1. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [MAC Proposal for Low-Energy Wide Area Monitoring]
Date Submitted: [Sep 15, 2011]
Source: [Seong-Soon Joo, Jong-Arm Jun, Cheol-Sig Pyo]
Company: [ETRI]
Address: [161 Gajeong-dong, Yuseong-gu, Daejeon, KOREA]
Voice: [ ], FAX: [ ],
Re: [IEEE 802 TG4k issues a call for proposal]
Abstract: [A MAC for low-energy wide area monitoring is proposed.]
Purpose: [To contribute the initial process of preparing draft for TG4k]
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
<author>, <company>

2. MAC Proposal for Low-Energy Wide Area Monitoring
<month year>
doc.: IEEE <doc#>
MAC Proposal for Low-Energy Wide Area Monitoring
Seong-Soon Joo*,
Jong-Arm Jun, Cheol-Sig Pyo
ETRI
<author>, <company>

3. Requirements on LECIM MAC
Design goals of wide area monitoring
long lived infra
more than 10 years life like network carrier’s infra
ease maintained monitoring network
high degree of freedom to start the monitoring/maintenance business
Design requirements on LECIM MAC
guaranteed link access on low duty cycle with low energy
minimize contention on a link
support to fair access between near and far nodes
time-stamping
support to ease installation
support to ease maintenance
support to make network structure simple
optimized to network configuration
near node
hidden node
coordinator
far node
contention node

4. Major Contribution Provide a tool for time-stamping
global time synchronization
adjust clock drift with light overhead
Contention-free low energy link access
distribute access loads on slotted link
three grades of link access
Extend reaches of link
echo back a frame
two modes of link repeater
Low-energy link management
management frame from coordinator for optimized configuration and ease maintenance
link power management

5. Time Synchronization in LECIM Network (I)
need time-stamping
times of occurrence of events are crucial for observer
temporal coordination of the sleep periods for low-energy devices
global time synchronization for time-stamping
over-the air synchronization
coordinator is power-free
may have high precision clock
afford to transmit clock information periodically in any time scale
adjust clock drift of a local device based upon coordinator master clock
beacon frame as a global clock tick
need a message to broadcast global clock time
clock leap second is beacon interval
use sequence number of beacon frame for clock sampling
low-energy operation for receiving a beacon
detect clock tick by waiting a beacon on estimated appearance duration with guard time
clock tick interval is selected for balancing the energy consumption and precision of clock

6. Time Synchronization in LECIM Network (II)BI
BI*2Wo
coordinator
device
adjust clock

7. Time Synchronization in LECIM Network (III)
device
adjust clock

8. Slot Based Link Access (I)
link access with low energy
maximize network wide throughput over consumed energy
minimize collision by resource contention, hidden nodes arbitration
reduce overhead in access procedure
synchronous link access
for device time stamping, already have beacon frame and synchronized global clock
for contention-free link access, distribute access loads on slotted link
to support over 1,000 devices, use DSME multi-frame structure
assign a slot to the device
convert device address to assigned slot by using hashing function
assign several candidate slots for a device
slot assignment can be carried in off-line
BI = 2BO *aBaseSuperframeDuration
SD=2SO *aBaseSuperframeDuration
2BO-SO th superframe
beacon
beacon
beacon
beacon
TS 0x00
TS 0x01
TS 0x0f
TS 0x10
TS 0x11
TS 0x1f
16*2BO-SO-1

9. Slot Based Link Access (II)
uplink access methods in a slot
three grades of uplink access
real-time transmission
reliable transmission
loss tolerant transmission
different transmission recovery action
grade 0
at the start of a slot, transmit the frame without CCA, wait for ACK
if failed, retry transmission with CCA and wait for ACK
if failed, retry on next candidate slot
beacon
TS 0x10
TS 0x11
TS 0x1f
TS 0x0f
TS 0x01
TS 0x00
16*2BO-SO-1
coordinator
device
gr0 access
data
ACK
mang

10. Slot Based Link Access (III)
grade 1
at the start of a slot, transmit the frame without CCA
receive ACK/NACK from next beacon or device management frame
if failed, retry transmission with CCA on next candidate slot
grade 2
beacon
TS 0x10
TS 0x11
TS 0x1f
TS 0x0f
TS 0x01
TS 0x00
16*2BO-SO-1
coordinator
device
gr1 access
data
ACK
mang
gr2 access

11. Link Repeater (I) Extend reaches of link Link repeater
varying RF environment from/to coordinator
devices are located sparsely
extend reaches of link from/to coordinator
Link repeater
echo back a frame after receiving a frame from the coordinator or devices
link repeater is power-free or located at ease maintainable place
two modes of link repeater according to the limitation on power resource
coordinator
repeater
device

12. Link Repeater (II) coordinator TS 0x00 TS 0x01 TS 0x0f TS 0x10 TS 0x11
beacon
MNG
MNG
beacon
beacon
beacon
data
TS 0x00
TS 0x01
TS 0x0f
TS 0x10
TS 0x11
TS 0x1f
repeater
upward
beacon
MNG
MNG
data
TS 0x00
TS 0x01
TS 0x0f
TS 0x10
TS 0x11
TS 0x1f
repeater
downward
beacon
MNG
MNG
data
TS 0x00
TS 0x01
TS 0x0f
TS 0x10
TS 0x11
TS 0x1f
device
beacon
MNG
MNG
data
TS 0x00
TS 0x01
TS 0x0f
TS 0x10
TS 0x11
TS 0x1f

13. Link Management (I) Slot for link management Management frames
downward link
for the coordinator
beacon slot
upward link
bi-directional link for device and coordinator
slot 1
device uses management slot near to the assigned data slot
Management frames
from coordinator
DeviceStatusRepReq, DeviceLinkControl, DeviceLinkInfor
from device
DeviceStatusRep, DeviceLinkInforReq
coordinator
beacon
MNG
MNG
MNG
beacon
MNG
MNG
MNG
beacon
TS 0x00
TS 0x01
TS 0x10
TS 0x11
TS 0x00

14. DeviceStausRepReq (RSSI, LQI)
Link Management (II)
Link power management
reduce interference range
adaptable to radio environmental variance
extend life of near end device
Power control procedure
measure the distance to coordinator
detect radio energy from coordinator
adjust TX power level
reply back to coordinator
feedback from coordinator
coordinator
device
DeviceStausRepReq
measure RSSI, LQI
adjust TX power level
DeviceStausRep
DeviceStausRepReq (RSSI, LQI)
adjust TX power level
DeviceStausRep

15. LECIM MAC Procedure coordinator device Beacon get BO, SO, MO, set WO
estimate next beacon arrival time
i) join to LECIM network
Beacon
adjust clock drift
sleep
Beacon
wakeup at BI*2WO
wait beacon
adjust clock drift
Beacon
DeviceStatusRepReq/ DeivceLinkControl
ii) link management
manage device link infor
DeviceStausRep
sleep
Data
wakeup at device time slot
tx data with grade0 link
wait ACK
ACK
iii) data transmission
Data
wakeup at device time slot
tx data with grade2 link
sleep

16. Thanks for your Attention! ssjoo@etri.re.kr