Subject: [NEXTEL-1] Method and apparatus for providing a dispatch patch service in a CDMA communication system

From: Marcel <[email-masked]>
Date: Wed, 22 Jan 2003 04:00:43 -0500

Panchal, Rajendra A. ;   et al.
                                                                              September
19, 2002

Method and apparatus for providing a dispatch patch service in a CDMA communication system

                                             Abstract

In general, the present invention discloses a method and an apparatus that provide a
dispatch patch service in a CDMA
communication system (100). A communication unit (103) involved in a dispatch call
requests a base site (101) to patch a
patch target (105), either a dispatch group or an individual, into the present call. By
providing the CDMA long-code mask
being used for the present call to the patch target and the dispatch identifier of the
patch target to at least the communication
unit, a new CDMA long-code mask can be generated and used for the dispatch call going
forward.

 Inventors:
              Panchal, Rajendra A.; (Algonquin, IL) ; Rozenstrauch, Alexander; (Buffalo
Grove, IL)

 Assignee Name

              MOTOROLA, INC

Claims

What is claimed is:

1. A method for a base site to provide a dispatch patch service to a communication unit in
a CDMA communication system,
the method comprising the steps of: encoding dispatch communication for a dispatch call
using a first CDMA long-code mask;
receiving a request to patch a dispatch target into the dispatch call from the
communication unit, wherein, prior to the step of
receiving, the dispatch call does not involve the dispatch target and the first CDMA
long-code mask is used for encoding
dispatch communication for the dispatch call; and transmitting a channel assignment to the
dispatch target that indicates the first
CDMA long-code mask.

2. The method of claim 1 further comprising the steps of: transmitting CDMA long-code mask
update information to the
communication unit; generating a second CDMA long-code mask using the first CDMA long-code
mask and a dispatch
identifier of the dispatch target; and encoding dispatch communication for the dispatch
call using the second CDMA long-code
mask.

3. The method of claim 1 further comprising the step of transmitting a dispatch page to
the dispatch target.

4. The method of claim 2 wherein the dispatch call is a group dispatch call.

5. The method of claim 2 wherein the dispatch call is an individual dispatch call.

6. The method of claim 2 wherein the dispatch target is a dispatch group.

7. The method of claim 2 wherein the dispatch target is a dispatch individual.

8. The method of claim 2 wherein the dispatch identifier of the dispatch target comprises
a dispatch group identifier of the
dispatch group associated with the dispatch target.

9. The method of claim 2 wherein the dispatch identifier of the dispatch target comprises
a dispatch individual identifier of the
dispatch target.

10. The method of claim 2 wherein the channel assignment indicates a traffic channel
associated with the dispatch call prior to
the step of receiving.

11. A method for a communication unit to invoke a dispatch patch service from a base site
in a CDMA communication system,
the method comprising the steps of: decoding, by the communication unit, dispatch
communication for a dispatch call using a
CDMA long-code mask; transmitting, by the communication unit, a request to patch a
dispatch target into the dispatch call,
wherein the dispatch call does not involve the dispatch target prior to the step of
transmitting; receiving, by the communication
unit, CDMA long-code mask update information; and decoding, by the communication unit
subsequent to the step of
transmitting, dispatch communication for the dispatch call using an updated CDMA long-code
mask, wherein the dispatch call
involves at least the communication unit and the dispatch target.

12. The method of claims 11 wherein the CDMA long-code mask update information is the
updated CDMA long-code mask.

13. The method of claim 11 further comprising the step of updating the CDMA long-code mask
using the CDMA long-code
mask update information to produce the updated CDMA long-code mask.

14. The method of claim 13 wherein the CDMA long-code mask update information comprises a
dispatch identifier of the
dispatch target.

15. The method of claim 11 further comprising the step of receiving, by the communication
unit, information about the dispatch
target.

16. A method for a communication unit to be patched into a dispatch call in a CDMA
communication system, the method
comprising the steps of: receiving, by the communication unit, a dispatch page for the
dispatch call; receiving, by the
communication unit, a channel assignment that indicates a first CDMA long-code mask used
for the dispatch call prior to the
step of receiving the dispatch page; generating, by the communication unit, a second CDMA
long-code mask using the first
CDMA long-code mask and a dispatch identifier of the communication unit; and decoding, by
the communication unit, dispatch
communication for the dispatch call using the second CDMA long-code mask.

17. The method of claim 16 wherein the dispatch identifier of the communication unit
comprises a dispatch group identifier of
the dispatch group associated with the communication unit.

18. The method of claim 16 wherein the dispatch identifier of the communication unit
comprises a dispatch individual identifier
of the communication unit.

19. A base site comprising: a processor capable of encoding dispatch communication for a
dispatch call using a first CDMA
long-code mask; a receiver capable of receiving a request to patch a dispatch target into
the dispatch call from a
communication unit, wherein, prior to the receiver receiving the request, the dispatch
call does not involve the dispatch target
and the first CDMA long-code mask is used for encoding dispatch communication for the
dispatch call; and a transmitter
capable of transmitting, when instructed to transmit by the processor, a channel
assignment to the dispatch target that indicates
the first CDMA long-code mask.

20. The base site of claim 19 wherein the transmitter is further capable of transmitting
CDMA long-code mask update
information to the communication unit when instructed to by the processor and wherein the
processor is further capable of
generating a second CDMA long-code mask using the first CDMA long-code mask and a dispatch
identifier of the dispatch
target and capable of encoding dispatch communication for the dispatch call using the
second CDMA long-code mask.

21. A communication unit comprising: a processor capable of decoding dispatch
communication for a dispatch call using a
CDMA long-code mask, capable of instructing the transmitter to transmit a request to patch
a dispatch target into the dispatch
call, wherein the dispatch call does not involve the dispatch target prior to instructing
the transmitter to transmit the request to
patch, and capable of decoding, subsequent to instructing the transmitter to transmit the
request to patch, dispatch
communication for the dispatch call using an updated CDMA long-code mask for the dispatch
call, wherein the dispatch call
involves at least the communication unit and the dispatch target; a transmitter capable of
transmitting the request to patch; and a
receiver capable of receiving CDMA long-code mask update information used to generate the
updated CDMA long-code
mask.

22. A communication unit comprising: a receiver capable of receiving a dispatch page for a
dispatch call and a channel
assignment that indicates a first CDMA long-code mask used for the dispatch call; and a
processor capable of generating a
second CDMA long-code mask using the first CDMA long-code mask and a dispatch identifier
of the communication unit and
capable of decoding dispatch communication for the dispatch call using the second CDMA
long-code mask.

                                           Description

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is related to a co-pending application, "METHOD AND APPARATUS FOR
PROVIDING
DISPATCH SERVICE IN A CDMA COMMUNICATION SYSTEM", Ser. No. 09/443,538, filed on Nov. 19,
1999,
assigned to the assignee of the present application, which prior application is hereby
incorporated by reference verbatim, with
the same effect as though the prior application were fully and completely set forth
herein. This application is also related to a
co-pending application, "METHOD AND APPARATUS FOR PROVIDING DISPATCH SCAN IN A CDMA
COMMMUNICATION SYSTEM", Ser. No. 09/757,335, filed on Jan. 10, 2001 and assigned to the
assignee of the present
application.

Field of the Invention

[0002] The present invention relates generally to the field of wireless communications
and, more particularly, to a dispatch
patch service on code division multiple access (CDMA) communication systems.

BACKGROUND OF THE INVENTION

[0003] Communication systems today, such as Motorola's "iDEN" system, provide users with
so-called dispatch services.
Unlike the interconnect services provided by today's cellular systems, dispatch services
have been traditionally provided by
two-way radio systems. Such services allow a user to communicate in ways that are
difficult or costly using today's cellular
systems. The dispatch group call service, for example, enables a user to communicate with
a group of people simultaneously
and instantaneously, usually just by depressing a push-to-talk (PTT) button. Using a
cellular system, such a call could not occur
instantaneously since either telephone numbers would need to be dialed for a three-way
call or arrangements would need to be
made to setup a conference call.

[0004] Likewise, the dispatch individual call service enables a user to communicate with
another user quickly and
spontaneously. This feature is ideal for two people who are working together but are
unable to speak with one another directly
such as two people working in concert but in different parts of a building. Where a
wireless telephone call is more appropriate
for a conversation, short messages between two people as they work are better facilitated
by the dispatch individual call
service.

[0005] Occasionally however, two or more users already involved in dispatch communication
need to include another user in
their call. Private radio systems today allow a dispatcher, for example, to patch dispatch
groups together. However, today's
CDMA systems neither provide dispatch service nor a dispatch patch service that would
enable a user involved in a dispatch
call to patch another user into the existing call. The co-pending application "METHOD AND
APPARATUS FOR
PROVIDING DISPATCH SERVICE IN A CDMA COMMUNICATION SYSTEM" discloses modifications to the
IS-95
CDMA standard enabling CDMA dispatch service. However, this co-pending application does
not disclose a CDMA
embodiment that enables the dispatch patch service. Therefore, a need exists for an
apparatus and method for providing a
dispatch patch service in a CDMA communication system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a block diagram depiction of a CDMA communication system in accordance
with a preferred embodiment of
the present invention.

[0007] FIG. 2 is a logic flow diagram of steps executed by a base site in accordance with
a preferred embodiment of the
present invention.

[0008] FIG. 3 is a logic flow diagram of steps executed by a communication unit to invoke
a dispatch patch service in
accordance with a preferred embodiment of the present invention.

[0009] FIG. 4 is a logic flow diagram of steps executed by a communication unit being
patched into a dispatch call in
accordance with a preferred embodiment of the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

[0010] In general, the present invention discloses a method and an apparatus that provide
a dispatch patch service in a CDMA
communication system. A communication unit involved in a dispatch call requests a base
site to patch a patch target, either a
dispatch group or an individual, into the present call. By providing the CDMA long-code
mask being used for the present call
to the patch target and the dispatch identifier of the patch target to at least the
communication unit, a new CDMA long-code
mask can be generated and used for the dispatch call going forward.

[0011] The present invention encompasses a method for providing a dispatch patch service
to a communication unit in a
CDMA communication system. This method comprises encoding dispatch communication for a
dispatch call using a first
CDMA long-code mask and receiving a request to patch a dispatch target into the dispatch
call from the communication unit,
where prior to the step of receiving the dispatch call does not involve the dispatch
target and the first CDMA long-code mask
is used for encoding dispatch communication for the dispatch call. This method also
comprises transmitting a channel
assignment to the dispatch target that indicates the first CDMA long-code mask.

[0012] The present invention further encompasses a method to invoke a dispatch patch
service from a base site in a CDMA
communication system. In this method, a communication unit decodes dispatch communication
for a dispatch call using a
CDMA long-code mask and transmits a request to patch a dispatch target into the dispatch
call, where the dispatch call does
not involve the dispatch target prior to transmitting. The communication unit also
receives CDMA long-code mask update
information and decodes dispatch communication for the dispatch call using an updated CDMA
long-code mask, wherein the
dispatch call involves at least the communication unit and the dispatch target.

[0013] Additionally, the present invention encompasses a method for a communication unit
to be patched into a dispatch call in
a CDMA communication system. In this method, the communication unit receives a dispatch
page for the dispatch call and a
channel assignment that indicates a first CDMA long-code mask used for the dispatch call.
The communication unit also
generates a second CDMA long-code mask using the first CDMA long-code mask and a dispatch
identifier of the
communication unit and decodes dispatch communication for the dispatch call using the
second CDMA long-code mask.

[0014] The present invention also encompasses an apparatus for a base site. This base site
comprises a processor capable of
encoding dispatch communication for a dispatch call using a first CDMA long-code mask and
a a receiver capable of receiving
a request to patch a dispatch target into the dispatch call from a communication unit,
where prior to the receiver receiving the
request, the dispatch call does not involve the dispatch target and the first CDMA
long-code mask is used for encoding
dispatch communication for the dispatch call. The base site also comprises a transmitter
capable of transmitting, when instructed
to transmit by the processor, a channel assignment to the dispatch target that indicates
the first CDMA long-code mask.

[0015] The present invention also encompasses an apparatus for a communication unit. This
communication unit comprises a
processor capable of decoding dispatch communication for a dispatch call using a CDMA
long-code mask, capable of
instructing the transmitter to transmit a request to patch a dispatch target into the
dispatch call, and capable of decoding,
subsequent to instructing the transmitter to transmit the request to patch, dispatch
communication for the dispatch call using an
updated CDMA long-code mask for the dispatch call. This communication unit also comprises
a transmitter capable of
transmitting the request to patch and a receiver capable of receiving CDMA long-code mask
update information used to
generate the updated CDMA long-code mask.

[0016] Furthermore, the present invention encompasses another apparatus for a
communication unit. This communication unit
comprises a receiver capable of receiving a dispatch page for a dispatch call and a
channel assignment that indicates a first
CDMA long-code mask used for the dispatch call. This communication unit also comprises a
processor capable of generating a
second CDMA long-code mask using the first CDMA long-code mask and a dispatch identifier
of the communication unit and
capable of decoding dispatch communication for the dispatch call using the second CDMA
long-code mask.

[0017] The present invention can be more fully understood with reference to FIGS. 1-4.
FIG. 1 is a block diagram depiction of
a CDMA communication system 100 in accordance with a preferred embodiment of the present
invention. Preferably, the
CDMA communication system 100 is a system in accordance with the well-known
Telecommunications Industry
Association/Electronic Industries Association Standard 95 (TIA/EIA IS-95-B) modified as
described below to implement the
present invention and modified as described in co-pending application "METHOD AND
APPARATUS FOR PROVIDING
DISPATCH SERVICE IN A CDMA COMMUNICATION SYSTEM" to provide dispatch group and individual
service.
CDMA communication system 100 could alternatively be based upon the TIA/EIA IS-2000 (CDMA
2000) standard rather
than IS-95.

[0018] CDMA communication system 100 comprises fixed network equipment and mobile
communication units. The fixed
network equipment includes a base site 101 that is preferably networked to other base
sites, controllers, and switches, all part
of the fixed network equipment of system 100 and all well known to those skilled in the
art. For simplicity, only base site 101 of
the fixed network equipment is shown in FIG. 1. Again for simplicity, only three of what
could be thousands of mobile
communication units are shown in FIG. 1. Communication units 103-105 each preferably
comprise CDMA-capable wireless
phones. They communicate with base site 101 via a CDMA air interface that comprises
coded-channel communication
resources 115 and 116. In an alternative embodiment, however, the communication units
could comprise any communication
device capable of communicating via a CDMA air interface.

[0019] Each of the communication units 103-105 comprises a common set of elements, a
transmitter, a receiver, and a
processor. In particular, processor 110 and processor 113, each typically comprise one or
more processing devices (e.g.,
microprocessors, digital signal processors, etc.) and memory devices, are coupled to
transmitter 109 and transmitter 112,
respectively, and coupled to receiver 111 and receiver 114, respectively. Each of these
elements is well-known in the art. In
the preferred embodiment, under the control of software algorithms stored in the memory
devices of processor 110 and in
cooperation with the other elements shown, the processor 110 performs those tasks required
for operation of communication
unit 105, including the method described relative to FIG. 4. Similarly, in the preferred
embodiment, under the control of
software algorithms stored in the memory devices of processor 113 and in cooperation with
the other elements shown, the
processor 113 performs those tasks required for operation of the communication unit 103,
including the method described
relative to FIG. 3.

[0020] Base site 101 also comprises elements well-known in the art, a transmitter 106, a
receiver 108, and a processor 107.
Coupled to transmitter 106 and receiver 108, processor 107 preferably comprises memory
devices and processing devices
such as a microprocessor and digital signal processor. In the preferred embodiment, under
the control of software algorithms
stored in the memory devices of processor 107 and in cooperation with the other elements
shown, the processor 107 performs
those tasks required for operation of the base site, including the method described
relative to FIG. 2.

[0021] Operation of the preferred CDMA communication system 100, in accordance with the
present invention, occurs
substantially as follows. Communication units 103 and 104 are, for the purpose of
illustration, logically arranged into a dispatch
group (or talkgroup) 120 that is involved in a dispatch group call supported by base site
101. Preferably, processor 107 is
encoding dispatch communication for the dispatch call using a first CDMA long-code mask,
and transmitter 106 is transmitting
this encoded communication to the communication units 103 and 104 via coded-channel
communication resource 116.
Communication units 103 and 104, but not communication unit 105, decode this dispatch
communication using the first CDMA
long-code mask. To simplify illustration, the dispatch communication is not originated by
any of the communication units or base
site of FIG. 1. Instead, it is assumed that another member of dispatch group 120 at
another base site (not shown) is originating
the dispatch communication, i.e., it is the member talking to the rest of the group.

[0022] Wanting to patch communication unit 105 into the present dispatch call, the user of
communication unit 103 makes the
required keystrokes to communication unit 103. Processor 113 preferably generates a
modified IS-95/CDMA 2000 ORDER
message containing a patch_new_target value for the ORDER QUALIFICATION CODE and the
dispatch identifier of
communication unit 105 in the ORDER SPECIAL FIELDS. Processor 113 then instructs
transmitter 112 to transmit this
request to patch dispatch target 105 into the dispatch call. Receiver 108 receives the
request, and processor 107 preferably
generates a modified IS-95/CDMA 2000 GENERAL PAGE message in which the PAGE CLASS field
contains "11", the
SPECIAL SERVICE flag is set, the SERVICE OPTION field contains a value indicating
dispatch, and the mobile subscriber
identifier contains the dispatch identifier of communication unit 105. This page message
is transmitted by base site 101 and
received by receiver 111. In the preferred embodiment, communication unit 105 responds
with an enhanced PAGE
RESPONSE message in which the SPECIAL SERVICE flag is set and the SERVICE OPTION field
contains a value
indicating dispatch.

[0023] Processor 107 generates a modified IS-95/CDMA 2000 CHANNEL ASSIGNMENT and instructs
transmitter 106 to
transmit it to communication unit 105. Received by receiver 111, this modified CHANNEL
ASSIGNMENT preferably
indicates both the traffic channel and the first CDMA long-code mask being used for the
dispatch call. Processor 107 also
preferably generates a modified IS-95/CDMA 2000 ORDER message in which the ORDER field
contains the
long_code_transition value, the ORDQ field contains the dispatch_mask_switchover value,
the TARGET_ID field contains the
dispatch target identifier for communication unit 105, and the TARGET_NAME field contains
any alias information by which
communication unit 105 is identified to the other call members. Processor 107 instructs
transmitter 106 to transmit the modified
CHANNEL. ASSIGNMENT and modified ORDER message, each with its CDMA long-code mask update
information, to
communication unit 105 (the CHANNEL ASSIGNMENT) and communication units 103 and 104 (the
ORDER message).

[0024] Thus, the receivers of communication units 103-105 receive CDMA long-code mask
update information by one of two
messages, and thereby, each communication unit has the first CDMA long-code mask and the
dispatch identifier of
communication unit 105. The processors of communication units 103-105 and base site 101
generate a second CDMA
long-code mask using the first CDMA long-code mask and the dispatch identifier of
communication unit 105. Preferably,
communication devices 101, and 103-105 generate this second CDMA long-code mask using a
pre-defined algorithm known
to each, such as simply exclusive ORing the first CDMA long-code mask and the dispatch
identifier of communication unit 105.
Processor 107 now begins to encode dispatch communication for the continuing dispatch call
using this second CDMA
long-code mask. Finally, communication units 103-105 receive the encoded dispatch
communication via coded-channel
communication resource 115 and decode it using the second CDMA long-code mask. Thus, this
preferred embodiment
effectively patches communication unit 105 into the dispatch call already in progress.

[0025] Although the description above describes patching an individual communication unit
into a group dispatch call. The
present invention is not limited to such a scenario. Rather, the dispatch call could have
been a dispatch individual call between
communication units 103 and 104 or the dispatch target (communication unit 105 above)
could have been an entire dispatch
group that was being patched into the existing dispatch call. In other words, the dispatch
identifier of the dispatch target that is
being patched can identify either a dispatch group or a dispatch individual; the present
invention encompasses both.

[0026] Also, the present invention does not limit the number of different dispatch targets
that can be patched into an existing
dispatch call. For example, a dispatch individual may be patched first, followed by a
dispatch group second, followed by a
dispatch individual third, and so on. Each time a new dispatch target is patched into the
call, the new long-code mask is
generated based on the mask being used and the dispatch identifier of the new dispatch
target. Thus, the present invention
enables a flexible dispatch patch service for a CDMA communication system, and the
preferred embodiment disclosed
provides the service with minimal deviations from the IS-95 and CDMA 2000 standards.

[0027] FIG. 2 is a logic flow diagram 200 of steps executed by a base site in accordance
with a preferred embodiment of the
present invention. The logic flow begins (202) with a dispatch call already in progress,
and the base site encoding (204)
dispatch communication for the dispatch call using a first CDMA long-code mask. The
dispatch call may be either a group
dispatch call between the members of a dispatch group or an individual dispatch call
between two dispatch individuals.

[0028] Sometime during the call, the base site receives (206), from a communication unit
in the call, a request to patch a
dispatch target into the call. This dispatch target may be either a dispatch group or a
dispatch individual that is not presently part
of the dispatch call. The base site preferably transmits a dispatch page (208) and a
channel assignment (210) to the dispatch
target. The preferred channel assignment indicates both the first CDMA long-code mask and
the traffic channel presently being
used by the dispatch call. To the requesting communication unit and the other units
involved in the dispatch call, the base site
preferably transmits (212) CDMA long-code mask update information, thereby ordering the
communication units to update the
CDMA long-code mask that they are using for this call.

[0029] In the preferred embodiment, the base site then generates (214) a second CDMA
long-code mask using the first
CDMA long-code mask and the dispatch identifier of the dispatch target. The structure of a
preferred dispatch identifier is
described in the co-pending application, "METHOD AND APPARATUS FOR PROVIDING DISPATCH
SERVICE IN A
CDMA COMMUNICATION SYSTEM." In general, the dispatch identifier of the dispatch target may
contain either or both a
dispatch group identifier or a dispatch individual identifier of the dispatch target.
Finally, the base site preferably begins
encoding (216) dispatch communication for the dispatch call using the second CDMA
long-code mask, and the logic flow ends
(218).

[0030] FIG. 3 is a logic flow diagram 300 of steps executed by a communication unit to
invoke a dispatch patch service in
accordance with a preferred embodiment of the present invention. The logic flow begins
(302) with a dispatch call already in
progress and the communication unit decoding (304) dispatch communication for the dispatch
call using a CDMA long-code
mask. The communication unit transmits (306) a request to patch a dispatch target, not yet
involved in the dispatch call, into the
dispatch call. The communication unit then receives (308) CDMA long-code mask update
information. Preferably, this update
information contains the dispatch identifier of the dispatch target and other information
about the dispatch target such as alias
information.

[0031] In the preferred embodiment, the communication unit then updates (310) the CDMA
long-code mask, using the
CDMA long-code mask update information, to produce an updated CDMA long-code mask. This
update preferably involves
computing a new long-code mask using the dispatch identifier of the dispatch target and
the CDMA long-code mask being
used for the call. Alternatively, however, the CDMA long-code mask update information may
contain the updated CDMA
long-code mask itself and, thus, no computing would be necessary. However, because
transmitting the new mask directly is
less secure than independently computing it, the computation is preferable. Finally, the
communication unit begins decoding
(312) dispatch communication for the dispatch call, which now includes the dispatch
target, using the updated CDMA
long-code mask, and the logic flow ends (314).

[0032] FIG. 4 is a logic flow diagram 400 of steps executed by a communication unit being
patched into a dispatch call in
accordance with a preferred embodiment of the present invention. The logic flow begins
(402) when this communication unit
receives (404) a dispatch page for the dispatch call already in progress. The
communication unit then receives (406) a channel
assignment that indicates a first CDMA long-code mask. This is the long-code mask that the
dispatch call was using when
communication unit received the dispatch page. The communication unit then generates a
second CDMA long-code mask using
the first CDMA long-code mask and its dispatch identifier. Finally, the communication unit
joins the dispatch call in-progress by
beginning to decode dispatch communication for the call using the second CDMA long-code
mask, and the logic flow ends
(412).

[0033] The descriptions of the invention, the specific details, and the drawings mentioned
above, are not meant to limit the
scope of the present invention. It is the intent of the inventors that various
modifications can be made to the present invention
without varying from the spirit and scope of the invention, and it is intended that all
such modifications come within the scope of
the following claims and their equivalents.

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