Abstract: The invention provides a radio communication method and a radio communication system which allow data transmission in a wide band regarding a modem modulation signal as a speech signal and allow communication at a high transmission speed without deterioration of the data quality. When a base station receives an analog signal (facsimile or data modem modulation signal) from a public network, a CS switch section connects an analog circuit interface section to a CS-PCM/CODEC section. The CS-PCM/CODEC section modulates the modem modulation signal into a PCM signal of 64 kbps, which is then demultiplexed into two signals equivalent to ADPCM signals of 32 kbps by a CS demultiplexing section. Thereafter, a CS channel CODEC section allocates the two signals equivalent to ADPCM signals of 32 kbps to two time slots and transmits the data through two radio circuits. A base station performs demodulation of received data into an analog signal by a processing procedure reverse to that by the base station.

Abstract: A process for producing 1,3-dioxin-4-one derivatives having a lower alkyl group at 2-position and useful as a starting raw material for prostaglandins, with a high yield is provided, which process comprises reacting formyl Meldrum's acid with a lower aliphatic carbonyl compound of 2 to 4 carbon atoms in a solvent containing the carbonyl compound at 100.degree. to 120.degree. C., while portionwise adding the acid into the solvent, the total quantity of the acid added being 0.2 mol or less per liter of the solvent.