Method and apparatus for handing-over a radio connection from one radio cell to another radio cell of a digital radio transmission system
First Claim
1. A method for deciding when to handing-over a radio connection when a mobile radio station (MS) moves from one radio cell into another radio cell in a digital radio transmission system with frequency-division multiplexing of adjacent radio cells and wherein co-channel radio cells are separated by different spread codes, comprising the steps of the reception quality criteria measurements to be effected in the mobile station (MS) for assigning itself one of the radio cells and consequently for the hand-over decision are effected such that additionally during the existence of a radio connection to a near base station (BS) the reception quality of the co-channel message transmission channels are measured in the mobile radio station (MS).
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Accused Products
Abstract
Base radio stations are spatially arranged in a radio transmission system in accordance with a cellular system, separating the message transmission channels from adjacent base stations being effected either by using the frequency-division multiplex method or by using the code-division multiplex method or by using a combination of these multiplex methods. In appropriately large spatial distances the same set of channels can be repeated in a further radio cell. If a mobile radio station moves during the conversation from one radio cell into another, then it is necessary to hand-over the then existing radio connection. To avoid the necessity of using additional receivers in each base station and to prevent a repeated hand-over in the event of high co-channel interferences, the measurements used for hand-over decision are effected in the mobile radio station. As part of the method the reception quality of the co-channel message transmission channels of remote base stations are additionally measured in the mobile station during the existence of a radio connection to a near base station.
328 Citations
15 Claims
- 1. A method for deciding when to handing-over a radio connection when a mobile radio station (MS) moves from one radio cell into another radio cell in a digital radio transmission system with frequency-division multiplexing of adjacent radio cells and wherein co-channel radio cells are separated by different spread codes, comprising the steps of the reception quality criteria measurements to be effected in the mobile station (MS) for assigning itself one of the radio cells and consequently for the hand-over decision are effected such that additionally during the existence of a radio connection to a near base station (BS) the reception quality of the co-channel message transmission channels are measured in the mobile radio station (MS).
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9. In a radio transmission system comprising multiple radio cells, adjacent cells being frequency multiplexed and at least some non-adjacent radio cells being co-channel, said co-channel radio cells being separated by different spread codes, the method for handing-over a radio connection via a first message transmission channel between a mobile radio station and a first base station in a first cell to a radio connection via a second message transmission channel between said mobile radio station and a second base station in an adjacent radio cell comprising the steps of:
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during the existence of a radio connection between said mobile radio station and said first base station, receiving in said mobile radio station at least one co-channel message transmission channel from at least one base station in at least one non-adjacent radio cell; measuring in said mobile radio station the reception quality of said at least one received co-channel message transmission channel; using the measured reception quality of said at least one-channel message transmission channel to decide whether to hand-over said radio connection via said first message transmission channel between said mobile radio station and said first base station to a radio connection via a second message transmission channel between said mobile radio station and a second base station in an adjacent radio cell. - View Dependent Claims (10, 11, 12, 13, 14)
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15. Mobile radio station apparatus for use in a radio transmission system comprising multiple radio cells, adjacent cells being frequency multiplexed and at least some non-adjacent radio cells being co-channel, said co-channel radio cells being separated by different spread codes,
a receiver for receiving message transmission channels from said first and second base stations and from base stations in radio cells non-adjacent to said first cell, said receiver without changing frequencies receiving a message transmission channel from said first base station and also receiving co-channel message transmission channels from base stations in radio cells non-adjacent to said first cell, measuring means for measuring the reception quality of at least one received co-channel message transmission channel, evaluation means for evaluating the measured reception quality of said at least one co-channel message transmission channel and deciding whether to hand-over a radio connection established via a first message transmission channel between said mobile radio station and a first base station to a radio connection via a second message transmission channel between said mobile radio station and a second base station.
Specification