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Keywords = retransmission timeout (RTO)

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22 pages, 3029 KiB  
Article
FaCoCo-RED: A Fast Response Congestion Control Mechanism for Constrained Application Protocol
by Chanwit Suwannapong, Sarutte Atsawaraungsuk, Kritsanapong Somsuk and Pitsanu Chaichitwanidchakol
Electronics 2025, 14(1), 28; https://doi.org/10.3390/electronics14010028 - 25 Dec 2024
Viewed by 771
Abstract
The rapid growth of the Internet of Things (IoT) has contributed to significant challenges in dealing with congestion within IoT communications due to high packet error rates, latency, and interference in networks. With an emphasis on the Constrained Application Protocol (CoAP), the present [...] Read more.
The rapid growth of the Internet of Things (IoT) has contributed to significant challenges in dealing with congestion within IoT communications due to high packet error rates, latency, and interference in networks. With an emphasis on the Constrained Application Protocol (CoAP), the present study aims to propose the design and development of a novel congestion control mechanism, namely, Fast Response Congestion Control—Random Early Detection, abbreviated as FaCoCo-RED, along with performance analysis and comparison of congestion management efficacy between FaCoCo-RED and Default CoAP Congestion Control (Default CoAP CC) under a Cooja simulator on the Contiki OS platform. The findings from both experiment and performance analysis, which were based on statistical testing, showed that, under medium-scale to large-scale node networks across all traffic scenarios in this study, FaCoCo-RED significantly outperformed Default CoAP CC. The improvement can be seen in such metrics as average throughput, packet loss, response time, settling time, and retransmission timeout values (RTOs). The experimental findings also showed that FaCoCo-RED can perform effectively within the IoT networks, thus potentially enhancing the reliability and scalability of CoAP for large-scale and more complex IoT applications in the future. Full article
(This article belongs to the Section Computer Science & Engineering)
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16 pages, 3247 KiB  
Article
Improving Congestion Control of TCP for Constrained IoT Networks
by Chansook Lim
Sensors 2020, 20(17), 4774; https://doi.org/10.3390/s20174774 - 24 Aug 2020
Cited by 26 | Viewed by 3885
Abstract
For smooth integration with middleboxes on the Internet, TCP (Transmission Control Protocol) is favorably considered as a transport-layer protocol for IoT (Internet of Things) networks. In constrained networks, TCP tends to perform well with a small window size. For example, the uIP (micro [...] Read more.
For smooth integration with middleboxes on the Internet, TCP (Transmission Control Protocol) is favorably considered as a transport-layer protocol for IoT (Internet of Things) networks. In constrained networks, TCP tends to perform well with a small window size. For example, the uIP (micro IP) TCP/IP stack sets the TCP window size to one segment by default. In such a case, managing the retransmission timer is a primary approach to congestion control. In this paper, we examine the congestion control mechanism of TCP in the uIP stack using grid topology networks. In the preliminary test using the Cooja network simulator, the results show that the original uIP TCP causes lots of retransmissions when a radio duty cycling mechanism such as ContikiMAC is used. One main reason is that, once retransmission is deemed to be necessary, the original uIP TCP sets the retransmission timer based on the fixed RTO (retransmission timeout) before performing a retransmission. Since ContikiMAC may cause large RTT (round-trip time) variations due to the hidden terminal problem, the retransmission timer based on the fixed RTO value may cause lots of retransmissions. To address the problem, we propose a new scheme for managing the retransmission timer which adopts the notion of weak RTT estimation of CoCoA, exponential backoffs with variable limits, and dithering. Simulation results show that our proposed scheme reduces retransmissions while enhancing throughput and fairness when an RDC (radio duty cycling) mechanism is used. Full article
(This article belongs to the Section Internet of Things)
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14 pages, 2611 KiB  
Article
Congestion Control in CoAP Observe Group Communication
by Chanwit Suwannapong and Chatchai Khunboa
Sensors 2019, 19(15), 3433; https://doi.org/10.3390/s19153433 - 5 Aug 2019
Cited by 29 | Viewed by 5513 | Correction
Abstract
The Constrained Application Protocol (CoAP) is a simple and lightweight machine-to-machine (M2M) protocol for constrained devices for use in lossy networks which offers a small memory capacity and limited processing. Designed and developed by the Internet Engineering Task Force (IETF), it functions as [...] Read more.
The Constrained Application Protocol (CoAP) is a simple and lightweight machine-to-machine (M2M) protocol for constrained devices for use in lossy networks which offers a small memory capacity and limited processing. Designed and developed by the Internet Engineering Task Force (IETF), it functions as an application layer protocol and benefits from reliable delivery and simple congestion control. It is implemented for request/response message exchanges over the User Datagram Protocol (UDP) to support the Internet of Things (IoT). CoAP also provides a basic congestion control mechanism. In dealing with its own congestion, it relies on a fixed interval retransmission timeout (RTO) and binary exponential backoff (BEB). However, the default CoAP congestion control is considered to be unable to effectively perform group communication and observe resources, and it cannot handle rapid, frequent requests. This results in buffer overflow and packet loss. To overcome these problems, we proposed a new congestion control mechanism for CoAP Observe Group Communication, namely Congestion Control Random Early Detection (CoCo-RED), consisting of (1) determining and calculating an RTO timer, (2) a Revised Random Early Detection (RevRED) algorithm which has recently been developed and primarily based on the buffer management of TCP congestion control, and (3) a Fibonacci Pre-Increment Backoff (FPB) algorithm which waits for backoff time prior to retransmission. All the aforementioned algorithms were therefore implemented instead of the default CoAP mechanism. In this study, evaluations were carried out regarding the efficiency of the developed CoCo-RED using a Cooja simulator. The congestion control mechanism can quickly handle the changing behaviors of network communication, and thus it prevents the buffer overflow that leads to congestions. The results of our experiments indicate that CoCo-RED can control congestion more effectively than the default CoAP in every condition. Full article
(This article belongs to the Section Sensor Networks)
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13 pages, 1163 KiB  
Article
Gateway-Assisted Retransmission for Lightweight and Reliable IoT Communications
by Hui-Ling Chang, Cheng-Gang Wang, Mong-Ting Wu, Meng-Hsun Tsai and Chia-Ying Lin
Sensors 2016, 16(10), 1560; https://doi.org/10.3390/s16101560 - 22 Sep 2016
Cited by 10 | Viewed by 5962
Abstract
Message Queuing Telemetry Transport for Sensor Networks (MQTT-SN) and Constrained Application Protocol (CoAP) are two protocols supporting publish/subscribe models for IoT devices to publish messages to interested subscribers. Retransmission mechanisms are introduced to compensate for the lack of data reliability. If the device [...] Read more.
Message Queuing Telemetry Transport for Sensor Networks (MQTT-SN) and Constrained Application Protocol (CoAP) are two protocols supporting publish/subscribe models for IoT devices to publish messages to interested subscribers. Retransmission mechanisms are introduced to compensate for the lack of data reliability. If the device does not receive the acknowledgement (ACK) before retransmission timeout (RTO) expires, the device will retransmit data. Setting an appropriate RTO is important because the delay may be large or retransmission may be too frequent when the RTO is inappropriate. We propose a Gateway-assisted CoAP (GaCoAP) to dynamically compute RTO for devices. Simulation models are proposed to investigate the performance of GaCoAP compared with four other methods. The experiment results show that GaCoAP is more suitable for IoT devices. Full article
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33 pages, 1515 KiB  
Article
Improving Packet Delivery Performance of Publish/Subscribe Protocols in Wireless Sensor Networks
by Ernesto García Davis, Anna Calveras and Ilker Demirkol
Sensors 2013, 13(1), 648-680; https://doi.org/10.3390/s130100648 - 4 Jan 2013
Cited by 54 | Viewed by 9848
Abstract
MQTT-S and CoAP are two protocols able to use the publish/subscribe model in Wireless Sensor Networks (WSNs). The high scalability provided by the publish/subscribe model may incur a high packet loss and therefore requires an efficient reliability mechanism to cope with this situation. [...] Read more.
MQTT-S and CoAP are two protocols able to use the publish/subscribe model in Wireless Sensor Networks (WSNs). The high scalability provided by the publish/subscribe model may incur a high packet loss and therefore requires an efficient reliability mechanism to cope with this situation. The reliability mechanism of MQTT-S and CoAP employs a method which defines a fixed value for the retransmission timeout (RTO). This article argues that this method is not efficient for deploying publish/subscribe in WSN, because it may be unable to recover a packet, therefore resulting in a lower packet delivery ratio (PDR) at the subscriber nodes. This article proposes and evaluates an adaptive RTO method, which consists in using a Smooth Round-trip Time and multiplying it by a constant parameter (K). Thanks to this method, the reliability mechanism of MQTT-S and CoAP would be able to react properly to packet loss and would also be lightweight in terms of energy, memory and computing for sensor nodes where these resources are critical. We present a detailed evaluation of the effects of the K value on the calculation of the adaptive RTO method. We also establish the setting for obtaining the highest PDR on the subscriber nodes for single-hop and multi-hop scenarios. The results for single-hop scenario show that use of the appropriate K value for the adaptive RTO method increases the PDR up to 76% for MQTT-S and up to 38% for CoAP when compared with the use of fixed RTO method for both protocols, respectively. Meanwhile the same comparison for multi-hop scenario, the adaptive RTO method increases the PDR up to 36% for MQTT-S and up to 14% for CoAP. Full article
(This article belongs to the Section Sensor Networks)
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