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Concept
Dynamic spectrum management
Résumé
Dynamic spectrum management (DSM), also referred to as dynamic spectrum access (DSA), is a set of techniques based on theoretical concepts in network information theory and game theory that is being researched and developed to improve the performance of a communication network as a whole. The concept of DSM also draws principles from the fields of cross-layer optimization, artificial intelligence, machine learning etc. It has been recently made possible by the availability of software radio due to development of fast enough processors both at servers and at terminals. These are techniques for cooperative optimization. This can also be compared or related to optimization of one link in the network on the account of losing performance on many links negatively affected by this single optimization.
It is most commonly applied to optimize digital subscriber line (DSL) performance of a network. Another potential application of DSM is for cognitive radio.
Important and common principles of DSM include:
Link adaptation
Bandwidth management
Multi-user MIMO
Pre-cancellation of estimated interference
Combining unused channels (not pre-allocated) for a single user or bonding
DSM can be achieved over ordinary copper phone lines' network by reducing or eliminating crosstalk, interference and near–far problem within a DSL network especially affecting the DSL phone lines that are close together in a binder.
The technique involves multiple methods:
Continuously monitoring the status of interfering signal levels using current bit-loading compared to maximum achievable bit rate, number of errored seconds, number of severely errored seconds, number of forward error corrections (FEC) and making decisions about the underperforming scenario's cause and forcing the link to train in a specific way.
Identifying the neighborhood cables in the binders that may be causing unwanted cross-talk and lowering their upstream transmission power until bit-rates are optimized for the network.
Source officielle
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