A Proactive Dynamic Spectrum Access Method against both Erroneous Spectrum Sensing and Asynchronous Inter-Channel Spectrum Sensing

( Junrong Gu ),( Sung Jeen Jang ),( Jae Moung Kim ) 한국인터넷정보학회 2012 KSII Transactions on Internet and Information Syst Vol.6 No.1

Most of the current frequency hopping (FH) based dynamic spectrum access (DSA) methods concern a reactive channel access scheme with synchronous inter-channel spectrum sensing, i.e., FH is reactively triggered by the primary user (PU)`s return reported by spectrum sensing, and the PU channel to be switched to is assumed precisely just sensed or ready to be sensed, as if the inter-channel spectrum sensing moments are synchronous. However, the inter-channel spectrum sensing moments are more likely to be asynchronous, which risks PU suffering more interference. Moreover, the spectrum sensing is usually erroneous, which renders the problem more complex. To address this problem, we propose a proactive FH based DSA method against both erroneous spectrum sensing and asynchronous inter-channel spectrum sensing (moments). We term it as proactive DSA. The optimal FH sequence is obtained by dynamic programming. The complexity is also analyzed. Finally, the simulation results confirm the effectiveness of the proposed method.

Optimal Power Allocation in an 'Off' Spectrum Sensing Interval for Cognitive Radio

Junrong Gu,Wha Sook Jeon IEEE 2013 IEEE COMMUNICATIONS LETTERS Vol.17 No.10

<P>Most of the current works about cognitive radio favor a constant power allocation policy during an 'off' spectrum sensing interval, which is the time between two spectrum sensing activities when the outcome of the first spectrum sensing indicates 'off'. However, according to our work, this policy becomes suboptimal with respect to bit error rate minimization, when the traffics of primary user follow an alternating renewal process. Therefore, under this scenario, we suggest the optimal power allocation policy, by solving a convex optimization problem on power allocation of secondary user. Our results provide meaningful insight into the design of transmitting schemes for cognitive radio.</P>

Experimental investigation of surfactant enhanced spontaneous imbibition in Chinese shale oil reservoirs using NMR tests

Junrong Liu,James J. Sheng 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.72 No.-

Surfactant enhanced spontaneous imbibition is an effective method to enhance oil recovery in shalereservoirs, however the mechanism is still unclear. This work attempts to investigate the effect of addedsurfactants on the spontaneous imbibition into shale rocks using NMR tests. Contact angles and IFT aremeasured to evaluate the efficiency of different surfactants in terms of wettability alteration and IFTreduction. According to the experimental results, the studied anionic surfactants perform better on thewettability alteration of shale rocks than studied nonionic surfactants, and the key factor to enhance theshale oil recovery may be wettability alteration.

Proactive Frequency-Hopping Dynamic Spectrum Access Against Asynchronous Interchannel Spectrum Sensing

Junrong Gu,Wha Sook Jeon,Jae Moung Kim IEEE 2013 IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY Vol.62 No.8

<P>In the frequency-hopping-based dynamic spectrum access (FH-DSA) methods, both reactive and proactive channel switching (CS) schemes are widely adopted. However, when they are coupled with asynchronous interchannel spectrum sensing (moments), there are at least two drawbacks in these CS schemes, i.e., producing more interference to a primary user (PU) and fewer throughputs to a secondary user (SU). Therefore, to overcome these two drawbacks, we propose a proactive FH-DSA method against asynchronous interchannel spectrum sensing with reduced interference to the PU, while enhancing the SU throughput by eliminating the spectrum sensing time overhead during CS. The optimal FH policy is obtained by formulating proactive FH-DSA in the dynamic programming framework. Furthermore, we derive the theoretical average interference and the bound of average delay under the proposed FH-DSA. Based on them, while considering the tradeoff between exploration and exploitation, and the practical requirements for interference and throughput, we propose one extension which proactively takes FH subject to an interference constraint to further reduce interference. The complexity of the proposed schemes is also analyzed. Finally, simulation results show the performance improvement of the proposed schemes.</P>

Side Lobe Suppression Based on Optimized Phase Rotation Sequence

GU, Junrong,HWANG, Jae Ho,HAN, Ning,KIM, Jae Moung The Institute of Electronics, Information and Comm 2010 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.93 No.2

<P>This paper proposes an optimized phase rotation sequence method for side lobe suppression by complementing and regulating the side lobe suppression sequence set. The sequence set is efficiently enhanced through the quadratically constrained least square model. The theoretical suppression performance of our method is discussed. Furthermore, our scheme is also suitable for cognitive radio, which is analyzed in the simulation part. The simulation results confirm the effectiveness of our schemes.</P>

Spectrum Sensing by Exploiting the Similarity of PDFs of Two Time-Adjacent Detected Data Sets with Cross Entropy

GU, Junrong,LIU, Wenlong,JANG, Sung Jeen,KIM, Jae Moung 'Institute of Electronics, Information and Communi 2011 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.eb94 No.12

Alterations in antioxidant function and cell apoptosis in duck spleen exposed to molybdenum and/or cadmium

Mengmeng Zhang,Junrong Luo,Caiying Zhang,Huabin Cao,Bing Xia,Guoliang Hu 대한수의학회 2017 Journal of Veterinary Science Vol.18 No.2

To investigate the effects of molybdenum (Mo) and/or cadmium (Cd) on antioxidant function and the apoptosis-related genes in duck spleens. Sixty healthy 11-day-old ducks were randomly divided into six groups of 10 ducks (control, low Mo group, high Mo, Cd, low Mo + Cd, and high Mo + Cd groups). All were fed a basal diet containing low or high dietary doses of Mo and/or Cd. Relative spleen weight, antioxidant indices, apoptosis-related gene mRNA expression levels, and ultrastructural changes were evaluated after 120 days. The results showed that the relative spleen weight decreased significantly in the high Mo + Cd treatment group which compared with control group. Malondialdehyde levels increased and xanthine oxidase and catalase activities decreased in the Mo and/or Cd groups compared with levels in the control group. Bak-1 and Caspase-3 expressions were upregulated in the high Mo + Cd group, while Bcl-2 was downregulated. In addition, mitochondrial crest fracture, swelling, vacuolation, deformed nuclei, and karyopyknosis in both Mo + Cd treated groups were more severe than in the other groups. The results suggest that Mo and/or Cd can induce oxidative stress and apoptosis of spleen via effects on the mitochondrial intrinsic pathway. Moreover, the results indicate the two elements have a possible synergistic relationship.

Chaotic‐Maps‐Based Hash Function and Its Application

Yanzhang Pan,Minglu Jin,Junrong Gu 한국어정보학회 2007 한국어정보학 Vol.9 No.1

A new hash algorithm with private key is proposed based on chaotic‐mapping, by reshaping a piece‐wise linear chaotic mapping. This algorithm based on the cipher block chain mode makes the iteration initial point as the private key, encrypts arbitrary length plaintext data to 128 bits hash value. The proposed algorithm encrypts multi‐bit at one time, which reduces the chaotic iterating times and improves the encryption speed. Through theoretical analysis and simulation results, the proposed hash function could satisfy the requirements of unidirectionality, initial value and key sensitivity, anti‐collision and real time, which could be applied to the identity authentication conveniently, safely and efficiently.

Asynchronous Cooperative Spectrum Sensing Scheme on Primary Users with Fast “On/Off” State Variations in Spectrum Sensing Windows

Jingying Jin(김정영),Junrong Gu(구준룡),Jae Moung Kim(김재명) 한국통신학회 2013 韓國通信學會論文誌 Vol.25 No.8

Cognitive Radio has attracted intensive interests of the researchers, recently. The data rate always increases in the emerging technologies. The increased data rate poses mainly two challenges for spectrum sensing. One is that the state of primary user (PU) is fast and alternatively varying between “on/off” in a spectrum sensing window. The other is that the asynchronicity among the reports in a cooperative spectrum sensing setting becomes more apparent. Both of them would deteriorate the spectrum sensing performance. Thus, we propose an asynchronous cooperative spectrum sensing method to cope with these two challenges. A likelihood ratio test based spectrum sensing is developed for a single cooperator. The likelihood ratio is obtained in the setting of fast varying PU state. The likelihood ratio test is uniformly powerful according to the Neyman-pearson lemma. Furthermore, the asynchronicity among the cooperators are studied. Two sets of fusion weights are discussed for the asynchronous time among cooperators. One is designed based on the condition probability of the PU state variation and the other one is designed based on the queueing theory. The simulation results are provided with different fusion methods. The performance improvements are demonstrated.

An Improved DSA Strategy based on Triple-States Reward Function

타사미아(Tasmia Ahmed),구준롱(Junrong Gu),장성진(Sung Jeen Jang),김재명(Jae Moung Kim) 大韓電子工學會 2010 電子工學會論文誌-TC (Telecommunications) Vol.47 No.11

본 논문은 보상함수 수정을 통해 보다 완벽한 DSA(Dynamic Spectrum Access)를 수행하는 새로운 방법을 제시하였다. POMDP(Partially Observable Markov Decision Process)는 미래의 스펙트럼 상태를 예측하는데 사용되는 알고리즘으로서, 그 중 보상함수는 스펙트럼을 예측하는데 있어 가장 중요한 부분이다. 그러나 보상함수는 Busy 및 Idle의 두 가지 상태만 갖고 있기 때문에 채널에서 충돌이 발생하게 되면 보상함수는 Busy를 반환함으로써 2차 사용자의 성능을 감소시키게 된다. 따라서 본 논문에서는 기존의 Busy를 Busy 및 Collision 의 두 상태로 구분하였고, 이렇게 추가된 Collision 상태를 통해 2차 사용자의 채널 접근 기회를 보다 향상시킴으로서 데이터 전송율을 증대시킬 수 있도록 하였다. 또한 본 논문은 새로운 알고리즘의 신뢰도 벡터를 수학적으로 분석하였다. 마지막으로 시뮬레이션 결과를 통해 개선된 보상함수의 성능을 검증하고, 이를 통해 새로운 알고리즘이 CR 네트워크에서 2차 사용자의 성능을 향상시킬 수 있음을 보인다. In this paper, we present a new method to complete Dynamic Spectrum Access by modifying the reward function. Partially Observable Markov Decision Process (POMDP) is an eligible algorithm to predict the upcoming spectrum opportunity. In POMDP, Reward function is the last portion and very important for prediction. However, the Reward function has only two states (Busy and Idle). When collision happens in the channel, reward function indicates busy state which is responsible for the throughput decreasing of secondary user. In this paper, we focus the difference between busy and collision state. We have proposed a new algorithm for reward function that indicates an additional state of collision which brings better communication opportunity for secondary users. Secondary users properly utilize opportunities to access Primary User channels for efficient data transmission with the help of the new reward function. We have derived mathematical belief vector of the new algorithm as well. Simulation results have corroborated the superior performance of improved reward function. The new algorithm has increased the throughput for secondary user in cognitive radio network.