The emerging deployment of large-scale Low Earth Orbit(LEO)satellite constellations provides seamless global coverage.However,the increasing number of satellites also introduces significant security challenges,such as...The emerging deployment of large-scale Low Earth Orbit(LEO)satellite constellations provides seamless global coverage.However,the increasing number of satellites also introduces significant security challenges,such as eavesdropping and illegal communication behavior detection.This paper investigates covert wireless communication over uplink satellite-terrestrial network,focusing on scenarios with warden satellites.By accounting for shot noise generated by ambient signals from terrestrial interferers,the terrestrial transmitter Alice can effectively hide its signal from warden satellites.Leveraging stochastic geometry,the distributions of distances between transmitter and satellites are analyzed,enabling the assessment of uplink performance and interference within a satellite’s coverage area.Approximate expressions for detection error probability and transmission outage probability are derived.Based on the theoretical analysis,an optimal scheme is proposed to maximize covert throughput under the constraint of the average detection error probability of the most detrimental warden satellite.Extensive Monte Carlo simulations experiments are conducted to validate the accuracy of analytical methods for evaluating covert performance.展开更多
In this paper,we analyze the capacity and delay performance of a large-scale Unmanned Aerial Vehicle(UAV)-enabled wireless network,in which untethered and tethered UAVs deployed with content files move along with mobi...In this paper,we analyze the capacity and delay performance of a large-scale Unmanned Aerial Vehicle(UAV)-enabled wireless network,in which untethered and tethered UAVs deployed with content files move along with mobile Ground Users(GUs)to satisfy their coverage and content delivery requests.We consider the case where the untethered UAVs are of limited storage,while the tethered UAVs serve as the cloud when the GUs cannot obtain the required files from the untethered UAVs.We adopt the Ornstein-Uhlenbeck(OU)process to capture the mobility pattern of the UAVs moving along the GUs and derive the compact expressions of the coverage probability and capacity of our considered network.Using tools from martingale theory,we model the traffic at UAVs as a two-tier queueing system.Based on this modeling,we further derive the analytical expressions of the network backlog and delay bounds.Through numerical results,we verify the correctness of our analysis and demonstrate how the capacity and delay performance can be significantly improved by optimizing the percentage of the untethered UAVs with cached contents.展开更多
In the blockchain,the consensus mechanism plays a key role in maintaining the security and legitimation of contents recorded in the blocks.Various blockchain consensus mechanisms have been proposed.However,there is no...In the blockchain,the consensus mechanism plays a key role in maintaining the security and legitimation of contents recorded in the blocks.Various blockchain consensus mechanisms have been proposed.However,there is no technical analysis and comparison as a guideline to determine which type of consensus mechanism should be adopted in a specific scenario/application.To this end,this work investigates three mainstream consensus mechanisms in the blockchain,namely,Proof of Work(PoW),Proof of Stake(PoS),and Direct Acyclic Graph(DAG),and identifies their performances in terms of the average time to generate a new block,the confirmation delay,the Transaction Per Second(TPS)and the confirmation failure probability.The results show that the consensus process is affected by both network resource(computation power/coin age,buffer size)and network load conditions.In addition,it shows that PoW and PoS are more sensitive to the change of network resource while DAG is more sensitive to network load conditions.展开更多
The Industrial Internet is a promising technology combining industrial systems with Internet connectivity to significantly improve the product efficiency and reduce production cost by cooperating with intelligent devi...The Industrial Internet is a promising technology combining industrial systems with Internet connectivity to significantly improve the product efficiency and reduce production cost by cooperating with intelligent devices,in which the advanced computing,big data analysis and intelligent perception techniques have been involved.This paper comprehensively surveys the recent advances of the Industrial Internet,including reference architectures,key technologies,relative applications and future challenges.Reference architectures which have been proposed for different application scenarios and their corresponding characteristics are summarized.Key technologies,such as cloud computing,mobile edge computing,fog computing,which are classified according to different layers in the architecture,are presented to support a variety of applications in the Industrial Internet.Meanwhile,future challenges and research trends are discussed as well to promote further research of the Industrial Internet.展开更多
with the rapid development of mobile intemet and Internet of Things applications, the conventional centralized cloud computing is encountering severe challenges, such as high latency, low Spectral Efficiency （SE）, a...with the rapid development of mobile intemet and Internet of Things applications, the conventional centralized cloud computing is encountering severe challenges, such as high latency, low Spectral Efficiency （SE）, and nonadaptive machine type of communication. Motivated to solve these challenges, a new technology is driving a trend that shifts the function of centralized cloud computing to edge devices of networks. Several edge computing technologies originating from different backgrounds to decrease latency, improve SE, and support the massive machine type of communication have been emerging. This paper comprehensively presents a tutorial on three typical edge computing technologies, namely mobile edge computing, cloudlets, and fog computing. In particular, the standardization efforts, principles, architectures, and applications of these three technologies are summarized and compared. From the viewpoint of radio access network, the differences between mobile edge computing and fog computing are highlighted, and the characteristics of fog computing-based radio access network are discussed. Finally, open issues and future research directions are identified as well.展开更多
Reconfigurable intelligent surface(RIS)can manipulate the wireless propagation environment by smartly adjusting the amplitude/phase in a programmable panel,enjoying the improved performance.The accurate acquisition of...Reconfigurable intelligent surface(RIS)can manipulate the wireless propagation environment by smartly adjusting the amplitude/phase in a programmable panel,enjoying the improved performance.The accurate acquisition of the instantaneous channel state information(CSI)in the cascaded RIS chain makes an indispensable contribution to the performance gains.However,it is quite challenging to estimate the CSI in a time-variant scenario due to the limited signal processing capability of the passive elements embedded in a RIS pannel.In this work,a channel estimation scheme for the RIS-assisted wireless communication system is proposed,which is demonstrated to perform well in a time-variant scenario.The cascaded RIS channel is modeled as a state-space model based upon the mobility situations.In addition,to fully exploit the time correlation of channel,Kalman filter is employed by taking the prior information of channels into account.Further,the optimal reflection coefficients are derived according to the minimum mean square error(MMSE)criterion.Numerical results show that the proposed methods exhibit superior performance if compared with a conventional channel estimation scheme.展开更多
In 5G systems, massive multiple-input multiple-output (MIMO) has been adopted in base stations (BSs) to improve spectral efficiency and coverage. The traditional conductive performance test techniques are challenging ...In 5G systems, massive multiple-input multiple-output (MIMO) has been adopted in base stations (BSs) to improve spectral efficiency and coverage. The traditional conductive performance test techniques are challenging due to the unaffordable cost and high complexity when testing a large number of antennas. To solve this problem, the over-the-air (OTA) test has been presented, in which probe selection is the key to reduce the number of channel emulators and probes. In this paper, a novel artificial bee colony (ABC) algorithm is introduced to enhance the efficiency and accuracy of probe selection procedure. A sectoring- based multi-probe anechoic chamber (MPAC) is built to evaluate the throughput performance of massive MIMO equipped in 5G BS. In addition, link level simulation is carried out to evaluate the proposal’s performance gain under the commercial network assumptions, where the average throughput of three velocity is given with different SNR region. The results suggest that OTA chamber and multi-probe wall are available not only for 5G BSs, but also for user equipments (UEs) with end-to-end communication.展开更多
Molecular communication(MC) is a kind of communication technology based on biochemical molecules for internet of bio-nano things, in which the biochemical molecule is used as the information carrier for the interconne...Molecular communication(MC) is a kind of communication technology based on biochemical molecules for internet of bio-nano things, in which the biochemical molecule is used as the information carrier for the interconnection of nano-devices. In this paper, the basic principle of diffusion based MC and the corresponding key technologies are comprehensively surveyed. In particular, the state-ofthe-art achievements relative to the diffusion based MC are discussed and compared, including the system model, the system performance analysis with key influencing factors, the information coding and modulation techniques. Meanwhile, the multi-hop nano-network based on the diffusion MC is presented as well. Additionally, given the extensiveness of the research area, open issues and challenges are presented to spur future investigations, in which the involvement of channel model, information theory, self-organizing nano-network, and biochemical applications are put forward.展开更多
In order to alleviate capacity constraints on the fronthaul and decrease the transmit latency, a hierarchical content caching paradigm is applied in the fog radio access networks(F-RANs). In particular, a specific clu...In order to alleviate capacity constraints on the fronthaul and decrease the transmit latency, a hierarchical content caching paradigm is applied in the fog radio access networks(F-RANs). In particular, a specific cluster of remote radio heads is formed through a common centralized cloud at the baseband unit pool, while the local content is directly delivered at fog access points with edge cache and distributed radio signal processing capability. Focusing on a downlink F-RAN, the explicit expressions of ergodic rate for the hierarchical paradigm is derived. Meanwhile, both the waiting delay and latency ratio for users requiring a single content are exploited. According to the evaluation results of ergodic rate on waiting delay, the transmit latency can be effectively reduced through improving the capacity of both fronthaul and radio access links. Moreover, to fully explore the potential of hierarchical content caching, the transmit latency for users requiring multiple content objects is optimized as well in three content transmission cases with different radio access links. The simulation results verify the accuracy of the analysis, further show the latency decreases significantly due to the hierarchical paradigm.展开更多
To accommodate the diversified emerging use cases in 5G,radio access networks(RAN)is required to be more flexible,open,and versatile.It is evolving towards cloudification,intelligence and openness.By embedding computi...To accommodate the diversified emerging use cases in 5G,radio access networks(RAN)is required to be more flexible,open,and versatile.It is evolving towards cloudification,intelligence and openness.By embedding computing capabilities within RAN,it helps to transform RAN into a natural cost effective radio edge computing platform,offering great opportunity to further enhance RAN agility for diversified services and improve users’quality of experience(Qo E).In this article,a logical architecture enabling deep convergence of communication and computing in RAN is proposed based on O-RAN.The scenarios and potential benefits of sharing RAN computing resources are first analyzed.Then,the requirements,design principles and logical architecture are introduced.Involved key technologies are also discussed,including heterogeneous computing infrastructure,unified computing and communication task modeling,joint communication and computing orchestration and RAN computing data routing.Followed by that,a VR use case is studied to illustrate the superiority of the joint communication and computing optimization.Finally,challenges and future trends are highlighted to provide some insights on the potential future work for researchers in this field.展开更多
The forking problem plays a key role in the security issue,which is a major concern in the blockchain system.Although many works studied the attack strategy,consensus mechanism,privacy-protecting and security performa...The forking problem plays a key role in the security issue,which is a major concern in the blockchain system.Although many works studied the attack strategy,consensus mechanism,privacy-protecting and security performance analysis,most of them only address the intentional forking caused by a malicious attacker.In fact,without any attacker,unintentional forking still remains due to transmission delay and failure,especially in wireless network scenarios.To this end,this paper investigates the reason for generating unintentional forking and derives the forking probability expression in Wireless Blockchain Networks(WBN).Furthermore,in order to illustrate the unintentional forking on the blockchain system,the performances in terms of resource utilization rate,block generation time,and Transaction Per Second(TPS)are investigated.The numerical results show that the target difficulty of hash algorithm in generating a new block,the delay time of broadcasting,the network scale,and the transmission failure probability would affect the unintentional forking probability significantly,which can provide a reliable basis for avoiding forking to save resource consumption and improving system performance.展开更多
Satellite-Terrestrial integrated Networks(STNs)have been advocated by both academia and industry as a promising network paradigm to achieve service continuity and ubiquity.However,STNs suffer from problems including p...Satellite-Terrestrial integrated Networks(STNs)have been advocated by both academia and industry as a promising network paradigm to achieve service continuity and ubiquity.However,STNs suffer from problems including poor flexibility of network architecture,low adaptability to dynamic environments,the lack of network intelligence,and low resource utilization.To handle these challenges,a Software defined Intelligent STN(SISTN)architecture is introduced.Specifically,the hierarchical architecture of the proposal is described and a distributed deployment scheme for SISTNs controllers is proposed to realize agile and effective network management and control.Moreover,three use cases in SISTNs are discussed.Meanwhile,key techniques and their corresponding solutions are presented,followed by the identification of several open issues in SISTNs including compatibility with existing networks,the tradeoff between network flexibility and performance,and so on.展开更多
With the rapid increasing of maritime activities, maritime wireless networks(MWNs) with high reliability, high energy efficiency, and low delay are required. However, the centralized networking with fixed resource sch...With the rapid increasing of maritime activities, maritime wireless networks(MWNs) with high reliability, high energy efficiency, and low delay are required. However, the centralized networking with fixed resource scheduling is not suitable for MWNs due to the special environment. In this paper,we introduce the collaborative relay communication in distributed MWNs to improve the link reliability, and propose an orthogonal time-frequency resource block reservation based multiple access(RRMA) scheme for both one-hop direct link and two-hop collaborative relay link to reduce the interference. To further improve the network performance, we formulate an energy efficiency(EE) maximization resource allocation problem and solve it by an iterative algorithm based on the Dinkelbach method. Finally, numerical results are provided to investigate the proposed RRMA scheme and resource allocation algorithm, showing that the low outage probability and transmission delay can be attained by the proposed RRMA scheme. Moreover,the proposed resource allocation algorithm is capable of achieving high EE in distributed MWNs.展开更多
Satellite communication has been seen as a vital part of the sixth generation communication,which greatly extends network coverage.In satellite communication,resource management is a key problem attracting many resear...Satellite communication has been seen as a vital part of the sixth generation communication,which greatly extends network coverage.In satellite communication,resource management is a key problem attracting many research interests.However,previous study mainly focuses on throughput improvement via power allocation and spectrum assignment and the proposed approaches are mostly model-based and dedicated to specific problem structures.Fortunately,with the trend of edge intelligence,complex resource management problems can be efficiently resolved in a model-free manner.In this paper,a joint beam activation,user-beam association and time resource allocation approach is proposed.The core idea is using stochastic learning at the ground station to identify active user-link beams to meet user rate demand.In addition,the convergence,optimality and complexity of our proposal are rigorously discussed.By simulation,it is shown that the rate goal of most of the users can be met and meanwhile satellite energy is saved owing to much less active beams.展开更多
As the permeation of artificial intelligence(AI)in wireless applications,some data-driven and computing-intensive services are emerging,such as mobile high-definition AR/VR,and real-time fingertip interactions.Moreove...As the permeation of artificial intelligence(AI)in wireless applications,some data-driven and computing-intensive services are emerging,such as mobile high-definition AR/VR,and real-time fingertip interactions.Moreover,the application scenarios have been extended to penetrate the vertical industry,which have multi-dimension and diverse quality of service(QoS)requirements.Recently,the research and the development of 6G have been triggered,and much higher QoS requirements of data rate,latency,and connectivity will be raised.展开更多
Intent-Based Networks(IBNs),which are originally proposed to introduce Artificial Intelligence(AI)into the sixth-generation(6G)wireless networks,can effectively solve the challenges of traditional networks in terms of...Intent-Based Networks(IBNs),which are originally proposed to introduce Artificial Intelligence(AI)into the sixth-generation(6G)wireless networks,can effectively solve the challenges of traditional networks in terms of efficiency,flexibility,and security.IBNs are mainly used to transform users’business intent into network configuration,operation,and maintenance strategies,which are prominent for designing the AI-enabled 6G networks.In particular,in order to meet the massive,intelligent service demands and overcome the time-varying radio propagation,IBNs can continuously learn and adapt to the time-varying network environment based on the massive collected network data in real-time.From the aspects of both the core network and radio access network,this article comprehensively surveys the architectures and key techniques of IBNs for 6G.In particular,the demonstration platforms of IBNs,such as the Apstra Operating System,Forward Networks Verification Platform,and One Convergence Service Interaction Platform,are presented.Moreover,the industrial development of IBNs is elaborated,including the emerging new products and startups to solve the problems of open data platforms,automated network operations,and preemptive network fault diagnosis.Finally,several open issues and challenges are identified as well to spur future researches.展开更多
With Wireless communications in the 0.1-10TeraHertz(THz)band are envisioned as one of the key enablers towards ubiquitous wireless communications beyond 5G accommodating a massive number of connected devices and ultra...With Wireless communications in the 0.1-10TeraHertz(THz)band are envisioned as one of the key enablers towards ubiquitous wireless communications beyond 5G accommodating a massive number of connected devices and ultra-high user data rates in the order of Tera-bit-per-second.The THz band is located between the millimeter-wave(mmWave)and the far infrared(IR)band and still considered as one of the least investigated and exploited regions in the electromagnetic spectrum.展开更多
The edge cache is an effective way to reduce the heavy traffic load and the end-to-end latency in radio access networks(RANs)for supporting a number of critical Internet of Things(IoT)services and applications.It has ...The edge cache is an effective way to reduce the heavy traffic load and the end-to-end latency in radio access networks(RANs)for supporting a number of critical Internet of Things(IoT)services and applications.It has been verified to provide high spectral efficiency,high energy efficiency,and low latency.To exploit the advantages of edge cache,a paradigm of fog computing-based radio access networks(F-RANs)has emerged to provide great flexibility to satisfy quality-of-service requirements of various IoT applications in the fifth generation(5G)wireless systems.展开更多
Driven by diverse intelligent applications,computing capability is moving from the central cloud to the edge of the network in the form of small cloud nodes,forming a distributed computing power network.Tasked with bo...Driven by diverse intelligent applications,computing capability is moving from the central cloud to the edge of the network in the form of small cloud nodes,forming a distributed computing power network.Tasked with both packet transmission and data processing,it requires joint optimization of communications and computing.Considering the diverse requirements of applications,we develop a dynamic control policy of routing to determine both paths and computing nodes in a distributed computing power network.Different from traditional routing protocols,additional metrics related to computing are taken into consideration in the proposed policy.Based on the multi-attribute decision theory and the fuzzy logic theory,we propose two routing selection algorithms,the Fuzzy Logic-Based Routing(FLBR)algorithm and the low-complexity Pairwise Multi-Attribute Decision-Making(l PMADM)algorithm.Simulation results show that the proposed policy could achieve better performance in average processing delay,user satisfaction,and load balancing compared with existing works.展开更多
Although content caching and recommendation are two complementary approaches to improve the user experience,it is still challenging to provide an integrated paradigm to fully explore their potential,due to the high co...Although content caching and recommendation are two complementary approaches to improve the user experience,it is still challenging to provide an integrated paradigm to fully explore their potential,due to the high complexity and complicated tradeoff relationship.To provide an efficient management framework,the joint design of content delivery and recommendation in wireless content caching networks is studied in this paper.First,a joint transmission scheme of content objects and recommendation lists is designed with edge caching,and an optimization problem is formulated to balance the utility and cost of content caching and recommendation,which is an mixed integer nonlinear programming problem.Second,a reinforcement learning based algorithm is proposed to implement real time management of content caching,recommendation and delivery,which can approach the optimal solution without iterations during each decision epoch.Finally,the simulation results are provided to evaluate the performance of our proposed scheme,which show that it can achieve lower cost than the existing content caching and recommendation schemes.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant No.U22B2006.
文摘The emerging deployment of large-scale Low Earth Orbit(LEO)satellite constellations provides seamless global coverage.However,the increasing number of satellites also introduces significant security challenges,such as eavesdropping and illegal communication behavior detection.This paper investigates covert wireless communication over uplink satellite-terrestrial network,focusing on scenarios with warden satellites.By accounting for shot noise generated by ambient signals from terrestrial interferers,the terrestrial transmitter Alice can effectively hide its signal from warden satellites.Leveraging stochastic geometry,the distributions of distances between transmitter and satellites are analyzed,enabling the assessment of uplink performance and interference within a satellite’s coverage area.Approximate expressions for detection error probability and transmission outage probability are derived.Based on the theoretical analysis,an optimal scheme is proposed to maximize covert throughput under the constraint of the average detection error probability of the most detrimental warden satellite.Extensive Monte Carlo simulations experiments are conducted to validate the accuracy of analytical methods for evaluating covert performance.
基金supported in part by the National Key Research and Development Program of China under Grant 2021YFB2900200National Natural Science Foundation of China under No.62001047,61925101,61831002,and 61921003+2 种基金the Beijing Natural Science Foundation under Grant L223007the Beijing Municipal Science and Technology Project NO.Z211100004421017the Young Elite Scientist Sponsorship Program by China Institute of Communications.
文摘In this paper,we analyze the capacity and delay performance of a large-scale Unmanned Aerial Vehicle(UAV)-enabled wireless network,in which untethered and tethered UAVs deployed with content files move along with mobile Ground Users(GUs)to satisfy their coverage and content delivery requests.We consider the case where the untethered UAVs are of limited storage,while the tethered UAVs serve as the cloud when the GUs cannot obtain the required files from the untethered UAVs.We adopt the Ornstein-Uhlenbeck(OU)process to capture the mobility pattern of the UAVs moving along the GUs and derive the compact expressions of the coverage probability and capacity of our considered network.Using tools from martingale theory,we model the traffic at UAVs as a two-tier queueing system.Based on this modeling,we further derive the analytical expressions of the network backlog and delay bounds.Through numerical results,we verify the correctness of our analysis and demonstrate how the capacity and delay performance can be significantly improved by optimizing the percentage of the untethered UAVs with cached contents.
基金the National Natural Science Foundation of China under Grant 61701059,Grant 61941114,and Grant 61831002,in part by the Fundamental Research Funds for the Central Universities of New TeachersProject,in part by the Chongqing Technological Innovation and Application Development Projects under Grant cstc2019jscx-msxm1322,and in part by the Eighteentg Open Foundation of State Key Lab of Integrated Services Networks of Xidian University under Grant ISN20-05.
文摘In the blockchain,the consensus mechanism plays a key role in maintaining the security and legitimation of contents recorded in the blocks.Various blockchain consensus mechanisms have been proposed.However,there is no technical analysis and comparison as a guideline to determine which type of consensus mechanism should be adopted in a specific scenario/application.To this end,this work investigates three mainstream consensus mechanisms in the blockchain,namely,Proof of Work(PoW),Proof of Stake(PoS),and Direct Acyclic Graph(DAG),and identifies their performances in terms of the average time to generate a new block,the confirmation delay,the Transaction Per Second(TPS)and the confirmation failure probability.The results show that the consensus process is affected by both network resource(computation power/coin age,buffer size)and network load conditions.In addition,it shows that PoW and PoS are more sensitive to the change of network resource while DAG is more sensitive to network load conditions.
基金the State Major Science and Technology Special Projects(Grant 2018ZX03001023-005)the National Natural Science Foundation of China under Grant No.61831002,61728101,and 61671074the Beijing Natural Science Foundation under Grant No.JQ18016.
文摘The Industrial Internet is a promising technology combining industrial systems with Internet connectivity to significantly improve the product efficiency and reduce production cost by cooperating with intelligent devices,in which the advanced computing,big data analysis and intelligent perception techniques have been involved.This paper comprehensively surveys the recent advances of the Industrial Internet,including reference architectures,key technologies,relative applications and future challenges.Reference architectures which have been proposed for different application scenarios and their corresponding characteristics are summarized.Key technologies,such as cloud computing,mobile edge computing,fog computing,which are classified according to different layers in the architecture,are presented to support a variety of applications in the Industrial Internet.Meanwhile,future challenges and research trends are discussed as well to promote further research of the Industrial Internet.
基金This work was supported in part by the National Natural Science Foundation of China under Grant No. 61361166005, the National High Technology Research and Development Program of China under Grant No. 2014AA01A701, the National Basic Research Program of China （973 Program） under Grant No. 2013CB336600, and the State Major Science and Technology Special Projects （Grant No. 2016ZX03001020-006）.
文摘with the rapid development of mobile intemet and Internet of Things applications, the conventional centralized cloud computing is encountering severe challenges, such as high latency, low Spectral Efficiency （SE）, and nonadaptive machine type of communication. Motivated to solve these challenges, a new technology is driving a trend that shifts the function of centralized cloud computing to edge devices of networks. Several edge computing technologies originating from different backgrounds to decrease latency, improve SE, and support the massive machine type of communication have been emerging. This paper comprehensively presents a tutorial on three typical edge computing technologies, namely mobile edge computing, cloudlets, and fog computing. In particular, the standardization efforts, principles, architectures, and applications of these three technologies are summarized and compared. From the viewpoint of radio access network, the differences between mobile edge computing and fog computing are highlighted, and the characteristics of fog computing-based radio access network are discussed. Finally, open issues and future research directions are identified as well.
基金supported in part by National Natural Science Foundation of China(Grant Nos.61921003,61925101,61831002 and 61901315)in part by the Beijing Natural Science Foundation under(Grant No.JQ18016)in part by the Fundamental Research Funds for the Central Universities(Grant No.2020RC08).
文摘Reconfigurable intelligent surface(RIS)can manipulate the wireless propagation environment by smartly adjusting the amplitude/phase in a programmable panel,enjoying the improved performance.The accurate acquisition of the instantaneous channel state information(CSI)in the cascaded RIS chain makes an indispensable contribution to the performance gains.However,it is quite challenging to estimate the CSI in a time-variant scenario due to the limited signal processing capability of the passive elements embedded in a RIS pannel.In this work,a channel estimation scheme for the RIS-assisted wireless communication system is proposed,which is demonstrated to perform well in a time-variant scenario.The cascaded RIS channel is modeled as a state-space model based upon the mobility situations.In addition,to fully exploit the time correlation of channel,Kalman filter is employed by taking the prior information of channels into account.Further,the optimal reflection coefficients are derived according to the minimum mean square error(MMSE)criterion.Numerical results show that the proposed methods exhibit superior performance if compared with a conventional channel estimation scheme.
基金supported by the State Major Science and Technology Special Projects under Grant No. 2018ZX03001028-003
文摘In 5G systems, massive multiple-input multiple-output (MIMO) has been adopted in base stations (BSs) to improve spectral efficiency and coverage. The traditional conductive performance test techniques are challenging due to the unaffordable cost and high complexity when testing a large number of antennas. To solve this problem, the over-the-air (OTA) test has been presented, in which probe selection is the key to reduce the number of channel emulators and probes. In this paper, a novel artificial bee colony (ABC) algorithm is introduced to enhance the efficiency and accuracy of probe selection procedure. A sectoring- based multi-probe anechoic chamber (MPAC) is built to evaluate the throughput performance of massive MIMO equipped in 5G BS. In addition, link level simulation is carried out to evaluate the proposal’s performance gain under the commercial network assumptions, where the average throughput of three velocity is given with different SNR region. The results suggest that OTA chamber and multi-probe wall are available not only for 5G BSs, but also for user equipments (UEs) with end-to-end communication.
基金supported in part by the National Natural Science Foundation of China (Grant No.61361166005)the State Major Science and Technology Special Projects (Grant No.2016ZX03001020006)
文摘Molecular communication(MC) is a kind of communication technology based on biochemical molecules for internet of bio-nano things, in which the biochemical molecule is used as the information carrier for the interconnection of nano-devices. In this paper, the basic principle of diffusion based MC and the corresponding key technologies are comprehensively surveyed. In particular, the state-ofthe-art achievements relative to the diffusion based MC are discussed and compared, including the system model, the system performance analysis with key influencing factors, the information coding and modulation techniques. Meanwhile, the multi-hop nano-network based on the diffusion MC is presented as well. Additionally, given the extensiveness of the research area, open issues and challenges are presented to spur future investigations, in which the involvement of channel model, information theory, self-organizing nano-network, and biochemical applications are put forward.
基金supported in part by the National Natural Science Foundation of China (Grant No.61361166005)the State Major Science and Technology Special Projects (Grant No.2016ZX03001020006)the National Program for Support of Top-notch Young Professionals
文摘In order to alleviate capacity constraints on the fronthaul and decrease the transmit latency, a hierarchical content caching paradigm is applied in the fog radio access networks(F-RANs). In particular, a specific cluster of remote radio heads is formed through a common centralized cloud at the baseband unit pool, while the local content is directly delivered at fog access points with edge cache and distributed radio signal processing capability. Focusing on a downlink F-RAN, the explicit expressions of ergodic rate for the hierarchical paradigm is derived. Meanwhile, both the waiting delay and latency ratio for users requiring a single content are exploited. According to the evaluation results of ergodic rate on waiting delay, the transmit latency can be effectively reduced through improving the capacity of both fronthaul and radio access links. Moreover, to fully explore the potential of hierarchical content caching, the transmit latency for users requiring multiple content objects is optimized as well in three content transmission cases with different radio access links. The simulation results verify the accuracy of the analysis, further show the latency decreases significantly due to the hierarchical paradigm.
基金jointly supported by the Beijing University of Posts and Telecommunications-China Mobile Research Institute Joint Innovation Centerthe National Key Research and Development Program of China under Grant 2021YFB2900200the National Natural Science Foundation of China under Grant 62201073 and 61925101。
文摘To accommodate the diversified emerging use cases in 5G,radio access networks(RAN)is required to be more flexible,open,and versatile.It is evolving towards cloudification,intelligence and openness.By embedding computing capabilities within RAN,it helps to transform RAN into a natural cost effective radio edge computing platform,offering great opportunity to further enhance RAN agility for diversified services and improve users’quality of experience(Qo E).In this article,a logical architecture enabling deep convergence of communication and computing in RAN is proposed based on O-RAN.The scenarios and potential benefits of sharing RAN computing resources are first analyzed.Then,the requirements,design principles and logical architecture are introduced.Involved key technologies are also discussed,including heterogeneous computing infrastructure,unified computing and communication task modeling,joint communication and computing orchestration and RAN computing data routing.Followed by that,a VR use case is studied to illustrate the superiority of the joint communication and computing optimization.Finally,challenges and future trends are highlighted to provide some insights on the potential future work for researchers in this field.
基金This work was supported in part by the National Natural Science Foundation of China under Grant 61701059,Grant 61941114,and Grant 61831002in part by the Fundamental Research Funds for the Central Universities of New Teachers Project,in part by the Basic and Advanced Research Projects of CSTC(No.cstc2019jcyj-zdxmX0008)+2 种基金in part by the Chongqing Science and Technology Innovation Leading Talent Support Program(CSTCCXLJR-C201710,and CSTCCXLJRC201908)in part by Chongqing Technological Innovation and Application Development Projects(cstc2019jscx-msxm1322)in part by the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZD-K201900605).
文摘The forking problem plays a key role in the security issue,which is a major concern in the blockchain system.Although many works studied the attack strategy,consensus mechanism,privacy-protecting and security performance analysis,most of them only address the intentional forking caused by a malicious attacker.In fact,without any attacker,unintentional forking still remains due to transmission delay and failure,especially in wireless network scenarios.To this end,this paper investigates the reason for generating unintentional forking and derives the forking probability expression in Wireless Blockchain Networks(WBN).Furthermore,in order to illustrate the unintentional forking on the blockchain system,the performances in terms of resource utilization rate,block generation time,and Transaction Per Second(TPS)are investigated.The numerical results show that the target difficulty of hash algorithm in generating a new block,the delay time of broadcasting,the network scale,and the transmission failure probability would affect the unintentional forking probability significantly,which can provide a reliable basis for avoiding forking to save resource consumption and improving system performance.
基金This work was supported in part by the National Key Research and Development Program of China under Grant 2020YFB1806703in part by the National Natural Science Foundation of China under Grant 62001053,Grant 61831002,and Grant 61925101in part by Young Elite Scientist Sponsorship Program by China Institute of Communications,and in part by the BUPT Excellent Ph.D.Students Foundation under Grant CX2020106.
文摘Satellite-Terrestrial integrated Networks(STNs)have been advocated by both academia and industry as a promising network paradigm to achieve service continuity and ubiquity.However,STNs suffer from problems including poor flexibility of network architecture,low adaptability to dynamic environments,the lack of network intelligence,and low resource utilization.To handle these challenges,a Software defined Intelligent STN(SISTN)architecture is introduced.Specifically,the hierarchical architecture of the proposal is described and a distributed deployment scheme for SISTNs controllers is proposed to realize agile and effective network management and control.Moreover,three use cases in SISTNs are discussed.Meanwhile,key techniques and their corresponding solutions are presented,followed by the identification of several open issues in SISTNs including compatibility with existing networks,the tradeoff between network flexibility and performance,and so on.
基金supported in part by the National Natural Science Foundation of China under Grant 62001056, 61925101, U21A20444in part by the Fundamental Research Funds for the Central Universities under Grant 500421336 and Grant 505021163。
文摘With the rapid increasing of maritime activities, maritime wireless networks(MWNs) with high reliability, high energy efficiency, and low delay are required. However, the centralized networking with fixed resource scheduling is not suitable for MWNs due to the special environment. In this paper,we introduce the collaborative relay communication in distributed MWNs to improve the link reliability, and propose an orthogonal time-frequency resource block reservation based multiple access(RRMA) scheme for both one-hop direct link and two-hop collaborative relay link to reduce the interference. To further improve the network performance, we formulate an energy efficiency(EE) maximization resource allocation problem and solve it by an iterative algorithm based on the Dinkelbach method. Finally, numerical results are provided to investigate the proposed RRMA scheme and resource allocation algorithm, showing that the low outage probability and transmission delay can be attained by the proposed RRMA scheme. Moreover,the proposed resource allocation algorithm is capable of achieving high EE in distributed MWNs.
基金supported in part by the National Natural Science Foundation of China(No.62001053)the Beijing Municipal Science and Technology Project(No.Z211100004421017)Young Elite Scientist Sponsorship Program by China Institute of Communications.
文摘Satellite communication has been seen as a vital part of the sixth generation communication,which greatly extends network coverage.In satellite communication,resource management is a key problem attracting many research interests.However,previous study mainly focuses on throughput improvement via power allocation and spectrum assignment and the proposed approaches are mostly model-based and dedicated to specific problem structures.Fortunately,with the trend of edge intelligence,complex resource management problems can be efficiently resolved in a model-free manner.In this paper,a joint beam activation,user-beam association and time resource allocation approach is proposed.The core idea is using stochastic learning at the ground station to identify active user-link beams to meet user rate demand.In addition,the convergence,optimality and complexity of our proposal are rigorously discussed.By simulation,it is shown that the rate goal of most of the users can be met and meanwhile satellite energy is saved owing to much less active beams.
文摘As the permeation of artificial intelligence(AI)in wireless applications,some data-driven and computing-intensive services are emerging,such as mobile high-definition AR/VR,and real-time fingertip interactions.Moreover,the application scenarios have been extended to penetrate the vertical industry,which have multi-dimension and diverse quality of service(QoS)requirements.Recently,the research and the development of 6G have been triggered,and much higher QoS requirements of data rate,latency,and connectivity will be raised.
基金This work was supported in part by the State Major Science and Technology Special Project(Grant No.2018ZX03001002-004 and 2018ZX03001023)the National Natural Science Foundation of China under No.61921003,61925101,61831002,and 61901044+1 种基金the Beijing Natural Science Foundation under No.JQ18016and the National Program for Special Support of Eminent Professionals.
文摘Intent-Based Networks(IBNs),which are originally proposed to introduce Artificial Intelligence(AI)into the sixth-generation(6G)wireless networks,can effectively solve the challenges of traditional networks in terms of efficiency,flexibility,and security.IBNs are mainly used to transform users’business intent into network configuration,operation,and maintenance strategies,which are prominent for designing the AI-enabled 6G networks.In particular,in order to meet the massive,intelligent service demands and overcome the time-varying radio propagation,IBNs can continuously learn and adapt to the time-varying network environment based on the massive collected network data in real-time.From the aspects of both the core network and radio access network,this article comprehensively surveys the architectures and key techniques of IBNs for 6G.In particular,the demonstration platforms of IBNs,such as the Apstra Operating System,Forward Networks Verification Platform,and One Convergence Service Interaction Platform,are presented.Moreover,the industrial development of IBNs is elaborated,including the emerging new products and startups to solve the problems of open data platforms,automated network operations,and preemptive network fault diagnosis.Finally,several open issues and challenges are identified as well to spur future researches.
文摘With Wireless communications in the 0.1-10TeraHertz(THz)band are envisioned as one of the key enablers towards ubiquitous wireless communications beyond 5G accommodating a massive number of connected devices and ultra-high user data rates in the order of Tera-bit-per-second.The THz band is located between the millimeter-wave(mmWave)and the far infrared(IR)band and still considered as one of the least investigated and exploited regions in the electromagnetic spectrum.
文摘The edge cache is an effective way to reduce the heavy traffic load and the end-to-end latency in radio access networks(RANs)for supporting a number of critical Internet of Things(IoT)services and applications.It has been verified to provide high spectral efficiency,high energy efficiency,and low latency.To exploit the advantages of edge cache,a paradigm of fog computing-based radio access networks(F-RANs)has emerged to provide great flexibility to satisfy quality-of-service requirements of various IoT applications in the fifth generation(5G)wireless systems.
文摘Driven by diverse intelligent applications,computing capability is moving from the central cloud to the edge of the network in the form of small cloud nodes,forming a distributed computing power network.Tasked with both packet transmission and data processing,it requires joint optimization of communications and computing.Considering the diverse requirements of applications,we develop a dynamic control policy of routing to determine both paths and computing nodes in a distributed computing power network.Different from traditional routing protocols,additional metrics related to computing are taken into consideration in the proposed policy.Based on the multi-attribute decision theory and the fuzzy logic theory,we propose two routing selection algorithms,the Fuzzy Logic-Based Routing(FLBR)algorithm and the low-complexity Pairwise Multi-Attribute Decision-Making(l PMADM)algorithm.Simulation results show that the proposed policy could achieve better performance in average processing delay,user satisfaction,and load balancing compared with existing works.
基金supported by Beijing Natural Science Foundation(Grant L182039),and National Natural Science Foundation of China(Grant 61971061).
文摘Although content caching and recommendation are two complementary approaches to improve the user experience,it is still challenging to provide an integrated paradigm to fully explore their potential,due to the high complexity and complicated tradeoff relationship.To provide an efficient management framework,the joint design of content delivery and recommendation in wireless content caching networks is studied in this paper.First,a joint transmission scheme of content objects and recommendation lists is designed with edge caching,and an optimization problem is formulated to balance the utility and cost of content caching and recommendation,which is an mixed integer nonlinear programming problem.Second,a reinforcement learning based algorithm is proposed to implement real time management of content caching,recommendation and delivery,which can approach the optimal solution without iterations during each decision epoch.Finally,the simulation results are provided to evaluate the performance of our proposed scheme,which show that it can achieve lower cost than the existing content caching and recommendation schemes.
