Umted States Patent [191
`Ayerst et al.
`
`US005644568A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,644,568
`Jul. 1, 1997
`
`[54] METHOD AND APPARATUS FOR
`ORGANIZING AND RECOVERING
`INFORMATION COMNIUNICATED IN A
`
`RADIO COMMUNICATION SYSTEM
`
`4,519,068
`4,755,816
`4,860,003
`5,128,665
`5,282,205
`
`5/1985 Krebs et a1. ............................ .. 370/82
`7/1988 DeLuca .......... ..
`8/1989 DeLuca et a1. .................. .. 340/825.52
`7/1992 DeLnca et a1. .
`1,1994 Kuznicki _
`
`[75] Inventors: Douglas Irvin Ayerst, Delray Beach;
`Millik J - Khan, Boynton Beach;
`Michael James Rudowicz, Delray
`Beach, all of Fla.
`
`5/1994 Kuzmck‘ et a1‘ ‘
`5’311’516
`Primary Examiner—Wellington Chin
`Assistant Examiner—-Huy D. Vu
`Attomey, Agent, or Finn-James A. Lamb
`
`[73] Assignee: Motorola, Inc., Schaumburg, 111.
`
`[21] APPL N05 404,698
`[22] Filed:
`Man 15 1995
`’
`[51] Int. Cl.6 ...................................................... .. H04J 3/26
`[52] US. Cl. ................... .. 370/311; 340/825.47; 455/343;
`370/312; 370/432; 370/468; 370/471; 370/522
`[58] Field of Search ................................ .. 370/83, 82, 92,
`370/93, 94.1, 99, 110.1, 110.4, 13, 17;
`340/825.47, 825.48, 825.52, 825.53, 825.44;
`455/343
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`ABSTRACT
`[57]
`A system controller (102) generates and transmits a radio
`signal having long messages in data frames (370), and short
`and long messages in control frames (360). A set of selective
`call radio addresses is included at the beginning of a control
`frame (360), each selective call radio address including a
`subvector Which indicates the starting position of a short
`message or a vector packet Within the control ?ame (360).
`Vector packets indicate Starting positions of long messages
`within the control frame (360), within other control frames
`(360), and within data frames (370) A selective call radio
`(106) receives the radio signal and recovers and processes
`the short and long messages, using the snbvectors and
`vectors to idenlify the positions of the short and long
`messages‘
`
`4,427,980
`
`l/1984 Fennell et a1. ................... .. 340l825.52
`
`6 Claims, 9 Drawing Sheets
`
`4
`[331 [332 K333
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`
`10
`
`General Electric Co. 1008 - Page 1
`
`

`
`US. Patent
`
`Jul. 1, 1997
`
`Sheet 1 0f 9
`
`5,644,568
`
`9/
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`General Electric Co. 1008 - Page 2
`
`

`
`US. Patent
`
`Jul. 1,
`
`1997
`
`Sheet 2 0f 9
`
`5,644,568
`
`t
`00
`
`116
`
`202
`f
`
`204 [
`
`CELL SITE
`CONTROLLER
`
`MESSAGE
`HANDLER
`
`[- 206
`
`0
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`0
`INTERFACE
`4-»
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`110
`4+
`0
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`
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`
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`DATA BASE
`
`208
`f.
`OUTBOUND
`MESSAGE
`MEMORY
`
`W12 I
`
`I
`
`210 f
`CHANNEL
`ASSIGNMENT
`ELEMENT
`
`I
`
`I
`
`DATA FRAME
`ELEMENT
`
`216
`
`ADDRESS
`FIELD
`ELEMENT
`
`214 r
`INFORMATION
`FIELD
`ELEMENT
`
`‘I
`
`218
`
`I
`I
`
`CONTROL '
`FRAME
`ELEMENT
`
`102
`FIG. 2 —
`
`General Electric Co. 1008 - Page 3
`
`

`
`US. Patent
`
`Jul. 1, 1997
`
`Sheet 3 of 9
`
`5,644,568
`
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`CYCLE O CYCLE 1 CYCLE 2 g
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`
`General Electric Co. 1008 - Page 4
`
`

`
`U.S. Patent
`
`Jul. 1, 1997
`
`Sheet 4 of 9
`
`5,644,568
`
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`General Electric Co. 1008 - Page 5
`
`

`
`US. Patent
`
`Jul. 1, 1997
`
`Sheet 5 of 9
`
`5,644,568
`
`FIG. 5
`
`524 \.
`
`33 1 332 525
`
`General Electric Co. 1008 - Page 6
`
`

`
`U.S. Patent
`
`Jul. 1, 1997
`
`Sheet 6 of 9
`
`5,644,568
`
`mmIO._._>>m
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`
`General Electric Co. 1008 - Page 7
`
`

`
`US. Patent
`
`Jul. 1, 1997
`
`Sheet 7 0f 9
`
`5,644,568
`
`710
`
`INPUT MESSAGE TO RADIO
`COMMUNICATION SYSTEM
`USING THE PSTN.
`720
`I
`MAP PSTN NUMBER TO /
`SELECTIVE CALL RADIO ADDRESS
`
`I
`IDENTIFY A CHANNEL
`ASSIGNMENT
`
`730
`_/
`
`I
`
`DETERMINE NEXT CONTROL FRAME 740
`DECODED BY THE SELECTIVE CALL /
`RADIO BASED ON SYSTEM
`MANAGEMENT INFORMATION
`
`SHORT
`MESSAGE
`
`MESSAGE
`TYPE?
`
`750 LONG
`MESSAGE
`
`/- 780
`ASSEMBLE SHORT MESSAGE PACKET
`IN INFORMATION FIELD OF THE
`CONTROL FRAME WHERE SELECTIVE
`CALL RADIO IS ADDRESSED
`
`f 760
`GENERATE LONG
`MESSAGE 'N
`A CONTROL OR DATA
`FRAME
`
`GENERATE SELECTIVE CALL RADIO
`ADDRESS IN THE ADDRESS FIELD
`OF THE CONTROL FRAME. INCLUDE
`POSITION OF DATA PACKET AS A
`SUBVECTOR IN THE ADDRESS
`
`f 795
`TRANSFER FORMATTED CONTROL
`AND DATA FRAMES TO CELL SITE
`CONTROLLER FOR TRANSMISSION
`
`I
`* 770
`ASSEMBLE VECTOR PACKET
`IN INFORMATION FIELD OF THE
`CONTROL FRAME wHEREIN THE
`SELECTIVE CALL RADIO IS
`ADDRESSED. INCLUDE
`PROTOCOL POSITION
`AND CHANNEL SELECTED IN
`THIS VECTOR PACKET.
`I
`
`FIG 7
`-
`
`General Electric Co. 1008 - Page 8
`
`

`
`US. Patent
`
`Jul. 1, 1997
`
`Sheet 8 of 9
`
`5,644,568
`
`SWITCH TO NORMAL POWER ,805
`MODE AT BEGINNING OF
`PREDETERMINED CONTROL FRAME
`810
`I
`‘J
`SYNC TO FORWARD CHANNEL
`FRAME SYNCHRONIZATION PATTERN
`
`815
`+
`RECEIVER BLOCK INFORMATION WORDS J
`OF FORWARD CHANNEL TRANSMISSION
`820
`T
`DECODE BLOCK INFORMATION WORDS J
`TO DETERMINE START OF ADRESS
`FIELD AND ADDRESS BOUNDARY
`825
`+
`PERFORM COMPARISON BE'IWEEN J
`ADDRESS DECODED AND STORED
`ADDRESSES OF SELECTIVE CALL RADIO
`
`830
`
`MATCH
`FOUND?
`
`MORE
`ADDRESSES?
`
`840
`/
`DETERMINE SUBVECTOR EMBEDDED IN
`THE ADDRESS WORDS AND DECODE
`POSITION OF DATA PACKET ASSOCIATED
`WITH THE SELECTIVE CALL RADIO ADDRESS
`
`a37\
`
`SWITCH TO LOW
`POWER MODE
`
`FIG. 8
`
`General Electric Co. 1008 - Page 9
`
`

`
`US. Patent
`
`Jul. 1, 1997
`
`Sheet 9 of 9
`
`5,644,568
`
`SWITCH TO LOW POWER MODE
`
`845
`./
`
`I
`SWITCH TO NORMAL POWER MODE 350
`BEFORE THE BEGINNING OF
`THE DATA PACKET
`
`RECOVER THE DATA
`PACKET
`
`/855
`
`860
`VECTOR x DATA
`PACKET
`PACKET
`TYPE?
`
`sHORT MESSAGE
`PACKET
`
`890 \
`PROCEss SHORT MESSAGE
`IN THE CONTROL FRAME ON
`THE SAME CHANNEL WHERE
`ADDRESS WAS DECODED
`
`I f. 895
`SWITCH To LOW
`POWER MODE
`
`DECODE PROTOCOL 865
`Lgisguggsaglz ’
`
`+ r 870
`
`SWITCH TO LOW
`POWER MODE
`f 875
`I
`SWITCH TO NORMAL POWER
`MODE BEFORE THE BEGINNING
`OF THE LONG MESSAGE
`f 880
`+
`PROCESS LONG MESSAGE IN
`THE CONTROL OR DATA FRAMES
`IN THE CYCLE ON ANY ONE OF
`THE CHANNELS OPERATING
`IN THE RADIO SYSTEM
`I
`['885
`SWITCH TO LOW
`POWER MODE
`
`FIG. 9
`
`General Electric Co. 1008 - Page 10
`
`

`
`5,644,568
`
`1
`METHOD AND APPARATUS FOR
`ORGANIZING AND RECOVERING
`INFORMATION COMMUNICATED IN A
`RADIO COMlVIUNICATION SYSTEM
`
`FIELD OF THE INVENTION
`
`This invention relates in general to a method and appa
`ratus for organizing and recovering information communi
`cated in a radio signal, and in particular to an improved
`technique for identifying a position of a message in a radio
`signal, in which the message is included in a radio signal
`transmitted on a different radio channel than a radio signal
`which includes the address of the selective call radio for
`which the message is intended.
`
`10
`
`BACKGROUND OF THE INVENTION
`
`25
`
`SUMMARY OF THE INVENTION
`
`Accordingly, in a ?rst aspect of the present invention, a
`method is used in a selective call radio for receiving a radio
`signal transmitted on a ?rst radio channel. The radio signal
`has a plurality of messages included in a plurality of control
`frames and data frames. each of the plurality of messages
`having an address signal and related message information.
`Each control frame includes an address ?eld and an infor
`mation ?eld. The address ?eld of a control frame has a set
`of address signals. Each of the set of address signals includes
`a subvector and an address indicating, respectively, a posi
`
`65
`
`A known technique of organizing information for com
`munication to selective call radios such as pagers in a radio
`communication system is to arrange the addresses of selec
`tive call radios for which message information is included in
`a predetermined portion of a transmission cycle. such as a
`frame, at the beginning of the predetermined portion of the
`transmission cycle in an address ?eld, separated from the
`message information intended for the selective call radios.
`This has the advantage of improving the battery life of the
`selective call radios, because a radio which has no informa
`tion in the predetermined portion of the transmission cycle
`can quickly revert to a low power mode as soon as it
`determines its address is not in the address ?eld.
`When the addresses are positioned at the beginning of the
`predetennined portion of the transmission cycle, the position
`of the message information intended for the selective call
`radios must be determined by the selective call radios in
`35
`order for them to recover the message information. A
`technique for determining the position of the information is
`used in the well known FLEXTM protocol of Motorola, Inc.
`of Schaumburg, Ill. In this protocol a starting position of
`message information within the predetermined portion of the
`transmission cycle is indicated by a vector which has a
`length and position determined on a one for one basis by the
`length and position of the address associated with the vector.
`While this protocol works quite well, it has limitations. One
`limitation is that, as channel arrangements have become
`more sophisticated, the amount of information required in a
`vector requires a longer vector than the associated address.
`Another limitation is that the message information must be
`within the same predetermined portion of the transmission
`cycle. This other limitation arises partly from the limitation
`on the length of the vectors due to their correspondence to
`the length of the addresses in the FLEXTM protocol.
`Thus, what is needed is an improved technique for orga
`nizing message information in a radio communication sys
`tem.
`
`45
`
`50
`
`55
`
`2
`tion of a data packet within the control frame and one of a
`plurality of selective call radios associated with the data
`packet. The information ?eld follows the address ?eld and
`has a set of data packets. Each data packet in the set of data
`packets has the position of the data packet indicated by at
`least one subvector within the control frame. Each data
`packet in the set of data packets is one of a vector packet and
`a short message packet. Vector packets indicate starting
`positions of long messages within the plurality of control
`frames and data frames.
`The method includes the steps of: receiving the radio
`signal; determining a presence of a ?rst address within the
`address ?eld in the control frame received in the radio
`signal, when the ?rst address matches an embedded address
`assigned to the selective call radio; determining a ?rst
`subvector included with the ?rst address; decoding a starting
`position of a ?rst data packet indicated by the ?rst subvector;
`recovering the ?rst data packet at the starting position of the
`?rst data packet; decoding a starting position of a ?rst long
`message when the ?rst data packet is a vector packet; and
`processing the ?rst long message beginning at the starting
`position of the ?rst long message.
`Accordingly, in a second aspect of the present invention,
`a selective call radio is used for receiving a radio signal
`transmitted on a ?rst radio channel. The radio signal has a
`plurality of messages included in a plurality of control
`frames and data ?'ames. Each of the plurality of messages
`has an address signal and related message information. Each
`control ?'ame includes an address ?eld and an information
`?eld. The address ?eld of a control frame has a set of address
`signals. Each of the set of address signals includes a sub
`vector and an address indicating, respectively, a position of
`a data packet within the control frame and one of a plurality
`of selective call radios associated with the data packet The
`information ?eld follows the address ?eld and has a set of
`data packets. Each data packet in the set of data packets has
`the starting position of the data packet indicated by at least
`one subvector within the control frame. Each data packet in
`the set of data packets is one of a vector packet and a short
`message packet. Vector packets indicate starting positions of
`long messages within the plurality of control frames and
`data frames.
`The selective call radio includes a receiver, an address
`decoder, a subvector element, a data packet position
`element, a data packet buffer, a protocol position decoder,
`and a long message processor. The receiver receives the
`radio signal. The address decoder, which is coupled to the
`receiver, determines the presence of a ?rst address within the
`address ?eld in a control frame received in the radio signal
`When the ?rst address matches an embedded address
`assigned to the selective call radio. The subvector element,
`which is coupled to the receiver and the address decoder,
`determines a ?rst subvector associated with the ?rst address
`present within the address ?eld. The data packet position
`decoder, which is coupled to the subvector element, decodes
`a starting position of a ?rst data packet indicated by the ?rst
`subvector. The data packet buffer, which is coupled to the
`receiver and the data packet position decoder, recovers the
`?rst data packet at the starting position of the data packet.
`The protocol position decoder, which is coupled to the data
`packet buffer, decodes a starting position of a ?rst long
`message when the ?rst data packet is a vector packet. The
`long message processor, which is coupled to the receiver and
`the protocol position decoder, processes the ?rst long mes
`sage at the starting position of the long message.
`Accordingly, in a third aspect of the present invention, a
`method is used in a system controller for generating a radio
`
`General Electric Co. 1008 - Page 11
`
`

`
`5,644,568
`
`3
`signal transmitted on a ?rst radio channel. The radio signal
`has short and long messages included in a plurality of
`control frames and data frames. Each of the short and long
`messages has an address signal and related message infor
`mation.
`The method includes the steps of generating each address
`?eld; generating an information ?eld; assembling each con
`trol frame; assembling each data frame; and transferring the
`control frames and data frames to a transmitter for radio
`transmission. In the step of generating each address ?eld,
`each address ?eld of a control frame is generated having a
`set of address signals. Each of the set of address signals
`includes an address and a subvector indicating, respectively,
`a selective call radio for which one of the short and long
`messages is intended, and a starting position of a data packet
`within the control frame. In the step of generating an
`information ?eld. an information ?eld following the address
`?eld and having a set of data packets is generated. Each data
`packet in the set of data packets has the starting position of
`the data packet indicated by at least one subvector within the
`control frame. Each data packet in the’ set of data packets is
`one of a vector packet and a short message packet. Vector
`packets indicate starting positions of long messages within
`the plurality of control frames and data frames. In the step
`of assembling each control frame, each control frame is
`assembled including an address ?eld and an information
`?eld. In the step of assembling each data frame, each data
`frame is assembled including a set of long messages. Each
`long message in the set of long messages has a starting
`position indicated by at least one vector packet in a control
`frame.
`Accordingly, in a fourth aspect of the present invention. a
`system controller is used for generating a radio signal
`transmitted on a ?rst radio channel. The radio signal has
`short and long messages included in a plurality of control
`frames and data frames. Each of the short and long messages
`has an address signal and related message information.
`The system controller includes a control frame element,
`an address ?eld element, an information ?eld element, a data
`frame element. and a cell site controller. The control frame
`element assembles each control frame including an address
`?eld and an information ?eld. The address ?eld element,
`which is coupled to an outbound message memory which
`stores the short and long messages, and which is also
`coupled to the control frame element, generates an address
`?eld of a control frame having a set of address signals. Each
`of the set of address signals includes an address and a
`subvector indicating, respectively, a selective call radio for
`which one of the short and long messages is intended, and
`a starting position of a data packet within the control frame.
`The information ?eld element, which is coupled the out
`bound message memory, the address ?eld element, and to
`the control frame element, generates an information ?eld
`following the address ?eld and has a set of data packets.
`Each data packet in the set of data packets has the starting
`position of the data packet indicated by at least one subvec
`tor within the control frame. Each data packet in the set of
`data packets is one of a vector packet and a short message
`packet. Vector packets indicate starting positions of long
`messages within the plurality of control frames and data
`frames. The data frame element, which is coupled to the
`information ?eld element, assembles each data frame
`including a set of long messages. Each long message in the
`set of long messages has a starting position indicated by at
`least one vector packet in a control ?'arne. The cell site
`controller, which is coupled to the data frame element and
`the control frame element, transfers the control frames and
`data frames to a transmitter for radio transmission.
`
`4
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is an electrical block diagram of a radio commu
`nication system, in accordance with a preferred embodiment
`of the present invention.
`FIG. 2 is an electrical block diagram of a system control
`ler used in the radio communication system, in accordance
`with a preferred embodiment of the present invention.
`FIGS. 3, 4, and 5 are timing diagrams of frames included
`in a radio signal transmitted by a transmitter in radio
`communication system, in accordance with a preferred
`embodiment of the present invention.
`FIG. 6 is an electrical block diagram of a selective call
`radio used in the radio communication system, in accor
`dance with a preferred embodiment of the present invention.
`FIG. 7 shows a ?ow chart of a method used in the system
`controller, in accordance with a preferred embodiment of the
`present invention.
`FIGS. 8 and 9 show a flow chart of a method used in the
`selective call radio, in accordance with a preferred embodi
`ment of the present invention.
`
`DETAILED DESCRIPTION OF THE DRAWINGS
`
`Referring to FIG. 1, an electrical block diagram of a radio
`communication system 100 is shown in accordance with the
`preferred embodiment of the present invention. The radio
`communication system 100 comprises a message input
`device, such as a conventional telephone 101 connected
`through a conventional switched telephone network (PSTN)
`108 by conventional telephone links 110 to a system con
`troller 102. The system controller 102 oversees the operation
`of at least one radio frequency transmitter/receiver 103 and
`at least one ?xed system receiver 107, through one or more
`communication links 116, which typically are twisted pair
`telephone wires, and additionally can include RF,
`microwave, or other high quality audio communication
`links. The system controller 102 encodes and decodes
`inbound and outbound telephone addresses into formats that
`are compatible with land line message switch computers.
`The system controller 102 also functions to digitally encode
`and schedule outbound messages, which can include such
`information as digitized audio messages, alphanumeric
`messages, and response commands, for transmission by the
`radio frequency transmitter/receivers 103 to a plurality of
`selective call radios 106. The system controller 102 further
`functions to decode inbound messages, including unsolicited
`and response messages, received by the radio frequency
`transmitter/receivers 103 and the ?xed system receivers 107
`from the plurality of selective call radios 106.
`Examples of response messages are aclmowledgments
`and designated response messages. Designated response
`messages are communicated in the inbound channel in
`portions named data units. An acknowledgment is a
`response to an outbound message initiated at the system
`controller 102. An example of an outbound alphanumeric
`message intended for a selective call radio 106 is a page
`message entered from the telephone 101. The acknowledg
`ment indicates successful reception of the outbound mes
`sage. A designated response message is a message sent from
`a selective call radio in response to a command included in
`an outbound message from the system controller 102. An
`example of a designated response message is a message
`initiated by the selective call radio 106, but which is not
`transmitted until after a response command is received ?'om
`the system controller 102. The response command, in turn,
`is sent by the system controller 102 after an inbound
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`message requesting permission to transmit the designated
`response message is communicated from the selective call
`radio 106 to the system controller 102. The response mes
`sages are preferably transmitted at a time designated within
`the outbound message or response command, but alterna
`tively can be transmitted using a non-scheduled protocol,
`such as the ALOHA or slotted ALOHA protocol, which are
`well known to one of ordinary skill in the art.
`An unsolicited message is an inbound message transmit
`ted by a selective call radio 106 without having received an
`outbound message which requires a response. An example
`of an unsolicited message is an inbound message from a
`selective call radio 106 which alerts the radio communica
`tion system 100 that the selective call radio 106 is within
`radio range of the radio communication system 100. An
`unsolicited message can include a request to transmit a
`designated response and can include data such as
`alphanumeric, fax, or digitized voice data. Unsolicited mes
`sages are transmitted using an ALOHA or slotted ALOHA
`protocol. The outbound messages are included in outbound
`radio signals transmitted from a conventional antenna 104
`coupled to the radio frequency transmitter/receiver 103. The
`inbound messages are included in inbound radio signals
`received by the conventional antenna 104 coupled to the
`radio frequency transmitter/receiver 103 and the conven
`tional antenna 109 coupled to the ?xed system receiver 107.
`It should be noted that the system controller 102 is
`capable of operating in a distributed transmission control
`environment that allows mixing conventional cellular,
`simulcast. master/slave, or other coverage schemes involv
`ing a plurality of radio frequency transmitter/receivers 103,
`conventional antennas 104, 109. and ?xed system receivers
`107, for providing reliable radio signals within a geographic
`area as large as a nationwide network. Moreover, as one of
`ordinary skill in the art would recognize. the telephonic and
`selective call radio communication system functions may
`reside in separate system controllers 102 which operate
`either independently or in a networked fashion.
`It should also be noted that the radio frequency
`transmitter/receiver 103 may comprise the ?xed system
`receiver 107 collocated with a conventional radio frequency
`transmitter.
`It will be appreciated that other selective call radio
`devices (not shown in FIG. 1), such as one and two way
`pagers, conventional mobile cellular telephones, mobile
`radio data terminals, mobile cellular telephones having
`attached data tenninals, or mobile radios (trunked and
`non-trunked) having data terminals attached, are also able to
`be used in the radio communication system 100. In the
`following description, the term “selective call radio” will be
`used to refer to the personal radio telephone, the portable
`transmitting/receiving device 106, a mobile cellular
`telephone, a mobile radio data terminal, a mobile cellular
`telephone having an attached data terminal, or a mobile
`radio (conventional or trunked) having a data terminal
`attached Each of the selective call radios assigned for use in
`the radio communication system 100 has an address
`assigned thereto which is a unique selective call address.
`The address enables the transmission of a message from the
`system controller 102 only to the addressed selective call
`radio. and identi?es messages and responses received at the
`system controller 102 from the selective call radio.
`Furthermore. each of one or more of the selective call radios
`also has a unique telephone number assigned thereto, the
`telephone number being unique within the PSTN 108. A list
`of the assigned selective call addresses and correlated tele
`phone numbers for the selective call radios is stored in the
`system controller 102 in the form of a subscriber data base.
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`Referring to FIG. 2, an electrical block diagram of the
`system controller 102 is shown, in accordance with the
`preferred embodiment of the present invention. The system
`controller 102 comprises a cell site controller 202, a message
`handler 204, an outbound message memory 208, a sub
`scriber data base 220, a telephone interface 206, a channel
`assignment element 210, an address ?eld element 212, an
`information ?eld element 214, a data frame element 216,
`and a control frame element 218. The cell site controller 202
`is coupled to the radio frequency transmitter/receivers 103
`(FIG. 1) and ?xed system receivers 107 (FIG. 1) by the links
`116. The cell site controller 202 couples outbound messages
`including selective call addresses to the transmitter/receivers
`103 and controls the transmitter/receivers 103 to transmit
`transmission cycles which include the outbound messages.
`The cell site controller 202 also processes inbound messages
`from the selective call radios 106. The inbound messages are
`received by the transmitter/receivers 103 and ?xed system
`receivers 107, and are coupled to the cell site controller 202.
`The message handler 204, which routes and processes
`messages, is coupled to the telephone interface 206, the
`subscriber data base 220, and the outbound message
`memory 208. The telephone interface 206 handles the
`switched telephone network 108 (PSTN) (FIG. 1) physical
`connection, connecting and disconnecting telephone calls at
`the telephone links 110, and routing the audio signals
`between the telephone links 110 and the message handler
`204.
`The subscriber data base 220 stores information for each
`subscriber, including a correlation between a selective call
`address assigned to each selective call radio 106 and the
`telephone number used within the PSTN 108 to route
`messages and telephone calls to each selective call radio
`106, as well as other subscriber determined preferences,
`such as hours during which messages are to be held back
`from delivery to the selective call radio 106. The outbound
`message memory 208 is for storing a queue of messages
`which are queued for delivery to at least one of the plurality
`of selective call radios 106, wherein each message of the
`queue of messages is associated with a selective call address,
`also stored in the outbound message memory 208, of one of
`the plurality of selective call radios 106 for which each
`message is intended. The message handler 204 schedules
`outbound messages and the selective call addresses associ
`ated therewith within a transmission cycle. The message
`handler 204 also determines response schedules for response
`messages which minimize contention of messages at
`transmitter/receivers 103 and ?xed system receivers 107,
`and includes response timing information in outbound mes
`sages so that selective call radios 106 will respond according
`to the response schedule. The message handler 204 identi?es
`an inbound message as being a response message associated
`with one of the selective call radios in the subscriber data
`base 220, identi?es the response message as being associ
`ated with one of the outbound messages in the outbound
`message memory 208. The message handler 204 then further
`processes the outbound and response messages according to
`their content. The cell site controller 202, the message
`handler 204, the outbound message memory 208, the sub
`scriber data base 220, and the telephone interface 206, are
`conventional elements of the system controller 102.
`As one example of an operation of the system controller
`102, the delivery of an outbound message stored in the
`outbound message memory 208 is completed when the
`outbound message has been communicated to the intended
`selective call radio 106, the message is presented on a
`display of the selective call radio 106 by a user action, a
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`message response is communicated back to the system
`controller 102 ?om the selective call radio 106, and the
`message response is identi?ed by the message handler 204
`as being a user acknowledgment generated by the selective
`call radio 106 speci?cally for the outbound message. In this
`example, the message handler 204 generates another mes
`sage which is sent to the originator of the outbound message
`to notify the originator that the message has been acknowl
`edged by the selective call radio 106.
`Unique functions of the system controller 102 in accor
`dance with the preferred embodiment of the present inven
`tion are included in the channel assignment element 210, the
`address ?eld element 212, the information ?eld element 214,
`the data frame element 216, and the control frame element
`218.
`The address ?eld element 212 is coupled to the subscriber
`data base 220, the outbound message memory 208. the
`information ?eld element 214, and the control frame ele
`ment 218. The information ?eld element 214 is further
`coupled to the outbound message memory 208 and the
`control frame element 218. The control frame element 218
`is further coupled to the cell site controller 202. The channel
`assignment element 210 is coupled to the data frame element
`216. The address ?eld element 212 recovers messages from
`the outbound message memory 208 which have been sched
`uled for transmission in an upcoming transmission cycle.
`The address ?eld element 212 determines. for each recov
`ered message. the associated selective call address (?om the
`subscriber data base 220) and the length of the message. The
`length of the message is coupled to the information ?eld
`element 214.
`When the message information is one of a set of prede
`termined short messages. for example an acknowledgment
`or a response command. or when the message information is
`less than a ?rst predetermined length, which in this example
`is three words long. the message is coupled by the infor
`mation ?eld element 214 to the control frame element 218
`for inclusion as a short message packet into an information
`?eld of a control ?ame being assembled by the control frame
`element 218 at a starting position within the control frame.
`The control frame element 218 couples the starting position
`of the short message to the address ?eld element 212, which
`ge