U.S. patent application number 13/895817 was filed with the patent office on 2013-09-26 for transport format combination selection in a wireless transmit/receive unit.
The applicant listed for this patent is Stephen G. Dick, Stephen E. Terry, Guodong Zhang. Invention is credited to Stephen G. Dick, Stephen E. Terry, Guodong Zhang.
Application Number | 20130250892 13/895817 |
Document ID | / |
Family ID | 34798009 |
Filed Date | 2013-09-26 |
United States Patent
Application |
20130250892 |
Kind Code |
A1 |
Zhang; Guodong ; et
al. |
September 26, 2013 |
TRANSPORT FORMAT COMBINATION SELECTION IN A WIRELESS
TRANSMIT/RECEIVE UNIT
Abstract
A method and apparatus for selecting a TFC in a wireless
transmit/receive unit (WTRU) is disclosed. The WTRU estimates a
transmit power for each of a plurality of available transport
format combinations (TFCs). A TFC is selected for an uplink
dedicated channel and a TFC is selected for an enhanced uplink (EU)
channel. The TFC for the dedicated channel is selected first and
independently of the TFC selection of the EU channel. The TFC for
the EU channel is selected within a remaining WTRU transmit power
after the TFC selection for the dedicated channel.
Inventors: |
Zhang; Guodong; (Syosset,
NY) ; Terry; Stephen E.; (Northport, NY) ;
Dick; Stephen G.; (Nesconset, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Zhang; Guodong
Terry; Stephen E.
Dick; Stephen G. |
Syosset
Northport
Nesconset |
NY
NY
NY |
US
US
US |
|
|
Family ID: |
34798009 |
Appl. No.: |
13/895817 |
Filed: |
May 16, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12422516 |
Apr 13, 2009 |
8483148 |
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13895817 |
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|
11705638 |
Feb 12, 2007 |
7522557 |
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12422516 |
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11019489 |
Dec 22, 2004 |
7215655 |
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11705638 |
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60535426 |
Jan 9, 2004 |
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Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04W 52/146 20130101;
H04W 52/286 20130101; H04W 52/346 20130101; H04W 52/226 20130101;
H04W 52/60 20130101; H04W 52/262 20130101; H04W 72/02 20130101;
H04W 52/267 20130101 |
Class at
Publication: |
370/329 |
International
Class: |
H04W 72/02 20060101
H04W072/02 |
Claims
1. A method implemented in a wireless transmit/receive unit (WTRU)
for selecting a transport format combination (TFC), the WTRU being
configured to process more than one channel for uplink
transmission, the method comprising: estimating a transmit power
for each of a plurality of available TFCs; and selecting a TFC for
an uplink dedicated channel and a TFC for an enhanced uplink (EU)
channel, wherein the TFC for the dedicated channel is selected
first and independently of the TFC selection of the EU channel, and
wherein the TFC for the EU channel is selected within a remaining
WTRU transmit power after the TFC selection for the dedicated
channel.
2. The method of claim 1 wherein one TFC is selected for each
transmit time interval (TTI) of the dedicated channel and one TFC
is selected for each TTI of the EU channel.
3. The method of claim 1 wherein the remaining WTRU transmit power
is estimated every transmit time interval of either the EU channel
or the dedicated channel.
4. The method of claim 1 wherein a minimum set of TFCs is reserved
for each uplink channel, whereby each uplink channel always has a
possibility to transmit the minimum set of TFCs even when the
minimum set of TFCs is in excess power.
5. The method of claim 4 further comprising scaling down physical
channels in each uplink channel in response to a transmit power of
at least one uplink channel being in excess power.
6. The method of claim 4 wherein the minimum set of reserved TFCs
is one or more protocol data units per medium access control
(MAC-d) flow or logical channel per transmit time interval.
7. The method of claim 1 wherein the selecting a TFC further
comprises selecting a TFC for each uplink channel within an
individual maximum allowed transmit power designated to each uplink
channel.
8. The method of claim 7 wherein the individual maximum allowed
transmit power is determined by at least one of a data rate,
quality of service and relative priority between uplink
channels.
9. The method of claim 7 wherein a minimum set of TFCs is reserved
for each uplink channel, whereby each uplink channel always has a
possibility to transmit the minimum set of TFCs even when the
minimum set of TFCs is in excess power.
10. The method of claim 9 further comprising scaling down physical
channels in each uplink channel in response to a transmit power of
at least one uplink channel being in excess power.
11. The method of claim 9 wherein the minimum set of reserved TFCs
is one or more protocol data units per medium access control
(MAC-d) flow or logical channel per transmit time interval.
12. The method of claim 1 wherein the transmit power for each of a
plurality of available TFCs is estimated in each transmit time
interval.
13. A wireless transmit/receive unit (WTRU) for selecting transport
format combinations (TFCs) for a plurality of uplink channels, the
WTRU comprising: a transmit power estimation unit configured to
estimate a transmit power for each of a plurality of available
TFCs; and a TFC selection unit configured to select a TFC for an
uplink dedicated channel and a TFC for an enhanced uplink (EU)
channel, wherein the TFC for the dedicated channel is selected
first and independently of the TFC selection of the EU channel, and
wherein the TFC for the EU channel is selected within a remaining
WTRU transmit power after the TFC selection for the dedicated
channel.
14. The WTRU of claim 13 wherein one TFC is selected for each
transmit time interval (TTI) of the dedicated channel and one TFC
is selected for each TTI of the EU channel.
15. The WTRU of claim 13 wherein the remaining WTRU transmit power
is estimated every transmit time interval of either the EU channel
or the dedicated channel.
16. The WTRU of claim 13 wherein a minimum set of TFCs is reserved
for each uplink channel, whereby each uplink channel always has a
possibility to transmit the minimum set of TFCs even when the
minimum set of TFCs is in excess power.
17. The WTRU of claim 16 wherein the WTRU is configured to scale
down physical channels in each uplink channel in response to a
transmit power of at least one uplink channel being in excess
power.
18. The WTRU of claim 16 wherein the minimum set of reserved TFCs
is one or more protocol data units per medium access control
(MAC-d) flow or logical
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/705,638 filed Feb. 12, 2007, which is a
continuation of U.S. patent application Ser. No. 11/019,489 filed
Dec. 22, 2004, which issued on May 8, 2007 as U.S. Pat. No.
7,215,655, which claims priority from U.S. Provisional Application
No. 60/535,426 filed Jan. 9, 2004 which are incorporated by
reference as if fully set forth.
FIELD OF INVENTION
[0002] The present invention is related to a wireless communication
system.
BACKGROUND
[0003] Under the current Third Generation Partnership Project
(3GPP) standards, a WTRU is required to estimate a transmission
power for each TFC. In the case that a certain TFC would require
more transmission power than the maximum allowed WTRU transmission
power, the WTRU should limit the usage of that TFC.
[0004] The WTRU continuously evaluates which TFCs can be used for
transmission. The evaluation is performed using the estimated WTRU
transmit power of a given TFC. When any TFC is restricted for
exceeding a transmit power limit, the medium access control (MAC)
entity in the WTRU notifies an upper layer to reduce the data rate,
if applicable.
[0005] Under the current 3GPP standards, a WTRU has only one coded
composite transport channel (CCTrCH) in uplink transmission.
Therefore, the WTRU transmit power is the transmit power of the
CCTrCH, which is determined by the TFC used for the CCTrCH.
[0006] In order to improve uplink coverage, throughput and
transmission latency for uplink transmissions, enhanced uplink (EU)
is currently being investigated in 3GPP. With EU implementation, a
WTRU may have more than one CCTrCH in uplink transmissions; one for
the regular dedicated channel (DCH) and the other for EU enhanced
dedicated channel (E-DCH). In this case, the WTRU transmit power
will be the sum of the transmit power of two CCTrCHs.
[0007] The WTRU transmit power is determined jointly by the TFCs of
the two CCTrCHs. The combination of the TFC used by the dedicated
CCTrCH and the TFC used by the EU CCTrCH is defined as the TFC pair
of the WTRU whose transmit power is determined jointly by the TFCs
of the two CCTrCHs. This is not an optimal method of determining
the TFCs for more than one CCTrCH.
[0008] There is a need for an efficient method for selecting a
combination of TFCs for more than one CCTrCHs in uplink
transmission.
SUMMARY
[0009] A method and apparatus for selecting a TFC in a wireless
transmit/receive unit (WTRU) is disclosed. The WTRU estimates a
transmit power for each of a plurality of available transport
format combinations (TFCs). A TFC is selected for an uplink
dedicated channel and a TFC is selected for an enhanced uplink (EU)
channel. The TFC for the dedicated channel is selected first and
independently of the TFC selection of the EU channel. The TFC for
the EU channel is selected within a remaining WTRU transmit power
after the TFC selection for the dedicated channel.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a flow diagram of a general process for selecting
TFCs in accordance with a first embodiment of the present
invention.
[0011] FIG. 2 is a flow diagram of a process for selecting TFCs in
accordance with a second embodiment of the present invention.
[0012] FIG. 3 is a flow diagram of a process for selecting TFCs in
accordance with a third embodiment of the present invention.
[0013] FIG. 4 is a flow diagram of a process for selecting TFCs in
accordance with a fourth embodiment of the present invention.
[0014] FIG. 5 is a block diagram of an apparatus for selecting TFCs
in accordance with the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] Hereafter, the terminology "WTRU" includes but is not
limited to a user equipment, a mobile station, a fixed or mobile
subscriber unit, a pager, or any other type of device capable of
operating in a wireless environment.
[0016] The features of the present invention may be incorporated
into an integrated circuit (IC) or be configured in a circuit
comprising a multitude of interconnecting components.
[0017] Hereinafter, the present invention will be described with
reference to a system supporting two CCTrCHs, (i.e., a dedicated
CCTrCH and an EU CCTrCH). However, it should be noted that the
present invention is applicable to a system supporting more than
two CCTrCHs.
[0018] FIG. 1 is a flow diagram of a process 100 for selecting TFCs
in accordance with a first embodiment of the present invention. The
WTRU is configured to process a dedicated CCTrCH and an EU CCTrCH
simultaneously in uplink transmission. The transmit power of the
WTRU is limited to a maximum allowed WTRU transmit power, which is
set by the wireless communication system. In each transmit time
interval (TTI), the WTRU estimates the transmit power for each of a
plurality of available TFCs (step 102) for each CCTrCH. The WTRU
estimates the transmit power of each TFC over a predetermined
period taking into account the gain factor of each corresponding
TFC. The WTRU then selects TFCs for transmission on each CCTrCH
among a plurality of available TFCs, such that the sum of the
estimated transmit power of the selected TFCs for the dedicated
CCTrCH and the EU CCTrCH does not exceed the maximum allowed WTRU
transmit power (step 104).
[0019] Additionally, the dedicated CCTrCH, the EU CCTrCH, or both
may be provided with a capability of transmitting a reserved
minimum set of TFCs even when the power required for transmission
of these TFCs exceeds the maximum allowed WTRU transmit power. TFCs
that require power greater then the maximum allowed transmit power
are defined to be in an excess power state. The minimum set is for
reserving a lowest rate in a CCTrCH, thereby maintaining the basic
services for the channel. Since in the EU CCTrCH there is only one
TrCH, the minimum set corresponds to a lowest rate per logical
channel or MAC-d flow mapped to the EU TrCH. The minimum set of
TFCs may be one transport block per TTI for each channel mapped to
the CCTrCH or a number of transport blocks per TTI corresponding to
a guaranteed bit rate (GBR).
[0020] The reserved minimum set of TFCs may be transmitted in an
excess power state. In order to maintain the transmit power within
the allowed maximum level, a WTRU scales down power on physical
channels mapped to the dedicated CCTrCH, the EU CCTrCH, or all
physical channels present.
[0021] Regardless of the TFC selection, the EU CCTrCH may be
provided with a minimum reserved set of TFCs that is one or more
transport blocks per logical channel or MAC-d flow mapped to the EU
CCTrCH. A transport block is one or more radio link control (RLC)
protocol data units (PDUs). One or more transport blocks is
equivalent to a data rate. The reserved set of TFCs can be
transmitted in an excess power state by scaling down power on
either the physical channels mapped to the EU CCTrCH, the dedicated
CCTrCH or all present UL channels.
[0022] FIG. 2 is a flow diagram of a process 200 for selecting TFCs
in accordance with a second embodiment of the present invention.
TFC selection of the dedicated CCTrCH is prioritized over TFC
selection of the EU CCTrCH. In each TTI of the dedicated CCTrCH,
the WTRU estimates the transmit power requirement for each of a
plurality of available TFCs configured for the dedicated CCTrCH
(step 202). The WTRU selects a TFC for the dedicated CCTrCH first,
without considering the power requirement of the EU CCTrCH (step
204). After the TFC for the dedicated CCTrCH is selected, at each
TTI of the EU CCTrCH the WTRU selects a TFC for the EU CCTrCH
within the remaining WTRU transmit power after the power required
for the selected TFC for the dedicated CCTrCH is deducted from the
maximum allowed WTRU transmit power (step 206). The TFC selection
of the dedicated CCTrCH is not affected by the operation of EU
CCTrCH, while the TFC selection of the EU CCTrCH is affected and
limited by the operation of the dedicated CCTrCH.
[0023] The remaining power for the EU CCTrCH is estimated either
each dedicated CCTrCH TTI or each EU CCTrCH TTI. At each TTI of the
EU CCTrCH, the remaining power available for the EU CCTrCH is
estimated as the maximum allowed WTRU transmit power minus the
power required by transmission of the selected dedicated CCTrCH
TFC. Alternatively, at each TTI of the dedicated CCTrCH, the
remaining power available for the EU CCTrCH is estimated as the
maximum allowed WTRU transmit power minus the power required to
support transmission of the selected dedicated CCTrCH TFC.
[0024] In process 200, the EU CCTrCH may allow transmission of a
minimum set of TFCs even when these TFCs are in excess power state.
An EU TFC is in excess power state when the estimated remaining
power is less then the calculated transmission power requirement
for the EU CCTrCH TFC. The EU minimum set reserves a lowest or
guaranteed rate on channels mapped to the EU CCTrCH, and thereby
maintains the basic services for EU channels. Since in the EU
CCTrCH there is only one TrCH, the minimum set corresponds to a
lowest rate per logical channel or MAC-d flow mapped to the EU
TrCH. The minimum set of TFCs may be one transport block per TTI
for each channel mapped to the CCTrCH or a number of transport
blocks per TTI corresponding to a guaranteed bit rate (GBR). When
transmitting a TFC in excess power state, in order to maintain the
transmit power within the allowed maximum level, the WTRU scales
down power on physical channels mapped to the EU CCTrCH, the
dedicated CCTrCH, or all physical channels present.
[0025] FIG. 3 is a flow diagram of a process 300 for selecting TFCs
in accordance with a fourth embodiment of the present invention.
The WTRU gives priority to dedicated CCTrCH TFC selection while
reserving transmit power for a minimum set of EU CCTrCH TFCs (step
302). A minimum set of TFCs for an EU CCTrCH is defined to reserve
a lowest or guaranteed rate for channels mapped to the EU CCTrCH.
Since in the EU CCTrCH there is only one TrCH, the minimum set
corresponds to a lowest rate per logical channel or MAC-d flow
mapped to the EU TrCH. The minimum set of TFCs may be one transport
block per TTI for each channel mapped to the CCTrCH, or a number of
transport blocks per TTI corresponding to a GBR.
[0026] The EU CCTrCH may allow transmission of a minimum set of
TFCs even when these TFCs are in excess power state. An EU TFC is
in excess power state when the estimated remaining power is less
then the calculated transmission power requirement for the EU TFC.
When transmitting a TFC in excess power state, in order to maintain
the transmit power within the allowed maximum level, the WTRU
scales down power on physical channels mapped to the EU CCTrCH, the
dedicated CCTrCH, or all physical channels present.
[0027] When a TFC is in an excess power state (with reduced power),
the quality of the transmission is reduced, (i.e., lower SIR,
higher BLER, etc). This may defeat the purpose of maintaining the
minimum set. Therefore, in order to minimize the possibility that
the EU CCTrCH TFC has to be transmitted in an excess power state,
and to further insure the minimum set is really supported, in
process 300 transmit power is reserved for the EU minimum set when
TFC selection is performed on the prioritized dedicated CCTrCH.
[0028] TFC selection of the dedicated CCTrCH is prioritized over
TFC selection of the EU CCTrCH. In each TTI of the dedicated
CCTrCH, the WTRU estimates the transmit power for each of a
plurality of available TFCs configured for the dedicated CCTrCH and
TFCs associated with the EU CCTrCH minimum set (step 304). The WTRU
selects a TFC for the dedicated CCTrCH that has a power requirement
that does not exceed the maximum allowed transmit power minus the
power required to support the minimum set of TFCs on the EU CCTrCH
(step 306). After the TFC for the dedicated CCTrCH is selected, at
each TTI of the EU CCTrCH the WTRU selects a TFC for the EU CCTrCH
with the remaining transmit power after power required for the
selected the TFC for the dedicated CCTrCH is deducted from the
maximum allowed transmit power (step 308).
[0029] The remaining power for the EU CCTrCH is estimated either
each dedicated CCTrCH TTI or each EU CCTrCH TTI. At each TTI of the
EU CCTrCH, the remaining power available for the EU CCTrCH is
estimated as the maximum allowed WTRU transmit power minus the
power required by transmission of the selected dedicated CCTrCH
TFC. Alternatively, at each TTI of the dedicated CCTrCH, the
remaining power available for the EU CCTrCH is estimated as the
maximum allowed WTRU transmit power minus the power required to
support transmission of the selected dedicated CCTrCH TFC.
[0030] Since the dedicated CCTrCH TFC selection takes precedence
over the EU CCTrCH, and the power requirement may change during the
dedicated TTI, the minimum set of TFCs of the EU CCTrCH may still
be transmitted in an excess power state even though power was
reserved when the dedicated TFC was selected. In this situation, in
order to maintain the transmit power within the allowed maximum
level, the WTRU scales down all physical channels mapped to the EU
CCTrCH, the dedicated CCTrCH, or all physical channels present.
[0031] FIG. 4 is a flow diagram of a process 400 for selecting TFCs
in accordance with a third embodiment of the present invention. The
WTRU sets an individual maximum transmit power, or a ratio relative
to the maximum allowed WTRU transmit power, for a dedicated CCTrCH
and an EU CCTrCH (step 402). The maximum power level (or the ratio)
for each CCTrCH is a configurable parameter. The factors for
determining the maximum power level (or the ratio) for each CCTrCH
may include, but are not limited to, a data rate of each CCTrCH,
quality-of-service (QoS) of each CCTrCH and a relative priority
between the CCTrCHs.
[0032] In each TTI of the dedicated CCTrCH and in each TTI of the
EU CCTrCH, the WTRU estimates the transmit power for each of a
plurality of available TFCs (step 404). The WTRU then selects a TFC
for each CCTrCH within the individual maximum transmit power of
each CCTrCH (step 406). The TFC selection process for each CCTrCH
operates independently. The TFC of each CCTrCH is selected from
only those TFCs that can be supported by the individual maximum
power level determined for a particular CCTrCH.
[0033] The dedicated CCTrCH, the EU CCTrCH, or both may be provided
with a capability of transmitting a minimum set of TFCs. The
minimum set is for reserving a lowest rate for each channel mapped
to the CCTrCH, thereby maintaining the basic services for each
channel. Since in the EU CCTrCH there is only one TrCH, the minimum
set corresponds to a lowest rate per logical channel or MAC-d flow
mapped to the EU TrCH. The minimum set of TFCs may be one transport
block per TTI for each channel mapped to the CCTrCH or a number of
transport blocks per TTI corresponding to a GBR.
[0034] The minimum set of TFCs may be transmitted in an excess
power state. In this situation, in order to maintain the transmit
power within the allowed maximum level, the WTRU scales down all
physical channels mapped to the EU CCTrCH, the dedicated CCTrCH, or
all physical channels present.
[0035] FIG. 5 is a block diagram of an apparatus 500 for selecting
TFCs in accordance with the present invention. The apparatus 500
comprises a transmit power estimation unit 502, a TFC selection
unit 504, and a measurement unit 506. The transmit power estimation
unit 502 calculates an estimate of a transmit power for each of a
plurality of available TFCs. The TFC selection unit 504 selects a
TFC for each CCTrCH such that the sum of the estimated WTRU
transmit power for the selected TFCs is within a maximum WTRU
transmit power. The measurement unit 506 performs physical
measurements of the WTRU transmit power over a predetermined
period, and the transmit power estimation unit 502 calculates the
estimate of a transmit power of each TFC using the measurement
results and a gain factor of the corresponding TFC.
[0036] Although the features and elements of the present invention
are described in the preferred embodiments in particular
combinations, each feature or element can be used alone without the
other features and elements of the preferred embodiments or in
various combinations with or without other features and elements of
the present invention.
* * * * *