Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-03-17
2002-08-20
Le, Thanh Cong (Department: 2684)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S466000, C370S352000
Reexamination Certificate
active
06438383
ABSTRACT:
BACKGROUND
The present invention relates to a cellular communication system supporting packet data communication and including a number of packet data nodes controlling the packet data communication in a number of packet paging areas. The packet data nodes comprise mobile station information handling means keeping information about mobile stations registered in the cells covered by the packet paging areas in turn covered by the packet data node and cell information handling means keeping information about the packet data communication channels in the cells covered by the packet data node and means for paging mobile stations.
The invention also relates to an arrangement for paging mobile stations in a stand-by state in a cellular communication system supporting packet data communication. Still further the invention relates to a method of paging mobile stations in a stand-by state in a cellular communication system supporting packet data communication.
When a mobile station has been inactive for a predetermined time period, meaning that no packets have been received from a mobile station in a packet data node or transmitted to a mobile station, the mobile station enters a so called stand-by state or a packet stand-by state. One of the reasons for introducing such a stand-by state is to increase the life time of the battery used in the mobile station. A mobile station in stand-by state does not have to inform the network, or a packet data node, when it changes from one cell to another, but it only has to inform the network when it changes packet paging area. When a mobile station is in a stand-by state, it only listens to one intermittently sent time slot for packet paging messages. A cell may for example be divided into a number of packet paging groups each of which being assigned a particular time slot for paging messages. For example, in the PDC (Pacific Digital Communication) system the mobile station then only listens to one time slot per superframe for packet paging messages. This is described in RCR STD 27F, Personal Digital Cellular Telecommunication System ARIB Standard, issued April 30th, 1991 and last revised Feb. 18th, 1997, by Association of Radio Industries and Business. If the network, or particularly the packet data node, needs to transfer information to mobile stations being in the packet stand-by state, the network, or the node, has to wake-up the mobile stations by transmitting a packet paging message to the mobile stations in the respective packet paging group time slot assigned for paging of the mobile stations. If for example the cell parameters in a cell have been changed, i.e. the number of packet data communication channels, or particularly the time slot(s) used for packet data communication in a cell, the network (the packet data node) has to broadcast information about the new cell parameters in the changed cell. A reason for changing the cell parameters, particularly the packet data communication channel resources, may be that the traffic load in the cell changes. The packet data node then uses the time slot assigned to the packet common group for such information. The packet data nodes of the network will always be informed when a mobile station enters the packet stand-by state and when there is a need to broadcast common information, such as the cell parameters, all mobile stations being in the packet stand-by state have to be woken-up. This is done by the packet data node and it transmits a packet paging message which includes information about how many packet common group time slots that will carry the broadcast information. The broadcast information is then transmitted in all time slots of the packet common groups as specified in the paging message. Thus, when information is broadcasted, the packet data node first transmits a packet paging message to wake-up all the mobile stations in the packet stand-by state in the concerned cell. The packet paging message is transmitted on all time slots belonging to the packet paging groups in the cell. The mobile stations on the other hand only listen to one time slot, namely the time slot assigned their own packet paging group. However, if a mobile station is not able to receive the packet paging message, for example depending on the actual physical location of the mobile station; it may for example be somewhere where it can not be reached by the paging message such as in a tunnel, behind a mountain or a large building or similar. Such a mobile station will consequently not receive the common information transmitted by the packet data node or by the network in general. Therefore, every mobile station which does not receive the packet paging message, will be lost by the network and all packet paging attempts by the network to find them will fail. The packet paging message is sent in one time slot in every cell in the packet paging area in which the mobile station is registered. A calculation of which-packet data communication channel, or which time slot(s) or functional channel, UPCH, which is one time slot on a packet data communication channel PPCH, is performed. The calculation of which UPCH(s) are to be used in a cell depends on the configuration of the cell, i.e. the number of packet data communication channels or particularly functional channels of which the packet data communication channels are composed. If the configuration changes, the packet data mode does not know whether the mobile station uses the old or the new configuration (which means the configuration after an update has been done in the cell i.e. after the cell has been upgraded), i.e. it does not know whether the mobile station listens to the “new” or the “old” functional channel. Thus, if the data communication resources in a cell are changed the resources to be used by a particular mobile station may be changed and if the mobile station does not receive such information, it will be lost. This is a serious drawback. The situation is different for speech and circuit switched data communication since the mobile stations within a location area continuously listen to the broadcast channel and therefore, for speech and circuit data communication the same problem does not occur.
What is needed is therefore a system, an arrangement and a method respectively through which mobile stations in a stand-by state or particularly packet stand-by state can be paged in a safe and reliable manner with a minimized risk of mobile stations being lost by the network. A system, an arrangement and a method are also needed through which paging of mobile stations can be performed in a fast and efficient manner and without wasting communication resources. A system, an arrangement and a method is also needed to enable an improvement in hitherto known system, or for providing existing systems with a safeguarding mechanism, or a fall-back, in case a mobile station has missed the broadcast information.
Therefore a cellular communication system as referred to above is provided in which each packet data node comprise mobile station information handling means keeping information about the mobile stations registered with the cells covered by the packet paging areas in turn covered by the respective packet data node and cell information handling means for keeping information about packet data communication channels in the cells covered by the packet data node. Means are further provided for calculating which packet data communication channel resources are to be used for the mobile stations after an update (upgrading) of a cell, which means that the (number of) packet data communication channel resources in a cell is altered. Means are provided for paging a mobile station in a stand-by state through the sending of a number of first paging messages from the packet data node using the packet data communication channel resources, as calculated by the calculating means, in all cells within the packet paging area in which the mobile station is registered. The system also includes means for keeping information about whether a mobile station to which a number of first paging mess
Hall Göran
Karlsson Johanna
Sundell Hans-Olof
Burns Doane Swecker & Mathis L.L.P.
Cong Le Thanh
Corsaro Nick
Telefonaktiebolaget LM Ericsson (publ)
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