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Error Control Coding
Published in Jerry D. Gibson, Mobile Communications Handbook, 2017
Error control schemes can be broadly classified into two categories: Forward error control (FEC) codes, in which sufficient redundancy is incorporated into the “forward” (transmitter-to-receiver) transmission to enable the receiver to recover the data well enough to meet the requirements of the application.Automatic repeat request (ARQ), in which enough redundancy is incorporated into the forward transmission to enable the receiver to detect the presence of corruption—but not enough to reliably estimate the data from the (corrupted) received signal. ARQ schemes employ a retransmission strategy in which the receiver alerts the transmitter (via an “ACK/NACK” protocol on a feedback channel) of the need to retransmit the corrupted data.
Traffic Management in Wireless Sensor Networks
Published in Ioanis Nikolaidis, Krzysztof Iniewski, Building Sensor Networks, 2017
Swastik Brahma, Mainak Chatterjee, Shamik Sengupta
Table 5.1 shows the parameter values used in the simulations. We assumed that the maximum communication channel bit rate is 38.4 kbps, the ACK packet is 5 bytes, the beacon packet is 10 bytes, and data packets are 64 bytes. The simulations have been carried out on a 100-node network, a 10 × 10 grid, with the sink at the lower-left corner. The topology is shown in Figure 5.4. The nodes have been initialized with an initial packet-generation rate of 1 packets/s. Each link has a constant loss probability of 0.1, which is in addition to the loss caused by interference. Since ARQ (Automatic Repeat reQuest) is implemented, packets dropped due to interference or queue overflow are retransmitted. The weights used in the exponential moving-average calculation of the output and input rate (see Section 5.4.2.1 and Section 5.4.2.2) is set to 0.1. Each node has a queue to hold packets forwarded by its children, as well as packets generated by itself. This queue has been set to hold a maximum of 25 packets.
Green Relay Techniques in Cellular Systems
Published in F. Richard Yu, Xi Zhang, Victor C. M. Leung, Green Communications and Networking, 2016
Yinan Qi, Fabien Heliot, Muhammad Ali Imran, Rahim Tafazolli
Despite the exploitation of an efficient cooperative relaying strategy the transmitted packet might be lost due to the instantaneous channel condition and noise realization. The packet loss could be even more severe when the system is operating under static (block) fading condition and the transmitter is not able to properly tune its transmission rate due to the lack of sufficient level of channel knowledge. Retransmission techniques based on automatic repeat request, i.e., ARQ [50-52] and its advanced hybrid types that combine forward error correction (FEC) with ARQ by keeping previously received packets for detection, commonly known as hybrid ARQ (HARQ), will be the natural choices to circumvent this problem and guarantee correct data packet delivery to the final destination. Common encoding techniques for HARQ are repetition coding (RC) which chase combing and unconstrained coding (UC) with incremental redundancy (INR), respectively [53-55]. The emphasis of this section is on HARQ, specifically INR as it is capable of offering higher throughput [56]. As the repetition coding based HARQ performs weaker than INR and the extension of the presented analysis to repetition coding is a straightforward practice, it will not be considered in this section.
Performance analysis for Bernoulli feedback queues subject to disasters: a system with batch Poisson arrivals under a multiple vacation policy
Published in Quality Technology & Quantitative Management, 2023
George C. Mytalas, Michael A. Zazanis
In the context of the model analyzed in the present paper, the server corresponds to the CMCU, the Poisson input of batch arrivals corresponds to the stream of aggregated data transmitted to the satellite-based CMCU from the vehicles and ground-based stations. After processing, data are transmitted back to the stations. The possibility of feedback arises from the use of an ARP (Automatic Repeat reQuest) protocol, according to which if the transmitting node does not receive an acknowledgment before timeout, it re-transmits the frame/packet until the acknowledgement is received. Including a Poisson stream of disasters in our model is essential in this case since satellite systems are subject to atmospheric and electromagnetic disturbances which may wipe out data or, by causing long interruptions in communication, render the data irrelevant. Finally, since the CMCU also performs secondary tasks, this necessitates the inclusion of vacations in the model. Models of satellite nodes of this type may be more effective if they can incorporate the interplay of the above factors and the present paper is a step in that direction.
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
The ARQ technique totally works on retransmission of corrupted and lost packets based on the acknowledgement (ACK) received from the receiver or the time outs occur with respect to the sender (Lee and Cho 2011). Long propagation delay and error rate in UASN restricts the adoption of ARQ protocol, which introduces longer end-to-end delay, retransmission overheads and consumes more energy as well as bandwidth. Hybrid Automatic Repeat reQuest (HARQ) combines FEC for error detection and ARQ for retransmission of erroneous data in UASN. The sensed data in any UASN applications are sent from the source node to destination node over multiple hops. In this paper, the rateless code-based hop-by-hop HARQ scheme is proposed and investigated for reliable data transmission in UASN. The proposed method combines Recursive Luby transforms (LT) code, a simple rate less code-based FEC with hop-by-hop selective retransmission. The source node uses LT code to encode the original input packets into a set of ‘N’ encoded packets. Let ‘N’ be the sum of the number of redundant packets (m) and a number of input packets (n) i.e. ‘N=m+n’. To retrieve the ‘n’ original packets, the receiving node must receive ‘N’ encoded packets, which is greater than original packets ‘n’. During encoded packet transmission if more than ‘m’ packets are lost, the receiver discard the encoded packets and sends a feedback Negative Acknowledgement (NACK) packet and makes use of end-to-end ARQ retransmission technique.
Analysis of adaptive multi-rate FSO/RF hybrid systems using Málaga-ℳ distribution model in turbulent channels
Published in Journal of Modern Optics, 2020
Mohammad Reza Aghaei, A. M. Afshin Hemmatyar, Abolfazl Chamanmotlagh, Majid Fouladian
In this section, one of the most critical issues in the implementation of adaptive multi-rate (AMR) applications in the system will be demonstrated and it is the matter of designing switching threshold level (calculating , ). We describe a multi-layer design based on the combination of the physical layer and the data link layer with automatic repeat request (ARQ). Previous articles confirm the superiority of AMR methods over conventional methods and suggest that the multilayer layout is more efficient than the physical layer [14,16,19,20].