Bandwidth in Computing

Bandwidth in Computing or colloquially transmission speed, is referred to the digital data set transmitted per unit of time through a transmission channel. The maximum data transmission rate that can be transmitted error-free over a channel is called channel capacity. This, together with the latency time is a measure of the performance of the channel (delay response). A channel can, for example, a connection in the computer network to connect to the ISP or the interface to a data store to be.

 

Bandwidth in Computing : Dimensions of the Data Transfer Rate

 

The data transmission rate is measured by counting data units per unit time. The smallest unit of data is the bit, which is why they often used as bit rate (bit/s) is given in units of bits per second. Multiples of this unit can with unit resolutions are formed, for example, is 1 kbit/s for 1000 bit/ s with data transfer rates, the unit resolutions are traditionally used in their SI-compliant decimal significance.

Thus, for example Gigabit Ethernet transmits data at 125 Mbps through the 5-PAM modulation scheme with 2-bit per symbol pair and four pairs 1,000,000,000 bits/s. The same applies to data rates of audio. Chance of unit resolutions are also used in a hybrid binary / decimal significance in recent times.

In areas where a parallel data transmission is used especially when accessing data memory via a data bus, the transmission rate also common in bytes per second, which usually multiples of 8 bits are meant per second, so you have to make sure whether a transmission rate, for example, with 1 MB / s or 1 Mbit/s is specified.

 

Bandwidth in Computing : Relationship Between Data Rate and Bandwidth

 

Between bandwidth and maximum data transfer rate there is a fixed relationship. For a transmission channel with bandwidth B and the signal to noise ratio SNR with additive white Gaussian noise, the maximum achievable error-free data transmission rate is available in the following context : It is essential that this law is valid only with white noise whose amplitude is normally distributed.

It refers to those disturbance as additive white Gaussian noise, in English as additive white gaussian noise. 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 remains valid.

The transmission speed then obtained as the product of the step velocity and the number of possible states, i.e. the number of bits per step. 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, which is necessary 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.

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