• 제목/요약/키워드: Optimal allocation scheme

검색결과 189건 처리시간 0.026초

Coalition based Optimization of Resource Allocation with Malicious User Detection in Cognitive Radio Networks

  • Huang, Xiaoge;Chen, Liping;Chen, Qianbin;Shen, Bin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제10권10호
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    • pp.4661-4680
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    • 2016
  • Cognitive radio (CR) technology is an effective solution to the spectrum scarcity issue. Collaborative spectrum sensing is known as a promising technique to improve the performance of spectrum sensing in cognitive radio networks (CRNs). However, collaborative spectrum sensing is vulnerable to spectrum data falsification (SSDF) attack, where malicious users (MUs) may send false sensing data to mislead other secondary users (SUs) to make an incorrect decision about primary user (PUs) activity, which is one of the key adversaries to the performance of CRNs. In this paper, we propose a coalition based malicious users detection (CMD) algorithm to detect the malicious user in CRNs. The proposed CMD algorithm can efficiently detect MUs base on the Geary'C theory and be modeled as a coalition formation game. Specifically, SSDF attack is one of the key issues to affect the resource allocation process. Focusing on the security issues, in this paper, we analyze the power allocation problem with MUs, and propose MUs detection based power allocation (MPA) algorithm. The MPA algorithm is divided into two steps: the MUs detection step and the optimal power allocation step. Firstly, in the MUs detection step, by the CMD algorithm we can obtain the MUs detection probability and the energy consumption of MUs detection. Secondly, in the optimal power allocation step, we use the Lagrange dual decomposition method to obtain the optimal transmission power of each SU and achieve the maximum utility of the whole CRN. Numerical simulation results show that the proposed CMD and MPA scheme can achieve a considerable performance improvement in MUs detection and power allocation.

Power Allocation for Opportunistic Full-Duplex based Relay Selection in Cooperative Systems

  • Zhong, Bin;Zhang, Dandan;Zhang, Zhongshan
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제9권10호
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    • pp.3908-3920
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    • 2015
  • In this paper, performance analysis of full-duplex (FD) relay selection under decode-and-forward (DF) relaying mode is carried out by taking into account several critical factors, including the distributions of the received signal-to-noise ratio (SNR) and the outage probability of wireless links. The tradeoff between the FD and half-duplex (HD) modes for relay selection techniques is also analyzed, where the former suffers from the impact of residual self-interference, but the latter requires more channel resources than the former (i.e., two orthogonal channels are required). Furthermore, the impact of optimal power allocation (OPA) on the proposed relay-selection scheme is analyzed. Particularly, the exact closed-form expressions for outage probability of the proposed scheme over Rayleigh fading channels are derived, followed by validating the proposed analysis using simulation. Numerical results show that the proposed FD based scheme outperforms the HD based scheme by more than 4 dB in terms of coding gain, provided that the residual self-interference level in the FD mode can be substantially suppressed to the level that is below the noise power.

QoS Constrained Optimization of Cell Association and Resource Allocation for Load Balancing in Downlink Heterogeneous Cellular Networks

  • Su, Gongchao;Chen, Bin;Lin, Xiaohui;Wang, Hui;Li, Lemin
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제9권5호
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    • pp.1569-1586
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    • 2015
  • This paper considers the optimal cell association and resource allocation for load balancing in a heterogeneous cellular network subject to user's quality-of-service (QoS) constraints. We adopt the proportional fairness (PF) utility maximization formulation which also accommodates the QoS constraints in terms of minimum rate requirements. With equal resource allocation this joint optimization problem is either infeasible or requires relaxation that yields a solution which is difficult to implement. Nevertheless, we show that this joint optimization problem can be effectively solved without any priori assumption on resource allocation and yields a cell association scheme which enforces single BS association for each user. We re-formulated the joint optimization problem as a network-wide resource allocation problem with cardinality constraints. A reweighted heuristic l1-norm regularization method is used to obtain a sparse solution to the re-formulated problem. The cell association scheme is then derived from the sparsity pattern of the solution, which guarantees a single BS association for each user. Compared with the previously proposed method based on equal resource allocation, the proposed framework results in a feasible cell association scheme and yields a robust solution on resource allocation that satisfies the QoS constraints. Our simulations illustrate the impact of user's minimum rate requirements on cell association and demonstrate that the proposed approach achieves load balancing and enforces single BS association for users.

KModSim 모형(模型)에 의한 도시지역(都市地域) 다중수원(多衆水源) 송수관망간(送水管網間) 최적(最適) 연계(連繫) 운영(運營) 연구(硏究) (An Optimal Conjunctive Operation of Water Transmission Systems from Multiple Sources with applying EPAnet and KModSim Model)

  • 류태상;정태성;고익환;하성룡
    • 한국수자원학회:학술대회논문집
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    • 한국수자원학회 2008년도 학술발표회 논문집
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    • pp.500-504
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    • 2008
  • The objective of this paper is to evaluate the feasibility of using an optimization model as a effective way to search conjunctive operation scheme to meet two conditions; one is to minimize the electric cost for pumping and another is to meet the water demand for satisfying customers. The feasibility is confirmed as comparing the best combinations of pumps between multi-regional water supply networks from multiple sources which are obtained through an optimization modeling and EPAnet modeling. KModsim model, a network optimization model, was used to determine conjunctive operation scheme in the pipe system. KModsim, based on Lagrangian Relaxation algorithm, is useful for modeling network system and obtaining simultaneously pump combination and water allocation with given input option such as energy unit cost supplying from a source into a consumer, operating pumping combination. This study develops the procedure of determining optimal conjunctive operation scheme with using KModsim model. As a study region, the water supplying systems of the Geojae-city in the Geongsang Namdo Province was selected and investigated. The EPAnet hydraulic simulation result(Ryu et al, 2007, KSWW) gave input data for optimization model; energy unit price(won/$m^3$), water service available area etc.. It was assured that the combination of pump operation through optimum conjunctive operation is to be optimum scheme to obtain the best economic water allocation with comparison to the hydraulic simulation result such as electric cost and pump combination cases. The results obtained through the study are as follows. First, It was found that a well-allocated water supply scheme, the best combination of pump operation through optimum joint operation, promises to save the electric cost and satisfy all operational goals such as stability and revenues during the period. Second, an application of KModSim, a network model, gave the amount of water allocation from each source to a consumer with consideration of economic supply. Finally, in a service area available to supply through conjunctive operation of existing inter-regional water supply networks within short distance, a conjunctive operation is useful for determining each transmission pipeline's service area and maximizing the effectiveness of optimizations in pumping operation time.

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OFDMA 시스템에서 이종 트래픽의 QoS를 보장하기 위한 자원 할당 기법 (Resource Allocation Scheme for Ensuring QoS of Heterogeneous Traffic in OFDMA System)

  • 곽용수;고정하;김영용
    • 한국통신학회논문지
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    • 제35권5A호
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    • pp.447-451
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    • 2010
  • 본 논문은 OFDMA 시스템에서 이종 트래픽의 QoS를 보장하기 위한 자원할당 기법을 제안하였다. OFDMA 시스템에서 NRT(non-real time), RT(real time), 멀티캐스트 패킷이 송신 단에 동시에 도달할 경우, 각트래픽이 요구하는 QoS를 각각 반영하는 OFDMA 자원할당 기법이 필요하다. 본 논문에서는 BMPA (balanced multimedia packet allocation)기법을 바탕으로, 채널용량이 가장 놓은 서브캐리어를 멀티캐스트 패킷을 전송하기 위한 멀티캐스트 채널로 설정하는 advanced BMPA 기법을 제안하였다. 본 기법은 RT 패킷과 멀티캐스트 패킷에 NRT 패킷보다 더 큰 가중치를 부여하여 각 사용자의 패킷 가중치 합에 따라서 서브 캐리어를 할당한다. 시뮬레이션 결과를 통해 advanced BMPA 기법이 기존의 멀티캐스트를 고려한 멀티유저 워터필링과 BMPA 기법에 비해 장기적으로 시스템의 전송 속도를 높이고 멀티미디어 패킷 지연을 줄인다는 사실을 증명했다.

Selection Based Cooperative Beamforming and Power Allocation for Relay Networks

  • Liu, Yi;Nie, Weiqing
    • Journal of Communications and Networks
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    • 제13권4호
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    • pp.377-384
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    • 2011
  • Cooperative beamforming has previously been proven to be an efficient way to improve the cooperative diversity. This method generally requires all relay nodes to participate in beamforming, which can be seen as "all participate" cooperative beamforming. However, not all relay nodes have constructive impacts on the end-to-end bit error rate (BER) performance. Based on this observation, we propose a new cooperative scheme which only selects those "appropriate" relay nodes to perform cooperative beamforming. Such relay nodes can be simply determined with mean channel gains. Therefore, the selection complexity is significantly reduced as global instantaneous channel state information is not required. This scheme guarantees that energy is only allocated to the "appropriate" relay nodes, and hence provides superior diversity. We also prove that power allocation among source and selected relay nodes is a convex problem, and can be resolved with lower computational complexity. Simulation results demonstrate that our scheme achieves an essential improvement in terms of BER performance for both optimal and limited feedback scenarios, as well as high energy-efficiency for the energy-constrained networks.

Power allocation-Assisted secrecy analysis for NOMA enabled cooperative network under multiple eavesdroppers

  • Nayak, V. Narasimha;Gurrala, Kiran Kumar
    • ETRI Journal
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    • 제43권4호
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    • pp.758-768
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    • 2021
  • In this work, the secrecy of a typical wireless cooperative dual-hop non-orthogonal multiple access (NOMA)-enabled decode-and-forward (DF) relay network is investigated with the impact of collaborative and non-collaborative eavesdropping. The system model consists of a source that broadcasts the multiplexed signal to two NOMA users via a DF relay, and information security against the eavesdropper nodes is provided by a helpful jammer. The performance metric is secrecy rate and ergodic secrecy capacity is approximated analytically. In addition, a differential evolution algorithm-based power allocation scheme is proposed to find the optimal power allocation factors for relay, jammer, and NOMA users by employing different jamming schemes. Furthermore, the secrecy rate analysis is validated at the NOMA users by adopting different jamming schemes such as without jamming (WJ) or conventional relaying, jamming (J), and with control jamming (CJ). Simulation results demonstrate the superiority of CJ over the J and WJ schemes. Finally, the proposed power allocation outperforms the fixed power allocation under all conditions considered in this work.

Joint Transmission Slot Assignment, FSO Links Allocation and Power Control for Hybrid RF/FSO Wireless Mesh Networks

  • Zhao, Yan;Shi, Wenxiao;Shi, Hanyang;Liu, Wei;Wu, Pengxia
    • Current Optics and Photonics
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    • 제1권4호
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    • pp.325-335
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    • 2017
  • Hybrid radio frequency/free space optical (RF/FSO) wireless mesh networks have attracted increasing attention for they can overcome the limitations of RF and FSO communications and significantly increase the throughput of wireless mesh networks (WMNs). In this article, a resource assignment optimization scheme is proposed for hybrid RF/FSO wireless mesh networks. The optimization framework is proposed for the objective of maximizing throughput of overall hybrid networks through joint transmission slot assignment, FSO links allocation and power control with the consideration of the fading nature of RF and FSO links. The scheme is formulated as an instance of mixed integer linear program (MILP) and the optimal solutions are provided using CPLEX and Gurobi optimizers. How to choose the appropriate optimizer is discussed by comparing their performance. Numerous simulations are done to demonstrate that the performance of our optimization scheme is much better than the current case of having the same topology.

사용자 릴레이를 채택한 협동 NOMA 시스템의 최적 전력할당 (Optimum Power Allocation of Cooperative NOMA Systems based on User Relay)

  • 김남수
    • 한국인터넷방송통신학회논문지
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    • 제17권5호
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    • pp.25-33
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    • 2017
  • NOMA (Non-orthogonal multiple access) 시스템은 스펙트럼 효율이 높기 때문에 제5세대 이동통신 방식에서 다중화 방식으로 채택이 매우 유력하다. 본 논문에서는 사용자를 릴레이로 채택한 협동 NOMA 시스템에서 오수신율을 최소화하기 위한 최적의 전력 할당 방법에 관하여 연구하였다. 먼저 릴레이 사용자 및 선택 결합을 갖는 목적지 사용자의 오수신율을 유도한 후, 이를 바탕으로 협동 NOMA 시스템의 오수신율을 유도하였다. 해석적으로 유도한 결과는 Monte Carlo 시뮬레이션한 결과로 입증하였다. 유도한 시스템의 오수신율은 Convex 함수가 되기 때문에, 오수신율을 최저로 하는 전력할당 값을 최적의 전력할당 계수로 구하였다. 수치적인 계산 결과 목적지 사용자가 요구하는 전송용량이 커질수록 최적의 전력할당 계수가 증가하는 것을 알 수 있었다. 그리고 목적지 사용자의 전송용량이 고정된 경우, 릴레이 사용자가 요구하는 전송용량이 증가할수록 최적의 전력 할당계수는 감소하였다.

Power Allocation Schemes For Downlink Cognitive Radio Networks With Opportunistic Sub-channel Access

  • Xu, Ding;Feng, Zhiyong;Zhang, Ping
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • 제6권7호
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    • pp.1777-1791
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    • 2012
  • This paper considers a downlink cognitive radio (CR) network where one secondary user (SU) and one primary user (PU) share the same base station (BS). The spectrum of interest is divided into a set of independent, orthogonal subchannels. The communication of the PU is of high priority and the quality of service (QoS) is guaranteed by the minimum rate constraint. On the other hand, the communication of the SU is of low priority and the SU opportunistically accesses the subchannels that were previously discarded by the PU during power allocation. The BS assigns fractions ?? and 1 ?? of the total available transmit power to the PU and the SU respectively. Two power allocation schemes with opportunistic subchannel access are proposed, in which the optimal values of ??'s are also obtained. The objective of one scheme is to maximize the rate of the SU, and the objective of the other scheme is to maximize the sum rate of the SU and the PU, both under the PU minimum rate constraint and the total transmit power constraint. Extensive simulation results are obtained to verify the effectiveness of the proposed schemes.