ADAPTIVE MODULATION WITH DYNAMIC CHANNEL ASSIGNMENT (AMDCA) FOR TDMA MICROCELLULAR SYSTEMS

This paper aims at the realization of a large-capacity mobile communic ation system in the microcellular environment and proposes adaptive mo dulation with dynamic channel assignment (AMDCA) where the idea of dyn amic channel assignment (DCA) is introduced into the slow adaptive mod ulation system. In the proposed system, the received average signal po wer-to-noise/interference power ratio [C/(N+I)] is measured for each T DMA (time division multiple access) slot. The choice of idle slots in DCA and the choice of applicable modulation parameters for the slots a re made in parallel. Thus, wireless frequency resource assignment and the setting of the modulation parameters take place at the same time. This reduces the effect of the space-time distribution of the traffic in DCA and also reduces the effect of the spatial distribution of the received power in the slow adaptive modulation system on the geographi cal difference of the blocking probability of the users. The performan ce of the proposed method is evaluated by a computer simulation, and i t is verified that a capacity approximately 3 times larger can be real ized compared with conventional fixed-channel assignment in fixed QPSK in the case of voice transmission. (C) 1998 Scripta Technica.