Abstract: The invention relates to a method and to an arrangement for effecting base orthogonal channel hopping between mobile stations (MS1-MS3) and a base station in a radio communications system. Connections (F1-F3) having low attenuation are allotted a number of channels having high interference I (channel, t). Connections (F1-F3) that have higher attenuation are allocated a number of channels that have lower interference I (channel, t). A channel allocation means (211) in the base station functions to produce channel hopsequences which are transferred to hopsequence lists (204-206) in the mobile stations (MS1-MS3), via a control channel SACCH. The channel hopsequences are also transferred to corresponding hopsequence lists (201-203) in the base station. Attenuation of the connections (F1-F3) and interference on the channels I (channel, t) are measured continuously in the channel allocating means (211), wherein the best channels with respect to interference are used.

Abstract: In a mobile communication system, a method and an apparatus for handing off a mobile station from a first channel on a serving base station to a second channel on a target base station, the mobile station transmitting at a first transmission phase on the first channel, the second channel being ready to take over the communication with the mobile station transmitting at a second transmission phase. A device for determining a time offset is provided in the target base station and is adapted to tune in to the mobile station for determining, prior to a handoff, the time offset between the first transmission phase and the second transmission phase. Also, a device is provided for shifting, upon handoff, the transmission phase of the mobile station by the determined time offset relative to the first transmission phase.