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Improving Wireless Health Monitoring Using Incentive-Based Router Cooperation

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Title: Improving Wireless Health Monitoring Using Incentive-Based Router Cooperation


1
Improving Wireless Health Monitoring Using
Incentive-Based Router Cooperation
  • Upkar Varshney, Georgia State University
  • ?????

2
Outline
  • 1. Introduction
  • 2. Incentive-based router cooperation
  • 3. Analytical model
  • 4. Performance evaluation
  • 5. Conclusion

3
1. Introduction(1/5)
  • In recent years, researchers have explored the
  • requirements and potential benefits of
    wireless
  • networks in health monitoring.
  • One of the most difficult challenges associated
    with
  • using wireless networks is the
    reliability of message
  • delivery.
  • End-to-end delays, frequency, and the number of
  • patients also affect the quality of
    monitoring.

4
1. Introduction(2/5)
  • Many healthcare providers are beginning to use
    infrastructure-oriented wireless networks such as
    IEEE 802.11 wireless LANs and cellular systems to
    monitor and track Patients.
  • The infrastructure supports monitoring devices in
    hospitals and nursing homes, outdoors, and at
    home using base stations (cellular networks) or
    access points (wireless LANs).

5
1. Introduction(3/5)
  • However, potentially spotty coverage due to time-
    and location-dependent channel quality and signal
    attenuation resulting in dead spots can
    significantly diminish message delivery
    reliability.

6
1. Introduction(4/5)
  • Healthcare providers could use ad hoc networks to
    supplement the sometimes spotty and unreliable
    coverage of infrastructure-oriented wireless
    networks for patient monitoring.
  • A proposed incentive-based approach encourages
    devices to cooperate as routers, significantly
    improving message delivery reliability.

7
1. Introduction(5/5)
8
2. Incentive-based router cooperation(1/9)
  • Potential message delivery problems due to
    uncooperative routers can be overcome by
  • Implementing persistent transmission, which lets
    uncooperative devices transmit at reduced power
    levels at reduced distances.
  • Using more persistent multi-path routing schemes
    such as reliable multicast and reliable
    broadcast.
  • Excluding uncooperative devices from the routes
    as in a multicast tree.

9
2. Incentive-based router cooperation(2/9)
  • Perhaps the best way to obtain router cooperation
    is to offer a range of incentives from credits to
    higher-priority message delivery.
  • Devices could decide whether to cooperate based
    on offered or earned incentives.
  • Messages could be forwarded based on a devices
    history of cooperation.
  • Devices that have been cooperative in the past
    would be given higher message-delivery priority,
    while those that have been uncooperative would be
    given lower priority.
  • Higher incentives could also be assigned to
    certain types of messages, such as emergency
    alerts, to encourage their delivery.

10
2. Incentive-based router cooperation(3/9)
  • Vital credits
  • NTnetwork traffic load, depends on the number of
    monitored patients,
  • frequency of monitoring, packets per
    monitored event, and routing
  • scheme.
  • Pmessage priority level
  • Ccriticality of the routing device, as
    determined by its position in the
  • network and the current routing scheme.
  • L and M and Nconstants that can be chosen to
    emphasize certain factors
  • in Vital credits
    that allow the modeling of different
  • environments.

11
2. Incentive-based router cooperation(4/9)
12
2. Incentive-based router cooperation(5/9)
13
2. Incentive-based router cooperation(6/9)
  • Cooperation Protocol
  • Depending on the devices complexity and desired
    accuracy in decision making
  • Continuous Value Cooperation Protocol (CVCP).
  • Discrete Value Cooperation Protocol (DVCP).
  • CVCP
  • Larger ad hoc networks
  • By keeping all parameters and computations at
    exact values
  • Relatively accurate decision making
  • More computation and storage overhead
  • Suited to devices with complex functionalities

14
2. Incentive-based router cooperation(7/9)
  • The health-monitoring devices running CVCP are
    likely to be more powerful and have functionality
    for power conservation.
  • The devices can choose the values of constants A
    (stored credits) and B (available power) based on
    desired thresholds.

15
2. Incentive-based router cooperation(8/9)
  • DVCP
  • Smaller ad hoc networks
  • Approximate values such as high (H), medium (M),
    and low (L)
  • Simplifies computations
  • Less overhead
  • Less accurate decision making
  • Simpler health-monitoring devices
  • Not support sleep-cycle-based power conservation

16
2. Incentive-based router cooperation(9/9)
  • For smaller incentive values at low network loads
    ,CVCP and DVCP performance should not differ
    greatly.
  • CVCP is likely to achieve decision-making
    accuracy superior to DVCP in larger, more complex
    ad hoc networks.
  • In general, for both CVCP and DVCP, the use of
    Vital credits should improve health-monitoring
    reliability.

17
3. Analytical model(1/8)
  • Author developed an analytical model to assess
    the effectiveness of Vital-credits-based router
    cooperation in terms of message reliability under
    varying network load and size.
  • To maintain tractability and reasonable accuracy,
    this model assumes
  • The path between patient and healthcare
    professional is a pure multihop ad hoc network
  • All devices have the same power budget and
    processing power
  • The devices are uniformly distributed in the
    service area

18
3. Analytical model(2/8)
19
3. Analytical model(3/8)
  • The probability of finding a path to a
    destination user is a joint probability of
    finding a minimum number of devices needed to
    form a path between a patient and a healthcare
    professional.
  • Next-hop device probability
  • UENext-hop device probability
  • DEThe device distribution function (higher for
    uniformly low for cluster)
  • NEThe number of cooperating devices
  • CEThe device coverage
  • ALength of service area
  • BWidth of service area

20
3. Analytical model(4/8)
  • UE-UN UE ( 1 PUN )
  • UEUNNext-hop device probability with
    noncooperation
  • PUNThe probability of encountering an
    uncooperative
  • device
  • ISTStored incentives
  • IOFFOffered incentives
  • L and MBe used to change the relative
    importance of
  • stored and offered Vital
    credits
  • FA factor used to normalize the probability to
    (0, 1) range

21
3. Analytical model(5/8)
  • Message delivery reliability can be measured in
    terms of the probability of message reception.
  • Unicasttransmitting messages to a single
  • healthcare professional
  • RU Reliability of message delivery using
    unicast
  • routing
  • H The number of hops to the destination

22
3. Analytical model(6/8)
  • Anycasttransmitting messages to at least one
  • healthcare professional
  • RA Reliability of message delivery using
    anycast routing
  • DN The number of healthcare professionals
    doing the
  • monitoring

23
3. Analytical model(7/8)
  • Multicastusing multiple paths to deliver
  • messages
  • RMReliability of message delivery using
    multicast
  • routing
  • MThe number of paths used

24
3. Analytical model(8/8)
  • Broadcastusing every possible device to deliver
    messages
  • RBReliability of message delivery using
    broadcast routing
  • PBThe probability of finding a broadcast path to
    a definition
  • PPThe number of paths between a patient and a
  • professional

25
4. Performance evaluation(1/2)
  • Assumed
  • 3 healthcare professionals
  • 18 devices
  • The initial stored incentives were equal
  • Offered incentives were based on network traffic
    and packet priority
  • Device criticality was fixed at 1
  • 9 for multicast routing
  • 45 for broadcast routing.

26
4. Performance evaluation(2/2)
27
5. Conclusion(1/1)
  • Ad hoc networks could be used to supplement the
    sometimes spotty and unreliable coverage of
    infrastructure-oriented wireless networks for
    health monitoring.
  • The performance results from analytical model
    show that using incentives such as Vital credits
    can significantly improve message delivery
    reliability.
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