Recent Developments on Mobile Ad-Hoc Networks and Vehicular Ad-Hoc Networks

This book presents collective works published in the recent Special Issue (SI) entitled "Recent Developments on Mobile Ad-Hoc Networks and Vehicular Ad-Hoc Networks”. These works expose the readership to the latest solutions and techniques for MANETs and VANETs. They cover interesting topics such as power-aware optimization solutions for MANETs, data dissemination in VANETs, adaptive multi-hop broadcast schemes for VANETs, multi-metric routing protocols for VANETs, and incentive mechanisms to encourage the distribution of information in VANETs. The book demonstrates pioneering work in these fields, investigates novel solutions and methods, and discusses future trends in these field

Cross-layer design for network performance optimization in wireless networks

In this dissertation, I use mathematical optimization approach to solve the complex network problems. Paper l and paper 2 first show that ignoring the bandwidth constraint can lead to infeasible routing solutions. A sufficient condition on link bandwidth is proposed that makes a routing solution feasible, and then a mathematical optimization model based on this sufficient condition is provided. Simulation results show that joint optimization models can provide more feasible routing solutions and provide significant improvement on throughput and lifetime. In paper 3 and paper 4, an interference model is proposed and a transmission scheduling scheme is presented to minimize the end-to-end delay. This scheduling scheme is designed based on integer linear programming and involves interference modeling. Using this schedule, there are no conflicting transmissions at any time. Through simulation, it shows that the proposed link scheduling scheme can significantly reduce end-to-end latency. Since to compute the maximum throughput is an NP-hard problem, efficient heuristics are presented in Paper 5 that use sufficient conditions instead of the computationally-expensive-to-get optimal condition to capture the mutual conflict relation in a collision domain. Both one-way transmission and two-way transmission are considered. Simulation results show that the proposed algorithms improve network throughput and reduce energy consumption, with significant improvement over previous work on both aspects. Paper 6 studies the complicated tradeoff relation among multiple factors that affect the sensor network lifetime and proposes an adaptive multi-hop clustering algorithm. It realizes the best tradeoff among multiple factors and outperforms others that do not. It is adaptive in the sense the clustering topology changes over time in order to have the maximum lifetime --Abstract, page iv

A review of routing protocols in wireless body area networks

Recent technological advancements in wireless communication, integrated circuits and Micro-Electro-Mechanical Systems (MEMs) has enabled miniaturized, low-power, intelligent, invasive/ non-invasive micro and nano-technology sensor nodes placed in or on the human body for use in monitoring body function and its immediate environment referred to as Body Area Networks (BANs). BANs face many stringent requirements in terms of delay, power, temperature and network lifetime which need to be taken into serious consideration in the design of different protocols. Since routing protocols play an important role in the overall system performance in terms of delay, power consumption, temperature and so on, a thorough study on existing routing protocols in BANs is necessary. Also, the specific challenges of BANs necessitates the design of new routing protocols specifically designed for BANs. This paper provides a survey of existing routing protocols mainly proposed for BANs. These protocols are further classified into five main categories namely, temperature based, cross-layer, cluster based, cost-effective and QoS-based routing, where each protocol is described under its specified category. Also, comparison among routing protocols in each category is given. © 2013 ACADEMY PUBLISHER

이기종 IoT 기기간 협력을 통한 네트워크 성능 향상

학위논문(박사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2022. 8. 박세웅.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.사물인터넷은 현재 다양한 영역에서 application을 개척하여 생활화되어 왔다. 이 학위 논문에서는 사물인터넷의 응용 사례 확장을 위해 에너지 효율적인 전송 속도 향상, 저전력 상황에서의 전송 범위 확장, 혼잡한 대역에서의 신뢰성 향상을 새로운 도전 과제로 삼고, 이러한 도전 과제를 극복할 두 가지 주제를 다룬다. 첫째, 다중 홉 네트워크 상황에서의 블루투스 저전력과 Wi-Fi 네트워크를 결합 한 새로운 구조의 계층적 네트워크 시스템을 설계하고 이에 기반한 에너지 효율적인 전송 속도 향상 및 저전력 상황에서의 전송 범위확장을 제안한다. 제안된 시스템은 Linux 커널에 구현하여 실내 테스트베드를 통해 성능을 평가한다. 결과적으로 제안 한 기법이 다중 홉 상황에서 기존 블루투스 저전력/Wi-Fi 단일 ad-hoc 네트워크와 비교하여 높은 데이터 트래픽을 지원하며, 테스트베드에서의 평균 전력 소비를 줄 이는 것을 확인한다. 둘째, Cross-technology Communication (CTC)과 채널 가중치를 통한 블루투스 저전력의 Adaptive Frequency Hopping (AFH) 문제를 해결한다. 최종적으로 블루투스 저전력 기기가 사용하는 채널에 가중치를 두는 AFH 기법을 설계하여 Wi-Fi 와 블루투스 저전력 기기가 모두 혼잡한 대역에서의 신뢰성을 향상한다. 프로토타입 실험과 시뮬레이션을 통해 제안한 기법이 기존의 AFH 기법과 비교하여 혼잡한 ISM 대역에서 블루투스 저전력의 패킷 수신율을 증가시키는 것을 확인한다.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 67박

Optimization and Learning in Energy Efficient Cognitive Radio System

Energy efficiency and spectrum efficiency are two biggest concerns for wireless communication. The constrained power supply is always a bottleneck to the modern mobility communication system. Meanwhile, spectrum resource is extremely limited but seriously underutilized. Cognitive radio (CR) as a promising approach could alleviate the spectrum underutilization and increase the quality of service. In contrast to traditional wireless communication systems, a distinguishing feature of cognitive radio systems is that the cognitive radios, which are typically equipped with powerful computation machinery, are capable of sensing the spectrum environment and making intelligent decisions. Moreover, the cognitive radio systems differ from traditional wireless systems that they can adapt their operating parameters, i.e. transmission power, channel, modulation according to the surrounding radio environment to explore the opportunity. In this dissertation, the study is focused on the optimization and learning of energy efficiency in the cognitive radio system, which can be considered to better utilize both the energy and spectrum resources. Firstly, drowsy transmission, which produces optimized idle period patterns and selects the best sleep mode for each idle period between two packet transmissions through joint power management and transmission power control/rate selection, is introduced to cognitive radio transmitter. Both the optimal solution by dynamic programming and flexible solution by reinforcement learning are provided. Secondly, when cognitive radio system is benefited from the theoretically infinite but unsteady harvested energy, an innovative and flexible control framework mainly based on model predictive control is designed. The solution to combat the problems, such as the inaccurate model and myopic control policy introduced by MPC, is given. Last, after study the optimization problem for point-to-point communication, multi-objective reinforcement learning is applied to the cognitive radio network, an adaptable routing algorithm is proposed and implemented. Epidemic propagation is studied to further understand the learning process in the cognitive radio network