Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
2000-01-13
2004-09-21
Duong, Frank (Department: 2666)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S469000, C370S474000, C370S476000
Reexamination Certificate
active
06795435
ABSTRACT:
BACKGROUND OF INVENTION
The present invention relates to a method according to the preamble of the appended claim
1
for transmitting data transmission flows preferably in a packet format between communication devices in a communication system comprising at least one data network. The invention also relates to a data transmission system according to the preamble of the appended claim
8
, comprising at least a first and a second communication device, and means for activating at least one data transmission connection in order to transfer information between said communication devices. Furthermore, the invention relates to a wireless communication device according to the preamble of the appended claim
12
.
In this specification, the term communication device refers for example to such data transmission devices by means of which it is possible to set up a data transmission connection to a data network in order to transmit and receive information. In the data transmission connection, information is transferred between different communication devices. The information to be transferred can include for example files, audio signals, video signals, or combinations of these (multimedia information). In this specification, the term data transmission flow refers to transmission of information related to the same source of information. For example in the transmission of a call, the transfer of an audio signal constitutes one data transmission flow. Correspondingly, to transfer multimedia information which contains audio and video information, advantageously two data transmission flows are thus established.
The data network can be composed of numerous communication devices. At present, for example the Internet data network comprises tens of millions of communication devices. Each communication device has an address which identifies the communication device in the Internet data network. This address information is used to guide different data transmission flows to the correct communication device. Such a data network is composed of routers, which are communication devices capable of routing the received data transmission flows forward. Terminals, in turn, are communication devices capable of transmitting and receiving data transmission flows. In the data network, the data transmission flows transmitted from a transmitting terminal can travel through several routers to the receiving terminal.
The Internet is made to function by determining specific telecommunication standards and protocols, such as TCP (Transfer Control Protocol), UDP (User Datagram Protocol), IP (Internet Protocol) and RTP (Real time Transport Protocol), which are used to control data transmission between numerous parts of the Internet data network. The TCP and the UDP are concerned with preventing and correcting data transmission errors of data transmitted in the Internet data network, the IP is concerned with the structure and routing of the data, and the RTP is designed for real-time data transmission in the Internet data network. The Internet protocol versions used at present are lPv4 and lPv6.
In multimedia applications, for example video image information, audio information and data information is transmitted between a transmitting and a receiving multimedia terminal. The information is transmitted for example by means of the Internet data network or another communication system, such as a general switched telephone network (GSTN). The transmitting multimedia terminal is for example a computer, generally also known as a server, of a company providing multimedia services. The data transmission connection between the transmitting and receiving multimedia terminal is set up in the Internet data network via routers. Information transfer can also be duplex, wherein the same multimedia terminal functions both as a transmitting and a receiving terminal.
The source of information can be advantageously a video application, an audio application, a data application, or a combination of these, all of which will be included within the common term multimedia application in this specification. In a multimedia application, the user of a multimedia terminal selects the location of the desired information source, wherein the system sets up a data transmission connection between the selected retrieval location of the information and the multimedia terminal of the user. In data transmission, data frames are typically used in which the information is transmitted in digital format. Separate data frames are advantageously formed of different types of information sources, and in some cases, information from two or more sources of information may be included in a single data frame. The data frames are transmitted in the communication system to the multimedia terminal of the user. In practical applications, these data frames are temporally interleaved, wherein the actual data transmission flow is composed of temporally separated data frames of various applications. There are also systems under development, in which a separate logical data transmission channel is allocated for different types of applications and in which e.g. different frequencies, or in CDMA-based systems, different code keys are used. In practice, the data transmission capacity of such communication systems is limited e.g. due to the fact that the data transmission channel is physically band restricted, and there may exist several data transmission connections simultaneously, wherein it is not possible to allow any data transmission connection to use the capacity of the entire communication system. In mere audio applications, this does not usually constitute a significant drawback because the amount of information to be transferred is relatively small. However, in the transmission of video information, this restricted band sets great demands for the communication system.
The use of multimedia applications has also been under development in low bit rate communication systems, wherein the data transmission rates are in the order of 64 kbit/s or lower.
FIG. 1
a
illustrates data transmission between two terminals MS, RH. Correspondingly,
FIG. 1
b
shows the different layers in the protocol stack of the data transmission connection. It is presumed in the example that the information is transmitted via a single router R, but it is obvious that in practice there may be a considerably larger number, even several dozens of routers. The information to be transferred is composed in an application, wherein the term application layer AL will be used for the functions of this layer. In the application layer, the information can be arranged according to a protocol, or it can be in a format recognized by the application. In the transmitting terminal, the information is transferred from the application layer to a lower network layer NL in the protocol stack, or directly to a link layer LL. In the network layer, the information of the application layer is arranged into frames according to any network layer protocol, for example into frames of the Internet protocol (IP). The purpose of the network layer is, for instance, to supplement the frames with routing information. The frames of the network layer protocol are transferred to the link layer, in which the frames are arranged into link layer frames. These link layer frames are channel coded to enable the actual data transmission between the communication devices. The term physical layer is used for this data transmission layer. The physical layer can comprise wired communication devices, such as a landline telecommunication network, and wireless communication devices, such as a mobile communication network, infrared communication devices, or inductive communication devices. Thus, the data transmission can take place via various data transmission channels. However, between two communication devices one data transmission mode is typically used. In the router, the received information of the physical layer is converted into link layer frames. In some routers, it is possible to route the frames further already on the basis of the information
Jouppi Jarkko
Kalliokulju Juha
Duong Frank
Nokia Mobile Phones Ltd.
Perman & Green LLP
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