In this paper, we propose an energy efficient user association scheme for uplink heterogeneous networks with machine-to-machine(M2M) and human-to-human(H2H) coexistence. A group based random access protocol is designe...In this paper, we propose an energy efficient user association scheme for uplink heterogeneous networks with machine-to-machine(M2M) and human-to-human(H2H) coexistence. A group based random access protocol is designed for massive number of machine-typecommunications(MTC) user equipments'(UEs) transmissions. A user association problem for UEs' energy efficiency maximization is formulated considering the HTC UEs' quality of service(QoS) guarantees and load balance among multiple BSs, simultaneously. A distributed iterative algorithm is developed to solve the optimization problem. In addition, the convergence of the proposed algorithm is proved. Simulation results show that our proposed scheme outperforms other schemes in terms of energy efficiency and QoS guarantees.展开更多
Cognitive Radio(CR) is a promising technology to solve the challenging spectrum scarcity problem.However, to implement CR, spectrum sensing is the groundwork and the precondition.In this paper, a collaborative spectru...Cognitive Radio(CR) is a promising technology to solve the challenging spectrum scarcity problem.However, to implement CR, spectrum sensing is the groundwork and the precondition.In this paper, a collaborative spectrum sensing scheme using fuzzy comprehensive evaluation is proposed.The final sensing decision of the proposed scheme is based on the combination of distributed sensing results of different Secondary Users(SUs).To improve the reliability of the sensing decision, the combination procedure takes into account the credibility of each SU, which is evaluated using fuzzy comprehensive evaluation.The effect of the presence of malicious SUs and malfunctioning SUs on the performance of the proposed scheme is also investigated.The efficiency of the scheme is validated through analysis and simulation.展开更多
This paper proposed a cross-layer dual adaptive coded modulation architecture using turbo codes for mobile muhimedia communication, which simultaneously adapted to both the varying channel characteristics and the qual...This paper proposed a cross-layer dual adaptive coded modulation architecture using turbo codes for mobile muhimedia communication, which simultaneously adapted to both the varying channel characteristics and the quality of service （QoS） of various mobile multimedia services to increase the average system throughput substantially. A pragmatic channel-adaptive turbo coded modulation scheme, which comes within 2.5dB of the Shannon limit, was optimally designed, and then a QoS-adaptive scheme was superimposed to build the dual adaptive architecture. Simulation results show that the novel dual adaption reduces the difference with the fading channel capacity to 2dB when assuming different services occur in equal probability and the service duration follows the exponential distribution.展开更多
A reduced-complexity detection algorithm is proposed, which is applied to iterative receivers for multiple-input multiple-output （MIMO） systems. Unlike the exhaustive search over all the possible trans-mitted symbol...A reduced-complexity detection algorithm is proposed, which is applied to iterative receivers for multiple-input multiple-output （MIMO） systems. Unlike the exhaustive search over all the possible trans-mitted symbol vectors of the optimum maximum a posteriori probability （MAP） detector, the new algo-rithm evaluates only the symbol vectors that contribute significantly to the soft output of the detector. The algorithm is facilitated by carrying out the breadth-first search on a reconfigurable tree, constructed by computing the symbol reliability of each layer based on zero-forcing criterion and reordering the symbols according to the symbol reliabilities. Simulations are presented and the good performance of the new algo-rithm over a quasi-static Rayleigh channel even for relatively small list sizes are proved.展开更多
HAPs(High-Altitude Platforms)are one of the most promising alternative infrastructures for providing wireless communications to overcome the shortcomings of terrestrial-tower-based and satellite systems.This paper inv...HAPs(High-Altitude Platforms)are one of the most promising alternative infrastructures for providing wireless communications to overcome the shortcomings of terrestrial-tower-based and satellite systems.This paper investigates a multipair two-way MM-AF(Massive MIMO Amplify-and-Forward)relay system over HAPs,where multiple user pairs exchange information within a pair through a relay with a very large number of antennas,and a HAP channel is modeled to follow a Rician fading distribution because of the presence of a line-of-sight path.First,the effect of hardware impairments on a multipair two-way MM-AF system is taken into consideration and is modeled using transmit and receive distortion noises.Then,ZFR/ZFT(Zero-Forcing Reception/Zero-Forcing Transmission)processing matrices of HDR(Half-Duplex Relaying)and FDR(Full-Duplex Relaying)with imperfect channel state information are presented.Finally,the asymptotic expressions of an end-to-end SINR are derived.Theoretical analyses and simulation results show that when the number of relay antennas grows very large,the SE(Spectral Efficiency)of an MM-AF relay system is limited by hardware impairments at the users instead of those at the relay,or by other types of interference.Thus,the quality of the hardware at a relay can be decreased without significantly degrading performance.展开更多
A satellite network system comprises three layers of satellites:LEO(Low Earth Orbit),MEO(Middle Earth Orbit)and GEO(Geostationary Orbit).In the system,users can choose a layer according to their demands,including QoS(...A satellite network system comprises three layers of satellites:LEO(Low Earth Orbit),MEO(Middle Earth Orbit)and GEO(Geostationary Orbit).In the system,users can choose a layer according to their demands,including QoS(Quality of Service),congestion,energy cost,etc.The utility that users gain will change when they access satellites in different layers.The mobility of satellites in the LEO and MEO leads to frequent handover among satellites in the same layer.These characteristics of multi-layered satellite networks make it possible for us to exploit the optimal distribution of users,which will maximize the utility of the entire satellite network.While the proposed problem is an NP-hard problem,we analyze the system based on the Markov chain and use the Markov approximation to approach the maximum utility.In addition,we use the count down and select algorithm to implement the process of Markov chain.The simulation results validate the convergence of the Markov approximation.In addition,the gap between the approximate value and optimal values decreases with an increase inβ,which is a positive constant in Markov formulation,according to the simulation results.展开更多
基金supported by Major Research Plan of National Natural Science Foundation of China(No.91438115)National Natural Science Foundation of China(No.61371123,No.61301165)+2 种基金Jiangsu Province Natural Science Foundation(BK2012055)China Postdoctoral Science Foundation(2014M552612)Jiangsu Postdoctoral Science Foundation(No.1401178C)
文摘In this paper, we propose an energy efficient user association scheme for uplink heterogeneous networks with machine-to-machine(M2M) and human-to-human(H2H) coexistence. A group based random access protocol is designed for massive number of machine-typecommunications(MTC) user equipments'(UEs) transmissions. A user association problem for UEs' energy efficiency maximization is formulated considering the HTC UEs' quality of service(QoS) guarantees and load balance among multiple BSs, simultaneously. A distributed iterative algorithm is developed to solve the optimization problem. In addition, the convergence of the proposed algorithm is proved. Simulation results show that our proposed scheme outperforms other schemes in terms of energy efficiency and QoS guarantees.
基金Supported by the National Natural Science Foundation of China (No.60672079)the Natural Science Foundation of Jiangsu Province (No.BK2006701 and No. BK2007002)
文摘Cognitive Radio(CR) is a promising technology to solve the challenging spectrum scarcity problem.However, to implement CR, spectrum sensing is the groundwork and the precondition.In this paper, a collaborative spectrum sensing scheme using fuzzy comprehensive evaluation is proposed.The final sensing decision of the proposed scheme is based on the combination of distributed sensing results of different Secondary Users(SUs).To improve the reliability of the sensing decision, the combination procedure takes into account the credibility of each SU, which is evaluated using fuzzy comprehensive evaluation.The effect of the presence of malicious SUs and malfunctioning SUs on the performance of the proposed scheme is also investigated.The efficiency of the scheme is validated through analysis and simulation.
基金Supported by the National High Technology Research and Development Programme of China (No. 2001AA121031 )the National Natural Science Foundation of China (No. 60072028)
文摘This paper proposed a cross-layer dual adaptive coded modulation architecture using turbo codes for mobile muhimedia communication, which simultaneously adapted to both the varying channel characteristics and the quality of service （QoS） of various mobile multimedia services to increase the average system throughput substantially. A pragmatic channel-adaptive turbo coded modulation scheme, which comes within 2.5dB of the Shannon limit, was optimally designed, and then a QoS-adaptive scheme was superimposed to build the dual adaptive architecture. Simulation results show that the novel dual adaption reduces the difference with the fading channel capacity to 2dB when assuming different services occur in equal probability and the service duration follows the exponential distribution.
基金Supported by the National Natural Science Foundation of China （No.60332030, 60572157） and the High Technology Research and Development Pro-gramme of China （No.2003AA123310）.
文摘A reduced-complexity detection algorithm is proposed, which is applied to iterative receivers for multiple-input multiple-output （MIMO） systems. Unlike the exhaustive search over all the possible trans-mitted symbol vectors of the optimum maximum a posteriori probability （MAP） detector, the new algo-rithm evaluates only the symbol vectors that contribute significantly to the soft output of the detector. The algorithm is facilitated by carrying out the breadth-first search on a reconfigurable tree, constructed by computing the symbol reliability of each layer based on zero-forcing criterion and reordering the symbols according to the symbol reliabilities. Simulations are presented and the good performance of the new algo-rithm over a quasi-static Rayleigh channel even for relatively small list sizes are proved.
基金supported by the Major Research Plan of the National Natural Science Foundation of China(No.91438115)the National Natural Science Foundation of China(Nos.61371123,61301165,61671472)+4 种基金Jiangsu Province Natural Science Foundation(No.BK20160079)Special Financial Grant of The China Postdoctoral Science Foundation(No.2015T81079)China Postdoctoral Science Foundation(No.2014M552612)Jiangsu Postdoctoral Science Foundation(No.1401178C)the Preresearch Project Foundation(No.9140C020306130C02007).
文摘HAPs(High-Altitude Platforms)are one of the most promising alternative infrastructures for providing wireless communications to overcome the shortcomings of terrestrial-tower-based and satellite systems.This paper investigates a multipair two-way MM-AF(Massive MIMO Amplify-and-Forward)relay system over HAPs,where multiple user pairs exchange information within a pair through a relay with a very large number of antennas,and a HAP channel is modeled to follow a Rician fading distribution because of the presence of a line-of-sight path.First,the effect of hardware impairments on a multipair two-way MM-AF system is taken into consideration and is modeled using transmit and receive distortion noises.Then,ZFR/ZFT(Zero-Forcing Reception/Zero-Forcing Transmission)processing matrices of HDR(Half-Duplex Relaying)and FDR(Full-Duplex Relaying)with imperfect channel state information are presented.Finally,the asymptotic expressions of an end-to-end SINR are derived.Theoretical analyses and simulation results show that when the number of relay antennas grows very large,the SE(Spectral Efficiency)of an MM-AF relay system is limited by hardware impairments at the users instead of those at the relay,or by other types of interference.Thus,the quality of the hardware at a relay can be decreased without significantly degrading performance.
基金supported by the National Natural Science Foundation of China(Nos.61325012,61428205,91438115,61532012,61671478,61672342).
文摘A satellite network system comprises three layers of satellites:LEO(Low Earth Orbit),MEO(Middle Earth Orbit)and GEO(Geostationary Orbit).In the system,users can choose a layer according to their demands,including QoS(Quality of Service),congestion,energy cost,etc.The utility that users gain will change when they access satellites in different layers.The mobility of satellites in the LEO and MEO leads to frequent handover among satellites in the same layer.These characteristics of multi-layered satellite networks make it possible for us to exploit the optimal distribution of users,which will maximize the utility of the entire satellite network.While the proposed problem is an NP-hard problem,we analyze the system based on the Markov chain and use the Markov approximation to approach the maximum utility.In addition,we use the count down and select algorithm to implement the process of Markov chain.The simulation results validate the convergence of the Markov approximation.In addition,the gap between the approximate value and optimal values decreases with an increase inβ,which is a positive constant in Markov formulation,according to the simulation results.
