The asymptotical Gaussianity of the capacity-achieving distribution is also shown. Based on the derived lower bound, the inherent capacity loss of a noncoherent channel, as compared to a coherent one, may be considered very limited for all but very small values of N . This result may be viewed as the information theoretic counterpart of a similar conclusion derived by many authors with reference to the probability of detection error. 1 are compared in the presence of narrow band and wide band interferers, over AWGN and non linear channels. The purpose of this work is to help finding out the most suitable modulation scheme for the increasingly crowded frequency bands available for space research missions.
Mobile computing is a newly emerging computing paradigm.
Whether using the term mobile database system or some other form, the database concept is essential to the mobile computing environment. This work employs a more thorough yet general means of defining the mobile database system, along with several application scenarios. Possible secure access schemes are also presented for databases in a mobile computing environment. The tradeoffs of these schemes are also analyzed. Moreover, the feasibility of applying some possible secure access methods is explored, along with the potential difficulties and unresolved issues.