Random timing offset determination
Methods, systems and instructions stored on computer-readable media for generating, at a first node, a plurality of data units. The plurality of data units are spread with a common pseudo-noise (PN) code that is used by a plurality of nodes, including the first node and a second node, that are in communication with an access point. A random timing offset is determined, and a first data unit is transmitted to the access point at a first time based upon a slot start time and the random timing offset. The first data unit is transmitted while at least a portion of a second signal is transmitted from the second node such that both the first data unit and the second signal are received by the access point. The second signal is transmitted at a second time based on the slot time and a second random timing offset.
1. A method comprising:
generating, using a processor at a first node, a plurality of data units;
spreading the plurality of data units with a common pseudo-noise (PN) code, wherein the common PN code is used by a plurality of nodes, including the first node and a second node, that are in communication with an access point;
determining a random timing offset; and
transmitting a first data unit to the access point at a first time based upon a slot start time and the random timing offset, wherein the first data unit is transmitted while at least a portion of a second signal is transmitted from the second node such that both the first data unit and the second signal are received by the access point, and wherein the second signal is transmitted at a second time based on the slot time and a second random timing offset.
2. The method of claim 1 , wherein determining the random timing offset comprises using a pseudo-random number generator.
3. The method of claim 2 , further comprising:
determining a seed value based on one or more of a node identifier of the first node, an access point identifier, a MAC identifier of the first node, a connection identifier, an asymmetric security key, a connection frame number, a system frame number, and a counter; and
seeding the pseudo-random number generator with the seed.
4. The method of claim 1 , wherein determining the random timing offset comprises hashing a value comprising a system parameter.
5. The method of claim 4 , wherein the value comprises one or more of a node identifier of the first node, an access point identifier, a MAC identifier of the first node, a connection identifier, an asymmetric security key, a connection frame number, a system frame number, and a counter.
6. The method of claim 1 , further comprising determining a new random timing offset for each data unit that is transmitted.
7. The method of claim 1 , wherein the random timing offset is known to the access point but is not transmitted to the access point from the first node.
8. The method of claim 7 , wherein the access point calculates an expected timing offset of the first data unit and a received timing offset of the first data unit, wherein the access point calculates a propagation delay based on the expected timing offset and the received timing offset; and wherein the access point calculates a distance of the first node from the access point based upon the propagation delay.
9. The method of claim 1 , wherein the access point calculates an expected and actual random timing offset for the data unit and drops the data unit if the expected random timing offset is not equal to the actual random timing offset.
10. The method of claim 1 , further comprising determining a sub-slot, wherein the first time is further based upon a sub-slot start time.
11. The method of claim 10 , wherein determining a sub-slot comprises using a pseudo-random number generator.
12. The method of claim 10 , wherein determining a sub-slot comprises hashing a value comprises a system parameter.
13. A non-transitory computer-readable medium, at a first node, having instructions stored thereon, the instructions comprising:
instructions to generate a plurality of data units;
instructions to spread the plurality of data units with a common pseudo-noise (PN) code, wherein the common PN code is used by a plurality of nodes, including the first node and a second node, that are in communication with an access point;
instructions to determine a random timing offset; and
instructions to transmit a first data unit to the access point at a first time based upon a slot start time and the random timing offset, wherein the first data unit is transmitted while at least a portion of a second signal is transmitted from the second node such that both the first data unit and the second signal are received by the access point, and wherein the second signal is transmitted at a second time based on the slot time and a second random timing offset.
14. The non-transitory computer-readable medium of claim 13 , wherein the instructions to determine the random timing offset comprise instructions to use a pseudo-random number generator.
15. The non-transitory computer-readable medium of claim 14 , further comprising:
instructions to determine a seed value based on one or more of a node identifier of the first node, an access point identifier, a MAC identifier of the first node, a connection identifier, an asymmetric security key, a connection frame number, a system frame number, and a counter; and
instructions to seed the pseudo-random number generator with the seed.
16. The non-transitory computer-readable medium of claim 13 , wherein the instructions to determine the random timing offset comprise instructions to hash a value comprising a system parameter.
17. A first node comprising:
one or more electronic processors configured to:
generate a plurality of data units;
spread the plurality of data units with a common pseudo-noise (PN) code, wherein the common PN code is used by a plurality of nodes, including the first node and a second node, that are in communication with an access point; and
determine a random timing offset; and
a transmitter configured to:
transmit a first data unit to the access point at a first time based upon a slot start time and the random timing offset, wherein the first data unit is transmitted while at least a portion of a second signal is transmitted from the second node such that both the first data unit and the second signal are received by the access point, and wherein the second signal is transmitted at a second time based on the slot time and a second random timing offset.
18. The system of claim 17 , wherein the one or more electronic processors are further configured to determine the random timing offset by using a pseudo-random number generator.
19. The system of claim 18 , wherein the one or more electronic processors are further configured to:
determine a seed value based on one or more of a node identifier of the first node, an access point identifier, a MAC identifier of the first node, a connection identifier, an asymmetric security key, a connection frame number, a system frame number, and a counter; and
seed the pseudo-random number generator with the seed.
20. The system of claim 17 , wherein the one or more electronic processors are further configured to determine the random timing offset by hashing a value comprising a system parameter.