Budget Amount *help 
¥2,900,000 (Direct Cost : ¥2,900,000)
Fiscal Year 1998 : ¥1,400,000 (Direct Cost : ¥1,400,000)
Fiscal Year 1997 : ¥1,500,000 (Direct Cost : ¥1,500,000)

Research Abstract 
This research treats a source coding problem for a multiterminal communication system with a twoway channel, which is an extended system of the wellknown SlepianWolf system. In the SlepianWolf system, correlated source outputs X and Y are encoded by two separate encoders, fx and fy, independently, and decoder g reproduces X and Y within an arbitrarily small error probability. The extended system consists of two encoders fx and fy, which encode X and Y, respectively, in the same way as the SlepianWolf system, and two decoders gx and gy. The encoders and decoders are connected by channels as fx*gx, fi*gy, gx <tautomer> gy. Two decoders are connected by a twoway channel, and they communicate each other before gx and gy reproduce X and Y respectively. The source coding problem is to determine the achievable rate region such that arbitrarily small decoding error probability can be attained if and only if the four rates of three channels are included in the achievable rate region. The main results of this research is the following. (1) It is shown that the achievable region of the treated system cannot be derived from the known results for various multiterminal systems, and it is clarified why the coding problem becomes difficult if a twoway channel is included in the communication system. (2) Outer and inner rate regions for the achievable region are derived theoretically. (3) The following problems have also been studied in the scope of source coding although they are not directly related to the above problem. (a) Analysis on the redundancy for universal codes with distortion, (b) Hit tree weighting method for gray scaled images, (c) Theoretical analysis on block sort data compression algorithm, (d) New recursive universal codes of the positive integers. (a)有歪みユニバーサル圧縮符号の冗長性解析,(b)画像圧縮におけるBit Tree Weighting法の確立,(c)ブロックソートデータ圧縮法に対する理論的性能評価,(d)新しい再帰的な正整数のユニバーサル符号化法の提案とその理論的性能評価
