As no single communication technology is able to satisfy the varied set of requirements usually demanded by the users, a combination of several datalinks is recurrently used to provide the communication service. While the various datalink technologies surveyed present rather different features and capabilities, the COM team focused on the specific set of wanted characteristics that served most to solve the challenges identified. As an example, in the following, we list some of the key wanted features at the datalink level. Dynamic channel selection and frequency hopping to improve reliability in unlicensed spectrum where multiple competing networks may exist.
Both approaches come at the expense of reduced bandwidth. Proper QoS techniques to avoid network congestion while guaranteeing performance for the individual flows generated at the different nodes.
QoS performance highly depends on network topology, and some datalink technologies e. On the other hand, a specific requirement is the ability to transfer the control of robots between different stations operation potentially in different areas, so roaming over different network segments would be required. Having all of the above considerations in mind a detailed comparative study of available solutions was made, resulting in the final selection of the following technologies:.
The latter allows to accommodate different traffic arrival patters latency requirements procuring maximum network utilisation. IEEE The use of such cognitive radio features in disaster response networks offers opportunities to adapt communication links to the various changes in the operating environment and thereby enhance the performance of the communication network [ 26 ].
The combined set of functions will ensure instant interoperability among the variety of unmanned vehicles, personal devices and control stations and will enable performance optimisation by adapting to changing conditions due, for example, to nodes mobility, propagation environment, external interference or evolving mission needs. At IP protocol layer, a single virtual IP network is offered to applications building upon native operating system tools. Rather than providing a single IP to each system platform robot or control station , an IP subnet sized for six different addresses is allocated, so that different physical nodes corresponding the same platform e.
In SAR communications, it is imperative to be able to handle different application flows with different QoS giving priority to certain types of data.promotime.md/wondering-toward-center.php
Search and rescue
In addition to passing data units, applications will use the interface to select applicable QoS parameters, while the COM layer will provide relevant information about connectivity e. In this way, control algorithms can conveniently include communication status information to take better decisions. The set of COM functions briefly introduced in the previous section is implemented in the form of software modules residing in computing nodes associated with the different system entities, namely unmanned vehicles and corresponding control stations, personal devices and mission coordination stations.
The various software modules need to efficiently interface with each other — either within the same or over different platforms nodes — to undertake different control, data or management functions. Two of them APPNODEs represent the main computers aboard a robot and at the RC2 station hosting all the software needed for controlling and supervising the platform and its payload sensors.
In the case of the RC2 station, management and control interfaces are also established between given entities at communication and application levels for overall monitoring and control of mission communications during operations. These parameters refer to three distinct areas:. At radio link level, the controlled parameters are: radio bands and channels frequencies and widths; transmitted power, rate control policy, frame retry policy and waveform mode e.
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Legacy waveforms are eventually used for nodes under particularly disadvantaged radio conditions, for example, located at long distances or in indoor. There are two different toolsets offered to network operators. Operators are provided with a set of utilities for guidance on setting the different configuration parameters. Some of the settings will be subject to dynamic changes during mission execution. At planning phase, the COMCON tool accurately characterises COM components, propagation environments, RF interference and vehicles platforms in order to assess global network performance over wide operation areas; as well as the performance of individual terminals along given mission routes.
Furthermore, the eventual need and location of network relays can be assessed. At operations phase, the COMCON features a centralised monitoring of all key parameters affecting the network performance, allowing to mitigate coverage and throughput problems by timely reconfiguration and eventual reallocation of nodes.
Some optimisation actions of limited impact are performed automatically by the COMMW stacks, while some others of wider scope require human operator intervention to decide the best solution given the current mission conditions. The traffic losses are classified in four different groups:.
External interference, which can be solved by selecting new channels or changing the channel bandwidth. Propagation conditions, which can be solved relocating nodes, moving to basic transmission modes.
Queuing, reflecting packet drops in different system queues, which can be solved limiting application demand. Existing Help us write another book on this subject and reach those readers. Login to your personal dashboard for more detailed statistics on your publications. Our warm environment promotes confidence, creativity and enthusiasm for learning.
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