How does automatic repeat request work?

How does automatic repeat request work?

Automatic repeat request (ARQ), also known as automatic repeat query, is an error-control method for data transmission that uses acknowledgements (messages sent by the receiver indicating that it has correctly received a packet) and timeouts (specified periods of time allowed to elapse before an acknowledgment is to be …

Where is automatic repeat request used?

Automatic Repeat ReQuest (ARQ) is a group of error – control protocols for transmission of data over noisy or unreliable communication network. These protocols reside in the Data Link Layer and in the Transport Layer of the OSI (Open Systems Interconnection) reference model.

What are the ARQ strategies?

ARQ is an error-control strategy used in a two-way communication system. It is a group of error-control protocols to achieve reliable data transmission over an unreliable source or service. These protocols reside in Transport Layer and Data Link Layer of the OSI(Open System Interconnection) model .

What are three popular ARQ mechanisms?

Three main types of the ARQ are the Stop-and-wait ARQ, Go-Back-N ARQ, and Selective Repeat ARQ. Stop-and-wait ARQ is the simplest ARQ.

What is ARQ and FEC?

Hybrid automatic repeat request (hybrid ARQ or HARQ) is a combination of high-rate forward error correction (FEC) and automatic repeat request (ARQ) error-control. In standard ARQ, redundant bits are added to data to be transmitted using an error-detecting (ED) code such as a cyclic redundancy check (CRC).

What is a HARQ process?

HARQ process relies upon receiving ACK for the packets. If the sender sends a packet and then waits for the ACK to send another packet, it is called a SAW(stop and wait) process. It increases the round trip time ( sender and receiver processing time + propagation delays).

What is automatic repeat request ARQ?

Automatic Repeat Request (ARQ) is an error-control mechanism for data transmission which uses acknowledgements (or negative acknowledgements) and timeouts to achieve reliable data transmission over an unreliable communication link.

At what layer does ARQ exist?

layer 2 data link protocol
The ARQ is a layer 2 data link protocol (see OSI model). The sender waits for an acknowledgment (ACK) before sending the next frame. If the sender does not receive an ACK within a certain amount of time, or if it receives a not-acknowledged (NAK) message, the frame is retransmitted.

What is soft combining?

Soft Combining is an error correction technique in which the bad packets are not discarded but stored in a buffer. The basic idea is that 2 or more packets received with insufficient information can be combined together in such a way that total signal can be decoded.

What is ARQ in 5g?

ARQ stands for Automatic Repeat Request. This is the protocol used at data link layer. It uses CRC to determine whether the packet received is correct or not. If the packet is received correctly receiver send ACK to the transmitter, but if the packet is received incorrectly receiver send NACK to the transmitter.

What is the difference between ARQ and FEC?

The difference between ARQ and FEC is that ARQ wastes the bandwidth by using retransmission, whereas FEC requires additional redundancy in the transmitted information and incurs significant processing complexity in performing the error correction.

https://www.youtube.com/watch?v=POJEnhKj87A