In mega-constellation Communication Systems, efficient routing algorithms and data transmission technologies are employed to ensure fast and reliable data transfer. However, the limited computational resources of sate...In mega-constellation Communication Systems, efficient routing algorithms and data transmission technologies are employed to ensure fast and reliable data transfer. However, the limited computational resources of satellites necessitate the use of edge computing to enhance secure communication.While edge computing reduces the burden on cloud computing, it introduces security and reliability challenges in open satellite communication channels. To address these challenges, we propose a blockchain architecture specifically designed for edge computing in mega-constellation communication systems. This architecture narrows down the consensus scope of the blockchain to meet the requirements of edge computing while ensuring comprehensive log storage across the network. Additionally, we introduce a reputation management mechanism for nodes within the blockchain, evaluating their trustworthiness, workload, and efficiency. Nodes with higher reputation scores are selected to participate in tasks and are appropriately incentivized. Simulation results demonstrate that our approach achieves a task result reliability of 95% while improving computational speed.展开更多
In LEO satellite communication networks,the number of satellites has increased sharply, the relative velocity of satellites is very fast, then electronic signal aliasing occurs from time to time. Those aliasing signal...In LEO satellite communication networks,the number of satellites has increased sharply, the relative velocity of satellites is very fast, then electronic signal aliasing occurs from time to time. Those aliasing signals make the receiving ability of the signal receiver worse, the signal processing ability weaker,and the anti-interference ability of the communication system lower. Aiming at the above problems, to save communication resources and improve communication efficiency, and considering the irregularity of interference signals, the underdetermined blind separation technology can effectively deal with the problem of interference sensing and signal reconstruction in this scenario. In order to improve the stability of source signal separation and the security of information transmission, a greedy optimization algorithm can be executed. At the same time, to improve network information transmission efficiency and prevent algorithms from getting trapped in local optima, delete low-energy points during each iteration process. Ultimately, simulation experiments validate that the algorithm presented in this paper enhances both the transmission efficiency of the network transmission system and the security of the communication system, achieving the process of interference sensing and signal reconstruction in the LEO satellite communication system.展开更多
Due to the mismatch of the circuit oscillators,there will always be a frequency offset between the transmitter and the receiver.In the adjacent channel interference(ACI)suppression system using the reconstruction and ...Due to the mismatch of the circuit oscillators,there will always be a frequency offset between the transmitter and the receiver.In the adjacent channel interference(ACI)suppression system using the reconstruction and cancellation method,the frequency offset decreases the accuracy of the reconstructed signal and introduces a time-varying term in the interference cancellation,resulting in poor performance of the ACI suppression.In this paper,the relationship between the normalized frequency offset,signal-to-noise ratio and the loss of interference suppression capability is analyzed through formula derivation and simulation.The validity of the frequency offset compensation method based on the pilot sequence is verified,and the relationship between the sequence length and the estimation accuracy is given.This paper provides necessary method reference and data support for the engineering of ACI suppression.展开更多
To overcome the inter-carrier interference(ICI) of orthogonal frequency division multiplexing(OFDM) systems subject to unknown carrier frequency offset(CFO) and multipath, this paper develops a blind adaptive interfer...To overcome the inter-carrier interference(ICI) of orthogonal frequency division multiplexing(OFDM) systems subject to unknown carrier frequency offset(CFO) and multipath, this paper develops a blind adaptive interference suppression scheme based on independent component analysis(ICA). Taking into account statistical independence of subcarriers' signals of OFDM, the signal recovery mechanism is investigated to achieve the goal of blind equalization. The received OFDM signals can be considered as the mixed observation signals. The effect of CFO and multipath corresponds to the mixing matrix in the problem of blind source separation(BSS) framework. In this paper, the ICAbased OFDM system model is built, and the proposed ICA-based detector is exploited to extract source signals from the observation of a received mixture based on the assumption of statistical independence between the sources. The blind separation technique can increase spectral efficiency and provide robustness performance against erroneous parameter estimation problem. Theoretical analysis and simulation results show that compared with the conventional pilot-based scheme, the improved performance of OFDM systems is obtained by the proposed ICA-based detection展开更多
Network slicing is envisioned as one of the key techniques to meet the extremely diversified service requirements of the Internet of Things(IoT)as it provides an enhanced user experience and elastic resource configura...Network slicing is envisioned as one of the key techniques to meet the extremely diversified service requirements of the Internet of Things(IoT)as it provides an enhanced user experience and elastic resource configuration.In the context of slicing enhanced IoT networks,both the Service Provider(SP)and Infrastructure Provider(InP)face challenges of ensuring efficient slice construction and high profit in dynamic environments.These challenges arise from randomly generated and departed slice requests from end-users,uncertain resource availability,and multidimensional resource allocation.Admission and resource allocation for distinct demands of slice requests are the key issues in addressing these challenges and should be handled effectively in dynamic environments.To this end,we propose an Opportunistic Admission and Resource allocation(OAR)policy to deal with the issues of random slicing requests,uncertain resource availability,and heterogeneous multi-resources.The key idea of OAR is to allow the SP to decide whether to accept slice requests immediately or defer them according to the load and price of resources.To cope with the random slice requests and uncertain resource availability,we formulated this issue as a Markov Decision Process(MDP)to obtain the optimal admission policy,with the aim of maximizing the system reward.Furthermore,the buyer-seller game theory approach was adopted to realize the optimal resource allocation,while motivating each SP and InP to maximize their rewards.Our numerical results show that the proposed OAR policy can make reasonable decisions effectively and steadily,and outperforms the baseline schemes in terms of the system reward.展开更多
In order to solve the high latency of traditional cloud computing and the processing capacity limitation of Internet of Things(IoT)users,Multi-access Edge Computing(MEC)migrates computing and storage capabilities from...In order to solve the high latency of traditional cloud computing and the processing capacity limitation of Internet of Things(IoT)users,Multi-access Edge Computing(MEC)migrates computing and storage capabilities from the remote data center to the edge of network,providing users with computation services quickly and directly.In this paper,we investigate the impact of the randomness caused by the movement of the IoT user on decision-making for offloading,where the connection between the IoT user and the MEC servers is uncertain.This uncertainty would be the main obstacle to assign the task accurately.Consequently,if the assigned task cannot match well with the real connection time,a migration(connection time is not enough to process)would be caused.In order to address the impact of this uncertainty,we formulate the offloading decision as an optimization problem considering the transmission,computation and migration.With the help of Stochastic Programming(SP),we use the posteriori recourse to compensate for inaccurate predictions.Meanwhile,in heterogeneous networks,considering multiple candidate MEC servers could be selected simultaneously due to overlapping,we also introduce the Multi-Arm Bandit(MAB)theory for MEC selection.The extensive simulations validate the improvement and effectiveness of the proposed SP-based Multi-arm bandit Method(SMM)for offloading in terms of reward,cost,energy consumption and delay.The results showthat SMMcan achieve about 20%improvement compared with the traditional offloading method that does not consider the randomness,and it also outperforms the existing SP/MAB based method for offloading.展开更多
As the demands of massive connections and vast coverage rapidly grow in the next wireless communication networks, rate splitting multiple access(RSMA) is considered to be the new promising access scheme since it can p...As the demands of massive connections and vast coverage rapidly grow in the next wireless communication networks, rate splitting multiple access(RSMA) is considered to be the new promising access scheme since it can provide higher efficiency with limited spectrum resources. In this paper, combining spectrum splitting with rate splitting, we propose to allocate resources with traffic offloading in hybrid satellite terrestrial networks. A novel deep reinforcement learning method is adopted to solve this challenging non-convex problem. However, the neverending learning process could prohibit its practical implementation. Therefore, we introduce the switch mechanism to avoid unnecessary learning. Additionally, the QoS constraint in the scheme can rule out unsuccessful transmission. The simulation results validates the energy efficiency performance and the convergence speed of the proposed algorithm.展开更多
High peak-to-average-power ratio(PAPR) and spectral leakage are two main drawbacks of multicarrier systems, such as in orthogonal frequency division multiplexing(OFDM), in future 5G wireless communications. For genera...High peak-to-average-power ratio(PAPR) and spectral leakage are two main drawbacks of multicarrier systems, such as in orthogonal frequency division multiplexing(OFDM), in future 5G wireless communications. For generating optimized wave forms for 5G communications, this paper proposes an iterative scheme combining time-domain N-continuous OFDM(TD-NC-OFDM) and serial peak cancellation(SPC). Based on the theory of projection onto convex sets(POCS), the effectiveness of the proposed scheme is proved, and the optimized time-frequency domain multicarrier waveforms are analyzed in terms of a balanced tradeoff between out-of-band spectral leakage and PAPR. Both theoretical analysis and simulation results show that the proposed scheme can jointly optimize both the PAPR and out-ofband radiation, with moderate computational complexity.展开更多
This paper presents a new Hard-Input Hard-Output (HIHO) iterative decoding algorithm for Turbo Product Codes (TPC), and especially describes the BCH-TPC codes aiming to alleviate error propagation and lower error floo...This paper presents a new Hard-Input Hard-Output (HIHO) iterative decoding algorithm for Turbo Product Codes (TPC), and especially describes the BCH-TPC codes aiming to alleviate error propagation and lower error floor. This algorithm mainly emp hasizes a decision mechanism for bit-flips, which thoroughly evaluates four different aspects of the decoding process, properly weighs and combines their respective reliability measures, and then employs the combined measure to make a judgment with regard to whether any particular bit should be flipped or not. Simulations result in a very steep Bit Error Rate (BER) curve indicating that a high-level net coding gain can be expected with a reasonable complexity. The simplicity and effectiveness of this HIHO decoding algorithm makes it a p romising candidate for the application in future high-speed fiber optical communications.展开更多
The ultra-dense network is a promising technology to increase the network capacity in the forthcoming fifthgeneration(5G)mobile communication networks by deploying lots of low power Small Base Stations(SBSs)which over...The ultra-dense network is a promising technology to increase the network capacity in the forthcoming fifthgeneration(5G)mobile communication networks by deploying lots of low power Small Base Stations(SBSs)which overlap with Macro Base Stations(MBSs).The interference and energy consumption increase rapidly with the number of SBSs although each SBS transmits with small power.In this paper,we model a downlink heterogeneous ultra-dense network where a lot of SBSs are randomly deployed with MBSs based on the Poisson point process.We derive the coverage probability and its variance,and analyze the area spectral efficiency and energy efficiency of the network considering three Fractional Power Control(FPC)strategies.The numerical results and Monte Carlo simulation results show that power control can mitigate the interference and balance the performances of inner-user and edge-user equipments.Especially,a great improvement of energy efficiency is archived with a little loss of area spectral efficiency when FPC is adopted.Finally,we analyze the effect of base stations’(BSs’)sleeping on the performance of the network when it is partially loaded.展开更多
Low power efficiency is a deficiency in traditional Orthogonal Frequency Division Multiplexing (OFDM) systems. To counter this problem, a new wireless transmission technology based on Zero-Padding Carrier Interferomet...Low power efficiency is a deficiency in traditional Orthogonal Frequency Division Multiplexing (OFDM) systems. To counter this problem, a new wireless transmission technology based on Zero-Padding Carrier Interferometry OFDM (ZP-CI/OFDM) is proposed. In a ZP-CI/OFDM system, transmission symbols are spread to all OFDM subcarriers via carrier interferometry codes. This reduces the Peak-to-Average Power Ratio (PAPR) that traditional OFDM suffers and also exploits frequency diversity gain. By zero-padding at the transmitter, advanced receiver technologies can be adopted for ZP-CI/OFDM so that frequency diversity gain can be further utilized and the power efficiency of the system is improved.展开更多
Orthogonal frequency division multiplex/offset QAM (OFDM/OQAM) and N-continuous OFDM are both improved multi-carrier modulation (MCM) techniques for the transmission of signals over multipath fading channels. In this ...Orthogonal frequency division multiplex/offset QAM (OFDM/OQAM) and N-continuous OFDM are both improved multi-carrier modulation (MCM) techniques for the transmission of signals over multipath fading channels. In this paper, we aim to compare these two techniques with respect to out-of-band radiation, bit error ratio (BER) and calculation complexity. Analysis and simulation results show that, compared to the N-continuous OFDM, the OFDM/OQAM has lower out-of-band radiation, calculation consumption and similar BER performance.展开更多
With the exponential growth of the data traffic in wireless communication systems, terahertz(THz) frequency band is envisioned as a promising candidate to support ultra-broadband for future beyond fifth generation(5G)...With the exponential growth of the data traffic in wireless communication systems, terahertz(THz) frequency band is envisioned as a promising candidate to support ultra-broadband for future beyond fifth generation(5G), bridging the gap between millimeter wave(mmWave) and optical frequency ranges. The purpose of this paper is to provide a comprehensive literature review on the development towards THz communications and presents some key technologies faced in THz wireless communication systems. Firstly, despite the substantial hardware problems that have to be developed in terms of the THz solid state superheterodyne receiver, high speed THz modulators and THz antennas, the practical THz channel model and the efficient THz beamforming are also described to compensate for the severe path attenuation. Moreover, two different kinds of lab-level THz communication systems are introduced minutely, named a solid state THz communication system and a spatial direct modulation THz communication system, respectively. The solid state THz system converts intermediate frequency(IF) modulated signal to THz frequency while the direct modulation THz system allows the high power THz sources to input for approving the relatively long distance communications. Finally, we discuss several potential application scenarios as well as some vital technical challenges that will be encountered in the future THz communications.展开更多
The problem of underdetermined blind source separation of adjacent satellite interference is proposed in this paper. Density Clustering algorithm(DC-algorithm) presented in this article is different from traditional m...The problem of underdetermined blind source separation of adjacent satellite interference is proposed in this paper. Density Clustering algorithm(DC-algorithm) presented in this article is different from traditional methods. Sparseness representation has been applied in underdetermined blind signal source separation. However, some difficulties have not been considered, such as the number of sources is unknown or the mixed matrix is ill-conditioned. In order to find out the number of the mixed signals, Short Time Fourier Transform(STFT) is employed to segment received mixtures. Then, we formulate the blind source signal as cluster problem. Furthermore, we construct Cost Function Pair and Decision Coordinate System by using density clustering. At the end of this paper, we discuss the performance of the proposed method and verify the novel method based on several simulations. We verify the proposed method on numerical experiments with real signal transmission, which demonstrates the validity of the proposed method.展开更多
This paper focuses on the cubature Kalman filters(CKFs) for the nonlinear dynamic systems with additive process and measurement noise. As is well known, the heart of the CKF is the third-degree spherical–radial cubat...This paper focuses on the cubature Kalman filters(CKFs) for the nonlinear dynamic systems with additive process and measurement noise. As is well known, the heart of the CKF is the third-degree spherical–radial cubature rule which makes it possible to compute the integrals encountered in nonlinear filtering problems. However, the rule not only requires computing the integration over an n-dimensional spherical region, but also combines the spherical cubature rule with the radial rule, thereby making it difficult to construct higher-degree CKFs. Moreover, the cubature formula used to construct the CKF has some drawbacks in computation. To address these issues, we present a more general class of the CKFs, which completely abandons the spherical–radial cubature rule. It can be shown that the conventional CKF is a special case of the proposed algorithm. The paper also includes a fifth-degree extension of the CKF. Two target tracking problems are used to verify the proposed algorithm. The results of both experiments demonstrate that the higher-degree CKF outperforms the conventional nonlinear filters in terms of accuracy.展开更多
Since the lower power requirement of code division multiple access(CDMA) than that of other multiple access, the CDMA technology is suitable to be used in low earth orbit(LEO) satellite communication system whose spac...Since the lower power requirement of code division multiple access(CDMA) than that of other multiple access, the CDMA technology is suitable to be used in low earth orbit(LEO) satellite communication system whose space power is limited due to the small size of satellite. The pilot channel of CDMA technology is very important for earth mobile station(EMS) in LEO system to recover carrier and code, but the power requirement of pilot channel is very higher than that of other channels. In this paper, a power reduction method for pilot channel is proposed. By the new method, the power of pilot channel transmitted from LEO satellite is reduced to a lower level. For improving the signal to noise ratio(SNR) of pilot channel with lower power, coherent integration is employed in EMS at the pre-processing stage. Considering the high dynamic situation of LEO satellite, the long period of time for integration will deteriorate the receiving performance of EMS, therefore, a dynamic compensation module is added to carrier tracking loop against the high dynamic. Meanwhile, the transfer function of the new tracking loop and the condition for steadystate zero error are deduced. Numerical examples are provided to demonstrate effectiveness of the proposed approach.展开更多
In intelligent transportation system(ITS), the interworking of vehicular networks(VN) and cellular networks(CN) is proposed to provide high-data-rate services to vehicles. As the network access quality for CN and VN i...In intelligent transportation system(ITS), the interworking of vehicular networks(VN) and cellular networks(CN) is proposed to provide high-data-rate services to vehicles. As the network access quality for CN and VN is location related, mobile data offloading(MDO), which dynamically selects access networks for vehicles, should be considered with vehicle route planning to further improve the wireless data throughput of individual vehicles and to enhance the performance of the entire ITS. In this paper, we investigate joint MDO and route selection for an individual vehicle in a metropolitan scenario. We aim to improve the throughput of the target vehicle while guaranteeing its transportation efficiency requirements in terms of traveling time and distance. To achieve this objective, we first formulate the joint route and access network selection problem as a semi-Markov decision process(SMDP). Then we propose an optimal algorithm to calculate its optimal policy. To further reduce the computation complexity, we derive a suboptimal algorithm which reduces the action space. Simulation results demonstrate that the proposed optimal algorithm significantly outperforms the existing work in total throughput and the late arrival ratio.Moreover, the heuristic algorithm is able to substantially reduce the computation time with only slight performance degradation.展开更多
N-continuous orthogonal frequency division multiplexing(NC-OFDM) is an outstanding method to suppress sidelobe for baseband OFDM signals in future 5G wireless communications.However,the precoder of NCOFDM usually caus...N-continuous orthogonal frequency division multiplexing(NC-OFDM) is an outstanding method to suppress sidelobe for baseband OFDM signals in future 5G wireless communications.However,the precoder of NCOFDM usually causes severe interference and high complexity.To alleviate these problems,this paper proposes an improved time-domain N-continuous OFDM(TD-NC-OFDM) by optimizing the smooth signal,which is the linear combination of rectangularly pulsed OFDM basis signals truncated by a smooth window.Furthermore,we show that the proposed scheme is with lower transceiver complexity and notable performance gain in signal-tointerference-plus-noise ratio(SINR).Lastly,simulation results show that the proposed low-interference TD-NC-OFDM can achieve similar sidelobe suppression performance,with negligible bit-error rate(BER) degradation,compared to conventional NC-OFDM.展开更多
In this paper,we co-design the transmission power and the offloading strategy for job offloading to a mobile edge computing(MEC)server at Terahertz(THz)frequencies.The goal is to minimize the communication energy cons...In this paper,we co-design the transmission power and the offloading strategy for job offloading to a mobile edge computing(MEC)server at Terahertz(THz)frequencies.The goal is to minimize the communication energy consumption while providing ultra-reliable low end-to-end latency(URLLC)services.To that end,we first establish a novel reliability framework,where the end-to-end(E2E)delay equals a weighted sum of the local computing delay,the communication delay and the edge computing delay,and the reliability is defined as the probability that the E2E delay remains below a certain pre-defined threshold.This reliability gives a full view of the statistics of the E2E delay,thus constituting advancement over prior works that have considered only average delays.Based on this framework,we establish the communication energy consumption minimization problem under URLLC constraints.This optimization problem is non-convex.To handle that issue,we first consider the special single-user case,where we derive the optimal solution by analyzing the structure of the optimization problem.Further,based on the analytical result for the single-user case,we decouple the optimization problem for multi-user scenarios into several sub-optimization problems and propose a sub-optimal algorithm to solve it.Numerical results verify the performance of the proposed algorithm.展开更多
With the successful demonstration of terahertz(THz)high-speed wireless data transmission,the THz frequencies are now becoming a worth candidate for post-5G wireless communications.On the other hand,to bring THz commun...With the successful demonstration of terahertz(THz)high-speed wireless data transmission,the THz frequencies are now becoming a worth candidate for post-5G wireless communications.On the other hand,to bring THz communications a step closer to real scenario application,solving high data rate realtime transmission is also an important issue.This paper describes a 220-GHz solid-state dual-carrier wireless link whose maximum transmission real-time data rates are 20.8 Gbps(10.4 Gbps per channel).By aggregating two carrier signals in the THz band,the contradiction between high real-time data rate communication and low sampling rate analog-to-digital(ADC)and digital-to-analog converter(DAC)is alleviated.The transmitting and receiving front-ends consist of 220-GHz diplexers,220-GHz sub-harmonic mixers based on anti-parallel Schottky barrier diodes,G-band low-noise amplifiers(LNA),WR-4.3 band high-gain Cassegrain antennas,high data rates dual-DAC and-ADC baseband platform and other components.The low-density parity-check(LDPC)encoding is also realized to improve the bit error rate(BER)of the received signal.Modulated signals are centered at 214.4 GHz and 220.6 GHz with-11.9 dBm and-13.4 dBm output power for channel 1 and 2,respectively.This link is demonstrated to achieve 20.8-Gbps real-time data transmission using 16-QAM modulation over a distance of 1030 m.The measured signal to noise ratio(SNR)is 17.3 dB and 16.5 dB,the corresponding BER is 8.6e-7 and 3.8e-7,respectively.Furthermore,4K video transmission is also carried out which is clear and free of stutter.The successful transmission of aggregated channels in this wireless link shows the great potential of THz communication for future wireless high-rate real-time data transmission applications.展开更多
基金supported in part by the National Natural Science Foundation of China under Grant No.U2268204,62172061 and 61871422National Key R&D Program of China under Grant No.2020YFB1711800 and 2020YFB1707900+2 种基金the Science and Technology Project of Sichuan Province under Grant No.2023ZHCG0014,2023ZHCG0011,2022YFG0155,2022YFG0157,2021GFW019,2021YFG0152,2021YFG0025,2020YFG0322Central Universities of Southwest Minzu University under Grant No.ZYN2022032,2023NYXXS034the State Scholarship Fund of the China Scholarship Council under Grant No.202008510081。
文摘In mega-constellation Communication Systems, efficient routing algorithms and data transmission technologies are employed to ensure fast and reliable data transfer. However, the limited computational resources of satellites necessitate the use of edge computing to enhance secure communication.While edge computing reduces the burden on cloud computing, it introduces security and reliability challenges in open satellite communication channels. To address these challenges, we propose a blockchain architecture specifically designed for edge computing in mega-constellation communication systems. This architecture narrows down the consensus scope of the blockchain to meet the requirements of edge computing while ensuring comprehensive log storage across the network. Additionally, we introduce a reputation management mechanism for nodes within the blockchain, evaluating their trustworthiness, workload, and efficiency. Nodes with higher reputation scores are selected to participate in tasks and are appropriately incentivized. Simulation results demonstrate that our approach achieves a task result reliability of 95% while improving computational speed.
基金supported by National Natural Science Foundation of China (62171390)Central Universities of Southwest Minzu University (ZYN2022032,2023NYXXS034)the State Scholarship Fund of the China Scholarship Council (NO.202008510081)。
文摘In LEO satellite communication networks,the number of satellites has increased sharply, the relative velocity of satellites is very fast, then electronic signal aliasing occurs from time to time. Those aliasing signals make the receiving ability of the signal receiver worse, the signal processing ability weaker,and the anti-interference ability of the communication system lower. Aiming at the above problems, to save communication resources and improve communication efficiency, and considering the irregularity of interference signals, the underdetermined blind separation technology can effectively deal with the problem of interference sensing and signal reconstruction in this scenario. In order to improve the stability of source signal separation and the security of information transmission, a greedy optimization algorithm can be executed. At the same time, to improve network information transmission efficiency and prevent algorithms from getting trapped in local optima, delete low-energy points during each iteration process. Ultimately, simulation experiments validate that the algorithm presented in this paper enhances both the transmission efficiency of the network transmission system and the security of the communication system, achieving the process of interference sensing and signal reconstruction in the LEO satellite communication system.
基金supported by the National Key R&D Program of China under grant 2018YFB1801903the National Natural Science Foundation of China under grants U19B2014,61771107,62071094,61701075,61601064,and 61531009。
文摘Due to the mismatch of the circuit oscillators,there will always be a frequency offset between the transmitter and the receiver.In the adjacent channel interference(ACI)suppression system using the reconstruction and cancellation method,the frequency offset decreases the accuracy of the reconstructed signal and introduces a time-varying term in the interference cancellation,resulting in poor performance of the ACI suppression.In this paper,the relationship between the normalized frequency offset,signal-to-noise ratio and the loss of interference suppression capability is analyzed through formula derivation and simulation.The validity of the frequency offset compensation method based on the pilot sequence is verified,and the relationship between the sequence length and the estimation accuracy is given.This paper provides necessary method reference and data support for the engineering of ACI suppression.
基金supported by a grant from the national High Technology Research and development Program of China(863 Program)(No.2012AA01A502)National Natural Science Foundation of China(No.61179006)Science and Technology Support Program of Sichuan Province(No.2014GZX0004)
文摘To overcome the inter-carrier interference(ICI) of orthogonal frequency division multiplexing(OFDM) systems subject to unknown carrier frequency offset(CFO) and multipath, this paper develops a blind adaptive interference suppression scheme based on independent component analysis(ICA). Taking into account statistical independence of subcarriers' signals of OFDM, the signal recovery mechanism is investigated to achieve the goal of blind equalization. The received OFDM signals can be considered as the mixed observation signals. The effect of CFO and multipath corresponds to the mixing matrix in the problem of blind source separation(BSS) framework. In this paper, the ICAbased OFDM system model is built, and the proposed ICA-based detector is exploited to extract source signals from the observation of a received mixture based on the assumption of statistical independence between the sources. The blind separation technique can increase spectral efficiency and provide robustness performance against erroneous parameter estimation problem. Theoretical analysis and simulation results show that compared with the conventional pilot-based scheme, the improved performance of OFDM systems is obtained by the proposed ICA-based detection
基金This work was supported in part by the Chongqing Technological Innovation and Application Development Projects under Grant cstc2019jscx-msxm1322,in part by the Zhejiang Lab under Grant 2021KF0AB03in part by the National Natural Science Foundation of China under Grant 62071091.
文摘Network slicing is envisioned as one of the key techniques to meet the extremely diversified service requirements of the Internet of Things(IoT)as it provides an enhanced user experience and elastic resource configuration.In the context of slicing enhanced IoT networks,both the Service Provider(SP)and Infrastructure Provider(InP)face challenges of ensuring efficient slice construction and high profit in dynamic environments.These challenges arise from randomly generated and departed slice requests from end-users,uncertain resource availability,and multidimensional resource allocation.Admission and resource allocation for distinct demands of slice requests are the key issues in addressing these challenges and should be handled effectively in dynamic environments.To this end,we propose an Opportunistic Admission and Resource allocation(OAR)policy to deal with the issues of random slicing requests,uncertain resource availability,and heterogeneous multi-resources.The key idea of OAR is to allow the SP to decide whether to accept slice requests immediately or defer them according to the load and price of resources.To cope with the random slice requests and uncertain resource availability,we formulated this issue as a Markov Decision Process(MDP)to obtain the optimal admission policy,with the aim of maximizing the system reward.Furthermore,the buyer-seller game theory approach was adopted to realize the optimal resource allocation,while motivating each SP and InP to maximize their rewards.Our numerical results show that the proposed OAR policy can make reasonable decisions effectively and steadily,and outperforms the baseline schemes in terms of the system reward.
基金This work was supported in part by the Zhejiang Lab under Grant 20210AB02in part by the Sichuan International Science and Technology Innovation Cooperation/Hong Kong,Macao and Taiwan Science and Technology Innovation Cooperation Project under Grant 2019YFH0163in part by the Key Research and Development Project of Sichuan Provincial Department of Science and Technology under Grant 2018JZ0071.
文摘In order to solve the high latency of traditional cloud computing and the processing capacity limitation of Internet of Things(IoT)users,Multi-access Edge Computing(MEC)migrates computing and storage capabilities from the remote data center to the edge of network,providing users with computation services quickly and directly.In this paper,we investigate the impact of the randomness caused by the movement of the IoT user on decision-making for offloading,where the connection between the IoT user and the MEC servers is uncertain.This uncertainty would be the main obstacle to assign the task accurately.Consequently,if the assigned task cannot match well with the real connection time,a migration(connection time is not enough to process)would be caused.In order to address the impact of this uncertainty,we formulate the offloading decision as an optimization problem considering the transmission,computation and migration.With the help of Stochastic Programming(SP),we use the posteriori recourse to compensate for inaccurate predictions.Meanwhile,in heterogeneous networks,considering multiple candidate MEC servers could be selected simultaneously due to overlapping,we also introduce the Multi-Arm Bandit(MAB)theory for MEC selection.The extensive simulations validate the improvement and effectiveness of the proposed SP-based Multi-arm bandit Method(SMM)for offloading in terms of reward,cost,energy consumption and delay.The results showthat SMMcan achieve about 20%improvement compared with the traditional offloading method that does not consider the randomness,and it also outperforms the existing SP/MAB based method for offloading.
文摘As the demands of massive connections and vast coverage rapidly grow in the next wireless communication networks, rate splitting multiple access(RSMA) is considered to be the new promising access scheme since it can provide higher efficiency with limited spectrum resources. In this paper, combining spectrum splitting with rate splitting, we propose to allocate resources with traffic offloading in hybrid satellite terrestrial networks. A novel deep reinforcement learning method is adopted to solve this challenging non-convex problem. However, the neverending learning process could prohibit its practical implementation. Therefore, we introduce the switch mechanism to avoid unnecessary learning. Additionally, the QoS constraint in the scheme can rule out unsuccessful transmission. The simulation results validates the energy efficiency performance and the convergence speed of the proposed algorithm.
基金supported in part by the National Science Foundation of China under Grant number 61471090the National HighTech R&D Program of China under Grant number 2014AA01A707+1 种基金the Fundamental Research Funds for the Central Universities(No.ZYGX2013J112)the Foundation Project of National Key Laboratory of Science and Technology on Communications under Grant 9140C020108140C02005
文摘High peak-to-average-power ratio(PAPR) and spectral leakage are two main drawbacks of multicarrier systems, such as in orthogonal frequency division multiplexing(OFDM), in future 5G wireless communications. For generating optimized wave forms for 5G communications, this paper proposes an iterative scheme combining time-domain N-continuous OFDM(TD-NC-OFDM) and serial peak cancellation(SPC). Based on the theory of projection onto convex sets(POCS), the effectiveness of the proposed scheme is proved, and the optimized time-frequency domain multicarrier waveforms are analyzed in terms of a balanced tradeoff between out-of-band spectral leakage and PAPR. Both theoretical analysis and simulation results show that the proposed scheme can jointly optimize both the PAPR and out-ofband radiation, with moderate computational complexity.
基金The authors would like to thank the editor and reviewer for helpful comments on the manuscripts. We also thank for the form support from Huawei Technology Corporations in this research. This work was partially supported by the National Natural Science Foundation of China under Grant No. 61101092.
文摘This paper presents a new Hard-Input Hard-Output (HIHO) iterative decoding algorithm for Turbo Product Codes (TPC), and especially describes the BCH-TPC codes aiming to alleviate error propagation and lower error floor. This algorithm mainly emp hasizes a decision mechanism for bit-flips, which thoroughly evaluates four different aspects of the decoding process, properly weighs and combines their respective reliability measures, and then employs the combined measure to make a judgment with regard to whether any particular bit should be flipped or not. Simulations result in a very steep Bit Error Rate (BER) curve indicating that a high-level net coding gain can be expected with a reasonable complexity. The simplicity and effectiveness of this HIHO decoding algorithm makes it a p romising candidate for the application in future high-speed fiber optical communications.
基金the Major Program of the National Nature Science Foundation of China(Grant No.61831004).
文摘The ultra-dense network is a promising technology to increase the network capacity in the forthcoming fifthgeneration(5G)mobile communication networks by deploying lots of low power Small Base Stations(SBSs)which overlap with Macro Base Stations(MBSs).The interference and energy consumption increase rapidly with the number of SBSs although each SBS transmits with small power.In this paper,we model a downlink heterogeneous ultra-dense network where a lot of SBSs are randomly deployed with MBSs based on the Poisson point process.We derive the coverage probability and its variance,and analyze the area spectral efficiency and energy efficiency of the network considering three Fractional Power Control(FPC)strategies.The numerical results and Monte Carlo simulation results show that power control can mitigate the interference and balance the performances of inner-user and edge-user equipments.Especially,a great improvement of energy efficiency is archived with a little loss of area spectral efficiency when FPC is adopted.Finally,we analyze the effect of base stations’(BSs’)sleeping on the performance of the network when it is partially loaded.
基金supported by the National Natural Science Foundation of China under Grant No.61071102
文摘Low power efficiency is a deficiency in traditional Orthogonal Frequency Division Multiplexing (OFDM) systems. To counter this problem, a new wireless transmission technology based on Zero-Padding Carrier Interferometry OFDM (ZP-CI/OFDM) is proposed. In a ZP-CI/OFDM system, transmission symbols are spread to all OFDM subcarriers via carrier interferometry codes. This reduces the Peak-to-Average Power Ratio (PAPR) that traditional OFDM suffers and also exploits frequency diversity gain. By zero-padding at the transmitter, advanced receiver technologies can be adopted for ZP-CI/OFDM so that frequency diversity gain can be further utilized and the power efficiency of the system is improved.
文摘Orthogonal frequency division multiplex/offset QAM (OFDM/OQAM) and N-continuous OFDM are both improved multi-carrier modulation (MCM) techniques for the transmission of signals over multipath fading channels. In this paper, we aim to compare these two techniques with respect to out-of-band radiation, bit error ratio (BER) and calculation complexity. Analysis and simulation results show that, compared to the N-continuous OFDM, the OFDM/OQAM has lower out-of-band radiation, calculation consumption and similar BER performance.
基金supported by the National High Technology Research and Development Program of China (863 program) of China under Grant No.2011AA010200 supported by the National Natural Science Foundation of China (NSFC) under Grant No.61771116 and No.91738102
文摘With the exponential growth of the data traffic in wireless communication systems, terahertz(THz) frequency band is envisioned as a promising candidate to support ultra-broadband for future beyond fifth generation(5G), bridging the gap between millimeter wave(mmWave) and optical frequency ranges. The purpose of this paper is to provide a comprehensive literature review on the development towards THz communications and presents some key technologies faced in THz wireless communication systems. Firstly, despite the substantial hardware problems that have to be developed in terms of the THz solid state superheterodyne receiver, high speed THz modulators and THz antennas, the practical THz channel model and the efficient THz beamforming are also described to compensate for the severe path attenuation. Moreover, two different kinds of lab-level THz communication systems are introduced minutely, named a solid state THz communication system and a spatial direct modulation THz communication system, respectively. The solid state THz system converts intermediate frequency(IF) modulated signal to THz frequency while the direct modulation THz system allows the high power THz sources to input for approving the relatively long distance communications. Finally, we discuss several potential application scenarios as well as some vital technical challenges that will be encountered in the future THz communications.
基金supported by a grant from the national High Technology Research and development Program of China (863 Program) (No.2012AA01A502)National Natural Science Foundation of China (No.61179006)Science and Technology Support Program of Sichuan Province(No.2014GZX0004)
文摘The problem of underdetermined blind source separation of adjacent satellite interference is proposed in this paper. Density Clustering algorithm(DC-algorithm) presented in this article is different from traditional methods. Sparseness representation has been applied in underdetermined blind signal source separation. However, some difficulties have not been considered, such as the number of sources is unknown or the mixed matrix is ill-conditioned. In order to find out the number of the mixed signals, Short Time Fourier Transform(STFT) is employed to segment received mixtures. Then, we formulate the blind source signal as cluster problem. Furthermore, we construct Cost Function Pair and Decision Coordinate System by using density clustering. At the end of this paper, we discuss the performance of the proposed method and verify the novel method based on several simulations. We verify the proposed method on numerical experiments with real signal transmission, which demonstrates the validity of the proposed method.
文摘This paper focuses on the cubature Kalman filters(CKFs) for the nonlinear dynamic systems with additive process and measurement noise. As is well known, the heart of the CKF is the third-degree spherical–radial cubature rule which makes it possible to compute the integrals encountered in nonlinear filtering problems. However, the rule not only requires computing the integration over an n-dimensional spherical region, but also combines the spherical cubature rule with the radial rule, thereby making it difficult to construct higher-degree CKFs. Moreover, the cubature formula used to construct the CKF has some drawbacks in computation. To address these issues, we present a more general class of the CKFs, which completely abandons the spherical–radial cubature rule. It can be shown that the conventional CKF is a special case of the proposed algorithm. The paper also includes a fifth-degree extension of the CKF. Two target tracking problems are used to verify the proposed algorithm. The results of both experiments demonstrate that the higher-degree CKF outperforms the conventional nonlinear filters in terms of accuracy.
基金supported by the National High Technology Research and Development Program of China (863 Program) (No.2012AA01A502)the National Natural Science Foundation of China (No.61179006)the Science and Technology Support Program of Sichuan Province (No.2014GZX0004)
文摘Since the lower power requirement of code division multiple access(CDMA) than that of other multiple access, the CDMA technology is suitable to be used in low earth orbit(LEO) satellite communication system whose space power is limited due to the small size of satellite. The pilot channel of CDMA technology is very important for earth mobile station(EMS) in LEO system to recover carrier and code, but the power requirement of pilot channel is very higher than that of other channels. In this paper, a power reduction method for pilot channel is proposed. By the new method, the power of pilot channel transmitted from LEO satellite is reduced to a lower level. For improving the signal to noise ratio(SNR) of pilot channel with lower power, coherent integration is employed in EMS at the pre-processing stage. Considering the high dynamic situation of LEO satellite, the long period of time for integration will deteriorate the receiving performance of EMS, therefore, a dynamic compensation module is added to carrier tracking loop against the high dynamic. Meanwhile, the transfer function of the new tracking loop and the condition for steadystate zero error are deduced. Numerical examples are provided to demonstrate effectiveness of the proposed approach.
基金the National Natural Science Foundation of China under Grants 61631005 and U1801261the National Key R&D Program of China under Grant 2018YFB1801105+3 种基金the Central Universities under Grant ZYGX2019Z022the Key Areas of Research and Development Program of Guangdong Province, China, under Grant 2018B010114001the 111 Project under Grant B20064the China Postdoctoral Science Foundation under Grant No. 2018M631075
文摘In intelligent transportation system(ITS), the interworking of vehicular networks(VN) and cellular networks(CN) is proposed to provide high-data-rate services to vehicles. As the network access quality for CN and VN is location related, mobile data offloading(MDO), which dynamically selects access networks for vehicles, should be considered with vehicle route planning to further improve the wireless data throughput of individual vehicles and to enhance the performance of the entire ITS. In this paper, we investigate joint MDO and route selection for an individual vehicle in a metropolitan scenario. We aim to improve the throughput of the target vehicle while guaranteeing its transportation efficiency requirements in terms of traveling time and distance. To achieve this objective, we first formulate the joint route and access network selection problem as a semi-Markov decision process(SMDP). Then we propose an optimal algorithm to calculate its optimal policy. To further reduce the computation complexity, we derive a suboptimal algorithm which reduces the action space. Simulation results demonstrate that the proposed optimal algorithm significantly outperforms the existing work in total throughput and the late arrival ratio.Moreover, the heuristic algorithm is able to substantially reduce the computation time with only slight performance degradation.
基金financial support of the National S&T Major Project(No.2014ZX03004003)the National Science Foundation of China under Grant number 61671134+1 种基金the open research fund of National Mobile Communications Research Laboratory,Southeast University (No.2015D09)the Fundamental Research Funds for the Central Universities(No. ZYGX2015J011) is gratefully acknowledged
文摘N-continuous orthogonal frequency division multiplexing(NC-OFDM) is an outstanding method to suppress sidelobe for baseband OFDM signals in future 5G wireless communications.However,the precoder of NCOFDM usually causes severe interference and high complexity.To alleviate these problems,this paper proposes an improved time-domain N-continuous OFDM(TD-NC-OFDM) by optimizing the smooth signal,which is the linear combination of rectangularly pulsed OFDM basis signals truncated by a smooth window.Furthermore,we show that the proposed scheme is with lower transceiver complexity and notable performance gain in signal-tointerference-plus-noise ratio(SINR).Lastly,simulation results show that the proposed low-interference TD-NC-OFDM can achieve similar sidelobe suppression performance,with negligible bit-error rate(BER) degradation,compared to conventional NC-OFDM.
文摘In this paper,we co-design the transmission power and the offloading strategy for job offloading to a mobile edge computing(MEC)server at Terahertz(THz)frequencies.The goal is to minimize the communication energy consumption while providing ultra-reliable low end-to-end latency(URLLC)services.To that end,we first establish a novel reliability framework,where the end-to-end(E2E)delay equals a weighted sum of the local computing delay,the communication delay and the edge computing delay,and the reliability is defined as the probability that the E2E delay remains below a certain pre-defined threshold.This reliability gives a full view of the statistics of the E2E delay,thus constituting advancement over prior works that have considered only average delays.Based on this framework,we establish the communication energy consumption minimization problem under URLLC constraints.This optimization problem is non-convex.To handle that issue,we first consider the special single-user case,where we derive the optimal solution by analyzing the structure of the optimization problem.Further,based on the analytical result for the single-user case,we decouple the optimization problem for multi-user scenarios into several sub-optimization problems and propose a sub-optimal algorithm to solve it.Numerical results verify the performance of the proposed algorithm.
基金the National Natural Science Foundation of China(NSFC)under Grant 91738102,Grant 61771116,and Grant 62022022。
文摘With the successful demonstration of terahertz(THz)high-speed wireless data transmission,the THz frequencies are now becoming a worth candidate for post-5G wireless communications.On the other hand,to bring THz communications a step closer to real scenario application,solving high data rate realtime transmission is also an important issue.This paper describes a 220-GHz solid-state dual-carrier wireless link whose maximum transmission real-time data rates are 20.8 Gbps(10.4 Gbps per channel).By aggregating two carrier signals in the THz band,the contradiction between high real-time data rate communication and low sampling rate analog-to-digital(ADC)and digital-to-analog converter(DAC)is alleviated.The transmitting and receiving front-ends consist of 220-GHz diplexers,220-GHz sub-harmonic mixers based on anti-parallel Schottky barrier diodes,G-band low-noise amplifiers(LNA),WR-4.3 band high-gain Cassegrain antennas,high data rates dual-DAC and-ADC baseband platform and other components.The low-density parity-check(LDPC)encoding is also realized to improve the bit error rate(BER)of the received signal.Modulated signals are centered at 214.4 GHz and 220.6 GHz with-11.9 dBm and-13.4 dBm output power for channel 1 and 2,respectively.This link is demonstrated to achieve 20.8-Gbps real-time data transmission using 16-QAM modulation over a distance of 1030 m.The measured signal to noise ratio(SNR)is 17.3 dB and 16.5 dB,the corresponding BER is 8.6e-7 and 3.8e-7,respectively.Furthermore,4K video transmission is also carried out which is clear and free of stutter.The successful transmission of aggregated channels in this wireless link shows the great potential of THz communication for future wireless high-rate real-time data transmission applications.
