U.S. patent number RE44,553 [Application Number 13/548,917] was granted by the patent office on 2013-10-22 for apparatus and an associated method for facilitating communications in a radio communication system that provides for data communications at multiple data rates.
This patent grant is currently assigned to Nokia Corporation. The grantee listed for this patent is Zhouyue Pi, Zhigang Rong. Invention is credited to Zhouyue Pi, Zhigang Rong.
United States Patent |
RE44,553 |
Pi , et al. |
October 22, 2013 |
Apparatus and an associated method for facilitating communications
in a radio communication system that provides for data
communications at multiple data rates
Abstract
Apparatus, and an associated method, for facilitating operation
of a radio communication system that provides for multi rate data
communications, such as a CDMA 2000 system that provides for
1xEV-DV communication services. A supplemental pilot, or control,
signal generator embodied at a mobile station generates a
supplemental pilot, or control, signal that is sent on a newly
defined supplemental pilot, or control, channel. As the data rates
of data communicated upon a reverse supplemental channel changes,
corresponding changes are made to the power level of the reverse
supplemental pilot, or control, signal.
Inventors: |
Pi; Zhouyue (San Diego, CA),
Rong; Zhigang (San Diego, CA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Pi; Zhouyue
Rong; Zhigang |
San Diego
San Diego |
CA
CA |
US
US |
|
|
Assignee: |
Nokia Corporation (Espoo,
FI)
|
Family
ID: |
29739918 |
Appl.
No.: |
13/548,917 |
Filed: |
July 13, 2012 |
PCT
Filed: |
June 05, 2003 |
PCT No.: |
PCT/US03/17625 |
371(c)(1),(2),(4) Date: |
October 28, 2004 |
PCT
Pub. No.: |
WO03/105381 |
PCT
Pub. Date: |
December 18, 2003 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
60386819 |
Jun 7, 2002 |
|
|
|
|
60386906 |
Jun 7, 2002 |
|
|
|
Reissue of: |
10512850 |
Jun 5, 2003 |
7660277 |
Feb 9, 2010 |
|
|
Current U.S.
Class: |
370/335; 370/329;
455/522; 370/342; 370/318; 370/437 |
Current CPC
Class: |
H04W
52/26 (20130101); H04W 36/16 (20130101); H04W
52/12 (20130101); H04W 52/267 (20130101); H04W
52/0229 (20130101); H04W 52/16 (20130101); H04W
52/0216 (20130101); Y02D 30/70 (20200801); H04W
28/22 (20130101) |
Current International
Class: |
H04B
7/26 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
0977371 |
|
Feb 2000 |
|
EP |
|
1067704 |
|
Jan 2001 |
|
EP |
|
1067704 |
|
Oct 2001 |
|
EP |
|
0126246 |
|
Apr 2001 |
|
WO |
|
WO 01/26246 |
|
Apr 2001 |
|
WO |
|
2004098097 |
|
Nov 2004 |
|
WO |
|
Other References
Notification of the 2nd Office Action for CN201110065764.5 dated
Oct. 31, 2012, with English translation. cited by applicant .
Examination Report in EP08158310.6 dated Feb. 15, 2013. cited by
applicant .
International Search Report for PCT/US03/17625 dated Nov. 13, 2003.
cited by applicant .
European Search Report in related European Application No.
08158312, dated Dec. 8, 2010, pp. 1-5. cited by applicant .
European Search Report for EP08158310 dated Feb. 8, 2010, pp. 1-2.
cited by applicant .
Office Action in related Chinese Application No. 03813219.2 dated
Oct. 9, 2010, pp. 1-6. cited by applicant .
Notification of the First Office Action in CN201110065764.5 dated
Feb. 13, 2012, with English translation. cited by applicant .
European Search Report for EP Application No. 03 73 1552. cited by
applicant.
|
Primary Examiner: Mills; Donald L
Attorney, Agent or Firm: Banner & Witcoff, Ltd.
Parent Case Text
.Iadd.CROSS-REFERENCE TO RELATED APPLICATIONS .Iaddend.
.Iadd.The present application is a U.S. national stage under 35
U.S.C. 371 of PCT/US03/17625, filed Jun. 5, 2003, which claims the
benefit of U.S. Ser. No. 60/386,819, filed Jun. 7, 2002, and U.S.
Ser. No. 60/386,906, filed Jun. 7, 2002. .Iaddend.
Claims
We claimed:
1. A method comprising: transmitting from a radio communication
system a primary pilot signal corresponding to a data channel;
detecting when data communicated upon the data channel exceeds a
predetermined target level data rate; and generating a supplemental
pilot signal increasing total pilots power in response to the data
communicated upon the data channel exceeding the predetermined
target level data rate.
2. The method of claim 1 further comprising the operation of
terminating the supplemental pilot signal in response to the data
communicated upon the data channel falling below the target level
data rate.
3. The method of claim 1 wherein a communication station comprises
a mobile station operable in the radio communication system and
wherein the supplemental pilot signal is generated concurrent with
communication of the data on the data channel.
4. The method of claim 1 wherein a communication station comprises
a mobile station operable in the radio communication system,
wherein the data communicated by the mobile station is communicated
upon a reverse-link data channel defined in the radio communication
system, and wherein the radio communication system defines a
reverse link pilot channel, and the supplemental pilot signal, when
generated during said operation of generating, is generated upon
the reverse link pilot channel.
5. The method of claim 4 wherein the radio communication system
defines a first reverse link pilot channel and a second reverse
link pilot channel, the second reverse link pilot channel
supplemental to the first reverse link pilot channel, and wherein
the supplemental pilot signal, when generated during said operation
of generating, is generated upon the second reverse link pilot
channel.
6. The method of claim 1 wherein the supplemental pilot signal,
when generated during said operation of generating, is generated
for a selected time period subsequent to detection, during said
operation of detecting, that the data communicated upon the data
channel exceeds the target level data rate.
7. An apparatus comprising: a pilot signal generator configured to
generate a second pilot signal providing extra power supplementing
a first pilot signal that corresponds to a reverse link data
channel in a radio communication system, the second pilot signal
generated by said pilot signal generator to supplement signal
energy of the first pilot signal responsive to data communicated
upon the reverse link data channel exhibiting a communication
parameter that exceeds a selected target level.
8. The apparatus of claim 7 wherein the communication parameter is
a data rate of the reverse link data channel.
9. The method of claim 1 wherein a communication station sends a
fundamental signal during operation of the communication station
and wherein the supplemental pilot signal, when generated during
said operation of generating, is supplemental to the fundamental
signal.
10. The apparatus of claim 7, wherein the pilot signal generator is
further configured to 1) maintain the first and second pilot
signals for a first time period, and 2) remove the second pilot
signal and increase a power level of the first pilot signal to
compensate for power lost from the removal of the second pilot
signal for a second time period following the first time
period.
11. The apparatus of claim 7, wherein the pilot signal generator is
configured to dynamically adjust a total pilot signal power level
in the first and second pilot signals corresponding to changes in a
data transmission rate of the reverse data channel.
Description
The present invention relates generally to a manner by which to
facilitate communications in a radio communication system that
provides for data communications at multiple data rates, such as a
CDMA 2000 cellular communication system that provides for 1xEV-DV
data communication services. More particularly, the present
invention relates to apparatus, and an associated method, that
provides a pilot, or other control, signal, of levels related to
the data rates at which the data is communicated. When the data
rate at which data is communicated is changed, the levels at which
the pilot, or other control, signal is generated correspondingly
changes.
Because the pilot, or other control, signal is of a level matched
with the data rate at which data is communicated, the need
otherwise to select a highest power level corresponding to a
highest data rate, best to ensure successful communication of the
data, is obviated. By permitting operation at reduced power levels,
lessened amounts of power are consumed during communications, and
improved system performance and capacity are permitted.
BACKGROUND OF THE INVENTION
Communication systems are endemic in modern society. Communication
of data pursuant to many varied types of communication services is
regularly needed. A communication system is used by which to
effectuate the communication of the data. Due to advancements in
communication technologies, new types of communication systems are
being developed.
A communication system includes at least a first communication
station and a second communication station interconnected by way of
a communication channel. Data is communicated by the first
communication station, referred to as a sending station, to the
second communication station, referred to as a receiving station,
by way of the communication channel. Data that is to be
communicated by the sending station is converted, if needed, into a
form to permit the data to be communicated upon the communication
channel. And, the receiving station detects the data communicated
upon the communication channel and recovers the informational
content thereof.
A radio communication system is a type of communication system. In
a radio communication system, a radio channel, defined upon a radio
air interface, forms the communication channel interconnecting the
sending and receiving stations. Conventional wireline communication
systems, in contrast, require the use of fixed, wireline
connections extending between the communications stations upon
which to define the communication channel.
A radio communication system provides various advan-tages in
contrast to a wireline counterpart. Initial installation and
deployment costs associated with a radio communication system are
generally less than the costs required to install and deploy a
corresponding wireline communication system. And, a radio
communication system can be implemented as a mobile communication
system in which one or more of the communication stations operable
therein is permitted mobility.
A cellular communication system is an exemplary type of mobile
radio communication system. Cellular communication systems have
been installed throughout significant portion of the populated
areas of the world and have achieved wide levels of usage. A
cellular radio communication system is a multi-user communication
system in which radio communications are provided with a plurality
of mobile stations. Telephonic communication of voice and data is
effectuable by way of the mobile stations. Mobile stations are
sometimes of sizes to permit their convenient carriage by users of
the mobile stations.
A cellular radio communication system includes network
infrastructure, that is installed throughout the geographical area
that is encompassed by the communication system. Mobile stations
operable in the cellular communication system communicate, by way
of radio channels, with base stations that form parts of the
network infrastructure of the communication system.
Base stations are fixed-site radio transceiver that transceive data
with the mobile stations. The base stations are installed at
spaced-apart locations throughout the geographical area encompassed
by the communication system. Each of the base stations defines a
cell, formed of a portion of the geographical area. A cellular
communication system is so-called because of the cells that
together define the coverage area of the communication system.
When a mobile station is positioned within a cell defined by a base
station, communications are generally effectuable with the base
station that defines the cell. Due to the inherit mobility of a
mobile station, the mobile station might travel between cells
defined by different ones of the base stations. Continued
communications with the mobile station is provided through
communication hand off procedures between successive ones of the
base stations defining the successive ones of the cells through
which the mobile station passes. Through appropriate positioning of
the base stations, the mobile station, wherever positioned within
the area encompassed by the communication system, shall be within
communication proximity of at least one base station.
Only relatively low-powered signals need to be generated to
effectuate communications between a mobile station and a base
station when the base stations are suitably positioned at selected
spaced-apart locations. Hand-offs of communications between the
successive base stations permit continued communications without
necessitating increases in the power levels at which the
communication signals are transmitted. And, because the signals
that are generated are all generally of low powered levels, the
same radio channels are able to be reused at different locations of
the cellular communication system. The frequency spectrum allocated
to a cellular communication system is thereby efficiently
utilized.
A cellular communication system is constructed, generally, to be
operable pursuant to an operating specification of a particular
communication standard. Successive generations of communication
standards have been developed, and operating specifications
defining their operational parameters have been promulgated.
First-generation and second-generation cellular communication
systems have been deployed and have achieved significant levels of
usage. Third-generation and successor-generation systems are
undergoing development, standardization, and, at least with respect
to the third-generation systems, partial deployment.
An exemplary third-generation cellular communication system is a
system that operates pursuant to the operating protocol set forth
in a CDMA 2000 operating specification. A CDMA 2000 cellular
communication system, constructed in conformity with the CDMA 2000
operating specification, provides for packet-based data
communication services.
Various technology proposals by which to effectuate communication
of packet data at high data rates in a CDMA 2000 communication
system have been proposed. By transmitting data at high data rates,
increased amounts of data are able to be communicated in a given
time period.
The 1xEV-DV data communication service is one such proposal. And,
the 1xEV-DO data communication service is another such proposal.
These data communication services provide for the communication of
data at any of several selected data rates. And, systems providing
for such communication services are sometimes referred to as being
multi rate communication systems. Other communication systems that
permit data to be communicated at any of two or more different data
rates are also sometimes referred to as being multi rate, or
multiple, data rate systems.
In the CDMA 2000 system that provides for multiple data rate
communication services, data that is to be communicated is
communicated at selected data rates on reverse links. That is to
say, data that is communicated by a mobile station to a network
portion of the communication system is communicated, upon a reverse
link channel at a selected data rate. A Pilot signal is also
communicated by the mobile station to the network infrastructure
along with the communication of the data. The pilot signal is
communicated upon a reverse pilot channel, and the data is
communicated upon a data channel. The pilot signal is used at the
network infrastructure to assist in coherent demodulation of the
data communicated upon the data channel.
In conventional CDMA 2000 systems, i.e., CDMA communication systems
that do not provide for high data rate communications at multiple
data rates that are quickly changeable, the pilot signal is of a
constant, or slowly changing, signal-to-noise ratio (SNR) level
(e.g., received pilot signal to noise ratio). However, when
employed in a system that provides for multiple data rate
communications, such as 1xEV-DV communication services, fast
scheduling and rate control impact the power control operation of
the communication system. Conventionally, the SNR level of the
pilot signal must be set at a high SNR level to ensure successful
communication of the data at a highest data rate of the multiple
data rates. In the event that data is communicated at a data rate
that is lower than the highest data rate, the pilot signal is of a
SNR level that is greater than that which is needed. The pilot
signal, during such times, therefore, is of an excessive power
level. Communication performance in the communication system is
adversely affected. And, when the mobile station is powered by a
battery power supply, the battery power supply is depleted of
stored energy at a rate greater than that which is required.
If a better manner could be provided by which better to match the
power level of the pilot signal with the data rate at which the
data associated therewith is communicated, improved system
performance would be possible.
It is in light of this background information related to radio
communication systems capable of communicating data at multiple
data rates that the significant improvements of the present
invention have evolved.
SUMMARY OF THE INVENTION
The present invention, accordingly, advantageously provides
apparatus, and an associated method, by which to facilitate
communications in a radio communication system that provides for
data communications at multiple data rates.
Through operation of an embodiment of the present invention, a
pilot, or other control, signal is provided that is of levels
related to the data rates at which the data is communicated. When
the data rate at which data is communicated is changed, the levels
at which the pilot, or other control, signal is generated
correspondingly changes.
That is to say, through operation of an embodiment of the present
invention, the pilot, or other control, signal is of a level that
is matched with the data rate at which the data is communicated.
The need otherwise to select a highest power level corresponding to
a highest data rate to ensure successful communication of the data
is obviated. Operation is permitted, thereby, at reduced power
levels. And, lessened amounts of power are consumed during
communication operations, and improved system performance and
increased system capacity are permitted.
When implemented in a CDMA 2000, cellular communication system that
provides for multiple data rates of data communications, such as
the date rates available in an 1xEV-DV communication service, extra
pilot power on the reverse link is provided. The existing operating
specification defines, on the reverse link, extending from a mobile
station to the network infrastructure of the communication system,
both a reverse fundamental channel and a reverse supplemental
channel. The reverse supplemental channel is provided, in
significant part, for the communication of data pursuant to a
1xEV-DV communication service.
A reverse pilot channel is also defined. The pilot signal is sent
by the mobile station on the reverse pilot channel along with data
on the reverse fundamental channel.
Pursuant to operation of an embodiment of the present invention, a
reverse supplemental pilot channel is also defined. And, the mobile
station additionally, selectably, sends a supplemental pilot signal
thereon. The data communicated upon the reverse fundamental channel
is, for instance, of constant, or varying among a set of predefined
low, data rates. The pilot signal sent on the reverse pilot channel
is selected to be of a level, preferably the smallest possible
level, to permit coherent demodulation of the data communicated
upon the reverse fundamental channel. The pilot signal on the
reverse supplemental pilot channel is of a power level selected
responsive to the data rate at which the data is sent upon the
reverse supplemental channel. When the data rate of the data
communicated upon the reverse supplemental channel is high, the
power level of the supplemental pilot signal sent on the reverse
supplemental pilot channel is correspondingly high. And, when the
data rate of the data communicated upon the supplemental channel is
low, the power level at which the reverse supplemental pilot signal
is sent is correspondingly low. By reducing the power level of the
supplemental pilot signal when the data rate of the associated data
is low, the power levels of the pilot signals are matched with the
data rates of the data that is communicated. And, thereby,
transmission of the pilot signals at power levels exceeding those
that are needed coherently to demodulate the data communicated upon
the reverse fundamental and supplemental channels does not occur.
Battery power consumption at the mobile station is not
unnecessarily consumed, and signal energy on the radio air
interface extending between the mobile station and the network
infrastructure is not unnecessarily high.
In one implementation, the pilot power level of the pilot signal
sent on the reverse pilot channel is always of a level needed for
the operation of the reverse fundamental channel. That is to say,
the T/P ratio of the reverse fundamental channel is independent of
the rate in the reverse supplemental channel. That extra pilot
power needed for operation of the reverse supplemental channels is
provided by the supplemental pilot signal sent upon the reverse
supplemental pilot channel. Fast power control is performed at the
network infrastructure, responsive to either the pilot signal sent
upon the reverse pilot channel alone, or responsive to the pilot
signals communicated upon both of the reverse pilot channel and the
reverse supplemental pilot channel.
In another implementation, the mobile station always sets the power
level of the pilot signal sent upon the reverse pilot channel.
Thereby, the T/P ratio of the data sent upon the reverse
fundamental channel is set according to the reverse supplemental
channel data rate of a prior frame of data, i.e., data sent during
a preceding time period. As the network infrastructure is aware of
the data rate of the data communicated during a prior time period,
the network infrastructure is also aware of the current T/P ratio
upon the reverse fundamental channel. And, the network
infrastructure adjusts the outer loop power control set point
responsive thereto. If the reverse supplemental channel requires
additional pilot power, in addition to the pilot power provided
upon the reverse pilot channel, then the reverse supplemental pilot
signal sent upon the reverse supplemental channel is used to
provide, and obtain, the additional power that is needed.
Pursuant to an additional embodiment of the present invention, a
manner is provided by which to facilitate stabling power control in
the event of a data rate change of communication of data during
operation of the communication system. In one implementation, the
adjustment of the pilot reference level is delayed. In another
implementation, conservative power level setting during rate and
power control transition is provided. And, in another
implementation, fast rate indications are provided.
In these and other aspects, therefore, apparatus, and an associated
method, is provided for a radio communication system. The radio
communication system provides for the communication of data by a
first communication station on at least a first data channel, at
least at a first selected data rate. A first control signal is
communicated upon a first control channel in which the first
control signal is targeted at a first trigger level during at least
a first selected time period. Communication of the data on the at
least the first data channel is facilitated. A second control
signal generator selectably generates a second control signal for
communication upon a second control channel. The second control
signal is targeted at a second target level. The second target
level is selected responsive to the at least the first selected
data rate at which the data is communicated on the at least the
first data channel.
A more complete appreciation of the present invention and the scope
thereof can be obtained from the accompanying drawings, which are
briefly summarized below, the following detailed description of the
presently-preferred embodiments of the invention, and the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates a functional block diagram of a radio
communication system operable pursuant to an embodiment of the
present invention.
FIG. 2 illustrates a representation of the relationship between the
data rates of data communicated upon reverse fundamental and
supplemental channels and the power levels of pilot signals sent on
reverse pilot and reverse supplemental pilot channels during
operation of an embodiment of the present invention.
FIG. 3 illustrates a representation, similar to that shown in FIG.
2, also representative of the relationship between data rates at
which data is communicated on reverse link channels and power
levels of pilot signals generated on reverse pilot and supplemental
pilot channels, here pursuant to operation of another embodiment of
the present invention.
FIG. 4 illustrates a representation of an exemplary power control
subchannel structure of the reverse pilot and supplemental pilot
channels defined pursuant to an embodiment of the present
invention.
FIG. 5 illustrates a representation, similar to those shown in
FIGS. 2-3, here showing the relationship between the data rates at
which data is communicated upon the reverse supplemental channel
and the power level of a pilot signal generated upon a reverse
pilot channel pursuant to operation of an embodiment of the present
invention.
FIG. 6 illustrates a timing diagram representing the timing
relationship of rate request and grant scheduling pursuant to
operation of an embodiment of the present invention.
FIG. 7 illustrates a representation of the generation of rate
indications on a reverse pilot channel generated pursuant to
operation of an embodiment of the present invention.
DETAILED OF THE DESCRIPTION
Referring first to FIG. 1, a radio communication system, shown
generally at 10, provides for radio communications, in a multi-user
environment, with mobile stations, of which the mobile station 12
is representative. The communication system forms a multiple data
rate communication system in which data is communicated, selectably
at a selected data rate of a plurality of separate, allowable data
rates. In the exemplary implementation, the communication system
forms a CDMA 2000 cellular communication system that provides for
1xEV-DV communication services. That is to say, in the exemplary
implementation, the communication system is compliant, generally,
with the operating protocols set forth in the CDMA 2000/1xEV-DV
operating specification.
The teachings of the present invention, are, however, amenable for
use in other types of multi rate data communication systems. While
the following description of operation of various embodiments of
the present invention shall be described with respect to their
implementation in a CDMA 2000 cellular communication system that
provides for 1xEV-DV data communications, the teachings of the
present invention are analogously applicable to other types of
communication systems.
Two-way communication of data between a mobile station and a
network part of the communication system is provided. A radio air
interface is defined between the network part of the communication
system and mobile stations operable therein. Forward link channels
are defined upon forward links extending from the network part to
the mobile stations. And, reverse link channels are defined upon
reverse links extending from the mobile stations to the network
part of the communication system. Both control information and data
traffic is communicated between the network part and the mobile
stations upon the forward and reverse link channels.
The operating specification pursuant to which the communication
system is constructed to be in compliance defines various control
and data channels upon the forward and reverse links. Of
significance to an embodiment of the present invention, in the
exemplary implementation, a reverse fundamental channel (R-FCH) and
a reverse supplemental channel (R-SCH) are defined upon which to
communicate, from a mobile station to the network part, traffic
data, communicated pursuant to effectuation of a data communication
service. The arrow 14 represents the reverse fundamental channel
upon which data is communicated by the mobile station 12 to the
network part of the communication system, and the arrow 16 is
representative of a reverse supplemental channel upon which traffic
data is also communicated by the mobile station to the network
part. More particularly, the reverse supplemental channel is
generally utilized upon which to communicate 1xEV-DV data at any of
various selected data rates. The data rates at which the data is
communicated upon the reverse supplemental channel is susceptible
to abrupt changes.
Various control channels are also defined on the reverse link.
Included amongst the control channels is a reverse pilot channel
(R-PICH), represented by the arrow 22. Pursuant to an embodiment of
the present invention, an additional channel, a reverse
supplemental pilot channel (R-SPICH) is defined. The reverse
supplemental pilot channel is represented in the Figure by the
arrow 22. And, forward link channels, both traffic and control
channels, are represented in the Figure by the arrow 28.
The network infrastructure of the communication system is here
shown to include a base station 34. The base station includes
transceiver circuitry for transceiving data upon the forward and
reverse link channels defined upon the radio air interface
extending between the network part and the mobile stations of the
communication system. In the exemplary implementation, the base
station operates pursuant to a CDMA (code-division,
multiple-access) communication scheme. The base station further
includes circuitry and elements to perform various functions, such
as power control functions that power control of signals generated
during operation of the communication system.
The base station 34 forms a portion of a radio access network
portion of the network part of the communication system. The radio
access network also includes a base station controller (BSC) 36 to
which the base station 34 is coupled. The base station controller
operates, amongst other things, to control operation of the base
station 34, as well as other base stations to which the base
station controller is coupled. The radio access network is here
shown to be coupled to a packet data network (PDN) 38, here by way
of a gateway (GWY) 40. A correspondent node (CN) 42 is coupled to
the packet data network. The correspondent node is representative
of a communication node that forms an ultimate source, or ultimate
destination, of data communicated with the mobile station 12. A
computer station, a telephonic station, and a content server are
all exemplary of devices of which the correspondent node can be
comprised.
Various elements of the base station 34 are also represented in
FIG. 1. Here, the front end transmit and front end receive circuit
portions 48 and 52, respectively, are shown. The front end transmit
and receive portions perform functions such as up-conversion and
down-conversion, respectively, operations upon data that is
communicated upon the radio air interface. The front end receive
circuitry portion is coupled to a decoder and to a signal-to-noise
ratio (SNR) estimator 56. And, the decoder is coupled to a frame
error rate (FER) estimator 58. The estimators 56 and 58 operate
upon indications of data received by the front end receive
circuitry to generate estimates of signal to noise ratios and frame
error rates of the indications provided thereto. Values
representative of the estimate generated by the estimator 56 on the
line 62 are provided to a comparator 66. And, values representative
of the estimates generated by the estimator 58 on the line 67 are
provided to an outer loop power control element 74. The elements 66
and 74 form portions of the transmit chain of the base station. A
value of a target frame error rate (TG FER) 75 is also provided to
the outer loop power control element 74. The outer loop power
control element forms a value that is applied to the comparator 66,
and a comparator output is provided to the front transmit circuitry
48. Power control is effectuated through the communication of,
inter alia., power control commands that instruct the mobile
station as to at what power levels at which to communicate data on
the reverse data channel (R-FCH).
As mentioned previously, pilot signals are communicated by the
mobile station to facilitate coherent demodulation of the data
communicated upon the reverse data channels. The pilot signal is of
an adequate power level to permit the informational content of the
data communicated by the mobile station to the network
infrastructure adequately to be recovered. Because of the direct
relationship between the power level at which the pilot signal must
be sent and the data rate at which the traffic data is sent, and
its effect upon power control, conventionally the power level at
which the pilot signal is sent is set to be of a power level
corresponding to the power level required of the pilot signal
associated with data communicated at a highest possible data rate.
When data is communicated at a data rate less than the highest
possible data rate, the power level of the pilot signal is
unnecessary.
An embodiment of the present invention comprises apparatus, shown
generally at 82, embodied at mobile stations, such as the mobile
station 12. The apparatus includes a second pilot, or other
control, signal generator 84. The signal generator generates a
pilot signal of a power level responsive to the data rate at which
data is communicated by the mobile station upon the reverse
supplemental channel. In one implementation, the pilot signal is
unmodulated. In other implementations, the pilot signal is
modulated by a known sequence, by a pseudodeterminative sequence,
or by other values. The indication of the data rate at which the
data is communicated by the mobile station upon reverse
supplemental channel is provided to the second pilot signal
generator by way of the line 86. The indication is here represented
to be provided by a data source that forms part of the transmit
chain, together with the transmit circuitry of the mobile station.
And, the signal formed, or caused to be formed, by the second
control signal generator is communicated by the transmit circuitry
of the mobile station. As the data rate changes, the power level of
the additional pilot signal formed by the signal generator 84
correspondingly changes, thereby matching the power level of the
signal with the data rate of the traffic data that is
communicated.
FIG. 2 illustrates a representation of exemplary data rates of data
communicated upon the reverse fundamental channel 14 and the
reverse supplemental channel 16 during successive time frames or
other time periods. And, corresponding power levels at which pilot
signals are sent upon the reverse pilot channel 22 and reverse
supplemental pilot channel 24 pursuant to operation of an
embodiment of the present invention are also represented. In this
implementation, the power level of the pilot signal sent by the
mobile station upon the reverse pilot channel 24 is of a pilot
power level needed for operation of the reverse fundamental
channel. That is to say, the T/P ratio of the reverse fundamental
channel is independent of the rate of the reverse supplemental
channel. The additional pilot power that is needed for operation of
the reverse supplemental channel 16 is provided by the supplemental
pilot signal sent on the reverse supplemental pilot channel 24.
When detected at the base station, fast power control is performed
based upon pilot signals sent on the reverse pilot channel only, or
upon both the reverse pilot channel and the supplemental pilot
signal sent upon the reverse supplemental pilot channel.
In the even of variable rate operation, i.e., when the data rate at
which the data is communicated on the supplemental channel changes,
the pilot signal sent upon the reverse pilot channel is transmitted
at a lowest possible power level that can ensure the performance of
the communication of the data on the reverse fundamental channel.
The power level of the supplemental pilot signal sent upon the
reverse supplemental channel is set to be:
P=(10.sup.pilot.sup.--.sup.reference.sup.--.sup.level*0.125/10-1.0)*R-PIC-
H.
If the T/P ratio of the reverse supplemental channel is defined to
be the ratio of the power of the reverse supplemental channel to
the power of the combination of the reverse pilot channel and the
reverse supplemental pilot channel, then the T/P ratio of the
reverse supplemental channel is set to a value of a nominal
attribute gain of the rate that is currently used. Power is not
wasted. And, as the T/P ratio of the reverse fundamental channel is
independent of the rate of the reverse supplemental channel, the
power control loop is not disturbed by the data rate change in the
reverse supplemental channel.
FIG. 3 illustrates again the relationships between the data rates
of the data communicated upon the reverse fundamental and
supplemental channels 14 and 16 and the power levels of the pilot
signals upon reverse pilot channel and reverse supplemental pilot
channel 22 and 24 during successive time frames. In this
implementation, the power level of the pilot signal sent by the
mobile station sent on the reverse pilot channel is set by the
mobile station. And, hence, the T/P ratio of the reverse
fundamental channel, all according to the data rate of the data
communicated upon the reverse supplemental channel in a previous
frame. As the base station knows also the data rate of the data
communicated upon the reverse supplemental channel during the prior
time frame, the base station also knows of the current T/P ratio of
the data communicated upon the reverse fundamental channel and
adjusts the outer loop power control set point accordingly. If the
current reverse supplemental channel requires additional pilot
power than provided on the reverse pilot channel during the current
time frame, the reverse supplemental pilot channel is used to
communicate a supplemental pilot signal to provide the extra
power.
In this implementation, the power control loop is not independent
of the data rate change of the reverse supplemental channel. But,
the power control loop is relatively undisturbed by the rate change
in that the base station is aware of how to adjust the outer loop
power control set point at each frame boundary. In this scheme, an
improved SNR estimate is provided for use upon inner loop power
control as the pilot signal sent on the reverse pilot channel is
generally of a relatively high power. Hence, the power control made
possible in this implementation is fairly accurate.
FIG. 4 illustrates a representation, shown generally at 102, of
exemplary power control subchannel structures of the reverse pilot
channel 22 and the reverse supplemental pilot channel 24. As
illustrated, the reverse pilot channel is formed of a first portion
104 of a length of 1152 chips and a 384 chip -length reverse power
control subchannel 106. Similarly, the reverse supplemental pilot
channel 24 is also formatted to include a first portion 108 of a
1152 chip length and a 384 chip length portion 112 forming the
reverse pilot control subchannel values. A code, for example,
W.sub.32.sup.64 can be assigned to the reverse supplemental pilot
channel. Backward compatibility is preserved through use of this
type of structure.
FIG. 5 illustrates a representation of the relationship between the
data rates at which communication data is communicated upon the
reverse fundamental and supplemental channels 14 and 16 and the
power level of the pilot signal sent upon the reverse pilot
channel. In this implementation, the reference level of the pilot
signal is delayed following a data rate change of the communication
data, communicated upon the data channels. At time 106, the outer
loop power control set point is as indicated by the opposing
arrows. This is the power control set point prior to a rate change
of data communicated upon the reverse supplemental channel. At time
108, the data rate of the data communicated upon the reverse
supplemental channel increases. Time 110 defines the start of a
subsequent time frame. And, thereafter, during a subsequent time
frame, the pilot power and outer loop set point is adjusted. During
this subsequent time period, the quality of the reverse fundamental
channel and the reverse supplemental channel is maintained. At time
112, the data rate of the data communicated upon the reverse
supplemental channel again changes. And, subsequent to time 114,
the pilot power is again adjusted. And, as indicated at the time
116, the outer loop set point is again indicated by the opposing
arrows.
During the first frame following the data rate change at the time
108, a sequence of procedures is performed at the mobile station.
The T/P ratio of the reverse fundamental channel is maintained.
And, the T/P ratio of the reverse supplemental channel is adjusted
according to the nominal attribute gain of the new data rate plus
the difference between the pilot reference level and the new data
rate and the old data rate. During this frame, the power level of
the reverse supplemental channel is set according to the new rate,
but the target received SNR of the reverse pilot channel and
reverse fundamental channel are maintained at the same level as in
the prior frame. And, at the base station, as the base station is
unaware of the rate change of the data communicated upon the
reverse supplemental channel, the base station power control
actions continue as is no rate change has oceurred.
During the second time frames, commencing at the time 110,
following the data rate change, the mobile station adjusts the
power level of the pilot signal by the difference between the pilot
reference level of the new data rate and the old data rate.
Additionally, the T/P ratio of the reverse supplemental channel is
adjusted according to the nominal attribute gain of the new data
rate. And, the T/P ratio of the reverse fundamental channel is
adjusted according to the multiple channel gain of the new data
rate. At the base station, the rate indicator in the first frame
following the data rate change is received. The base station
thereby has knowledge of the new data rate. And, the base station
adjusts the outer loop power control threshold to the initial
target outer loop power control threshold of the new data rate.
FIG. 6 illustrates rate requests 118, rate grants 122, and reverse
supplemental channel values 124 during operation of an embodiment
of the present invention. In this implementation, data rate changes
and power level adjustments, and adjustments to the T/P ratios are
made according to the nominal attribute gain and multiple channel
adjustment gains, all as specified in the operating specification
of CDMA 2000. Without the knowledge of the current rate, the base
station assumes the mobile station to transmit at a highest rate
allowed by the previous rate grant. And, the outer loop power
control threshold is set accordingly.
In the exemplary operations set forth in FIG. 6, the rate of the
data communicated upon the reverse supplemental channel is always
equal to or less than, the data rate that is granted by the base
station. That is to say, Rate_I is less than or equal to
Rate_grant_I. Because the base station does not know the data rate
of the data communicated upon the reverse supplemental channel
until the rate indicator is received correctly, the base station
assumes the current rate, Rate_I equals the Rate_grant_i. And, the
outer loop power control threshold is set accordingly. Through this
operation, there is always enough power in the pilot signal sent on
the reverse pilot channel to guarantee the required frame error
rate on the reverse supplemental channel.
FIG. 7 illustrates an implementation in which a fast rate
indication is multiplexed into the reverse pilot channel, thereby
to provide the base station with an indication of the data rate
change at the earliest possible time. The first sequence 126,
illustrates the reverse pilot channel and the reverse power control
subchannel during successive time periods within a time frame, each
defining a power control group 128.
The second sequence illustrates the reverse pilot and reverse pilot
channel and reverse power control subchannel together with a
reverse fast rate indication subchannel (R-FRISCH) 132 defined
pursuant to an embodiment of the present invention. And, the third
sequence illustrates the reverse pilot channel, the reverse fast
rate indication subchannel and reverse power control subchannel
defined pursuant to operation of another embodiment of the present
invention.
As the Figure illustrates, selected power control bits, such as the
first one or two power control bits of the reverse link power
control subchannel are punctured with values that define the
reverse fast rate indication subchannel. In one implementation, a
pilot signal generator, such as the pilot signal generator 84 shown
in FIG. 1 also operates as a rate indication generator that
generates rate indications that indicate the data rate that is
inserted into the illustrated positions. In another implementation,
the values are inserted even earlier. Alternately, the mobile
station can also puncture a portion of the reverse pilot channel in
the first and second power control group. The rate indication bits
inserted into these positions form this subchannel, the R-FRISCH.
The mobile station changes data rates and adjusts the power levels
and T/P ratios according to the nominal attribute gain and multiple
channel adjustment gain, all as specified in the operating
specification of the CDMA 2000 system. The base station holds the
outer loop power control thresholds in the first one or two power
control groups of this frame, and adjusts the outer loop power
control threshold thereafter according to the rate change
information conveyed in the reverse fast rate indication
subchannel. Fast rate indication can alternately be realized in
other manners, such as by multiplexing the values together with the
reverse rate indicator channel (R-RICH). The definition and use of
the R-FRISCH permits a base station to adjust the outer loop power
control threshold quickly. The bits can also be used together with
the R-RICH to decode the detail rate indication information in a
finer resolution.
Through operation of any of these embodiments of the present
invention, fast stabling of the power control loop is provided with
minimal change to the existing operating specification.
The preferred descriptions are of preferred examples for
implementing the invention, and the scope of the invention should
not necessarily be limited by this description. The scope of the
present invention is defined by the following claims.
* * * * *