packet.
14. The device of claim 4 , wherein:
the second RF packet comprises a resync byte sequence; and
to detect the second RF packet comprises to detect the resync byte sequence.
15. The device of claim 14 , wherein the second RF packet comprises a preamble, the resync byte sequence prior to the preamble, and a payload subsequent to the preamble.
16. The device of claim 4 , wherein to detect the second RF packet comprises to detect an increase in a received signal strength indicator (RSSI) greater than or equal to a threshold during the receipt of the first RF packet.
17. The device of claim 4 , wherein to detect the second RF packet comprises to detect a phase shift in one or more data symbols during the receipt of the first RF packet.
18. The at least on computer-readable storage medium of claim 7 , wherein:
the second RF packet comprises a resync byte sequence; and
to detect the second RF packet comprises to detect the resync byte sequence.
19. The at least on computer-readable storage medium of claim 7 , wherein to detect the second RF packet comprises to detect an increase in a received signal strength indicator (RSSI) greater than or equal to a threshold during the receipt of the first RF packet.
20. The at least on computer-readable storage medium of claim 7 , wherein to detect the second RF packet comprises to detect a phase shift in one or more data symbols during the receipt of the first RF packet.