We propose a dynamic assignment method of radio channels using their qualit
ies and data packet sizes. In this method, a high quality channel is assign
ed for long packets and a low quality channel is assigned for short packets
. Assuming a packet transfer method based on PHS (Personal Handy System) pr
ocedure, the transfer speed and delay characteristics are investigated by c
omputer simulation and compared with conventional method (i.e. random assig
nment). Both the transfer speed characteristics and delay performance are i
mproved under light traffic load.