Abstract: The invention relates to duplex radio communication systems comprising radio access units and at least one remote radio access units operating in a time asynchronous manner. The radio environment is scanned for radio links operating in a synchronous or an asynchronous manner to a particular radio communication unit. Handover to a synchronous link can be performed in a seamless manner using a single timing reference. There is also provided a method for initiating handover and roaming in an asynchronous radio environment. A call with a remote unit is handed over from a first radio access unit to a second radio access unit by suspending transmission of the remote unit at a first radio link while maintaining the transmission at this first radio link by the first radio access unit is established by the remote unit and the call is resumed at the second radio link after which the radio link is released by the first radio access unit.

Abstract: There is provided a method and an arrangement for flexible coexistence of several radio communication systems on a common radio frequency band. The radio frequency band has a larger bandwidth than the communication frequency band of the several radio communication systems. Prior to the start of a radio communication, the radio frequency band is scanned by a radio transceiver unit of a system for the detection of the presence of interference. The transceiver units are arranged to establish communication over any idle part of the radio frequency band comprising or covering the communication frequency band, thereby avoiding the need for frequency or channel planning. The invention can be used in Personal Communication Systems (PCS) or Cordless Terminal Mobility (CTM) services and Radio in the Local Loop (RLL) applications.