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New family of hopping sequences for time/frequency-hopping CDMA systems
Fan, Pingzhi,Lee, Moon Ho,Peng, Daiyuan IEEE 2005 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.4 No.6
In this paper, a new family of hopping sequences with very large family size suitable for use in time/frequency-hopping (TH/FH) code-division multiple-access (CDMA) systems is proposed and investigated. The construction of the new hopping sequences is based upon the polynomial theory over the finite field, and the new hopping sequences are called the polynomial hopping sequences. It is shown that the new time/frequency-hopping sequences include the well-known cubic hopping sequences, quadratic hopping sequences, and linear hopping sequences as special cases, and are good candidates for the large-capacity ultrawide-bandwidth (UWB) radio systems.
( Kai Yu ),( Yi Sun ),( Pingzhi Fan ),( Xianfu Lei ),( Lei Shu ) 한국인터넷정보학회 2010 KSII Transactions on Internet and Information Syst Vol.4 No.4
The random access systems, with retransmission diversity (RD) employment, over large random spreading code division multiple access (CDMA) channel subject to fading is investigated, under the assumption of infinite number of users and infinite spreading gain with their ratio converging to a constant. The low bound of the signal to interference and noise ratio (SINR) is shown to converge almost surely to a constant. The throughput, spectrum efficiency and energy efficiency in the dominating systems are obtained. The analytical results are confirmed by simulations. We find that in high traffic loads the throughput with fading is higher than that without. When the energy efficiency increases, the spectrum efficiency tends to two contrary values due to SNR increases or decreases. For the ordinary stable systems, the stability region is shown to shrink as the traffic increases and enlarge with RD employment.
( Shi-jinn Horng ),( Shiang-feng Tzeng ),( Pingzhi Fan ),( Xian Wang ),( Tianrui Li ),( Muhammad Khurram Khan ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.6
A convertible undeniable signature requires a verifier to interact with the signer to verify a signature and furthermore allows the signer to convert a valid one to publicly verifiable signature. In 2007, Yuen et al. proposed a convertible undeniable signature without random oracles in pairings. However, it is recently shown that Yuen et al.`s scheme is not invisible for the standard definition of invisibility. In this paper, we propose a new improvement by using extended Euclidean algorithm that can overcome the visibility attack. The proposed scheme has been evaluated based on computation and communication complexities and the performance comparisons of Yuen et al.`s scheme and various convertible undeniable signature schemes are provided. Moreover, it has been observed that the proposed algorithm reduces the computation and communication times significantly.
Power-Space Functions in High Speed Railway Wireless Communications
Yunquan Dong,Chenshuang Zhang,Pingyi Fan,Pingzhi Fan 한국통신학회 2015 Journal of communications and networks Vol.17 No.3
To facilitate the base station planning in high speed railway communication systems, it is necessary to consider the functional relationships between the base station transmit power and space parameters such as train velocity and cell radius. Since these functions are able to present some inherent system properties determined by its spatial topology, they will be referred to as the power-space functions in this paper. In light of the fact that the line-of-sight path persists the most power of the received signal of each passing train, this paper considers the average transmission rate and bounds on power-space functions based on the additive white Gaussian noise channel (AWGN) model. As shown by Monte Carlo simulations, using AWGN channel instead of Rician channel introduces very small approximation errors, but a tractable mathematical framework and insightful results. Particularly, lower bounds and upper bounds on the average transmission rate, as well as transmit power as functions of train velocity and cell radius are presented in this paper. It is also proved that to maintain a fixed amount of service or a fixed average transmission rate, the transmit power of a base station needs to be increased exponentially, if the train velocity or cell radius is increased, respectively.