Digital radio communication system and primary and secondary station for use in such a system

TLDR: In this paper, the authors proposed a handover protocol based on the DECT standard, in which the original data and the copy data are stored in a cyclic buffer (SB5) so that the phase shift between the original and copy data is eliminated.

Abstract: A digital radio communication system (1) is known, for example based on the DECT standard, in which radio communication of digital speech or data between primary (BS1) and secondary (MS1) stations takes place via duplex FDMA/TDMA connection. Channel allocation therein is dynamic. If necessary because of the receiving conditions, the secondary station (MS1) can initiate a so-called handover by searching for a free channel offering better receiving conditions. In accordance with the invention, this handover is seamless. Digital speech bursts are exchanged via different time slots (ts) during a number of frames (fr), these being digital speech data and copy digital speech data. After verification that the copy data is valid, i.e. that communication has been established via a free channel, handover takes place. The original data and the copy data are stored in a cyclic buffer (SB5) so that the phase shift (d) between the original data and the copy data is eliminated. Subsequently, the channel via which the original data was transported is released. In one embodiment a speech pointer (SPP) for reading speech freely progresses along the cyclic buffer (SB5) and a radio pointer (RFP), progressing along the buffer (SB5) and controlling the writing of speech bursts, is adapted during handover to the phase shift (d) between time slots involved in the handover.