Frequency offset differential pulse position modulation
View Patent ↗The present invention provides such a need by utilizing a frequency offset differential pulse position modulation scheme to transmit data between computing devices within a wireless network system. The differential pulse position modulation component of the scheme enables the present invention to provide relative immunity to interference for the system. In particular, such immunity from interference is achieved by utilizing a blanking time between pulse positions, which is large enough to allow the interference between frequency offset—differential pulse position modulation pulses to subside. The frequency offset component of the scheme enables the system to utilize multiple frequency channels to enable the system to achieve higher data rates. In particular, by utilizing a time offset between the frequency channels, the blanking time can be reduced, thereby increasing the amount of data that can be transmitted with a set period of time.
1. A method for controlling access to a medium comprising:
(a) determining a first transmit time for a packet on a transmission medium based on a non-zero number selected from a random number generator;
(b) at the determined first transmit time, sensing traffic on said transmission medium;
(c) if said transmission medium is available, transmitting the packet; and
(d) if said transmission medium is not available, deferring a transmission of the packet to a second transmit time using a second non-zero number selected from the random number generator.
2. The method of claim 1 , wherein said second transmit time is further based at least in part on an Inter Packet Gap time.
3. The method of claim 1 , further comprising counting a number of instances said transmission of the packet is deferred and deferring said transmission until the number of instances said transmission is deferred reaches a threshold value.
4. The method of claim 3 further comprising:
terminating attempts to transmit the packet based, at least in part, on the number of instances of said transmission reaching said threshold value.
5. The method of claim 1
wherein said second transmit time is further based at least in part on a back-off process in response to said deferral of transmission.
6. The method of claim 1
wherein said second transmit time is further based at least in part on multiplying the second non-zero number by a programmable access-slot time.
7. The method of claim 6 wherein the programmable access-slot time is determined based on a round trip delay time between any sending and receiving pair of nodes accessing the transmission medium.
8. The method of claim 6
wherein the programmable access-slot time includes a transmit turn-on time.
9. The method for of claim 1 , wherein a maximum number selectable from the random number generator is determined based on a counter of a number of instances said transmission of the packet is deferred.
10. The method of claim 5
wherein the back-off process is a linear back-off process.
11. The method of claim 1 , further comprising repeating (b)-(d) with the second transmit time as the determined first transmit time.
12. An apparatus comprising:
a transmit media access control module configured to
(a) determine a first transmit time for a packet on a transmission medium based on a non-zero number selected from a random number generator;
(b) at the determined first transmit time, sense traffic on said transmission medium;
(c) if said transmission medium is available, trigger transmission of the packet by a transmitter; and
(d) if said transmission medium is not available, defer transmission of the packet to a second transmit time using a second non-zero number selected from the random number generator.
13. The apparatus of claim 12 , wherein said second transmit time is further based at least in part on an Inter Packet Gap time.
14. The apparatus of claim 12 , further comprising counting a number of instances said transmission of the packet is deferred and deferring said transmission until the number of instances said transmission is deferred reaches a threshold value.
15. The apparatus of claim 14 , wherein said transmit media access control module is further configured to terminate attempts to transmit the packet based, at least in part, on the number of instances of said transmission reaching said threshold value.
16. The apparatus of claim 13 , wherein said
second transmit time is further based at least in part on a back-off process in response to said deferral of transmission.
17. The apparatus of claim 12 wherein said second transmit time is further based at least in part on multiplying the second non-zero number by a programmable access-slot time.
18. The apparatus of claim 17 wherein the programmable access-slot time is determined based on a round trip delay time between any sending and receiving pair of nodes accessing the transmission medium.
19. The apparatus of claim 17 , wherein the programmable access-slot time includes a transmit turn-on time.
20. The apparatus of claim 12 wherein a maximum number selectable from the random number generator is determined based on a counter of a number of instances said transmission of the packet is deferred.
21. The apparatus of claim 16 wherein said back-off process is a linear back-off process.
22. The apparatus of claim 12 , further comprising repeating (b)-(d) with the second transmit time as the determined first transmit time.