Allocation slot arrangement for wireless body area networks with sensor initiated grant extensions
Allocation slot arrangement is provided for wireless body area networks (BANs). In particular, in some embodiments the allocation slots are arranged based on a set of rules and received input parameters. Allocation slot arrangement may comprise maximizing a weighted sum function computed by applying the rules and input parameters to all nodes over all possible arrangements.
1. A method of arranging a plurality of allocation slots, wherein each of the plurality of allocation slots has been allocated to a respective one of a plurality of nodes in a body area network (BAN), the method comprising:
receiving at a BAN hub a set of input parameters corresponding to the plurality of nodes, wherein the input parameters comprise a Sensor-initiated Grant extension (SIGE) probability and a SIGE length distribution of one of the plurality of nodes, wherein the SIGE is an extension of an allocation slot duration beyond a granted allocation slot duration;
setting rules that each of the plurality of nodes must follow in the BAN network; and
selecting an allocation slot arrangement of the plurality of allocation slots based on the input parameters and the rules, wherein the BAN hub selects the allocation slot arrangement.
2. The method of claim 1 wherein selecting the allocation slot arrangement based on the input parameters and the rules further comprises:
calculating a normalized utility metric for each of the plurality of nodes for the allocation slot arrangement, wherein the normalized utility metric represents the expected realizable allocation slot length of a node, normalized by its initially scheduled allocation slot length;
computing a weighted sum for the allocation slot arrangement based on the calculated utility metrics; and
selecting the allocation slot arrangement if the computed weighted sum maximizes a weighted sum function.
3. The method of claim 2 wherein the calculation of the normalized utility metric for each of the plurality of nodes in the allocation slot arrangement is based on the rules and the input parameters.
4. The method of claim 3 wherein the allocation slot arrangement comprises the order of the allocation slots, any gaps between the allocation slots, and any gaps between the allocation slots and boundaries of a reserved period for the allocation slots.
5. The method of claim 4 wherein the input parameters comprise a maximum length of the reserved period, emergency event parameters, and characteristics of each of the plurality of nodes.
6. The method of claim 5 wherein the input parameters comprise a weight factor of each of the plurality of nodes.
7. The method of claim 6 wherein the weight factor of each of the plurality of nodes is based on the node's respective Quality of Service (“QOS”) latency and reliability requirements.
8. The method of claim 1 wherein the input parameters comprise a scheduled allocation slot length, a reschedule tolerance threshold, a SIGE probability, and a SIGE length distribution of each of the plurality of nodes.
9. The method of claim 2 wherein the weighted sum function comprises a plurality of weighted sums calculated for each of a plurality of allocation slot arrangements.
10. The method of claim 6 wherein the weighted sum function comprises the plurality of weight factors corresponding to each of the plurality of nodes.
11. The method of claim 4 wherein the rules comprise the requirement that a node can wake up only once during a reserved period.
12. The method of claim 1 wherein the rules comprise at least one of the following requirements:
if an awakened node is not polled at the start of its allocated slot by the BAN hub, the awakened node may keep awake for a maximum of the awakened node's reschedule tolerance threshold;
a node's reschedule tolerance threshold (R n ) is less than its scheduled allocation slot length (l n ); and
if a node is polled within x <R n , of it awakening, the polled node is granted an allocation slot length of min(l n , l n +U n x , wherein U n x is the distance of the polled node's allocation slot end time from a no pass zone when its start time is delayed by x positive seconds, wherein the no pass zone is a beginning of an unreserved period.
13. The method of claim 4 , further comprising the BAN hub broadcasting to the plurality of nodes a message containing the selected allocation slot arrangement.
14. The method of claim 12 wherein the rules comprise the requirement that if a node is polled within x <R n of it awakening, the polled node is granted an allocation slot length of min(l n, l n +U n x ), wherein U n x is the distance of the polled node's allocation slot end time from a no pass zone when its start time is delayed by x positive seconds, wherein the no pass zone is a beginning of an unreserved period.
15. A network device configured to perform a method of arranging a plurality of allocation slots, wherein each of the plurality of allocation slots has been allocated to a respective one of a plurality of nodes in a body area network (BAN), the network device comprising:
one or more processors;
one or more non-transitory computer-readable mediums operatively coupled to at least one of the one or more processors and having instructions stored thereon that, when executed by at least one of the one or more processors, cause at least one of the one or more processors to:
receive a set of input parameters corresponding to the plurality of nodes, wherein the input parameters comprise a Sensor-initiated Grant extension (SIGE) probability and a SIGE length distribution of one of the plurality of nodes, wherein the SIGE is an extension of an allocation slot duration beyond a granted allocation slot duration;
set rules that each of the plurality of nodes must follow in the BAN network; and
select an allocation slot arrangement of the plurality of allocation slots based on the input parameters and the rules.
16. The network device of claim 15 , wherein selecting the allocation slot arrangement based on the input parameters and the rules further comprises:
calculating a normalized utility metric for each of the plurality of nodes for the allocation slot arrangement, wherein the normalized utility metric represents the expected realizable allocation slot length of a node, normalized by its initially scheduled allocation slot length;
computing a weighted sum for the allocation slot arrangement based on the calculated utility metrics; and
selecting the allocation slot arrangement if the computed weighted sum maximizes a weighted sum function.
17. The network device of claim 16 wherein the calculation of the normalized utility metric for each of the plurality of nodes in the allocation slot arrangement is based on the rules and the input parameters.
18. The network device of claim 17 wherein the allocation slot arrangement comprises the order of the allocation slots, any gaps between the allocation slots, and any gaps between the allocation slots and boundaries of a reserved period for the allocation slots.
19. The network device of claim 18 wherein the input parameters comprise a maximum length of the reserved period, emergency event parameters, and characteristics of each of the plurality of nodes.
20. The network device of claim 19 wherein the input parameters comprise a weight factor of each of the plurality of nodes.
21. The network device of claim 20 wherein the weight factor of each of the plurality of nodes is based on the node's respective Quality of Service (“QOS”) latency and reliability requirements.
22. The network device of claim 15 wherein the input parameters comprise a scheduled allocation slot length, a reschedule tolerance threshold, a SIGE probability, and a SIGE length distribution of each of the plurality of nodes.
23. The network device of claim 16 wherein the weighted sum function comprises a plurality of weighted sums calculated for each of a plurality of allocation slot arrangements.
24. The network device of claim 20 wherein the weighted sum function comprises the plurality of weight factors corresponding to each of the plurality of nodes.
25. The network device of claim 18 wherein the rules comprise the requirement that a node can wake up only once during a reserved period.
26. The network device of claim 15 wherein the rules comprise at least one of the following requirements:
if an awakened node is not polled at the start of its allocated slot by the BAN hub, the awakened node may keep awake for a maximum of the awakened node's reschedule tolerance threshold;
a node's reschedule tolerance threshold (R n ) is less than its scheduled allocation slot length (l n ); and
if a node is polled within x <R n , of it awakening, the polled node is granted an allocation slot length of min(l n , l n +U n x ), wherein U n x is the distance of the polled node's allocation slot end time from a no pass zone when its start time is delayed by x positive seconds, wherein the no pass zone is a beginning of an unreserved period.
27. The network device of claim 18 , further comprising a transceiver configured to broadcast to the plurality of nodes a message containing the allocation slot arrangement.
28. The network device of claim 26 wherein the rules comprise the requirement that if a node is polled within x <R n of it awakening, the polled node is granted an allocation slot length of min(l n , l n +U n x ), wherein U n x is the distance of the polled node's allocation slot end time from a no pass zone when its start time is delayed by x positive seconds, wherein the no pass zone is a beginning of an unreserved period.
29. The network device of claim 18 , wherein the network device is a BAN hub.