BIOSENSORS: NETWORKS

Terrestrial Sensor Networks:

1. Surface Nodes

   1. Distance: 5km from each other

   2. Communication: Multi-hop method

2. Central-Island Station

   1. Communication: Satellite transmissions

3. Monitoring Station

   1. Communication:

      1. Internet

      2. Satellite transmissions

4. Public

   1. Communication: Internet

Ocean Sensor Networks:

Purposes:

1. Environmental Monitoring

2. Disaster Prevention: Seismic Monitoring, etc.

3. Navigational Assistance

4. Military Assistance

Considerations: Compared to Terrestrial Sensors

1. More expensive

2. Harder to deploy: depends on sensor location

3. Limited power options

4. Greater Memory capacity necessary: channel problems

5. Less data correlation: greater distances

Devices:

1. Two-dimensional UW-ASNs

   1. Location: Ocean Floor

   2. Attachment: Anchored

   3. Purposes:

      1. Tectonic Plate Monitoring

      2. Environmental Monitoring

2. Three-dimensional UW-ASNs

   1. Location: Depth can be varied

   2. Attachment:

      1. Adjustable wire length by electronically controlled motor

      2. Attached to surface buoy with wire

         1. Easy deployment

         2. Depth change with wire length only

         3. Problems:

            • Hard ship navigation

            • Easily deactivated by enemies

      3. Attached to Ocean Floor

         1. Depth change by floating buoy with pump

         2. Hard to attach to floor

         3. Deep ocean

   3. Purposes: Ocean Monitoring

      1. Possibly for Fragile Floor Ecosystems also

      2. Surveying Marine Life

      3. Pollution Monitoring

      4. Bio-geo-chemical processes Monitoring

   4. Challenges:

      1. Collaborating sensors to regulate depth changes to allow surveying of all possible depths

      2. Coordinating depth changes to allow multi-hop relay communication.

3. Three-dimensional networks of AUVs

   1. Location: constituted by vehicles

   2. Attachment: No tethers, cables necessary

   3. Purposes:

      1. Purposes of 2-D UW-ASNs

      2. Purposes of 3-D UW-ASNs

      3. Adaptive Sampling:

         1. If sensor nodes require more data, AUV can come to area.

      4. Self-configuration of sensor network:

         1. AUV can detect holes in network communication

         2. Can serve as node relayer

         3. Can deploy new sensors

   4. Can have multiple sensors attached

Relaying Information:

4. Traditional Approach:

   1. Technique:

      1. Launch sensor

      2. Record data in devices

      3. Recover after monitor time

   2. Problems:

      1. No real time monitoring

         1. Can't access data until retrieval

         2. Environmental problems may occur before then

      2. No adaptability

         1. Can't communicate with the sensors

         2. No changing or reconfiguring the sensors

      3. No monitoring of devices

         1. Failures and/or damages can't be detected until retrieval

         2. May miss important data

      4. Finite storage capacity: Dependent on

         1. Memory

         2. Hard drive space

         3. Battery-life

         4. etc.

5. Wireless Approach

   1. Allows maneuverability

   2. Allows real-time monitoring, despite delays

   3. Prevents loss of data from lines being broken in wired networks

   4. Problems:

      1. Acoustic channels

         1. Temporally and spatially variable

         2. Possible data fading and delay

         3. Limited channels: possible data bottlenecking

         4. High bit error rates

      2. High corrosion rate from water

      3. Prone to failures because of corrosions

Resources:

6. Waves type:

1. Optical:

   1. do not weaken underwater over large distances

   2. Problems:

      1. severe scattering occurs

      2. requires high precision in laser beam direction

2. Radio:

   1. little scattering

   2. Problems: can only travel thru sea water at very low frequencies, i.e. 30 to 300 Hz

7. Power: Limited sources

1. Solar energy

   1. Depths are beyond visible range

2. Batteries

   1. Short life-time

   2. Usually not rechargeable

3. Volcanic energy?

   1. Galapagos not in Ring of Fire

   2. However, is an active Hot Spot.

Communication:

8. Factors Considered

   1. Path loss

      1. Attenuation

      2. Geometric Spreading

   2. Noise

      1. Main-made

      2. Natural

   3. Multi-path propagation

   4. Delays

      1. Intensity

      2. Variance: hard to accurately determine round trip time (RTT)

      3. UW-A channel speed is five orders of magnitude lower than a radio channel's, which causes a large propagation delay (0.67 s/km).

   5. Doppler frequency spread

9. Ocean Floor Nodes

   1. Underwater Sinks (Uss)

      1. Direct Link

         1. Simple

         2. Problem:Large distances

            • High transmission power

            • Not energy efficient

            • Increased acoustic interference

      2. Multi-hop Paths

         1. Relay system

         2. Energy saved

         3. Increased network capacity

         4. Problems: Routing Complexity

            • Needs signaling and computation

10. USs

    1. Two acoustic transceivers

1. Surface station

   1. Vertical acoustic transceivers

   2. Long range for depths up to 10km

2. Ocean Floor Nodes

   1. Horizontal acoustic transceivers

11. Surface station

    1. On-Shore sink (OS) option

       1. Long Range Radio Frequency (RF) Capability

    2. Satellite option

       1. Satellite transmitter

    3. Both require

       1. Long range transceivers

       2. Multiple parallel communications for the USs

12. Monitoring Station

    1. Internet

    2. Satellite

13. Public

    1. Internet

Related Links:

1. Biosensors

   1. Biosensors: Abiotics

   2. Biosensors: Species on Galapagos

   3. Biosensors: Types

   4. Biosensors: Urban Populations

2. Volcanoes

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