U.S. patent application number 12/035197 was filed with the patent office on 2008-06-12 for method of implicit deassignment of resources.
This patent application is currently assigned to QUALCOMM Incorporated. Invention is credited to Avneesh Agrawal, David Jonathan Julian, Edward Harrison Teague.
Application Number | 20080137603 12/035197 |
Document ID | / |
Family ID | 36130021 |
Filed Date | 2008-06-12 |
United States Patent
Application |
20080137603 |
Kind Code |
A1 |
Teague; Edward Harrison ; et
al. |
June 12, 2008 |
METHOD OF IMPLICIT DEASSIGNMENT OF RESOURCES
Abstract
Accordingly, a method and apparatus are provided that use
implicit deassignment, instead of explicit deassignment, of
resources, such that a mobile terminal can interpret the assignment
of the resources to other channel terminals as an implied
deassignment of the resources. Thus, reducing the number of
assignment or the assignment between the base station and the
terminals.
Inventors: |
Teague; Edward Harrison;
(San Diego, CA) ; Agrawal; Avneesh; (San Diego,
CA) ; Julian; David Jonathan; (San Diego,
CA) |
Correspondence
Address: |
QUALCOMM INCORPORATED
5775 MOREHOUSE DR.
SAN DIEGO
CA
92121
US
|
Assignee: |
QUALCOMM Incorporated
San Diego
CA
|
Family ID: |
36130021 |
Appl. No.: |
12/035197 |
Filed: |
February 21, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11022507 |
Dec 22, 2004 |
|
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12035197 |
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Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04W 72/042 20130101;
H04W 76/30 20180201; H04W 72/04 20130101 |
Class at
Publication: |
370/329 |
International
Class: |
H04Q 7/00 20060101
H04Q007/00 |
Claims
1. A method of managing assignments of one or more communication
system resources, the method comprising acts of: transmitting an
assignment indication, said assignment indication comprising a
resource assignment that conflicts with a current assignment of the
resource.
2. The method as claimed in claim 1, further comprising act of
determining, prior to said act of transmitting, if said assignment
indication can be transmitted without transmitting a deassignment
indication for de-assigning assigned resources.
3. The method as claimed in claim 2, wherein said act of
determining comprises an act of determining if all the recipients
of said assignment indication are within a predetermined range.
4. The method as claimed in claim 1, wherein the said of
transmitting further comprising act of transmitting in accordance
with a Code Division Multiplex Access (CDMA) scheme.
5. The method as claimed in claim 1, wherein the said of
transmitting further comprising act of transmitting in accordance
with an Orthogonal Frequency Division Multiplex (OFDM) scheme.
6. The method as claimed in claim 1, wherein said act of
transmitting further comprising act of transmitting in accordance
with an Orthogonal Frequency Division Multiple Access (OFDMA)
scheme.
7. The method as claimed in claim 3, further comprising act of
determining required transmit power prior to said act of
transmitting said assignment indication.
8. A apparatus for managing assignments of one or more
communication system resources, the apparatus comprising: means for
transmitting an assignment indication, said assignment indication
comprising a resource assignment that conflicts with a current
assignment of the resource.
9. The apparatus as claimed in claim 8, further comprising means
for determining, prior to said means for transmitting, if said
assignment indication can be transmitted without transmitting a
deassignment indication for de-assigning assigned resources.
10. The apparatus as claimed in claim 9, wherein said means for
determining comprises means for determining if all the recipients
of said assignment indication are within a predetermined range.
11. The apparatus as claimed in claim 8, wherein said means for
transmitting comprises means for transmitting said assignment to
said first terminal and said new recipient terminal.
12. The apparatus as claimed in claim 8, wherein the said of
transmitting further comprising means for transmitting in
accordance with a Code Division Multiplex Access (CDMA) scheme.
13. The apparatus as claimed in claim 8, wherein the said of
transmitting further comprising means for transmitting in
accordance with an Orthogonal Frequency Division Multiplex (OFDM)
scheme.
14. The apparatus as claimed in claim 8, wherein said means for
transmitting further comprising means for transmitting in
accordance with an Orthogonal Frequency Division Multiple Access
(OFDMA) scheme.
15. The method as claimed in claim 10, further comprising means for
determining required transmit power prior to said act of
transmitting said assignment indication.
16. In a wireless communication, an apparatus comprising: an
electronic device, said electronic device configured to transmit an
assignment indication, said assignment indication comprising a
resource assignment that conflicts with a current assignment of the
resource.
17. The apparatus as claimed in claim 16, wherein said electronic
device further configured to determine, prior to transmitting said
assignment indication, if said assignment indication can be
transmitted without transmitting a deassignment indication for
de-assigning assigned resources.
18. The apparatus as claimed in claim 17, wherein said electronic
device further configured to determine if all the recipients of
said assignment indication are within a predetermined range.
19. The apparatus as claimed in claim 16, wherein said electronic
device further configured to transmit said assignment to said first
terminal and said new recipient terminal.
20. The apparatus as claimed in claim 16, wherein said electronic
device further configured to transmit in accordance with a Code
Division Multiplex Access (CDMA) scheme.
21. The apparatus as claimed in claim 16, wherein said electronic
device further configured to transmit in accordance with an
Orthogonal Frequency Division Multiplex (OFDM) scheme.
22. The apparatus as claimed in claim 16, wherein said electronic
device further configured to transmit in accordance with an
Orthogonal Frequency Division Multiple Access (OFDMA) scheme.
23. The apparatus as claimed in claim 18, wherein said electronic
device further configured to determine required transmit power
prior to said act of transmitting said assignment indication.
24. A machine-readable medium comprising instructions which, when
executed by a machine, cause the machine to perform operations
including: transmitting an assignment indication, said assignment
indication comprising a resource assignment that conflicts with a
current assignment of the resource.
25. The machine-readable medium of claim 24, further comprising
machine readable instruction to cause determining, if said
assignment indication can be transmitted without transmitting a
deassignment indication for de-assigning assigned resources.
26. The machine-readable medium as claimed in claim 25, wherein
said machine readable instruction to cause determining if all the
recipients of said assignment indication are within a predetermined
range.
27. The machine-readable medium as claimed in claim 24, wherein
said machine readable instruction to cause transmitting comprises
of transmitting said assignment to said first terminal and said new
recipient terminal.
28. A machine-readable medium of claim 24, further comprising
machine readable instruction to cause adjusting transmit power
prior to transmitting said assignment indication.
Description
REFERENCE TO CO-PENDING APPLICATIONS FOR PATENT
[0001] The present application is a divisional of pending U.S.
patent application Ser. No. 11/022,507 filed on Dec. 22, 2004 and
titled "Method of Implicit Deassignment of Resources". This
application is related to the following co-pending U.S. patent
applications: U.S. application Ser. No. 10/340,507, filed on Jan.
10, 2003 and U.S. application Ser. No. 10/726,944, filed Dec. 3,
2003, both assigned to the assignee hereof, and expressly
incorporated herein by reference.
FIELD OF INVENTION
[0002] The present invention relates generally to communication and
more specifically to techniques for deassigning communication
resources.
BACKGROUND
[0003] Wireless communication systems are widely deployed to
provide various types of communication such as voice, data, and so
on. These systems may be multiple-access systems capable of
supporting communication with multiple users by sharing the
available system resources (e.g., bandwidth and transmit power).
Examples of such multiple-access systems include code division
multiple access (CDMA) systems, time division multiple access
(TDMA) systems, frequency division multiple access (FDMA) systems,
and orthogonal frequency division multiple access (OFDMA) systems.
Typically, a wireless communication system comprises several base
stations (also referred to as access point), wherein each base
station communicates with the mobile station using a forward link
and each mobile station communicates with base station using a
reverse link.
[0004] Multiple access communication systems often employ a method
of assigning specific channel resources for use by one or more
terminals or access terminals (ATs). The resource may be a time
slot, spreading code, frequency band, etc. Both forward and reverse
link traffic channels may be assigned to terminals by messages
transmitted to the terminals via a shared or broadcast control
channel. Further, traffic channels may also be explicitly
deassigned by transmitting deassignment messages to terminals when
the network needs to use the resource for another user, or purpose.
Alternatively, traffic channels assignments may be explicitly
deassigned after each use of the channel (after each packet
transmission). Often, the resources required by this control
channel are high, and limitations on the control channel limit the
ability of the network to effectively manage the assignment of
traffic channels and to maximize the efficiency of the network.
[0005] In a typical communications system, such as OFDMA, the
certain resources are typically allocated to users on a temporary
basis. The base station provides indication to the users (one or
more access terminals in communication with the base station) have
explicit assignment and also provide an indication to the users of
explicit deassignment. Typically, a base station transmits an
assignment that is deassigned automatically after packet
transmission/reception. This removes the deassignment message
requirement, but would require an assignment for each channel use,
even if the user needs a "continuous" assignment, or
"semi-continuous" assignment. This requires several exchanges
between the user and the base station. Generally, the base station
transmits a deassignment message requesting the user to discontinue
the use of resources. Upon receiving and acknowledgement message,
the base station allocates those resources to a new user by
transmitting and assignment message. Deassignments are important to
prevent collisions of traffic and/or feedback channels, which can
severely limit network performance. However, transmitting
de-assignments and assignments increases assignment traffic and
lower efficiency in the system. In a system that uses a channel for
providing assignments to all users in the system, it is important
that the traffic on this channel be monitored efficiently. Thus,
using implicit assignments that allows the network to avoid sending
redundant information would be preferred.
[0006] Therefore, a method is needed to reduce the number of
assignment traffic between the base station and the user.
BRIEF SUMMARY OF THE INVENTION
[0007] Accordingly, a method and apparatus are provided that use
implicit deassignment, instead of explicit deassignment, of
resources, such that a mobile terminal can interpret the assignment
of the resources to other channel terminals as an implied
deassignment of the resources. Thus, reducing the number of
assignment or the assignment between the base station and the
terminals.
[0008] In an aspect, and first terminal processes an assignment and
determines if the assignment is for another terminal. If so, the
first terminal considers this event as a conflict in assignments.
In response to the identified conflict in assignment, the first
terminal considers this assignment of resources to another as
deassignment/de-allocation of resources and may further determine
if all the resources are deassigned/deallocated. If determined that
only a portion of resources are assigned to another terminal (e.g.
deassigned for first terminal), then the first terminal terminates
use of those resources that are assigned to the other terminal.
[0009] A more complete appreciation of all the advantages and scope
of the invention can be obtained from the accompanying drawings,
the description and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The features, nature, and advantages of the present
invention will become more apparent from the detailed description
set forth below when taken in conjunction with the drawings in
which like reference characters identify correspondingly throughout
and wherein:
[0011] FIG. 1 shows a diagram of a wireless multiple-access
communication system;
[0012] FIG. 2 illustrates a process for implicit deassignment of
communication resources;
[0013] FIG. 3 shows a process of handling assignment information
received on an assignment channel; and
[0014] FIG. 4 a block diagram of a communication system.
DETAILED DESCRIPTION
[0015] The word "exemplary" is used herein to mean "serving as an
example, instance, or illustration." Any embodiment or design
described herein as "exemplary" is not necessarily to be construed
as preferred or advantageous over other embodiments or designs. The
word "listening" is used herein to mean that a terminal is
receiving and processing data received on a given channel.
[0016] FIG. 1 shows a diagram of a wireless multiple-access
communication system 100 that employs multi-carrier modulation.
System 100 includes a number of access points, for example 110a and
110b that communicate with a number of access terminal 120a-120g.
For simplicity, only two access points 110a and 110b and only seven
access terminals 120a-120g are shown in FIG. 1. For purpose of
discussion, when referring to a single access terminal (AT) 120x is
used and when referring to a single access point (AP) 110x will be
used (access terminal 120x and access point 110x are described in
FIG. 2, infra).
[0017] An access point 110, is an electronic device configured to
communicate with one or more user access terminals and may also be
referred to as a base station, base terminal, fixed terminal, a
fixed station, base station controller, a controller, transmitter
or some other terminology. The access point, base terminal, and
base station are interchangeably used in the description below. The
access point 110 may be a general purpose computer, a standard
laptop, a fixed terminal, an electronic device configured to
transmit, receive and process data according to air interface
methods defined by an OFDMA, CDMA, GSM, WCDMA, etc., or an
electronic module comprising one or more computer chips controlled
by a controller or a processor for transmitting, receiving and
processing data according to air interface methods defined by an
OFDMA, CDMA, GSM, WCDMA, etc.
[0018] An access terminal 120, is an electronic device configured
to communicate with the access point via a communication link. The
access terminal may also be referred to as a terminal, a user
terminal, a remote station, a mobile station, a wireless
communication device, recipient terminal, or some other
terminology. The access terminal, mobile terminal, user terminal,
terminal are interchangeably used in the description below. Each
access terminal 120 may communicate with one or multiple access
points on the downlink and/or uplink at any given moment. The
downlink (i.e., forward link) refers to transmission from the
access point to the access terminal 120, and the uplink (i.e.,
reverse link) refers to transmission from the access terminal 120
to the access point. The access terminal 120 may be any standard
laptop, personal electronic organizer or assistant, a mobile phone,
cellular phone, an electronic device configured to transmit,
receive and process data according to air interface methods defined
by an OFDMA, CDMA, GSM, WCDMA, etc. system, or an electronic module
comprising one or more computer chips controlled by a controller or
a processor for transmitting, receiving and processing data
according to air interface methods defined by an OFDMA, CDMA, GSM,
WCDMA, etc. system.
[0019] A system controller 130 couples to the access points and may
further couple to other systems/networks (e.g., a packet data
network). System controller 130 provides coordination and control
for the access points coupled to it. Via the access points, system
controller 130 further controls the routing of data among the
terminals, and between the terminals and other users coupled to the
other systems/networks.
[0020] The techniques described herein for implicit deassignment of
one or more resources may be implemented in various wireless
multiple-access multi-carrier communication systems. For example,
system 100 may be an OFDMA, CDMA, GSM, WCDMA, etc. system that
utilizes data transmission.
[0021] For clarity, these techniques are described for an OFDMA
system that utilizes orthogonal frequency division multiplexing
(OFDM). In this system, a control channel is used assignments to
all terminals with the access point 110. In an embodiment, the
access point 110 determines if implicit deassignment may be
utilized to assign resources to a new terminal and at the same time
request deals terminal to deassign its resources. Under certain
conditions, such as terminal targeted for the new resources and the
terminal targeted for the old resources are within a predefined
range, the access point 110 will send only one assignment message
instead of and transmitting deassignment to one terminal and a
second message for assignment to another terminal.
[0022] In an embodiment, a terminal (for example first terminal)
demodulates assignment messages intended for all terminals. The
first terminal implicitly assumes a deassignment of channels
allocated to itself, whenever a in a conflict of assignment is
observed by the first terminal. Generally, a conflict arises if the
first terminal, having allocated channels, observes an assignment
of the allocated channels is observed as being assigned to another
terminal.
[0023] For example, if a shared channel is used for assignments, a
terminal will monitor this channel for conflicting assignments to
decide on deassignments. However, it could be common that only a
subset of users can successfully demodulate (for example, some
users out of range) a particular assignment message. In this case,
the network could choose to specifically control the transmission
of assignments (varying power, for example) such that terminals
that need to be deassigned channels can successfully demodulate the
relevant assignment messages that will cause implicit deassignment.
In other words, the network would "target" both the old and new
holder of the channel with an assignment.
[0024] In one embodiment, if a terminal does not observe any
deassignment messages or conflicting assignment messages, it
assumes that the existing channel assignments persist.
[0025] In one embodiment, if a first terminal observes an
assignment message to a second terminal that only partially
conflicts with the first terminal's channel assignment, the first
terminal may assume that the network only intends to deassign the
conflicting portion of the channel, and that the network intends
for the first terminal to retain the remaining resources as its
channel assignment.
[0026] In an embodiment, channels may be allocated according to a
channel tree, where code, time, or frequency resources can be
assigned in a variety of combinations defined by nodes on the tree.
In such a case, the tree provides constraints on the simultaneous
allocation of channels that can be used to indicate implicit
deassignment. If terminal detects a new assignment directed to
itself that conflicts with currently held assignments, the terminal
may either augment the total resources or expire old resources in
favor of the new assignment.
[0027] In an embodiment, the access point 110 monitors the location
of all the users and determines the power level that is required to
insure guarantee of receipt. That is, any message sent to the users
within a predetermined range will receive messages. Thus, for those
users within the range the ACK/NACK message exchange would not be
required. The access point 110 then send a new assignment, without
first sending a deassignment message to the targeted users. The
users then deassign or terminate use of any resources are in
conflict with the current assignment. In other words, automatically
interpret the assignment as deassignment of a resource if that
currently allocated resource is assigned to another user.
[0028] FIG. 2 illustrates a process 200, for implicit deassignment
of communication resources. The AP 110 is configured to execute
steps of the process 200 by utilizing at least one of various
components described in FIG. 2 for example, the controller 420, the
scheduler 430, the memory 422, the TX data processor 414, RX data
processor 434, etc. In an embodiment, AP 110 makes a determination
if one or more of the assigned resources should first be
de-assigned, by transmitting a de-assignment message using a
de-assignment of resources, or transmitting a new assignment
without sending any deassignment messages. This determination may
also be made by the controller 130 and thereafter requests the AP
110 to execute the process 200. At step 202, AP 110 determines
whether the access terminal 120 is within a range. The range may be
predetermined based statistical analysis, which shows that a
message to deassign one or more allocated resource without using
explicit deassignment. In an embodiment, a predetermined range is
measured by the maximum transmit power allowed by the system.
Generally, if the access terminal 120 is within the predetermined
range (for example within few hundred feet), then the access point
110 assumes that any message transmitted to the access terminal
120, will be received. If determined, at step 202, that the access
terminal 120 is outside the predetermined range, then at step 204,
the access point 110 performs an explicit deassingment.
[0029] However, if determined, at step 202, that the access
terminal 120 is within the predetermined range, then at step 206,
the access point 110 determines the required or appropriate
transmission power to insure that the access terminal 120 will
receive the new assignment information. At step 208, using
appropriate power, the access point 110 transmits a new assignment
of a resource to one or more access terminals.
[0030] The new assignment information is transmitted to all the
users within the predetermined range. Thus, if new the assignment
received by the access terminal (for example first access terminal)
indicates that the resource is now assigned to another access
terminal, then an assignment conflict occurs. This conflict
indicates to the recipient of the new assignment message, that one
or more of its allocated resources is now allocated to another
user, for example second access terminal. The access point 110
after a predetermine time begins transmitting information using new
resource assignment, thus the access point 110 implicitly
deassigned the resource.
[0031] FIG. 3 shows a process 300 of handling assignment
information received on an assignment channel, for example a Shared
Signaling Channel (SSCH). The access terminal 120 is configured to
execute steps of the process 300 by utilizing at least one of
various components described in FIG. 2 for example, the controller
460, the memory 462, the TX data processor 474, RX data processor
456, etc. At step 302, the access terminal 120 receives a new
assignment indication from the access point 110. At step 304, the
access terminal 120 determines if the new assignment conflicts with
current assignment. If at step 304, a conflict does occur, then
step 306 is executed. At step 306, the access terminal 120
determines if all the assigned resources are deassigned. If
determined that all the allocated resources are reassigned to
another user, then at step 308, the access terminal 120 will
terminate use of all allocated resources. Otherwise at step 310,
the access terminal 120 terminates only the conflicting resources
and continues to utilize the resources that were not conflicted by
the new assignment.
[0032] FIG. 4 shows a block diagram of an embodiment of an access
point 110x and two terminals 120x and 120y in multiple-access
multi-carrier communication system 100. At access point 110x, a
transmit (TX) data processor 414 receives traffic data (i.e.,
information bits) from a data source 412 and signaling and other
information from a controller 420 and a scheduler 430. For example,
controller 420 may provide power control (PC) commands that are
used to adjust the transmit power of the active terminals, and
scheduler 430 may provide assignments of carriers for the
terminals. These various types of data may be sent on different
transport channels. TX data processor 414 encodes and modulates the
received data using multi-carrier modulation (e.g., OFDM) to
provide modulated data (e.g., OFDM symbols). A transmitter unit
(TMTR) 416 then processes the modulated data to generate a downlink
modulated signal that is then transmitted from an antenna 418.
[0033] At each of terminals 120x and 120y, the transmitted and
modulated signal is received by an antenna 452 and provided to a
receiver unit (RCVR) 454. Receiver unit 454 processes and digitizes
the received signal to provide samples. A received (RX) data
processor 456 then demodulates and decodes the samples to provide
decoded data, which may include recovered traffic data, messages,
signaling, and so on. The traffic data may be provided to a data
sink 458, and the carrier assignment and PC commands sent for the
terminal are provided to a controller 460.
[0034] Controller 460 directs data transmission on the uplink using
the specific carriers that have been assigned to the terminal and
indicated in the received carrier assignment. Controller 460
further adjusts the transmit power used for the uplink
transmissions based on the received PC commands.
[0035] For each active terminal 120, a TX data processor 474
receives traffic data from a data source 472 and signaling and
other information from controller 460. The various types of data
are coded and modulated by TX data processor 474 using the assigned
carriers and further processed by a transmitter unit 476 to
generate an uplink modulated signal that is then transmitted from
antenna 452.
[0036] At access point 110x, the transmitted and modulated signals
from the terminals are received by antenna 418, processed by a
receiver unit 432, and demodulated and decoded by an RX data
processor 434. Receiver unit 432 may estimate the received signal
quality (e.g., the received signal-to-noise ratio (SNR)) for each
terminal and provide this information to controller 420. Controller
420 may then derive the PC commands for each terminal such that the
received signal quality for the terminal is maintained within an
acceptable range. RX data processor 434 provides the recovered
feedback information (e.g., the required transmit power) for each
terminal to controller 420 and scheduler 430.
[0037] Scheduler 430 uses the feedback information to perform a
number of functions such as (1) selecting a set of terminals for
data transmission on the reverse link and (2) assigning carriers to
the selected terminals. The carrier assignments for the scheduled
terminals are then transmitted on the forward link to these
terminals.
[0038] The techniques described herein may be implemented by
various means. For example, these techniques may be implemented in
hardware, software, or a combination thereof. For a hardware
implementation, the processing units (e.g., controllers 420 and
470, TX and RX processors 414 and 434, and so on) for these
techniques may be implemented within one or more application
specific integrated circuits (ASICs), digital signal processors
(DSPs), digital signal processing devices (DSPDs), programmable
logic devices (PLDs), field programmable gate arrays (FPGAs),
processors, controllers, micro-controllers, microprocessors, other
electronic units designed to perform the functions described
herein, or a combination thereof.
[0039] For a software implementation, the techniques described
herein may be implemented with modules (e.g., procedures,
functions, and so on) that perform the functions described herein.
The software codes may be stored in memory units (e.g., memory 422
in FIG. 4) and executed by processors (e.g., controllers 420). The
memory unit may be implemented within the processor or external to
the processor, in which case it can be communicatively coupled to
the processor via various means as is known in the art.
[0040] Headings are included herein for reference and to aid in
locating certain sections. These headings are not intended to limit
the scope of the concepts described therein under, and these
concepts may have applicability in other sections throughout the
entire specification.
[0041] The previous description of the disclosed embodiments is
provided to enable any person skilled in the art to make or use the
present invention. Various modifications to these embodiments will
be readily apparent to those skilled in the art, and the generic
principles defined herein may be applied to other embodiments
without departing from the spirit or scope of the invention. Thus,
the present invention is not intended to be limited to the
embodiments shown herein but is to be accorded the widest scope
consistent with the principles and novel features disclosed
herein.
* * * * *