US007209459B2
`
`a2) United States Patent
`US 7,209,459 B2
`(10) Patent No.:
`(45) Date of Patent:
`Apr. 24, 2007
`Kangas
`
`
`(54) TRANSMITTING CONTROL MESSAGES ON
`CONTROL CHANNELS OF PACKET DATA
`NETWORK
`
`EP
`EP
`WO
`WO
`
`1058472 A3
`1179932 Al
`WO 00/79808 A3
`WO 01/26398 Al
`
`12/2000
`2/2002
`12/2000
`4/2001
`
`(75)
`
`Inventor: Antti Kangas, Oulu (FI)
`
`(73) Assignee: Nokia Corporation, Espoo (FI)
`
`OTHER PUBLICATIONS
`
`(*) Notice:
`
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 1007 days.
`
`“The GSM System For Mobile Communications”, Mouly et al.,
`1992, ISBN:2-957190-07.
`3GPP TS 04 . 60 (relevant chapters 5.5.2.1.2 and 5.5.2.2.).
`3GPP TS 04 . 08.
`
`(21) Appl. No.: 10/156,885
`
`* cited by examiner
`
`(22)
`
`Filed:
`
`May 28, 2002
`
`(65)
`
`(30)
`
`Prior Publication Data
`
`US 2002/0176408 Al
`
`Nov. 28, 2002
`
`Foreign Application Priority Data
`
`May 28, 2001
`
`(FI) ae eeecteseeeetereeeees 20011117
`
`Primary Examiner—Hassan Kizou
`Assistant Examiner—Anthony Sol
`(74) Attorney, Agent, or Firm—Perman & Green, LLP
`
`(57)
`
`ABSTRACT
`
`A methodfor transmitting control messages of a packet data
`network in a telecommunications system which includes at
`least one cell, in which the control messages are arranged to
`be transmitted on a circuit-switched broadcast control chan-
`
`Int. Cl.
`(2006.01)
`H04Q 7/00
`nel, a packet-switched broadcast control channelandatraffic
`(52) U.S. Ch cc eceecteeeteeneeeeees 370/329; 370/338
`channel.
`In addition,
`the telecommunications
`system
`(58) Field of Classification Search ........0.00000.... None
`includes at
`least one mobile station which supports the
`See application file for complete search history.
`packet data network andis arrangedto listen to at least one
`of the broadcast control channels. First control messages to
`be transmitted on a packet-switched channel of the packet
`data network are transmitted to the mobilestationsin the cell
`
`(51)
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`5,914,942 A
`6/1999 Hassan et al. oe 370/316
`5,930,241 A *
`7/1999 Fried woe 370/328
`
`6,714,781 B2*
`.. 455/426.1
`3/2004 Pecen et al.
`.....
`
`2002/0193139 AL* 12/2002 Mildh et al... 455/552
`
`FOREIGN PATENT DOCUMENTS
`
`EP
`
`0880259 A3
`
`11/1998
`
`encapsulated inside a second control message if the cell
`supports the transmission of the connection set-up param-
`eters of the packet data network on both a circuit-switched
`broadcast control channel and a packet-switched broadcast
`control channel.
`
`8 Claims, 1 Drawing Sheet
`
`< DCCM PSI message content > ::=
`< PAGE_MODE : bit (2) >
`< PSI_MESSAGE_TYPE : bit (6) >
`< PSI_MESSAGE: < PSI message content > >
`< paddingbits >
`
` ! < Distribution part error: bit (*) = < no string > >;
`
`1
`
`DELL EX. 1013
`
`DELL EX. 1013
`
`

`

`U.S. Patent
`
`Apr. 24, 2007
`
`US 7,209,459 B2
`
`ISDN
`
`PSTN/
`
`< DCCM PSI message content > ::=
`< PAGE_MODE : bit (2) >
`< PSI_MESSAGE_TYPE : bit (6) >
`< PSI_MESSAGE: < PSI message content > >
`< paddingbits >
`
`! < Distribution part error : bit (*) = < no string >>;
`
`Fig. 2
`
`2
`
`

`

`US 7,209,459 B2
`
`1
`TRANSMITTING CONTROL MESSAGES ON
`CONTROL CHANNELS OF PACKET DATA
`NETWORK
`
`FIELD OF THE INVENTION
`
`The invention relates to packet data services of wireless
`telecommunications systems and especially to transmitting
`control messages on different control channels.
`
`BACKGROUND OF THE INVENTION
`
`The progress in wireless data transmission has more and
`more brought forth the need to transmit wirelessly not only
`calls but also different data applications. The circuit-
`switched connections used conventionally in mobile sys-
`tems are, however, rather poorly suited for transmitting
`different burst-type data services, which is why packet-
`switched applications have also been developed for mobile
`systems. During the past few years, GSM 2+phase stan-
`dards, in which the new packet-switched data transmission
`service GPRS (General Packet Radio Service)
`is also
`defined, have been drafted for the European digital GSM
`(Global System for Mobile communication) mobile net-
`work,for instance. GPRSis a packet radio network utilising
`the GSM network, which endeavours to optimise data
`packet transmission by means of GPRSprotocol layers on
`the air interface between a mobile station and a GPRS
`network.
`The GSM system comprises several different, typically
`unidirectional control channels, by means of which the
`network controls the operation of mobile stations. One such
`channel is the broadcast control channel BCCH, through
`which informationis transmitted on the different cells of the
`network, such as identification information of the cell,
`identification information on the network, frequencies used
`in the cell, etc. Each base transceiver station BTS transmits
`information on a cell on a broadcast control channel ofits
`own, to which all mobile stations in the area ofthe cell listen.
`Correspondingly, specific control channels have also been
`designed for the GPRS system, one of which is the packet
`broadcast control channel PBCCH,whosetask is to transmit
`system information to all GPRS mobile stations in the cell;
`just like BCCH does in the GSM network. When a GPRS
`mobile station is
`in idle mode, no data transmission
`resources have been allocated to it and it only listens to the
`broadcast control channel BCCH and the paging control
`channel PCH ofthe cell, or to the packet broadcast control
`channel PBCCH and the packet paging control channel
`PPCH,if the cell supports this GPRS control channel. If the
`cell does not support this PBCCH channel, which will be a
`very commonsituation when GPRS networks will be built
`on top of the GSM network, the GPRS mobile station listens
`to the GSM broadcast control channel BCCH. The used
`broadcast control channel, PBCCH or BCCH,is thus defined
`according to which broadcast control channelis available at
`each time in the cell of the GPRS mobilestation.
`
`A GPRS mobile station should thus support broadcast
`control channel reception on both the PBCCH channel and
`the BCCH channel. Then,
`if the cell uses the PBCCH
`channel, the network transmits the parameters used in the
`GPRS network to the mobile stations on said PBCCH
`channel only.
`If a GPRS mobile station is in packet transfer mode,
`control messages, which in idle mode are only transmitted
`on the PBCCH or PPCH channels, are transmitted from the
`network to the mobile station. These messages, which are
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`known as PSI messages, are then transmitted from the
`network to the mobile station on a PACCH (packet associ-
`ated control channel) channel which is an internal control
`channel, i.e. in-band channel, of a traffic channel PDTCH
`(packet data traffic channel). In such a case, the control
`messages are transmitted among the data packets that form
`the actual payload on the same physical channel.
`A problem with the arrangement described aboveis that
`if the GPRS mobile station cannot correctly receive system
`information transmitted on the PBCCH channel,
`it also
`cannot transmit or receive data packet transmissions accord-
`ing to GPRS. In the near future, when GSM networks will
`be updated to also support GPRS packet data services, a
`great risk exists that GPRS mobile stations which came out
`on the market before the PBCCH channel came to the
`networks will not work on the PBCCH channels to be built
`into the networks in the future, because it has not been
`possible to test them in field conditions. One problem inthis
`is the transmission of said PSI messages to mobile stations
`on a traffic channel, in which case all mobile stations receive
`control messages which are intended to be transmitted on
`packet-switched control channels only. Thus,
`there also
`exists a great risk that GPRS mobile stations which came out
`on the market before the GPRSservice wasinitiated will not
`work in the GPRS network after the PBCCH channels are
`
`taken into use in the new networks. The extremely signifi-
`cant drawback in this is that circuit-switched speech services
`will not work, either, in such GPRS mobile stations.
`
`BRIEF DESCRIPTION OF THE INVENTION
`
`It is thus an object of the invention to develop a method
`and an apparatus implementing the methodso as to solve the
`above-mentioned problems. The object of the invention is
`achieved by a method and system which are characterized
`by what
`is stated in the independent claims. Preferred
`embodiments of the invention are set forth in the dependent
`claims.
`
`The invention is based on the idea that if a cell supports
`the GPRSservice on both the BCCH and PBCCHchannels,
`the control messages to be transmitted to mobile stations in
`said cell on the packet-switched broadcast control channel
`and traffic channel of the GPRS network are transmitted
`
`encapsulated inside another control message. Such GPRS
`mobile stations that do not work on PBCCH channels to be
`built into the network then continue broadcast control chan-
`
`nel reception only on the BCCH channel and data packet
`transmission and reception on their traffic channel PDTCH,
`but in no case do they receive any PSI messages which cause
`error situations in them. Correspondingly, mobile station
`operating on the PBCCH channels can decode said PSI
`messages regardless of whether they are received on the
`PBCCH channel or the PDTCH channel.
`
`The method and system of the invention provide the
`advantagethat it is possible to ensure that the GPRS mobile
`stations that come out on the market before the PBCCH
`
`channel will be taken into use operate on both the broadcast
`control channel and the traffic channel in cells which will
`
`later on also use a PBCCH channel. A further advantage is
`that it is also possible to ensure that GPRS mobile stations
`to be developed later will also be capable of broadcast
`control channel reception on the PBCCH channel. A yet
`further advantage is that the PBCCH channels can be taken
`into use in GPRSnetworks as soon as network manufactur-
`ers can supply them, while at the same time makingsure that
`the old GPRS mobile stations still work.
`
`3
`
`

`

`US 7,209,459 B2
`
`3
`BRIEF DESCRIPTION OF THE FIGURES
`
`In the following,the invention will be described by means
`of preferred embodiments and with reference to the attached
`drawings, in which
`FIG. 1 shows a block diagram of the structure of the
`GSMIGPRSsystem,
`FIG. 2 shows a message according to a preferred embodi-
`ment of the invention.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`In the following, the invention will be described by way
`of example based on the GSMIGPRSsystem. The invention
`is, however, not limited to the GSM/GPRSsystem, but can,
`for instance, be applied to what is known as the third-
`generation mobile system UMTS (Universal Mobile Tele-
`communication System) which comprises functions corre-
`sponding to the GPRS system and whose mobile stations
`should also support the data transmission of the GSM/GPRS
`system.
`FIG. 1 illustrates how the GPRS system is built on the
`GSMsystem. The GSM system comprises mobile stations
`(MS) which have a radio connection to base transceiver
`stations (BTS). Several base transceiver stations BTS are
`connected to a base station controller (BSC) which controls
`the radio frequencies and channels available to them. The
`base station controller BSC andthe base transceiver stations
`BTS connected to it form a base station subsystem (BSS).
`The basestation controllers BSC are connected to a mobile
`
`services switching centre (MSC) which takes care of con-
`nection establishment and call routing to correct addresses.
`In this, two databases containing information on mobile
`subscribers are used: a home location register (HLR) which
`contains information on all subscribers in the mobile net-
`work and the services they subscribe to, and a visitor
`location register (VLR) which contains information on
`mobile stations visiting the area of a given mobile services
`switching centre MSC. The mobile services switching centre
`MSCis, in turn, connected to other mobile services switch-
`ing centres through a gateway mobile services switching
`centre (GMSC)and to a public switched telephone network
`(PSTN). For a more detailed description of the GSM system,
`reference is made to the ETSI/GSM specifications and the
`book The GSM system for Mobile Communications, M.
`Mouly and M. Pautet, Palaiseau, France, 1992, ISBN:2-
`957190-07-7.
`
`The GPRS system connected to the GSM system com-
`prises two nearly independent functions, ic. a gateway
`GPRS support node GGSN and a serving GPRS support
`node SGSN. The GPRS network can comprise several
`gateway and serving support nodes, and typically, several
`serving support nodes SGSN are connected to one gateway
`support node GGSN. Both support nodes, SGSN and
`GGSN,act as routers which support the mobility of the
`mobile station, control the mobile system and route data
`packets to the mobile stations regardless of their location
`and the used protocol. The serving support node SGSN is
`connected to the mobile station MS through the mobile
`network. The connection to the mobile network (interface
`Gb) is typically established through a base station controller
`BSC which typically comprises a packet control unit PCU,
`which creates the function required by the interface Gb in
`the base station controller BSC and controls the transmission
`of data packets onwards from the base station controller. A
`task of the serving support node SGSNis to detect mobile
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`stations capable of GPRS connectionsin its service area, to
`transmit and receive data packets from said mobile stations
`and to monitor the location of mobile stations in its service
`area. The user data of all GPRS mobile stations in the service
`area of the serving support node SGSN thus goes through
`said serving support node. Further, the serving support node
`SGSN is connected to a short message switching centre
`SMSGSMCfor incoming short messages through an inter-
`face Gd, and to the home location register HLR through an
`interface Gr, and possibly to the mobile switching centre
`MSCandthe visitor location register VLR through a sig-
`nalling interface Gs. GPRS records comprising the contents
`of subscriber-specific packet data protocols are also stored in
`the home location register HLR.
`The gateway support node GGSN acts as a gateway
`between the GPRS network and an external packet data
`network PDN. External packet data networks include the
`GPRSnetwork of another network operator or the Internet.
`The gateway support node GGSN is connected to said
`packet data networks through interfaces Gp (another GPRS
`network) and Gi (other PDNs). Private local area networks
`are typically connected to one of said packet data networks
`through a router. Data packets transmitted between the
`gateway support node GGSNandthe serving support node
`SGSN are always encapsulated according to the GPRS
`standard. The gateway support node GGSNalso contains
`PDP (Packet Data Protocol) addresses and routing informa-
`tion, i.e. SGSN addresses, of the GPRS mobile stations. The
`routing information is used to link data packets between an
`external data packet network and the serving support node
`SGSN. The GPRS backbone network between the gateway
`support node GGSNandthe serving support node SGSNis
`a network utilising the IP protocol, either IPv4 or IPv6
`(Internet Protocol, version 4/6).
`The GSM system comprises several different, typically
`unidirectional control channels, by means of which the
`network controls the operation of mobile stations. One of
`these is the broadcast control channel BCCH,through which
`information on the different cells of the network, such as cell
`identification information, network identification informa-
`tion, frequencies used in the cell, etc., are transmitted. Each
`base transceiver station BTS transmits the cell information
`on its own broadcast control channel, to which all mobile
`stations in the area of the cell listen. Further, one control
`channel is a commoncontrol channel CCCH. CCCHcan be
`
`divided into three logical channels: a paging channel PCH,
`an access grant channel AGCH and a random access channel
`RACH. Paging messages to mobile stations, for instance in
`connection with a call set-up initiated by the network, are
`transmitted on the paging channel PCH, and onthe access
`grant channel AGCHthebasetransceiverstation allocates to
`a mobile station an SDCCH channelfor the allocation of a
`traffic channel to be used in a call. The structures of the
`paging channel PCH andthe access grant channel AGCH are
`alike and the channels are used in turn according to a certain
`scheme, i.e. never simultaneously. Said control channels are
`allocated time division frames together with other logical
`control channels from the same control channel multiframe
`structure, to which different control channels are thus mul-
`tiplexed as certain channel combinations.
`The GPRS system correspondingly has its own packet
`broadcast control channel PBCCH and packet common
`control channel PCCCH. The task of the packet broadcast
`control channel PBCCHisto transmit system information to
`all GPRS mobile stations in the cell. Similar to the GSM
`common channel CCCH, the packet common control chan-
`nel PCCCH comprises several
`logical control channels.
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`US 7,209,459 B2
`
`5
`These include a packet paging channel PPCH,packet access
`grant channel PAGCH and packet notification channel
`PNCH in the downlink direction (from the base transceiver
`station to the mobile station), and a packet random access
`channel PRACH in the uplink direction (from the mobile
`station to the base transceiver station). The packet paging
`channel PPCH is used to transmit paging messages to
`mobilestations before beginning a data packettransfer, if the
`location of the mobile station is not know at an accuracy of
`acell. On the packet access grant channel PAGCH,a mobile
`station is allocated the channel resources available for
`transfer before beginning a data packet transfer. The packet
`notification channel PNCHis usedto allocate resources for
`a point-to-multipoint (PTM) message before the PTM mes-
`sage is transmitted to a certain GPRS mobile station group.
`When a GPRS mobile station is in packet-idle mode, no
`data transmission resources are allocated to it on the traflic
`channels and it only listens to the packet broadcast control
`channel PBCCH and packet paging channel PPCH of the
`cell, if the cell supports these GPRScontrol channels. If the
`cell in question does not support these GPRScontrol chan-
`nels, said mobile station listens to the GSM control channels
`BCCHand PCH. The broadcast control channel to be used,
`PBCCHor BCCH,is thus determined by which broadcast
`control channel is available at each time in the cell of the
`GPRSmobile station.
`
`If the packet broadcast control channel PBCCHis used,
`the network transmits on the PBCCH channel at regular
`intervals PSI (packet system information) messages which
`the GPRS mobile station receives regularly. Different types
`of PSI messages, such as 1, 2, 3, 3bis, 4 and 5, are used on
`the PBCCH channel. A PSI] message can also be transmit-
`ted on the PPCH channel. From the PSI messages of the
`PBCCH channel,
`the mobile station MS can deduce,
`whether it can set up a packet data link in the cell in question
`and what parameters it should use to set up the connection
`and to operate in the cell. The most important one of these
`messages is the PSII message, by means of which the
`network notifies what the situation is at each time concern-
`ing packet data service support and what the sequencing of
`the PSI messages to be transmitted is. The PSI] message
`comprises parameters PBCCH_CHANGE_MARK and
`PSI_CHANGE_FIELD, by means of which changes
`occurred in the content, update frequency and deletions/
`additions of the PSI message can be updated in such a
`manner that by increasing the parameter values in connec-
`tion with the changes, the mobile stations are directed to
`update from the network the changed PBCCHvalues. This
`way, it is possible to force all mobile stations in the cell to
`update their PBCCH information at the same time.
`The broadcast control channel BCCH can be used when
`the PBCCHchannels is not available in the cell in question
`or when it is necessary to ensure connection to the network
`in a situation in which PBCCHis removed for some reason
`or its location in the cell changes. A mobile station then
`listens on the BCCH channel to SI (system information)
`messages at regular intervals, and especially to the S113
`message which enables the transmission of the necessary
`GPRS parameters to mobile stations. The parameters are
`then transmitted that are required for setting up a GPRS
`connection in a cell which has no PBCCH channel.
`
`A GPRS mobile station should thus support broadcast
`control channel reception on both the PBCCH channel and
`the BCCH channel. In accordancewith the above,if the cell
`uses the PBCCH channel, the network transmits the param-
`eters to be used in a GPRSconnection to the mobile stations
`only on said PBCCH channel. On the other hand, if the
`GPRSmobile station cannot receive correctly system infor-
`mation transmitted on the PBCCH channel, neither can it
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`transmit or receive a data packet transmission according to
`GPRS. In such a case, using voice services may also be
`prevented. When the updating of GSM networksis started in
`the near future so as to make them also support the GPRS
`packet data service, but only on the BCCH and CCCH
`channels, a very high risk exists that GPRS mobile stations
`which came out on the market at the initial stage of the
`GPRSservice will not work on the PBCCH channels to be
`built later into the network, since it has not been possible to
`test them in field conditions.
`This can be avoided in such a manner that if a cell
`supports the GPRSservice on both the BCCH channel and
`the PBCCH channel, the network is directed to transmit the
`parameters needed for a GPRS connection to GPRS mobile
`stations on both broadcast control channels. The GPRS
`mobile stations which do not work on PBCCH channels to
`be built in the network then continue broadcast control
`channel reception on the BCCH channel only and paging
`message reception on the PCH channel, and through them
`obtain the parameters required for using the GPRSservice in
`spite of the fact that the cell may simultaneously also use the
`packet broadcast control channel PBCCH. All parameters
`related to the GPRSservice are transmitted on the BCCH
`channel as if the PBCCH channel wasnotat all in use. On
`the other hand, the GPRS mobile stations to be developed
`later will also be capable of broadcast control channel
`reception on the PBCCH channel and packet paging mes-
`sage reception on the PPCH channel. This property, in which
`the network is capable of transmitting control commands
`related to connection set-up parameters of a packet data
`service on both circuit-switched and packet-switched con-
`trol channels can be referred to by the term DCCM (dual
`control channel mode), for instance. This way, the PBCCH
`channels can be taken into use in GPRS networks as soon as
`network manufacturers can supply them, while at the same
`time making sure that that the GPRS mobile stations on the
`market now still work. The mobile stations which can
`change overto receiving the connection set-up parameters of
`a packet data service on the PBCCH channel, even though
`the network also transmits them on the BCCH channel, and
`change overto listening to the PPCH channel, can be called
`DCCMmobile stations. Mobile network cells, in which the
`parameters related to the GPRSservice are transmitted on
`both the BCCH channel and the PBCCH channel, can
`correspondingly be called DCCMcells.
`A corresponding problem is, however, accentuated in a
`situation where a GPRS mobile station is in packet transfer
`mode. In such a case, control messages, PSI] messages in
`particular, can also be transmitted from the network to the
`mobile station on a PACCH (packet associated control
`channel) channel which is an internal control channel,i.e.
`in-band channel, of a traffic channel PDTCH (packet data
`traffic channel). In such a case, the control messages are
`transmitted among the data packets that form the actual
`payload on the same physical channel. These messagesare,
`however, only intended for GPRS mobile stations, which
`can listen to the packet control channel, i.e. DCCM mobile
`stations, for example. It is, however, possible that a GPRS
`mobile station of an older model, which as described above
`is listening to the BCCH/CCCHchannels, mayreceive on its
`traffic channel PDTCH messages intended for the packet-
`switched control channels PBCCH/PCCCH that it cannot
`decode, in which case the mobile station encounters an error
`situation and cannot operate in said cell.
`This can, however, be solved by transmitting to mobile
`stations in such a DCCM cell the control messages to be
`transmitted on the packet-switched channels, i.e. either on
`separate control channels (PBCCH/PCCCH)or on the in-
`band channel (PACCH) of the traffic channel (PDTCH),
`encapsulated inside another control message. In such a case,
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`US 7,209,459 B2
`
`7
`is possible to attach to said second control message,
`it
`typically PSI message, a field indicating encapsulation that
`mobile stations which do not support the DCCM function-
`ality cannot recognise and thus they will not even try to
`decode this control message, whereas DCCM mobile sta-
`tions will recognise said field in the control message and can
`decode this control message encapsulated inside said second
`control message. This way, it is also preferably possible to
`ensure a correct reception of all control messages in DCCM
`cells regardless of whether the control messages are trans-
`mitted on separate control channels or on the in-band
`channel of the traffic channel and whether the receiving
`mobile station supports the DCCM functionality or not.
`FIG. 2 shows an arrangement according to a preferred
`embodiment of the invention, by means of which this
`reception of PSI messages on the PBCCH and PACCH
`channels by DCCM mobile stations only can be imple-
`mented using PSI message encapsulation. So that only
`DCCM mobile stations would receive these messages, but
`the phones that have comeout on the market earlier would
`not, PSI messages in a DCCMcell are encapsulated inside
`a DCCM PSI message. In the message shownin FIG.3, the
`type of the PSI message to be encapsulated is defined in a
`PSI_LMESSAGE_TYPEfield and the actual PSI message to
`be encapsulated is attached to a PSI_LMESSAGEfield. The
`mobilestations that do not support the DCCM functionality
`then do not recognise the messages and reject them, whereas
`the DCCM mobile stations recognise them.
`Because the network encapsulates all PSI messages to be
`transmitted in the above-mentioned manner, the implemen-
`tation of network elements is simplified as compared with a
`situation where the network should separately decide on the
`encapsulation depending on whether the PSI message is
`transmitted on a separate control channel (PBCCH/PCCCH)
`or on the in-band channel (PACCH)ofthetraffic channel.
`The PSI messages are typically encoded and stored in the
`same physical storage place, whereby the method of the
`invention preferably prevents the extra separation of DCCM
`messages and PSI messages. A further advantage is that due
`to the above-mentioned encapsulation arrangement both
`DCCM mobile stations and mobile stations that do not
`support the DCCM operating mode can be allocated on the
`sametraffic channel, which enables a better optimisation of
`the network resources.
`Tt is obvious to a person skilled in the art that while
`technology advances, the basic idea of the invention can be
`implemented in many different ways. The invention and its
`embodiments are thus not
`restricted to the examples
`described above, but can vary within the scope ofthe claims.
`The invention claimedis:
`
`1. Amethodfor transmitting control messages of a packet
`data network in a telecommunications system which com-
`prises at least one cell, in which said control messages are
`configured to be transmitted on a circuit-switched broadcast
`control channel (BCCH), a packet-switched broadcast con-
`trol channel (PBCCH)anda traffic channel (PDTCH), and
`at least one mobile station which supports the packet data
`network and is configured to listen to at least one of said
`broadcast control channels, comprising:
`transmitting to the mobile stations in said cell a packet
`system information message to be transmitted on a
`packet-switched channel of the packet data network
`encapsulated inside a control message in response to
`the fact that the cell supports the transmission of the
`connection set-up parameters of the packet data net-
`work on both a circuit-switched broadcast control chan-
`
`nel and a packet-switched broadcast control channel;
`
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`8
`indicating by a field in said control message that said
`packet system information message is encapsulated
`inside said control message; and
`rejecting said packet system information message in the
`mobile station in response to the fact that said mobile
`station is configured to listen to the circuit-switched
`broadcast control channel and said control message
`comprises said field indicating encapsulation.
`2. The method as claimed in claim 1, comprising:
`transmitting the control messages to the mobile stations
`on the packet-switched broadcast control channel (PB-
`CCH).
`3. The method as claimed in claim 1, comprising:
`transmitting the control messages to be transmitted on the
`traffic channel (PDTCH)on an in-bandcontrol channel
`(PACCH)ofthe traffic channel.
`4. The method as claimed in claim 1, comprising:
`decoding said packet system information message in the
`mobile station in response to the fact that said mobile
`station is configured to listen to the packet-switched
`broadcast control channel and said control message
`comprises said field indicating encapsulation.
`5. A telecommunications system which comprises a
`packet data network and at least one cell, in which control
`messages are configured to be transmitted on a circuit-
`switched broadcast control channel
`(BCCH), a packet-
`switched broadcast control channel (PBCCH)anda traffic
`channel (PDTCH), and at least one mobile station which
`supports the packet data network and is configured to listen
`to at least one of said broadcast control channels, wherein
`a packet system information messageto be transmitted on
`a packet-switched channelof the packet data network is
`configured to be transmitted to mobile stations in said
`cell encapsulated inside a control message in response
`to the fact that the cell supports the transmission of the
`connection set-up parameters of the packet data net-
`work on both a circuit-switched broadcast control chan-
`nel and a packet-switched broadcast control channel;
`said control message comprises a field which indicates
`that said packet system information is encapsulated
`inside said control message; and
`said packet system information message is configured to
`be rejected by the mobilestation in response to the fact
`that said mobile station is configured to listen to the
`circuit-switched broadcast control channel and said
`
`control message comprises said field indicating encap-
`sulation.
`
`6. The telecommunications system as claimed in claim 5,
`wherein the control messages to the mobile stations are
`configured to be transmitted on the packet-switched broad-
`cast control channel (PBCCH).
`7. The telecommunications system as claimed in claim 5,
`wherein the control messages to be transmitted onthetraffic
`channel (PDTCH) are configured to be transmitted on the
`in-band control channel (PACCH)ofthe traffic channel.
`8. The telecommunications system as claimed in claim 5,
`wherein
`
`said packet system information message is configured to
`be decoded in the mobile station in responseto the fact
`that said mobile station is configured to listen to the
`packet-switched broadcast control channel and said
`control message comprises said field indicating encap-
`sulation.
`
`6
`
`