doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> July 2008 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [WiseMAC – HA : A Flexible, Scalable, Robust and Ultra Low Power MAC Protocol for Medical BANs] Date Submitted: [10 July, 2008] Source: [Jérôme Rousselot] Company [CSEM SA] Address [Jaquet-Droz 1, CH-2002 Neuchatel, Switzerland] Voice:[0041327205829], FAX: [0041327205720], E-Mail:[jerome.rousselot@csem.ch] Re: [IEEE802.15.6, Original document] Abstract: WiseMAC-HA, a MAC protocol designed specifically for body area networks, is presented and evaluated. Its design guarantees robustness against interferences and node failures, flexibility in network topology, scalability in network size, coexistence with independent networks and an ultra low power consumption. Purpose: [Scalable Medium Access Control protocol for Medical BAN.] 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. Jérôme Rousselot, CSEM <author>, <company>

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> July 2008 WiseMAC – HA A Flexible, Scalable, Robust and Ultra Low Power MAC Protocol for Medical BANs This presentation describes and evaluates CSEM MAC Proposal for Medical Body Area Networks WiseMAC: ULP WSN High Availability: More Robust + Better bandwidth usage Jérôme Rousselot, CSEM <author>, <company>

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> July 2008 Outline Targeted BAN Applications and Requirements Ultra Low Power MAC Protocols The WiseMAC High Availability Protocol Performance Evaluation Conclusion Description of the Applications we are targeting Problems faced by ULP MAC protocols Presentation of our Ultra Low Power Medium Access Control Protocol, efficient with many phy layers Analytical performance evaluation: use case with FM-UWB Conclusion Jérôme Rousselot, CSEM <author>, <company>

Targeted Applications <month year> doc.: IEEE 802.15-<doc#> July 2008 Targeted Applications Medical Body Area Networks Continuous measurements Main Requirements Low Power Scalability Robustness Coexistence Medical Body Area Networks Increased temporal resolution of health parameters Enhanced patient mobility, Better control of drug intake Requirements Ultra Low Power (µW)‏ Low Complexity Portable (Mobility) Robust and Reliable Good Coexistence Transition: There are several ways to organize communications to reduce power consumption [ESENSE 2006] Jérôme Rousselot, CSEM <author>, <company>

Ultra Low Power MAC Design <month year> doc.: IEEE 802.15-<doc#> July 2008 Ultra Low Power MAC Design Types of Energy Waste Idle Listening Signaling Overhead Useless Talking MAC Protocol Families Overhearing Collisions Radio in Rx Mode Radio in Tx Mode ULP MAC Deliver messages reliably and efficiently Means of Action: select radio states Deterministic or Stochastic Compare to IEEE 802.15.4 Beacon: Limited Low Power Mode, Single Point of Failure, No coexistence (signaling traffic collisions) Conclusion: Asynchronous Protocols Scale Better ! Transition: How to communicate asynchronously ? Jérôme Rousselot, CSEM <author>, <company>

Ultra Low Power MAC Design <month year> doc.: IEEE 802.15-<doc#> July 2008 Ultra Low Power MAC Design Types of Energy Waste Idle Listening Signaling Overhead Useless Talking MAC Protocol Families Overhearing Collisions Radio in Rx Mode Radio in Tx Mode No Synchronization ULP MAC Deliver messages reliably and efficiently Means of Action: select radio states Deterministic or Stochastic Compare to IEEE 802.15.4 Beacon: Limited Low Power Mode, Single Point of Failure, No coexistence (signaling traffic collisions) Conclusion: Asynchronous Protocols Scale Better ! Transition: How to communicate asynchronously ? More Scalable Jérôme Rousselot, CSEM <author>, <company>

WiseMAC Ultra Low Power MAC Scheme <month year> doc.: IEEE 802.15-<doc#> July 2008 WiseMAC Ultra Low Power MAC Scheme Periodic Sampling Link-local Synchronization Only WiseMAC Periodic Sampling Asynchronous Sleep Conclusion: Opportunistic Local Synchronization Inefficient Broadcasts Optimizations exist (X-MAC,CSMA- MPS, SyncWUF) but do not bring significant advantages (in steady state)‏ Transition: How well does this scheme perform ? As efficiently as TDMA... WiseNET: an ultralow-power wireless sensor network solution, IEEE Computer, Enz et. al., 2004. WiseMAC: An Ultra Low Power MAC Protocol for Multi-hop Wireless Sensor Networks, El-Hoiydi, Decotignie, AlgoSens 2004. Jérôme Rousselot, CSEM <author>, <company>

WiseMAC Ultra Low Power MAC Scheme <month year> doc.: IEEE 802.15-<doc#> July 2008 WiseMAC Ultra Low Power MAC Scheme Store Forward N = 10 Node Node Node LMAC Crankshaft WiseMAC Deviations from Ideality High Traffic: low cost of wake-up preamble Low Traffic: only the cost of sampling S-MAC SCP-MAC WiseMAC Ideal Store and Forward Scenario Typical traffic scenario in sparse sensor networks Ideal Protocol L-MAC, Crankshaft: Idle Listening S-MAC: Idle Listening + Overhearing SCP-MAC: very optimistic, but still overhearing WiseMAC as good as TDMA schemes Conclusion: WiseMAC close to ideal on a broad range of traffic Transition: What happens in case of interference ? They are an important problem for mobile networks (Texas Instruments CC 2420 radio transceiver) Low Power Medium Access Control Protocols for Wireless Sensor Networks, Jérôme Rousselot, Amre El-Hoiydi and Jean-Dominique Decotignie, European Wireless Conference 2008 (EW 2008), 22-25 June 2008, Prague, Czech Republic. Jérôme Rousselot, CSEM <author>, <company>

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> July 2008 MultiChannel WiseMAC Three Channels What is a channel ? MultiChannel WiseMAC allows autonomous and independent node reconfiguration Detect-and-Avoid + Rediscovery Added benefit: reduced overhearing Conclusion: MultiChannel WiseMAC allows continuity of service at the cost of a temporary performance degradation (increase of latency and power consumption) ‏ Transition: Throughput limitation Jérôme Rousselot, CSEM <author>, <company>

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> July 2008 MultiChannel WiseMAC Advantages Ultra Low Power Robustness to Interference Scalability with network size Flexibility (star and mesh topologies) Low latency Drawbacks Inefficient Broadcasts Limited Throughput Sub-optimal for heterogeneous networks Address WiseMAC limitations by complementing it with an interoperable high throughput protocol TW -> 0 = CSMA Conclusion: Autonomous Mode Change – No Signaling required Transition: How well does it perform ? Have some nodes switch to an interoperable mode that does not exhibit limited throughput = CSMA (IEEE 802.15.4 Non Beacon Enabled Mode)‏ WiseMAC High Availability Jérôme Rousselot, CSEM <author>, <company>

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> July 2008 Power Consumption Sensor Sensor Sensor Sink Sensor Sensor CSMA S-MAC - sink WiseMAC-HA - sensor Ideal - sink S-MAC - sensor Ideal - sensor 5 sensor devices 16 bytes data packets 4 bytes Ack messages FM-UWB (250 kbps)‏ 8 mW Rx 4 mW Tx Sink power consumption higher than sensors because of asymetry CSMA high power consumption acceptable for the sink but not for the sensors. WiseMAC power consumption is close to the optimum, but the protocol is throughput limited. S-MAC power consumption is also throughput limited. Conclusion: WiseMAC-HA allows to trade between energy and throughput at run-time. Transition: What about latency ? WiseMAC Jérôme Rousselot, CSEM <author>, <company>

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> July 2008 Latency Sensor Sensor Sensor Sink Sensor Sensor 100 25 10 5 Traffic limited, not device limited WiseMAC 100 25 10 5 The lines on this figure show an upper bound (95%) on packet latency. WiseMAC-HA is two orders of magnitude more reactive than state of the art ULP protocols. WiseMAC-HA allows much higher throughputs and a more efficient use of bandwidth than ULP protocols. Conclusion: WiseMAC-HA allows to trade between power consumption and latency at run-time. CSMA Jérôme Rousselot, CSEM <author>, <company>

doc.: IEEE 802.15-<doc#> <month year> doc.: IEEE 802.15-<doc#> July 2008 Conclusions WiseMAC-HA Robust and reliable: Detect-and-Avoid interferers Ultra Low Power for all nodes: no need to synchronize Scalable: traffic limited Coexistence: the protocol’s fairness allows simultaneous operation of independent networks Throughput and Latency vs. Energy trade-off Flexibility to decide mode changes Flexibility to accomodate other operating modes Jérôme Rousselot, CSEM <author>, <company>