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

Information theory

Information theory is a branch of applied mathematics and electrical engineering involving the quantification of information. Information theory was developed by Claude E. Shannon to find fundamental limits on signal processing operations such as compressing data and on reliably storing and...

 and game theory

Game theory

Game theory is a mathematical method for analyzing calculated circumstances, such as in games, where a person’s success is based upon the choices of others...

 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

Cross-layer optimization

Cross-layer optimization is an escape from the pure waterfall-like concept of the OSI communications model with virtually strict boundaries between layers. The cross layer approach transports feedback dynamically via the layer boundaries to enable the compensation for e.g...

, artificial intelligence

Artificial intelligence

Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...

, machine learning

Machine learning

Machine learning, a branch of artificial intelligence, is a scientific discipline concerned with the design and development of algorithms that allow computers to evolve behaviors based on empirical data, such as from sensor data or databases...

 etc. It has been recently made possible by the availability of software radio

Software-defined radio

A software-defined radio system, or SDR, is a radio communication system where components that have been typically implemented in hardware are instead implemented by means of software on a personal computer or embedded computing devices...

 due to development of fast enough processors both at servers and at terminals. These are techniques for cooperative

Cooperation

Cooperation or co-operation is the process of working or acting together. In its simplest form it involves things working in harmony, side by side, while in its more complicated forms, it can involve something as complex as the inner workings of a human being or even the social patterns of a...

 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

Digital Subscriber Line

Digital subscriber line is a family of technologies that provides digital data transmission over the wires of a local telephone network. DSL originally stood for digital subscriber loop. In telecommunications marketing, the term DSL is widely understood to mean Asymmetric Digital Subscriber Line ,...

 (DSL

ITU G.992.1

In telecommunications, ITU G.992.1 is an ITU standard for ADSL using discrete multitone modulation. G.DMT full-rate ADSL expands the usable bandwidth of existing copper telephone lines, delivering high-speed data communications at rates up to 8 Mbit/s downstream and 1.3 Mbit/s upstream.DMT...

) performance of a network

Computer network

A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....

. Another potential application of DSM is for cognitive radio

Cognitive radio

A cognitive radio is a kind of two-way radio that automatically changes its transmission or reception parameters, in a way where the entire wireless communication network -- of which it is a node -- communicates efficiently, while avoiding interference with licensed or licensed exempt users...

.

Important and common principles of DSM include:

1. link adaptation
   Link adaptation
   Link adaptation, or adaptive coding and modulation , is a term used in wireless communications to denote the matching of the modulation, coding and other signal and protocol parameters to the conditions on the radio link Link adaptation, or adaptive coding and modulation (ACM), is a term used in...
   
   
2. bandwidth management
3. Multi-user MIMO
4. pre-cancellation of estimated interference
5. combining unused channels (not pre-allocated) for a single user
   Link aggregation
   Link aggregation or trunking or link bundling or Ethernet/network/NIC bonding or NIC teaming are computer networking umbrella terms to describe various methods of combining multiple network connections in parallel to increase throughput beyond what a single connection could sustain, and to provide...
   
    or bonding
   Channel bonding
   Channel bonding is a computer networking arrangement in which two or more network interfaces on a host computer are combined for redundancy or increased throughput....
   
   

DSM in Digital Subscribers Loop

DSM can be achieved over ordinary copper phone lines' network by reducing or eliminating crosstalk

Crosstalk (electronics)

In electronics, crosstalk is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel...

, interference

Interference (communication)

In communications and electronics, especially in telecommunications, interference is anything which alters, modifies, or disrupts a signal as it travels along a channel between a source and a receiver. The term typically refers to the addition of unwanted signals to a useful signal...

 and near-far problem

Near-far problem

The near-far problem or hearability problem is a situation that is common in wireless communication systems, in particular, CDMA. In some signal jamming techniques, the near-far problem is exploited to disrupt communications.-Technical explanation:...

 within a DSL network especially affecting the DSL phone lines that are close together in a binder

25-pair color code

The 25-pair color code is a color code used to identify individual conductors in a kind of electrical telecommunication wiring for indoor use, known as twisted pair cables . The colors are applied to the insulation that covers each conductor...

.

The technique involves multiple methods:

1. continuously monitoring the status of interfering signal levels using current bit-loading compared to Maximum achievable bit rate
   Bit rate
   In telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time....
   
   , number of errored seconds, number of severely errored seconds, number of FEC
   Forward error correction
   In telecommunication, information theory, and coding theory, forward error correction or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels....
   
    and making decisions about the underperforming scenarios cause and forcing the link to train in a specific way.
2. identifying the neighborhood cables in the binders that may be causing unwanted cross-talk and lowering their upstream
   Upstream (networking)
   In computer networking, upstream refers to the direction in which data can be transferred from the client to the server . This differs greatly from downstream not only in theory and usage, but also in that upstream speeds are usually at a premium...
   
    transmission power till bit-rates are optimized for the network.
3. increasing or decreasing the amount of forward error correction overhead applied to the signal propagating on the cable in response to the severity of the correlated interferers or jammers.
4. modifying the limits on the power levels allowed on cable, the masks of the tones on which bits can be loaded or the masks for Power Spectral Density to allow for minimization of the interference caused due to excess SNRs causing degradation of SNR on other lines.
5. modem hardware (consumer premises equipment
   ADSL transceiver
   A digital subscriber line modem is a device used to connect a computer or router to a telephone circuit that has digital subscriber line service configured. Like other modems, it is a type of transceiver. It is also called a DSL transceiver or ATU-R...
   
   ) adjusting transmission settings in order to achieve the optimized DMT signal (this is not exactly DSM and can be achieved even without DSM). This hardware adjustment being forced from a central monitoring location
   Network Operations Center
   A network operations center is one or more locations from which control is exercised over a computer, television broadcast, or telecommunications network....
   
    applied to a network of consumer premises equipment on the whole to optimize the network performance as a whole.

External links

• Boost for Internet speeds without fibre-optics
• ECI Telecom sets out to double DSL speed
• DSM project — Prof. John Cioffi
• Fast Copper Project — Princeton University
  Princeton University
  Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
  
  
• Dynamic Spectrum Management Publications — Raphael Cendrillon