检索结果-南通市图书馆

Joint optimization of user association and resource allocation in cache-enabled terrestrial-satellite integrating network

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2021年第8期64卷 90-103页

作者： Shuang NI Junyu LIU Min SHENG Jiandong LI Xiaona ZHAO State Key Laboratory of Integrated Service Networks Xidian University

Although low earth orbit(LEO) satellites can provide high-capacity backhaul to serve the terrestrial network, the performance of terrestrial-satellite communication systems is critically influenced by the coupling of user association and resource allocation in this integrating system, where user association includes small-cell base station(SBS)-user association and SBS-satellite association. In this work, we consider a cache-enabled terrestrial-satellite integrating network, in which LEO satellites provide backhaul for cacheenabled SBSs to serve ground users. Targeting at maximizing the downlink sum rate of the system and the number of accessed ground users, we formulate an optimization problem where user association and resource allocation of both terrestrial and satellite networks are joint optimized. Owing to the coupling relationship and integer programming nature of this optimization problem, we use Lagrangian relaxation to decouple and decompose it into two subproblems. We propose a user-division matching(UDM) algorithm by dividing all users into multiple user groups, which skillfully solves the first subproblem with multi-objectives. Afterward,to depict the nature of multi-connectivity sufficiently, the second subproblem is converted into a many-toone matching game and solved by a modified Gale-Shapely(MGS) algorithm, which is highly efficient for different satellite constellations. Simulation results demonstrate the proposed algorithms can significantly improve the downlink sum rate of the system by 28.5–120.7 compared to the benchmark algorithms in the typical settings and balance the tradeoff between the downlink sum rate of the system and the number of accessed ground users. Moreover, it also shows that <1% system performance loss can be obtained by the proposed method compared to the optimal solution.

关键词： terrestrial-satellite integrating network content caching user association resource allocation satellite backhaul

A True-Time-Delay Array Architecture for Wideband Multi-Beam Tracking

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

China Communications 2023年第8期20卷 65-77页

作者： Xiaowei Liu Guangliang Ren State Key Laboratory of Integrated Service Networks Xidian UniversityXi’an 710071China

The true-time delay(TTD)units are critical for solving beam squint and frequency selective fading inWideband Large-Scale Antenna Systems(LSASs).In this work,we propose a TTD array architecture for wideband multi-beam tracking that eliminates the beam squint phenomenon and filters out interference signals by applying a spatial filter and time delay estimations(TDEs).The paper presents a novel approach to spatial filter design by introducing a transformation matrix that can optimize the beam response in a specific direction and at a specific frequency.Using the variable fractional delay(VFD)filters,we propose a TDE algorithm with a Newton-Raphson iteration update process that corrects the arrival time delay difference between sensors.Simulations and examples have demonstrated that the proposed architecture can achieve beam tracking within 10 ms at the low signalto-noise ratio(SNR)and demodulation loss is less than 0.5 dB in wideband multi-beam scenarios.

关键词： true-time delay(TTD) spatial filter variable fractional delay(VFD) wideband multi-beam tracking time delay estimation(TDE)

Resource Trading and Miner Competition in Wireless Blockchain networks with Edge Computing

在线全文

学校读者我要写书评

暂无评论

China Communications 2023年第11期20卷 187-201页

作者： Yuchen Zhou Jian Chen Lu Lyu Bingtao He The State Key Laboratory of Integrated Service Networks Xidian UniversityXi’an 710071China

To promote the application of edge com-puting in wireless blockchain networks,this paper presents a business ecosystem,where edge comput-ing is introduced to assist blockchain users in imple-menting the mining process.This paper exploits re-source trading and miner competition to enable se-cure and efficient transactions in the presented busi-ness ecosystem.The resource trading problem is for-mulated as a Stackelberg game between miner candi-dates and edge computing servers,where computing,caching,and communication resources are jointly op-timized to maximize the potential profit.Partial of-floading is introduced to further enhance the system performance when compared with the existing work.We analyze the existence and uniqueness of the Nash equilibrium and Stackelberg equilibrium.Based on the optimization result,winners are selected from the set of miner candidates by bidding and constitute the mining network.Simulation results demonstrate that the proposal is able to improve the social welfare of blockchain miners,thus stimulating more blockchain users to join the mining network.

关键词： blockchain edge computing miner com-petition resource trading social welfare

Coverage enhancement for 6G satellite-terrestrial integrated networks: performance metrics, constellation configuration and resource allocation

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2023年第3期66卷 40-59页

作者： Min SHENG Di ZHOU Weigang BAI Junyu LIU Haoran LI Yan SHI Jiandong LI State Key Laboratory of Integrated Service Networks Xidian University Department of Broadband Communication Peng Cheng Laboratory

Since the base station-centric wireless coverage mode of 5G is difficult to support future stereoscopic global wireless coverage demands, the future infrastructure of 6G satellite-terrestrial integrated network(STIN) with mega constellations will extend from the terrestrial network to the integrated satellite-terrestrial architecture, so as to realize the improvement of wireless coverage capability through extending the spatial and temporal coverage. However, what are the specific quantitative indicators of wireless coverage? What is the basis for the effect of network configuration with mega constellations on coverage performance? How to form non-uniform coverage through intelligent resource scheduling to match non-uniformly distributed service requirements in the future 6G STIN? The aforementioned unknown fundamental problems have become a bottleneck restricting the further development of coverage expansion in the future 6G STIN. In this paper,we start with the evolution route of wireless coverage and the vision of 6G coverage and propose coverage performance evaluation metrics in 6G STINs from the perspective of signal coverage, capacity coverage, and service coverage. Furthermore, we investigate the relationship between coverage structure and coverage capability in 6G STINs with mega constellations and we find network structure characteristics suitable for 6G non-uniform service requirements, thus guiding constellation design in 6G STINs by analyzing and comparing the coverage performance of several typical mega constellations. Afterwards, we explore the application of artificial intelligence in resource collaboration to provide technology reference to enhance coverage capability for dynamic 6G service demands. Finally, we analyze possible technical challenges for improving service coverage performance in 6G STINs to provide researchers with new ideas.

关键词： 6G satellite-terrestrial integrated networks on-demand wireless coverage performance metrics constellation configuration intelligent resource scheduling

The GAC Property of a Class of 1-Resilient Functions with High Nonlinearity

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2020年第2期29卷 220-227页

作者： GE Hui SUN Yujuan XIE Chunlei State Key Laboratory of Integrated Service Networks Xidian University state key laboratory of Cryptology

The absolute and sum-of-squares indicators are used to evaluate the Global avalanche characteristics(GAC) of Boolean functions in a global manner. The GAC properties of a class of highly nonlinear 1-resilient Boolean functions are given. We derive new upper bounds of the absolute and sumof-squares indicators for a class of 1-resilient Boolean functions with high nonlinearity. Compared to the known1-resilient Boolean functions, the constructed functions possess higher nonlinearity and better GAC properties.

关键词： Boolean functions Global avalanche characteristics Resiliency Nonlinearity Stream ciphers

An integrated Image Task Planning in Satellite networks:From Instruction Release and Observation Perspective

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

China Communications 2023年第5期20卷 288-301页

作者： Di Zhou Yixin Wang Min Sheng Chengyuan Tang Jiandong Li State Key Laboratory of Integrated Service Networks Xidian UniversityXi’anShaanxi 710071China

The unreasonable observation arrangements in the satellite operation control center(SOCC)may result in the observation data cannot be downloaded as scheduled.Meanwhile,if the operation instructions released by the satellite telemetry tracking center(STTC)for the on-board payloads are not injected on the specific satellites in time,the corresponding satellites cannot perform the observation operations as planned.Therefore,there is an urgent need to design an integrated instruction release,and observation task planning(I-IRO-TP)scheme by efficiently collaborating the SOCC and STTC.Motivated by this fact,we design an interaction mechanism between the SOCC and the STTC,where we first formulate the I-IRO-TP problem as a constraint satisfaction problem aiming at maximizing the number of completed tasks.Furthermore,we propose an interactive imaging task planning algorithm based on the analysis of resource distribution in the STTC during the previous planning periods to preferentially select the observation arcs that not only satisfy the requirements in the observation resource allocation phase but also facilitate the arrangement of measurement and control instruction release.We conduct extensive simulations to demonstrate the effectiveness of the proposed algorithm in terms of the number of completed tasks.

关键词： satellite networks integrated instruction release and observation task planning resource allocation resource distribution prediction

Enabling Efficient Caching in High Mobility UAV Communications Network under Limited Backhaul

在线全文

学校读者我要写书评

暂无评论

China Communications 2022年第10期19卷 207-219页

作者： Yan Wu Jiandong Li Junyu Liu Min Sheng Chenxi Zhao State Key Laboratory of Integrated Service Networks Xidian UniversityXi'anShaanxi 710071China

Due to flexible deployment,unmanned aerial vehicle(UAV)mounted aerial access points are capable of expanding the coverage capabilities of existing terrestrial base stations(TBSs).Different from TBSs,however,UAV access points(UAPs)are of high mobility in horizontal and vertical dimensions,which may deteriorate the coverage performance.Worsestill,the mobility of UAPs would as well increase the pressure of wireless backhaul.In this light,we investigate the performance of the cache-enabled UAV communications network(CUCN)in terms of network spatial throughput(ST)by analyzing the line of sight(LoS)connections and non-line of sight(NLoS)connections.It is found that the network ST is exponentially decreased with the square of UAP altitude.Furthermore,contrary to intuition,a large cache size may deteriorate the network ST when UAPs are over-deployed.The reason is that a large cache size increases the hit probability,which may increase the activation of UAPs and consequently result in complicated interference.Aiming to maximize the network ST,we optimize the cache strategy under limited backhaul.Remarkably,the results show that network ST could be substantially improved by the optimized cache strategy and the performance degeneration brought by UAP high mobility could be even eliminated especially when the UAP altitude is high.

关键词： caching optimization UAV communications network spatial throughput stochastic geometry aerial access point

6G service Coverage with Mega Satellite Constellations

在线全文

学校读者我要写书评

暂无评论

China Communications 2022年第1期19卷 64-76页

作者： Min Sheng Di Zhou Weigang Bai Junyu Liu Jiandong Li State Key Laboratory of Integrated Service Networks Xidian UniversityXi’anShaanxi710071China

The rapid development and continuous updating of the mega satellite constellation(MSC)have brought new visions for the future 6G coverage extension, where the global seamless signal coverage can realize ubiquitous services for user terminals. However, global traffic demands present nonuniform characteristics. Therefore, how to ensure the on-demand service coverage for the specific traffic demand, i.e., the ratio of traffic density to service requirement per unit area, is the core issue of 6G wireless coverage extension exploiting the MSC. To this regard, this paper first discusses the open challenges to reveal the future direction of 6G wireless coverage extension from the perspective of key factors affecting service coverage performance, i.e., the network access capacity, space segment capacity and their matchingrelationship. Furthermore, we elaborate on the key factors affecting effective matchings of the aforementioned aspects, thereby improving service coverage capability.

关键词： 6G mega satellite constellations on-demand service coverage un-uniform traffic demands resource management

Experimental and numerical demonstration of hierarchical time-delay reservoir computing based on cascaded VCSELs with feedback and multiple injections

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2024年第2期67卷 279-290页

作者： Xingxing GUO Shuiying XIANG Xingyu CAO Biling GU State Key Laboratory of Integrated Service Networks Xidian University state key Discipline laboratory of Wide Bandgap Semiconductor Technology School of MicroelectronicsXidian University

In this paper, we propose and demonstrate experimentally and numerically a hierarchical timedelay optical reservoir computing(RC) system based on cascaded vertical-cavity surface-emitting lasers(VCSELs) with feedback and multiple injections. The prediction performance characteristics of the hierarchical time-delay RC system based on cascaded VCSELs under different reservoir layers are compared.Evidently, the prediction performance of the hierarchical time-delay RC system is first improved and saturates as the number of reservoir layers increases. Besides, the impacts of key factors on predicting the hierarchical time-delay RC system are also analyzed in detail experimentally and numerically. This proposed hierarchical time-delay RC system based on VCSELs is useful for the further development of RC systems and may be beneficial to improve the ability of RC systems to solve more complex problems.

关键词： vertical-cavity surface-emitting laser reservoir computing neuromorphic photonics time-delay system information processing