Cognitive radio is being widely discussed,and resource allocation scheme is drawing a lot of attention.Although the existed resource allocation strategies have successfully enhanced spectrum efficiency,some critical c...Cognitive radio is being widely discussed,and resource allocation scheme is drawing a lot of attention.Although the existed resource allocation strategies have successfully enhanced spectrum efficiency,some critical challenges still remain unanswered such as the jointly consideration of the efficiency and fairness,the rational description of the spectrum resources,and the execution mode of the spectrum allocation.This paper presents a system level dynamic frequency spectrum allocation scheme based on a central heterogeneous network architecture,evaluates the matching degree of the spectrum demand and the available spectrum resources with corresponding matrices,jointly considers the efficiency and fairness of different cognitive radio systems.Simulation results and the application scenario are also presented and analyzed.展开更多
Collaborative transmission among evolved Node-Bs(eNBs)is one of the promising techniques for LTE-Advanced to provide broader coverage and higher spectral efficiency.The interference among multi-cell transmission can b...Collaborative transmission among evolved Node-Bs(eNBs)is one of the promising techniques for LTE-Advanced to provide broader coverage and higher spectral efficiency.The interference among multi-cell transmission can be mitigated by joint precoding,such as multi-cell block diagonalization(BD)at cooperative eNBs.The major difference between multi-cell and single-cell transmission is that the power constraint has to be considered on a per-eNB basis.To satisfy per-eNB power constraint(PePC),a simplified power allocation algorithm for the multi-cell BD based collaborative transmission is proposed in this paper.The algorithm provides a power allocation coefficient matrix for BD to meet PePC.Simulation results demonstrate that the proposed algorithm has a near-optimal performance with simplicity.展开更多
This article studies the degree distribution property of low density parity check （LDPC） codes by Gaussian approximation （GA） and presents an efficient hybrid automatic repeat quest （HARQ） scheme for LDPC-coded ...This article studies the degree distribution property of low density parity check （LDPC） codes by Gaussian approximation （GA） and presents an efficient hybrid automatic repeat quest （HARQ） scheme for LDPC-coded orthogonal frequency division multiplexing （OFDM） system. In the scheme, the important bits with large degrees have high retransmission priorities and are mapped to the sub-carriers with better channel quality indicator （CQI） levels in the OFDM system. The new scheme provides more protection to the bits with large degrees and thus contributes more to the decoding process by offering more transmission power. In this way the system performance would be improved. The statistics and simulation results also prove the new scheme.展开更多
文摘Cognitive radio is being widely discussed,and resource allocation scheme is drawing a lot of attention.Although the existed resource allocation strategies have successfully enhanced spectrum efficiency,some critical challenges still remain unanswered such as the jointly consideration of the efficiency and fairness,the rational description of the spectrum resources,and the execution mode of the spectrum allocation.This paper presents a system level dynamic frequency spectrum allocation scheme based on a central heterogeneous network architecture,evaluates the matching degree of the spectrum demand and the available spectrum resources with corresponding matrices,jointly considers the efficiency and fairness of different cognitive radio systems.Simulation results and the application scenario are also presented and analyzed.
基金supported by the Research Institution of China Mobile.
文摘Collaborative transmission among evolved Node-Bs(eNBs)is one of the promising techniques for LTE-Advanced to provide broader coverage and higher spectral efficiency.The interference among multi-cell transmission can be mitigated by joint precoding,such as multi-cell block diagonalization(BD)at cooperative eNBs.The major difference between multi-cell and single-cell transmission is that the power constraint has to be considered on a per-eNB basis.To satisfy per-eNB power constraint(PePC),a simplified power allocation algorithm for the multi-cell BD based collaborative transmission is proposed in this paper.The algorithm provides a power allocation coefficient matrix for BD to meet PePC.Simulation results demonstrate that the proposed algorithm has a near-optimal performance with simplicity.
基金supported by the National Natural Science Foundation of China (60501007).
文摘This article studies the degree distribution property of low density parity check （LDPC） codes by Gaussian approximation （GA） and presents an efficient hybrid automatic repeat quest （HARQ） scheme for LDPC-coded orthogonal frequency division multiplexing （OFDM） system. In the scheme, the important bits with large degrees have high retransmission priorities and are mapped to the sub-carriers with better channel quality indicator （CQI） levels in the OFDM system. The new scheme provides more protection to the bits with large degrees and thus contributes more to the decoding process by offering more transmission power. In this way the system performance would be improved. The statistics and simulation results also prove the new scheme.
