Pub Date : 2020-12-01DOI: 10.1109/GLOBECOM42002.2020.9322545
Wendi Wang, Huarui Yin, Xiaohui Chen, Weidong Wang
In millimeter wave (mmWave) Multiple-Input Multiple-Output (MIMO) multiuser communication systems, Hybrid BeamForming (HBF) has been widely studied to make a balance between performance and hardware costs. However, the design of HBF requires either full Channel State Information (CSI) or the knowledge of equivalent channel, which brings heavy training and feedback overhead. In the paper, we propose a novel pure Analog BeamForming (ABF) method to reduce the training overhead and suppress the inter-user interference without digital beamforming. More specifically, we split the whole ABF process into two stages: standard beamforming at a special direction and spatial angle modulation. The former is realized by a common amplitude-weighted network shared by all links, while the latter is realized by a phase shifter network. Compared with the existing HBF methods, the proposed twostage ABF method does not require extra analog hardware components, and the digital beamforming process is removed. The training overhead of channel estimation can also be greatly reduced. Both theoretical analysis and numerical results show that this two-stage ABF method can outperform the HBF methods, especially in the medium and low SNR regime of pilot signals.
{"title":"Common amplitude-weighted analog beamforming in multiuser millimeter wave communication systems","authors":"Wendi Wang, Huarui Yin, Xiaohui Chen, Weidong Wang","doi":"10.1109/GLOBECOM42002.2020.9322545","DOIUrl":"https://doi.org/10.1109/GLOBECOM42002.2020.9322545","url":null,"abstract":"In millimeter wave (mmWave) Multiple-Input Multiple-Output (MIMO) multiuser communication systems, Hybrid BeamForming (HBF) has been widely studied to make a balance between performance and hardware costs. However, the design of HBF requires either full Channel State Information (CSI) or the knowledge of equivalent channel, which brings heavy training and feedback overhead. In the paper, we propose a novel pure Analog BeamForming (ABF) method to reduce the training overhead and suppress the inter-user interference without digital beamforming. More specifically, we split the whole ABF process into two stages: standard beamforming at a special direction and spatial angle modulation. The former is realized by a common amplitude-weighted network shared by all links, while the latter is realized by a phase shifter network. Compared with the existing HBF methods, the proposed twostage ABF method does not require extra analog hardware components, and the digital beamforming process is removed. The training overhead of channel estimation can also be greatly reduced. Both theoretical analysis and numerical results show that this two-stage ABF method can outperform the HBF methods, especially in the medium and low SNR regime of pilot signals.","PeriodicalId":12759,"journal":{"name":"GLOBECOM 2020 - 2020 IEEE Global Communications Conference","volume":"49 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90650170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1109/GLOBECOM42002.2020.9322307
Minghao Jiang, Yong Wang, Gaopeng Gou, Wei Cai, G. Xiong, Junzheng Shi
To prevent serious privacy leakage from website fingerprinting (WF) attacks, many traditional or adversarial WF defenses have been released. However, traditional WF defenses such as Walkie-Talkie (W-T) still generate patterns that might be captured by the deep learning (DL) based WF attacks, which are not effective. Adversarial perturbation based WF defenses better confuse WF attacks, but their requirements for the entire original traffic trace and perturbating any points including historical packets or cells of the network traffic are not practical. To deal with the effectiveness and practicality issues of existing defenses, we proposed a novel WF defense in this paper, called PST. Given a few past bursts of a trace as input, PST Predicts subsequent fuzzy bursts with a neural network, then Searches small but effective adversarial perturbation directions based on observed and predicted bursts, and finally Transfers the perturbation directions to the remaining bursts. Our experimental results over a public closed-world dataset demonstrate that PST can successfully break the network traffic pattern and achieve a high evasion rate of 87.6%, beating W-T by more than 31.59% at the same bandwidth overhead, with only observing 10 transferred bursts. Moreover, our defense adapts to WF attacks dynamically, which could be retrained or updated.
{"title":"PST: a More Practical Adversarial Learning-based Defense Against Website Fingerprinting","authors":"Minghao Jiang, Yong Wang, Gaopeng Gou, Wei Cai, G. Xiong, Junzheng Shi","doi":"10.1109/GLOBECOM42002.2020.9322307","DOIUrl":"https://doi.org/10.1109/GLOBECOM42002.2020.9322307","url":null,"abstract":"To prevent serious privacy leakage from website fingerprinting (WF) attacks, many traditional or adversarial WF defenses have been released. However, traditional WF defenses such as Walkie-Talkie (W-T) still generate patterns that might be captured by the deep learning (DL) based WF attacks, which are not effective. Adversarial perturbation based WF defenses better confuse WF attacks, but their requirements for the entire original traffic trace and perturbating any points including historical packets or cells of the network traffic are not practical. To deal with the effectiveness and practicality issues of existing defenses, we proposed a novel WF defense in this paper, called PST. Given a few past bursts of a trace as input, PST Predicts subsequent fuzzy bursts with a neural network, then Searches small but effective adversarial perturbation directions based on observed and predicted bursts, and finally Transfers the perturbation directions to the remaining bursts. Our experimental results over a public closed-world dataset demonstrate that PST can successfully break the network traffic pattern and achieve a high evasion rate of 87.6%, beating W-T by more than 31.59% at the same bandwidth overhead, with only observing 10 transferred bursts. Moreover, our defense adapts to WF attacks dynamically, which could be retrained or updated.","PeriodicalId":12759,"journal":{"name":"GLOBECOM 2020 - 2020 IEEE Global Communications Conference","volume":"6 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76988088","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1109/GLOBECOM42002.2020.9348241
Shimaa A. Mohamed, Sameh Sorour, H. Hassanein
A rapid increase has been lately noticed in the number of individual and groups of users offloading independent and inter-related computational tasks to mobile edge computing (MEC) servers, thus overloading them and increasing risks of service interruptions. In response to this issue, reactive service replication has been suggested to enable individual and groups of users to access services on remote edge servers, thus guaranteeing system scalability. In this paper, we propose a task offloading and service replication scheme on local and remote MEC servers, which minimizes the response time of all users while satisfying the delay requirements of user groups involved in same traffic-heavy and/or multimedia-intense applications (e.g., online gaming, multimedia conferencing, augmenting reality). We formulate the problem as an integer non-linear problem, and solve it using numerical solvers. We then compare the performance of our optimized solution with distance-based and resource-based greedy approaches. Simulation results show that our optimized solution can achieve up to 14% and 13% performance gains in comparison to these two greedy approaches, respectively.
{"title":"Group-Delay Aware Task Offloading with Service Replication for Scalable Mobile Edge Computing","authors":"Shimaa A. Mohamed, Sameh Sorour, H. Hassanein","doi":"10.1109/GLOBECOM42002.2020.9348241","DOIUrl":"https://doi.org/10.1109/GLOBECOM42002.2020.9348241","url":null,"abstract":"A rapid increase has been lately noticed in the number of individual and groups of users offloading independent and inter-related computational tasks to mobile edge computing (MEC) servers, thus overloading them and increasing risks of service interruptions. In response to this issue, reactive service replication has been suggested to enable individual and groups of users to access services on remote edge servers, thus guaranteeing system scalability. In this paper, we propose a task offloading and service replication scheme on local and remote MEC servers, which minimizes the response time of all users while satisfying the delay requirements of user groups involved in same traffic-heavy and/or multimedia-intense applications (e.g., online gaming, multimedia conferencing, augmenting reality). We formulate the problem as an integer non-linear problem, and solve it using numerical solvers. We then compare the performance of our optimized solution with distance-based and resource-based greedy approaches. Simulation results show that our optimized solution can achieve up to 14% and 13% performance gains in comparison to these two greedy approaches, respectively.","PeriodicalId":12759,"journal":{"name":"GLOBECOM 2020 - 2020 IEEE Global Communications Conference","volume":"33 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78061287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We consider the full-duplex operation with network coding in two-hop relay networks to enhance the throughput for block transmission of packets. We propose a low-complexity transmission scheme, which does not rely on channel state information (CSI), and hence can be easily implemented in practical systems. We derive a closed-form upper bound on the asymptotic throughput of the proposed scheme, and show that the derived upper bound is tighter than a general upper bound on the throughput of any transmission scheme even with perfect CSI. Simulation results show that, the proposed scheme actually performs close to the general upper bound, and in most cases it substantially outperforms the traditional uncoded Automatic Repeat-reQuest scheme which relies heavily on the ACK/NAK feedback for packet retransmission.
{"title":"Low-Complexity Coded Transmission Without CSI for Full-Duplex Relay Networks","authors":"Chao Chen, Zheng Meng, S. Baek, Xiaohan Yu, Chuanhuang Li, Rui Yin","doi":"10.1109/GLOBECOM42002.2020.9322444","DOIUrl":"https://doi.org/10.1109/GLOBECOM42002.2020.9322444","url":null,"abstract":"We consider the full-duplex operation with network coding in two-hop relay networks to enhance the throughput for block transmission of packets. We propose a low-complexity transmission scheme, which does not rely on channel state information (CSI), and hence can be easily implemented in practical systems. We derive a closed-form upper bound on the asymptotic throughput of the proposed scheme, and show that the derived upper bound is tighter than a general upper bound on the throughput of any transmission scheme even with perfect CSI. Simulation results show that, the proposed scheme actually performs close to the general upper bound, and in most cases it substantially outperforms the traditional uncoded Automatic Repeat-reQuest scheme which relies heavily on the ACK/NAK feedback for packet retransmission.","PeriodicalId":12759,"journal":{"name":"GLOBECOM 2020 - 2020 IEEE Global Communications Conference","volume":"93 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78096078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We consider the problem of intelligent and efficient task allocation mechanism in large-scale mobile edge computing (MEC), which can reduce delay and energy consumption in a parallel and distributed optimization. In this paper, we study the joint optimization model to consider cooperative task management mechanism among mobile terminals (MT), macro cell base station (MBS), and multiple small cell base station (SBS) for large-scale MEC applications. We propose a parallel multi-block Alternating Direction Method of Multipliers (ADMM) based method to model both requirements of low delay and low energy consumption in the MEC system which formulates the task allocation under those requirements as a nonlinear 0-1 integer programming problem. To solve the optimization problem, we develop an efficient combination of conjugate gradient, Newton and linear search techniques based algorithm with Logarithmic Smoothing (for global variables updating) and the Cyclic Block coordinate Gradient Projection (CBGP, for local variables updating) methods, which can guarantee convergence and reduce computational complexity with a good scalability. Numerical results demonstrate the effectiveness of the proposed mechanism and it can effectively reduce delay and energy consumption for a large-scale MEC system.
{"title":"A Task Allocation Framework for Large-Scale Mobile Edge Computing","authors":"Xinghan Wang, Xiaoxiong Zhong, Yanbin Zheng, Xiaoke Ma, Tingting Yang, Genglin Zhang","doi":"10.1109/GLOBECOM42002.2020.9322222","DOIUrl":"https://doi.org/10.1109/GLOBECOM42002.2020.9322222","url":null,"abstract":"We consider the problem of intelligent and efficient task allocation mechanism in large-scale mobile edge computing (MEC), which can reduce delay and energy consumption in a parallel and distributed optimization. In this paper, we study the joint optimization model to consider cooperative task management mechanism among mobile terminals (MT), macro cell base station (MBS), and multiple small cell base station (SBS) for large-scale MEC applications. We propose a parallel multi-block Alternating Direction Method of Multipliers (ADMM) based method to model both requirements of low delay and low energy consumption in the MEC system which formulates the task allocation under those requirements as a nonlinear 0-1 integer programming problem. To solve the optimization problem, we develop an efficient combination of conjugate gradient, Newton and linear search techniques based algorithm with Logarithmic Smoothing (for global variables updating) and the Cyclic Block coordinate Gradient Projection (CBGP, for local variables updating) methods, which can guarantee convergence and reduce computational complexity with a good scalability. Numerical results demonstrate the effectiveness of the proposed mechanism and it can effectively reduce delay and energy consumption for a large-scale MEC system.","PeriodicalId":12759,"journal":{"name":"GLOBECOM 2020 - 2020 IEEE Global Communications Conference","volume":"29 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78218948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1109/GLOBECOM42002.2020.9348102
D. Galappaththige, Dhanushka Kudathanthirige, Gayan Amarasuriya
In this paper, the performance of a distributed intelligent reflective surface (IRS)-aided communication system is investigated. To this end, the optimal signal-to-noise ratio (SNR) achievable through the direct and reflected channels is quantified by controlling the phase-shifts of the distributed IRS. This optimal SNR is statistically characterized by deriving tight approximations to the exact probability density function and cumulative distribution function for Nakagami-$m$ fading. Thereby, the outage probability and achievable rate bounds are derived in closed-form, and they are validated via Monte-Carlo simulations. Our numerical results reveal that the distributed IRS-aided communication set-ups can boost the outage and rate performance of wireless systems.
{"title":"Performance Analysis of Distributed Intelligent Reflective Surface Aided Communications","authors":"D. Galappaththige, Dhanushka Kudathanthirige, Gayan Amarasuriya","doi":"10.1109/GLOBECOM42002.2020.9348102","DOIUrl":"https://doi.org/10.1109/GLOBECOM42002.2020.9348102","url":null,"abstract":"In this paper, the performance of a distributed intelligent reflective surface (IRS)-aided communication system is investigated. To this end, the optimal signal-to-noise ratio (SNR) achievable through the direct and reflected channels is quantified by controlling the phase-shifts of the distributed IRS. This optimal SNR is statistically characterized by deriving tight approximations to the exact probability density function and cumulative distribution function for Nakagami-$m$ fading. Thereby, the outage probability and achievable rate bounds are derived in closed-form, and they are validated via Monte-Carlo simulations. Our numerical results reveal that the distributed IRS-aided communication set-ups can boost the outage and rate performance of wireless systems.","PeriodicalId":12759,"journal":{"name":"GLOBECOM 2020 - 2020 IEEE Global Communications Conference","volume":"28 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78233003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1109/GLOBECOM42002.2020.9322558
Yufan Huang, Richeng Jin, H. Dai
Recent advances in social media and information technology have enabled much faster dissemination of information, while at the same time raise concerns about privacy leakage after various privacy breaches. Therefore, the privacy guarantees of information dissemination protocols have attracted increasing research interests, among which the gossip protocols assume vital importance in various information exchange applications. Very recently, the rigorous framework of differential privacy has been introduced to measure the privacy guarantees of gossip protocols in the simplified complete network scenario. In this work, we extend the study to general networks. First, lower bounds of the differential privacy guarantees are derived for the gossip protocols in general networks in both synchronous and asynchronous settings. The prediction uncertainty of the source node given a uniform prior is also determined. It is found that source anonymity is closely related to some key network structure parameters in the general network setting. Then, we investigate information spreading in wireless networks with unreliable communications, and quantity the tradeoff between differential privacy guarantees and information spreading efficiency. Finally, considering that the attacker may not be present in the beginning of the information dissemination process, the scenario of delayed monitoring is studied and the corresponding differential privacy guarantees are evaluated.
{"title":"Differential Privacy and Prediction Uncertainty of Gossip Protocols in General Networks","authors":"Yufan Huang, Richeng Jin, H. Dai","doi":"10.1109/GLOBECOM42002.2020.9322558","DOIUrl":"https://doi.org/10.1109/GLOBECOM42002.2020.9322558","url":null,"abstract":"Recent advances in social media and information technology have enabled much faster dissemination of information, while at the same time raise concerns about privacy leakage after various privacy breaches. Therefore, the privacy guarantees of information dissemination protocols have attracted increasing research interests, among which the gossip protocols assume vital importance in various information exchange applications. Very recently, the rigorous framework of differential privacy has been introduced to measure the privacy guarantees of gossip protocols in the simplified complete network scenario. In this work, we extend the study to general networks. First, lower bounds of the differential privacy guarantees are derived for the gossip protocols in general networks in both synchronous and asynchronous settings. The prediction uncertainty of the source node given a uniform prior is also determined. It is found that source anonymity is closely related to some key network structure parameters in the general network setting. Then, we investigate information spreading in wireless networks with unreliable communications, and quantity the tradeoff between differential privacy guarantees and information spreading efficiency. Finally, considering that the attacker may not be present in the beginning of the information dissemination process, the scenario of delayed monitoring is studied and the corresponding differential privacy guarantees are evaluated.","PeriodicalId":12759,"journal":{"name":"GLOBECOM 2020 - 2020 IEEE Global Communications Conference","volume":"25 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75427487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1109/GLOBECOM42002.2020.9347981
A. Mostafa, V. Wong
Backscatter communication is a promising technology for energy-efficient communications. It enables the Internet of things (IoT) devices to send their data by backscattering and modulating the incident radio frequency (RF) signals. In this paper, we propose a scheme for improving the connection density of backscatter communication systems, i.e., increasing the number of backscattering-enabled IoT devices that meet a minimum threshold of the received signal-to-noise ratio (SNR) at the serving base station (BS). The aforementioned goal is achieved by allowing the user equipment (UE) devices to relay the backscattered signals from the IoT devices. A UE superimposes its own uplink data with the data from an associated IoT device using power-domain non-orthogonal multiple access (NOMA). Since the UEs are mobile and have higher transmit power, the IoT devices utilize the nearby UEs to relay their data. In addition, using UEs as relays helps the BS to support more backscattering-enabled IoT devices. We formulate the connection density maximization problem to pair the IoT devices with the available UE relays. The formulated problem is a mixed-integer linear programming (MILP) problem. Although the formulated problem can be solved optimally, it has an exponential complexity. Hence, we propose a suboptimal algorithm which decomposes the original problem into smaller subproblems that can be solved by low complexity algorithms. Simulation results show that the proposed scheme with UEs as relays can increase the connection density by up to 65% compared to deploying fixed relays.
{"title":"Connection Density Enhancement of Backscatter Communication Systems with Relaying","authors":"A. Mostafa, V. Wong","doi":"10.1109/GLOBECOM42002.2020.9347981","DOIUrl":"https://doi.org/10.1109/GLOBECOM42002.2020.9347981","url":null,"abstract":"Backscatter communication is a promising technology for energy-efficient communications. It enables the Internet of things (IoT) devices to send their data by backscattering and modulating the incident radio frequency (RF) signals. In this paper, we propose a scheme for improving the connection density of backscatter communication systems, i.e., increasing the number of backscattering-enabled IoT devices that meet a minimum threshold of the received signal-to-noise ratio (SNR) at the serving base station (BS). The aforementioned goal is achieved by allowing the user equipment (UE) devices to relay the backscattered signals from the IoT devices. A UE superimposes its own uplink data with the data from an associated IoT device using power-domain non-orthogonal multiple access (NOMA). Since the UEs are mobile and have higher transmit power, the IoT devices utilize the nearby UEs to relay their data. In addition, using UEs as relays helps the BS to support more backscattering-enabled IoT devices. We formulate the connection density maximization problem to pair the IoT devices with the available UE relays. The formulated problem is a mixed-integer linear programming (MILP) problem. Although the formulated problem can be solved optimally, it has an exponential complexity. Hence, we propose a suboptimal algorithm which decomposes the original problem into smaller subproblems that can be solved by low complexity algorithms. Simulation results show that the proposed scheme with UEs as relays can increase the connection density by up to 65% compared to deploying fixed relays.","PeriodicalId":12759,"journal":{"name":"GLOBECOM 2020 - 2020 IEEE Global Communications Conference","volume":"42 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75574814","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1109/GLOBECOM42002.2020.9322448
Zefeng Qi, Guobing Li, Shiyu Zhai, Guomei Zhang
In this paper the topology learning for time-varying graph signals with incremental data is studied. In order to learn the topology which is slowly time-varying during data collection, we separate the data of observation into multiple groups by time, and for each group we model the topology learning as a sparse optimization problem, in which the penalty function is designed to consider both the incremental data and previous topology information for graph learning. Moreover, a correction function for dynamic topology is developed by considering a priori information of topology changes. Based on that, by solving the optimization problem we then propose a dynamic topology learning and tracking algorithm to learn as well as track the varying graph topology. Simulations on synthetic and real-world dataset are performed to reveal the performance gain of the proposed algorithm.
{"title":"Incremental Data-Driven Topology Learning for Time-Varying Graph Signals","authors":"Zefeng Qi, Guobing Li, Shiyu Zhai, Guomei Zhang","doi":"10.1109/GLOBECOM42002.2020.9322448","DOIUrl":"https://doi.org/10.1109/GLOBECOM42002.2020.9322448","url":null,"abstract":"In this paper the topology learning for time-varying graph signals with incremental data is studied. In order to learn the topology which is slowly time-varying during data collection, we separate the data of observation into multiple groups by time, and for each group we model the topology learning as a sparse optimization problem, in which the penalty function is designed to consider both the incremental data and previous topology information for graph learning. Moreover, a correction function for dynamic topology is developed by considering a priori information of topology changes. Based on that, by solving the optimization problem we then propose a dynamic topology learning and tracking algorithm to learn as well as track the varying graph topology. Simulations on synthetic and real-world dataset are performed to reveal the performance gain of the proposed algorithm.","PeriodicalId":12759,"journal":{"name":"GLOBECOM 2020 - 2020 IEEE Global Communications Conference","volume":"35 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77937783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2020-12-01DOI: 10.1109/GLOBECOM42002.2020.9322378
A. Fawzy, Sumei Sun, Teng Joon Lim, Yong-xin Guo, P. Tan
A practical power amplifier (PA) has nonlinear characteristics that distort the output signal and hence increase the transmission error. Digital pre-distortion (DPD) has been widely accepted to compensate for the PA nonlinearity. However, in direct-conversion transmitters (DCTs), DPD performance is affected by in-phase and quadrature (IQ) imbalance. In this paper, we utilize the Iterative Learning Control (ILC) algorithm to design a DPD scheme to compensate for PA nonlinearity under IQ imbalance. We first prove that ILC is applicable in such a scenario. This proof is validated using simulations which show that ILC is able to estimate the PA ideal input. The estimated ideal input is then exploited in training a neural network (NN)-based DPD model. We provide the complexity estimation of our proposed scheme using the number of real multiplications. Finally, we demonstrate the performance advantage of our proposed scheme in comparison with other existing polynomial based approaches through simulations and measurements.
{"title":"Iterative Learning Control for Pre-distortion Design in Wideband Direct-Conversion Transmitters","authors":"A. Fawzy, Sumei Sun, Teng Joon Lim, Yong-xin Guo, P. Tan","doi":"10.1109/GLOBECOM42002.2020.9322378","DOIUrl":"https://doi.org/10.1109/GLOBECOM42002.2020.9322378","url":null,"abstract":"A practical power amplifier (PA) has nonlinear characteristics that distort the output signal and hence increase the transmission error. Digital pre-distortion (DPD) has been widely accepted to compensate for the PA nonlinearity. However, in direct-conversion transmitters (DCTs), DPD performance is affected by in-phase and quadrature (IQ) imbalance. In this paper, we utilize the Iterative Learning Control (ILC) algorithm to design a DPD scheme to compensate for PA nonlinearity under IQ imbalance. We first prove that ILC is applicable in such a scenario. This proof is validated using simulations which show that ILC is able to estimate the PA ideal input. The estimated ideal input is then exploited in training a neural network (NN)-based DPD model. We provide the complexity estimation of our proposed scheme using the number of real multiplications. Finally, we demonstrate the performance advantage of our proposed scheme in comparison with other existing polynomial based approaches through simulations and measurements.","PeriodicalId":12759,"journal":{"name":"GLOBECOM 2020 - 2020 IEEE Global Communications Conference","volume":"75 1","pages":"1-6"},"PeriodicalIF":0.0,"publicationDate":"2020-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77973079","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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