Hirosuke Yamamoto

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This paper considers polar coding for asymmetric settings, that is, channel coding for asymmetric channels and lossy source coding for nonuniform sources and/or asymmetric distortion measures. The difficulty for asymmetric settings comes from the fact that the optimal symbol distributions of codewords are not always uniform. It is known that such nonuniform(More)
Rate-distortion theory is considered for the Shannon cipher system (SCS). The admissible region of cryptogram rateR, key rate Rk, legitimate receiver’s distortion D, and wiretapper’s uncertainty h is determined for the SCS with a noisy channel. Furthermore, inner and outer bounds of the admissible region of R, Rk, D, and wiretapper’s attainable minimum(More)
In a network with capacity h for multicast, information Xh = (X1, X2, · · · , Xh) can be transmitted from a source node to sink nodes without error by a linear network code. Furthermore, secret information S r = (S 1, S 2, · · · , S r) can be transmitted securely against wiretappers by k-secure network coding for k ≤ h−r. In this case, no information of the(More)
Using the Viterbi decoding algorithm with repeat request for convolutional codes is proposed, and the resuking performance is analyzed by random coding aud generatiug function arguments and by simtdation. It is &own that the reliability function of tbe proposed decoding algorithm is asymptotically twice that of the Viterbi decoding algorithm without repeat(More)
This correspondence is concerned with asymptotic properties on the codeword length of a fixed-to-variable length code (FV code) for a general source {X/sup n/}/sub n=1//sup /spl infin// with a finite or countably infinite alphabet. Suppose that for each n /spl ges/ 1 X/sup n/ is encoded to a binary codeword /spl phi//sub n/(X/sup n/) of length l(/spl(More)
Private information retrieval scheme for coded data storage is considered in this paper. We focus on the case where the size of each data record is large and hence only the download cost (but not the upload cost for transmitting retrieval queries) is of interest. We prove that the tradeoff between storage cost and retrieval/download cost depends on the(More)
Tomohiro Ogawa,* Akira Sasaki, Mitsugu Iwamoto, and Hirosuke Yamamoto Graduate School of Information Science and Technology, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656 Japan Sumitomo Mitsui Banking Corporation, 1–3–2, Marunouchi, Chiyoda-ku, Tokyo 100-0005 Japan Graduate School of Information Systems, University of Electro-Communications,(More)