Method and arrangement for controlling cell change and a terminal of a cellular system
First Claim
1. A method for controlling a cell change in a service network, comprisinga terminal performs neighbour cell measurements for a cell change,the network makes a cell change decision based on said measurement results, network load and the terminal'"'"'s service need, andthe network sends to the terminal a cell change order instructing the terminal to switch over to a new cell,characterized in that if the new serving cell assigned to the terminal in the cell change order is a cell, the timing information of which is unknown to the terminal, after neighbour cell measurements, the cell change will not take place, but the terminal will send to the base station a cell change failure message instead of attempting a cell change.
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Accused Products
Abstract
The invention relates to an improved method and arrangement for controlling a cell change performed by a terminal of a cellular radio system. In particular the invention relates to a cell change in a situation where the terminal is connected to a special service provided by its current cell, e.g. to the GPRS service (General Packet Radio Service). An essential idea of the invention is that in conjunction with a cell change order a base station sends to the terminal information about whether the terminal is allowed not to carry out the cell change order if the terminal does not know the timing information of the new cell assigned to it. This information is advantageously sent in a signalling message of a certain service, such as the GPRS service. It is an advantage of the invention that a terminal connected to a certain service will not make unnecessary cell change attempts which are doomed to fail. The invention helps direct the cell change in such a manner that the load caused by possible repeated cell change attempts on the terminal and radio signalling is low.
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Citations
28 Claims
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1. A method for controlling a cell change in a service network, comprising
a terminal performs neighbour cell measurements for a cell change, the network makes a cell change decision based on said measurement results, network load and the terminal'"'"'s service need, and the network sends to the terminal a cell change order instructing the terminal to switch over to a new cell, characterized in that if the new serving cell assigned to the terminal in the cell change order is a cell, the timing information of which is unknown to the terminal, after neighbour cell measurements, the cell change will not take place, but the terminal will send to the base station a cell change failure message instead of attempting a cell change.
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8. A method for controlling a cell change in a service network, comprising
a terminal performs neighbour cell measurements for a cell change, the network makes a cell change decision based on said measurement results, network load and the terminal'"'"'s service need, and the network sends to the terminal a cell change order instructing the terminal to switch over to a new cell, the cell change order includes an information element which gives the terminal a right not to perform the cell change if the terminal does not know the timing information of the new cell assigned to it, wherein, if the new serving cell assigned to the terminal in the cell change order is a cell, the timing information of which is unknown to the terminal, after neighbour cell measurements, the cell change will not take place, but the terminal will send to the base station a cell change failure message instead of attempting a cell change, and wherein, the service network is a GPRS network and the information enabling the cancellation of the execution of the cell change order is transmitted in a signalling message to the terminal at least partly in the form of the following information elements: <
Packet Cell Change Order message content>
;
;
=<
PAGE_MODE ;
bit(2){ {0<
Global TFI ;
Global TFI IE>
>|10<
TLLI;
bit (32)>
}{0-Message escape {IMMEDIATE_REL;
bit><
ARFCN;
bit (10)<
BSIC;
bit (6)<
NC Measurement Parameters;
<
NC measurement Parameters struct>
>Packet_cell_change_order_options;
bit (3)><
padding bits>|<
Non-distribution part error;
bit(*) = <
no string>
>
}|<
message escape;
1 bit(*) = <
no string>
>
}|Address information part error;
bit(*) = <
no string>
>
}|<
Distribution part error;
bit(*) = <
no string>
>
.- View Dependent Claims (9)
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10. A method for controlling a cell change in a service network, comprising
a terminal performs neighbour cell measurements for a cell change, the network makes a cell change decision based on said measurement results received in a measurement report, network load and the terminal'"'"'s service need, and the network sends to the terminal a cell change order instructing the terminal to switch over to a new cell, wherein, if the new serving cell assigned to the terminal in the cell change order is a cell, the timing information of which is unknown to the terminal, after neighbour cell measurements, the cell change will not take place, but the terminal will send to the base station a cell change failure message instead of attempting a cell change, the message being a “ - Packet cell change failure”
message, andwherein, the service network is a GPRS network and the information sent by the terminal to the base station is transmitted to the base station in the network in a signalling message at least partly in the form of the following information elements; <
Packet Cell Change Failure message content>
;
;
=<
TLLI;
bit (32)>
}<
ARFCN;
bit (10)<
BSIC;
bit (6)<
Neighbour_cell_reporting;
<
neighbour cell reporting struct><
spare padding>
.- View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
- Packet cell change failure”
- 18. A terminal in a cellular radio system, equipped with means for connecting to a certain service and comprising means for receiving signalling messages from base stations and means for performing cell specific measurements in order to find a suitable serving cell, characterized in that the terminal is further equipped with means for determining the timing information of neighbour cells and means for sending a cell change failure message to the base station of the current cell instead of trying a cell change, in the case that the timing information of the base station of the new cell assigned to the terminal in a cell change order by the serving base station is unknown to the terminal.
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22. A cellular radio system comprising base stations and associated
cells and terminals, in which system the base stations are equipped with means for conveying signalling messages between a base station and a terminal, and the terminals are adapted so as to operate at a certain service level and to convey signalling messages between a terminal and a base station, characterized in that it further comprises information, which is known to a terminal, about a set of neighbour cells of said terminal, the timing information of the base stations of which neighbour cells the terminal has determined, whereby said system is adapted so as to convey, after a cell change order addressed to the terminal, a cell change failure massage from the terminal to the base station if the timing information of a base station of a new cell assigned to the terminal in the cell change order by the serving base station is unknown to the terminal instead of trying a cell change.
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26. A terminal in a cellular radio system, equipped with transmitter for a connecting to a certain service and comprising a receiver for receiving signaling messages from base stations and a reception block for performing cell specific measurements in order to find a suitable serving cell, characterized in that it is further equipped with a control unit for determining the timing information of neighbour cells and a transmission block for sending a cell change failure message to the base station of the current cell instead of trying a cell change, in the case that the timing information of the base station of the new cell assigned to the terminal in a cell change order by the serving base station is unknown to the terminal.
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27. A method for controlling a cell change comprising:
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a terminal receiving a cell change order from the network; the terminal determining whether timing information related to a new cell identified in the cell change order is available in the terminal; and if the timing information for the new cell is available, the terminal makes a cell change attempt; and if the timing information for the new cell is not available, the terminal sends a packet cell change failure message to the network that includes information on neighbouring cells for which the terminal already has timing information, wherein the network send another new cell change order based on the information included in the packet cell change failure message. - View Dependent Claims (28)
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Specification