Communications Theory

Session CT-02

Information Freshness and Codes

10:30 AM — 12:00 PM CST
Aug 10 Mon, 10:30 PM — 12:00 AM EDT

Closed-form Analysis of Age of Information in Energy Harvesting Network

Siyu Wang (Sun Yat-sen University, China); Xin Wang (Sun Yet-sen University, China); Tianyi Peng, Jiaxi Zhou, Qi Qin and Xijun Wang (Sun Yat-sen University, China)

We consider a system in which status updates are generated by a source node at will and are sent to a destination through a wireless channel. The energy consumption of transmission is linearly proportional to service time, which we modeled to be exponentially distributed. Due to the capacity limit of the battery and the vacancy of energy arrivals before the battery runs out, some of the status updates might possibly fail. We analyzed the Age of Information(AoI) for such a system, and show the efficacy of the system parameters on the AoI.

Age-Optimal UAV Trajectory Planning for Information Gathering with Energy Constraints

Xiangjin Zeng, Feipeng Ma, Tingwei Chen and Xuanzhang Chen (School of Electronics and Communication Engineering, Sun Yat-sen University, China); Xijun Wang (Sun Yat-sen University, China)

Many time-critical networks based on real-time information gathering by unmanned aerial vehicles (UAV) from a set of ground terminals. For those networks, minimization of the age of information (AoI), a metric proposed recently to measure the freshness of information, is of great importance. In this paper, we consider the problem of minimizing peak age, a metric of AoI, of a network composed of a mobile agent, a charging station and ground terminals. The agent's mobility is constrained by a graph G and energy constraints including battery capacity and charging rate. Aiming at this problem, we study Markov Process and solve it by dimensional reduction. We work out the theoretical minimum peak age under the constraints and propose the least-charging-timed Metropolis-Hastings trajectory, a semi-randomized trajectory proved to be theoretical optimal. Furthermore, we a heuristic trajectory named least-visit-time-based trajectory for the case that visit times for each ground terminal are available for the agent.

Cluster-Based Cooperative Digital Over-the-Air Aggregation for Wireless Federated Edge Learning

Ruichen Jiang and Sheng Zhou (Tsinghua University, China)

In this paper, we study a federated learning system at the wireless edge that uses over-the-air computation (Air-Comp). In such a system, users transmit their messages over a multi-access channel concurrently to achieve fast model aggregation. Recently, an AirComp scheme based on digital modulation has been proposed featuring one-bit gradient quantization and truncated channel inversion at users and a majority-voting based decoder at the fusion center (FC). We propose an improved digital AirComp scheme to relax its requirements on the transmitters, where the users perform phase correction and transmit with full power. To characterize the decoding failure probability at the FC, we introduce the normalized detection signal-to-noise ratio (SNR), which can be interpreted as the effective participation rate of the users. To mitigate wireless fading, we further propose a cluster-based system and design the relay selection scheme based on the normalized detection SNR. By local data fusion within each cluster and relay selection, our scheme can fully exploit the spatial diversity to increase the effective number of participating users and accelerate the model convergence.

Optimizing Information Freshness in Two-Way Relay Networks

Bohai Li (The University of Sydney, Australia); He Chen (The Chinese University of Hong Kong, Hong Kong); Nikolaos Pappas (Linkoping University, Sweden); Yonghui Li (University of Sydney, Australia)

In this paper, we investigate an amplify-and-forward (AF) based two-way cooperative status update system, where two sources aim to exchange status updates with each other as timely as possible with the help of a relay. Specifically, the relay receives the sum signal from the two sources in one time slot, and then amplifies and forwards the received signal to both the sources in the next time slot. We adopt a recently proposed concept, the age of information (AoI), to characterize the timeliness of the status updates. Assuming that the two sources are able to generate status updates at the beginning of each time slot (i.e., generate-at-will model), we derive a closed-form expression of the expected weighted sum AoI of the considered system. We further minimize the expected weighted sum AoI by optimizing the transmission power at each node under the peak power constraints. Simulation results corroborate the correctness of our theoretical analysis.

UEP Online Fountain Codes with Sequential Window Strategy

Yifan Duan and Lianghui Ding (Shanghai Jiao Tong University, China); Feng Yang (Shanghai Jiaotong University, China); Liang Qian and Cheng Zhi (Shanghai Jiao Tong University, China)

Online fountain code with Unequal Error Protection (UEP) has been proposed to provide better protection for the More Important Symbols (MISs) than that of the Less Important Symbols (LISs). However, the greater priority for MISs is accomplished substantially through choosing MISs with higher probability than that of LISs in encoding. Compared with normal online fountain code, this requires more code symbols to recover all symbols, which leads to high overhead. To reduce the overhead without affecting UEP performance, we propose a novel UEP online fountain codes scheme with sequential window strategy to provide best protection for LISs after decoding MISs in the completion phase. We have theoretically analyzed the upper bound on the overhead of the proposed UEP scheme and evaluated the performance by simulation. Both results show that the proposed scheme has lower overhead than another UEP online fountain codes scheme.

Session Chair

Xijun Wang, He Chen

Session CT-03

Communication Security

1:30 PM — 3:00 PM CST
Aug 11 Tue, 1:30 AM — 3:00 AM EDT

High Precision Indoor Positioning Method with Less Fingerprints Collection on 60GHz

Qiuna Niu (College of Information Science & Engineering, Ocean University of China, Qingdao, China); Hongping Li (College of Information Science & Engineering, Ocean University of China, Qingdao, China); Shi Wei (College of Information Science & Technology, Qingdao University of Science & Technology, Qingdao, China)

Facing huge demand for high precision indoor location services, an improved fingerprint-based positioning on 60GHz is proposed. Unlike conventional fingerprint methods, the algorithm adopts Time of Arrival (TOA)-based ranging values as location fingerprints due to high time resolution of 60GHz. To reduce the expense of fingerprint collection in the offline phrase, the fingerprints collection of the target location space is separated into two steps. In addition, the Gaussian Progress Regression (GPR) technique is applied to predict the missing ranging measurements. In the online phrase, sparse signal reconstruction algorithm based on Compressive Sensing (CS) is employed twice to achieve coarse and fine positioning. As the simulation results shown, the centimeter positioning accuracy can be obtained.

Achieving one-time pad via endogenous secret keys in wireless communication

Liang Jin (Zhengzhou Information Science and Technology Institution, China); Xu Wang (National Digital Switching System Engineering and Technological R&D Center, China); Yangming Lou (China National Digital Switching System Engineering and Technological R&D Center, China); Xiaoming Xu (National Digital Switching System Engineering & Technological Research Center, China)

The open and broadcast nature of wireless channels makes eavesdropping possible, leading to the endogenous problem of information leakage. Endogenous problems should be solved by endogenous security functions. Accordingly, wireless security problems should be resolved by channel-based endogenous security mechanisms. Firstly, this paper analyzes the endogenous security principle of the physical-layer-secret-key method. Afterward, we propose a novel conjecture that in a fast-fading environment, there must exist wireless systems where the endogenous secret key rate can match the user data rate. Moreover, the conjecture is well founded by the instantiation validation in a wireless system with BPSK input from the perspectives of both theoretical analysis and simulation experiments. These results indicate that it is possible to accomplish one-time pad via endogenous secret keys in wireless communication.

Achievable Rate of Multi-Antenna WSRNs with EH Constraint in the presence of a Jammer

Minhan Tian, Wangmei Guo, Guiguo Feng and Jingliang Gao (Xidian University, China)

In this paper, the rate-energy region is studied for the wireless sensor relay network (WSRN) with energy harvesting in the presence of a jammer. In the model, a source communicates to a destination equipped with a single antenna with energy harvesting constraint through a multi-antenna cooperative relay under beamforming. Meanwhile, there is a jammer intended to disturb the communication. The relay works in half-duplex mode and knows all the channel state information (CSI). When beamforming is employed at the relay, the network can be modeled as an equivalent Gaussian arbitrarily varying channel (GAVC). We characterize the achievable rate-energy region. Since the problem is non-convex, we present a stability method to transform it into a semi-definite programming problem (SDP), and the closed-form expression for two special boundary points of the rate-energy region is obtained. Finally, the simulations show the rate-energy region and the anti-jamming performance of the proposed scheme.

A Decode-and-Forward Relay-Aided Proactive Eavesdropping Scheme for Wireless Surveillance

Haowei Wu (Chongqing University, China); Lian Yan (School of Microelectronics and Communication Engineering, Chongqing University, China); Rui Ma (Chongqing University & Center of Communication and Tracking Telemetry Command, China); Jinglan Ou (Chongqing University, China); Jingyue Cui (School of Microelectronics and Communication Engineering, Chongqing University, China)

Legitimate wireless surveillance plays an important and preventive role in protecting public safety. To promote the eavesdropping performance of wireless surveillance systems, a proactive eavesdropping scheme with a decode-and-forward relay is proposed, where the relay intercepts suspicious information and interferes with the suspicious receiver simultaneously. The closed-form expressions are derived, including the decoding outage probability, eavesdropping outage probability, and average eavesdropping rate. To maximize the average eavesdropping rate, the transmit power and location deployment at the relay are optimized. Specifically, the closed-form result of approximate optimal transmit power for the relay is obtained, and the bisection-based algorithm is further proposed to verify its correctness. Simulation results validate that the proposed scheme achieves better eavesdropping performance than that without optimization.

Secrecy Rate Maximization in Millimeter Wave SWIPT Systems based on Non-Linear Energy Harvesting

Gangcan Sun (Zhengzhou University, China); Mengyuan Ma, Zhengyu Zhu, Jinlei Xu and Wanming Hao (Zhengzhou University, China)

In this paper, we study the secrecy rate maximization in millimeter-wave simultaneous wireless information and power transfer systems, where two radio frequency chain antenna architectures are considered. Then, a joint optimization problem of digital precoding vector, power splitting ratio and artificial noise covariance matrix is proposed, while non-linear energy harvesting and maximum transmit power constraint are considered. It is difficult to solve directly due to coupled variables and non-convexity, so we propose an alternating optimization algorithm based on semi-definite relaxation to solve it. Meanwhile, an alternating optimization algorithm based on zero forcing precoding is proposed to reduce the complexity. Finally, simulation results prove the validity of the proposed different algorithms.

Session Chair

Haowei Wu, Qiuna Niu

Session CT-04

Resource Allocation

3:10 PM — 4:40 PM CST
Aug 11 Tue, 3:10 AM — 4:40 AM EDT

Radio Resource Allocation for RAN Slicing in Mobile Networks

Liushan Zhou and Tiankui Zhang (Beijing University of Posts and Telecommunications, China); Jing Li (Network Technology Research Institute of China Unicom, China); Yutao Zhu (Beijing University of Posts and Telecommunications, China)

Network slicing is a key technology for addressing the issue of differentiated performance requirements of diversified services in mobile networks. We focus on the radio resource allocation for RAN slicing to ensure the isolation between slices, and improve radio resource utilization. This paper proposes a radio resource allocation algorithm for Service Level Agreement (SLA) contract rate maximization. Firstly, the business parameters in SLA are mapped to the measurable network performance metrics. Then, radio resources are allocated to network slices on the basis of the collected SLA requirements. Meanwhile, Radio resources of slices that do not meet the requirements are dynamically updated without affecting the performance of slices which has met the SLA requirements, to maximize the SLA contract rate of all slices. The simulation results show that the algorithm can achieve a better SLA contract rate on the premise of ensuring isolation between slices, additionally increase the number of service users.

Communication and Computation Resource Allocation for End-to-End Slicing in Mobile Networks

Zhou Tong, Tiankui Zhang and Yutao Zhu (Beijing University of Posts and Telecommunications, China); Rong Huang (Network Technology Research Institute of China Unicom, China)

In the mobile network, to better meet various vertical industries applications, network slicing is required in both the mobile core network and the access network to achieve end-to-end network slicing. This paper proposes a framework of end-to-end mobile network slicing. We model an end-to-end delay minimization problem based on the proposed framework. Then we propose a communication and computation resource joint allocation algorithm in end-to-end network slicing for ultra-reliable low-latency communication (URLLC). In the process of network slice orchestration and deployment, the virtual network function (VNF) mapping in the core network and the wireless resource allocation in the access network are jointly considered to minimize the end-to-end delay that ensures the reliability of the network slice. The simulation results show that the proposed algorithm can effectively reduce the end-to-end latency of network slicing, and guarantee the reliability requirements of network slicing as well.

Robust Design for signal mismatch with Steering Vector and Covariance Matrix Constraints

Junhui Qian, Shuya Zhang and Mengchen Lu (Chongqing University, China); Fengchun Tian (College of Communication Engineering£¬Chongqing University, China)

In this paper, a novel robust design algorithm for signal mismatch with steering vector and covariance matrix constraints is developed. The mismatched desired signal steering vector is estimated based on maximizing desired signal output power under the correlation coefficient constraint and norm constraint. The original nonconvex problem is proved belong to hidden convex, whose relaxation is tight, and can be solved by the relaxed semidefinite programming (SDP) method. Subsequently, the interference-plus-noise covariance matrix is further restructured with the shrinkage method and the subspace theorem based on the corrected steering vector, whose efficiency is analytically proven. Numerical experiments show that the proposed method gives satisfactory results under different scenarios.

Time-frequency Overlapped Signals Intelligent Modulation Recognition in Underlay CRN

Huaiyu Tang and Mingqian Liu (Xidian University, China); Liwei Chen (Luoyang Electronic Equipment Test Center of China, China); Jianying Li and Jian Chen (Xidian University, China)

In underlay cognitive radio networks (CRN), a novel intelligent modulation recognition method of time-frequency overlapped MPSK/MQAM signals based on convolutional neural network (CNN) is proposed in this paper. Aiming to achieve better modulation recognition performance of the time-frequency overlapped signals, the contour maps of cyclic spectrum of the received signals as the initial features are extracted, and then the CNN is used to extract further features as the final features. After preprocessing the contour maps to serve as input data for the CNN, the CNN is constructed and optimized to complete the training of the CNN. Finally, the well trained CNN is used for modulation recognition of the time-frequency overlapped MPSK/MQAM signals. Simulation results show that the average recognition rate of the proposed method is 90% when the signal-to-noise ratio (SNR) is 2dB, and it is robust to the power ratio and spectrum overlapped rate of the component signals.

Joint Optimization of Wireless Resource Allocation and Task Partition for Mobile Edge Computing

Zhuo Yang (Chongqing University, China); Jinfeng Xie (Chongqing Academy of Informatioon and Communications Technology, China); Jie Gao, Zhixiong Chen and Yunjian Jia (Chongqing University, China)

Mobile edge computing (MEC) is a promising technology to provide computing services for resource-constrained mobile users, improving the computing experience. However, energy consumption is also a considerable expense for users. In this paper, we investigate the joint wireless resource allocation, power control and computation offloading for a MEC-based multi-user wireless communication system. The objective of this paper is to minimize the energy consumption of all users. We formulate the problem as an optimization problem and propose to solve the optimal power control strategy by using convex optimization method. Then we derive the semi-closed forms of resource allocation and computation offloading. By using dichotomy algorithm, we have obtained the resource allocation and computation offloading policy. It is shown by simulation results that the proposed scheme can effectively reduce the energy consumption of users.

Session Chair

Junhui Qian, Yunjian Jia

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