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Yuanyuan Yao,Chang-chuan Yin,Xiaoshi Song,Norman C. Beaulieu 한국통신학회 2016 Journal of communications and networks Vol.18 No.3
The performance of large-scale cognitive radio (CR) networkswith secondary users sustained by opportunistically harvestingradio-frequency (RF) energy from nearby primary transmissionsis investigated. Using an advanced RF energy harvester, asecondary user is assumed to be able to collect ambient primary RFenergy as long as it lies inside the harvesting zone of an active primarytransmitter (PT). A variable power (VP) transmission modeis proposed, and an energy-based opportunistic spectrum access(OSA) strategy is considered, under which a secondary transmitter(ST) is allowed to transmit only if its harvested energy is largerthan a predefined transmission threshold and it is outside the guardzones of all active PTs. The transmission probability of the STs isderived. The outage probabilities and the throughputs of the primaryand the secondary networks, respectively, are characterized. Compared with prior work, the throughput can be increased byas much as 29%. The energy-based OSA strategy can be generallyapplied to a non-CR setup, where distributed power beacons(PBs) are deployed to power coexisting wireless signal transmitters(WSTs) in a wireless powered sensor network.
Block-Level Resource Allocation with Limited Feedback in Multicell Cellular Networks
Jian Yu,Chang-chuan Yin 한국통신학회 2016 Journal of communications and networks Vol.18 No.3
In this paper, we investigate the scheduling and powerallocation for coordinated multi-point transmission in downlinklong term evolution advanced (LTE-A) systems, where orthogonalfrequency division multiple-access is used. The proposed schemejointly optimizes user selection, power allocation, and modulationand coding scheme (MCS) selection to maximize the weighted sumthroughput with fairness consideration. Considering practical constraintsin LTE-A systems, the MCSs for the resource blocks assignedto the same user need to be the same. Since the optimizationproblemis a combinatorial and non-convex one with high complexity,a low-complexity algorithm is proposed by separating the userselection and power allocation into two subproblems. To furthersimplify the optimization problem for power allocation, the instantaneoussignal-to-interference-plus-noise ratio (SINR) and the averageSINR are adopted to allocate power in a single cell and multiplecoordinated cells, respectively. Simulation results show thatthe proposed scheme can improve the average system throughputand the cell-edge user throughput significantly compared with theexisting schemes with limited feedback.
A Novel Dynamic Spectrum Access Algorithm for Cognitive Radio Networks
Zhao, Ming,Yin, Chang-Chuan,Wang, Xiao-Jun The Korea Institute of Information and Commucation 2013 Journal of communications and networks Vol.15 No.1
This paper proposes a new dynamic spectrum access (DSA) algorithm for cognitive radio networks. Once initialized, this algorithm works without the need of coordination overhead and hence can be used when no control channel is available. Secondary user (SU) lists and predetermined access control are used in this algorithm. We analyze the probability of no SU collision with primary user and the throughput of our proposed algorithm. Extensive simulations show that our algorithm outperforms the existing DSA algorithm in terms of both the aggregate throughput and the traffic distribution fairness. Furthermore, the validity of our analysis is confirmed by simulation results.
Cao,Jain Min,Wu,Chuan Liang,Shen,Wen ZhEng,Huang,Chang,Li,Yin Bo,Xu,Yang Zhen 대한전자공학회 1997 ICVC : International Conference on VLSI and CAD Vol.5 No.1
Start with 2D simulation of hot-carrier injection current. in this pier, we have discussed the influence of different silicon film thickness (Tsi), gate oxide thickness (Tox1) and substrate doping (Na) an the hot-carrier effects of thin-film deep submicron SOI/MOSFET. Simulation results indicate that, with reduction of Tsi, the hot-carrier current is reduced (by more than 2 orders); and in Tsi range of 0.05-0.1μ. the hot carrier carrent is smallest and insensitive to Tox1, Na and Tsi. These are helpful to the design of high reliability SOI/MOSFET.
Nahida Kiran,Chunyu Pan,Sihua Wang,Chang-chuan Yin 한국통신학회 2020 Journal of communications and networks Vol.22 No.1
The rapid growth of the internet usage and the distributedcomputing resources of edge devices create a necessity tohave a reasonable controller to ensure efficient utilization of distributedcomputing resources in mobile edge computing (MEC). We envision the future MEC services, where quality of experience(QoE) of the services is further enhanced by software definednetworks (SDNs) capabilities to reduce the application-levelresponse time without service disruptions. SDN, which is not proposedspecifically for edge computing, can in fact serve as an enablerto lower the complexity barriers involved and let the realpotential of edge computing be achieved. In this paper, we investigatethe task offloading and resource allocation problem in wirelessMEC aiming to minimize the delay while saving the battery powerof user device simultaneously. However, it is challenging to obtainan optimal policy in such a dynamic task offloading system. Learningfrom experience plays a vital role in time variant dynamic systemswhere reinforcement learning (RL) takes a long term goal intoconsideration besides immediate reward, which is very importantfor a dynamic environment. A novel software defined edge cloudlet(SDEC) based RL optimization framework is proposed to tacklethe task offloading and resource allocation in wireless MEC. Specifically,Q-learning and cooperative Q-learning based reinforcementlearning schemes are proposed for the intractable problem. Simulationresults show that the proposed scheme achieves 31.39% and62.10% reduction on the sum delay compared to other benchmarkmethods such as traditional Q-learning with a random algorithmand Q-learning with epsilon greedy.