May 2008 doc IEEE 802 15 15 08

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May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Project: IEEE

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Project: IEEE P 802. 15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [MAC Design Issues and Wake-up Radio for Wireless BANs] Date Submitted: [May, 2008] Source: [Feng Shu and Guido Dolmans] Company: [Holst Centre / IMEC-NL] Address [High Tech Campus 31, Eindhoven, the Netherlands] Voice: [+31 40 2774382], FAX: [+44 40 2746400], E-Mail: [{feng. shu, guido. dolmans}@imec-nl. nl] Abstract: [Presentation for MAC design issues and wake-up radio. ] Purpose: [To discuss MAC design considerations and a wake-up radio for BAN] Notice: This document has been prepared to assist the IEEE P 802. 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 P 802. 15. Submission 1 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 MAC Design

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 MAC Design Issues and Wake-up Radio for Wireless BANs Feng Shu and Guido Dolmans IMEC-NL May, 2008, Jacksonville Submission 2 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Outline •

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Outline • MAC layer design issues p Design challenge: Quality of Service (Qo. S) assurance for heterogeneous applications p Considerations on some design issues such as packet size and reliability • Integrating wake-up radio into BAN sensor nodes Submission 3 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Heterogeneous Traffic

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Heterogeneous Traffic Main traffic types accelerometer p Real-time low rate p Real-time high rate p Command & control p Other small & bulky data video glass MAC design challenge ü Single MAC for co-existent heterogeneous applications ü Meeting very different Qo. S ü Minimizing energy consumption Submission 4 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Qo. S

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Qo. S for BAN Applications: Examples ECG monitoring Video streaming real-time critical real-time non-critical q Periodical data signals q Continuous data flow q Ultra low latency. eg, 50 ms q Moderate latency, eg, ≈500 ms q High reliability, eg, BER 10 -10 q Moderate reliability, eg, BER 10 -4 q Very low data rate, eg, 7. 2 kbps (3 -lead, 200 Hz, 12 bits ADC) q Relatively higher data rate, eg, 2. 8 Mbps (640 x 480) Submission Energy consumption needs to be minimized! 5 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 IEEE 802.

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 IEEE 802. 15. 4 MAC: Pros and Cons Some energy saving features are attractive for BANs: Duty cycling: good trade-off between delay & energy Simplified CSMA-CA: contention-based channel access Reserved medium access: constant bandwidth applications But there are many negatives too … No Qo. S differentiation for multiple types of applications Not adaptive to channel quality variation Not optimized for coexistence of heterogeneous devices No guarantee for life-critical signal transmission Designed without considering human tissue protection Innovative features need to be invented to address MAC requirements for BANs! Submission 6 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Packet Size

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Packet Size • Data are assembled into packets for transmission • It is not trivial to decide optimal packet sizes Short packets deliver small portion of information Long packets decrease efficiency when errored header payload packet • Consider additional issues for packet size in BANs Sampling rate is low for many medical monitoring signals (eg, ECG, 200 Hz, respiration 10 Hz) p Delay requirements are usually strict for medical applications p Submission 7 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Medical Monitoring:

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Medical Monitoring: Examples 10 samples, 12 -bit ADC 5 ms packetization delay Modality Sampling Info bits Delay ECG 200 Hz 120 45 ms Respiration 10 Hz 120 900 ms MAC access, propagation, processing, etc. end-to-end delay Submission 8 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Make Packet

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Make Packet size Variable • Short packet sizes are needed for medical monitoring signals to meet stringent delay requirements • It is not efficient to have short packet sizes for other traffic types such as video streaming, elastic computer data • Make packet size variable in BANs Short packets for delay-sensitive data (eg, medical) Long packets for delay-tolerant data meet delay requirements & improve system efficiency Submission 9 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Reliability l

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Reliability l BAN applications have diversified reliability requirements Medical data usually need higher reliability than non-medical Life-critical medical signals require highest reliability l Trade-off between reliability and efficiency, eg, error control coding high Efficiency app 1 low Submission app 4 app 2 app 3 Reliability Requirement 10 app 5 high Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Differentiating Reliability

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Differentiating Reliability Don’t have to use same strategies for all types of data! high Efficiency app 1 low app 4 app 2 app 3 Reliability Requirement app 5 high Differentiation mechanisms are necessary to address different reliability requirements! Submission 11 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 The Intrinsic

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 The Intrinsic Trade-offs Energy Packet size Throughput BANs Delay Submission Trans. strategies Reliability 12 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Wake-up Radio:

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Wake-up Radio: A Hospital Scenario Patien p t - Wi m EEG p ECG p Resp iration p Sp. O 2 p Perhaps only some sensors are necessary to transmit at a time! p Other sensors are put to sleep, wake up immediately if necessary. Submission 13 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Wake-up Radio

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Wake-up Radio Low power listening might be desirable in BANs • Proposed solution: wake-up radio Stand-by component to watch environment, activate main radio when detecting incoming signals (eg, Pico. Radio) p Extremely low power (e. g. , 50 u. W) p Reduce cost to a minimum Wake-up radio circuitry Sensor node Working toward a low power, low cost wake-up radio with simple signal processing capabilities Submission 14 Shu and Dolmans, IMEC-NL

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Conclusions p

May, 2008 doc. : IEEE 802. 15 -15 -08 -0276 -00 -0006 Conclusions p Identified Qo. S assurance as one of the greatest challenges for MAC design in BANs p Discussed two MAC layer issues: Variable packet sizes Differentiate reliability requirements p Proposed wake-up radio as low-power stand-by mode to prolong life-time of BANs Submission 15 Shu and Dolmans, IMEC-NL