Found 826 Articles for Network

A mode in HDLC is the realigning between two machines contained in a network. The mode describes who controls the link. HDLC determines three types of stations such as primary, secondary, and combined.A primary station is a controlling station on a connection. It controls the secondary stations on the connection and handles data flow and error recovery.A secondary station as existing on a connection where there is a primary station. The secondary station is contained by the primary station and has no explicit authority for maintaining the connection.A combined station is a combination of primary and secondary stations.HDLC Operational ModesThere ... Read More

The HDLC process is regulated by the International Organization for Standardization (ISO). This is possible for high-speed communication of a high amount of information. The necessary control process cannot support this communication.The HDLC process has been regulated and established on the SDLC. In addition to the characters, bit strings of the acquired length can also be sent through this process. The unit of data communication is known as a frame.HDLC Frame StructureTo provide support for all options in the mode and configuration, HDLC defines three types of frames.Information Frames (IF)The I-Frame is as follows −FlagAddressControl  User Information   FCS Flag        ... Read More

Synchronous protocols take the whole bitstream and drop it into the character of equal size. It is a data transfer approach in which it is a continual flow of information signals followed by computing signal. These protocols facilitate the provision that the broadcaster and the receiver are integrated. This transmission approach is mainly used when vast amounts of record are needed to be moved from one area to another. There are two types of synchronous protocol which are as follows − Character Oriented Protocols It is also called as the byte-oriented protocol to interpret a transition frame or packet as ... Read More

The Hamming code can be used to the data units of any length when we consider the two codewords which have the same length. The Hamming distance between two codewords is represented as the number of positions in which their specific item differs.ExampleHamming Distance is 3.Hamming code is also known as linear block code. The family of (n, k) hamming codes for m  is defined.Block length n=2m-1.The number of message bits k=2m-m-1.Number of Parity Bits = n-k=m.Where m≥3Minimum distancemin=3.Code rate = Code efficiency = $\frac{k}{n} = \frac{2^{m}-m-1}{2^{m}-1} = 1 - \frac{m}{2^{m}-1}$ of m>> 1then, code rate r=1 where k is ... Read More

In the detection method, only the error can be detected. Still, in the error correction method, the errors are corrected automatically at the receiver end and no need for re-transmission.  The burst error correction is very limited to 2 bits only.Each kbit block of data is added with redundant bits that make a codeword of n bits (n > k). A forward error correction encoder is used on the transmission end. Then, the codeword is transmitted. The signal is demodulated to make a bit string equivalent to the initial codeword to include the errors at the receiver.If no bit error, ... Read More

The Cyclic Redundancy Checks (CRC) is the most powerful method for Error-Detection and Correction. It is given as a kbit message and the transmitter creates an (n – k) bit sequence called frame check sequence. The out coming frame, including n bits, is precisely divisible by some fixed number. Modulo 2 Arithmetic is used in this binary addition with no carries, just like the XOR operation.Redundancy means duplicacy. The redundancy bits used by CRC are changed by splitting the data unit by a fixed divisor. The remainder is CRC.Qualities of CRCIt should have accurately one less bit than the divisor.Joining ... Read More

Parity Bit is the simplest and frequently used method for detecting an error. In this method, we have to join a parity bit to the end of the data structure. The bit is so chosen that the weight of codeword is either even or odd of, i.e. V is the cost of this bit is chosen therefore that the character has an even number of 1's called even parity or an odd number of 1's known as odd parity.For Example,  If the transmitter is transmitting 1110001 and using odd parity. It willappend 1 in sorting. The receiver determines the received ... Read More

There are a few effects of errors which are as follows −Attenuation: Due to error, the signal may get attenuated, i.e., the data may be costly in the extreme case.Delay Distortion: Due to this error at the receiving end, the wave is distorted due to a delay in transmission.Interference in voice communication can occur due to an error in the signal.Echo can be produced because the sender cannot hear the receivers answer or voice.Cross talk can occur because of the error in the broadcasted signal. Due to this, the faint voice of another party may disturb your signal.Data Error Rate:  (P10):Probability that ... Read More

It makes use of the lower gigahertz frequencies of the electromagnetic spectrum. These frequencies are higher than radio frequencies, and they make better throughput and execution. This transmission can be further classified as Terrestrial or Satellite.Types of Microwave TransmissionThere are two types of microwave transmission, which are as follows.Terrestrial Microwave TransmissionThese systems use directional parabolic antennas to transmit and receive signals in the lower gigahertz range, as shown in the figure. These signals are highly focussed and travel insight. Relay towers can extend signals. Smaller terrestrial microwaves systems can be used inside a building. Some microwave LANS works at low ... Read More

The electromagnetic waves having frequencies between 1 and 300 GHz are known as a microwave. Microwave systems use very high-frequency radio or television signals to transmit data through space. Therefore, the transmitter and receiver of a microwaves system, which is mounted on very high towers, should be invisible to each other, i.e., they both should be in a line-of-sight. Moreover, the signals become weak after travelling a certain distance and require power amplification.Microwave systems can carry large quantities of data at high rates of speed. The data transmission rate is about 16 gps (Gigabits per second). A microwave system can ... Read More