If the signal to noise ratio (SNR) allows digital modulation method may be used where more than two possible states per symbol, such as QPSK or QAM. The transmission speed is then obtained as the product of the step rate and the number of possible states, ie the number of bits per step as shown in Network Configuration and Change Management.

Usually receives a digital signal, a two states, which can be described as “0” and “1”. This is called binary. Three states is denoted by ternary. At the same bitrate and three states for the signal parameters, the required bandwidth is still only 63% of the bandwidth is required for binary transmission.

SNR and bandwidth are complementary. A predetermined data transfer rate can be achieved in both a transmission channel with limited bandwidth and large signal to noise ratio as well as those having a lower signal to noise ratio, but correspondingly larger bandwidth.

It is essential that this law only white noise whose amplitudes are normally distributed, is considered. It refers to those disturbance as additive white Gaussian noise, as additive white gaussian noise or AWGN. Transmission channels, which have only these disorders and can be characterized with that equation are therefore also referred to as the AWGN channel. In other interference with the distribution of the noise signal, this relationship no longer holds.

Grid computing (grid – lattice network) is a form of distributed computing in which a virtual supercomputer is presented in the form of clusters connected by a Network Configuration and Change Management of loosely coupled, heterogeneous computers working together to perform a huge number of tasks.

This technology is used for scientific and mathematical problems requiring significant computing resources. Grid computing is also used in commercial infrastructure solutions for time-consuming tasks such as economic forecasting, development and study of the properties of new drugs.

Grid from the point of view of the network organization is a consistent, open and standards-based environment that provides a flexible, secure, coordinated division of computing and storage resources information that are part of that environment, within a single virtual organization.

Grid is a geographically distributed infrastructure, uniting many different types of resources (processors, and long-term memory, storage, and network database), access to which user can get from anywhere, regardless of their location.

The idea of grid computing has arose with the proliferation of personal computers, the development of Internet technologies and packet data based on optical fiber (SONET, SDH and ATM), as well as local area network technologies (Gigabit Ethernet). Bandwidth communication tools have become sufficient to attract resources, if necessary, another computer.