Projects - User contributions [en]

Projects:2017s1-102 HF Radio Automated Link Establishment (ALE) Model

2017-10-28T07:29:23Z

A1661786:

== Introduction ==
High Frequency (HF) radio communications are able to transmit information such as voice wirelessly over long distances. These distances are achieved by refracting HF waves off layers in the ionosphere. Radio Communications Division of Codan Limited produce a range of HF Radio's which use the 2G-ALE protocol. This project involves tool was made which predicts the call blocking probability for a given system. The tool can also be used to propose a range of channels, for a desired call blocking probability. The ionosphere’s refractive properties vary due to factors such as time of day which in-turn change the channel availablilities of the system. Statistical models were developed to predict a system without ionospheric effects, these were verified on hardware to validate results. The model was then adapted to add probabilities of channels being viable. Online tools are then able to predict the channels viability for a given location and time.

__TOC__

== Background ==
=== High Frequency Radios ===
HF radios communicate at frequency between 3MHz to 30MHz. There are three main propagation modes for HF EM waves, ground waves, tropospheric waves, and sky waves <ref name="one"/>. Ground waves mainly travel short distances <ref name="two"/> while being close to the surface of the earth <ref name="one"/>. Multiple factors such as antenna height, polarisation, frequency and terrain affect attenuation of ground waves <ref name="two"/>. Tropospheric waves are waves that propagate though the troposphere, the lowest part of the atmosphere <ref name="one"/>. The moisture and temperature of the troposphere refracts the waves back to the surface <ref name="one"/>. Sky waves propagate by refracting off the ionosphere, allowing it to travel long distances <ref name="two"/>.

Ions, charged particles such as electrons, can travel freely in the ionosphere before colliding or combining with a neutral particle in the ionosphere due to low pressure air <ref name="three"/>. Because the ionised particles are mainly produced by ultraviolet rays from the sun <ref name="three"/>, the ionospheric properties change at different times of the day <ref name="two"/>. Therefore, different set of frequencies must be used for communication between different stations at different times <ref name="two"/>. Due to the complexity of HF propagation, an operator with HF knowledge were often required to operate HF radios <ref name="four"/>.

=== Automated Link Establishment (ALE) ===
ALE is a standard used in HF radio to automatically initiate a link from one radio to another <ref name="five"/> without any assistance from the radio operator <ref name="four"/>. This standard provides a quick and reliable method for a network of stations to contact each other <ref name="six"/>. There are currently two ALE standards, 2G ALE and 3G ALE, that are in use <ref name="five"/>.

Before ALE was standardised, there were adaptive HF radios <ref name="four"/>. Adaptive HF radios were proprietary solutions for automatic linking between HF radios <ref name="four"/>. Because those solutions were proprietary, HF radios from different manufacturer were not compatible <ref name="four"/><ref name="six"/>. 2G ALE standard was later developed with the cooperation between the United States government and the manufacturers <ref name="four"/> which enabled interoperability of automated link establishment systems for HF radios from different manufacturers <ref name="four"/>. 3G ALE was later introduced which has higher performance while being interoperable with radios with 2G ALE <ref name="six"/>.

All radios with ALE functionality are assigned a callsign <ref name="six"/><ref name="seven"/>. When the radios are idling (i.e. no active link), the radios will constantly scan though a predefined scan list at two to five channels per second <ref name="five"/> to listen for its callsign <ref name="seven"/>. When a call is initiated, the initiator radio will attempt a three-way handshake with the destination radio <ref name="five"/>. The initiator radio chooses the best channel based on data from LQA, a system that measures and stores link quality between radios for different channels in memory <ref name="four"/>, and verifies that it is not in use <ref name="four"/>. The handshake starts with a preamble signal which contains the callsign of the destination radio <ref name="four"/><ref name="six"/>. When the destination radio hears its callsign, the scanning process will be stopped. It then respond to the initiator, indicating that the call was successful <ref name="seven"/>. A final acknowledgement will be sent by the initiator radio to establish the link <ref name="six"/>.

Multiple papers were written to compare 2G ALE and 3G ALE with modelling and simulation. A paper published by Tait et al. <ref name="eight"/> used a range of modelled scenarios compared to 2G ALE and 3G ALE with fast link setup (FLSU). Tait et al. <ref name="eight"/> found that 3G ALE with FLSU performs better in bidirectional networks especially in situations where the ALE network contains many channels. Where lost time was cumulated from linking by the 2G ALE network. However, if the radio network is large, unidirectional, and has a “hub and spoke” topology, 2G ALE and 3G ALE with FLSU have similar performance <ref name="eight"/>. Another paper by Johnson <ref name="nine"/> compared 2G ALE and 3G ALE by simulation. The paper concluded that the simulation demonstrated that 3G ALE has improved network size, SNR requirements, and message throughput over 2G ALE <ref name="nine"/>.

==Conclusion==
Most of the objectives for stage one of the project was achieved. The team was able to develop two models and a software to run the models. However, the team did not manage to fully verify the final model with collected data.
The team developed for a network of fixed radios without propagation effects two models, conditional probability and model with simulation. While the software was being written to house model, data generation scripts was also being written to generate data from physical radios to verify the model.

While data for model generation was being generated, some unexpected behaviour of the radios were observed. The behaviour was further investigated, and multiple hypothesis was proposed on the behaviour.

Although the verification of the model was performed, it was not complete because only one data collection run was performed. Although the simulator could estimate the call connection probability quite well, there was a slight discrepancy between the result from the model and the data from data generation script in estimating the probability of all channels being busy. Therefore, the data verification was not completed. This was mainly due to time restrictions.

==Future Work==
One of the objective for stage one of the project was not fully achieved; the simulator was not verified. The verification of the simulator needs to be performed before moving to the seconds and the third stage of the project. More test needs to be performed on the simulator for it to be verified.

The next stage of the project is to process with stage two and stage three of the project. This stage of the project is to implement ionospheric propagation effects to the to the model. VOACAP software could be used to predict the ionosphere which can assist in predicting the blocking probability of channels.

== Project Team ==
* Supervisors
** Langford White
** Paul Hirschausen
*Students
** Xuyang Jie
** Andrew Thornton
** Chung Seng Foong

==References==
<references>
<ref name="one">J. S. Seybold, [https://books.google.com.au/books?id=4LtmjGNwOPIC&lpg=PP1&pg=PA6#v=onepage&q&f=false Introduction to RF Propagation], John Wiley & Sons, 2005.</ref>
<ref name="two">“[http://www.sws.bom.gov.au/Category/Educational/Other%20Topics/Radio%20Communication/Intro%20to%20HF%20Radio.pdf Introduction to HF Radio Propagation],” [Online]. [Accessed 1 April 2017].</ref>
<ref name="three">D. J. Lusis, “[https://www.arrl.org/files/file/Technology/tis/info/pdf/8312011.pdf HF Propagation: The Basics],” QST, pp. 11-15, 1983.</ref>
<ref name="four">R. E. Menold, “[https://www.arrl.org/files/file/Technology/tis/info/pdf/9502068.pdf ALE-THE COMING OF AUTOMATIC LINK ESTABLISHMENT],” QST, vol. 79, no. 2, pp. 1-3, 1995. </ref>
<ref name="five">“[http://hflink.com/standards/ALE_standard_188_141B.pdf Interoperability and performance standard for medium and high frequency radio systems],” 1 March 1999. [Online]. [Accessed 20 March 2017].</ref>
<ref name="six">“[http://hflink.com/itu/ITU_ALE_Handbook.pdf Frequency-adaptive communication systems and networks in MF/HF],” 2002. [Online]. Available: . [Accessed 3 April 2017].</ref>
<ref name="seven">“[http://hflink.com/automaticlinkestablishment/ Automatic Link Establishment],” HF-LINK, [Online]. [Accessed 21 April 2017].</ref>
<ref name="eight">D. Tait, A. Gillespie and S. Trinder, “[http://ieeexplore.ieee.org/document/6251376/ MODELLING 2G AND 3G ALE: A QUANTITATIVE COMPARISON],” in 12th IET International Conference on Ionospheric Radio Systems and Techniques (IRST 2012), York, 2012. </ref>
<ref name="nine">E. E. Johnson, “[http://ieeexplore.ieee.org/document/821350/ Simulation results for third-generation HF automatic link establishment],” in IEEE Military Communications. Conference Proceedings, Alantic City, 1999. </ref>
</references>

Projects:2017s1-102 HF Radio Automated Link Establishment (ALE) Model

2017-09-21T14:35:04Z

A1661786: /* High Frequency radio communications */

__TOC__
= Introduction =
High Frequency (HF) radio communications are able to transmit information such as voice wirelessly over long distances. These distances are achieved by refracting HF waves off layers in the ionosphere. The Radio Division of Codan limited produce a range of HF Radio's which use the 2G-ALE protocol. A tool was made which predicts the call blocking probability for a given system. The tool can also be used to propose a range of channels, for a desired call blocking probability. The ionosphere’s refractive properties vary due to factors such as time of day which in-turn change the channel availabilities of the system. Statistical models were developed to predict a system without ionospheric effects, these were verified on hardware to validate results. The model was then adapted to add probabilities of channels being viable. Online tools are then able to predict the channels viability for a given location and time.

== Background ==
=== High Frequency Radio Communications ===
HF radio communications uses 3MHz to 30MHz electromagnetic waves to transmit information such as voice wirelessly over long distances. The waves emit from the antenna will either be absorbed or refracted by the ionosphere layers, allowing the waves to travel several hundred kilometres. The refracted waves will travel to the destination radio station while the absorbed waves will vanish in space. The layers include innermost layer (D layer), middle layer (E layer), Appleton–Barnett layer (F1,F2 layer).

=== Automated Link Establishment (ALE) ===
ALE is a standard used in HF radio communications to initiate link from one station to another. This standard is used to provide a quick and reliable method for a network of stations to contact each other. The system automatically selects a channel based on the data collected from previous links and external data to achieve higher quality links. Station with receivers will also scan through a list of channels for calls.

= Project Team =
* Supervisors
** Langford White
** Paul Hirschausen
*Students
** Xuyang Jie
** Andrew Thornton
** Chung Seng Foong

Projects:2017s1-102 HF Radio Automated Link Establishment (ALE) Model

2017-09-21T14:25:41Z

A1661786: /* Background */

__TOC__
= Introduction =
High Frequency (HF) radio communications are able to transmit information such as voice wirelessly over long distances. These distances are achieved by refracting HF waves off layers in the ionosphere. The Radio Division of Codan limited produce a range of HF Radio's which use the 2G-ALE protocol. A tool was made which predicts the call blocking probability for a given system. The tool can also be used to propose a range of channels, for a desired call blocking probability. The ionosphere’s refractive properties vary due to factors such as time of day which in-turn change the channel availabilities of the system. Statistical models were developed to predict a system without ionospheric effects, these were verified on hardware to validate results. The model was then adapted to add probabilities of channels being viable. Online tools are then able to predict the channels viability for a given location and time.

== Background ==
=== High Frequency radio communications ===
HF radio communications uses 3MHz to 30MHz electromagnetic waves to transmit information such as voice wirelessly over long distances. The waves emit from the antenna will either be absorbed or refracted by the ionosphere layers, allowing the waves to travel several hundred kilometres. The refracted waves will travel to the destination radio station while the absorbed waves will vanish in space. The layers include innermost layer (D layer), middle layer (E layer), Appleton–Barnett layer (F1,F2 layer).

=== Automated Link Establishment (ALE) ===
ALE is a standard used in HF radio communications to initiate link from one station to another. This standard is used to provide a quick and reliable method for a network of stations to contact each other. The system automatically selects a channel based on the data collected from previous links and external data to achieve higher quality links. Station with receivers will also scan through a list of channels for calls.

= Project Team =
* Supervisors
** Langford White
** Paul Hirschausen
*Students
** Xuyang Jie
** Andrew Thornton
** Chung Seng Foong

Projects:2017s1-102 HF Radio Automated Link Establishment (ALE) Model

2017-09-21T14:24:16Z

A1661786:

__TOC__
= Introduction =
High Frequency (HF) radio communications are able to transmit information such as voice wirelessly over long distances. These distances are achieved by refracting HF waves off layers in the ionosphere. The Radio Division of Codan limited produce a range of HF Radio's which use the 2G-ALE protocol. A tool was made which predicts the call blocking probability for a given system. The tool can also be used to propose a range of channels, for a desired call blocking probability. The ionosphere’s refractive properties vary due to factors such as time of day which in-turn change the channel availabilities of the system. Statistical models were developed to predict a system without ionospheric effects, these were verified on hardware to validate results. The model was then adapted to add probabilities of channels being viable. Online tools are then able to predict the channels viability for a given location and time.

== Background ==
HF radio communications, using 3MHz to 30MHz electromagnetic waves, can transmit information such as voice wirelessly over long distances. The waves emit from the antenna will either be absorbed or refracted by the ionosphere layers, allowing the waves to travel several hundred kilometres. The refracted waves will travel to the destination radio station while the absorbed waves will vanish in space. The layers include innermost layer (D layer), middle layer (E layer), Appleton–Barnett layer (F1,F2 layer).

ALE is a standard used in HF radio communications to initiate link from one station to another. This standard is used to provide a quick and reliable method for a network of stations to contact each other. The system automatically selects a channel based on the data collected from previous links and external data to achieve higher quality links. Station with receivers will also scan through a list of channels for calls.

= Project Team =
* Supervisors
** Langford White
** Paul Hirschausen
*Students
** Xuyang Jie
** Andrew Thornton
** Chung Seng Foong

Projects:2017s1-102 HF Radio Automated Link Establishment (ALE) Model

2017-09-21T14:20:45Z

A1661786:

__TOC__
= Introduction =
High Frequency (HF) radio communications are able to transmit information such as voice wirelessly over long distances. These distances are achieved by refracting HF waves off layers in the ionosphere. The Radio Division of Codan limited produce a range of HF Radio's which use the 2G-ALE protocol. A tool was made which predicts the call blocking probability for a given system. The tool can also be used to propose a range of channels, for a desired call blocking probability. The ionosphere’s refractive properties vary due to factors such as time of day which in-turn change the channel availabilities of the system. Statistical models were developed to predict a system without ionospheric effects, these were verified on hardware to validate results. The model was then adapted to add probabilities of channels being viable. Online tools are then able to predict the channels viability for a given location and time.

== Background ==
High Frequency (HF) radio communications, using 3MHz to 30MHz electromagnetic waves, can transmit information such as voice wirelessly over long distances. The waves emit from the antenna will either be absorbed or refracted by the ionosphere layers. The refracted waves will travel to the dest radio station while the absorbed waves will vanish in space. The layers include innermost layer (D layer), middle layer (E layer), Appleton–Barnett layer (F1,F2 layer).

= Project Team =
* Supervisors
** Langford White
** Paul Hirschausen
*Students
** Xuyang Jie
** Andrew Thornton
** Chung Seng Foong

Projects:2017s1-102 HF Radio Automated Link Establishment (ALE) Model

2017-09-21T14:19:30Z

A1661786: Created page with "= Introduction = High Frequency (HF) radio communications are able to transmit information such as voice wirelessly over long distances. These distances are achieved by refrac..."

= Introduction =
High Frequency (HF) radio communications are able to transmit information such as voice wirelessly over long distances. These distances are achieved by refracting HF waves off layers in the ionosphere. The Radio Division of Codan limited produce a range of HF Radio's which use the 2G-ALE protocol. A tool was made which predicts the call blocking probability for a given system. The tool can also be used to propose a range of channels, for a desired call blocking probability. The ionosphere’s refractive properties vary due to factors such as time of day which in-turn change the channel availabilities of the system. Statistical models were developed to predict a system without ionospheric effects, these were verified on hardware to validate results. The model was then adapted to add probabilities of channels being viable. Online tools are then able to predict the channels viability for a given location and time.

== Background ==
High Frequency (HF) radio communications, using 3MHz to 30MHz electromagnetic waves, can transmit information such as voice wirelessly over long distances. The waves emit from the antenna will either be absorbed or refracted by the ionosphere layers. The refracted waves will travel to the dest radio station while the absorbed waves will vanish in space. The layers include innermost layer (D layer), middle layer (E layer), Appleton–Barnett layer (F1,F2 layer).

= Project Team =
* Supervisors
** Langford White
** Paul Hirschausen
*Students
** Xuyang Jie
** Andrew Thornton
** Chung Seng Foong