Exploratory polling for periodic traffic sources
View Patent ↗An apparatus and method for polling stations that transmit periodic traffic streams are disclosed. A station transmits a polling request that specifies the temporal period of the station's traffic stream, and a coordinator, after receiving the polling request, repeatedly sends polls to the station in a rapid-fire manner until a response from the station is received. The coordinator estimates the temporal offset for the temporal period based on one or both of (i) the time at which the coordinator received the response, and (ii) the time at which the coordinator transmitted the particular poll to which the station responded. Based on the temporal period and temporal offset, the coordinator establishes a polling schedule that polls the station soon after the station generates a frame. The coordinator also monitors downlink traffic to polled stations and, when the downlink traffic is periodic, establishes a downlink transmission schedule accordingly.
1. A method comprising:
(a) receiving a polling request that specifies a first temporal period for a plurality of expected future transmissions;
(b) transmitting a plurality of polls to the sender of said polling request;
(c) receiving a response to at least one of said plurality of polls;
(d) estimating a first temporal offset for said first temporal period based on at least one of:
(i) when said response was received, and
(ii) when at least one of said plurality of polls was transmitted; and
(e) establishing a polling schedule based on said first temporal period and said first temporal offset wherein the temporal offset for the temporal period reduces a delay between when a station queues a frame and when a station transmits a frame;
(f) receiving a plurality of frames for forwarding to said sender of said polling request;
(g) determining whether the arrival times of said frames are in accordance with a second temporal offset and a second temporal period; and
(h) establishing, when said arrival times are in accordance with said second temporal offset and said second temporal period, a transmission schedule for transmitting each of said frames to said sender of said polling request;
wherein said transmission schedule is based on said second temporal offset and said second temporal period wherein said second response is used since said second response may not include a time required to gain contention based access to a shared communications channel while said first response may include a time required to gain contention based access to a shared communications channel.
2. The method of claim 1 further comprising
(j) transmitting:
(i) each of said frames to said sender of said polling request in accordance with said transmission schedule, and
(ii) a poll to said sender of said polling request in accordance with said polling schedule.
3. The method of claim 1 further comprising (j) combining said polling schedule and said transmission schedule into a composite schedule, wherein the composite schedule avoids collisions between the polling schedule and the transmission schedule if said polling schedule and said transmission schedule were used alone.
4. The method of claim 3 wherein said combining said polling schedule and said transmission schedule into a composite schedule further comprises:
determining whether any transmission events are scheduled that would collide with any polling events; and
when a transmission event would collide with a polling event then scheduling said transmission event to a time which would not collide with a polling event.
5. The method of claim 1 wherein said transmitting and said receiving are via a shared-communications channel.
6. A method comprising:
(a) receiving a polling request that specifies a first temporal period for a plurality of expected future transmissions;
(b) transmitting a first poll to the sender of said polling request;
(c) receiving a first response to said first poll;
(d) transmitting a second poll to said sender of said polling request;
(e) receiving a second response to said second poll;
(f) estimating a first temporal offset for said first temporal period based on at least
(i) when said second response was received, and
(ii) when said second poll was transmitted; and
(g) establishing a polling schedule based on said first temporal period and said first temporal offset wherein the temporal offset for the temporal period reduces a delay between when a station queues a frame and when a station transmits a frame;
(h) receiving a plurality of frames for forwarding to said sender of said polling request;
(i) determining whether the arrival times of said frames are in accordance with a second temporal offset and a second temporal period; and
(j) establishing, when said arrival times are in accordance with said second temporal offset and said second temporal period, a transmission schedule for transmitting each of said frames to said sender of said polling request wherein said second response is used since said second response may not include a time required to gain contention based access to a shared communications channel while said first response may include a time required to gain contention based access to a shared communications channel;
wherein said transmission schedule is based on said second temporal offset and said second temporal period.
7. The method of claim 6 further comprising
(k) transmitting:
(i) each of said frames to said sender of said polling request in accordance with said transmission schedule, and
(ii) a poll to said sender of said polling request in accordance with said polling schedule.
8. The method of claim 6 further comprising combining said polling schedule and said transmission schedule into a composite schedule wherein the composite schedule avoids collisions between the polling schedule and the transmission schedule if said polling schedule and said transmission schedule were used alone.
9. The method of claim 8 wherein said combining said polling schedule and said transmission schedule into a composite schedule further comprises:
determining whether any transmission events are scheduled that would collide with any polling events; and
when a transmission event would collide with a polling event then scheduling said transmission event to a time which would not collide with a polling event.
10. An apparatus comprising;
(a) a receiver for receiving a polling request that specifies a first temporal period for a plurality of expected future transmissions;
(b) a transmitter for transmitting a plurality of polls to the sender of said polling request;
(c) a processor for estimating a first temporal offset for said first temporal period based on at least one of:
(i) when said response was received, and
(ii) when at least one of said plurality of polls was transmitted; and
wherein said processor is also for establishing a polling schedule based on said first temporal period and said first temporal offset wherein the temporal offset for the temporal period reduces a delay between when a station queues a frame and when a station transmits a frame;
wherein said receiver is also for receiving a plurality of frames for forwarding to said sender of said polling request; and wherein said processor is also for
(iii) determining whether the arrival times of said frames are in accordance with a second temporal offset and a second temporal period, and
(iv) establishing, when said arrival times are in accordance with said second temporal offset and said second temporal period, a transmission schedule based on said second temporal offset and said second temporal period for transmitting each of said frames to said sender of said polling request wherein said second response is used since said second response may not include a time required to gain contention based access to a shared communications channel while said first response may include a time required to gain contention based access to a shared communications channel.
11. The apparatus of claim 10 wherein said transmitter is also for transmitting
(i) each of said frames to said sender of said polling request in accordance with said transmission schedule, and
(ii) a poll to said sender of said polling request in accordance with said polling schedule.
12. The apparatus of claim 10 wherein said processor is also for combining said polling schedule and said transmission schedule into a composite schedule wherein the composite schedule avoids collisions between the polling schedule and the transmission schedule if said polling schedule and said transmission schedule were used alone.
13. The apparatus of claim 12 wherein said combining said polling schedule and said transmission schedule into a composite schedule further comprises:
determining whether any transmission events are scheduled that would collide with any polling events; and
when a transmission event would collide with a polling event then scheduling said transmission event to a time which would not collide with a polling event.
14. The apparatus of claim 10 wherein said transmitter transmits via a shared-communications channel, and wherein said receiver receives via said shared-communications channel.
15. An apparatus comprising:
(a) a transceiver for:
(i) receiving a polling request that specifies a first temporal period for a plurality of expected future transmissions,
(ii) transmitting a first poll to the sender of said polling request
(iii) receiving a first response to said first poll,
(iv) transmitting a second poll to said sender of said polling request, and
(v) receiving a second response to said second poll;
(b) a processor for estimating a first temporal offset for said first temporal period based on at least one of:
(i) when said second response was received, and
(ii) when said second poll was transmitted wherein the temporal offset for the temporal period reduces a delay between when a station queues a frame and when a station transmits a frame; and
wherein said processor is also for establishing a polling schedule based on said first temporal period and said first temporal offset wherein the temporal offset for the temporal period reduces a delay between when a station queues a frame and when a station transmits a frame;
wherein said receiver is also for receiving a plurality of frames for forwarding to said sender of said polling request; and wherein said processor is also for:
(iii) determining whether the arrival times of said frames are in accordance with a second temporal offset and a second temporal period, and
(iv) establishing, when said arrival times are in accordance with said second temporal offset and said second temporal period, a transmission schedule for transmitting each of said frames to said sender of said polling request wherein said transmission schedule is based on said second temporal offset and said second temporal period.