Method for executing handover in a radio extension of an ATM network
First Claim
1. A method for executing a handover in a data transmission system comprising a switch, a first access point, a second access point and a mobile terminal, and wherein data is transmitted in cells of a determined size, in which method, prior to the handover, cells are transferred from said switch to said first access point and therefrom by radio connection to said mobile terminal, and after the handover from said switch to said second access point and therefrom by radio connection to said mobile terminal, in which case said switch informs said first access point as to which is the last cell transmitted from the switch to the first access point, wherein said first access point checks whether all cells forwarded from the switch to the first access point prior to the handover were successfully transferred to said mobile terminal, whereafteras a response to the observation of the first access point that all cells forwarded from the switch to the first access point prior to the handover were successfully transmitted to said mobile terminal, said first access point acknowledges successful downlink transmission to said mobile terminal, which as a response to said acknowledgement further informs the second access point that the downlink transmission via the first access point has succeeded, andas a response to the observation of the first access point that not all cells forwarded from the switch to the first access point prior to the handover were successfully transmitted to said mobile terminal, said first access point directs those cells that were not successfully transmitted to said mobile terminal to be forwarded to the second access point.
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Accused Products
Abstract
In the handover of a radio extension of an ATM network there are used markers that are located at fixed locations in the ATM cell stream in order to indicate the ending of an uplink and downlink cell stream, so that the switching of cell streams can be carried out in a synchronised fashion, and cells are not lost and their relative order does not change. If a downlink data transmission via the old access point succeeds, the old access point attaches to the last forwarded information field a notice of closing the traffic, in which case the mobile terminal transfers the information of successful transmission to the new access point. In another case, the old access point sends the unforwarded cells to the new access point and terminates the transaction with the same marker that generally indicates the end of a downlink cell stream.
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Citations
8 Claims
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1. A method for executing a handover in a data transmission system comprising a switch, a first access point, a second access point and a mobile terminal, and wherein data is transmitted in cells of a determined size, in which method, prior to the handover, cells are transferred from said switch to said first access point and therefrom by radio connection to said mobile terminal, and after the handover from said switch to said second access point and therefrom by radio connection to said mobile terminal, in which case said switch informs said first access point as to which is the last cell transmitted from the switch to the first access point, wherein said first access point checks whether all cells forwarded from the switch to the first access point prior to the handover were successfully transferred to said mobile terminal, whereafter
as a response to the observation of the first access point that all cells forwarded from the switch to the first access point prior to the handover were successfully transmitted to said mobile terminal, said first access point acknowledges successful downlink transmission to said mobile terminal, which as a response to said acknowledgement further informs the second access point that the downlink transmission via the first access point has succeeded, and as a response to the observation of the first access point that not all cells forwarded from the switch to the first access point prior to the handover were successfully transmitted to said mobile terminal, said first access point directs those cells that were not successfully transmitted to said mobile terminal to be forwarded to the second access point.
Specification