Maintaining the composition of transferred data during handover
First Claim
1. A method for implementing a handover in a data transmission system that comprises a switch (51) and a first (40) and a second (50) base station that are affiliated with the switch, anda mobile unit (41) that is affiliated wirelessly with the base stations,and wherein the operation of the data transmission system comprises the transmission of data as cells of a given size, and the handover comprises the transmission of said cells of data first between the mobile unit (41) and the first base station (40) and, after that, between the mobile unit (41) and the second base station (50), said method comprising the steps of:
- transmitting a flow of said cells between the first base station (40) and the mobile unit (41);
detecting the first cell that is not successfully transmitted between the first base station and the mobile unit and subsequent cells that are not successfully transmitted, to determine which cells have been successfully transmitted between the first base station and the mobile unit; and
providing information from the first base station (40) to the switch (51) and/or the second base station (50) on which cells have been successfully transmitted between the first base station and the mobile unit.
3 Assignments
0 Petitions
Accused Products
Abstract
In a radio data transmission system which transmits data in cell form, the risk of cell loss or the risk of out-of-ordering during handover can be diminished by synchronizing the cell transmission between the new (50) and the old (40) base stations. The old base station (40) delivers to the new base station (50) and/or the switch (51), information on the last cell that was transmitted successfully and in the right order through the old base station, whereby the new base station continues the transmission by starting from the first failed cell. Cells need not be identified one by one if group numbering is applied in which the first or the last cell of a given group (31, 32, 33, 34) or a given counter cell is numbered, and the rest can be indicated, where necessary, by counting the distance from the numbered cell.
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Citations
18 Claims
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1. A method for implementing a handover in a data transmission system that comprises a switch (51) and a first (40) and a second (50) base station that are affiliated with the switch, and
a mobile unit (41) that is affiliated wirelessly with the base stations, and wherein the operation of the data transmission system comprises the transmission of data as cells of a given size, and the handover comprises the transmission of said cells of data first between the mobile unit (41) and the first base station (40) and, after that, between the mobile unit (41) and the second base station (50), said method comprising the steps of: -
transmitting a flow of said cells between the first base station (40) and the mobile unit (41); detecting the first cell that is not successfully transmitted between the first base station and the mobile unit and subsequent cells that are not successfully transmitted, to determine which cells have been successfully transmitted between the first base station and the mobile unit; and providing information from the first base station (40) to the switch (51) and/or the second base station (50) on which cells have been successfully transmitted between the first base station and the mobile unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A base station (40, 50), of a radio data transmission system having a plurality of base stations, for transmitting data in cell form and in a right order to a switch (51) connected to the base station by means of a wired connection and to a mobile unit (41) which is in radio link with the base station, comprising:
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means for detecting the first data cell that is not successfully transmitted between said base station and the mobile unit and subsequent data cells that are not successfully transmitted, to determine which cells have been successfully transmitted between said base station and the mobile unit; means for delivering to other base stations of said plurality of base stations the data on cells that are transmitted successfully and in the right order between said base station and the mobile unit, and means for receiving the corresponding data from said other base stations. - View Dependent Claims (17)
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18. In a radio transmission system comprising a switch (51) for controlling data in cell form, and at least two base stations (40, 50) that are affiliated with the switch, for transmitting the data in cell form between the switch (51) and a mobile unit (41), the mobile unit communicating wirelessly with the base stations, the improvement comprising:
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means for detecting the transfer of data in cell form between one of said base stations and said mobile unit and producing information regarding which cells have been successfully transferred; and means, responsive to the information produced by said detecting means, for transmitting messages concerning the successfully transferred cells between the base stations.
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Specification