Wired-wireless Networks Research Articles

End-to-End No-wait Scheduling for Time-Triggered Streams in Mixed Wired-Wireless Networks

Proprietary communication technologies for time-critical communication in industrial environments are being gradually replaced by Time-sensitive Networking (TSN)-enabled Ethernet. Furthermore, attempts have been made to bring TSN features into wireless networks so that the flexibility of wireless networks can be utilized, and the end-to-end timings for Time-Triggered (TT) streams can be guaranteed. Given a mixed wired-wireless network, the scheduling problem should be solved for a set of TT stream requests. In this paper, we formulate the no-wait scheduling problem for mixed wired-wireless networks as a Mixed Integer Linear Programming (MILP) model with the objective of minimizing the flowspan. We also propose a relaxation of the original MILP in the form of a 2-stage MILP formulation. Next, a scalable approach based on the greedy heuristic is proposed to solve the problem for realistic-size networks. Evaluation results show that the greedy heuristic is suitable for realistic problem sizes where the MILP-based approach is found to be practically infeasible. Furthermore, the impact of wireless requests on the performance of the greedy heuristic is reported.

Adaptively Encoding Multimode VCSEL with Spectral Efficient Data Formats for Seamless Wired-Wireless Network Coverage

Adaptively Encoding Multimode VCSEL with Spectral Efficient Data Formats for Seamless Wired-Wireless Network Coverage

Comparative Analysis of Network Parameters using Noxim Simulator

In the field of Network-on-Chip, simulation is one of the primary techniques used to examine and evaluate novel ideas. It is necessary to have simulation tools available that are frequently restricted to modelling particular network configurations in order to evaluate the performance and power figures of NoC and WiNoC systems. This article introduces Noxim, a SystemC-developed open, extendible, customizable, cycle-accurate NoC simulator that enables the analysis of the performance and power statistics of both established wired NoC and new WiNoC designs. The Noxim simulator stands out among the many simulators that can be discovered in the literature. A lot of scholars use it since it supports wifi and is open-source. Hybrid wired-wireless networks aim to combine the finest aspects of the two strategies. In this study, investigation on various optimal configurations are carried out considering various test scenarios. Different parameters like Throughput, delivered packets, delay, and battery consumption and Packet Injection Rate are considered for optimisation. The findings demonstrate that the test cases utilised only require a small number of wireless routers, enhancing the metrics desired.

Hardware Efficient Clock Synchronization Across Wi-Fi and Ethernet-Based Network Using PTP

Precision time protocol (PTP), a state-of-the-art clock synchronization protocol primarily designed for wired networks, has recently gained attention in the wireless community, due to the increased use of the IEEE 802.11 wireless local area networks (WLAN) in real-time distributed systems. However, all the existing WLAN-based PTP designs either incorporate software timestamping (TS) delivering poor clock synchronization accuracy, or hardware (HW) TS providing better synchronization accuracy at the cost of a significant amount of HW overhead. Moreover, the performance of the existing PTP solutions is mostly evaluated in single-hop wireless networks, while the performance across wired and wireless networks is taken for granted. In this article, a new software-defined-radio-based approach to implement PTP is introduced and validated for the IEEE 802.11 WLAN. Instead of using a dedicated HW clock, the solution utilizes the timing synchronization function clock, an existing clock in the IEEE802.11 standard for synchronization between access point and WLAN stations. The performance of the proposed solution is first investigated within a single-hop WLAN and then across wired–wireless networks. Experimental results unveil that 90% of the absolute clock synchronization error falls within 1.4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu \mathrm{s}$</tex-math></inline-formula> .

Coded Caching Over Multicast Routing Networks

The coded caching scheme originally proposed by Maddah-Ali and Niesen (MAN) transmits coded multicast messages from a server to users equipped with caches via a capacitated shared-link and was shown to be information theoretically optimal within a constant multiplicative factor. This work extends the MAN scheme to a class of two-hop wired-wireless networks including one server connected via fronthaul links to a layer of H helper nodes (access points/base stations), which in turn communicate via a wireless access network to K users, each equipped with its own cache. Two variants are considered, which differ in the modeling of the access segment. Both models should be regarded as abstractions at the “network layer” for physical scenarios such as local area networks and cellular networks, spatially distributed over a certain coverage area. The key of our approach consists of routing MAN-type multicast messages through the network and formulating the optimal routing scheme as an optimization problem that can be solved exactly or for which we give powerful heuristic algorithms. Our approach addresses at once many of the open practical problems identified as stumbling blocks for the application of coded caching in practical scenarios, namely: asynchronous streaming sessions, finite file size, scalability of the scheme to large and spatially distributed networks, user mobility and random activity (users joining and leaving the system at arbitrary times), decentralized prefetching of the cache contents, end-to-end encryption of HTTPS requests, which renders the helper nodes oblivious of the users' demands.

Hybrid wired-wireless communication networks for factory automation

Abstract This thesis investigates a wireless communication network that is suitable to be deployed as a transparent intermediate wireless network within a hybrid wired-wireless network serving industrial applications with strict timing and reliability requirements. Physical layer and medium access scheme are in focus.

Congestion avoidance algorithm using ARIMA(2,1,1) model-based RTT estimation and RSS in heterogeneous wired-wireless networks

In the past two decades, there has been a fast growth in the heterogeneous wired-wireless network which connects variety of networks such as wired network, wireless network, high speed network and sensor network with the Internet. Since the wired network and wireless network use the different technologies, there is a necessity of developing new protocols or redesigning of existing protocols. Transmission Control Protocol is redesigned to achieve the reliable and effective communication in the heterogeneous wired-wireless network. The basic assumption made in Transmission Control Protocol is that the packet losses are caused by the network congestion but in case of wireless network, the packet losses may be due to temporary link failure, high Bit-Error-Rate etc. Hence the congestion avoidance algorithm of Transmission Control Protocol needs to be redesigned to cope with heterogeneous wired-wireless network. Therefore in this paper, we propose a congestion avoidance algorithm which differentiates the cause of packet losses. The essential components of proposed algorithm are round-trip-time estimation, backlogged packet estimation, channel status notification, loss differentiation algorithm and congestion window control. A round-trip-time estimation using ARIMA(2,1,1) model is proposed in this paper which estimates the sudden changes in the round trip time. It helps us to estimate the backlogged packet and thereby differentiating the congestive packet loss from non-congestive packet loss. In addition, we use the received signal strength of wireless receiver to differentiate the packet losses. Based on the packet loss differentiation, the congestion window size is controlled to avoid the congestion in the network. The proposed algorithm is simulated using network simulator under different network environments. From the simulation results, it is realized that the proposed congestion avoidance algorithm performs well in the heterogeneous wired-wireless network.

Distributed event-triggered hybrid wired-wireless networked control with $${H_2}/{H_\infty }$$ H 2 / H ∞ filtering

Aiming at the fact that distributed multi-channel hybrid network-induced delays and noise interference may deteriorate the control performance of hybrid networked control systems, distributed event-triggered hybrid wired-wireless networked control with \({H_2}/{H_\infty }\) filtering is proposed. A distributed event-triggered mechanism is firstly employed to reduce communication burden, and two Markov chains are used to respectively describe different characters of network-induced delays of hybrid wired-wireless networks. Then, a \({H_2}/{H_\infty }\) filter is employed to improve the input signal precision of the controller, where a general closed-feedback filtering and control system model with distributed event-triggered parameters and network-induced delays of hybrid wired-wireless networks is proposed. Furthermore, the designed filter and controller enable the closed-feedback filtering and control system to be stochastic stability and to achieve a prescribed \({H_2}/{H_\infty }\) performance, and the relationships between the stability criteria and the maximum network-induced delays, distributed event-triggered parameters, the filter and controller parameters and the system performance parameter are established. Finally, simulation results confirm the effectiveness of the proposed method.

Mixed time/event-triggered distributed predictive control over wired-wireless networks

Communicating via mixed wired-wireless connections is the development trend for large-scale distributed control systems. In this communication environment, due to the limited wireless resources, the communication patterns of subsystems have changed fundamentally, and the design of time-triggered and event-triggered distributed controllers should be taken into account simultaneously. The objective of this paper is to investigate mixed time/event-triggered dual-mode distributed predictive control (DPC) for constrained large-scale linear systems subject to bounded disturbances. Considering the effects of two different communication modes and introducing a prediction error between the current actual state and predicted state, the event-triggering condition is derived for each event-triggered subsystem. Based on this, a mixed time/event-triggered dual-mode DPC algorithm is proposed in view of the asynchronous coordination among subsystems. Furthermore, the sufficient conditions to ensure the recursive feasibility and closed-loop stability of mixed triggered DPC are developed. Finally, a multi-vehicle control system is provided to verify the effectiveness of the proposed approach.

Quantized control of distributed event-triggered networked control systems with hybrid wired–wireless networks communication constraints

Traditional analysis and design for networked control systems (NCSs) with state quantization have been investigated under single wired/wireless network environment. This paper studies the quantized control of distributed event-triggered NCSs under hybrid wired–wireless networks environment. Unlike the most existing NCSs, the controller communicates with distributed sensors through multiple wired–wireless channels and the measured signals from sensors might suffer from communication constraints of hybrid wired–wireless networks, which makes the quantized control of distributed event-triggered NCSs more complex. To reduce the communication burden of each channel, a distributed event-triggered mechanism and multiple quantization scheme are firstly proposed. The communication characters of hybrid wired–wireless networks are then analyzed, which are described by different Markov chains. Furthermore, a novel system model is presented, and a sufficient condition of the stochastic stability is derived. The relationship between the system stability criteria and the maximum hybrid wired–wireless network-induced delays, the event-generators parameters and multiple quantization parameters is established. Finally, simulation results confirm the effectiveness and feasibility of the proposed method.

Migrating Unfairness among Subflows in MPTCP with Network Coding for Wired-Wireless Networks

Recently, two new technologies have been introduced into the transport layer. One is network coding, and the other is multipath transmission control protocol (MPTCP). Network coding is introduced into the transport layer to enhance the performance of transmission control protocol (TCP) in wireless networks. Benefiting from multi-interface devices, MPTCP is proposed to make full use of the network resource. Theoretically, combining these two technologies can utilize resources more adequately. However, network coding and multipath transportation cannot collaborate well with each other because network coding invalidates the load-balancing feature of MPTCP congestion control schemes. In this paper, we first discuss the unfair congestion control issue in MPTCP combined with network coding (MPTCP/NC). Then, a new end-to-end congestion control solution, named Couple+, is presented to deal with the unfairness among subflows. In Couple+, sender tries to slightly slow down sending rate if the reason of packet loss is not decided. After judging of packet loss reason based on the characteristics of packet loss events, the rate will be recovered soon if the loss is caused by wireless error (wireless noise or collision) or be further reduced if the loss is caused by congestion. By simulation, we compare the performances of Couple+ and the previous congestion control scheme of MPTCP. The performance analysis proves that unfairness among subflows indeed exists, and our scheme can balance congestion among coded and noncoded subflows and can stay friendly with TCP flow.

Multiple event-triggered H2/H∞ filtering for hybrid wired–wireless networked systems with random network-induced delays

Unlike the widely existing H2/H∞ filtering methods under single (i.e., wired or wireless) network with single channel environment, there exist multiple event-generators and different network-induced delays in hybrid wired–wireless networks, which make H2/H∞ filtering analysis and design more complex. The main objective of this paper is to investigate multiple event-triggered H2/H∞ filtering for hybrid wired–wireless networked systems with random network-induced delays. For multi-sensor network communications, a multiple event-triggered mechanism is employed firstly, which can reduce communication burden of each channel. The different communication characters of hybrid wired–wireless networks are then described by two Markov chains, and a general filtering error dynamic system model with the event-triggered parameters and multi-channel network-induced delays of hybrid wired–wireless networks is presented. Furthermore, the designed filter enables the filtering error dynamic system to be stochastic stability and to achieve a prescribed performance, and the relationships between the stability criteria and the maximum network-induced delays of hybrid wired–wireless networks, the event-triggered parameters and the system performance parameter are established. Finally, simulation results confirm the effectiveness of the proposed method.

군 함정 문자 교신 지원을 위한 규칙 기반 엔진 설계

IT 기술의 발달은 컴퓨터를 이용하여 상호간에 정보를 주고 받으며 작전을 지휘하는 등 군 작전에 있어서 많은 변화를 가져왔다. 특히 해군의 경우 암호화된 유 무선망을 통해 실시간으로 이루어지는 문자 교신을 작전 훈련에 활용하고 있다. 하지만 이는 단순한 정보 교환에만 이용되고 있으며 실제 작전 훈련에 필요한 정보(교범, 지침서 등)의 내용은 필요할 때마다 찾아보고 있는 실정이다. 이에 따라 본 논문에서는 ECA 규칙을 문자 교신과 연동시켜 실시간으로 필요한 정보를 제공할 수 있는 규칙 기반 엔진을 설계하였으며 가상 시나리오 적용을 통해 이를 검증한 결과 83%의 정확율을 보였다. The development of IT technology has brought many changes in military operations. For example, the way of transmitting and receiving information from one another has changed. Partiicularly, in the case of the ROK Navy, they utilize encrypted real-time chattig over wire wireless network in operations and tranings. However, text communication is being utilized more in exanging of simple informations, and not for the partical informations required in the operations and exercises, doctrines and guidebooks are still being used in these cases. Therefore, I have designed a rule-based engine which can provide real-time informations by linking ECA rules to text communication, and it has been verified by running virtual scenarios. As a rusult, this engine showed an accuracy of 83%.

M2M/IoT 서비스를 위한 지그비 기반의 Publish/Subscr ibe 시스템 구현

Recently, smart devices has been spreaded and the definition of RFID/USN(Radio Frequency Identification/Ubiquitous Sensor Network) technology has also extended. So, originally, human is an agent of communications but now, 'the things' are also an agent of communication. That is, Internet of Things(IoT). IoT is very big IT infra technology that is based on wire-wireless network technologies such as Bluetooth and Wi-Fi. However, in reality, IoT service that can provide various meaning and integrate smoothly is not appear yet. To solve these problems of IoT, we implemented Publish/Subscribe system, which operate in Zigbee based wireless sensor network by using MQTT-SN protocol. Moreover, this system can operate with combining MQTT system that is already existed in external Internet network so, extensibility and flexibility aspect is excellent. We show that possibility of IoT services that is combined between different heterogeneous network through the MQTT-SN.

Method to enhance traffic capacity for two-layer complex networks

The study of traffic dynamics on multilayered networks is a hot issue, where the network topology is composed of two layers of subnetworks, such as wired–wireless networks and peer-to-peer networks. Virtual links on the logical layer can be changed or constructed easily, and therefore the topological structure of the upper logical layer can be efficiently constructed by a link removal strategy. In this paper, edges linking to nodes with large betweenness will be removed. The structure of the upper-layer network can be optimized freely based on our method. Simulation results show that for both shortest path routing strategy and efficient routing strategy, the traffic capacity of two-layer networks is significantly improved. In addition, the average transmission time of packets and the average path length are also investigated in this paper.

사물인터넷 보안 기술 연구

Abstract The on-going developments of networks and smart devices have been increasing people’s attraction to Internet of Things which connects individuals to objects and anything anytime anywhere. However, since the Internet of Things service gets accessed through wire-wireless networks, there have been always these various security threats occurring during the telecommunication process. In the light of that, this thesis looks into the security threat factors in relation to the Internet of Things service environment as well as both the security requirements and the security technologies and consequently proposes security strategies to assure safety of the Internet of Things service environment.

A multimedia transmission control algorithm based on cross-layer design in UMTS networks

The performance in the air interface of 3G/UMTS (Universal Mobile Telecommunications System) network is enhanced by the introduction of many advanced functionalities including ARQ (Automatic Repeat Request), HARQ (Hybrid ARQ) and AMC (Adaptive Modulation and Coding). Most existing TFRC (TCP-Friendly Rate Control)-based algorithms designed for wired-wireless heterogeneous networks fail to adapt to these advanced functionalities which results in degradation of performance. This paper proposes a novel cross-layer streaming transmission control algorithm WATC (Wireless-loss Aware Transmission Control) which makes use of the ARQ information to estimate the quality of wireless channels and improve the measurement of delay with the help of RLC (Radio Link Control) sublayer. WATC distinguishes wireless loss from congestion loss by the estimation of the quality of wireless channel and adjusts the sending rate according to the quality of wireless links and the tendency of delay variation. Simulation results show that WATC outperforms existing TFRC-like schemes in terms of loss rate control and throughput, while maintaining high throughput and fairness in multi-flow scenarios.

ECN-Based Congestion Probability Prediction over Hybrid Wired-Wireless Networks

Network congestions and wireless link errors are both potential reasons for packet losses in hybrid wired-wireless networks. Their coexistence necessitates the design of new mechanisms that can differentiate network states more precisely. In this paper, a method is proposed to distinguish between the two reasons of packet losses in hybrid wired-wireless networks (i.e., congestions and wireless link errors) and calculate the probability of network congestion in the former case. This method combines the information contained in CE bits of a sequence of ECN-enabled acknowledge packets to calculate the probability of network congestion; thus it is more accurate than methods using CE bits of a single acknowledge packet. Analysis on the effectiveness of the proposed method in calculating congestion probability is performed via simulations. The ability to differentiate precise network states helps a TCP source response to ECN feedback more adaptively. We discuss how to enhance existing TCP variants with the proposed method. Simulation results show that the enhanced TCP variants can effectively improve network performance.

BLOCK-LEVEL SUCCESS AND LOSS RUNS FOR STREAMING SERVICES OVER WIRED-WIRELESS NETWORKS

This paper considers the characteristics of block-level success and loss runs for streaming services over wired-wireless networks in which forward error correction (FEC) is employed for packet-loss resilience. We develop a single-server queueing model where the packet-transmission process over a wireless link is modeled by a Markovian service process (MSP) with two states Good and Bad. The queueing system has two input processes: a general renewal input process and a Poisson one. The former represents a streaming-packet flow, while the latter is for background traffic multiplexed at the queue. We investigate the dynamics of the system state during the interval from the arrival epoch of the first packet of the block to that of the last one, deriving the block-loss (resp. block-success) run distribution, i.e., the probability distribution of the number of consecutive block loss (resp. success). The analytical model is validated by trace-driven simulation experiments. Numerical examples show that when the traffic intensity is high, the moments of block-level loss and success runs are significantly affected by the volume of background traffic and the FEC redundancy, rather than the system capacity.

Active Scheme to Measure Throughput of Wireless Access Link in Hybrid Wired-Wireless Network

In this letter, we propose an active scheme to measure the download throughput of an IEEE 802.11 wireless access link in a hybrid wired-wireless network. The proposed scheme is based on sending pairs of probing packets to a wireless end host to determine the smallest and average intra-packet gaps of the probing packets that are used for the estimation of the constant dispersion gap that wireless access creates. We present experimental evaluations of the proposed scheme, and the obtained results show that the proposed scheme achieves high measurement accuracy. Furthermore, we show that the proposed scheme is able to work under the presence of cross traffic along the path.