Method for providing packet framing in a communication system
An improved method of framing data packets in a direct sequence spread spectrum (DSSS) system that uses one pseudo-noise code (PN-Code) to frame the packet with a start-of-packet (SOP) and end-of-packet (EOP) indicator, and a different PN-Code to encode the data payload. Furthermore, the SOP is represented by the framing PN-Code, and the EOP is represented by the inverse of the framing PN-Code. This method creates a robust framing system that enables a DSSS system to operate with a low threshold of detection, thus maximizing transmission range even in noisy environments. Additionally, the PN-Code used for the SOP and EOP indicators can be used to indicate an acknowledgement response.
1. A method of framing a packet comprising:
encoding and transmitting a first start-of-packet indicator by a first transmitter and a second start-of-packet indicator by a second transmitter, wherein the first start-of-packet indicator is encoded with a first pseudo-noise code (PN-code) word and the second start-of-packet indicator is encoded with a second PN-code word; and
encoding and transmitting first data by the first transmitter and second data by the second transmitter, wherein the first data and second data are both encoded with a third PN-code word, and wherein the first PN-code word, the second PN-code word, and the third PN-code word each comprise a different PN-code word.
2. The method of claim 1 , further comprising:
encoding and transmitting a third start-of-packet indicator by a third transmitter, wherein the third start-of-packet indicator is encoded with the first PN-code word.
3. The method of claim 2 , further comprising:
encoding and transmitting third data by the third transmitter, wherein the third data is also encoded with the third PN-code word.
4. The method of claim 1 , further comprising:
encoding and transmitting a third start-of-packet indicator by a third transmitter, wherein the third start-of-packet indicator is encoded with the second PN-code word.
5. The method of claim 4 , further comprising:
encoding and transmitting third data by the third transmitter, wherein the third data is also encoded with the third PN-code word.
6. The method of claim 1 , wherein the first and second transmitters are each direct sequence spread spectrum transmitters.
7. The method of claim 1 , wherein the first start-of-packet indicator comprises an instance of the first PN-code word and an instance of a derivative of the first PN-code word.
8. The method of claim 7 , wherein the derivative of the first PN-code word comprises an inverse of the first PN-code word.
9. A computer readable storage medium having stored thereon instructions, which when executed by a processor, cause the processor to perform the method recited in claim 1 .
10. A system for transmitting a packet comprising:
a first transmitter configured to transmit a first start-of-packet indicator encoded with a first pseudo-noise code (PN-code) word followed by first data encoded with a third PN-code word, wherein the first PN-code word is different from a second PN-code word used by a second transmitter to encode a second start-of-packet indicator and the third PN-code word is the same as the third PN-code word used by the second transmitter to encode second data; and
a receiver configured to receive the packet from the first transmitter and to decode the first start-of-packet indicator using the first PN-code word and to decode the first data using said third PN-code word.
11. The system of claim 10 , further comprising:
a third transmitter configured to transmit a third start-of-packet indicator encoded with the first PN-code word.
12. The system of claim 10 , wherein the receiver is configured to decode the second start-of-packet indicator using the second PN-code word.
13. The system of claim 10 , wherein a third transmitter is configured to transmit a third start-of-packet indicator encoded with the first PN-code.
14. The system of claim 10 , wherein the first and second transmitters are each a direct sequence spread spectrum transmitters.
15. The system of claim 10 , wherein the receiver is configured to send an acknowledgment to the first transmitter comprising an instance of the first PN-code word and an instance of a derivative of the first PN-code word.
16. The system of claim 10 , wherein the first start-of-packet indicator comprises two instances of the first PN-code word.
17. The system of claim 10 , wherein the first start-of-packet indicator comprises an instance of the first PN-code word and an instance of a derivative of the first PN-code word.
18. The system of claim 17 , wherein the derivative of the first PN-code word comprises an inverse of the first PN-code word.
19. A method of framing a packet comprising:
encoding and transmitting a first start-of-packet indicator by a first transmitter, said first start-of-packet indicator being encoded with a first pseudo-noise code (PN-code) word, wherein the first PN-code word is different from a second PN-code word used by a second transmitter, wherein the packet comprises an instance of the first PN-code word and an instance of a derivative of the first PN-code word; and
encoding and transmitting first data, said first data being encoded with a third PN-code word, wherein the third PN-code word is the same as the third PN-code word used by the second transmitter.
20. The method of claim 19 , wherein the derivative of the first PN-code word comprises an inverse of the first PN-code word.