US 6,879,823 B1
`(10) Patent No:
`«2 United States Patent
`Raaf
`(45) Date of Patent:
`Apr.12, 2005
`
`
`US006879823B1
`
`(54) MOBILE STATION, BASE STATION AND
`METHOD FOR DATA TRANSMISSION IN A
`MOBILE RADIO SYSTEM
`
`.
`:
`(75)
`Inventor: Bernhard Raaf, Munich (DE)
`.
`:
`:
`(73) Assignee: OE Aktiengesellschaft, Munich
`
`.
`
`:
`(*) Notice:
`
`:
`Lo,
`.
`Subject to any disclaimer, the term ofthis
`patent is extended or adjusted under 35
`US.C. 154(b) by 0 days.
`
`(21) Appl. No.:
`.
`(22) PCT Filed:
`
`09/831,179
`
`Nov. 2, 1999
`
`(86) PCT No.:
`$371(1),
`(2), (4) Date: May 4, 2001
`
`PCT/DE99/03484
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`5,475,870 A * 12/1995 Weaveret al... 455/67.11
`5,933,465 A *
`8/1999 Ozaki v.ccccesesseeseseeeene 375/346
`6,085,107 A *
`7/2000 Persson et al.
`............. 455/522
`6,389,300 B2 *
`5/2002 Raaf veecssscsssssseeceessee 455/561
`
`FOREIGN PATENT DOCUMENTS
`
`WO
`WO
`WO
`
`WO 92/10886
`WO 94/29981
`WO 97/25827
`
`6/1992
`12/1994
`T/A997
`
`* cited by examiner
`
`Primary Examiner—Allan Hoosain
`(74) Attorney, Agent, or Firm—Bell Boyd & Lloyd LLC
`(57)
`ABSTRACT
`
`(30)
`
`A mobile station, base station and method for data trans-
`(87) PCT Pub. No.: W0O00/27150
`mission in a mobile radio system, wherein for the purpose of
`PCT Pub. Date: Mav
`11, 2000
`observing GSM base stations,
`interruption phases are
`, vay
`inserted in a UMTStransmission. To reduce the number of
`Foreign Application Priority Data
`
`these interruption phases, the maximum effective duration of
`the interruption phasesis chosen to be shorter than is needed
`+ 198 50 866
`(DE)....
`Nov. 4, 1998
`tPHon
`Pp
`Iss
`>
`(DE)
`ceesssssssssesssseessssseesessneessnsecs 198 51 600
`Nov. 9, 1998
`under optimum transmission conditions for secure detection
`of a data packet which is to be detected and is sent from a
`(SL) Ute C0 eee ecececsesscsseeseeseeseeneeneeneens HO04B 17/00
`(52) US. Ch. cecccccccnes 455/414; 455/53.1; 455/56.1,;|GSM basestation. A shrewd choice of parameters provides
`455/115; 455/415; 455/67.1
`a better ratio of effort (effective duration of the interruption
`(58) Field of Search .....cccccccccccssssssseee 455/414, 412,
`Phase) to result (detection probability).
`455/413, 53.1, 56.1, 67.1; 375/316, 346,
`348
`
`17 Claims, 2 Drawing Sheets
`
`
`
`PSTN/ISDN
`{
`
`AMAZON.COM,INC., etal.
`
`EXHIBIT 1010
`
`1
`
`

`

`U.S. Patent
`
`Apr. 12, 2005
`
`Sheet 1 of 2
`
`US 6,879,823 B1
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`PSTN/ISDN
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`2
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`

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`U.S. Patent
`
`Apr. 12, 2005
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`Sheet 2 of 2
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`US 6,879,823 B1
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`FIG 2
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`3
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`US 6,879,823 B1
`
`1
`
`MOBILE STATION, BASE STATION AND
`METHOD FOR DATA TRANSMISSION IN A
`MOBILE RADIO SYSTEM
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`The present invention relates to a base station, a mobile
`station and a method for data transmission in a communi-
`cation system,in particular in a CDMA mobile radio system,
`where the data, structured in frames,is transmitted such that
`a mobile station is able to perform other functions;
`in
`particular, to carry out tests using a reception device, during
`one or more interruption phases in which it interrupts the
`reception (of the previous source or of the data from the base
`station) and/or the processing of received data or sending.
`“Transmission”is to be understood as sending and/or receiv-
`ing below.
`2. Description of the Prior Art
`In communication systems, data (for example voice data,
`image data or system data) is transmitted on transmission
`links between base stations and mobile stations. In radio
`communication systems, this is done using electromagnetic
`waves via an air or radio interface. In this context, carrier
`frequencies are used which are situated in the frequency
`band provided for the respective system. In the case of the
`GSM (Global System for Mobile Communication),
`the
`carrier frequencies are in the range of 900 MHz. For future
`radio communication systems,
`for example the UMTS
`(Universal Mobile Telecommunication System) or other
`third generation systems, frequencies in the frequency band
`of 2000 MHzare provided.
`Particularly in future CDMA systems, a base station
`basically sends continuously in the downlink direction, for
`example, that is to say in the direction from the base station
`to a mobile station. The data transmitted during sending is
`usually structured in frames which each have a prescribed
`length. Particularly with different services such as voice data
`transmission and video data transmission, the frames may
`also have different structures and lengths. The structure
`and/or length of each frame in a continuousseries of frames
`is prescribed and/or is recognized by the mobile station,
`however.
`
`Particularly in cellular mobile radio systems, the mobile
`station occasionally also needs to perform functions other
`than data reception which cannot be performed at the same
`time, at least during the operation of only a single reception
`device. By way of example, from time to time the mobile
`station in a radio communication system of cellular design
`in which the base stations in various cells send on different
`
`frequencies needs to test whether it is able to receive radio
`signals from another base station with good reception qual-
`ity. For this purpose, the mobile station sets its reception
`device to a frequency other than the frequency on whichit
`currently receives data.
`In order to be able to send from the base station to the
`
`it has already been
`interruption,
`mobile station without
`proposed that the mobile station be equipped with a second
`reception device.
`In practice, however,
`this solution is
`usually rejected for cost reasons.
`Another proposal is known according to which the base
`station interrupts sending at prescribed times in order to
`allow the receiving station to carry out an adjacent channel
`search (search for an adjacent base station or for particular
`data packets transmitted by these base stations, where data
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`packets also may be understood below to be
`synchronization, frequency correction or pilot signal bursts)
`using its individual reception device.
`To prevent a loss of data, the base station sends the data
`beforehandat a higher transmission rate than the fundamen-
`tally constant permanenttransmissionrate. So that this does
`not result in higher bit error rates (BER), the transmission
`poweradditionally needs to be increased during this time.
`The frequency at which the interruption phases recur and
`the length of the interruption phases depend onthe particular
`system and also on the particular operating state of the
`system. By way of example, interruption phases each having
`a length of 5 to 6 ms, respectively, are sufficient for an
`adjacent channel search by a mobile station in a radio
`communication system organized on a cellular basis.
`WO-A-97 25827 discloses a method for data transmission,
`in which interruption phases for observing an adjacent base
`station are inserted during transmission. However, provision
`is madein this case for the interruption phases to be inserted
`at regular intervals, which entails the disadvantage that the
`efficiency of the data transmission is reduced with each
`interruption phase.
`Since the losses in transmission quality also increase with
`the numberofinterruption phasesinserted,it is desirable for
`the smallest possible number of interruption phases to be
`inserted.
`
`By way of example, a GSM frame transmitted by the
`GSM base station contains eight
`timeslots which each
`contain a data packet. The data packets transmitted by the
`GSMbasestation BS2, such as synchronization data packets
`(data packets to be detected, synchronization burst), fre-
`quency correction data packets (characteristic data packets,
`frequency correction burst) and normal data packets,are all
`subordinate to the same time frame. The GSM basestations
`transmit all 10 time frames (GSM frames) 4 times and,after
`a subsequent 11 time frames (GSM frames) (51 time frames
`in total), a frequency correction data packet, and one respec-
`tive time frame later, a synchronization data packet.
`If interruption phases based on the GSM standard were
`now inserted with a period of 26 time frames (GSM frames),
`the fact that the period of 51 time frames and the period of
`26 time frames have no common denominator would cause
`a cyclic shift in the two time frame periods, so that after a
`maximum of 11 times 26 time frames, that is to say after 11
`observation frames, the sought data packet which is to be
`detected would be received if the mobile station is not too
`distant from the respective adjacent base station BS2, BS3
`or if no interference which is too intense arises during
`transmission.
`
`to
`therefore,
`invention,
`is an object of the present
`It
`specify a method for data transmission, a mobile station and
`a base station which permit second base stations to be
`reliably observed while transmission quality is good.
`SUMMARYOF THE INVENTION
`
`Accordingly, the present invention is based, in particular,
`on the concept of, contrary to the prior art, inserting inter-
`ruption phases in which the mobile station interrupts the
`transmission, in particular the reception, of the data sent by
`the first base station and/or the processing of the received
`data not with a maximum effective total duration which
`would be needed under optimum transmission conditions for
`secure detection of a data packet which is to be detected, but
`instead inserting fewer and/or shorter interruption phases.
`Complex simulations using simulation tools developed
`specially for this purpose have proved that, when the effec-
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`US 6,879,823 B1
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`4
`reduced to 91%, with a mere loss of 2% needing to be
`accepted for the detection probability in return, as well as a
`halving of the search speed in comparison with the GSM
`search speed.
`In another embodimentof the present invention, a period
`of 6 GSM frames is inserted between the start of a first
`interruption phase and the start of a first interruption phase
`and the start of a second interruption phase, and a period of
`46 GSM framesis inserted between the start of a second
`interruption phase andthe start of a third interruption phase.
`In this case, simulations have been able to show that, at
`GSMsearch speed, the maximum effective total duration of
`the interruption phases can be reduced by 9% for a com-
`paratively very small detection possibility loss of 2%.
`the
`In another embodiment of the present
`invention,
`insertion of further interruption phasesis ended,restricted or
`continued under control before the maximum effective total
`duration of the interruption phases is actually reached. To
`this end, after reception of a data packet which is to be
`detected or possibly of another data packet, indicating the
`end of the adjacent channel search, such as a characteristic
`data packet, an appropriate messageis transmitted from the
`mobile station to the first base station.
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`tive total duration of the interruption phases is shortened,
`contrary to the prior art, to a duration of a maximum of9 or
`a maximum of 10 observation frames, the effective total
`duration of the interruption phases can be reduced by a much
`greater proportion than, in return, the theoretical detection
`probability for a data packet which is to be detected
`decreases. The effect of this is that the transmission quality
`from the first base station to a mobile station is improved,
`but in return the detection probability for a data packet
`which is to be detected remains comparatively high with
`respect thereto.
`In this case, the data can be sent, by way of example, from
`the first base station to the mobile station, in which case, at
`least during particular transmission phases,
`interruption
`phases are inserted in which the first base station interrupts
`sending, and the mobile station interrupts the reception
`and/or the processing of received data, for example. In
`addition, the mobile station is switched to the reception of
`the characteristic data packets and/or data packets which are
`to be detected, which are sent cyclically by a second base
`station, and the maximum effective total duration of the
`interruption phases is shorter than would be needed under
`optimum transmission conditions for secure detection of a
`data packet which is to be detected.
`The data packets sent by the second basestation also may
`25
`Thus, while data is transmitted fromafirst base station to
`be data packets which are to be detected (synchronization
`a mobile station in the downlink direction, for example,
`data packets) or characteristic data packets (frequency cor-
`interruption phases are inserted, at least during particular
`rection data packets).
`send phases,
`in which the mobile station interrupts the
`In this context, a first transmission method, used bya first
`reception of the data sent by the first base station and/or the
`base station, may be a CDMA method, and a second
`processing of the received data and in which the mobile
`transmission method, used by a second basestation, may be
`station is switched to the reception of data packets sent by
`a GSM method.
`a second base station. Depending on a reception result for
`these data packets sent by a second basestation, information
`which influences the insertion of interruption phases is sent
`from the mobile station to the first base station.
`
`Within the context of the application, GSM frameis also
`understood to be a frame which contains 8 time slots and has
`a duration of 4.6 ms.
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`
`Within the context of the application, observation frame is
`also understood to be a minimum time period required in
`order to observe a GSM frame. In this case,
`the exact
`duration of an observation frame is implementation-
`dependent; however, in order to ensure full detection of a
`GSM frame and to allow for the time needed for changing
`over the synthesizer frequency,it is generally longer than the
`duration of a GSM frame and may thusalso have a duration
`of 9 time slots, 10 time slots (5.7 ms), 11 time slots or 12
`time slots (6.9 ms).
`Since manydifferent variants are possible for inserting the
`interruption phases for the purpose of the adjacent channel
`search, the term “maximum effective total duration of the
`interruption phases” within the context of this application
`denotes the sum ofall the interruption phases inserted as a
`maximum in order to observe an adjacent base station.
`However, this does not preclude further interruption phases
`from being inserted during subsequent repetition of the
`adjacent channel search, although a new effective total
`duration of the interruption phases is formed in this case.
`Under these circumstances,
`the individual
`interruption
`phases each may havethe duration of an observation frame,
`but also may have any other duration. The duration of an
`interruption phase also may have a multiple or a fraction of
`the duration of an observation frame. It is also possible for
`the individual interruption phases to have different dura-
`tions.
`
`In one embodiment of the present invention, a period of
`52 GSM frameslies between the start of a first interruption
`phase and the start of a second interruption phase.
`Simulations have been able to show that this allows the
`
`effective total duration of the interruption phases to be
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`In this way,it is possible for the insertion of interruption
`phases to be ended as soon as possible, and hence to be
`restricted as far as possible, as soon as sufficient information
`is known about the second base stations which are to be
`
`observed, and hence for the transmission quality to be
`improved. The effect of this is that the total duration of the
`interruption phases can be reduced further.
`Additional features and advantages of the present inven-
`tion are described in, and will be apparent from, the follow-
`ing Detailed Description of the Preferred Embodiments and
`the Drawings.
`DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 showsa basic circuit diagram of a mobile radio
`system;
`FIG. 2 showsa basic circuit diagram of a mobile station;
`and
`FIG. 3 shows a schematic illustration of the insertion of
`
`interruption phases during a send phase.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`FIG. 1 shows a cellular mobile radio network including,
`by way of example, a combination of a GSM (Global
`System for Mobile Communication) system with a UMTS
`(Universal Mobile Telecommunication System) system,
`which includes a multiplicity of mobile switching centers
`MSC whichare interlinked and set up access to a landline
`network PSTN/ISDN.In addition, these mobile switching
`centers MSC are connected to at least one respective base
`station controller BSC, which also may be formed by a data
`processing system.
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`US 6,879,823 B1
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`6
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`Each basestation controller BSC is, in turn, connected to
`The radio frequency part HF includes the transmission
`at least one base station BS. Suchabasestation BSis a radio
`device SE, having a modulator and an amplifier, and a
`station whichis able to use a radio interface to set up a radio
`reception device EE having a demodulator and likewise an
`link to other radio stations, so-called mobile stations MS.
`amplifier.
`Radio signals can be used to transmit information between
`The transmission device SE and the reception device EE
`the mobile stations MS and the base station BS associated
`are supplied with the frequency of a voltage controlled
`with these mobile stations MS within radio channels situated
`oscillator VCO using the synthesizer SYN. The voltage
`within frequency bands. The range of the radio signals of a
`controlled oscillator VCO also can be used to generate the
`base station defines, in essence, a radio cell FZ.
`system clock for clocking processor devices of the appli-
`Basestations BS and a basestation controller BSC can be
`ance.
`combined to form a base station system. In this context, the
`base station system BSSis also responsible for radio channel
`administration and allocation, data rate matching, monitor-
`ing of the radio transmission link, handover procedures and,
`in the case of a CDMAsystem, for the allocation of the
`spread code sets which are to be used, and transmits the
`signaling information required for this to the mobile stations
`MS.
`
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`the frequency bands
`In the case of a duplex system,
`provided for the uplink (mobilestation to base station) may
`be different than those provided for the downlink (base
`station to mobile station) in FDD (Frequency Division
`Duplex) systems such as the GSM system, and, in TDD
`(Time Division Duplex) systems, such as the DECT(Digital
`Enhanced Cordless Telecommunications) system, different
`time intervals may be provided for the uplink and for the
`downlink. Within the different frequency bands, an FODMA
`(Frequency Division Multiple Access) method can imple-
`ment a number of frequency channels.
`Terms and examples used within the context of this
`application also often refer to a GSM mobile radio system;
`they are in no way limited thereto, however, but rather also
`may be easily mapped onto other, possibly future, mobile
`radio systems, such as CDMAsystems,in particular wide-
`band CDMAsystems or TD/CDMAsystems, by a person
`skilled in the art using the description. First base station BS1
`is understood to be, in particular, a UMTSbasestation or a
`CDMAbasestation, second and/or third base stations BS2,
`BS3are understood,in particular, to be GSM (adjacent) base
`stations which are to be observed, and mobile station is
`understood, in particular, to be a dual mode mobile station
`designed both for receiving/sending GSM signals and for
`receiving/sending UMTSsignals or CDMAsignals, the dual
`mode mobile station also being able to be made ready for
`stationary operation, if appropriate.
`FIG. 2 shows a radio station which may be a mobile
`station MS,
`including an operating unit MMI, a control
`device STE, a processing device VE, a power supply device
`SVE, a reception device EE and a transmission device SE.
`The control device STE in essence includes a program
`controlled microcontroller MC which has write and read
`
`access to memory modules SPE. The microcontroller MC
`controls and supervises all the fundamental elements and
`functions of the radio station, in essence controls the com-
`munication and signaling flow, reacts to keypad inputs by
`executing the corresponding control procedures and is also
`responsible for transferring the applianceinto different oper-
`ating states.
`The processing device VE also can be formedbya digital
`signal processor DSP which is likewise able to access
`memory modules SPE.
`The volatile or nonvolatile memory modules SPE store
`the program data required for controlling the radio station
`and the communication flow, and also the signaling proce-
`dures in particular, appliance information,
`information
`entered by the user and information arising during the
`processing of signals.
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`For receiving and sending signals via the air interface of
`a mobile radio system, an antenna device ANTis provided.
`The radio station also may be a base station BS. In this
`case, the operating unit is replaced by a link to a mobile
`radio network, for example via a base station controller BSC
`or a switching center MSC. In orderto interchange data with
`a number of mobile stations MSat the same time, the base
`station BS has an appropriate multiplicity of transmission
`and reception devices available.
`FIG. 3 shows the frame structure of a data transmission
`with a short delay time, in particular of voice transmission
`in a UMTS (Universal Mobile Telecommunication System),
`containing twelve individual frames 1 for data transmission
`within a respective multiframe. In this case, the illustration
`shows, in particular, a send phase in the downlink from a
`first base station BS1, in particular a UMTSbasestation
`BS1,
`to a mobile station MS,
`in particular a dual mode
`mobile station MS, designed not only for receiving UMTS
`data but also for receiving GSM data packets. The state-
`ments employed below are, in essence, restricted to the
`downlink. It goes without saying, however, that the present
`invention can be introduced not only to downlink
`transmission, but also to uplink transmission.It is within the
`scope of action of a person skilled in the art to introduce the
`exemplary embodiments demonstrated below for the down-
`link to uplink transmission.
`The individual frames 1 each have a transmission length
`Tf of 10 ms, wherein the mutliframe has a transmission
`length Ts of 120 msin total. The respective fifth and sixth
`individual frames 1 have a commoninterruption phase 2
`(possibly overlapping their frame boundaries 3) which has a
`length Ti. The length Ti is 6 ms, for example. The subsec-
`tionsofthe first frame 4a, which starts before the interrup-
`tion phase 2, and of the second frame 4b, which endsafter
`the interruption phase 2, are of the same length or of the
`samesize. In the case of the exemplary embodiment shown
`in FIG. 3, voice data is being transmitted, so that a maximum
`delay of 10 ms,
`that is to say a frame length Tf, when
`evaluating the data received by the mobile station is accept-
`able. The data within a frame is sorted, coded together and
`sent superimposed on one another.
`In the exemplary
`embodiment, the transmission rate of the first frame 4a and
`of the second frame 4b is increased, in each case, such that
`the same quantity of information whichis to be sent, which
`is sent in uncompressed frames 1 over the frame length Tf,
`is sent in a time span Te=Tf-Ti/2.
`In this case, during the interruption phases, at least the
`sending of data to a particular mobilestation carrying out the
`adjacent channel search is interrupted, while sending to
`other mobile stations can be continued, this being made
`possible by the use of a multiple access method, for example
`a CDMAmethod.
`
`A GSM frame transmitted by the GSM base station
`contains eight timeslots which each contain a data packet.
`The data packets transmitted by the GSM basestation BS2,
`such as synchronization data packets (data packets to be
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`US 6,879,823 B1
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`7
`detected, synchronization burst), frequency correction data
`packets (characteristic data packets, frequency correction
`burst) and normal data packets, are all subordinate to the
`same time frame. The GSM basestations transmit all 10 time
`frames (GSM frames) 4 times and, after a subsequent 11
`time frames (GSM frames) (51 time frames in total), a
`frequency correction data packet, and one respective time
`frame later, a synchronization data packet.
`If interruption phases based on the GSM standard were
`now inserted with a period of 26 time frames (GSM frames),
`the fact that the period of 51 time frames and the period of
`26 time frames have no common denominator would cause
`
`a cyclic shift in the two time frame periods, so that after a
`maximum of 11 times 26 time frames, that is to say after 11
`observation frames, the sought data packet which is to be
`detected would be received if the mobile station is not too
`distant from the respective adjacent base station BS2, BS3
`or if no interference which is too intense arises during
`transmission.
`
`If the maximum effective total duration of the interruption
`phases is now reduced, contrary to the prior art, from 11
`observation frames to, by way of example, 10 or 9 obser-
`vation frames when observing GSM basestations during the
`call phase for a mobile station MS and a UMTSbasestation
`BS1, the data transmission within the context of the call by
`the mobile station MS via the base station BS1 can be
`improved. The associated reduction in detection probability
`is comparatively small and is thus acceptable.
`In one variant embodimentof the present invention, data
`packets whichare to be detected are transmitted by a second
`base station BS2 within GSM frames, and interruption
`phases for adjacent channel observation are inserted into the
`downlink data transmission from a UMTSbasestation BS1
`to a mobile station MS, with a period of 52 GSM frames
`lying between the start of a first interruption phase and a
`second interruption phase.
`In another variant embodiment, a period of 26 GSM
`frames lies betweenthestartof a first interruption phase and
`a second interruption phase.
`In another embodimentof the present invention, a period
`of nl GSM frameslies betweenthestart of a first interrup-
`tion phase and a second interruption phase, and a period of
`n2 GSM frameslies between the start of a second interrup-
`tion phase and a third interruption phase.
`In another embodimentof the present invention, a period
`of 6 GSM frameslies between thestart of a first interruption
`phase and a second interruption phase, and a period of 46
`GSM frames lies between the start of a second interruption
`phase and a third interruption phase.
`In another embodimentof the present invention, a period
`of 16 GSM frameslies betweenthe start of a first interrup-
`tion phase and a second interruption phase, and a period of
`36 GSM frames lies between the start of a second interrup-
`tion phase and a third interruption phase.
`By wayof example, while the mobile station MSis in the
`call condition or user data transmission condition with a
`
`current UMTSbasestation BS1, the interruption phases are
`inserted at particular points in time/intervals of time,
`between which there may be time spansof fixed or different
`length, into the downlink transmission, during which the
`reception device of the mobile station MS is switched to the
`reception of data packets from respective adjacent GSM
`base stations BS2, BS3. During the interruption phase 2, the
`UMTSbasestation thus interrupts the sending of data to the
`mobile station MS, and the mobile station MSinterrupts the
`reception and/or the processing of data sent by the UMTS
`
`10
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`15
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`25
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`base station BS1. The mobile station MS uses the reception
`device EE to carry out an adjacent channel search by virtue
`of the control device STE switching the reception device EE
`to the reception of adjacent GSM basestations BS2 and of
`the data packets sent
`thereby,
`in order to receive any
`synchronization data packets dp whicharrive, sent by adja-
`cent GSM base stations BS2, BS3.
`The aim of the adjacent channel search is also to detect a
`synchronization data packet which is to be detected. In one
`embodiment of the present invention, if, in one of these
`interruption phases, the mobile station MSreceives a syn-
`chronization data packet which is to be detected, then the
`adjacent channel search has ended, at least for this base
`station BS2, and the mobile station MS sends appropriate
`control information m (SCH-found) to the first base station
`BS1, the UMTSbasestation, possibly via suitable signaling
`channels. The UMTS base station BS1 then inserts no
`further interruption phases into the downlink data stream d,
`at least at first. In this case, the effective total duration of the
`interruption phases is generally shorter than the maximum
`effective total duration of the interruption phases.
`Asynchronization data packet whichisto be detected also
`can be detected using the reception of a characteristic
`frequency correction data packet, since the known frame
`structure after reception of a frequency correction data
`packet results in the position of a synchronization data
`packet to be known. Since, in the GSM system, the base
`stations BS2, BS3 transmit the frequency correction data
`packets one lime frame before the synchronization data
`packets, in one embodiment of the present invention, the
`mobile station MSis able not only to receive synchroniza-
`tion data packets but also to be switched to the reception of
`frequency correction data packets. In this case, the mobile
`station MS carries out an adjacent channel search in the
`interruption phases using the reception device EE, by virtue
`of the control device STE switching the reception device EE
`to the reception of adjacent GSM basestations BS2, in order
`to receive any synchronization data packets and frequency
`correction data packets which arrive, sent by adjacent GSM
`base stations BS2, BS3.
`Within the context of this application, the concept of “the
`mobile station being switched to the reception of data
`packets which are to be detected and/or characteristic data
`packets” is also understood as, after the customary analog
`and digital filtering, and possibly derotation, the received
`data packet being compared (e.g., correlated) with the cor-
`relation series corresponding to the training sequence of a
`characteristic data packet dp and/or with the correlation
`series corresponding to the training sequence of a data
`packet dp which is to be detected, and hence data packets
`which are to be detected and characteristic data packets are
`sought at the same timeorin parallel. Instead of correlation,
`other methods also may be used if appropriate (e.g., FIR,
`IRR orotherfilters). If a data packetis received or detected
`with sufficient quality, or the information transported using
`the data packetis ascertained with sufficient quality, etc., the
`reception result for this data packet can be said to be
`positive.
`In one embodiment, the mobile station MS is now able,
`after reception of a frequency correction data packet, to send
`information m to the UMTS base station BS1 (FCCH-
`found), which information now causes just one further
`interruption phase to be inserted into the sent data stream at
`first, in order to receive the synchronization data packet
`following the frequency correction data packet at a fixed
`distance. The knowledge about the relative positions in time
`of the frequency correction data packet and the synchroni-
`
`7
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`

`

`US 6,879,823 B1
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`10
`9
`frames lies betweena start of a first interruption phase and
`zation data packet allows the position in time and also the
`a start of a second interruption phase.
`duration (since the timeslot is now known) ofthe interrup-
`4. A method for data transmission in a mobile radio
`tion phase which is to be inserted to be matched to the
`system as claimed in claim 1, wherein a period of nl GSM
`position in time of the synchronization data packet which is
`frames lies betweena start of a first interruption phase and
`to be detected. Corresponding information about the posi-
`a start of a second interruption phase, and a period of n2
`tion in time of a frequency correction data packet or of a
`GSMframeslies betweenthestart of the second interruption
`following synchronization data packet can be transmitted
`phase andastart of a third interruption phase.
`with the FCCH-found message.
`5. A method for data transmission in a mobile radio
`the
`invention,
`In another embodiment of the present
`system as claimed in claim 4, wherein a period of 6 GSM
`mobile station is first switched to the observation of a first
`frames lies between the start of the first interruption phase
`and the start of the second interruption phase, and a period
`of 46 GSM frames lies between the start of the second
`interruption phase and the start of the third interruption
`phase.
`6. A method for data transmission in a mobile radio
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`15
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`adjacent GSM basestation BS2, after a su