Considerations on the MAC issue of BAN January 2007 doc.: IEEE 802.15-07-0564 September/2007 Considerations on the MAC issue of BAN Bin Zhen, Huan-bang Li and Ryuji Kohno National Institute of Information and Communications Technology (NICT) Zhen, Li and Kohno Carlos Cordeiro, Philips

Outline IEEE 1073 requirements Comparison of medical SN and general SN January 2007 doc.: IEEE 802.15-07-0564 September/2007 Outline IEEE 1073 requirements Comparison of medical SN and general SN Design principles of MAC Conclusion Zhen, Li and Kohno Carlos Cordeiro, Philips

IEEE 1073 over MBAN HL7 Application presentation Session Transport January 2007 doc.: IEEE 802.15-07-0564 September/2007 IEEE 1073 over MBAN HL7 ISO model Application Medical device data language P1073.1 presentation Device application profile P1073.2.x Session Transport Transport profile Network P1073.3.x Data link MBAN (PHY/MAC) Physical P1073.4.x Zhen, Li and Kohno Carlos Cordeiro, Philips

IEEE 1073 RF wireless group Guidelines chapters January 2007 doc.: IEEE 802.15-07-0564 September/2007 IEEE 1073 RF wireless group Guidelines chapters Wireless medical device use case Technology overview, analysis and constraints Device data characterization QoS requirements Wireless service model Risk management and security Interference and coexistence Conformance and interoperability Medical device data classifications Alarms Waves (real-time and near RT) Parameters (RT and non-RT) Charting (parameters and wave snippet) Control and status History and archival/log Medical device QoS parameters Reliability Latency Priority Bandwidth Data rate Continuous vs. intermittent/burst Zhen, Li and Kohno Carlos Cordeiro, Philips

IEEE 1073 QoS parameters Data type Bandwidth Priority Reliability January 2007 doc.: IEEE 802.15-07-0564 September/2007 IEEE 1073 QoS parameters Data type Bandwidth Priority Reliability Latency Alarm/alert Low (64 bytes), intermittent highest High 3s RT-waves High (120-4000 bps/channel), continuous RT or CS= 3s RT parameters Low-medium, continuous Non-RT parameters Low (20 bytes), intermittent Non-RT events Low-medium, intermittent Medium PoC: 3s, CS: 3s Controls Low, intermittent high PoC: 3s, CS: 5s History/ archive High, burst, intermittent Low Medium high push: 3s, pull: 5s Web browsing 3-5s Zhen, Li and Kohno Carlos Cordeiro, Philips

Analysis of 1073 QoS requirements January 2007 doc.: IEEE 802.15-07-0564 September/2007 Analysis of 1073 QoS requirements Priority and real time Alarm/alert is the top priority We do not have history/archive traffic in BAN Questions Why control is low priority? Is the 3 seconds latency too long? The listed QoS parameters are not suitable for artificial sensing, i.e. cochlear, retina. Zhen, Li and Kohno Carlos Cordeiro, Philips

Medical sensor networks (for BAN) January 2007 doc.: IEEE 802.15-07-0564 September/2007 Comparisons Medical sensor networks (for BAN) General WSN Common features Limited resources: battery, computation, memory, energy efficiency (reception consumes more than transmission) Diversity coexistence environment Dynamic network scale, plug-and-play, low/modest data rate, heterogeneous devices ability, dense distribution Medical sensor/ actuator Single function device (for medical reasons) Multi-function device Lightweight sensors (wearable and implant, space and power limited) Versatile (underwater) sensors Fast relative movement in small range Rare or slow movement in large range device lifetime, days, <10 years network lifetime and device lifetime Months, <10 years Safe (low electromagnetic expose) and quality first (lifetime for implant sensor) Cost sensitive Dependability Reliability (first), guaranteed QoS expected QoS, redundancy-based reliability Strongly security, (except emergency) Required security Zhen, Li and Kohno Carlos Cordeiro, Philips

Medical sensor networks (for BAN) January 2007 doc.: IEEE 802.15-07-0564 September/2007 Comparisons (cont.) Medical sensor networks (for BAN) General WSN Networking Small scale star network (<1e3 nodes) Large scale hierarchical network (<1e6 nodes) no redundancy in device (limited body/interest/effect area) redundant distribution Deterministic node distribution Random node distribution Traffic Periodical RT (dominant), burst (priority) Burst (dominant), periodical Unidirectional traffic Unidirectional and bidirectional traffic Low/modest duty cycle Low duty cycle (typical) M:1 communication M:1 or point-point communication Frequency Specific medical channel (clean, narrow band, licensed by rule) ISM band for part of applications ISM band (narrow/wide band, noise) Channel Body surface or through body Dynamic fading channel (body movement) Obstacle is unknown Zhen, Li and Kohno Carlos Cordeiro, Philips

Star network topology Wearable BAN Bedside BAN January 2007 doc.: IEEE 802.15-07-0564 September/2007 Star network topology headset Blood pressure, temperature, ECG Pacemaker Capsule endoscope Drug deliver Access point Access point Wearable BAN Bedside BAN Zhen, Li and Kohno Carlos Cordeiro, Philips

Star network topology (cont.) January 2007 doc.: IEEE 802.15-07-0564 September/2007 Star network topology (cont.) Single hop network Medical sensors and actuators do not forward message Long distance communication is pushed to coordinator Medical sensor/actuator No redundancy in network distribution Deterministic network position Zhen, Li and Kohno Carlos Cordeiro, Philips

Medical sensor traffic January 2007 doc.: IEEE 802.15-07-0564 September/2007 Medical sensor traffic Periodical traffic Waveform ECG, EEG, EMG, bio-sound, aspiration Image capsule endoscope, neur-stimulation Data Glucose, body temperature, pulse rate, blood lactic acid, expiration, blood pressure, SpO2, joint angle (in ICU, ward and operation room) On-demand traffic Drip infusion, insulin pump Glucose, body temperature, pulse rate, blood lactic acid, expiration, blood pressure, SpO2, joint angle for diagnosis Event-based traffic (alarm) Fall, vital emergency Zhen, Li and Kohno Carlos Cordeiro, Philips

Medical sensor traffic (cont.) January 2007 doc.: IEEE 802.15-07-0564 September/2007 Medical sensor traffic (cont.) Dominant traffics are periodical data Unidirectional data stream Sensing data from medical sensor to coordinator (uplink direction) Command from coordinator to medical actuator (downlink direction) Single function device Zhen, Li and Kohno Carlos Cordeiro, Philips

Requirements from IEEE 1073 January 2007 doc.: IEEE 802.15-07-0564 September/2007 Requirements from IEEE 1073 Scalability Connection sensing blacklist Interrupt from medical sensor to allow service request prior to next schedule polling time Flow control Usually a function in application layer Zhen, Li and Kohno Carlos Cordeiro, Philips

15.4’s drawback for medical applications January 2007 doc.: IEEE 802.15-07-0564 September/2007 15.4’s drawback for medical applications Noisy channel environment No connection sensing Distributed MAC No QoS guarantee Not reliable enough for “life critical data” No interrupt support in beacon-enabled mode Zhen, Li and Kohno Carlos Cordeiro, Philips

Design targets of MBAN Dependable and durable network Constraints January 2007 doc.: IEEE 802.15-07-0564 September/2007 Design targets of MBAN Dependable and durable network Reliability and QoS Lifetime Security and safety Scalability Constraints Limited resources, i.e. memory, computation and battery Noisy and fading channel Coexistence High density of piconets Zhen, Li and Kohno Carlos Cordeiro, Philips

January 2007 doc.: IEEE 802.15-07-0564 September/2007 MAC framework of MBAN Unified MAC mechanism for wearable BAN and implant BAN Traffic classification for QoS Alarm/life critical Real time Best effort Unidirectional data (not forwarded data) Sleep mode to save power Blacklist channel Zhen, Li and Kohno Carlos Cordeiro, Philips

New channel features Not very clear channel model until now January 2007 doc.: IEEE 802.15-07-0564 September/2007 New channel features Not very clear channel model until now Implant channel Strong attenuation Wearable channel Channel scan mechanism Simple energy detection might be not enough Who and how to do it? Zhen, Li and Kohno Carlos Cordeiro, Philips

Traffic classification January 2007 doc.: IEEE 802.15-07-0564 September/2007 Traffic classification Every sensing data must be classified first before transmit Even data from the same source can be classified into different categories. When body temperature is over 40ºC, it is life critical. Otherwise, it is non-life critical Traffic classification in 802.11e is statistic Sensing data MAC mapping Alarm Traffic classifier transmit Real time Best effort Zhen, Li and Kohno Carlos Cordeiro, Philips

Mapping traffic priority to MAC January 2007 doc.: IEEE 802.15-07-0564 September/2007 Mapping traffic priority to MAC ALOHA Higher transmission probability for priority traffic CSMA Fewer backoff step for priority traffic TDMA More allocated time slots for priority traffic (in case of error) FDMA and CDMA seems not to be suitable for BAN Zhen, Li and Kohno Carlos Cordeiro, Philips

January 2007 doc.: IEEE 802.15-07-0564 September/2007 Flow control Typically it is pushed to application layer to simplify PHY/MAC design An MAC interface Radio resource definition Zhen, Li and Kohno Carlos Cordeiro, Philips

Conclusion No redundancy in medical SN Alarm traffic (top priority) January 2007 doc.: IEEE 802.15-07-0564 September/2007 Conclusion No redundancy in medical SN Vital signals are typically position dependent Limited available area Alarm traffic (top priority) Random and priority access Security for alarm transmission Medical traffic pattern Periodical data, on-demand data, and event-driven data Dominant traffics are periodical Unidirectional traffic (no forwarding traffic) New MAC features High reliability for any sensor Unified mechanism for wearable and implantable networks Flow control Zhen, Li and Kohno Carlos Cordeiro, Philips