It is extensively approved that Channel State Information(CSI) plays an important role for synergetic transmission and interference management. However, pilot overhead to obtain CSI with enough precision is a signific...It is extensively approved that Channel State Information(CSI) plays an important role for synergetic transmission and interference management. However, pilot overhead to obtain CSI with enough precision is a significant issue for wireless communication networks with massive antennas and ultra-dense cell. This paper proposes a learning- based channel model, which can estimate, refine, and manage CSI for a synergetic transmission system. It decomposes the channel impulse response into multiple paths, and uses a learning-based algorithm to estimate paths' parameters without notable degradation caused by sparse pilots. Both indoor measurement and outdoor measurement are conducted to verify the feasibility of the proposed channel model preliminarily.展开更多
Mobility management is an important aspect of the LEO systems. In terrestrial wireless network, the movement of the user triggers the location updating and determines the paging scheme, while in LEO satellite systems,...Mobility management is an important aspect of the LEO systems. In terrestrial wireless network, the movement of the user triggers the location updating and determines the paging scheme, while in LEO satellite systems, the location updating and paging is mainly based on the movement of satellite. Terrestrial location management techniques must be altered to fit LEO systems. This paper introduces a modified movement based location update and paging scheme in LEO networks. In this scheme we propose the meta cell concept, which includes two spot beams of one satellite. First we present the location management scheme based on the architecture with meta cell location area. Then an analytical model is applied to formulate the cost of location updating and location paging for the and movement meta cell based dynamic location update scheme. The comparison of performance between meta cell architecture method and conventional signal spot cell architecture method is provided to demonstrate the cost effectiveness and robust of the proposed scheme under various parameters. To reduce the impact of meta cell architecture on location paging cost, we present forced location update strategy which used in the cases that the meta cell includes the two spot beams from different satellites.展开更多
Channel estimation is a key technology in indoor wireless visible light communications(VLCs).Using the training sequence(TS),this paper investigates the channel estimation in indoor wireless visible light communicatio...Channel estimation is a key technology in indoor wireless visible light communications(VLCs).Using the training sequence(TS),this paper investigates the channel estimation in indoor wireless visible light communications.Based on the propagation and signal modulation characteristics of visible light,a link model for the indoor wireless visible light communications is established.Using the model,three channel estimation methods,i.e.,the correlation method,the least square(LS) method and the minimum mean square error(MMSE) method,are proposed.Moreover,the performances of the proposed three methods are evaluated by computer simulation.The results show that the performance of the correlation method is the worst,the LS method is suitable for higher signal to noise ratio(SNR),and the MMSE method obtains the best performance at the expense of highest complexity.展开更多
基金supported by National Basic Research Program of China (NO 2012CB316002)China’s 863 Project (NO 2014AA01A703)+2 种基金National Major Projec (NO. 2014ZX03003002-002)Program for New Century Excellent Talents in University (NCET-13-0321)Tsinghua University Initiative Scientific Research Program (2011THZ02-2)
文摘It is extensively approved that Channel State Information(CSI) plays an important role for synergetic transmission and interference management. However, pilot overhead to obtain CSI with enough precision is a significant issue for wireless communication networks with massive antennas and ultra-dense cell. This paper proposes a learning- based channel model, which can estimate, refine, and manage CSI for a synergetic transmission system. It decomposes the channel impulse response into multiple paths, and uses a learning-based algorithm to estimate paths' parameters without notable degradation caused by sparse pilots. Both indoor measurement and outdoor measurement are conducted to verify the feasibility of the proposed channel model preliminarily.
文摘Mobility management is an important aspect of the LEO systems. In terrestrial wireless network, the movement of the user triggers the location updating and determines the paging scheme, while in LEO satellite systems, the location updating and paging is mainly based on the movement of satellite. Terrestrial location management techniques must be altered to fit LEO systems. This paper introduces a modified movement based location update and paging scheme in LEO networks. In this scheme we propose the meta cell concept, which includes two spot beams of one satellite. First we present the location management scheme based on the architecture with meta cell location area. Then an analytical model is applied to formulate the cost of location updating and location paging for the and movement meta cell based dynamic location update scheme. The comparison of performance between meta cell architecture method and conventional signal spot cell architecture method is provided to demonstrate the cost effectiveness and robust of the proposed scheme under various parameters. To reduce the impact of meta cell architecture on location paging cost, we present forced location update strategy which used in the cases that the meta cell includes the two spot beams from different satellites.
基金supported by the National Natural Science Foundation of China(No.60972023)the National Science and Technology Important Special Project(Nos.2010ZX03003-002 and 2010ZX03003-004)+4 种基金the Open Research Fund of National Mobile Communication Research Laboratory,Southeast University(No.2010D01)the Open Research Fund of State Key Laboratory of Advanced Optical Communication Systems and Networks,China(No.2008SH06)the Startup Fund of Nanjing University of Aeronautics and Astronautics(NUAA)the NUAA Research Funding(No.NS2010091)the Fundation of Graduate Innovation Center in NUAA
文摘Channel estimation is a key technology in indoor wireless visible light communications(VLCs).Using the training sequence(TS),this paper investigates the channel estimation in indoor wireless visible light communications.Based on the propagation and signal modulation characteristics of visible light,a link model for the indoor wireless visible light communications is established.Using the model,three channel estimation methods,i.e.,the correlation method,the least square(LS) method and the minimum mean square error(MMSE) method,are proposed.Moreover,the performances of the proposed three methods are evaluated by computer simulation.The results show that the performance of the correlation method is the worst,the LS method is suitable for higher signal to noise ratio(SNR),and the MMSE method obtains the best performance at the expense of highest complexity.
