In Feb 2021, As the competition for commercialization of 5G mobile communication has been increasing, 5G SA Network and Vo5G are expected to be commercialized soon. 5G mobile communication aims to provide 20 Gbps transmission speed which is 20 times faster than 4G mobile communication, connection of at least 1 million devices per 1 km2, and 1 ms transmission delay which is 10 times shorter than 4G. To meet this, various technological developments were required, and various technologies such as Massive MIMO (Multiple-Input and Multiple-Output), mmWave, and small cell network were developed and applied in the area of 5G access network. However, in the core network area, the components constituting the LTE (Long Term Evolution) core network are utilized as they are in the NSA (Non-Standalone) architecture, and only the changes in the SA (Standalone) architecture have occurred. Also, in the network area for providing the voice service, the IMS (IP Multimedia Subsystem) infrastructure is still used in the SA architecture. Here, the issue is that while 5G mobile communication is evolving openly to provide various services, security elements are vulnerable to various cyber-attacks because they maintain the same form as before. Therefore, in this paper, we will look at what the network standard for 5G voice service provision consists of, and what are the vulnerable problems in terms of security. And We Suggest Possible Attack Scenario using Security Issue, We also want to consider whether these problems can actually occur and what is the countermeasure.

To ensure secure mobile communication, the communicating entities must know their mutual identities. The entities which need to be identified in a mobile communication system are mobile devices and the network. Third Generation Partnership Project (3GPP) has specified Evolved Packet System Authentication and Key Agreement (EPS AKA) procedure for the mutual authentication of user and the Long Term Evolution (LTE) network. EPS AKA certainly overcomes most of the vulnerabilities in the Global System for Mobile Communications (GSM) and Universal Mobile Telecommunication System (UMTS) access procedures. However, the LTE access procedure still has security weaknesses against some of the sophisticated security threats, such as, Denial-of-Service (DoS) attacks, Man-in-the-Middle (MitM) attacks, rogue base station attacks and fails to ensure privacy protection for some of the important parameters. This paper proposes an improved security framework for the LTE access procedure by ensuring the confidentiality protection of International Mobile Subscriber Identity (IMSI) and random-challenge RAND. Also, our proposed system is designed to reduce the impact of DoS attacks which try to overwhelm the network with useless computations. We use a one-time shared key with a short lifetime between the UE and MME to protect IMSI and RAND privacy. Finally, we explore the parameters design for the proposed system which leads to satisfy the requirements imposed on computational load and latency as well as security strength.

3GPP Long Term Evolution (LTE) is one of the most advanced technologies in the wireless and mobility field because it provides high speed data and sophisticated applications. LTE was originally deployed by service providers on various platforms using separate dedicated hardware in Access radio layer and the Evolved Packet Core network layer (EPC), thereby limiting the system's flexibility and capacity provisioning. Thus, the concept of virtualization was introduced in the EPC hardware to solve the dedicated hardware platform limitations. It was also introduced in the IP Multimedia Subsystem (IMS) and Machine to Machine applications (M2M) for the same reason. This paper provides a simulation model of a virtualized EPC and virtualized M2M transport application server connected via an external IP network, which has significant importance in the future of mobile networks. This model studies the virtualized server connectivity problem, where two separate virtual machines communicate via the existing external legacy IP network. The simulation results show moderate performance, indicating that the selection of IP technology is much more critical than before. The paper also models MPLS technology as a replacement for the external IP routing mechanism to provide traffic engineering and achieve more efficient network performance. Furthermore, to provide a real network environment, Poisson Pareto Burst Process (PPBP) traffic source is carried over the UDP transport layer which matches the statistical properties of real-life M2M traffic. Furthermore, the paper proves End-to-End interoperability of LTE and MPLS running GTP and MPLS Label Forwarding information Base (LFIB) and MPLS traffic engineering respectively. Finally, it looks at the simulation of several scenarios using Network Simulator 3 (NS-3) to evaluate the performance improvement over the traditional LTE IP architecture under M2M traffic load.

In this paper, we design a stealthy GSM phone identity catcher. As the GSM protocols do not mandate the authentication of BSes (Base Stations) to MSes (Mobile Stations), fake BSes can be implemented to lure victims to register with and thereby intercept crucial information of the user, including their identities. However, the straightforward implementation of GSM phone identity catcher can be easily perceived by users employing detection software due to such phenomena as phone interface changes and service interruptions. In this paper, we propose several effective mechanisms, such as smart configuration of the fake BSes, quick attachment/detachment and service relay, to make the catching process invisible to users and software. Real world experiments have been conducted and the results prove the efficiency and stealth of our proposed GSM phone identity catcher. We hope our work could help to enhance the effectiveness of IMSI catching attack and thereby alert the industry to design stronger authentication protocol in communication systems.

We considered the oxygen diffusivity around a conductive filament of resistive switching oxides, with the aim of designing material appropriate for highly reliable non-volatile memory. Both theoretical and experimental analyses were performed for this consideration. The theoretically obtained oxygen chemical potential difference, which works as a driving force for diffusion, significantly depends on a material. Then, we experimentally confirmed that the oxygen diffusion behaviors vary greatly depending on the chemical potential differences.

It is known that the IP Multimedia Subsystem (IMS) provides various telecom services e.g., VoIP, instant messaging, and video conferencing. In the IMS, these services are provided with session initiation protocol (SIP) handled by call/session control function servers (CSCFs). Completing the SIP signaling call flow without delay is vital to provide satisfactory services to the users. For service continuity, previous studies redundantly synchronized session states of CSCFs with backup servers. This paper proposes an IMS restoration system that selectively stores the session states. This is achieved by utilizing the retransmission mechanism of SIP. Time-based simulation emulating the process of backup servers shows that the proposed system reduces the number of backup servers to less than 38% compared to the previous studies, without degrading the service quality.

The widespread adoption of IP-based telecommunication core networks is leading to a paradigm shift in international interconnection where the traditional Time-Division Multiplexing (TDM) interconnection between telecommunication networks is being replaced by IP interconnection. IP eXchange (IPX) is an emerging paradigm in international IP interconnection that has novel requirements, such as an end-to-end Quality of Service (QoS) guarantee across multiple carriers. IPX is a future direction for international telecommunications, but it is not easy to understand the overall concept of IPX because it is derived from a wide variety of services, technical knowledge, and telecommunication backgrounds. The confusion and complexity of the technical elements hinder the development of IPX. Thus, this paper clarifies the state-of-the-art technical elements from an IPX perspective and discusses ongoing challenges and emerging services on IPX, particularly end-to-end QoS, Voice over IP issues, IP Multimedia Subsystem (IMS) interworking, and Long Term Evolution (LTE) roaming. This paper also surveys published academic research studies that were not focused primarily on IPX but which are likely to provide potential solutions to the challenges.

We propose a new cognitive radio network architecture using the IP multimedia subsystem (IMS) functionality. We implement the cognitive radio network entities standardized in IEEE 1900.4 on the IMS that exchanges RAN and terminal context information between the networks and the terminals to make optimum and immediate reconfiguration decisions. In our proposed architecture, RAN context information is obtained from cellular networks which are directly connected to the IMS. The presence management functions of the IMS are applied to exchange those information in a “push” manner, which enables immediate notification of changes in wireless environment. We evaluate the performance of the proposed context information exchange method, by comparing with the cases that adequate and immediate RAN context information is not available. The evaluation results show that the proposed framework gives 10–30% superior performance than the conventional cognitive radio networks.

The IP Multimedia Subsystem (IMS) establishes a session between end terminals as a client/server application in the Next Generation Network (NGN). These days, many application services are being provided as Web services. In this letter, we propose a new NGN architecture conforming to the architectural styles of Representational State Transfer (REST), which is a Web service technology for solving interoperability and traffic concentration problems in the Session Initiation Protocol (SIP).

To improve the high voltage performance of AlGaN/GaN heterojunction field effect transistors (HFETs), we have fabricated AlGaN/GaN HFETs with p-GaN epi-layer on sapphire substrate with an ohmic contact to the p-GaN (p-sub HFET). Substrate bias dependent threshold voltage variation (VT-VSUB) was used to directly determine the doping concentration profile in the buffer layer. This VT-VSUB method was developed from Si MOSFET. For HFETs, the insulator is formed by epitaxially grown and heterogeneous semiconductor layer while for Si MOSFETs the insulator is amorphous SiO2. Except that HFETs have higher channel mobility due to the epitaxial insulator/semiconductor interface, HFETs and Si MOSFETs are basically the same in the respect of device physics. Based on these considerations, the feasibility of this VT-VSUB method for AlGaN/GaN HFETs was discussed. In the end, the buffer layer doping concentration was measured to be 21017 cm-3, p-type, which is well consistent with the Mg concentration obtained from secondary ion mass spectroscopy (SIMS) measurement.

Selecting transparently a proper network connection for voice communication will be a fundamental requirement in future multi-mode heterogeneous wireless network. This paper presented a smart session selection (S3) scheme to meet this requirement. Instead of selecting a best access network as in conventional Always Best Connected (ABC) paradigm, S3 enables users to select a best network connection, which consists of source and destination access network pair, to satisfy quality constraint and users' preference. To support S3, we develop a user profile to specify network connection priority. Meanwhile IP multimedia subsystem (IMS) is extended to make smart decision for users. Finally, Analytic Hierarchy Process (AHP) is used to recommend a network connection with assistance of user profile and IMS signaling. An example is illustrated to show that AHP can successfully select a good network connection that fulfills the requirement of users.

Based on the mutuality between arrival moments of uplink and downlink messages, this paper proposes a scheme that assigns different time-out thresholds for mobile terminal sleep mode operation according to the direction of the message just processed. Simulation results prove that, this approach can increase the power saving factor of a mobile terminal without degrading QoS.

In July 2006, International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) Study Group 13 initiated the approval process for a batch of framework Recommendations on the Next Generation Network (NGN) Release 1. One of the new Recommendations, Y.2012, illustrates the NGN from the viewpoint of a functional architecture consisting of various functional blocks, namely functional entities. In conjunction with this Recommendation, this paper explains how the NGN can be built and how the NGN utilizes functional entities to provide expected services and required capabilities. This paper also identifies open issues for extending the functional architecture towards Release 2.

Cryptosystems for smartcard are required to provide protection from Differential Power Analysis (DPA) attack. Self-timed circuit based cryptosystems demonstrate considerable resistance against DPA attack, but they take substantial circuit area. A novel approach offering up to 30% area reduction and maintaining DPA protection level close to DIMS scheme is proposed.

We prepared HfO2 films by atomic layer deposition (ALD) on three kinds of silicon substrate surfaces (chemical oxide, HF-last surface and thermal oxide), and characterized their morphologies, structures, compositions, and crystallinities by physical analysis. The results revealed that the as-deposited HfO2 films consisted of nano-crystalline particles with a different crystalline system from that of the annealed films. The size of the nano-crystalline particles on the film on the chemical oxide was smaller than those on the other surfaces. The reason is thought to be the difference in OH concentration on the substrate surface. The predominant crystalline phases of all HfO2 films were monoclinic after annealing. Moreover, the film prepared on the chemical oxide had the smoothest surface after annealing. However, island structures with grain boundaries developed in the films on the other surfaces.

This paper evaluates the performance of TCP over ATM by simulation studies to clarify its applicability to high-speed WANs. We compared the performance of TCP over ABR with that of TCP over UBR, and TCP over UBR with Early Packet Discard (EPD). As for TCP over UBR, TCP has all responsibilities for end-to-end performance. In this case, cell loss at the ATM layer degrades TCP performance. Optimum tuning of TCP parameters may mitigate this degradation problem, but cannot solve it. Using EPD with UBR can fairly reduce useless transmission of corrupted packets and improve TCP performance, but still have the problem on fairness. As a result, TCP over ABR was proved to be the most effective as long as it suppressed cell loss. It was also proved that, if we want to extract best performance by TCP over ABR, we need to choose TCP parameters such as window size or timer granularity, so that ABR rate control does not interact with TCP window control and retransmission control.

We investigate performance of TCP protocol over ATM networks by using a simulation technique. As the ATM layer, we consider (1) rate-based control of the ABR service class and (2) an EPD (Early Packet Discard) technique applied to the UBR service class and (3) and EPD with per-VC accounting for fairness enhancement applied to the UBR service class. In comparison, we adopt a multi-hop network model where the multiple ATM switches are interconnected. In such a network, unfairness among connections is a possible cause of the problem due to differences of the number of hops and/or the round trip times among connections. Simulation results show that the rate-based control method of ABR achieves highest throughput and best fairness in most circumstances. However, the performance of TCP over ABR is degraded once the cell loss takes place due to the inappropriate control parameter setting. To avoid this performance degradation, we investigate the appropriate parameter set suitable to TCP on ABR service. As a result, parameter tuning can improve the performance of TCP over ABR, but limited. We therefore consider TCP over ABR with EPD enhancement where the EPD technique is incorporated into ABR. We last consider the multimedia network environment, where the VBR traffic exists in the network in addition to the ABR/UBR traffic. By this, we investigate an applicability of the above observations to a more generic model. Through simulation experiments, we find that the similar results can be obtained, but it is also shown that parameters of the rate-based congestion control must be chosen carefully by taking into account the existence of VBR traffic. For this, we discuss the method to determine the appropriate control parameters.

Isotope dilution secondary ion mass spectroscopy (ID-SIMS) using 30Si as a spike is investigated as a quantitative analysis method for trace amounts of Si. For a standard solution of Si, the relateve standard deviation of results using this method is 5% for 0.2 µg Si, and the determination lower limit is 18 ng. Using this method, the amount of Si deposited on the Ge(100) surface by the self-limited adsorption of SiH2Cl2 is determined to be about 1.00.2 monolayer.