Throughput of distributed queueing-based LoRa for long-distance communication

LoRa, due to its advantage of long-range communication capability, is promising for Internet of Things (IoT) and space-air-ground communications. However, the conventional MAC protocol used with LoRa is classified as an Aloha-based algorithm, which leads to drastic decrease in throughput when a huge amount of end-devices try to access the network. To achieve stable and high throughput of LoRa, we propose a design to combine the distributed queueing (DQ) and in-band-full-duplex (IBFD) technologies. The usage of DQ mechanism is benefit for fast collision resolution, while the IBFD-enabled gateway helps to reduce the heavy control overhead of DQ. The designs of access procedure and frame structure are discussed in detail. The outage probability and average throughput are evaluated under imperfect self-interference cancelation. Also, a mathematical programming method is developed to optimize the spreading factor and code rate. Numerical results show that our proposal gains an extra enhancement of 1.83-fold in throughput.

Throughput of Distributed Queueing Based LoRa for Long-Distance Communication

LoRa, due to its advantage of long-range communication capability, is promising for Internet of Things (IoT) and space-air-ground communications. However, the conventional MAC protocol used with LoRa is classified as an Aloha-based algorithm, which leads to drastic decrease in throughput when a huge amount of end-devices try to access the network. To achieve stable and high throughput of LoRa, we propose a design to combine the distributed queueing (DQ) and in-band-full-duplex (IBFD) technologies. The usage of DQ mechanism is benefit for fast collision resolution, while the IBFD-enabled gateway helps to reduce the heavy-control-overhead of DQ. The designs of access procedure and frame structure are discussed in detail. The outage probability and average throughput are evaluated under imperfect self-interference cancellation. Also, a mathematical programming method is developed to optimize the spreading-factor and code-rate. Numerical results show that our proposal gains an extra enhancement of 1.83-fold in throughput.

A Fuzzy-MOP-Based Competence Set Expansion Method for Technology Roadmap Definitions

Technology roadmaps have been widely adopted as an important management tool during the past three decades after their invention by Motorola in the 1980s. Technology roadmapping processes can be integrated with a firm’s competence sets and play dominant roles in strategy definitions. Although the issue of how multiple objectives can be dealt with in technology roadmaps by including the uncertainties of the modern management environment is important, it has seldom been addressed. To remedy this, we aim in this research to propose a competence set expansion method based on fuzzy multiple objective programming (FMOP). An empirical study based on the roadmapping of silicon intellectual properties (SIPs) of automotive applications will be used to demonstrate the feasibility of the proposed roadmapping method. In the future, the proposed analytic technique can be integrated with the data mining results of academic research database, patent libraries, etc. The well-verified mathematical programming method can serve as a basis for research and development (R&D) strategy definitions by managers of high-technology firms as well as policy makers of governments.

Design of total water networks of multiple properties based on operator potential concepts and an iterative procedure

The design of property-based total water networks by using the concepts of operator potential is investigated with an iterative approach. The precedence order of demands is identified with the operator potential values of demands. The internal sources to be regenerated are selected based on the values of operator potential of sources. A linear programming approach is used to determine the allocation of sources to demands. With the proposed method, the networks which meet both the requirements of demands and environmental regulations can be obtained. Two examples are studied to illustrate the proposed method. It is shown that the results obtained by this work are comparable to that obtained by mathematical programming method in the literature. For Example 1, flowrate of regenerated stream is reduced 28.5% compared to that in the literature results with almost the same freshwater consumption. In addition, the number of interconnections for this work is smaller than that of literature, which means that the design structure of this work is simpler. For Example 2, freshwater consumption is reduced by 4.29% with almost the same regeneration flowrate. However, the number of interconnections for this work is 24, which is higher than 23, that is the value of the literature result. Compared to graphical methods, the method proposed in this paper can handle the networks with more than three properties. Compared to mathematical programming methods, the proposed method has clear engineering meaning.

ANALYSIS OF PRIORITY QUEUES WITH PENTAGON FUZZY NUMBER

Fuzziness is a sort of recent incoherence. Fuzzy set theory is asserted to depict vagueness. This study explores the queuing model of priority classes adopting pentagon fuzzy number with the inclusions of fuzzy set operations. A mathematical programming method is designed to establish the membership function of the system performance, in which the arrival rate and service rate of the system performance of two priority classes are utilized as fuzzy numbers. Based on  -cut approach and Zadeh’s extension principle, the fuzzy queues are scaled down to a family of ordinary queues. The potency of the performance measures of the characteristics of the queuing model is ensured with an illustration and its graph.