doc.: IEEE 802.15-09-0336-00-0006

Submission

<May 2009>

<J.S.Yoon>, <CUNY>Slide 1

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Submission Title: [Versatile MAC for Body Area Network ]Date Submitted: [4 May, 2009]Source: [J.S Yoon, Gahng S. Ahn, Myung J Lee, Seong-soon Joo] Company [CUNY, ETRI]Address [140th St. and Convent Ave, New York, NY, USA ]Voice:[+1-212-650-7180], FAX: [], E-Mail:[jsyoon@ee.ccny.cuny.edu, gahn@ccny.cuny.edu, lee@ccny.cuny.edu , ssjoo@etri.re.kr]

Re: [Versatile MAC for BAN proposal responding to TG6 Call for Proposals (15-08-0811-03-0006-tg6- call-proposals) ]

Abstract: [This document describes a Versatile MAC that is being proposed to the TG6 group ]

Purpose: [Discussion in 802.15.6 Task Group ]

Notice: This document has been prepared to assist the IEEE P802.15. 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 P802.15.

doc.: IEEE 802.15-09-0336-00-0006

Submission

Versatile MAC for Body Area Networks

June S Yoon, Gahng S Ahn, Myung J Lee, Seong S. Joo

CUNY, ETRI

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 2

doc.: IEEE 802.15-09-0336-00-0006

Submission

Outline• Motivation • Challenges• BAN MAC

– Overview

– Details of each period• AD, CAP, Beacon, DTS, ETS, CAP Extension

– Energy saving

– Prioritization

• Performance• Summary

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 3

doc.: IEEE 802.15-09-0336-00-0006

Submission

Motivation

To design a simple MAC protocol

to support various QoS for

Body Area Networks

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 4

doc.: IEEE 802.15-09-0336-00-0006

Submission

Design Challenges • QoS Assurance

– High reliability and guaranteed latency requirement for real time data, especially vital data

Need deterministic structure

• Flexibility– Support various types (periodic, non-periodic, medical,

entertainment…) of traffic, data rate and PHYs

Instantly adaptable to application’s requirements

• Energy efficiency– Less energy consumption especially for implanted device

Need efficient active/inactive scheduling<J.S.Yoon>, <CUNY>

<May 2009>

Slide 5

doc.: IEEE 802.15-09-0336-00-0006

Submission

Proposed BAN MAC Features

• Versatile MAC– Best breed of Contention based and TDMA

– Supports various (burst, periodic, continuous) types of traffic

• Straightway reservation (Ad-CAP-Beacon)– Fast reservation and prompt adaption

– Latency reduction for delay sensitive real time data

• Emergency data transmit slot– Highly adaptable to abrupt emergency data

– Support high QoS and reliability

• Priority supported

• Low energy consumption

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 6

doc.: IEEE 802.15-09-0336-00-0006

Submission

Versatile MAC Overviews

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 7

doc.: IEEE 802.15-09-0336-00-0006

Submission

BSF (BAN Superframe)

• Ad (Advertisement)– Synch, interval, address

• CAP– Reservation, Non-periodic data

• Beacon– Synch, reservation status announcement

• DTP (Data Transmit Period)– DTS (Data Transmit Slot)

• Periodic data transmit by reservation

– ETS (Emergency Data Transmit Slot)• Periodic data & Emergency data

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 8

doc.: IEEE 802.15-09-0336-00-0006

Submission

Details of each period

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 9

doc.: IEEE 802.15-09-0336-00-0006

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Advertisement

• The beginning of BSF (BAN Superframe) followed by contention access period

• Ban Coordinator (BC) broadcasts it at the beginning of BSF and contains basic information such as– Synchronization– BC (Ban Coordinator) address– Ad Interval, length of periods

• A newly joined node adjusts its clock, gets information on BC and BSF

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 10

doc.: IEEE 802.15-09-0336-00-0006

Submission

CAP

• Contention access period– Backoff and carrier sense to avoid collision

– Prioritized back-off and carrier sense to serve higher priority first

• Data Transmission– Command frames for DTS reservation exchanged

– Non-periodic data including alarm and periodic data failed to reserve DTS can be sent

• BC collects all the DTS requests and allocate them according to their priorities and slot availability– Allocate first available slot based on the priority order to prevent

DTS shortage

– Lower priority slots may be preempted by higher priority data

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 11

doc.: IEEE 802.15-09-0336-00-0006

Submission

Beacon

• BC Broadcasts beacon before DTP– Notifies sync, interval, length, DTS reservation status

• All the nodes that reserved DTS should listen beacon every AI to check reservation status changes

• Sequential Ad-CAP-Beacon enables straightway slot reservation and prompt accommodation to changes

<J.S.Yoon>, <CUNY>Slide 12

doc.: IEEE 802.15-09-0336-00-0006

Submission

Comparison: Reservation delay (From data generation to slot assign confirm by beacon)

• Proposed approach– Min: 1 slot (7.68ms)

• Data generation at the end of CAP

– Max: 129 slots (0.991s)• Data generation at the beginning of beacon• Beacon (1)+ AI (128)

• 15.4 based approach– Min: 120 slots (0.922s)

• Data generation at the end of CAP • CFP & Inactive(119) + Beacon(1)

– Max: 248 slots (1.905s)• Data generation at the beginning of CFP• CFP & Inactive(119) + BI(128) + Beacon(1)

Difference = 119 slot, 0.91s

Assume slot size and AI, BI are same (BO=6, SO=3, 128 slots) & reservation is done right away if data is generated during CAP

<J.S.Yoon>, <CUNY>Slide 13

doc.: IEEE 802.15-09-0336-00-0006

Submission

Data Transmit Period

• TDMA Period for the latency-critical continuous and periodic data

• DTS (Data Transmit Slot)

– Nodes transmit data at the slot assigned by BC

• ETS (Emergency Data Transmit slot)

– Contention access period– If any, emergency data is transmitted at this slot– A node assigned to this slot performs carrier sense first so as to

prevent collision with emergency alarm– Enables urgent transmission for abrupt Emergency alarm

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 14

doc.: IEEE 802.15-09-0336-00-0006

Submission

Comparison: Alarm delay (From alarm generation to transmit)

Assume slot size and AI, BI(15.4) are same (BO=6, SO=3, 128 slots) andAll CFP and DTP are occupied

• Alarm delay decreases as the number of ETS slot increases, however, at the expense of increased delay (carrier sense time) of the ETS slot owners.

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 15

doc.: IEEE 802.15-09-0336-00-0006

Submission

Options

• ECAP (CAP Extension)– The duration between the ends of DTP and AI– If power is not a concern for BC, it can stay awake and maintain

CAP – All kinds of data can be transmitted including retransmission

• Batch ACK– Ack at the last active slot for all data transmission in DTP

• Delayed ACK– Ack for multiple-slot transmission from a same source

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 16

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Submission

Prioritization

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 17

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Submission

BAN Data Prioritization

• Prioritization based on QoS (latency) requirement

– Priority 0: Emergency reaction alarm • Emergency vital signs, Battery depletion, ...

– Priority 1: Medical Continuous data• Latency critical data

– E.g. EEG/ECG/EMG

– Priority 2: Medical Routine data• Reliability critical but lesser latency requirement

– E.g. Temperature, blood pressure

– Priority 3 : Non-medical Continuous data• Video, audio

– Priority 4 : Others Priority classes are dictated by the applications

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 18

doc.: IEEE 802.15-09-0336-00-0006

Submission

Prioritized Transmit in DTP• Priority based allocation

– Higher priority data served first in case of contention among different priority traffics

• Emergency data transmission in ETS– Owner of the slot performs carrier sense before

transmission

– Alarms perform short random backoff and carrier sensewinner takes the slot, loser try again at the next ETS or CAP• T(Backoff+Carrier sense+TxAlarm) < T(Carrier senseOwner)

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 19

doc.: IEEE 802.15-09-0336-00-0006

Submission

Prioritized Transmit in CAP• Higher priority data access channel first

•  Prioritized back-off– Prioritized Back-off exponent = Min. Back-off exponent-1– Constant– Raises the probability that emergency alarm takes less back-

off duration than others.

• Prioritized carrier sense– Prioritized Carrier sense duration = Carrier sense duration x0.5

– Situation that normal and prioritized back-off starts at the same time with same duration, emergency alarm can captures channel first.

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 20

doc.: IEEE 802.15-09-0336-00-0006

Submission

Energy Saving• Coordinator

– Goes into inactive If no activity is scheduled after CAP or DTP

• Sensor (continuous data)– Once DTS reservation is done, the node stay inactive period

except for beacon and its reserved transmit time

• Sensor (routine data)– Wakeup only for report and transmit during CAP or CAP

Extension whichever available first

• Sensor (Alarm)– Wakeup only for report and transmit during CAP, CAP

Extension or ETS whichever available first

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 21

doc.: IEEE 802.15-09-0336-00-0006

Submission

Summary of BAN MAC

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 22

doc.: IEEE 802.15-09-0336-00-0006

Submission

Summary

• Versatile MAC– CAP: Contention period

– DTP: TDMA period, Enables high QoS

• Straightway reservation – Fast reservation, adaptation

– Latency reduction

• Emergency data transmit slot– Highly adaptable to abrupt emergency data

– Support high QoS and reliability

• Priority supported

<J.S.Yoon>, <CUNY>

<May 2009>

Slide 23