United States Patent
`
`[19]
`
`[11] Patent Number:
`
`5,590,396
`
`Henry
`
`[45] Date of Patent:
`
`Dec. 31, 1996
`
`||||||l||||||||||||||||||||||l||I|||Il|l|||||||||||||||||||||l|l||||||H|||
`US005590396A
`
`..
`
`
`
`
`
`
`
`. 340/825.21
`5,010,330
`4/1991 Snowden etal.
`21:31 11
`. . ...
`,
`,
`y
`. ..... .
`..... 379/57
`5,054,052 10/1991 Nonarni ......
`21832382 12/133; §§.“i?i§“...:::::::1:::::1:::::::::::::::";;¢/EEETEZ
`5,101,510
`3/1992 Duckeck
`455/186
`5,123,933
`7/1992 Bows
`370/951
`5,140,698
`8/1992 Toko ..... . ..... .. .
`. .... 455/76
`5,150,361
`9/1992 Wieczorek et a1.
`.. 370/951
`5,175,874 12/1992 A ht
`..........
`455/89
`5,179,724
`1/1993 Lilrlfiiog .......
`..... 455/76
`518 4
`2/1
`3 W '
`al.
`......... ..
`. 340/825.44
`5,193,312
`3/1333 Gsgguitdsson etal. ................. 51/120
`IS;t<;te;1a1- -------------------------------
`6/1993 Fed
`-7-_-In 455/69
`6/1993 Harte ......
`..... 379/59
`7/1993 Sam et a1_ __
`_ 340/32544
`7/1993 Raith . . ....
`. .... .... 455/65
`7/1993 Nguyen ................................. .. 455/383
`(List continued on next page.)
`FOREIGN PATENT DOCUMENTS
`
`52201678
`5,224,152
`5,227,777
`5,230,077
`5,230,084
`
`[54] METHOD AND APPARATUS FOR A
`
`1751
`
`CELLULAR COMMUNICATION SYSTEM
`Inv«=m°r= Raymond 0- Hm Durham=N-C-
`_
`_
`_
`[73] Assignee: Ericsson Inc., Research Triangle Park,
`N.C.
`
`[211 APPL N°-‘ 2312000
`-
`[22] med‘
`Apr‘ 20’ 1994
`[51]
`Int. c1.° ....................................................... H04Q 7/22
`
`[52] U.S. C1.
`............
`455/33.1; 455/70; 455/343;
`_
`455/38-3
`[58] Field of Search .................................. 455/33.1, 38.3,
`455/541, 56.1, 343, 30; 379/59
`
`[56]
`
`References Cited
`U-3 PATENT DOCUMENTS
`
`0448789A2 ofoooo European M Ofl.__
`0514360” of 0000 European M Om .
`'
`
`Primapy Examiner._Edwafd Urban
`Anome), Agem, 0, F,-,,,,_Efic L gmsik
`
`[57]
`
`ABSTRACT
`
`A method and apparatus is provided for extending the
`battery life of a cellular radiotelephone. Acellular radiote1e—
`phone is conditioned to operate in a pager-only mode
`wherein the radiotelephone may ‘receive short messages
`from a base station while conserving battery 1ife_by cycli-
`cally adopting a deep-sleep state. The base station is notified
`by the radiotelephone before the radiotelephone enters the
`deep-sleep state that the radiotelephone is unable to receive
`messages. After a period of time, the radiotelephone wakes-
`up, re—estab1ishes contact with the base station and notifies
`the base station that the radiotelephone is ready to receive
`messages. After receipt of any messages the radiotelephone
`repeats the process.
`
`7 Clairris, 10 Drawing Sheets
`
`701
`
`
`
`Mobile swim Emars
`Pace-Onry Mada
`
`Mobtln Slalion ‘Walrus-Up‘
`
`Scan and Lock 10
`Comm! Channel
`
`Transmit a Power-Up
`negisuauon Mesage
`
`wan tar sus Mes!-I96: 6:
`Inaicauon maisus File Is Emply
`
`
`
`
`
`
`7n
`Mnhilfl Sutton Assumes
`Pacino am an by race»:
`and Listen: in SFACH
`(cw sus M
`712
`la
`Ion Pmmpts
`wl mam. Tone
`am necema Massage
`ls Displays-1 an Dtsolav
`
`7117
`Ynanslllfl -'1 Power-Down
`Hoasvmiion mange
`708
`Emu 'D9€P516flP Stats‘
`709
`Remain In 'De¢D5|6€p Sula‘
`Mode lo:a Proaeumunod
`Period :1! Tlme
`
`
`Ras1ano1d¢axBtock7DI
`
`
`
`
`
`1
`
`GOOGLE 1008
`
`4,577,315
`4,652,875
`4,691,382
`4,736,461
`4,745,408
`4.785.468
`4,794,649
`4,839,639
`4,852,148
`4,903,319
`4,903,335
`4,939,770
`4,955,080
`4,961,073
`4,964,121
`4,969,180
`4,977,611
`
`4,987,317
`4,995,099
`4,996,526
`5,001,471
`
`5/1984 Leslie etal. ........................... 455/38.3
`4,449,248
`4,479,125 10/1984 Mori ..........
`.. 340/825.44
`4,523,332
`6/1985 Mori ..... .. ...... .
`.... ... 455/343
`B31‘-011 €12
`..
`3/1986 Otsuka
`3/1987 Waki
`......
`9/1987 Nakajima ......
`4/1988 Kawasaki et al.
`5/1988-Nagata et a1.
`11/1988 Yoshida ...--
`12/1988 Fujiwara
`..
`6/1989 Sato et a1.
`7/1989 Shibata et al.
`2/1990 Kasai et a1.
`2/1990 Shimizu
`7/1990 Makino
`9/1990 Wagai et al.
`10/1990 Drapac et al.
`10/1990 Moore ............. ..
`11/1990 Watterson et a1.
`12/1990 Mani .................
`
`
`
`..
`
`.
`
`......... 370/95
`.. 340/825.44
`. .. .... 455/343
`455/343
`340/825.44
`.. ... 375/75
`455/343
`34°/gggjg
`455/33
`455/343
`379,61
`455/343
`__ 340/s25_44
`370/100.1
`379/58
`455/151
`......................... 307/40
`1/1991 Poumain et al.
`2/1991 Davis ...................................... 455/343
`2/1991 DeLuca ....... ..
`.. 340/825.44
`3/1991 Snowden et al.
`................ .. 340/825.21
`
`GOOGLE 1008
`
`1
`
`

`
`5,590,396
`Page 2
`
`U.S. PATENT DOCUMENTS
`
`5,265,270
`
`11/1993 Stengel et al.
`
`.......................... 455/343
`
`...................." 370/953
`8/1993 Natamjan at al.
`5241542
`5,251,325 10/1993 Davis et all
`'_ _ ' _ _'
`_ _ __ __ 455/383
`
`
`5,252,963
`10/1993 Snowden et a1_
`,_
`340/g25_44
`
`5,274,843
`5,301,225
`5,361,397
`
`............................ 455/383
`12/1993 Murai.eta1.
`........................... 455/343
`4/1994 Sulllkl et 31.
`11/1994 Wright
`.................................. .. 455/343
`
`2
`
`

`
`....._III:P_U_../__M_H,,0\—.__—Wm_.O_._IIIIIIIIIIIII|II.FOO—.
`I|IIIIIIIII|ll<_.O_.
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`u9_2_;m__/umcogzm_D_o__a:n___NZo__§n___.mow__mo..H3:m:m:HHm:m:2:H
`
`ll_w_o:m:m:HHm:8._9..__%_3__o:3_H»,HKH_KH_I__YA__o:_____52
`6IIIII|IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
`
` \S>HSH0m:o:ao_m._.V_HLm:o.._Qo_m._.-_3H2:o__8_>.H_Am__aos_mo.H8._%H0....HHo:_1,_vtozzmz__xséoz_MH.mEmOm:ocam_o._.__m:o.._am_o._.Hm_mmmmmmz
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`/</E.__mow_O_._._H\,r\HHE_m_e:.3.
`
`_tH
`
`3
`
`
`

`
`U.S. Patent
`
`Dec. 31, 1996
`
`Sheet 2 of 10
`
`5,590,396
`
`201
`
`Call Attempt to
`Mobile Station
`
`
`
`202
`
`Yes
`
`
`
`
`Does
`Mobile Station
`No
`
`
`Respond to
`Page ?
`
`204
`
`Connect Call in
`
`Usual Manner
`
`203
`
`Call is Directed
`
`to Message Center
`
`205
`
`Caller is Prompted
`
`to Enter Short
`
`
`Alphanumeric Message
`
`
`
`
`
`
`FIG. 2A
`
`206
`
`
`
`Message is Entered
`and Delivered to
`
`A System Message Center
`
`
`
`
`207
`
`4
`
`

`
`U.S. Patent
`
`Dec. 31, 1996
`
`Sheet 3 of 10
`
`5,590,396
`
`207
`
`A
`
`209
`
`Mobile Station
`
`Registers with System
`
`FIG. 2B
`
`Yes
`
`210
`
`
`Mobile Station
`‘n Home System
`
`
`
`
`No
`
`212
`
`211
`
`Message Center
`
`Delivers Messages
`
`Center Transfers
`
`Messages to Roam System
`
`MTSO via lS—41 Link
`
`
`
`
`214
`
`Messages Delivered to
`Mobile Station Accord-
`
`in to DCC Protocols
`
`
`
`Registration Message is
`Sent to MobiIe’s Home
`
`System via IS-41 Interface
`
`
`21 3
`
`
`
`to MTSO Home System Message
`
`
`
`5
`
`

`
`U.S. Patent
`
`Dec. 31, 1996
`
`Sheet 4 of 10
`
`5,590,396
`
`109
`
`/
`
`303
`
`305
`
`306
`
`
`
` Generator !
`
`
`
`
`
`
`
`
`Anamg
`Encode
`
`-
`
`Modulator
`
`Transmitter
`
`308
`
`‘
`
`309
`
`:
`
`6
`
`

`
`U.S. Patent
`
`Dec. 31, 1996
`
`Sheet 5 of 10
`
`5,590,396
`
`FIG. 4A
`
`PRIOR ART
`
`DCC
`
`Q
`
`Uplink
`iii
`
`Downlink
`51.5
`
`413
`
`407
`
`416
`
`RACH
`
`SPACH
`
`BCCH
`
`SCF
`
`RESERVED
`
`410
`
`.
`
`PCH
`
`F—BCCH
`
`41 1
`
`412
`
`ARCH
`
`E-BCCH
`
`SMSCH
`
`S-BCCH
`
`404
`
`405
`
`406
`
`7
`
`

`
`U.S. Patent
`
`Dec. 31, 1996
`
`Sheet 6 of 10
`
`5,590,396
`
`5».wownowAe
`
`Be8mow
`
`
`
`wEm.tma:w000
`
`am
`
`
`
`oEmEma>I000
`
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`
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`
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`
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`
`
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`
`8
`
`
`
`
`

`
`U.S. Patent
`
`Dec. 31, 1996
`
`Sheet 7 of 10
`
`5,590,396
`
`FIG. 5
`
`501
`
`
`
`Mobile Station
`
`is Powered-Up
`
`502
`
`Mobile Station Scans
`
`Control Channels and Locks
`
`
`its Receiver to a DCC
`and SPACH
`
`
`FIG. 6A
`
`601
`
`Mobile Station
`
`is Powered-Up
`
` User Presses
`
`602
`
`
`
`Function (FCN) Key
`
`on Keypad
`
`603
`
`User Presses Key 1
`
`and then Key 5
`
`604 "PAGE ONLY ON/OFF"
`
`is Displayed for
`5 Seconds on Display
`
`
`
`
` Mobile Station
`
`Enters/Exits
`Page-Only Mode
`
`
`
`
`
`
`Mobile Station Decodes
`
`
`FBCCH, EBCCH, SBCCH,
`
`
`
`504
`
`Mobile Station Transmits
`
`Power-Up Registration
`
`.
`
`505
`
`Mobile Station Assumes
`
`Paging Class Set in FBCCH
`
`
`
`
`Class and Listens for
`
`Pages/SMS Messages
`
`Mobile Station "Wakes-Up"
`During SPACH Slot Based
`on its Assigned Paging
`
`9
`
`

`
`U.S. Patent
`
`Dec. 31, 1996
`
`Sheet 8 of 10
`
`5,590,396
`
`FIG. 6B
`
`109
`\
`
`607
`
`608
`
`UUDU
`
`FCN
`
`606
`
`610
`
`BB7
`G3
`[DE
`%
`
`10
`
`

`
`U.S. Patent
`
`Dec. 31, 1996
`
`Sheet 9 of 10
`
`5,590,396
`
`FIG. 7
`
`Mobile Station Enters
`
`Page-Only Mode
`
`701
`/
`
`702
`/
`
`Mobile Station "Wakes-Up"
`
`Scan and Lock to
`
`_
`
`Control Channel
`
`Transmit a Power—Up
`Registration Message
`
`703
`
`704
`
`705
`
`.
`
`Wait for SMS Messages or
`indication that SMS File is Empty
`
`706
`
`SMS Messages
`
`711
`
`Mobile Station Assumes
`
`Paging Class Set by F BCCH
`and Listens to SPACH
`
`Received ?
` 707
`for SMS Messages
`712 Enter "Deep-Sleep State"
`
`
`Remain in "Deep-Sleep State"
`
`
`
`
`Mobile ‘Station Prompts
`User with Audible Tone
`
`
`
`is Displayed on Display
`
`and Received Message
`
`\
`
`Transmit a Power-Down
`
`Registration Message
`
`
`
`708
`
`709
`\
`
`
`
`Mode for a Predetermined
`
`Period of Time
`
`710
`
`Restart Cycle at Block 701
`
`11
`
`11
`
`

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`

`
`1
`METHOD AND APPARATUS FOR A
`DEEP-SLEEP MODE IN A DIGITAL
`CELLULAR COMMUNICATION SYSTEM
`
`FIELD OF THE INVENTION
`
`The present invention relates generally to cellular radio
`communications and, more specifically, to a method and
`apparatus for maximizing the battery life of portable cellular
`radiotelephones used in digital cellular communication sys-
`tems.
`
`BACKGROUND OF THE INVENTION
`
`Cellular communications systems are well-known. Ana-
`log cellular systems such as designated AMPS, ETACS,
`NET—450, and NET-900 have been deployed successfully
`throughout the world. More recently, digital cellular systems
`such as designated IS-54B in North America and the pan-
`European GSM system have been introduced. These sys-
`tems, and others, are described, for example, in the book
`titled Cellular Radio Systems by Balston, et al., published by
`Artech House, Norwood, Mass., 1993.
`
`The IS-54B specification entitled Cellular System Dual-
`Mode Mobile Station Base Station Compatibility Standard
`(available from the Telecommunications Industry Associa-
`tion, 2001 Pennsylvania Avenue, N.W., Washington , D.C.,
`20006) provides increased system capacity through digital
`time division multiple access (TDMA) while allowing com-
`patibility with existing analog systems. Mobile stations
`designed to meet the IS-54B specification are able to func-
`tion with both the new TDMA systems and the existing
`AMPS analog systems. Throughout this specification the
`terms mobile station, cellular telephone, cellular phone,
`mobile phone, and cellular radiotelephone are used inter-
`changeably to refer to the same device. One drawback to the
`current specification is that the both the digital and analog
`systems make use of the existing AMPS analog control
`charmels. Therefore TDMA capable mobile stations are
`constrained by the old analog protocols and are not able to
`fully utilize all the features possible with digital communi-
`cations.
`
`Currently, cellular mobile radiotelephones are limited in
`stand-by battery life because they must continuously moni-
`tor the analog control channel for paging messages indicat-
`ing an incoming call. Even with high capacity batteries,
`stand-by times in excess of about 24 hours are rare. This may
`be contrasted with paging receivers, or “beepers”, which
`have battery lives of about 100-200 hours from a single AA
`battery achieved by cyclical operation. The need for longer
`battery life in cellular radiotelephones is therefore self-
`evident.
`
`A digital control charmel (DCC) has recently been pro-
`posed to the Telecommunications Industry Association
`(TIA). The DCC specification is identified as PN 3011-1 and
`PN 3011-2 and is available from the TIA at the above
`
`address. When adopted, the DCC will become part of a new
`IS-54C specification. The specifications PN 3011-1 and PN
`3011-2 are incorporated herein by reference in their entirety.
`One feature of the DCC is called short message service
`(SMS.) With SMS it will be possible to send alphanumeric
`messages to compatible mobile stations in a manner similar
`to that presently done with paging receivers. This feature
`opens the door for many new cellular phone options.
`Unlike voice communications in which a caller is waiting
`for a response from the called-party, alphanumeric messages
`do not require an immediate response and can be stored and
`
`5,590,396
`
`2
`
`subsequently delivered to the mobile station some period of
`time after origination. This allows the mobile phone to adopt
`what will hereinafter be referred to as a “pager-only mode”
`of operation.
`The pager-only mode of the mobile station will allow the
`user to receive SMS messages but not to receive incoming
`conversation type calls. The call origination capability
`remains thereby allowing the user to place calls without
`exiting the pager-only mode. The pager-only mode offers
`many advantages to the user not the least of which is the
`benefit of much longer battery life. The pager-only mode
`also functions as a do-not-disturb mode for business meet-
`ings, and allows the mobile station user to perform “call
`screening” of incoming calls. Unlike the known broadcast
`page receiver (i.e., “beeper”) , the mobile phone is imme-
`diately available to place a call to the message originator.
`
`SUMMARY OF THE INVENTION
`
`In view of the foregoing background, it is therefore an
`object of the present invention to provide a method for
`increasing the battery life of a battery-powered cellular
`radiotelephone.
`It is also an object of the present invention to provide a
`pager-only mode for a cellular radiotelephone thereby
`allowing the user of a portable cellular radiotelephone to
`receive short messages broadcast to it from a cellular base
`station.
`
`These and other objects, advantages, and features of the
`present invention. are provided by a method for saving
`battery power in a cellular radio communication system
`having a base station with a base station control signal and
`a mobile station conditioned to adopt a pager-only mode
`wherein the mobile station cyclically transmits a first signal
`to the base station indicating that the mobile station is unable
`to receive messages from the base station. After transmitting
`the first signal, the mobile station is further conditioned to
`deactivate ‘selected circuits within itself for a predetermined
`period of time and then to automatically reactivate the
`selected circuits after the predetermined time period has
`elapsed and to transmit a second signal to the base station
`indicating that the mobile station is able to receive messages.
`In another embodiment,
`the first and second signals
`transmitted by the mobile station include power-down and
`power-up registration messages.
`In yet another embodiment, the mobile station is adapted
`to allow the user to set and reset the pager-only mode.
`A further embodiment of the invention comprises a cel-
`lular communications system having a mobile station con-
`ditioned to transmit a first signal to a base station to notify
`the base station when the mobile station is unable to receive -
`messages. The mobile station includes a controller to deac-
`tivate selected circuits within the mobile station for a period
`of time and to automatically re-activate the selected circuits
`after the period of time has expired. The mobile station is
`further conditioned to transmit a second signal after the
`period of time has elapsed to notify the base station that the
`mobile station is ready to receive messages. The mobile
`station is conditioned to repeat this sequence of operations
`until it is set by the user into another mode. The controller
`is adapted to cause other selected circuits, not deactivated, to
`operated at reduced levels of power consupmption to further
`increase battery life. The predetermined period of time may
`be adjusted to even further increase battery life.
`In accordance with the present invention, a method for
`saving battery power in a cellular radio communication
`
`20
`
`25
`
`30
`
`35
`
`50
`
`55
`
`60
`
`13
`
`13
`
`

`
`3
`
`4
`
`5,590,396
`
`system having a base station with a base station control
`signal, by transmitting a first signal from a mobile station to
`the base station indicating that the mobile station is unable
`to receive messages from the base station, deactivating
`selected circuits within the mobile station for a predeter-
`mined period of time, automatically reactivating said
`selected circuits within the mobile station after said prede-
`termined time period, transmitting a second signal from the
`mobile station to the base station indicating that the mobile
`station is able to receive messages.
`These and other features and advantages of the present
`invention will be readily apparent to one of ordinary skill in
`the art from the following written description when read in
`conjunction with the drawings in which like reference
`numerals refer to like elements.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a schematic illustration of two interconnectable
`cellular systems;
`FIG. 2A is a flowchart illustrating how SMS messages are
`entered into the cellular system;
`FIG. 2B is a flowchart illustrating how SMS messages are
`delivered a mobile station;
`FIG. 3 is a partial schematic block diagram of a mobile
`station illustrating those elements relevant to the present
`invention;
`
`FIG. 4A is a schematic illustration of the uplink and
`downlink DCC;
`FIG. 4B is a schematic illustration of the downlink DCC
`frame structure;
`
`FIG. 5 is a flowchart illustrating the method used by the
`mobile station to monitor the DCC;
`
`FIG. 6A is a flowchart illustrating the method used to
`place the mobile station into a pager-only mode;
`FIG. 6B is an illustration of an exemplary cellular radio-
`telephone showing the keys required to place the mobile
`station into the pager-only mode;
`FIG. 7 is a flowchart illustrating the operation of the
`mobile station operating in a pager-only mode;
`FIG. 8 is a timing diagram illustrating the operation of the
`mobile station operating in a pager-only mode.
`
`DESCRIPTION OF THE INVENTION
`
`In the following description, for purposes of explanation
`and not limitation, specific details are set forth, such as
`particular circuits, circuit components, techniques, etc. in
`order to provide a thorough understanding of the invention.
`However it will be apparent to one of ordinary skill in the art
`that the present invention may be practiced in other embodi-
`ments that depart from these specific details. In other
`instances, detailed descriptions of well-known methods,
`devices, and circuits are omitted so as not to obscure the
`description of the present invention with unnecessary detail.
`System Operation
`Referring initially to FIG. 1, a typical cellular network
`100 is illustrated showing the interconnection of two
`regional systems 101A and 101B. The system components
`shown are exemplary and as is obvious to one of ordinary
`skill in the art not all cellular systems will be limited to, or
`inclusive of,
`these components; other arrangements are
`possible as well. Regional system 101A comprises, for
`example, a mobile telephone switching oflice (MTSO) 107
`connected to a plurality of base stations 110 each by com-
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`munications link 113. Base station 110 provides the radio
`link 114 to each mobile station 109. Landline telephone user
`103 and data users 102 are connected to the public telephone
`switched network (PSTN) 105 by communications link 115.
`The PSTN is,
`in turn, connected to the MTSO 107 by
`communications link 116. MTSO 107 is also connected to a
`visiting/home location register (VLR/HLR) 106 and to mes-
`sage center 104. Interconnection between networks 101A
`and 101B are effected between MTSOs 107 via an IS-41
`communications link, in this case microwave link 108 using
`microwave antennas 108A and 108B, or alternately through
`the long-distance PSTN lines 117. As shown, communica-
`tion connections may be established between landline tele-
`phone user 103 or data users 102 and mobile stations 109.
`When the complete connection occurs within the boundaries
`101A or 101B mobile station 109 is said to be in its “home”
`system. If a connection occurs across systems 101A and
`101B mobile station 109 is said to be “roaming.” The terms
`“home system” and “roaming” are well-known to one of
`ordinary skill in the art.
`As shown in FIG. 1 connections may occur between
`mobile stations 109 in the same system or mobile stations in
`different systems. Similarly, a communications connection
`may occur between a landline telephone user 103 or data
`user 102 and a mobile station 109. It may further be stated
`that mobile station 109 may be a cellular radiotelephone, a
`radio modem, or a personal digital assistant (PDA.)
`The typical operation of the SMS procedure is described
`by the flowchart of FIG. 2A. In one instance, for example,
`a landline telephone user, or caller, 103 attempts to place a
`call through the PSTN 105 and the MTSO 107 to mobile
`station 109 as indicated in block 201. If mobile station 109
`answers (i.e., responds to the page broadcast from one of the
`base stations 110) then the connection is made according to
`known methods as indicated by block 203. Alternatively, if
`mobile station 109 does not answer then the caller 103 is
`routed through the MTSO 107 to the message center 104 as
`indicated in block 204.
`
`There are several ways in which a message in block 206
`may be received by the message center 104. The prompt in
`block 205 may, in one instance, be a human operator who
`answers the call and enters the message through a computer
`or console into message center 104. In another instance, the
`user 103 is prompted as indicated in block 205 to enter the
`message via the telephone keypad in a manner similar to the
`known procedures used to leave a message to be transmitted
`to a broadcast paging receiver. In yet another instance, the
`user may directly transfer the message from a personal
`digital assistant, or a personal computer 102. In this case the
`prompt in block 205 is a computer tone similar to a fax
`machine’s set-up signaling. Regardless of the method used,
`a brief alphanumeric message is stored in message center
`104 for later transmission to mobile station 109.
`
`A description of how the stored message is forwarded to
`mobile station 109 is shown by the flowchart of FIG. 2B.
`When the mobile station is first powered-on, or otherwise
`wishes to make contact with the system as will be described
`in more detail hereinafter, mobile station 109 performs a
`registration with the system according to Section 6.3.7 of
`Specification PN 3011-l as indicated in block 209. Based on
`information contained within mobile station’s registration
`signal, system 101A, for example, determines if mobile
`station 109 is in its home system 101A or if it is roaming in
`system 101B as indicated in block 210. If the mobile station
`is in home system 101A, the SMS message stored in the
`message center 104 is broadcast as indicated in block 214 to
`mobile station 109 via the DCC protocols to be described. If,
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`alternately, mobile station 109 is roaming in, for example,
`system 101B a registration message is sent to mobile sta-
`tion’s 109 home system 101A via the IS-41 link 108 as
`indicated in block 212. Upon receipt of the registration
`message, the home system 101A message center 104 trans-
`fers the SMS message previously stored to roaming system
`101B via the IS-41 link 108 as indicated in block 213. If no
`SMS messages are stored an indication thereof is alternately
`communicated. Once received,
`the SMS messages are
`broadcast via base station 110 to mobile station 109 accord-
`ing to the DCC specification.
`Description of the DCC
`A complete and thorough description’ of the DCC is
`provided in specifications PN 3011-1 and PN 3011-2 pre-
`viously incorporated by reference. In the following, a sum-
`mary description of the DCC is provided as necessary to
`make clear the operation of the present invention.
`The DCC 420 comprises the logical channels shown in
`FIG. 4A which is adapted from FIG. 2-3 of Specification
`301 1- 1. Uplink channel 414 transmitted from mobile station
`109 to base station 110 consists of the random access
`channel (RACH) 413. Downlink channel 415 transmitted
`from base station 110 to mobile station 109 consists of the
`broadcast control channel (BCCH) 416 and the short mes-
`sage, paging, and access control charmel (SPACH) 407.
`In FIG. 4B is shown the frame structure of the Downlink
`DCC 415 as specified in specification PN 3011-1. To ensure
`compatibility with existing equipment, the DCC makes use
`of the present IS-54B TDMA frame structure. A TDMA
`frame 400 is defined as three contiguous time slots 401, 402,
`and 403. As specified in IS-54B, mobile station 109 will
`receive signals broadcast from base station 110 on every
`specified third slot, for example, mobile station 109 may
`continuously monitor slot 1 401 and slot 4 401A, slot 2 402
`and slot 5 402A, or alternately slot 3 403 and slot 6 403A.
`Therefore during each TDMA frame 400 the mobile station
`receiver 303 (FIG. 3) to be described in more detail here-
`inafter need only be on ‘/3 of the time.
`A DCC superframe 408 is defined as a number of sequen-
`tial TDMA frames 400. In the example shown in FIG. 4B,
`the DCC superframe 408 comprises information transmitted
`sequentially on every third slot of an IS—54B frame. Within
`the DCC superframe 408 are contained dilferent information
`slots. The FBCCH 404, EBCCH, 405 and the SBBCH 406
`are broadcast control channels which transmit global infor-
`mation for all mobile stations. FBCCH 404, EBCCH 405,
`and SBCCH 406 may extend over several slots as indicated
`by the dots in adjacent slots of the DCC superframe 408. The
`FBCCH 404, EBCCH 405, and the SBCCH 406 are
`described in more detail in Section 2.3.2 of PN 3011-1.
`
`Slot 407 contains information directed at specific mobile
`stations 109 comprising the paging control channel (PCH)
`410, access control channel (ARCH) 411, and the short
`message service control charmel (SMSCH) 412.
`Two DCC superframes 408 are arranged sequentially into
`a primary and secondary superframe which together are
`known as a hyperframe 409. SMS messages may be inter-
`leaved in the SPACH slot 407 across several hyperframes.
`Mobile Station Operation
`Normal monitoring of the DCC downlink 415 by mobile
`station 109 involves checking, for example, each SPACH
`slot 407 on the DCC superframe 408 as shown in FIG. 4B.
`In order to monitor each slot, the mobile station executes the
`sequence of operations shown by the flowchart of FIG. 5.
`Mobile station 109 first “powers-up” as indicated in block
`501. Powering up may be effected by the user turning mobile
`
`station 109 on from being completely off, or it may be
`waking up from what is refered to as a “deep sleep state” as
`will be described in more detail hereinafter. After powering
`up, mobile station 109 scans, according to known methods,
`a predetermined set of DCC downlink charmels 415 and
`locks its receiver to one of the DCCs 415 as indicated in
`block 502. Once locked to a DCC 415, mobile station 109
`receives and decodes DCC hyperframe 409 as indicated in
`block 503. In the FBCCH slot 404 is contained information
`identifying the SPACH paging slot and the paging class
`mark, to be described in more detail hereinafter, to be used
`by mobile station 109. As indicated by block 504, mobile
`station 109 transmits via RACH 414 a “power-up” registra-
`tion to the base station 110 and receives via the downlink
`DCC 415 an acknowledgment back from base station 110.
`The acknowledgment may contain additional information
`instructing mobile station 109 to monitor another DCC 420
`or to otherwise override the FBCCH information. Assuming
`that an acknowledgment and no instructions are received
`from base station 110, mobile station 109 assumes in block
`505 the paging class corresponding to the paging class mark
`in FBCCH slot 404 received in block 503. Paging class
`marks are described in greater detail in section 4.5.5 of
`specification PN 3011-1.
`There are 8 paging classes designated 1—8 which specify
`the frequency with which mobile station 109 listens to
`SPACH slot 407 for a SMS message as indicated in block
`506. A first mobile station 109 assigned to paging class 1
`monitors one SPACH slot 407 for each hyperframe 409, a
`second mobile station 109 assigned to paging class 2 moni-
`tors one SPACH slot 407 for every other hyperframe 409, a
`third mobile station 109 assigned to paging class 3 monitors
`one SPACH slot 407 for every third hyperframe 409, and so
`on. In paging class 8, for example, mobile station 109 may
`only monitor a SPACH slot 407 every 2 minutes for SMS
`messages. This procedure allows the system operator to
`assign so called sleep-modes. This procedure is known and
`described in greater detail in specifications PN 3011-1 and
`PN 3011-2.
`
`Referring now to FIG. 3, a partial functional block
`diagram of a mobile station 109 is shown. During SPACH
`slot 407, power must be applied to receiver 303, demodu-
`lator 302, controller 304, timing generator 305, and the
`timebase/automatic frequency control (AFC) 306. The time-
`base 306 may be a temperature controlled crystal oscillator
`(TCXO). In between SPACH slots 407 however, all that is
`required to be activated is timing generator 305 and the
`timebase/AFC 306 to keep track of when the next SPACH
`slot 407 is to occur. However, if the next SPACH slot 407 is
`to be decoded correctly, as is obvious to one of ordinary skill
`in the art, the timing accuracy must be accurate to within a
`couple of symbol periods. This requires timing generator
`305 and the timebase/AFC 306 to operate in a precise
`manner wherein power must also be applied to the controller
`304 to control operation of timing generator 305 and AFC
`306. During the intervals between SPACH slots 407 timing
`generator 305 and controller 304 may operate at a greatly
`reduced instruction rate and therefore have reduced current
`
`requirements. However, in order to maintain the timing
`accuracy required the timebase/AFC 306 must remain fully
`active between SPACH slots 407. The necessity of main-
`taining the timebase/AFC 306 fully active places a lower
`limit on the amount of current drawn from battery 310 and
`hence limits the absolute battery life.
`Operation of the Page Only Mode
`When a user of mobile station 109 wishes to place calls
`but not to receive incoming calls the user may simply turn
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`the phone 013' until such time as the user decides to place a
`call. By so doing the user may maximize the life of battery
`310 since little or no current is drawn by the circuits shown
`in FIG. 3 when mobile station 109 is deactivated. However,
`if the mobile station 109 is deactivated mobile station 109 is
`not able to receive incoming SMS messages.
`If, alternately, the user of mobile station 109 wishes to
`place calls and to also receive SMS messages while at the
`same time maximizing battery life, the user of mobile station
`109 may select to place the phone into what is refered to as
`the “pager-only mode.” One method by which the user may
`place mobile station 109 into a pager-only mode is described
`in FIG. 6A. It will be understood by those of ordinary skill
`in the art that there are many ways for the user to establish/
`select a pager-only function in a cellular telephone. The
`example given in FIGS. 6A and 6B are therefore exemplary
`only and are not meant to be lirnitative. First, as indicated in
`block 601, the mobile station 109 is be turned on in the
`normal manner. Then as shown in FIG. 6B ,the user then
`sequentially presses function key 607, the ‘l’ key 608, and
`finally the ‘5’ key 609 on the keypad of mobile station 109
`as indicated in blocks 602-603. Executing this sequence will
`toggle the mobile station into the pager-only mode. Repeat-
`ing the sequence will reset the mobile station into the normal
`stand-by mode where mobile station 109 monitors the DCC
`according to its assigned paging class. Another method for
`placing mobile station 109 into a pager-only mode requires
`the user to enter a menu mode and, using the arrow keys 610
`commonly found on mobile stations, the user can sequence
`through the available options to select or deselect
`the
`pager-only mode. To confirm that mobile station 109 is in
`the pager-only mode a brief indication will be shown on
`display 606 of the mobile station 109 as indicated in block
`604. After a brief period, display 606 will go blank until such
`time as a SMS message is received.
`Referring now to FIG. 7, the operation of mobile station
`109 in the pager-only mode is described. Once mobile
`station 109 has entered the pager-only mode as indicated in
`block 701 all circuits non-essential to the operation of the
`mobile station 109 while in the pager-only mode are de-
`activated as will be described. This is refered to as the
`
`“deep-sleep” state. Referring back to FIG. 3, in th