Effect of FEC mechanisms in the performance of low bit rate codecs in lossy mobile environments

Hernández²

2019

IET wirel. sens. syst.

Self Cite

The Internet Engineering Task Force (IETF) has developed and promoted several standards intended to facilitate Internet of things communication among constrained devices in low-power low-rate networks (LLNs). Specifically, IETF introduces a series of protocols that deal with different layers of the stack ranging from IPv6 adaptation to routing in LLN. Among them, the constrained application protocol (CoAP) is a session protocol that is used to carry sensor and actuator traffic. Since CoAP transport relies on the user datagram protocol, and in order to provide reliability, it introduces a mode operation known as confirmable where messages are considered delivered once they have been acknowledged. One drawback of this approach, however, is the latency that results from the retransmission of packets in lossy networks. In this study, the authors present, model, compare and evaluate a forward error correction mechanism that enables CoAP to improve its reliability while reducing latency.

Section: Coap Fec Analytical Modelmentioning

confidence: 99%

Forward error correction in real‐time Internet of things CoAP‐based wireless sensor networks

Hernández²

2019

IET wirel. sens. syst.

Self Cite

“…One of the characteristics of wireless RTIoT networks is that they are affected by dynamic multipath fading that is typically modeled by means of a 2‐state Markov process. () Essentially, the channel is either in a low loss (L) or in a high loss (H) state, as shown in Figure . As expected, when comparing packet loss in both states, that in the low‐loss state is much lower than that in the high‐loss state.…”

Section: Theoretical Frameworkmentioning

confidence: 99%

Encapsulation of real‐time IoT CoAP traffic

Trans Emerging Tel Tech

2018

Self Cite

The Constrained Application Protocol (CoAP) has been instrumental to the deployment of wireless sensors and actuators in Internet of Things low‐power low‐rate networks. Typically, a large number of such devices interact with a single gateway that routes traffic to servers where complex processing is performed. CoAP provides a highly efficient end‐to‐end mechanism that relies on the User Datagram Protocol for transport, and it is characterized by both low throughput and low latency. Because Internet firewalls typically filter User Datagram Protocol traffic as it traverses from gateways to servers, the use of Transmission Control Protocol (TCP) encapsulation becomes a viable alternative. This solution, however, is negatively affected by network packet loss that, due to TCP inherent retransmissions, severely degrades latency, reducing system responsibility. In this paper, we analyze the effect of TCP‐encapsulated CoAP and propose a mechanism that overcomes these limitations without having to change network topologies or modifying protocol functionality.

“…Both mechanisms are taken in the context of a dynamic multipath environment that leads to fading channels . These channels are modelled by a two‐state Markov process [18] that follows the diagram as shown in Fig. 2.…”

Section: Analytical Modelmentioning

confidence: 99%

Analytical model of stream transported media

St-Pierre²

2017

IET Networks

Self Cite

For transmission of packetised media, real-time communications rely on the real-time protocol (RTP). RTP traffic, however, is transmitted over datagram-based transport that allows fast delivery of media. Internet firewalls are typically configured to allow web friendly traffic that uses stream-based transport instead and, simultaneously as security measure, reject any other type of transport. A mechanism to overcome this limitation is by switching transport such that media frames that would be rejected by firewalls are transmitted on top of stream transport. In this study, a novel mathematical model that links application layer packet loss to bursty network packet loss in the context of fading channels characteristic of wireless communications is presented for both, datagram and stream transport. This model is compared with experimental scenarios applied to state-of-the-art speech codecs in order to obtain quality scores that can be correlated against theoretical loss probabilities.