1. < November, 2011 >
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Improved Low Energy Mechanism based on 4e MAC_WSNIRI]
Date Submitted: [9 November, 2011]
Source: [Yang Yang1, Xiang Wang1, Heqing Huang1, Jie Shen1, Tao Xing1,2, Haitao Liu1]
Company [Wuxi SensingNet Industrialization Research Institute1 , SIMIT2]
Address [No.767, Jinzhong Rd, Shanghai, China]
Voice:[ ], FAX: [ ] E-
Re: [Call for Proposals, DCN: , 10 May, 2011]
Abstract: [This document proposed low energy mechanism based on 4e MAC to support implementation of k.]
Purpose: [Proposal for consideration of inclusion into k.]
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P

2. Low Energy Mechanism based on 4e MAC
< November, 2011 >
Low Energy Mechanism based on 4e MAC
09-Nov-2011

3. Outline Characteristic of 4k network
< November, 2011 >
Outline
Characteristic of 4k network
What MAC Mechanism We Should Provide
Why Asynchronous
Low Energy Mode in 4e
Proposed Low Energy MAC for 4k
Summary

4. Characteristic of 4k Network
< November, 2011 >
Characteristic of 4k Network
k-technical-guidance-document
point to multi-thousands of points communications
asymmetric link
more data from end-point to coordinator
for end point, don’t communicate directly with each other, need low energy operation necessary for multi-year battery life (>20 year)
for coordinator, mains powered
enable the collection of scheduled and event data
small, infrequent messages
tolerant of data latency
as data duration may be very long, channel condition may be varying during packet transmission
power consumption are the major design requirement

5. What MAC Mechanism We Should Provide
< November, 2011 >
What MAC Mechanism We Should Provide
some analysis of synchronous network
higher transmission successful rate
but should consider power consumption lower limitation
need periodically listen for beacon or exchange frames for synchronization
consider tradeoff between synchronization accuracy and power consumption
need prior time slot allocation processing
pre-allocation slots dynamic consideration
frames exchange to reserve slots more transmission consumption
design goal: minimize active time, minimize overhead
suggest to provide asynchronous mechanism in 4k
when the network consumption is very strict

6. Why Asynchronous asynchronous MAC for characteristic of 4k network
< November, 2011 >
Why Asynchronous
asynchronous MAC
advantage: can reach very low power consumption
disadvantage: transmission may conflict
for characteristic of 4k network
maybe we have hidden terminal problem, near-far problem… but as the daily scheduled data transmission requirement is very low, the conflict probability will be very small, even though transmission failed, consumption of retransmission will not be very high
end point can send event data immediately, latency of event data will be lower than TDMA
varying and lossy environment will make the network dynamic, in asynchronous network, end points join or leave will be very easily, with the lowest interruption to the existing communications, and don’t need to coordinate the slot distribution
keep the lowest active duty, transmission of end point will hard to be interrupted or make interference to other coexisting networks

7. Low Energy Mode in 4e (1) Coordinated Sampled Listening (CSL)
< November, 2011 >
Low Energy Mode in 4e (1)
Coordinated Sampled Listening (CSL)
receiver periodically performs channel sampling for radio traffic
sender transmits wakeup frame sequence prior to payload frame

8. Low Energy Mode in 4e (2) Receiver Initiated Transmission (RIT)
< November, 2011 >
Low Energy Mode in 4e (2)
Receiver Initiated Transmission (RIT)
receiver periodically broadcasts dataReq frames and listen for a short amount of time for incoming transmissions every macRitPeriod
sender waits until receiving dataReq frame from receiver then immediately transmit payload frame

9. Low Energy Mode in 4e (3) wake-up mechanism shall be improved
< November, 2011 >
Low Energy Mode in 4e (3)
wake-up mechanism shall be improved
in 4k applications, frame send by coordinator mainly should be broadcast frame, like configuration frame, RIT mode not support broadcast
if coordinator use CSL mode directly, each time coordinator want to send a frame, even it just want to wake up one end point, during the wake up duration, all nodes in network can’t communicate

10. Proposed Low Energy MAC for 4k (1)
< November, 2011 >
Proposed Low Energy MAC for 4k (1)
based on non-beacon mechanism in 15.4
end point
listen the channel periodically, other time keep sleeping
if has data to transmit, send frame by using CSMA/CA
without receiving Ack, retransmit the frame
collector
main powered, keep listening for the channel
if coordinator has unicast frame to send, after receiving frame from the corresponding end point, send the frame as Ack for the frame

11. Proposed Low Energy MAC for 4k (2)
< November, 2011 >
Proposed Low Energy MAC for 4k (2)
when collector has high QoS lever frame or emergency frame need to send to endpoint, collector need to wakeup end point
end point
listen the channel periodically, for being available to be woke up by collector
collector
send wakeup sequence
{wakeup frame + interval of wakeup frames}
indicate the unicast/broadcast type of the next frame in wakeup frame

12. Proposed Low Energy MAC for 4k (3)
< November, 2011 >
Proposed Low Energy MAC for 4k (3)
if the high QoS level data or emergency data is unicast
destination address of wakeup frame is the address of the corresponding end point
on receipt of wakeup frame, end point send data request frame
on receipt of data request frame, collector stop sending wakeup sequence, and send corresponding data frame immediately

13. Proposed Low Energy MAC for 4k (4)
<month year>
doc.: IEEE <doc#>
< November, 2011 >
Proposed Low Energy MAC for 4k (4)
if the high QoS level data or emergency data is broadcast or multicast
destination address of wakeup frame is the broadcast address,
on receipt of wakeup frame, end point send data request frame, then turn on RX at the designated time for receiving data from collector
on receipt of data request frames from all the corresponding end points, collector stop sending wakeup sequence, and send corresponding data frame at the designated time
<author>, <company>

14. Proposed Low Energy MAC for 4k (5)
< November, 2011 >
Proposed Low Energy MAC for 4k (5)
support topology: star topology
4k applications need point to multi-thousand points communications, and end point don’t communicate directly with each other
star topology may be the best choice
can support dynamic network
end point join or leave the network will be easy

15. Summary focus on the characteristic of 4k
< November, 2011 >
Summary
focus on the characteristic of 4k
analyze advantages and disadvantages of synchronous network and asynchronous network, suggest to provide asynchronous mechanism as 4k MAC consideration
analyze the low energy mode in 4e
for unicast normal data, keep the lowest end point active duration
supply improved wakeup mechanism, to support high QoS level frame or emergency frame communication
support star topology
give the message chart of proposed MAC
corresponding modification of MAC
welcome to be improved by merging with other proposals or further discussion

16. < November, 2011 >
Thank you!