149 research outputs found

    THROUGHPUT IMPROVEMENT AND COMPARATIVE PERFORMANCE ANALYSIS OF INTEGRATED NETWORKS

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    The demand for high-speed communication continue to increase significantly. Industry forecasts have shown that future data services would contribute to rapid growth in data traffic, with most of this traffic primarily indoors and at hotspots locations. Thus, the deployment and integration of small cell base stations (SCBSs) with Wireless Local Area Network (WLAN) or Wi-Fi is viewed as a critical solution to offload traffic, maximize coverage and boost future wireless systems capacity. This thesis reviews the existing network of WLAN, Long Term Evolution (LTE) and Worldwide Interoperability for Microwave Access (WiMAX). Tight and Loosely coupled integration of these networks is studied. More specifically, the introduction of small cell (SC) in loosely coupled Wi-Fi /WiMAX and Wi-Fi/LTE are proposed. These designs are tested in real-time user experience applications consisting of video conferencing, hypertext transfer protocol (HTTP) and email using industrial simulation software, Riverbed Modeler 18.7. Quality of service parameters was used to analyze these networks. It was found that the throughput of loosely coupled Wi-Fi/WiMAX network can be optimized by small cell. The loosely coupled architecture of Wi-Fi/WiMAX small cell outperforms that of Wi-Fi/LTE small cell. The loosely coupled independently deployed network of Wi-Fi/LTE small cell performs better than the Wi-Fi network. The Wi-Fi/LTE small cell network achieved a substantial rise in downlink throughput in a network consisting of only video conferencing subscriber station

    Suitability of NB-IoT for indoor industrial environment: a survey and insights

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    The Internet of Things (IoT) and its applications in industrial settings are set to bring in the fourth industrial revolution. The industrial environment consisting of high profile manufacturing plants and a variety of equipment is inherently characterized by high reflectiveness, causing significant multi-path components that affect the propagation of wireless communicationsโ€”a challenge among others that needs to be resolved. This paper provides a detailed insight into Narrow-Band IoT (NB-IoT), Industrial IoT (IIoT), and Wireless Sensor Networks (WSN) within the context of indoor industrial environments. It presents the applications of NB-IoT for industrial settings, such as the challenges associated with these applications. Furthermore, future research directions were put forth in the areas of NB-IoT network management using self-organizing network (SON) technology, edge computing for scalability enhancement, security in NB-IoT generated data, and proposing a suitable propagation model for reliable wireless communications

    ์ด๊ธฐ์ข… IoT ๊ธฐ๊ธฐ๊ฐ„ ํ˜‘๋ ฅ์„ ํ†ตํ•œ ๋„คํŠธ์›Œํฌ ์„ฑ๋Šฅ ํ–ฅ์ƒ

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    ํ•™์œ„๋…ผ๋ฌธ(๋ฐ•์‚ฌ) -- ์„œ์šธ๋Œ€ํ•™๊ต๋Œ€ํ•™์› : ๊ณต๊ณผ๋Œ€ํ•™ ์ „๊ธฐยท์ •๋ณด๊ณตํ•™๋ถ€, 2022. 8. ๋ฐ•์„ธ์›….The Internet of Things (IoT) has become a daily life by pioneering applications in various fields. In this dissertation, we consider increasing transmission data rate with energy efficiency, extending transmission coverage with low power, and improving reliability in congested frequency bands as three challenges to expanding IoT applications. We address two issues to overcome these challenges. First, we design a layered network system with a new structure that combines Bluetooth Low Energy (BLE) and Wi-Fi networks in a multi-hop network. Based on the system, we propose methods to increase data rate with energy efficiency and extend transmission coverage in a low-power situation. We implement the proposed system in the Linux kernel and evaluate the performance through an indoor testbed. As a result, we confirmed that the proposed system supports high data traffic and reduces average power consumption in the testbed compared to the existing single BLE/Wi-Fi ad-hoc network in a multi-hop situation. Second, we tackle the adaptive frequency hopping (AFH) problem of BLE through cross-technology communication (CTC) and channel weighting. We design the AFH scheme that weights the channels used by BLE devices with improving reliability in the congested bands of both Wi-Fi and BLE devices. We evaluate the proposed scheme through prototype experiments and simulations, confirming that the proposed scheme increases the packet reception rate of BLE in the congested ISM band compared to the existing AFH algorithm.์‚ฌ๋ฌผ์ธํ„ฐ๋„ท์€ ํ˜„์žฌ ๋‹ค์–‘ํ•œ ์˜์—ญ์—์„œ application์„ ๊ฐœ์ฒ™ํ•˜์—ฌ ์ƒํ™œํ™”๋˜์–ด ์™”๋‹ค. ์ด ํ•™์œ„ ๋…ผ๋ฌธ์—์„œ๋Š” ์‚ฌ๋ฌผ์ธํ„ฐ๋„ท์˜ ์‘์šฉ ์‚ฌ๋ก€ ํ™•์žฅ์„ ์œ„ํ•ด ์—๋„ˆ์ง€ ํšจ์œจ์ ์ธ ์ „์†ก ์†๋„ ํ–ฅ์ƒ, ์ €์ „๋ ฅ ์ƒํ™ฉ์—์„œ์˜ ์ „์†ก ๋ฒ”์œ„ ํ™•์žฅ, ํ˜ผ์žกํ•œ ๋Œ€์—ญ์—์„œ์˜ ์‹ ๋ขฐ์„ฑ ํ–ฅ์ƒ์„ ์ƒˆ๋กœ์šด ๋„์ „ ๊ณผ์ œ๋กœ ์‚ผ๊ณ , ์ด๋Ÿฌํ•œ ๋„์ „ ๊ณผ์ œ๋ฅผ ๊ทน๋ณตํ•  ๋‘ ๊ฐ€์ง€ ์ฃผ์ œ๋ฅผ ๋‹ค๋ฃฌ๋‹ค. ์ฒซ์งธ, ๋‹ค์ค‘ ํ™‰ ๋„คํŠธ์›Œํฌ ์ƒํ™ฉ์—์„œ์˜ ๋ธ”๋ฃจํˆฌ์Šค ์ €์ „๋ ฅ๊ณผ Wi-Fi ๋„คํŠธ์›Œํฌ๋ฅผ ๊ฒฐํ•ฉ ํ•œ ์ƒˆ๋กœ์šด ๊ตฌ์กฐ์˜ ๊ณ„์ธต์  ๋„คํŠธ์›Œํฌ ์‹œ์Šคํ…œ์„ ์„ค๊ณ„ํ•˜๊ณ  ์ด์— ๊ธฐ๋ฐ˜ํ•œ ์—๋„ˆ์ง€ ํšจ์œจ์ ์ธ ์ „์†ก ์†๋„ ํ–ฅ์ƒ ๋ฐ ์ €์ „๋ ฅ ์ƒํ™ฉ์—์„œ์˜ ์ „์†ก ๋ฒ”์œ„ํ™•์žฅ์„ ์ œ์•ˆํ•œ๋‹ค. ์ œ์•ˆ๋œ ์‹œ์Šคํ…œ์€ Linux ์ปค๋„์— ๊ตฌํ˜„ํ•˜์—ฌ ์‹ค๋‚ด ํ…Œ์ŠคํŠธ๋ฒ ๋“œ๋ฅผ ํ†ตํ•ด ์„ฑ๋Šฅ์„ ํ‰๊ฐ€ํ•œ๋‹ค. ๊ฒฐ๊ณผ์ ์œผ๋กœ ์ œ์•ˆ ํ•œ ๊ธฐ๋ฒ•์ด ๋‹ค์ค‘ ํ™‰ ์ƒํ™ฉ์—์„œ ๊ธฐ์กด ๋ธ”๋ฃจํˆฌ์Šค ์ €์ „๋ ฅ/Wi-Fi ๋‹จ์ผ ad-hoc ๋„คํŠธ์›Œํฌ์™€ ๋น„๊ตํ•˜์—ฌ ๋†’์€ ๋ฐ์ดํ„ฐ ํŠธ๋ž˜ํ”ฝ์„ ์ง€์›ํ•˜๋ฉฐ, ํ…Œ์ŠคํŠธ๋ฒ ๋“œ์—์„œ์˜ ํ‰๊ท  ์ „๋ ฅ ์†Œ๋น„๋ฅผ ์ค„ ์ด๋Š” ๊ฒƒ์„ ํ™•์ธํ•œ๋‹ค. ๋‘˜์งธ, Cross-technology Communication (CTC)๊ณผ ์ฑ„๋„ ๊ฐ€์ค‘์น˜๋ฅผ ํ†ตํ•œ ๋ธ”๋ฃจํˆฌ์Šค ์ €์ „๋ ฅ์˜ Adaptive Frequency Hopping (AFH) ๋ฌธ์ œ๋ฅผ ํ•ด๊ฒฐํ•œ๋‹ค. ์ตœ์ข…์ ์œผ๋กœ ๋ธ”๋ฃจํˆฌ์Šค ์ €์ „๋ ฅ ๊ธฐ๊ธฐ๊ฐ€ ์‚ฌ์šฉํ•˜๋Š” ์ฑ„๋„์— ๊ฐ€์ค‘์น˜๋ฅผ ๋‘๋Š” AFH ๊ธฐ๋ฒ•์„ ์„ค๊ณ„ํ•˜์—ฌ Wi-Fi ์™€ ๋ธ”๋ฃจํˆฌ์Šค ์ €์ „๋ ฅ ๊ธฐ๊ธฐ๊ฐ€ ๋ชจ๋‘ ํ˜ผ์žกํ•œ ๋Œ€์—ญ์—์„œ์˜ ์‹ ๋ขฐ์„ฑ์„ ํ–ฅ์ƒํ•œ๋‹ค. ํ”„๋กœํ† ํƒ€์ž… ์‹คํ—˜๊ณผ ์‹œ๋ฎฌ๋ ˆ์ด์…˜์„ ํ†ตํ•ด ์ œ์•ˆํ•œ ๊ธฐ๋ฒ•์ด ๊ธฐ์กด์˜ AFH ๊ธฐ๋ฒ•๊ณผ ๋น„๊ตํ•˜์—ฌ ํ˜ผ์žกํ•œ ISM ๋Œ€์—ญ์—์„œ ๋ธ”๋ฃจํˆฌ์Šค ์ €์ „๋ ฅ์˜ ํŒจํ‚ท ์ˆ˜์‹ ์œจ์„ ์ฆ๊ฐ€์‹œํ‚ค๋Š” ๊ฒƒ์„ ํ™•์ธํ•œ๋‹ค.1 Introduction 1 1.1 Motivation 1 1.2 Contributions and Outline 2 2 Wi-BLE: On Cooperative Operation of Wi-Fi and Bluetooth Low Energy under IPv6 4 2.1 Introduction 4 2.2 Related Work 7 2.2.1 Multihop Connectivity for Wi-Fi or BLE 7 2.2.2 Multi-radio Operation 11 2.3 System Overview 13 2.3.1 Control Plane 13 2.3.2 Data Plane 16 2.3.3 Overall Procedure 16 2.4 MABLE: AODV Routing over BLE 17 2.4.1 BLE Channel Utilization 17 2.4.2 Joint Establishment of Route and Connection 20 2.4.3 Link Quality Metric for BLE Data Channels 22 2.4.4 Bi-directional Route Error Propagation 25 2.5 Wi-BLE: Wi-Fi Ad-hoc over BLE 27 2.5.1 Radio Selection 27 2.5.2 Routing and Radio Wake-up for Wi-Fi 30 2.6 Evaluation 32 2.6.1 BLE Routing 33 2.6.2 Wi-Fi Routing over BLE 35 2.6.3 Radio Selection 38 2.7 Summary 40 3 WBC-AFH: Direct Wi-Fi to BLE Communication based AFH 41 3.1 Introduction 41 3.2 Background 45 3.2.1 Frequency hopping in BLE 45 3.2.2 Cross Technology Communication 47 3.3 Proposed AFH 49 3.3.1 CTC based informing 50 3.3.2 Weighted channel select 51 3.3.3 Hopping set size optimization 52 3.3.4 WBC-AFH 54 3.4 Evaluation 57 3.4.1 Setup 57 3.4.2 Robustness 60 3.4.3 Reliability 61 3.5 Future Work 65 3.6 Summary 66 4 Conclusion 67๋ฐ•

    Performance Modeling and Analysis of Wireless Local Area Networks with Bursty Traffic

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    The explosive increase in the use of mobile digital devices has posed great challenges in the design and implementation of Wireless Local Area Networks (WLANs). Ever-increasing demands for high-speed and ubiquitous digital communication have made WLANs an essential feature of everyday life. With audio and video forming the highest percentage of traffic generated by multimedia applications, a huge demand is placed for high speed WLANs that provide high Quality-of-Service (QoS) and can satisfy end userโ€™s needs at a relatively low cost. Providing video and audio contents to end users at a satisfactory level with various channel quality and current battery capacities requires thorough studies on the properties of such traffic. In this regard, Medium Access Control (MAC) protocol of the 802.11 standard plays a vital role in the management and coordination of shared channel access and data transmission. Therefore, this research focuses on developing new efficient analytical models that evaluate the performance of WLANs and the MAC protocol in the presence of bursty, correlated and heterogeneous multimedia traffic using Batch Markovian Arrival Process (BMAP). BMAP can model the correlation between different packet size distributions and traffic rates while accurately modelling aggregated traffic which often possesses negative statistical properties. The research starts with developing an accurate traffic generator using BMAP to capture the existing correlations in multimedia traffics. For validation, the developed traffic generator is used as an arrival process to a queueing model and is analyzed based on average queue length and mean waiting time. The performance of BMAP/M/1 queue is studied under various number of states and maximum batch sizes of BMAP. The results clearly indicate that any increase in the number of states of the underlying Markov Chain of BMAP or maximum batch size, lead to higher burstiness and correlation of the arrival process, prompting the speed of the queue towards saturation. The developed traffic generator is then used to model traffic sources in IEEE 802.11 WLANs, measuring important QoS metrics of throughput, end-to-end delay, frame loss probability and energy consumption. Performance comparisons are conducted on WLANs under the influence of multimedia traffics modelled as BMAP, Markov Modulated Poisson Process and Poisson Process. The results clearly indicate that bursty traffics generated by BMAP demote network performance faster than other traffic sources under moderate to high loads. The model is also used to study WLANs with unsaturated, heterogeneous and bursty traffic sources. The effects of traffic load and network size on the performance of WLANs are investigated to demonstrate the importance of burstiness and heterogeneity of traffic on accurate evaluation of MAC protocol in wireless multimedia networks. The results of the thesis highlight the importance of taking into account the true characteristics of multimedia traffics for accurate evaluation of the MAC protocol in the design and analysis of wireless multimedia networks and technologies

    Practical large-scale coordinated scheduling in LTE-Advanced networks

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    In LTE-Advanced, the same spectrum can be re-used in neighboring cells, hence coordinated scheduling is employed to improve the overall network performance (cell throughput, fairness, and energy efficiency) by reducing inter-cell interference. In this paper, we advocate that large-scale coordination can be obtained through a layered solution: a cluster of few (i.e., three) cells is coordinated at the first level, and clusters of coordinated cells are then coordinated at a larger scale (e.g., tens of cells). We model both small-scale coordination and large-scale coordination as optimization problems, show that solving them at optimality is prohibitive, and propose two efficient heuristics that achieve good results, and yet are simple enough to be run at every Transmission Time Interval (TTI). Detailed packet-level simulations show that our layered approach outperforms the existing ones, both static and dynamic
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