Joint Subcarrier and Bit Allocation for Secondary User with Primary Users` Cooperation

( Xiaorong Xu ),( Yu-dong Yao ),( Sanqing Hu ),( Yingbiao Yao ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.12

Interference between primary user (PU) and secondary user (SU) transceivers should be mitigated in order to implement underlay spectrum sharing in cognitive radio networks (CRN). Considering this scenario, an improved joint subcarrier and bit allocation scheme for cognitive user with primary users` cooperation (PU Coop) in CRN is proposed. In this scheme, the optimization problem is formulated to minimize the average interference power level at the PU receiver via PU Coop, which guarantees a higher primary signal to interference plus noise ratio (SINR) while maintaining the secondary user total rate constraint. The joint optimal scheme is separated into subcarrier allocation and bit assignment in each subcarrier via arith-metric geo-metric (AM-GM) inequality with asymptotical optimization solution. Moreover, the joint subcarrier and bit optimization scheme, which is evaluated by the available SU subcarriers and the allocated bits, is analyzed in the proposed PU Coop model. The performance of cognitive spectral efficiency and the average interference power level are investigated. Numerical analysis indicates that the SU`s spectral efficiency increases significantly compared with the PU non-cooperation scenario. Moreover, the interference power level decreases dramatically for the proposed scheme compared with the traditional Hughes-Hartogs bit allocation scheme.

Joint Beamforming and Power Splitting Design for Physical Layer Security in Cognitive SWIPT Decode-and-Forward Relay Networks

( Xiaorong Xu ),( Andi Hu ),( Yingbiao Yao ),( Wei Feng ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.1

In an underlay cognitive simultaneous wireless information and power transfer (SWIPT) network, communication from secondary user (SU) to secondary destination (SD) is accomplished with decode-and-forward (DF) relays. Multiple energy-constrained relays are assumed to harvest energy from SU via power splitting (PS) protocol and complete SU secure information transmission with beamforming. Hence, physical layer security (PLS) is investigated in cognitive SWIPT network. In order to interfere with eavesdropper and improve relay’s energy efficiency, a destination-assisted jamming scheme is proposed. Namely, SD transmits artificial noise (AN) to interfere with eavesdropping, while jamming signal can also provide harvested energy to relays. Beamforming vector and power splitting ratio are jointly optimized with the objective of SU secrecy capacity maximization. We solve this non-convex optimization problem via a general two-stage procedure. Firstly, we obtain the optimal beamforming vector through semi-definite relaxation (SDR) method with a fixed power splitting ratio. Secondly, the best power splitting ratio can be obtained by one-dimensional search. We provide simulation results to verify the proposed solution. Simulation results show that the scheme achieves the maximum SD secrecy rate with appropriate selection of power splitting ratio, and the proposed scheme guarantees security in cognitive SWIPT networks.

Energy-efficient Buffer-aided Optimal Relay Selection Scheme with Power Adaptation and Inter-relay Interference Cancellation

( Xiaorong Xu ),( Liang Li ),( Yingbiao Yao ),( Xianyang Jiang ),( Sanqing Hu ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.11

Considering the tradeoff between energy consumption and outage behavior in buffer-aided relay selection, a novel energy-efficient buffer-aided optimal relay selection scheme with power adaptation and Inter-Relay Interference (IRI) cancellation is proposed. In the proposed scheme, energy consumption minimization is the objective with the consideration of relay buffer state, outage probability and relay power control, in order to eliminate IRI. The proposed scheme selects a pair of optimal relays from multiple candidate relays, denoted as optimal receive relay and optimal transmit relay respectively. Source-relay and relay-destination communications can be performed within a time-slot, which performs as Full-Duplex (FD) relaying. Markov chain model is applied to analyze the evolution of relay buffer states. System steady state outage probability and achievable diversity order are derived respectively. In addition, packet transmission delay and power reduction performance are investigated with a specific analysis. Numerical results show that the proposed scheme outperforms other relay selection schemes in terms of outage behavior with power adaptation and IRI cancellation in the same relay number and buffer size scenario. Compared with Buffer State relay selection method, the proposed scheme reduces transmission delay significantly with the same amount of relays. Average transmit power reduction can be implemented to relays with the increasing of relay number and buffer size, which realizes the tradeoff between energy-efficiency, outage behavior and delay performance in green cooperative communications.

Bidirectional Link Resource Allocation Strategy in GFDM-based Multiuser SWIPT Systems

( Xiaorong Xu ),( Minghang Sun ),( Wei-ping Zhu ),( Wei Feng ),( Yingbiao Yao ) 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.1

In order to enhance system energy efficiency, bidirectional link resource allocation strategy in GFDM-based multiuser SWIPT systems is proposed. In the downlink channel, each SWIPT user applies power splitting (PS) receiver structure in information decoding (ID) and non-linear energy harvesting (EH). In the uplink channel, information transmission power is originated from the harvested energy. An optimization problem is constructed to maximize weighted sum ID achievable rates in the downlink and uplink channels via bidirectional link power allocation as well as subcarriers and subsymbols scheduling. To solve this non-convex optimization problem, Lagrange duality method, sub-gradient-based method and greedy algorithm are adopted respectively. Simulation results show that the proposed strategy is superior to the fixed subcarrier scheme regardless of the weighting coefficients. It is superior to the heuristic algorithm in larger weighting coefficients scenario.

Optimal Relay Selection and Power Allocation in an Improved Low-Order-Bit Quantize-and-Forward Scheme

( Jianrong Bao ),( Dan He ),( Xiaorong Xu ),( Bin Jiang ),( Minhong Sun ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.11

Currently, the quantize-and-forward (QF) scheme with high order modulation and quantization has rather high complexity and it is thus impractical, especially in multiple relay cooperative communications. To overcome these deficiencies, an improved low complex QF scheme is proposed by the combination of the low order binary phase shift keying (BPSK) modulation and the 1-bit and 2-bit quantization, respectively. In this scheme, the relay selection is optimized by the best relay position for best bit-error-rate (BER) performance, where the relays are located closely to the destination node. In addition, an optimal power allocation is also suggested on a total power constraint. Finally, the BER and the achievable rate of the low order 1-bit, 2-bit and 3-bit QF schemes are simulated and analyzed. Simulation results indicate that the 3-bit QF scheme has about 1.8~5 dB, 4.5~7.5 dB and 1~2.5 dB performance gains than those of the decode-and-forward (DF), the 1-bit and 2-bit QF schemes, at BER of 10^-2, respectively. For the 2-bit QF, the scheme of the normalized Source-Relay (S-R) distance with 0.9 has about 5dB, 7.5dB, 9dB and 15dB gains than those of the distance with 0.7, 0.5, 0.3 and 0.1, respectively, at BER of 10^-3. In addition, the proposed optimal power allocation saves about 2.5dB much more relay power on an average than that of the fixed power allocation. Therefore, the proposed QF scheme can obtain excellent features, such as good BER performance, low complexity and high power efficiency, which make it much pragmatic in the future cooperative communications.

The influence of endogenous cathepsin in different subcellular fractions on the quality deterioration of Northern pike (Esox lucius) fillets during refrigeration and partial freezing storage

Hengheng Qiu,Xin Guo,Xiaorong Deng,Xiaobing Guo,Xiaoying Mao,Chengjian Xu,Jian Zhang 한국식품과학회 2020 Food Science and Biotechnology Vol.29 No.10

The purpose of this study was to investigate theendogenous cathepsin activity in each subcellular fractionand the effect of this activity on myofibrillar protein andtexture during refrigeration and partial freezing storage ofnorthern pike (Esox lucius) fillets. The results showed thatfillets stored under the refrigerated condition were moresusceptible to oxidation than partial freezing. Endogenouscathepsin activity indicated that partial freezing destroysthe integrity of lysosomes more effectively than refrigerationand inhibits the increase in cathepsin B and B ? L inlysosomes. The activity of cathepsin B and B ? L inlysosomes, mitochondria and myofibrils under the partialfreezing conditions was always lower than that underrefrigeration. Texture analysis showed that refrigerationhad a negative impact on hardness and springiness. Inconclusion, the cathepsin activity in each subcellularfraction was effectively inhibited and better textural characteristicswere obtained with partial freezing thanrefrigeration.

Comparative transcriptome analyses provide insights into the adaptation mechanisms to acute salt stresses in juvenile Sinonovacula constricta

Bin Ma,Zhaoshou Ran,Xiaorong Xu,Jilin Xu,Kai Liao,Jiayi Cao,Xiaojun Yan 한국유전학회 2019 Genes & Genomics Vol.41 No.5

Background Sinonovacula constricta is an economically important bivalve species in China, Korea and Japan that widely resides in estuarine and coastal areas where salinity fluctuates rapidly. However, little is known about its adaptation mechanisms to acute salt stresses. Objective To reveal the underlying molecular mechanisms involved in acute salt stresses in juvenile S. constricta. Methods Nine cDNA libraries (triplicate each trial) were established from juvenile S. constricta, which were subjected to low salinity (5 psu), optimal salinity (15 psu) and high salinity (25 psu) for 6 h, respectively. Results Illumina sequencing generated 478,587,310 clean reads totally, which were assembled into 427,057 transcripts of 246,672 unigenes. Compared with the control, 1259 and 2163 differentially expressed genes (DEGs) were identified under acute low and high salt stresses, respectively. GO and KEGG enrichment analyses of DEGs revealed that several key metabolic modulations were mainly responsible for the acute salt stresses. According to the significantly highlighted KEGG pathways, some key DEGs were identified and discussed in details. Notably, based on which, some potential osmolytes were further speculated. Conclusion Here, we carried out a unique report of comparative transcriptome analyses in juvenile S. constricta in response to acute salt stresses. The identified DEGs and their significantly enriched GO terms and KEGG pathways were critical for understanding and further investigating the underlying the physical and biochemical performances, and ultimately facilitated S. constricta breeding. Besides, the transcriptome data greatly enriched the genetic information of S. constricta, which were valuable for promoting its molecular biology researches.

Experimental verification of the effect of human lower extremity exoskeleton

Yang Li,Cheng Xu,Xiaorong Guan,Zhong Li,Huibin Li 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.8

A human lower extremity exoskeleton (HLEE) has been designed in our previous works, in which a simulation study has also been performed. However, verifying the effect of HLEE is still a problem. Accordingly, an experimental method combining a data collection system and a human motion capture system is proposed to solve this issue. Experimental data on the moment of momentum and energy provided to the HLEE knee joint and the knee joint angle deviation between the human body and HLEE exhibit good assistance effect. Moreover, the man-machine coordination and environmental suitability of the designed HLEE experimental prototype are validated in this study.

BtPDR: Bluetooth and PDR-Based Indoor Fusion Localization Using Smartphones

( Yingbiao Yao ),( Qiaojing Bao ),( Qi Han ),( Ruili Yao ),( Xiaorong Xu ),( Junrong Yan ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.8

This paper presents a Bluetooth and pedestrian dead reckoning (PDR)-based indoor fusion localization approach (BtPDR) using smartphones. A Bluetooth and PDR-based indoor fusion localization approach can localize the initial position of a smartphone with the received signal strength (RSS) of Bluetooth. While a smartphone is moving, BtPDR can track its position by fusing the localization results of PDR and Bluetooth RSS. In addition, BtPDR can adaptively modify the parameters of PDR. The contributions of BtPDR include: a Bluetooth RSS-based Probabilistic Voting (BRPV) localization mechanism, a probabilistic voting-based Bluetooth RSS and PDR fusion method, and a heuristic search approach for reducing the complexity of BRPV. The experiment results in a real scene show that the average positioning error is < 2m, which is considered adequate for indoor location-based service applications. Moreover, compared to the traditional PDR method, BtPDR improves the location accuracy by 42.6%, on average. Compared to state-of-the-art Wireless Local Area Network (WLAN) fingerprint + PDR-based fusion indoor localization approaches, BtPDR has better positioning accuracy and does not need the same offline workload as a fingerprint algorithm.