A robust multichannel sound reproduction system that utilizes the relationship between the width of the actual control area and the control frequency of the control points is proposed. The reproduction accuracy of a conventional sound reproduction system is reduced by room environment variations when fixed inverse filter coefficients are used. This tendency becomes more significant when control points are arranged more closely. To resolve this problem, the frequency control band at every control point is switched to avoid degrading the reproduced sound in low frequencies, so the pass band range of the control points at both ears is only high-range. That of the other control points is the entire control range. Numerical simulation with real environmental data showed that improvement of the reproduction accuracy is about 6.1 dB on average, even with a temperature fluctuation of 5C as an environmental variation in the listening room.

An 85 ns 16 Mb CMOS EPROM has been realized. It can be hard-ware configured as either 1 M 16 bits or 2 M 8 bits by controlling an input signal. An unique redundancy circuit, which includes two types of PROM cell fuses, allow testing the device completely before assembly. Bit-line division and tungsten polycide wordline are keys to achieve an 85 ns access time. A scaled EPROM cell of 3.6µm is realized with a 0.6 µm N-well CMOS technology with trench-self-aligned isolation and oxide-nitride-oxide interpoly dielectrics. The chip size is 7.1 17.1 mm.

The applicability of Dynamic Channel Assignment methods to a Reuse Partitioning system in cellular radio systems is investigated in this paper. The investigations indicate that such a system has a tendency to increase the difference between blocking probability for the partitioning two coverage areas in comparison with the conventional Reuse Partitioning system employing Fixed Channel Assignment method. Two schemes using new Channel Rearrangement algorithms are also proposed in order to alleviate the difference as a disadvantage which gives unequal service to the system. The simulation results show that the proposed schemes are able to reduce the difference significantly while increasing the carried traffic by 10% as compared with the conventional system.