Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-09-13
2002-05-07
Hunter, Daniel (Department: 2749)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S422100, C455S426100, C455S435100, C455S436000, C455S439000, C370S331000, C370S332000
Reexamination Certificate
active
06385451
ABSTRACT:
The present invention relates to a method for handing over a connection between a first and a second mobile communication network in a wireless terminal, in which method at least one data transmission connection is established for transmitting information between the wireless terminal and one said mobile communication network, wherein in the first mobile communication network, the connection type is either connection-oriented or connectionless, and in the second mobile communication network, at least two traffic classes with different transfer properties are defined, and one of them is selected for the data transmission connection of the second mobile communication network. The invention also relates to a communication system comprising at least a first and a second mobile communication network, a wireless terminal, means for activating at least one data transmission connection for transmitting information between the wireless terminal and one said mobile communication network, and means for connection handover between the first and the second mobile communication network in the wireless terminal, the first mobile communication network comprising means for establishing a connection that is connection-oriented and/or connectionless, and at least two traffic classes being defined for the data transmission connections in the second mobile communication network. The invention also relates to a wireless terminal comprising means for coupling to a communication system which contains means for establishing a data transmission connection to at least a first and a second mobile communication system, which first mobile communication system comprises means for establishing a connection that is either connection-oriented and/or connectionless, and in the second mobile communication network, at least two traffic classes are defined for the data transmission connections.
In this context, the connection handover refers to a situation when a connection is handed over from a wireless terminal which has a connection to a mobile communication network, to another mobile communication network. The wireless terminal refers, in this context, to such a data processor which also has means for establishing a data transmission connection to the mobile communication network. One example of a wireless communication device that can be mentioned is the Nokia 9000 Communicator, which comprises for instance data processing functions and mobile station functions.
In digital mobile phone systems, such as the GSM system, it is possible to transmit messages via a connection-oriented connection, such as a circuit-switched connection. A high-speed circuit-switched connection (HSCSD, High Speed Circuit Switched Data) can be mentioned as an example of such a connection-oriented connection. Furthermore, it is possible to transmit messages without setting up a circuit-switched connection. Such connectionless message transmission methods include for instance short message service SMS, unstructured supplementary service data transmission USSD, or packet based connectionless data transmission service GPRS (General Packet Radio Service). Consequently, in addition to calls and data transfer, the GSM system provides, in the form of the short message service, a service resembling a paging system. The short message service known from the GSM system is, however, much more advanced when compared with the conventional paging system. With a mobile station, it is possible not only to receive text messages but also to send them to another mobile station. Furthermore, one advantage of the short message service in the GSM system is that the transmission and reception of a short message can take place while a circuit-switched connection is open, for example during a call. Thus, the transmission of the short message does not keep the mobile station busy in the possible case of an incoming call.
In packet-switched data transmission, information is transmitted typically in bursts, wherein the interval between the transmission of bursts is influenced for instance by the quantity of information to be transmitted, and the amount of data transmission capacity allocated for the data transmission connection in question. The advantage of such a packet-switched data transmission connection when compared with a circuit-switched data transmission connection is that the data transmission channel allotted for the connection does not have to be allocated solely for one data transmission connection, but several different data transmission connections can use the same data transmission channel. Also in wireless mobile station systems, the circuit-switched data transmission connection is typically implemented in such a way that on the same radio channel, information of different connections is transmitted in different time slots (logical channels). When compared with the packet-switched connection, however, the difference is that even though there was no information in a data transmission connection to be transmitted in the time slot allocated for that data transmission connection, it cannot be utilized in any other data transmission connection either. A high-speed circuit-switched connection (HSCSD, High Speed Circuit Switched Data), which is under development for the GSM system, provides two connection types: a transparent connection and a non-transparent connection. In the transparent connection, the mobile communication network allocates resources for the connection in such a way that the connection has a substantially fixed data transmission rate and a fixed propagation delay. In the non-transparent connection, the mobile communication network can change the channel coding and data transmission rate when required by the circumstances, wherein it is possible for instance to ensure a better error correcting capability than in the transparent connection. The circuit-switched connection allocates at least one logical channel for the whole duration of the connection, which can unnecessarily consume the resources of the communication system.
As examples of the packet-switched data transmission services, the GPRS packet transmission service (General Packet Radio Service) of the GSM system and the packet transmission service of the UMTS system can be mentioned. These different systems and their different versions are not, however, fully compatible with each other. For example, the standard of the stage 1 of the GPRS packet transmission service deviates from the standard of the stage 2 and from the UMTS standard, e.g. with respect to the quality of service (QoS) alternatives that can be defined for the data transmission connection. Thus, when using a wireless terminal, the problem may arise, that a data transmission connection can only be established to a mobile communication network of a particular type, wherein the user should have a wireless terminal suitable for each mobile communication network available. To eliminate this problem, such wireless communication devices are being developed with which it is possible to establish a packet-format data transmission connection to two or more different mobile communication networks when moving from the range of one mobile communication network work to the range of another mobile communication network. In such a situation, the quality of service cannot necessarily be maintained on the same level in the mobile communication network to which a handover is attempted. For example, it should be possible to provide an audio telephone connection with high-speed packet transmission, so that speech would not become obscure and discontinuous at the receiving end. However, in the UMTS system, the aim is to achieve compatibility for instance with systems according to the stage 1 of the GPRS packet transmission service. This requires, for instance, solutions for the aforementioned problem: how to maintain the quality of service of the connection when handing over a data transmission connection from one packet network to another packet network.
It has been suggested that four different traffic classes be defined in the packet
Kalliokulju Juha
Turunen Matti
Hunter Daniel
Nokia Mobile Phones Limited
Perman & Green LLP
Woldetatios Yemane
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