Energy-Optimal Collaborative GPS Localization with Short Range Communication

Abstract-The key issue of the localization study is that how we can minimize the energy consumption of devices with guaranteeing high degree of accuracy. In this paper, we show that the collaboration among proxy devices with short range communication is helpful to energy-efficiently localize their locations in time-average sense by analyzing the device proximity including real GPS trace of students in KAIST and NCSU campuses. Next, we deliberate what is the best method for selfish mobile users to collaborate for the energy-efficient localization, and formulate an optimization problem which considers the energy efficiency and/or user fairness. However, optimizing this problem is tricky since it requires a global knowledge of sets of proxy devices and also solving a NP-hard problem to select devices which directly measure locations. This paper makes a contribution towards presenting a practical and fully distributed location sharing protocol based on competition for turning off GPS, and an optimal algorithm which controls mean waiting time used for the competition. Through the extensive simulations under several sample topologies and real mobility trace in KAIST campus, we obtain the following interesting observations: (i) (in sample topologies) our scheme achieves a near-optimal performance of proposed problem in terms of energy efficiency and fairness (up to 27.2% power saving with 35.8% higher fairness than existing heuristic algorithms), (ii) (in real mobility trace) our scheme well adapts at even unpredictably changing mobility environment (65.5% power saving than no collaboration, 27.4% or more power saving with 25% higher fairness than the existing algorithms)

Induced neural stem cells from distinct genetic backgrounds exhibit different reprogramming status

Somatic cells could be directly converted into induced neural stem cells (iNSCs) by ectopic expression of defined transcription factors. However, the underlying mechanism of direct lineage transition into iNSCs is largely unknown. In this study, we examined the effect of genetic background on the direct conversion process into an iNSC state. The iNSCs from two different mouse strains exhibited the distinct efficiency of lineage conversion as well as clonal expansion. Furthermore, the expression levels of endogenous NSC markers, silencing of transgenes, and in vitro differentiation potential were also different between iNSC lines from different strains. Therefore, our data suggest that the genetic background of starting cells influences the conversion efficiency as well as reprogramming status of directly converted iNSCs.ope

Survey on 6G System for AI-Native Services

As the Fifth-generation (5G) environment becomes widespread, various services tailored to these environmental standards are being provided. In line with this, computer vision based artificial intelligence (AI)-Native services such as AR/VR (augmented reality/virtual reality) and realistic services have emerged, but it is difficult to satisfy the requirements of these services. In a 5G environment, mobile edge computing (MEC) and cloud computing infrastructure are independent, making it difficult to provide AI-Native services in a sixth-generation (6G) environment, and the interface of the wireless network is also limited to the general services that can be provided in a 5G environment. In this paper, we specify the service-side limitations of the 5G environment through the survey of AI-Native services. Additionally, it presents a direction to move forward in the 6G system for an environment in which AI-Native services are delivered seamlessly. © 2022 IEEE

Advanced Multibeam Satellite Network Security with Encryption and Beamforming Technologies

For B5G/6G networks, security will be a critical issue due to data explosion from the launch of non-terrestrial net-works (NTN) and space-terrestrial integrated networks (STIN). To this end, encryption and physical layer security (PLS) on top of the NTN or STIN have been studied extensively. However, a use of either encryption or PLS only has critical drawbacks: the encryption induces an additional power or time cost, while the performance of PLS can be limited by the capability of eavesdroppers (Eves). In this paper, we propose a multibeam satellite network security solution by exploiting encryption and beamforming technologies. Satellites are assumed to be capable of transmitting two types of encrypted and non-encrypted signals for broadcast and private messages, simultaneously. We first design a security threat under non-colluding and colluding eavesdropping attacks. Thereafter, we explore power allocation, user selection, and beam scheduling based on security threats and channel conditions over satellite downlinks in orthogonal multiple access (OMA) and non-orthogonal multiple access (NOMA) systems, respectively. We show the improved secrecy performance of the proposed method compared to the secrecy capacity of PLS. Finally, the simulation results demonstrate that NOMA has better total capacity and secrecy performances than OMA. © 2022 IEEE

Cross-Layer Encryption of CFB-AES-TURBO for Advanced Satellite Data Transmission Security

As the advanced satellite network can provide extremely diverse data to various types of users, it is of vital importance to achieve data security using encryption over satellite channels. However, since the avalanche effect makes encryption techniques vulnerable to bit errors in the wireless channel, a more powerful encryption technique is required for data confidentiality. In addition, an efficient method for exchanging encryption keys between receivers and transmitters should be capable of managing a large scale of satellites in the network. In this paper, we propose a novel super-encryption method of joint encryption and channel coding, CFB-AES-TURBO, which combines advanced encryption standard (AES) in the upper layer and turbo coding as bulk encryption in the physical layer. Because we introduce turbo coding in the cipher feedback (CFB) mode with AES for each block, our scheme can accomplish dual goals of data protection and bit error correction. We select a encryption block size to maximize throughput based on channel conditions and the security level required for a user, and present a key exchanging solution. We derive processing time gains and analyze computational complexity of the CFB-AES-TURBO. The bit error rate (BER) performance improvement with about 12 dB coding gain is achieved. We also enhance the security performance by 1015,000 times and provide indistinguishability. Finally, we analyze the total expected latency, suggest the minimum key refresh time of geostationary earth orbit (GEO) satellites. © IEEE1

Satellite Network Slice Planning: Architecture, Performance Analysis, and Open Issues

For beyond-5G and 6G communications, the satellite-terrestrial integrated network (STIN) is expected to provide diverse services with global coverage. The first step in implementing a successful STIN is to make the satellite network capable of functioning seamlessly with its terrestrial counterpart. However, as satellites rotate around Earth at very high speeds and are connected over very long wireless links, it is almost impossible to use terrestrial schemes without modification.TRU

Analysis of Low-Latency Virtual Network Resource Reservation for LEO Satellite Network

For beyond 5G and 6G communications, the satellite terrestrial integrated network (STIN) is expected to provide diverse services with seamless coverage. The first step for implementing the STIN is to make the satellite network capable of supporting advanced functions that the terrestrial counterpart is providing. In this paper, network virtualization with network slices, which is actively studied in the terrestrial network, is analyzed for the satellite network. The main difference between satellite and terrestrial networks is the mobility of satellites. Since the slice services require end-to-end connectivity, the satellite network topology change due to the mobility of satellites can give a huge impact to the slices. The latency is analyzed with time-varying satellite topology with an assumption that the virtual network resource for slice is reserved for low latency. For simulations, the minimum number of handovers is assumed and the end-to-end latency is analyzed for its initial latency, average latency, minimum latency, and maximum latency during the service time of slices in the satellite network. © 2022 IEEE

Joint Transmission and Computation Power Allocations for Satellite Communication Security

Due to introduction of the non-terrestrial network (NTN) and satellite-air-terrestrial integrated network (SATIN), many applications using satellites are being expected and this will result in a severe security issue. In this paper, we propose a satellite communication security method that jointly considers signal transmission and security computation power based on the orthogonal multiple access (OMA). Before transmission, satellite estimates a security threat based on the number of eavesdroppers (Eves) in the large satellite beam coverage as wide as 50 km for LEO satellites at the L-band. With the security threat, the satellite splits onboard power for signals and security, and controls a beam size. Through the sum capacity optimization problem, we derive the optimal onboard power allocation and security algorithm selection with respect to security threats and channel conditions. © 2022 IEEE