Dongmin Choi

Power Allocation Scheme for Femto-to-Macro Downlink Interference Reduction for Smart Devices in Ambient Intelligence

In this paper, we present an analysis on the characteristics of cross-tier interference in regard to femtocells deployed in LTE cellular networks. We also present a cross-tier SLNR-based water filling (CSWF) power allocation algorithm for the reduction of interference from femtocell to macrocell for smart devices used in ambient intelligence. The results of this study show that CSWF significantly improves the macro UE performance around a femtocell access point (AP) from the SINR and throughput perspective. The CSWF algorithm also provides a relative gain on the throughput of femtocell UEs compared to frequency partitioning. Furthermore, the proposed algorithm has a low complexity and is implemented on the femto-AP side only, therefore not affecting the macro system.

Channel allocation and power control schemes for cross-tier 3GPP LTE networks to support multimedia applications

In this paper, we present the framework of a channel allocation (CA) and power control (PC) schemes for the minimization of interference in cross-tier 3GPP LTE networks that aim to support internet of multimedia things. Channel allocation scheme based on an interference graph preserving the minimum number of interfered MUEs by femtocells (IG-MIM) is proposed to mitigate interference amongst femtocells, and a game theory based power control algorithm is also proposed to reduce interference to surrounding macrocell users (MUEs). The proposed IG-MIM scheme constructs the interference graph based on a predefined threshold and allocates the subchannels to the femtocells that maintain the smallest number of interfered MUEs. For the power control, we design a payoff function based on the rewards from the achieved data rates and the penalties from the interference in regards to its adjacent femtocells. The simulation results show that the IG-MIM channel allocation significantly improves the SINR performance for the femtocell users (FUEs) being served; the game theory based power control decreases the power requirements of a femtocell and alleviates the interference to the MUEs.

Coordinated Scheduling Algorithm for System Utility Maximization With Heterogeneous QoS Requirements in Wireless Relay Networks

In this paper, we focus on the radio resource management (RRM) issues in the two-hop Orthogonal Frequency Division Multiple Access (OFDMA) system with heterogeneous quality of service (QoS) requirements. To solve the RRM problem, we first propose a new two-hop frame structure to support the data relay operation from the base station to the relay station and cooperative transmission for the edge users. Then, a two-hop coordinated scheduling algorithm is proposed, which utilizes the proposed two-hop frame structure and considers the corresponding interference status. The proposed two-hop coordinated scheduling algorithm solves the RRM problem of the two-hop OFDMA system with heterogeneous QoS requirements in an iterative manner, and so maximizes the system utility.

User biometric information-based secure method for smart devices

Secure mechanisms have been adapted to satisfy the needs of mobile subscribers; however, the mobile environment is quite different from a desktop PC or laptop‐based environment. The existing attack patterns in mobile environments are also quite different, and the countermeasures applied should be enhanced. In regards to usability, the mobile environment is based on mobility, and thus, mobile devices are designed and developed to enhance the owners efficiency. To avoid forgetting passwords, people are willing to adopt simple alphanumeric‐character combinations, which are easy to remember and convenient to enter. As a result, the passwords have a high probability of being cracked or exposed. In this paper, we study the potential security problems caused by simple and weak passwords, discuss drawbacks of some conventional works, and propose 3 creative schemes to increase the complexity and strength of passwords by applying the envisioned features. Note that our proposals are based on the assumption that the textual passwords are not difficult for users to remember or enter and do not cause inconvenience to users. In other words, the proposed methods can increase the complexity of simple passwords without the awareness of users.

Case study on password complexity enhancement for smart devices

Smart devices have already become a dally necessity of our life since they play a pivot role to record massive amount of Information of our personal life. Current Internet of TWngs era has been seeing more and more people relying on their devices. However, most people are losing patience to set complex passwords to ensure the security for their devices. To avoid forgetting the passwords, people are more willing to choose simple alphanumeric character combinations that are easy for them to remember and convenient to enter. Therefore, their passwords are of high probability to be cracked or exposed. In tWs paper, we study the potential security problems caused by simple and weak passwords, discuss the drawbacks of some conventional works, and propose three schemes to Increase the complexity of simple passwords. Note that our proposals are based on the prediction that the textual passwords are not difficult for users to remember or enter and the proposed schemes can effldently prevent passwords from being cracked or exposed.

Channel Model for Polarized MIMO Systems With Power Radiation Pattern Concern

Antenna polarization is an effective resource to be exploited for space-limited devices to support a large network payload. However, channel modeling with regard to antenna polarization is still in its early stages. This paper assesses several existing channel models that support antenna polarization, and the advantages and disadvantages of the existing models are clearly summarized. To maintain the advantages (e.g., supporting the MIMO array extension and considering the antenna radiation pattern) and overcome the disadvantages (e.g., reducing modeling complexity but preserving accuracy), this paper proposes a 3-D channel model for polarized MIMO (CM3D-PMIMO) systems. In particular, the proposed channel model considers the power radiation pattern of polarized array systems that could be used for evaluation of an energy efficient transmission technique based on polarized MIMO systems. Similar to conventional works, the proposed CM3D-PMIMO is verified via correlations between the polarized links, and the Monte Carlo simulation reliability for performance evaluation of MIMO technologies under CM3D-PMIMO is also validated by packet-error-rate analysis.

Epidemic spreading on a complex network with partial immunization

This paper proposes a new virus spreading model, susceptible–infected–susceptible–recovered–susceptible, which is based on partial immunization and immune invalidity in a complex network. On the basis of mean-field theory, the epidemic dynamics behavior of this model in a uniform network and a scale-free network is studied. After modifying the formula for the effective spread rate, we obtain the theoretical result that the coexistence of partial immunization and immune failure does not affect the network spread threshold. At the same time, the experimental results show that the existence of the above two conditions greatly increases the spread of the virus and extends the diffusion range. The study also found that in the scale-free network, peak viral infection occurs at the beginning of the spreading process, and after the immunization strategy is applied, the early infection peak is effectively curbed.

Signal reception for successive interference cancellation in NOMA downlink

Successive interference cancellation (SIC) receiver is adopted by power domain non-orthogonal multiple access (NOMA) at the receiver side as the baseline receiver scheme taking the forthcoming expected mobile device evolution into account. Development technologies and advanced techniques are boldly being considered in order to achieve power saving in many networks, to reach sustainability and reliability in communication due to envisioned huge amount of data delivery. In this paper, we propose a novel scheme of NOMA-SIC for the sake of balancing the trade-off between system performance and complexity. In the proposed scheme, each SIC level is comprised by a matching filter (MF), a MF detector and a regenerator. In simulations, the proposed scheme demonstrates the best performance on power saving, of which energy efficiency increases with an increase in the number of NOMA device pairs.

A survey on ocean observatory networks

Ocean observation networks have become important data acquisition platform for marine scientific research. This paper first summarizes the characteristics of the ocean observation networks, briefly introduces the development history of the world in the field of ocean observatory networks, and then gives a detailed introduction to the research progress of the ocean observatory networks in various countries. The paper also points out the key technologies and initial solutions of the ocean observatory network system, and discusses the next step development of the seabed observatory networks.

Study to Improve Security for IoT Smart Device Controller: Drawbacks and Countermeasures

Including mobile environment, conventional security mechanisms have been adapted to satisfy the needs of users. However, the device environment-IoT-based number of connected devices is quite different to the previous traditional desktop PC- or mobile-based environment. Based on the IoT, different kinds of smart and mobile devices are fully connected automatically via device controller, such as smartphone. Therefore, controller must be secure compared to conventional security mechanism. According to the existing security threats, these are quite different from the previous ones. Thus, the countermeasures applied should be changed. However, the smart device-based authentication techniques that have been proposed to date are not adequate in terms of usability and security. From the viewpoint of usability, the environment is based on mobility, and thus devices are designed and developed to enhance their owners’ efficiency. Thus, in all applications, there is a need to consider usability, even when the application is a security mechanism. Typically, mobility is emphasized over security. However, considering that the major characteristic of a device controller is deeply related to its owner’s private information, a security technique that is robust to all kinds of attacks is mandatory. In this paper, we focus on security. First, in terms of security achievement, we investigate and categorize conventional attacks and emerging issues and then analyze conventional and existing countermeasures, respectively. Finally, as countermeasure concepts, we propose several representative methods.