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 packets in a communications system comprising:
encoding and transmitting a start-of-packet indicator, said start-of-packet indicator being encoded with a first pseudo-noise code (PN-code) word, wherein the start-of-packet indicator comprises two instances of the first PN-code word; and
encoding and transmitting data, said data being encoded with a second PN-Code code word, wherein the communications system comprises a plurality of transmitters and each transmitter uses a different first PN-code word and the same second PN-code word.
2. The method of claim 1 , including encoding and transmitting an end-of-packet indicator, said end-of packet indicator being encoded with said first PN-code word.
3. The method of claim 1 , wherein the communications system is a direct sequence spread spectrum system.
4. The method of claim 1 , wherein the end of packet indicator comprises an inverse of the first PN-code word.
5. The method of claim 1 , wherein the start-of-packet indicator comprises the first PN-code word and the end-of-packet indicator comprises the inverse of the first PN-code word.
6. The method of claim 1 , wherein the start-of-packet indicator includes a packet type identifier.
7. The method of claim 1 , wherein the communications system comprises a plurality of transmitters and each transmitter uses the same first PN-code word and a different second PN-code word.
8. A computer readable medium having stored thereon instructions, which when executed by a processor, cause the processor to perform the method recited in claim 1 .
9. A system for transmitting data over a communications channel comprising:
a transmitter that transmits data packets over said communications channel by transmitting a start-of-packet indicator encoded with a first pseudo-noise code (PN-code) word, followed by data encoded with a second PN-code word, wherein the start-of-packet indicator comprises two instances of the first PN-code word; and
a receiver that receives data packets from said communications channels and that decodes said start-of-packet indicator using said first PN-code word, and said data using said second PN-code word,
wherein there is a plurality of transmitters and the first PN-code word is different for each transmitter and the second PN-code word is the same for all the transmitters.
10. The system of claim 9 , wherein said transmitter transmits an end-of-packet indicator encoded with a first PN-code word after said data is transmitted, and
said receiver determines that the transmission of a packet is complete by detecting an end-of-packet indicator coded using said first PN-code work.
11. The system of claim 9 , wherein the system for communications is a direct sequence spread spectrum system.
12. The system of claim 9 , wherein the receiver further sends an acknowledgement to the transmitter comprising a single instance of the first PN-code word and a single instance of the inverse of the first PN-code word.
13. The system of claim 10 , wherein the end-of-packet indicator comprises one instance of the inverse of said first PN-code word.
14. The system of claim 9 , wherein there is a plurality of transmitters and the second PN-code word is different for each transmitter and the first PN-code word is the same for all the transmitters.
15. A method of framing packets in a communications system comprising:
encoding and transmitting a start-of-packet indicator, said start-of-packet indicator being encoded with a first pseudo-noise code (PN-code) word; and
encoding and transmitting data, said data being encoded with a second PN-Code code word, wherein the communications system comprises a plurality of transmitters and each transmitter of the plurality of transmitters uses a different first PN-code word and the same second PN-code word.
16. The method of claim 15 , wherein the communications system is a direct sequence spread spectrum system.
17. The method of claim 15 , wherein the start-of-packet indicator includes a packet type identifier.
18. A system for transmitting data over a communications channel comprising:
a first transmitter of a plurality of transmitters that transmits data packets over said communications channel by transmitting a start-of-packet indicator encoded with a first pseudo-noise code (PN-code) word, followed by data encoded with a second PN-code word, wherein the second PN-code word is different for each transmitter of the plurality of transmitters and the first PN-code word is the same for all transmitters of the plurality of transmitters; and
a receiver that receives data packets from said communications channels and that decodes said start-of-packet indicator using said first PN-code word, and said data using said second PN-code word.
19. The system of claim 18 , wherein said first transmitter transmits an end-of-packet indicator encoded with a first PN-code word after said data is transmitted, and wherein said receiver determines that the transmission of a packet is complete by detecting an end-of-packet indicator coded using said first PN-code word.
20. The system of claim 19 , wherein the end-of-packet indicator comprises one instance of the inverse of said first PN-code word.