An Efficient Scheme to Achieve Differential Unitary Space-Time Modulation on MIMO-OFDM Systems

shouyin Liu,정정화 한국전자통신연구원 2004 ETRI Journal Vol.26 No.6

Differential unitary space-time modulation (DUSTM) has emerged as a promising technique to obtain spatial diversity without intractable channel estimation. This paper presents a study of the application of DUSTM on multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) systems with frequency-selective fading channels. From the view of a correlation analysis between subcarriers of OFDM, we obtain the maximum achievable diversity of DUSTM on MIMO-OFDM systems. Moreover, an efficient implementation strategy based on subcarrier reconstruction is proposed, which transmits all the signals of one signal matrix in one OFDM transmission and performs differential processing between two adjacent OFDM blocks. The proposed method is capable of obtaining both spatial and multipath diversity while reducing the effect of time variation of channels to a minimum. The performance improvement is confirmed by simulation results.

Improved Design Criterion for Space-Frequency Trellis Codes over MIMO-OFDM Systems

shouyin Liu,장정화 한국전자통신연구원 2004 ETRI Journal Vol.26 No.6

In this paper, we discuss the design problem and the robustness of space-frequency trellis codes (SFTCs) for multiple input multiple output, orthogonal frequency division multiplexing (MIMO-OFDM) systems. We find that the channel constructed by the consecutive subcarriers of an OFDM block is a correlated fading channel with the regular correlation function of the number and time delay of the multipaths. By introducing the first-order auto-regressive model, we decompose the correlated fading channel into two independent components: a slow fading channel and a fast fading channel. Therefore, the design problem of SFTCs is converted into the joint design in both slow fading and fast fading channels. We present an improved design criterion for SFTCs. We also show that the SFTCs designed according to our criterion are robust against the multipath time delays. Simulation results are provided to confirm our theoretic analysis.

Joint Antenna Selection and Multicast Precoding in Spatial Modulation Systems

Wei Liu,Xinxin Ma,Haoting Yan,Zhongnian Li,Shouyin Liu 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.11

In this paper, the downlink of the multicast based spatial modulation systems is investigated. Specifically, physical layer multicasting is introduced to increase the number of access users and to improve the communication rate of the spatial modulation system in which only single radio frequency chain is activated in each transmission. To minimize the bit error rate (BER) of the multicast based spatial modulation system, a joint optimizing algorithm of antenna selection and multicast precoding is proposed. Firstly, the joint optimization is transformed into a mixed-integer non-linear program based on single-stage reformulation. Then, a novel iterative algorithm based on the idea of branch and bound is proposed to obtain the quasi-optimal solution. Furthermore, in order to balance the performance and time complexity, a low-complexity deflation algorithm based on the successive convex approximation is proposed which can obtain a sub-optimal solution. Finally, numerical results are showed that the convergence of our proposed iterative algorithm is between 10 and 15 iterations and the signal-to-noise-ratio (SNR) of the iterative algorithm is 1-2dB lower than the exhaustive search based algorithm under the same BER accuracy conditions.

A Dynamical Hybrid CAC Scheme and Its Performance Analysis for Mobile Cellular Network with Multi-Service

( Jiping Li ),( Shixun Wu ),( Shouyin Liu ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.6

Call admission control (CAC) plays an important role in mobile cellular network to guarantee the quality of service (QoS). In this paper, a dynamic hybrid CAC scheme with integrated cutoff priority and handoff queue for mobile cellular network is proposed and some performance metrics are derived. The unique characteristic of the proposed CAC scheme is that it can support any number of service types and that the cutoff thresholds for handoff calls are dynamically adjusted according to the number of service types and service priority index. Moreover, timeouts of handoff calls in queues are also considered in our scheme. By modeling the proposed CAC scheme with a one-dimensional Markov chain (1DMC), some performance metrics are derived, which include new call blocking probability ( P_nb ) , forced termination probability (PF), average queue length, average waiting time in queue, offered traffic utilization, wireless channel utilization and system performance which is defined as the ratio of channel utilization to Grade of Service (GoS) cost function. In order to validate the correctness of the derived analytical performance metrics, simulation is performed. It is shown that simulation results match closely with the derived analytic results in terms of P_nb and PF. And then, to show the advantage of 1DMC modeling for the performance analysis of our proposed CAC scheme, the computing complexity of multi-dimensional Markov chain (MDMC) modeling in performance analysis is analyzed in detail. It is indicated that state-space cardinality, which reflects the computing complexity of MDMC, increases exponentially with the number of service types and total channels in a cell. However, the state-space cardinality of our 1DMC model for performance analysis is unrelated to the number of service types and is determined by total number of channels and queue capacity of the highest priority service in a cell. At last, the performance comparison between our CAC scheme and Mahmoud ASH`s scheme is carried out. The results show that our CAC scheme performs well to some extend.

Improved and Extended Range Scale Algorithm for Wireless Cellular Location

Shixun Wu,Jiping Li,Shouyin Liu,Jong-Wha Chong IEEE 2012 IEEE communications letters Vol.16 No.2

<P>The range scale algorithm (RSA) proposed in 2004 is a constrained optimization problem with only three base stations (BSs). In this letter, by introducing a new variable to replace the square term, the quadratic objective function of the constrained optimization problem in RSA is turned into a linear objective function. Then the computational complexity is reduced and the performance is improved. Moreover, when the number of BSs is larger than three, we construct a new objective function and give the corresponding constraints. So the RSA is extended for more BSs and the performance of positioning is improved significantly. Simulation results demonstrate that our proposed algorithms improve the location accuracy over traditional algorithms in different Non-line-of-sight (NLOS) environments.</P>

Dual Shift Invariant TOA Estimation Algorithm for Multi-Band Signals

Daegun Oh,Ying-chun Li,Shouyin Liu,Sang-Hun Yoon,Jong-Wha Chong IEEE 2012 IEEE communications letters Vol.16 No.10

<P>This letter proposes a dual shift invariant TOA estimation method for multi-band signals. Although conventional shift invariant TOA estimation methods have been proposed to exploit a single shift invariant structure of the transformed signals, the proposed method is developed to make use of the dual shift invariant structure of the transformed multi-band signals. The performance of the proposed method is compared with that of the Cramer-Rao lower bound (CRLB) and conventional algorithms such as MUSIC, matrix pencil, TLS-ESPRIT in additive white Gaussian noise (AWGN) and multipath channel.</P>

An Improved Two-Factor Mutual Authentication Scheme with Key Agreement in Wireless Sensor Networks

( Jiping Li ),( Yaoming Ding ),( Zenggang Xiong ),( Shouyin Liu ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.11

As a main component of Internet of Things (IoTs), the wireless sensor networks (WSNs) have been widely applied to various areas, including environment monitoring, health monitoring of human body, farming, commercial manufacture, reconnaissance mission in military, and calamity alert etc. Meanwhile, the privacy concerns also arise when the users are required to get the real-time data from the sensor nodes directly. To solve this problem, several user authentication and key agreement schemes with a smart card and a password have been proposed in the past years. However, these schemes are vulnerable to some attacks such as offline password guessing attack, user impersonation attack by using attacker’s own smart card, sensor node impersonation attack and gateway node bypassing attack. In this paper, we propose an improved scheme which can resist a wide variety of attacks in WSNs. Cryptanalysis and performance analysis show that our scheme can solve the weaknesses of previously proposed schemes and enhance security requirements while maintaining low computational cost.

RadioCycle: Deep Dual Learning based Radio Map Estimation

Yi Zheng,Tianqian Zhang,Cunyi Liao,Ji Wang,Shouyin Liu 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.11

The estimation of radio map (RM) is a fundamental and critical task for the network planning and optimization performance of mobile communication. In this paper, a RM estimation method is proposed based on a deep dual learning structure. This method can simultaneously and accurately reconstruct the urban building map (UBM) and estimate the RM of the whole cell by only part of the measured reference signal receiving power (RSRP). Our proposed method implements UBM reconstruction task and RM estimation task by constructing a dual U-Net-based structure, which is named RadioCycle. RadioCycle jointly trains two symmetric generators of the dual structure. Further, to solve the problem of interference negative transfer in generators trained jointly for two different tasks, RadioCycle introduces a dynamic weighted averaging method to dynamically balance the learning rate of these two generators in the joint training. Eventually, the experiments demonstrate that on the UBM reconstruction task, RadioCycle achieves an F1 score of 0.950, and on the RM estimation task, RadioCycle achieves a root mean square error of 0.069. Therefore, RadioCycle can estimate both the RM and the UBM in a cell with measured RSRP for only 20% of the whole cell.

An Efficient and Secure Authentication Scheme with Session Key Negotiation for Timely Application of WSNs

Jiping Li,Yuanyuan Zhang,Lixiang Shen,Jing Cao,Wenwu Xie,Yizheng,Shouyin Liu 한국인터넷정보학회 2024 KSII Transactions on Internet and Information Syst Vol.18 No.3

For Internet of Things, it is more preferred to have immediate access to environment information from sensor nodes (SNs) rather than from gateway nodes (GWNs). To fulfill the goal, mutual authentication scheme between user and SNs with session key (SK) negotiation is more suitable. However, this is a challenging task due to the constrained power, computation, communication and storage resources of SNs. Though lots of authentication schemes with SK negotiation have been designed to deal with it, they are still insufficiently secure and/or efficient, and some even have serious vulnerabilities. Therefore, we design an efficient secure authentication scheme with session key negotiation (eSAS2KN) for wireless sensor networks (WSNs) utilizing fuzzy extractor technique, hash function and bitwise exclusive-or lightweight operations. In the eSAS2KN, user and SNs are mutually authenticated with anonymity, and an SK is negotiated for their direct and instant communications subsequently. To prove the security of eSAS2KN, we give detailed informal security analysis, carry out logical verification by applying BAN logic, present formal security proof by employing Real-Or-Random (ROR) model, and implement formal security verification by using AVISPA tool. Finally, computation and communication costs comparison show the eSAS2kN is more efficient and secure for practical application.