WO1996027954A1

WO1996027954A1 - A subscriber unit for use in a multiple access communication system

Info

Publication number: WO1996027954A1
Application number: PCT/US1996/003187
Authority: WO
Inventors: Ido Ein-Dor
Original assignee: Geotek Communications, Inc.
Priority date: 1995-03-07
Filing date: 1996-03-07
Publication date: 1996-09-12
Also published as: KR19980702769A; IL112926A0; IL112926A; EP0813773A1; CA2214784A1; EP0813773A4; AU5359896A

Abstract

The invention discloses an apparatus and a method of controlling the scanning features of a mobile subscriber unit (6) used by a subscriber to a communication system, comprising the steps of storing a list of one or more groups (204) to which the subscriber belongs in the mobile subscriber unit, assigning a priority to each of the groups in the list, when a dispatch communication is received, determining the group to which the dispatch is directed and the priority level of the group, and if there is an existing dispatch communication being processed, comparing the priority level of the existing dispatch communication and the priority level of the recently received dispatch communication and enabling the reception of the dispatch communication with the highest priority level.

Description

A SUBSCRIBER UNIT FOR USE IN A

MULTIPLE ACCESS COMMUNICATION SYSTEM

Background of the Invention

The present invention relates to wireless communication systems.

More specifically, it relates to the subscriber units used in mobile wireless

communication systems.

Current efforts in wireless communications, particularly in the segment

of wireless communications referred to as Specialized Mobile Radio (SMR) ,

have the goal of providing greater functionality to the SMR user, commonly

known as a subscriber. These efforts have been limited by problems in the

present SMR equipment. One equipment area where severe Iimitations exist

is in the unit the subscriber uses to communicate, known as the subscriber

unit.

The Iimitations include a problematic electronic architectural design

that hinders the capabilities of the subscriber unit. As a result of this

limitation, the subscriber units are unable to efficiently process the signals

they communicate, including voice and data signals. Further, as a result of

the problematic architecture, the subscriber units are unable to efficiently

handle peripheral devices which may be necessary to efficiently process the

communication signals received by the subscriber unit.

Current subscriber units are also limited in the features that they

provide to their users, thereby causing inefficient use of communications

resources. Many of these Iimitations exist in dispatch communication, wherein businesses that have field employees - employees working outside

the office environment -- communicate with one or more of those employees

at a time. One problem commonly encountered is that the field employees

often must leave their vehicles (where the subscriber units are mounted) in

order to perform their jobs and thus are not always able to hear the

dispatched information on their radio terminals. If the field employee is away

from the vehicle when a message is dispatched, the employee will miss the

dispatched message. Depending on the importance of the message, this can

lead to unfortunate results. This is but one example of the problems with

current subscriber units -- there are many others.

In view of these and other Iimitations, systems and methods for more

efficiently processing dispatched communications, therefore, are needed .

Summary of the Invention

In accordance with the present invention, a new subscriber unit

architecture is utilized. The mobile subscriber unit of the present invention

includes two pieces of equipment, a radio unit and a subscriber terminal. In

accordance with a preferred embodiment of the present invention, the radio

unit is housed in the trunk of an automobile while the subscriber terminal is

housed in the passenger compartment of the automobile.

The radio unit includes a receiver, a transmitter, an input/output

terminal, and processing means. The radio unit processor means processes

the received and transmitted communication signals to provide

communication services information through the radio unit input/output terminal. The subscriber terminal includes an input/output terminal for

communicating with the radio unit input/output terminal, a display for

displaying information to the subscriber, a keypad through which the

subscriber can enter information and processor means. The subscriber

terminal processor means controls the display and the keypad. It also

processes the communication services information supplied by the radio unit.

It is also preferred to provide a second input/output terminal in the subscriber

unit which is controlled by the processor means in the subscriber unit.

Peripheral devices such as magnetic swipe devices, printers, bar code

scanners and serial keyboards can be connected to this second input/output

device and operated under the control of the subscriber unit processor

means.

In accordance with another aspect of the present invention, dispatch

information is transmitted over a wireless communication system and is

processed in a subscriber unit. The subscriber unit stores all dispatch

activity in a memory. Then, when requested by the user of the subscriber

unit, the memory is accessed and a list of information related to the dispatch

communications is displayed along with the time of occurrence for each

dispatch communication. In accordance with a further aspect of the present

invention, the dispatch information can be used to enable the user of the

subscriber unit to call the entity that generated the dispatch communication.

To call that entity, the user selects one of the displayed dispatch activities by cursoring up and down the list and then selecting the appropriate key.

The subscriber unit then causes a call to be made to the source of the

selected dispatch communication.

As part of a dispatch scanning function performed by the subscriber

unit, the subscriber unit stores a list of one or more groups to which the

subscriber is assigned to and, when a dispatch communication is received,

the subscriber unit determines the group to which the dispatch is directed

and informs the subscriber of the group. In accordance with yet another

aspect of the present invention, this dispatch scanning function is modified

to perform priority scanning, scan nuisance delete and time scan disable.

In priority scanning, a priority level is assigned to each group and is

stored by the subscriber unit in the list of assigned groups. Whenever a

dispatch communication is received, the subscriber unit determines the

group to which the dispatch is directed and then accesses the table of

assigned groups and group priority levels. If there is an existing dispatch

communication being processed when a new dispatch communication is

received which is directed to one of the subscriber's groups, the subscriber

unit compares the priority level of the existing dispatch communication and

the priority level of the newly received dispatch communication and enables

the reception of the dispatch communication with the highest priority level.

In scan nuisance delete, during times when there is excess and

unwanted dispatch communication traffic to a group to which the subscriber unit is assigned, the subscriber can select that group and delete it from the

list which the subscriber unit maintains as part of the scanning function.

The subscriber unit then does not scan for dispatches to that group, thereby

eliminating the nuisance traffic.

In time scan disable, the subscriber can program the subscriber unit to

stop scanning the list of groups to which the subscriber unit is assigned and

then, after a selected period of time, enable the subscriber unit to

automatically start the scanning process again.

The invention will now be described in connection with certain

illustrated embodiments; however, it should be clear to those skilled in the

art that various modifications, additions and subtractions can be made

without departing from the spirit and scope of the claims.

Description of the Drawings

FIG. 1 illustrates a wireless communication system having a base

station, a dispatch station and a plurality of subscriber units;

FIG. 2 illustrates the air interface utilized by the base station, the

dispatch station and the subscriber units to communicate;

FIG. 3 shows a block diagram of the subscriber unit, including the

radio unit and the subscriber terminal;

FIG. 4 illustrates an external view of the subscriber terminal;

FIG. 5 illustrates the circuitry of the subscriber terminal;

FIG. 6 illustrates the circuitry of the radio unit; FIGS. 7 and 10 illustrate various screens shown on the display of the

subscriber terminal during the dispatch mode;

FIG. 8 illustrates the distribution of dispatch group information to

subscriber units;

FIG. 9 illustrates the steps taken by the subscriber unit upon reception

of a dispatch and the steps taken to display the dispatch history;

FIG. 1 1 illustrates steps taken by the subscriber unit in implementing

the last dispatch function;

FIG. 1 2 illustrates the steps taken by the subscriber unit to perform

priority scanning;

FIG. 1 3 illustrates the steps taken by the subscriber unit to perform

scan nuisance deletion; and

FIG. 14 illustrates the steps taken by the subscriber unit to perform

time scan deletion.

Description of the Preferred Embodiment

Referring to FIG. 1 , a communication system 1 is illustrated. The

system 1 includes a base station 2, a dispatch station 4 and a plurality of

subscriber units 6. The communication system 1 may be a frequency

hopping system which is divided into sectors 8 to 1 0 wherein sets of

frequencies are reused in each sector to provide wireless communications.

Note, however, that the present invention may be used on other types of

communication systems, including TDMA systems, CDMA systems and even analog based systems.

The base station 2 includes the communication equipment necessary

to provide the multiple access communications for the plurality of

subscribers units 6 and for the dispatch station 4. The base station 2 also

includes the communication equipment needed to provide communications

through the Public Switched Telephone Network (PSTN) .

The dispatch station 4 includes equipment necessary to dispatch

communications from the dispatch station 4 to a number of subscriber units

6, commonly referred to as point-to-multipoint communications, and it also

includes equipment that provides point-to-point communications. The

subscriber units 6 generally consist of mobile or portable equipment

necessary to transmit, receive and process communication signals.

Referring to FIG. 2, the communication links between the base station

2, the dispatch station 4 and the subscriber units 6 -- referred to as the

common air interface - are illustrated. The communication channels in FIG.

2 include a plurality of traffic channels (TCHs), at least one control channel

(CCH) and at least one access channel (ACH) . In the communication system

1 of FIG. 1 , all of these channels are present in each sector 8 to 10. The

TCHs operate in the uplink (transmissions from subscriber units 6 to the base

station 2) and in the downlink (transmissions from the base station 2 to the

subscriber units 6) . The CCH and the ACH, however, operate only in one

direction -- the CCH in the downlink and the ACH in the uplink. In the illustrated embodiment of FIGS. 1 and 2, ten 25 kHz frequency

channels are used to define ten uplink channels and ten 25 kHz frequency

channels are used to define ten downlink channels. In each sector 8 to 10,

nine of the frequency channels are used to implement nine uplink TCHs and

nine of the frequency channels are used to implement nine downlink TCHs.

In each sector, the remaining frequency channels are used to transmit one

ACH and one CCH. Voice information, data information and inband

overhead control signals between the base station 2 and the subscriber units

6 are transmitted over the TCHs, preferably using frequency hopping and

time hopping communication methodology - - but any communication

method and any air interface may be used. Timing and control signals from

the base station 2 to the subscriber unit 6 are transmitted on the CCH.

Status and operational requests from the subscriber unit 6 to the base

station 2 are transmitted on the ACH . The common air interface of FIG. 2 is

also used in communications between the base station 2 and the dispatch

station 4.

Now that the communication system in which the subscriber unit 6 of

the present invention operates has been described, the subscriber unit 6 will

be described. Referring to FIG. 3, the subscriber unit 6 of the present

invention is divided into two pieces of equipment, a radio unit 1 2 and a

subscriber terminal 14. In general, the radio unit 1 2 transmits and receives

communication signals to and from the base station 2, the dispatch station 4 or other subscriber units 6 through a pair of antennas 1 5 and 1 6 under the

control of the subscriber terminal 1 4.

The radio unit 1 2, as will be seen in greater detail in later discussions

and figures, provides the processing power needed to transmit and receive

by performing essential communication processes. For example, the radio

unit 1 2 performs the needed signal processing on transmit and receive

signals, such as voice coding, error correction encoding, interleaving, Viterbi

decoding, frequency hopping, time hopping, automatic gain control,

automatic frequency modulation, diversity reception processing and

modulation. The radio unit 1 2 also determines whether communications are

voice communications, data communications or dispatch communications as

well as various attributes concerning these communication type and uses

this information to generate information about the communication services

being provided. This list will vary from communication system to

communication system, however, the architecture of the present invention

requires that the processing necessary to the communication system being

used be included in the radio unit 1 2.

The radio unit 1 2, therefore processes the received and transmitted

communication signals to provide communication services information. This

information is provided to the subscriber terminal 14 through the interfaces

1 7 and 1 8. The subscriber unit 1 4 provides a keypad and display interface

to a subscriber and receives the communication services information from the radio unit 1 2. The subscriber unit 1 4 also has a processor that controls

the display and the keypad and also processes the communication services

information provided by the radio unit 1 2.

The architecture of FIG. 3 is a client-server architecture wherein the

subscriber terminal 14 is the client and the radio unit 1 2 is the server that

serves the communication needs of the client the subscriber terminal 1 4. In

the architecture of FIG. 3, the functions which provide an interface between

communication services (voice transmit, voice receive, dispatch, data

transfer, etc.) and the subscriber are performed by the subscriber terminal 1 4

while the functions which are necessary to interface to the communication

system 1 to provide communication services are performed by the radio unit

1 2. Then when the subscriber requires the use of a communication service,

the subscriber terminal 14 requests access to that service through the radio

unit 1 2 and it is provided.

FIGS. 4 to 6 illustrate various aspects of the subscriber unit 6. In

FIG. 4, an external view of a subscriber terminal 1 4, which is preferably

positioned next to the subscriber in the passenger compartment of a vehicle,

is illustrated. The subscriber terminal 1 4 includes a display 24, a keypad 26

and a handset 28. The keypad 26 includes five keys 30 to 34, commonly

referred to as soft keys, whose function is defined by the features shown on

the bottom of the display 24. The keypad 26 also includes a plurality of

keys 36 to 43 having a variety of functions. Each of the keys 36 to 41 is positioned next to a LED display 44 which is illuminated when the function

associated with the key is enabled. The handset 28 includes a numeric

keypad and the keys necessary to start and end a communication session.

The handset 28 also has the traditional push-to-talk button found on many

radio units.

In FIGS. 5 and 6, the processing circuitry of the subscriber terminal 14

and the radio unit 1 2, respectively, is illustrated. Referring to FIG. 5, the

subscriber terminal 14 includes a microprocessor 50, an oscillator circuit 52,

a power supply circuit 54, a serial interface circuit 56, a display driver circuit

58, a memory circuit 60, a keyboard interface circuit 62, an I/O decoder

circuit 64, a LED driver 66 and an interface circuit 68. The subscriber

terminal 14 can also include a real time clock 70, however, in a preferred

embodiment, the base station 2 distributes real time clock information during

its transmission to each of the subscriber units 6. In this preferred

embodiment, the microprocessor 50 extracts the real time clock information

from signals transmitted by the base station 2 and stores it in the memory

circuit 60. This information is combined with timing information generated

by the oscillator circuit 52 to provide the subscriber terminal 1 4 with real

time clock information. If the base station 2 distributed real time clock

information is utilized, then the real time clock 70, its back up power source,

the battery 72 and the battery management circuit 72 and 74 in the power

supply circuit 54, can be eliminated. The memory circuit 60 includes a decoder circuit 76, an address latch

78, a boot ROM 80, a flash memory 82 and a static RAM 84. The boot

ROM 80 stores the code necessary to initialize the microprocessor 50 and

the circuitry of the subscriber terminal 14 as well as code necessary to

download future software versions for the subscriber terminal 14. The flash

memory 82 is non-volatile re-writable memory which is utilized to store

information which must be maintained even during a loss of power. The

static RAM 84 is utilized as a working memory as needed.

The display driver circuit 58 includes the LCD display 24, a power

supply 86, a LCD controller 88, a memory circuit 90 and an address

controller 92. The display driver circuit 58 is accessed by the

microcontroller 50 via the I/O decoder 64. The information to be displayed

is downloaded from the microprocessor 50 to the memory circuit 90. The

display of the information on the display 24 is then controlled in a

conventional manner by the LCD controller 88.

The microprocessor 50 is responsive to the selection of the keys 30 to

34 and 36 to 43, as well as to the selection of the keys on the handset 28.

When the keys are selected, selection signals are processed through the

keyboard interface circuit 62 to the microprocessor 50. The microprocessor

50 also controls the LEDs 44 through the LED driver circuit 66. The RS-232

interface 94 provides communications between the subscriber terminal 1 4

and external devices, such as notebook computers, magnetic swipe devices used to read magnetic strips, printers, bar code readers and serial keyboards.

The RS-485 interface 96 and the interface circuitry 68 provides

communications between the subscriber terminal 1 4 and the receiver and

transmitter circuitry of the radio unit 1 2 (shown in FIG. 6) .

In FIG. 6, the circuitry of the radio unit 1 2 is illustrated. The radio unit

12 includes antennas 102 and 104, a radio board 106, a baseband unit 1 08,

a service board 1 10, and a GPS interface 1 1 1 . The radio unit circuitry

illustrated in FIG. 6, except the antennas 102 and 1 04, in a preferred

embodiment, is housed separately from the subscriber terminal 14, for

example, inside the trunk of an automobile. The antennas 1 02 and 1 04 are

preferably mounted externally on the automobile.

The radio board 106 includes transmitter and receiver circuitry. More

particularly, it includes a transmitter 1 1 2, two receiver channels 1 14 and

1 1 6, a duplexer 1 1 8, a frequency synthesizer 1 20, gain and frequency

control circuitry 1 22 and transmitter gain control circuitry 1 24. As

previously describer, the circuitry of the radio board 106 provides

communication via frequency hopping, that is, a communication signal is

transmitted and received by hopping the signal over several different

frequency channels.

The radio board 106 is interfaced with the baseband unit 1 08. The

baseband unit 1 08 includes a modem 1 26, a controller 1 28, a voice

processing package 1 30 and an interface circuit 1 32 to the subscriber terminal's 1 4 circuitry. This baseband unit 1 08 receives the signals to be

transmitted to the base station 2 from the subscriber terminal 14 and sends

the signals to the transmitter 1 1 2 in the radio board 1 06 for transmission.

This baseband unit 1 08 also receives the signals that the radio board 106

receives from the base station 2, performs some processing on the received

signals and sends them to the subscriber terminal 14 through the interface

1 32.

The subscriber terminal 1 4 has several operational modes, one of

which is the dispatch mode. When a subscriber selects the DISP KEY 41 on

the subscriber terminal 1 4, the microprocessor 50 causes the subscriber

terminal 1 4 to enter the dispatch mode, thereby allowing the subscriber to

view information concerning the dispatch communications on the display 24.

Upon entering the dispatch mode, the microprocessor 50 preferably causes

the screen shown in FIG. 7 to be displayed on the display 24 . The screen

preferably has at least seven sequentially numbered lines. The second line

of the display 24 displays the word "DISPATCH" , indicating that the

subscriber terminal 14 is in the dispatch operational mode.

The subscriber unit 6 of the present invention allows subscribers to be

divided into groups and, if desired, into subgroups as the dispatcher desires.

For example, all subscribers that respond to the dispatch station 4 could be

grouped according to their job function and subgrouped according to their

regional responsibilities. In this example, if the dispatcher is communicating with sales, service and delivery personnel, the dispatcher could assign all

sales personnel to a first group, all service personnel to a second group and

all delivery personnel in a third group. Then, calls which only concern sales

personnel can be directed to the first group and so on.

Referring to FIG. 8, the process of distributing the group and subgroup

information to the subscriber units 6 is illustrated. In step 200, the grouping

and, if desired, the subgrouping desired by the dispatcher is transmitted from

the dispatch station 4 to the base station 2 over a TCH. The base station 2

updates a subscriber database that it maintains and then, in step 202,

transmits the group and subgroup information to all of the subscriber units 6

over a CCH. The group and subgroup transmitted by the base station 2 to

the subscriber unit 6 are preferably stored in the radio unit 1 2 in memory in

the controller 1 28 circuitry in step 204. It is possible for the subscriber to

be assigned to multiple groups or multiple subgroups, in which case each of

the assigned groups is stored in the controller 1 28. It is further preferred

that the dispatcher 4 be able to modify the assigned groups and subgroups

at any time by the method of FIG. 8. Whenever the grouping information is

transmitted, the controller 1 28 will receive this transmitted information and

store a new grouping and sub-grouping in its memory upon receipt.

When a subscriber belongs to more than one group, the subscriber

can cause the subscriber terminal 1 4 and the radio unit 1 2 to enter the scan

mode. The controller 1 28 in the radio unit 1 2 stores a list of the groups that a subscriber is assigned to. When in the scan mode, the controller 1 28

compares the group that a dispatch communication is directed to with the

groups in the controller's 1 28 list. If there is a match, then the controller

enables reception of that dispatch. If the group that the dispatch is directed

to is not on the controller's 1 28 list, then the controller 1 28 does not enable

reception of the dispatch.

Information concerning the dispatch group and subgroup that a

dispatch transmission is directed to is displayed on the third and sixth lines

of the display 24 shown in FIG. 7. In FIG. 7, the " 1 2a" (or just " 1 2" if

subgroup information is not being used) on the third line indicates the active

group and subgroup of the subscriber unit 1 6. The " 1 2" indicates the group

and the "a" indicates the subgroup. The active group is the group which the

subscriber can both hear and transmit to in the dispatch mode. The "3c" on

the sixth line, just above the label LAST, indicates the last group and

subgroup on which there was a dispatch call. The "5a" on the sixth line,

just above the label PICK, indicates the group and subgroup to which an

incoming dispatch is directed.

The items displayed on the seventh line of the display of FIG. 7 define

the functions of the soft keys 30 to 34. In the dispatch mode, as shown in

FIG. 7, the soft keys are defined as follows: the first soft key 30 (labeled

"SCAN") implements the previously discussed scanning function, the second

soft key 31 (labeled "PICK"), when selected, allows the subscriber to change the active group as displayed on the third line of the display to the group

displayed just above the PICK label (5a in FIG. 7) , the third soft key 32

(labeled " 1 TO 1 ") implements a function which is not relevant to this

invention, the fourth soft key 33 (labeled "HIST") implements a dispatch

communication processing function in accordance with one aspect of the

present invention and the fifth soft key 34 (labeled "LAST") implements

another dispatch communication processing function in accordance with

another aspect of the present invention.

Before further describing the functions performed when the HIST and

LAST soft keys are selected by the subscriber, some of the background

processing performed by the subscriber terminal 1 4 and the radio unit 1 2 will

be described. FIG. 9 illustrates some of the steps taken by the radio unit 1 2

and the subscriber terminal 1 4 each time a communication is received. In

step 300, the radio terminal 1 2 determines whether the transmission is a

dispatch communication. To allow the radio terminal 1 2 to perform step

300, the base station 2 adds control bits to transmitted communication

signals on the CCH that match a predetermined sequence when the

communication is a dispatch communication. The controller 128 processes

each communication signal received by the radio unit 1 2 to determine the

status of the control bits added to the communication signal by the base

station 2. The controller 1 28 compares these control bits to the

predetermined sequence which is stored in the controller 1 28 memory to determine whether the received communication signal is a dispatch

communication.

If the communication is not a dispatch communication, then the

controller 1 28 exits the processing routine of FIG. 9 to perform other tasks

on the receive communication signals. On the other hand, if the

transmission is a dispatched communication, then, in step 302, the controller

1 28 accesses the control information in the communication signal to

determine the group and subgroup (or groups and subgroups) that the

dispatch communication is directed to. Then in step 304, the controller 1 28

accesses its memory to determine which groups and/or which subgroups the

subscriber is allowed access to and compares this to the information

contained in the dispatch communication. In essence the controller 1 28

determines whether the base station 2 has indicated that the subscriber

belongs to the group.

If the subscriber is not permitted access to the dispatch, then the

controller 1 28 exits this process to perform other tasks. If the subscriber is

permitted access to the dispatch communication, then the controller 1 28

checks to see if the scan function is enabled or if the group is the active

group. If either the scan function is enable or the group is the active group,

the controller 1 28, in step 306, causes the dispatch communication signal to

be sent from the radio unit 1 2 to the subscriber terminal 14. Otherwise, this

process is exited. In step 308, in the subscriber terminal 1 4, the microprocessor 50

scans the static RAM 84 which stores various information relating to the

past dispatch communications received by the subscriber terminal 14 which

have been directed to a group and/or a sub-group that the subscriber has

been assigned to. The information stored includes the group and subgroup

of the dispatch communication as well as the time of the dispatch

communication. The microprocessor 50 determines whether there has been

a dispatch communication directed to the same group as the present

dispatch communication within a predetermined time period, preferably

within the last minute. If the microprocessor 50 determines that there has

been a dispatch communication directed to the group within the last minute,

the microprocessor 50 exits this routine. If, however, there has been no

dispatch sent to this group within the last minute, the microprocessor 50

continues to step 31 0 to process the dispatch communication. The purpose

of step 308 is to prevent rapidly repeated dispatch communications within a

group from being stored and displayed to the subscriber thus overwhelming

the history function.

In step 31 0, the dispatch communication is time tagged by the

microprocessor 50. The microprocessor 50 can time tag the dispatch either

by accessing the real time clock 70 or by utilizing real time clock information

that is distributed by the base station 1 0. After the time tagging, in step

31 2, the microprocessor 50 stores information associated with the dispatch communication in the static RAM 84. The stored information includes the

group, subgroups and the time tag associated with he dispatch

communication.

In accordance with the present invention, the subscriber can access

the stored information concerning dispatch communications by selecting the

fourth soft key 33 which is labeled "HIST" in the dispatch operational mode.

When the HIST key is selected and the subscriber terminal 1 4 is in the

dispatch operational mode, the microprocessor 50 preferably causes the

subscriber terminal 1 4 to implement a function whereby a history of

information concerning or relating to the dispatch communications is

displayed to the subscriber. When the HIST soft key 33 is selected, the

microprocessor 50 causes the screen illustrated in FIG. 10 to be shown on

the display 24. The second line of the display of FIG. 8, "DISP: CALL

HISTORY", indicates that the subscriber terminal 14 is in the history mode.

Then, on lines 4 to 6, information relating to the last three dispatch

communications is displayed. The displayed information includes the group

to which each dispatch communication was directed as well as the time that

the dispatch communication was received. Also, the subgroup can be

displayed. In a preferred embodiment, the subscriber can access the last ten

dispatch communications that have information stored in memory by using

the cursor up and cursor down keys 42 and 43 to cause the microprocessor

50 to display additional items from the lists of information that do not fit onto the display 24.

The microprocessor 50 causes this information to be displayed by

accessing the static RAM 84, retrieving the listing of stored information

relating to past dispatch communications, including the associated group and

time tags, and sending the information to the display 24 through the display

driver circuit 58. Referring to FIG. 1 0, it can be seen that the subscriber can

determine that the last dispatch communications received by the subscriber

unit 1 6 were directed to a variety of groups at a variety of times. In

particular, in this example, the display indicates to the subscriber that

dispatch communications were sent to Group 3 at 1 1 : 14 a.m. , to Group 9

at 1 0:58 a.m. and to the Sales Group at 9: 1 2 a.m.

The arrows on line 4 of FIG. 1 0 indicate that the user of the radio

terminal 22 can scroll up and down the displayed listing of dispatch

information by using the keys 43 and 42, respectively. The subscriber

terminal 1 4 of the present invention also enables the subscriber to make a

call to the source of any of the dispatch communications. This is

accomplished by scrolling to the line where information relating to the

desired dispatch is displayed and then pressing a Push-to-Talk (PTT) button

on the subscriber unit 1 6, which is located on the handset 28 of the radio

terminal. The selection of the PTT button is recognized by the

microprocessor 50 which then causes a main screen to be displayed as well

as causing the transmission to occur, as described in the following. Upon recognition of the selection of the PTT button, the microprocessor 50

determines which group the subscriber wishes to communicate with by

accessing the memory 84 to see which listed dispatch communication the

subscriber has selected. This information is passed to the radio unit 1 2

where the controller 1 28 formats a communication signal to be directed to

the dispatch group which the subscriber selected. Communication signals

are then sent by the transmitter 1 1 2.

In accordance with another aspect of the present invention, the

subscriber can easily change the active group of the subscriber unit -

displayed on the third line of the display 24 - to the last group - the group

that was just previously active on the subscriber terminal 1 4 which is

displayed just above the LAST softkey - by selecting the fifth soft key 34

which is labeled "LAST" while in the dispatch operational mode. The last

group then becomes what was the active group. As an example, in FIG. 7,

1 2a is the active group and 3c is the last group. If a subscriber selects the

LAST softkey, 3c becomes the active group and 1 2a becomes the last

group.

Referring to FIG. 1 1 , This function is accomplished in the subscriber

terminal 14 by the microprocessor 50. The microprocessor 50 maintains the

active group and the last group in memory 84. The microprocessor 50, in

step 350, senses the selection of the LAST softkey and then, in step 352,

causes the active group and the last active group stored in the memory 84 to be toggled . The microprocessor 50 also causes the groups shown in the

display 24 to be toggled. This allows a subscriber to quickly respond to a

dispatch communication from another group.

Referring to FIG. 1 1 , steps 354 to 364 illustrate the other steps

performed by the subscriber terminal 1 4 in implementing the last dispatch

function. In step 354, the microprocessor 50 determines when a dispatch is

received. When a dispatch is received, in step 356, the microprocessor 50

determines whether the PICK softkey is selected. If the PICK softkey is not

selected, the microprocessor 50 causes the group to which the incoming

dispatch was directed to become the last group, but the active group is not

changed. As an example, if the active group was 9, the last group was 6

and the group to which the incoming dispatch was directed was 3, the last

group would be changed to 3, but the active group would remain 9 if the

PICK softkey is not selected.

If the PICK softkey is selected, then in step 360, the microprocessor

50 changes the active group to the group to which the incoming dispatch is

directed and changes the last group to what was the active group. As an

example, if the active group was 9, the last group was 6 and the group to

which the incoming dispatch was directed was 3, then the last group would

be changed to 9 and the active group would be changed to 3.

If a new group is manually selected by a subscriber using keys on the

handset 28, the microprocessor 50 senses the selection in step 362. Then in step 364, the microprocessor 50 causes the active group to be changed

to the manually selected group and causes the last group to be changed to

the previously active group. As an example, if the active group was 9, the

last group was 6 and the manually selected group was 4, then the active

group would be 4 and the last group would be 9. In an alternative

embodiment, in step 364, the microprocessor 50 changes the active group

to the manually selected group but does not change the last group. In the

above example, the active group would again be changed to 4 but the last

group would remain 6.

Referring now to FIG. 1 2, the steps performed by the controller 1 28 in

the radio unit 1 2 to implement the priority scan function are illustrated. In

step 400, the controller 1 28 determines whether a received signal is a

dispatch communications. If it is not, the controller 1 28 performs other

functions. If the received signal is a dispatch communication, then the

controller 1 28 determines the group to which the dispatch communication is

directed by accessing the control information associated with the

communication.

Then in step 404, the controller 1 28 accesses its memory to

determine whether the subscriber unit 6 belongs to the group to which the

dispatch communication is directed . Recall that this information is

transmitted by a dispatch station 4 through the base station 2 to the

subscriber terminal 14. If the subscriber unit 6 finds that it does not belong to the group, then the controller 1 28 goes on to perform other functions.

On the other hand, if the subscriber unit 6 finds that it does belong to the

group, then the controller 1 28 checks to see if the scan function is enabled.

Then, if scan is enabled, in step 406, determines whether there is a prior

dispatch communication being processed. If there is no prior dispatch

communication being processed, then the controller 1 28 goes on to perform

other functions, such as processing the current dispatch communication. If

there is a prior dispatch communication being processed, then the controller

1 28 determines whether the subscriber has selected priority scan or not.

The subscriber selects priority scan from the subscriber terminal 1 4 by

selecting the SETUP button 39 on the keypad 26. During the setup routine,

the subscriber will be given the option of enabling or disabling priority scan.

The subscriber terminal 14 transmits control signals to the radio unit 1 2 that

indicate the status of priority scan which are stored in the memory of the

radio unit 1 2. If priority scan is enabled, as part of the setup, the subscriber

will be able to assign a priority level to each group to which he is assigned.

Alternatively, the dispatcher can assign a priority level to the group and

transmit that information with the group assignments to the base station 2

and ultimately to the subscriber units 6. In any event, the controller 1 28, in

addition to storing the group assignments, stores the priority level of the

group in its memory. In a preferred embodiment, there are two priority

levels, high and low. In an alternate embodiment, there are a plurality of priority levels which can be assigned to each of the groups.

Referring back to FIG. 1 2, if priority scan has been disabled, then

after step 408 the controller 1 28 performs other tasks. If, however, priority

scan has been enabled, then in step 410, the controller 1 28 accesses the

priority level of the dispatch communication being processed and the priority

level of the newly received dispatch communication. The controller 1 28

then compares these priority levels. If the priority level of the newly

received dispatch communication is less than or equal to the priority level of

the dispatch communication being processed, then the controller 1 28 goes

on to perform other processing steps. If, however, the priority level of the

newly received dispatch communication is greater than the priority level of

the dispatch communication being processed, the controller 1 28 in step 41 2

causes the newly received dispatch communication to be received by the

subscriber on the subscriber terminal 1 4.

Referring now to FIG. 1 3, the steps performed by the controller 1 28 in

the radio unit 1 2 when implementing the scan nuisance delete function are

illustrated. In step 440, the controller 1 28 determines whether the

subscriber has enabled the scan nuisance delete function.

In a preferred embodiment, this function is enabled or disabled by the

subscriber during the setup mode. As before, the subscriber enters the

setup mode by selecting the SETUP button 39 on the keypad 26. During

setup, the subscriber will be prompted to either enable or disable the scan nuisance function. If the scan nuisance function is enabled, the subscriber

will also be prompted to enter one or more groups which are to be deleted

and to enter a length of time.

Referring back to FIG. 1 3, the subscriber terminal 14 transmits control

information to the radio unit 1 2 that indicates whether the scan nuisance

delete function is enabled or disabled and if enabled, which group or groups

are to be deleted and a length of time the deletion shall be implemented.

The controller 1 28 receives this information and, in step 442, determines

which group or groups to delete from the scan list. In step 444, the

controller 1 28 determines the length of time the group or groups shall be

deleted from the scan list.

Next, in step 446, in a preferred embodiment, the controller 1 28

prompts the subscriber terminal 1 4 to ask the subscriber for a password that

indicates that the subscriber is authorized to enable the scan nuisance delete

function. If the subscriber enters an incorrect password, then the controller

1 28 proceeds to other processing steps. If the subscriber enters a correct

password, then in step 448 the controller 1 28 causes the group or groups

selected by the subscriber to be deleted from the scan list for the length of

time selected by the subscriber. Then, in step 450, the controller 1 28, after

the passage of the selected length of time, causes the deleted group or

groups to be added back to the scan list.

In accordance with another preferred embodiment, the controller 1 28 checks the priority of each of the groups selected for temporary deletion.

This priority can be set as previously described - either by the subscriber or

by the dispatcher at the dispatch station. When the scan nuisance delete

function is enabled, the controller 1 28, before deleting any groups from the

scan list, checks the priority of each of the groups selected for deletion. If

the priority exceeds a predetermined threshold which is preferably set by the

dispatcher at the dispatch station 4, then that group is not deleted from the

scan list by the controller 1 28. Then the controller 1 28 sends a control

signal to the subscriber terminal 1 4 to inform the subscriber that the group

could not be deleted because of its priority level.

Referring to FIG. 14, the steps performed by the subscriber unit 6 to

implement the time scan disable function are illustrated. In step 460, the

controller 1 28 determines whether the time scan disable function is enabled

or disabled. This function is preferably enabled or disabled by the subscriber

in the setup mode, which is entered into by selecting the SETUP button 39.

During the setup mode, if the time scan disable function is enabled, the

subscriber can also enter a time which will be the time that the scanning

function is disabled. This information is transmitted to the controller 1 28 so

that the controller 1 28 can determine the length of time that the scanning

function should be disabled for.

In accordance with a preferred embodiment of the present invention, if

the subscriber attempts to enable the time scan disable function, the subscriber terminal 14, in step 464 asks the subscriber for a password. The

password is preferably set by the dispatcher from the dispatch station

through transmissions through the base station 2. The subscriber then

enters the password. If the password is incorrect, the microprocessor 50 in

the subscriber terminal 1 4 determines that the subscriber is not authorized to

enable the time scan disable function. If the password is correct, then the

microprocessor 50 transmits the instruction to the controller 1 28 to stop the

scanning function.

In step 466, the controller 1 28, when it receives the instruction from

the microprocessor 50, stops scanning the previously described list of

groups that the subscriber belongs to. Part of the instruction sent by the

microprocessor 50 is the disabling time selected by the subscriber. The

controller 1 28 keeps the scanning function disable for the selected length of

time. Then, after the passage of the selected period of time, the controller

1 28 causes the scanning function to begin again.

It is understood that changes may be made in the above description

without departing from the scope of the invention. It is accordingly intended

that all matter contained in the above description and in the drawings be

interpreted as illustrative rather than limiting.

Claims

WHAT IS CLAIMED IS:

1 . A method of controlling the scanning features of a mobile subscriber unit

used by a subscriber to a communication system, comprising the steps of:

storing a list of one or more groups to which the subscriber belongs in

the mobile subscriber unit;

assigning a priority to each of the groups in the list;

when a dispatch communication is received, determining the group to

which the dispatch is directed and the priority level of the group; and

if there is an existing dispatch communication being processed,

comparing the priority level of the existing dispatch communication and the

priority level of the recently received dispatch communication and enabling

the reception of the dispatch communication with the highest priority level.

2. The method of claim 1 , wherein there are two priority levels.

3. Apparatus for controlling the scanning features of a mobile subscriber

unit used by a subscriber to a communication system, comprising:

means for storing a list of one or more groups to which the subscriber

belongs in the mobile subscriber unit; and

means for deleting a selected one of the groups from the list.

4. The apparatus of claim 3, further comprising means for adding the

deleted group back to the list after a predetermined length of time.

5. The apparatus of claim 3, further comprising:

means for assigning a priority to each of the groups in the list; and

means for checking the priority of the group selected to be deleted

from the list and keeping the selected group on the list if the priority of the

selected group exceeds a predetermined priority level.

6. The apparatus of claim 5, further comprising:

means for informing the subscriber that the group selected for deletion

was a priority group that could not be deleted.

7. The apparatus of claim 3, further comprising:

means for asking the subscriber for a password before deleting the

selected group; and

means for verifying the entered password and for enabling the deletion

of the selected group only upon verification.

8. A method of controlling the scanning features of a mobile subscriber unit

used by a subscriber to a communication system, comprising the steps of:

storing a list of one or more groups to which the subscriber belongs in the mobile subscriber unit;

when a dispatch communication is received, determining the group to

which the dispatch is directed and informing the subscriber of the group;

disabling the step of determining the group under control of the

subscriber; and

after a selected period of time, enabling the step of determining the

group.

9. The method of claim 8, further comprising the step of:

the subscriber entering the period of time in which the step of

determining the group is disabled.

10. The method of claim 8, further comprising the steps of:

asking the subscriber for a password before disabling the step of

determining the group; and

verifying the entered password and disabling the step of determining

the group only upon verification.

1 1 . A method of processing dispatch communications in a radio terminal,

comprising the steps of:

storing information concerning the dispatch communications in a

memory in the radio terminal; and accessing the memory and displaying a listing of the information

concerning the dispatch communications.

1 2. The method of claim 1 1 , further comprising the steps of:

prior to the storing of information, receiving radio communications

which include dispatch communications with the radio terminal; and

determining which communications are dispatch communications.

1 3. The method of claim 1 1 , wherein the memory is accessed and the list

of the information concerning the dispatch communications is displayed

when a key on the radio terminal is activated.

14. The method of claim 1 1 , further comprising the steps of:

selecting one of the displays of information concerning dispatch

communications on the radio terminal; and

enabling a transmission from the radio terminal to the source of the

selected dispatch communication.

1 5. The method of claim 1 4, wherein the selection of the dispatch

communication is made by cursoring through the list of information

concerning dispatch communications.

1 6. The method of claim 1 1 , wherein the dispatch communications are

grouped into a plurality of groups and the group associated with each

dispatch communication is stored in memory.

1 7. The method of claim 1 6, wherein the display of information concerning

dispatch communications includes the group to which the dispatch

communication was made.

1 8. The method of claim 1 5, wherein the information concerning dispatch

communications within one group is stored in the memory only once during a

time period.

1 9. The method of claim 1 6, wherein the time period is one minute.

20. The method of claim 1 1 , further comprising the steps of:

time stamping the dispatches as they are received;

storing the time; and

displaying the time of reception of each dispatch communication.

21 . Apparatus for processing dispatch communications in a radio terminal,

comprising: means for storing information concerning the dispatch communications in a memory in the radio terminal;

means for accessing the memory and displaying a listing of the

information concerning the dispatch communications.

22. The apparatus of claim 21 , further comprising:

means for receiving radio communications which include dispatch

communications with the radio terminal; and

means for determining which communications are dispatch

communications.

23. The apparatus of claim 21 , further comprising a key that causes the

memory to be accessed and the listing of the information concerning the

dispatch communications to be displayed when activated.

24. The apparatus of claim 21 , further comprising:

means for selecting one of the displays of information concerning

dispatch communications on the radio terminal; and

means for enabling a transmission from the radio terminal to the

source of the selected dispatch communication.

25. The apparatus of claim 24, further comprising means for cursoring

through the list of information concerning dispatch communications to select a dispatch communication.

26. The apparatus of claim 21 , wherein the dispatch communications are

grouped into a plurality of groups and the group associated with each

dispatch communication is stored in memory.

27. The apparatus of claim 26, wherein the display of information

concerning dispatch communications includes the group to which the

dispatch communication was made.

28. The apparatus of claim 26, wherein the information concerning the

dispatch communications within one group is stored in the memory only

once during a time period.

29. The apparatus of claim 28, wherein the time period is one minute.

30. The apparatus of claim 21 , further comprising:

means for time stamping the dispatch communications as they are

received;

means for storing the time stamp; and

means for displaying the time of reception of each dispatch

communication.

31 . A method of processing dispatch communications in a subscriber's

radio terminal wherein the subscriber is a member of one or more groups of

subscribers, comprising the steps of:

storing the subscriber's current and previous active group in a

memory; and

displaying the subscriber's current and last active group on a display

of the radio terminal.

32. The method of claim 31 , further comprising the step of:

switching the status of the active group of the subscriber radio

terminal from the current active group to the previous active group.

33. Apparatus for processing dispatch communications in a subscriber's

radio terminal wherein the subscriber is a member of one or more groups of

subscribers, comprising:

means for storing the subscriber's current and previous active group in

a memory; and

means for displaying the subscriber's current and last active group on

a display of the radio terminal.

34. The apparatus of claim 33, further comprising:

means for switching the status of the active group of the subscriber radio terminal from the current active group to the previous active group.