Mobile Unit Communication System

TL;DR: In this paper, the authors propose a frame synchronizing circuit for detecting a phase between the first and second frames and synchronizing the first frames according to the detected phase, which can be used to eliminate the necessity of synchronizing operation when the mobile unit moves to the other service area.

Abstract: A mobile unit communication system comprises: mobile units; a TDMA base station for transmitting and receiving a TDMA signal having a first frame to/from mobile units within a service area thereof in a TDMA/TDD manner; and a CDMA base station adjacent to the TDMA base station, for transmitting and receiving a CDMA signal having a second frame to/from mobile units in a CDMA/TDD manner, at least one of these base stations having a frame synchronizing circuit for detecting a phase between the first and second frames and synchronizing the first and second frames according to the detected phase. Each mobile unit has a first circuit for communicating with the TDMA base station in a TDMA mode; and a second circuit for communicating with the CDMA base station in a CDMA mode. First and second frames have the same length and are synchronized to eliminate the necessity of synchronizing operation when the mobile unit moves to the other service area. A unique word attached to a framed data is commonly defined between the TDMA and CDMA signals, so that a unique word detection circuit can be used commonly. The TDMA and CDMA signals have the same frequency band, so that the antenna portion can be used commonly. The TDMA and CDMA signals have the same amount of data per channel in a frame, so that modulation and demodulation circuits can be used commonly.