The demand for low-cost wireless LAN deployment is increasing in indoor networks. However, in indoor environments, extending wireless LAN coverage across obstacles and complex layouts remains difficult. To address this issue, we aim to expand wireless LAN coverage by using the interior of metal pipes in buildings as radio-wave propagation paths. Since actual pipe systems often contain non-metallic sections, detailed performance evaluation under such mixed conditions is essential. This paper investigates communication performance in the presence of non-metallic segments through practical experiments using the IEEE 802.11 wireless standard, and discusses prospects for developing wireless network systems based on the results.

In 5G networks, users require high-quality services for a wide range of applications. However, conventional QoS control mechanisms do not reflect the quality actually experienced by end users in network management. This study proposes a stress-aware networking system for Beyond 5G environment utilizing user’s stress level data collected from wearable devices. This paper evaluates the effectiveness of the proposed system using free5GC. The evaluation demonstrated that performance variations among network slices influence video quality. These results indicate that dynamic network slice switching based on user stress levels has the potential to achieve QoE enhancement for users.

With the widespread Internet technologies, malware damage also spreads worldwide, making it necessary to address these issues urgently. In some cases, malware-infected terminals use the Domain Name System (DNS) when communicating with the Command and Control (C&C) servers to obtain information for attacks. The previous malware detection focuses on the DNS communication history of malware-infected terminals. However, this method has the problem of poor accuracy in detecting malicious domains when the analysis data is small. This paper proposes a malicious domain detection with the following improvements. The first improvement is adding information on response and time. The second improvement is shortening the query domain names to primary domain names. Further, the proposed method showed improvement in the experiment.

IEEE 802.11ah (11ah) is a wireless LAN standard using the 920 MHz band and is expected to be used in the IoT field as one of the Low Power Wide Areas (LPWAs). Many LPWAs share the 920 MHz band and are characterized by low transmission rates but long-range communication. Therefore, there is a high possibility of contending communication in the real-world environment. In this study, we clarify the characteristics of contending communications between 11ah and LoRa according to evaluating the performance using real devices.

Cyber Physical System (CPS) is a system that accumulates information from physical space, analyzes them in cyberspace, and then feeds back the results. We aim to realize a Floating Cyber Physical System (F-CPS), a regionally distributed CPS. We have proposed a large-capacity spatio-temporal data retention system for delivering data and function (application) in the F-CPS. In a previous work, we proposed a data completeness-aware transmission control and evaluated it by simulation. However, considering the movement of obstacles and fluctuation of radio waves in the real environment, packet loss occurs frequently. Thereby, the system may not be able to have complete data and may not function. In this paper, we proposed a method to recover missing data using redundant packets and evaluated its impact on the entire system by testing it with actual equipment.

LPWA (Low Power Wide Area) is expected to be a communication technology suitable for the Internet of Things (loT) because of its features. Since LoRa communication has a trade-off between communication range and transmission rate, performance is inherently varied depending on the surrounding environment. Therefore, to achieve stable and efficient communication performance, it is necessary to set appropriate parameters for LoRa depending on the communication environment between the base station and the terminal. We here propose a method for dynamic control of parameter settings based on reception statistics of beacons. The effectiveness of the proposed method is evaluated from the real experiments.

TCP congestion control uses end-to-end delay and packet discard information to control the transmission rate. In the wireless LAN, there is a time lag between TCP congestion control and the transmission rate control of the wireless LAN interfaces, and there is no coordination between the respective controls. Thus, congestion control corresponding to the current state of the wireless network can be achieved by shortening this time lag. Therefore, this paper proposes a method to control the congestion window by detecting changes in the transmission rate of the wireless LAN interfaces. Our proposed method enables to control congestion windows size by using data link layer information, instead of using only transport layer information. This paper verified the effectiveness of the proposed method by network simulator ns-3.40.

Low-power wide-area (LPWA) is a major communicaiton technology used in the Internet of Things (Io‘I’), Major sensor networks are constructed using original protocols specific to each LPWA standard and cannot communicate directly with devices connected to the Internet. To enhance the convenience of devices using LPWA, it is necessary to improve their interop-erability with Internet applications with TCP/IP. Previous study have enabled Single-hop TCP/IP communication over Private LoRa. In this study, we construct a multi-hop environment for TCP/IP communication over Private LoRa, and evaluate its performance using both UDP and TCP communication. Previous research has enabled one-to-one communication using UDP and TCP over a Private LoRa interface, an LPWA technology. This study leverages the characteristics of LPWA for ultra-Iong-distance transmission and implements TCP/IP communication in a multi-hop environment. This paper evaluates the performance of UDP and TCP on actual devices.

Spatio-temporal aware IoT applications need to deliver the Spatio-Temporal Data (STD), which depends on geographic location and time, to the users in real-time. We have proposed the STD retention system using crowds of vehicles to promote the immediate distribution and utilization of STDs in geographical proximity to the user. However, when the system retains a Large-size STD (LSTD) consisting of multiple packets such as videos and photos, the packet loss due to channel collisions should be suppressed for effective retention of an LSTD. In this paper, we propose a complementary data transmission control method with collision avoidance for LSTD retention and clarify the effectiveness of our proposed method by simulation.

QUIC is a secure, general-purpose transport protocol using congestion and retransmission controls on User Datagram Protocol (UDP). QUIC can use the same congestion control algorithms as Transmission Control Protocol (TCP). Thus, when communication between multiple terminals using QUIC competes, the performance of each terminal depends on the congestion control algorithm adopted by the terminal. In related works, the communication performance was evaluated by simulation when both CUBIC and BBR flows competed in TCP, and the results showed that each communication performance became unfair with the buffer size of the shared bottleneck link. In this study, we verify the communication performance at different bottleneck link buffer sizes when BBR and CUBIC compete through actual experiments.

IoT data includes Spatio-temporal data (STD) that is needed only at a specific time and place. In our previous research, we have proposed the STD data retention system (STD-RS), aiming to construct a novel architecture for STD distributing in a retention area by vehicles. However, since vehicles may distribute the STD in unexpected locations due to GPS errors or malicious behavior in a real environment. Therefore, we propose a reliability audit mechanism based on multi-layered blockchain managing and analyzing the history of STD distribution and vehicles' behavior in each retention area. Through simulation experiment, we demonstrated that our mechanism detects the malfunction of STD-RS effectively.

With the development and spread of IoT technology, the number of devices connected to the Internet is increasing. Some data generated by IoT devices include spatio-temporal data (STD) that depends on the location and time of data generation. Therefore, we have proposed the STD retention system (STD-RS) using vehicles as a network infrastructure for local production and consumption of STD. This paper proposes a transmission control method that can mitigate the fluctuation of RSS due to the influence of obstacles in the real environment and evaluates its effectiveness through experiments on actual devices.

Low-power wide-area (LPWA) is a major communication technology used in the Internet of Things (IoT). However, since LPWA does not conform to the TCP/IP protocol stack and employs its own unique protocol, sensors equipped with LPWA I/F face difficulty when connecting directly to the Internet. In a previous study, to extend general TCP/IP communication on LPWA networks, we constructed a TCP/IP network over Private LoRa, but it was found that TCP communication performance using LoRa devices was significantly degraded due to the characteristics of LPWA such as the low transmission rate. In the present study, to improve the performance of TCP communication using the Private LoRa interface, we propose a transmission control method that avoids collisions by modifying the advertised window size on IP2LoRa and demonstrate the effectiveness of the proposed method using TCP flow analysis.

Software-defined networking (SDN) has notably improved networks by providing Machine Learning-Powered programming capabilities at the control plane (CP), making it easier to dynamically manage the network resources according to varying traffic conditions. However, the geographically remote location of the CP from the data plane (DP) leads to significant round-trip delays in the order of milliseconds, which can ad-versely impact the performance of delay-sensitive and real-time traffic. To address this issue, this paper proposes a novel in-network reinforcement learning (RL) inference framework that extends programming capability from the CP to the DP for fine-grained control of network resources to meet the Quality of Service (QoS) demands of real-time applications. The in-network RL inference is achieved by adopting a match-action table mapping strategy in the DP and validating it through programming protocol-independent packet processors (P4). A P4 meter extern is utilized to allocate bandwidth to individual traffic flows based on their QoS requirements. Our proposed strategy achieves in-network RL inference at the line rate with negligible processing overhead while reducing packet loss rate and jitter by up to 92% and 57%, respectively, compared to the CP-based approach. Additionally, we evaluate the performance of our proposed bandwidth allocation framework using a state-of-the-art deep-deterministic policy gradient (DDPG)-based RL agent with a heuristic priority experience replay (hPER) technique. Our proposed DDPG agent achieves a faster convergence rate, higher reward, superior training stability, and up to 56 % reduction in operational cost compared to two alternative agents,

QUIC is a transport protocol that adds congestion control, retransmission control, and TLS to UDP. QUIC can use the same congestion control algorithms as TCP. In previous work, when both CUBIC and BBR flows compete within QUIC, we have shown that communication performance becomes unfair with respect to the buffer size of the shared bottleneck link. In this study, we improve the communication performance at different bottleneck link buffer sizes using Round Trip Time (RTT) and Explicit Congestion Notification (ECN) when CUBIC and BBR compete within QUIC through actual experiments.

Low-power wide-area (LPWA) is a major communication technology used in the Internet of Things (IoT). However, since LPWA does not conform to the TCP/IP protocol stack and employs its own unique protocol, it is difficult for sensors equipped with LPWA I/F to connect to the Internet directly. In the present study, to realize general TCP/IP communication on LPWA networks, we construct a TCP/IP network over Private LoRa, and evaluate its communication performance. Moreover, we verify the feasibility of TCP/IP communication over LoRa by using a popular Internet application.

Some specific services for Internet of Things, such as real-time map and providing local weather information, depend strongly on geographical time and location. We refer to the data for such service as spatio-temporal data (STD). When STD is used in a query response system similar to conventional Internet services, users not only need to acquire data actively as required, they must also have functions for retrieving data available STD. Therefore, we propose an STD retention system that uses vehicles as information hubs (InfoHubs) for disseminating and retaining the data in a specific area. In our system, InfoHubs diffuse, maintain, and advertise STD over places and times where the STD are strongly dependent, thereby allowing users to receive such data passively within the specific area. Additionally, because STD are associated with a particular space, the system can reduce search costs. We also propose an adaptive transmission control method that each vehicle effectively operates its wireless resources autonomously and STD are retained and distributed efficiently. Finally, we evaluated our proposed method using simulations and clarified that our proposed system is capable of achieving a coverage rate of nearly 100% for STD while reducing the number of data transmissions compared to existing systems.

Wireless LAN access points (APs) and stations (STAs) are widespread. In such an environment, APs with different specifications, such as IEEE 802.11a and 802.11ac, or different settings, such as very high throughput technology, are simultaneously operated in proximity. In this paper, we propose a new STA-centric AP selection method that maximizes the throughput performance while achieving “airtime fairness” on all channels. In our proposed method, each STA dynamically adjusts the frame size based on its own transmission rate for achieving airtime fairness. Furthermore, the STA calculates the predicted throughput of all of available APs, and then selects the AP with the highest predicted throughput for improving the throughput performance. Through simulations, we demonstrated that each STA reliably connects to an AP with better throughput performance, thereby increasing the total throughput performance in a heterogeneous Wi-Fi environment.

To facilitate local production and consumption (LPAC) of spatio-temporal data (STD) generated by Internet of Things (IoT) devices, we propose a STD retention system that works in collaboration with Mobile Edge Computing (MEC) infrastructure. In this paper, we will introduce the architecture of our proposed system and discuss its contributions and challenges.

Development of machine-to-machine communication technologies encourages an increasing amount of mobile traffic by smart phones, cellular phones, and various sensors. This traffic consists of small packets in order to minimize the influence of frame dropping in a data link layer. However, it is necessary to reduce the number of packets flowing into the core network to chunk packets, while satisfying the application requirement of users. In this paper, we propose the expiration timer control method for QoS-aware packet chunking. Our proposed scheme achieves a decrease in the number of packets flowing into the core network while satisfying the QoS of users by adjusting the waiting time for packet chunking depending on the condition of the core network. In this paper, we evaluate the proposed scheme by performing simulations and show that our proposed scheme achieves not only a decrease in packet flow into the core network but also the maintenance of QoS requirement for applications.

Multihop wireless networks (MWNs) can dynamically extend the coverage area of wireless local area networks (LANs). Communication performance of MWNs that use a single channel decreases due to interference between nodes occurring when frames are being relayed. In this paper, we proposed an autonomous dynamic transmission scheduling scheme for MWNs that is based on the behavior of neighbor nodes. In our proposed scheme, each node has a transmission priority obtained by monitoring neighboring nodes. Because it is difficult for low priority node to obtain the right to transmit a frame, the proposed scheme can mitigate interferences among nodes. In this paper, we evaluate the proposed scheme by performing simulations, and show that it can improve performance in MWN communications.

Mobile Ad-hoc Networks (MANETs) involve the establishment of wireless connections between mobile nodes, and can dynamically extend the coverage area of wireless local area networks (LAN). For MANETs that use a single channel, the communication performance decreases due to interferences between nodes when frames are being relayed. In this paper, we propose a priority control scheme based on neighbor node behavior for MANETs. A node continuously monitors neighbor nodes and determines a transmission priority on its own using monitoring results; the priority decreases when the node transmits a frame successfully, and increases when the node detects a transmitted frame from neighbor nodes. We evaluated the effectiveness of our proposed scheme using simulations, and results show that the throughput of our proposed scheme is at least approximately 700 kb/s higher than that of a MANET that uses IEEE 802.11a.

In IEEE 802.11a/b/g wireless LAN, STAs (stations) can select an appropriate transmission rate based upon the received signal strength in order to achieve high throughput. In such a multi-rate environment, however, the total throughput is degraded if an AP (access point) is shared by STAs at both high and low transmission rates simultaneously. This problem is identified as the performance anomaly problem in only IEEE 802.11b, and we closely examine it under the IEEE 802.11a multi-rate environment. Although earlier studies have assumed that this performance anomaly always occurs, we show that it does not occur under a certain environment. First, we describe the mechanism of the performance anomaly, then illustrate the condition under which the performance anomaly does not occur. Finally, we show, through simulation results, the condition under which a performance anomaly may and may not occur in a multirate environment.

Multi-hop wireless networks (MWNs) are rapidly gaining attention, because they can provide a wide coverage area to Internet users. To provide stable and high-performance network environments, security issues must be addressed. This paper focuses on the security issues in terms of anomalous relay nodes inside networks because their malicious behaviors can degrade the performance of MWNs. To maintain the network performance of MWNs, we propose a novel network reconfiguration scheme that each node reconstructs a network autonomously using the I/F of the neighbor nodes linked to a misbehaving node. Our proposed scheme reconfigurates topology with an emphasis on the reuse of I/F, the number of the links required to construct, transmission rates, performance anomaly, and network connectivity. We evaluate the effectiveness of the proposed schemes by simulations. The results of simulation indicate that the proposed scheme can prevent the communication performance degradation of the entire MWN.