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Coding
Published in Goff Hill, The Cable and Telecommunications Professionals' Reference, 2012
In feedback error correction, for which only block codes can be used, the receiver only attempts to detect errors and sends return messages to the sender, which cause repeat transmission if any errors are detected in a received block. In the OSI model for packet data networks, this function is carried out within the data link layer by the return to the sender of a positive or negative acknowledgement (ACK or NAK) on receipt of a data block; this is known as stop-and-wait ARQ (Automatic Repeat Request). In go-back-N ARQ, receipt of a NAK by the transmitter makes it retransmit the erroneous codeword and the N–1 that follow, where N is chosen so that the time taken to send N codewords is less than the round-trip delay from transmitter to receiver and back again. This obviates the need for a buffer at the receiver. In selective-repeat ARQ, only the codewords for which NAKs have been returned are retransmitted. Performance analysis (Lin & Costello, 1983) shows that this is the most efficient system, although it requires an adequately large buffer in the receiver.
Data Link Layer
Published in Mário Marques da Silva, Cable and Wireless Networks, 2018
The Selective Reject ARQ is similar to the Go-Back-N ARQ. In both cases, the transmission window is higher than 1, consisting of a value that is a function of the propagation time. Nevertheless, while in the case of the Go-Back-N ARQ the receiving window is 1 (the receiver discards all frames after a corrupted received frame), in the Selective Reject ARQ the receiving window is such that the received frames after a corrupted one are stored in a memory. When the receiver rejects a certain corrupted frame (REJ n), the transmitting entity only resends a certain corrupted frame, returning to the normal transmission sequence (i.e., the transmitting entity does not retransmit all frames after a corrupted one).
Performance analysis of LT code-based HARQ error control in underwater acoustic sensor networks
Published in Journal of Marine Engineering & Technology, 2022
P. Kaythry, R. Kishore, V. Nancy Priyanka
To validate the proposed RLTCH protocol, the simulations are carried out in NS2 platform using UWSN package extension Aqua-sim (Peng et al. 2009). Performance results are compared with the existing protocols such as RBLC and Recursive LT codes in terms of energy consumption, delay, network throughput and control overhead. RLTCH code is applied on sensed data and encoded data is transmitted between any two nodes simulated for multi-hop UASN scenario. Parameters used for simulation are presented in Table 1. For simulation, 100 nodes are randomly deployed in 500 m × 500 m × 500 m area. Also, the average number of hops from source to destination node is set as 5, the transition time as 6 s and the packet interval as 0.3 s. Initial battery power of the nodes is set to 70J. The decoding failure probability µ is set to 0.05. Acknowledgment packet size is set to 6 bytes and data packet size is set as 60 bytes. Simulation time is set to 500 s. Selective repeat ARQ is combined with RLT code for reliability and energy efficiency to implement hop-by-hop error control method.