To enhance the bandwidth efficiency of the guard interval （GI） assisted wireless communication system, an attractive scheme is proposed, which combines the functions of pilots and the GI together, so that the pilot ...To enhance the bandwidth efficiency of the guard interval （GI） assisted wireless communication system, an attractive scheme is proposed, which combines the functions of pilots and the GI together, so that the pilot resource used for estimating channel state is saved. Based on the proposed different known guard intervals （DKGI）, the time-domain channel estimation can be simply applied on the receiver side. After channel estimation, the receiver can employ the cyclic convolution restoring （CCR） function to reconstruct the cyclical convolution relationship between the signal and the channel, by which the receiver can also achieve good performance through the conventional 1-tap frequency domain equalization （FDE）.展开更多
Up to now, how to construct an efficient secure group signature scheme, which needs not to reset the system when some group members' signing keys are exposed, is still a difficult problem. A construction concernin...Up to now, how to construct an efficient secure group signature scheme, which needs not to reset the system when some group members' signing keys are exposed, is still a difficult problem. A construction concerning revocation of group members is an ideal one if it satisfies forward security which makes it more attractive for not sacrificing the security of past signatures of deleted members. This paper analyses the problem and gives a construction in which the group manager can be un-trustworthy. The scheme is efficient even when the number of revoked members is large.展开更多
基金The National High Technology Research and Deve-lopment Program of China (863Program)(No.2002AA123031).
文摘To enhance the bandwidth efficiency of the guard interval （GI） assisted wireless communication system, an attractive scheme is proposed, which combines the functions of pilots and the GI together, so that the pilot resource used for estimating channel state is saved. Based on the proposed different known guard intervals （DKGI）, the time-domain channel estimation can be simply applied on the receiver side. After channel estimation, the receiver can employ the cyclic convolution restoring （CCR） function to reconstruct the cyclical convolution relationship between the signal and the channel, by which the receiver can also achieve good performance through the conventional 1-tap frequency domain equalization （FDE）.
基金the National Natural Science Foundation of China (No.60673081)the National Grand Foundation Research 863 Program of China (No.2006 AA01Z417).
文摘Up to now, how to construct an efficient secure group signature scheme, which needs not to reset the system when some group members' signing keys are exposed, is still a difficult problem. A construction concerning revocation of group members is an ideal one if it satisfies forward security which makes it more attractive for not sacrificing the security of past signatures of deleted members. This paper analyses the problem and gives a construction in which the group manager can be un-trustworthy. The scheme is efficient even when the number of revoked members is large.
