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HF Multi-hop Network for Emergency Communication

HF Multi-hop Network for Emergency Communication. There are Maximum Useful Frequency (MUF) and lower Absorption Frequency (ALF) bounds for communication between tow terminals. HF communication is dependent on: 1- Frequency 2- Range or path length 3- Antenna elevation angle

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HF Multi-hop Network for Emergency Communication

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  1. HF Multi-hop Network for Emergency Communication There are Maximum Useful Frequency (MUF) and lower Absorption Frequency (ALF) bounds for communication between tow terminals. HF communication is dependent on: 1- Frequency 2- Range or path length 3- Antenna elevation angle 4- Height of the ionosphere 5- density of ionization of the layer skip zone: Region between maximum ground-wave distance(30~50km) and closest point where HF are returned from the ionosphere.

  2. f0 f h D Important frequency Critical frequency : = the maximum electron density in a given ionized layer Maximum Usable Frequency (MUF) : D= the distance between the station h= height of the reflection point Optimal work Frequency (OWF) :

  3. E & F1 at daytime The Relationship between angle and frequency F1 layer at 12:00 E layer at 12:00

  4. E & F1 at daytime The Relationship between frequency and distance E layer at 12.00 F1 layer at 12.00

  5. F at night F at 22.00 Frequency and distance Angle and frequency

  6. Using the antenna positioned in Honnjo campus Receive the internationally broadcasted radio in HF band. Experiment

  7. Experiment Equipments T2FD antenna DSP Receiver NRD-545 (T2FD): Terminated Tilted Folded Dipole

  8. Sample of Experiment results

  9. HF multi hop Network • Communication for long distance 　　→HF wave • Communicate with neighbor station 　　→Ground wave • Skip zone correspondence 　　→multi hop • Merger between HF wave and ground wave We analyze the model when data packet is transmitted using direct broadcasting. The packet will be forwarded by HF multi hop in same frequency that have been received. The purpose of our proposal system To assure the data we transmitted can be received by all stations

  10.  Situation1：Recover the connection F • When the frequencies been changed, the distances will also been changed. Therefore the network can be newly construct. E A B

  11. Situation2：skip zone access F E A D B Ground wave C In said A station skip zone Stations in the skip zone can be reached by successfully usage of theGround wave and reflection on the ionosphere by HF band.

  12. Experiment (1.2) HF coverage distance : Experiment detail: Stations: 1-fixed 2-moving (by car) Elevation angle:height elevation angle Frequency:low frequency Expected result: The distance of HFcoverage area and signal strength

  13. Simulation results 2

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