A Scheduling Method Based on Packet Combination to Improve End-to-End Delay in TSCH Networks with Constrained Latency

Wireless sensor networks (WSN) are networks for gathering data from sensor nodes that have been applied in industry for a long time. In real-time industrial applications with tight latencies, schedulability is one of the most critical issues. Some authors have proposed centralized scheduling algorithms for time-slotted channel hopping (TSCH) networks for real-time applications in industry, however, they have some disadvantages such as schedulability and high data traffic. In this paper, we improve the schedulability, latency, data traffic by dynamically prioritizing packets which are based on number duplex-conflicts and dynamically combining the packets. As a result, we show that the packet-combining algorithm improves schedulability and minimizes the amount of traffic in a network when compared with existing approaches.

Throughput Analysis of Energy-Efficient Combined Packet Combining-Aggressive Packet Combining Scheme in Two State Scenarios

Packet combining (PC) and aggressive packet combining (APC) are studied earlier in several kinds of literature. Both schemes have shortcomings to achieve higher throughput. In this paper, PC-APC scheme is proposed to attain higher throughput. Combination of these two schemes shows the remarkable result in some of the cases based on the state of the communication channel. Also the rate of erroneous packet delivery decrease in this scheme. Here the benefits of both schemes (PC and APC) are obtained as well as it eliminates the detriments. The comparisons of PC, APC and PC-APC schemes with respect to bandwidth and power consumption issues are particularly focused on. Throughput can be optimized through PC-APC assisted schemes.

Performance Evaluation of HARQ Schemes for the Internet of Things

Hybrid Automatic Repeat reQuest (HARQ) techniques are widely employed in the most important wireless systems, e.g., the Long Term Evolution (LTE) cellular standard, to increase the reliability of the communication. Despite these schemes have been widely studied in literature in the past several years, the recent results obtained by Polyanskiy, Poor, and Verdú on the finite-blocklength regime disclosed new possibilities for the research on HARQ schemes. Indeed, new communications trends, which are usually part of the Internet of Things (IoT) paradigm, are characterized by very short packet sizes and a high reliability requirement and, therefore, they call for efficient HARQ techniques. In many scenarios, the energy efficiency of the communication plays a key role as well. In this paper, we aim at providing a comprehensive performance comparison of various kinds of HARQ schemes in the context of short-packet transmissions with energy constraints. We derive optimal power allocation strategies and we show that a minimum 50% energy saving can be achieved after very few transmission attempts if we enable packet combining at the receiver side.