Telecommunications – Transmitter and receiver at separate stations – Having measuring – testing – or monitoring of system or part
Reexamination Certificate
2000-05-30
2003-12-02
Chin, Vivian (Department: 2682)
Telecommunications
Transmitter and receiver at separate stations
Having measuring, testing, or monitoring of system or part
C455S226100
Reexamination Certificate
active
06658235
ABSTRACT:
The present invention relates to a method for transmitting control information in a communication system comprising at least one base station subsystem and a wireless terminal, in which method a set of alternative values are defined for said control information, information is transmitted in packet form between the base station subsystem and the wireless terminal, the packets to be transmitted on a communication channel are transformed into bursts, and at least one burst formed of a packet is supplemented with at least one item of control data, wherein at the receiving state, the control data received in the burst is examined. The invention also relates to a communication system as set forth in the preamble of claim
8
, a wireless terminal as set forth in the preamble of claim
11
, as well as a base station subsystem as set forth in the preamble of claim
12
.
Appended
FIG. 1
shows a communication system implementing packet-format data transmission. This example system is a so-called GPRS packet network (General Packet Radio Service). The system consists of mobile stations MS which communicate with base transceiver stations BTS by means of an air interface (radio interface) Um. The base transceiver stations are controlled by base station controllers BSC which communicate with a mobile switching centre MSC. The base station controller BSC and the base transceiver stations BTS coupled therewith are also jointly called a base station subsystem BSS. The connection interface between the mobile switching centre MSC and the base station subsystem BSS is called an A interface. Correspondingly, the interface between the base station controller BSC and the base transceiver station BTS is called an Abis interface. The mobile switching centre MSC takes care of e.g. controlling incoming and outgoing calls like a centre for a public switched telephone network (PSTN) (not shown). Furthermore, the mobile switching centre MSC takes care of performing the operations required in mobile communication, such as controlling the location of the mobile station e.g. by means of a home location register HLR and a visitor location register VLR.
In digital mobile communication systems, the radio connection has typically been a so-called circuit-switched connection, which means that the resources allocated for each mobile station for a call are reserved for the whole time of the connection solely for this mobile station. The general packet radio service GPRS is a new service designed for digital mobile communication systems. This general packet radio service GPRS is designed particularly for GSM systems. A corresponding packet radio service in the North American D-AMPS system is called CDPD.
The general packet radio service GPRS is a new service under development in the GSM mobile communication system. The appended
FIG. 1
shows connections of a telecommunication network in a packet-switched GPRS service. The main element for GPRS services in the network infrastructure is a GPRS support node, so-called GSN. It is a mobility router which implements the coupling and cooperation between different data networks, e.g. to a public switched packet data network PSPDN via connection Gi or to a GPRS network of another operator via a connection Gp, mobility management with the GPRS registers via a connection Gr, and the transmission of data packets to wireless communication devices MS irrespective or their location. Physically, the GPRS support node GSN can be integrated with the mobile switching centre MSC, or it can be a separate network element based on the architecture of the data network routers. The user data is passed via a connection Gb directly between the support node GSN and the base station subsystem BSS consisting of base transceiver stations BTS and the base station controller BSC, but between the support node GSN and the mobile switching centre MSC there is a signalling connection Gs. In
FIG. 1
, continuous lines between the blocks illustrate data traffic (i.e. the transfer of speech and/or data in digital format) and broken lines illustrate signalling. Physically, the data can be passed transparently via the mobile switching centre MSC. The reference Gn represents a connection between different support nodes of the same operator. The support nodes are normally divided into gateway support nodes GGSN (Gateway GSN) and serving support nodes SGSN (Serving GSN), as shown in FIG.
1
.
Consequently, the GPRS service makes it possible to transmit information in packet form between a wireless communication device and an external data network, wherein certain parts of the mobile communication network constitute an access network.
The function of the wireless communication device MS and the support node SGSN can be divided into several layers, each of which have a different function, as shown in FIG.
2
. Transmission of data, such as control signalling and the transmission of data transmitted and received by a user, between the wireless communication device MS and the support node SGSN takes place preferably in the form of data frames. The data frame of each layer consists of a header and a data field.
Information contained in a data field can be e.g. information entered by the user of the wireless communication device or signalling data. The following is a description on the functions of the layers in the GPRS system.
In the link layer, the lowermost layer is the MAC layer (Media Access Control) which takes care of the use of the radio channel in communication between the wireless communication device MS and the base station subsystem BSS, such as channel allocation in the transmission and reception of packets.
In the lowermost layer, data transmission between the base station subsystem BSS and the support node SGSN takes place in the L2 layer (link layer) applying a link layer protocol, such as the LAPD protocol, frame relay protocol, or the like, The L2 layer can also contain quality or routing data according to the GPRS specifications. The L2 layer has properties of the physical layer and the link layer according to the OSI model.
Above the MAC layer there is the RLC layer (Radio Link Control) which serves the functions of dividing the data frames of the link layer formed by the LLC layer into packets of the radio connection (PDU, Protocol Data Unit) having a determined size to be transmitted on the radio channel, transmitting the packets, and retransmitting them, if necessary. In the GPRS system, the length of the packets is the length of one GSM time slot (ca. 0.577 ms). In the GPRS system, the packet structure of the radio connection to be applied at the time of the invention is presented more closely in the ETSI standard publication TS 101 350 v6.1.0 (1998-10): “Digital cellular telecommunications system (Phase 2+); General Packet Radio Service (GPRS); Overall description of the GPRS radio interface; Stage 2 (GSM 03.64 version 6.1.0 Release 1997)”, section 6.5.4 “Radio Block Structure”, p. 20.
The LLC layer (Logical Link Control) offers a reliable communication link between the wireless communication device MS and the support node SGSN. For example, the LLC layer supplements the message to be transmitted with error checking data, whereby attempts can be made to correct incorrectly received messages and, if necessary, the message can be retransmitted. Furthermore, data encryption and decryption takes place in the LLC layer.
The SNDCP layer (Sub-Network Dependent Convergence Protocol) is used for performing the protocol changes, compression, segmenting of the information to be transmitted, and the segmenting of messages coming from an upper layer. The SNDCP frame comprises preferably an SNDCP header and a SNDCP data field. The SNDCP header consists of protocol information (Network Service Access Point Identity, NSAPI) and SNDCP control data, such as the compressing, segmenting and encryption definitions. The SNDCP layer is used as a protocol adapter between protocols used in an upper layer (IP/X.25) and the LLC layer (link layer).
The information to be transmitted comes to the SNDCP layer pre
Oksala Jarkko
Ruohonen Jari
Savela Vesa
Tolmunen Anne
Chin Vivian
Nokia Mobile Phones Ltd.
Perman & Green LLP
Tran Tuan
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