U.S. patent application number 15/432118 was filed with the patent office on 2017-06-01 for method and apparatus for selecting a radio link control protocol data unit size.
This patent application is currently assigned to InterDigital Patent Holdings, Inc.. The applicant listed for this patent is InterDigital Patent Holdings, Inc.. Invention is credited to Paul Marinier, Diana Pani, Vincent Roy, Stephen E. Terry.
Application Number | 20170156145 15/432118 |
Document ID | / |
Family ID | 40512424 |
Filed Date | 2017-06-01 |
United States Patent
Application |
20170156145 |
Kind Code |
A1 |
Marinier; Paul ; et
al. |
June 1, 2017 |
METHOD AND APPARATUS FOR SELECTING A RADIO LINK CONTROL PROTOCOL
DATA UNIT SIZE
Abstract
A method and apparatus are used to create RLC PDUs in advance of
the E-TFC selection for the MAC PDU that will include this or these
RLC PDU(s). The apparatus may be configured to pre-generate RLC
PDUs for transmission in a later TTI. This approach avoids large
peak processing requirement due to the tight delay constraint if
any RLC PDU to be included into a MAC PDU had to be created after
the determination of the size of this MAC PDU, i.e. after E-TFC
selection. The method and apparatus maintain an approximate match
between the size of an RLC PDU and the size of the MAC PDU it is
included into. Maintaining this approximate match ensures that the
RLC PDU error rate due to HARQ residual errors remains low. This
approach may be designed as "semi-radio aware" or "radio-aware with
delay".
Inventors: |
Marinier; Paul; (Brossard,
CA) ; Pani; Diana; (Montreal, CA) ; Terry;
Stephen E.; (Northport, NY) ; Roy; Vincent;
(Longueuil, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InterDigital Patent Holdings, Inc. |
Wilmington |
DE |
US |
|
|
Assignee: |
InterDigital Patent Holdings,
Inc.
Wilmington
DE
|
Family ID: |
40512424 |
Appl. No.: |
15/432118 |
Filed: |
February 14, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14490741 |
Sep 19, 2014 |
9609548 |
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15432118 |
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12239023 |
Sep 26, 2008 |
8879534 |
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14490741 |
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60975955 |
Sep 28, 2007 |
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60976319 |
Sep 28, 2007 |
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60982596 |
Oct 25, 2007 |
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61013173 |
Dec 12, 2007 |
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61026912 |
Feb 7, 2008 |
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61038682 |
Mar 21, 2008 |
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61038515 |
Mar 21, 2008 |
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61044765 |
Apr 14, 2008 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 72/044 20130101;
H04W 72/0446 20130101; H04L 1/1812 20130101; H04W 28/065 20130101;
H04L 47/36 20130101; H04W 28/06 20130101; H04W 80/02 20130101 |
International
Class: |
H04W 72/04 20060101
H04W072/04; H04L 12/805 20060101 H04L012/805; H04W 28/06 20060101
H04W028/06 |
Claims
1-55. (canceled)
56. A method for use in a wireless transmit/receive unit (WTRU),
the method comprising: choosing a size of a data field of an RLC
PDU to be multiplexed into a MAC-i PDU or a MAC-is PDU to match a
maximum amount of data allowed to be transmitted by a current grant
for a current transmission time interval (TTI); and pre-generating
the RLC PDU for transmission in a later TTI.
57. The method of claim 56, comprising determining that there is a
sufficient amount of data available for transmission.
58. The method of claim 56, wherein the RLC PDU is pre-generated
based on a condition that an amount of data in one or more
outstanding pre-generated RLC PDUs for a logic channel is less than
a predetermined limit for the current grant.
59. The method of claim 58, wherein the predetermined limit
corresponds to a factor multiplied by the maximum amount of data
allowed to be transmitted by the current grant for the current
TTI.
60. The method of claim 56, wherein the amount of data allowed to
be transmitted is based on a number of bits of a currently selected
enhanced dedicated channel (E-DCH) transport format combination
(E-TFC).
61. The method of claim 56, wherein the current grant is a
scheduled grant or a non-scheduled grant on a condition that the
data belongs to a logical channel mapped to a scheduled MAC-d flow
or a non-scheduled MAC-d flow.
62. A wireless transmit/receive unit (WTRU) comprising: a processor
configured to at least: choose a size of a data field of an RLC PDU
to be multiplexed into a MAC-i PDU or a MAC-is PDU to match a
maximum amount of data allowed to be transmitted by a current grant
for a current transmission time interval (TTI); and pre-generate
the RLC PDU for transmission in a later TTI.
63. The WTRU of claim 62, wherein the processor is configured to
determine that there is a sufficient amount of data available for
transmission.
64. The WTRU of claim 62, wherein the RLC PDU is pre-generated
based on a condition that an amount of data in one or more
outstanding pre-generated RLC PDUs for a logic channel is less than
a predetermined limit for the current grant.
65. The WTRU of claim 64, wherein the predetermined limit
corresponds to a factor multiplied by the maximum amount of data
allowed to be transmitted by the current grant for the current
TTI.
66. The WTRU of claim 62, wherein the amount of data allowed to be
transmitted is based on a number of bits of a currently selected
enhanced dedicated channel (E-DCH) transport format combination
(E-TFC).
67. The WTRU of claim 62, wherein the current grant is a scheduled
grant or a non-scheduled grant on a condition that the data belongs
to a logical channel mapped to a scheduled MAC-d flow or a
non-scheduled MAC-d flow.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
applications 60/982,596 filed on Oct. 25, 2007; 61/038,515 filed on
Mar. 21, 2008; 61/013,173 filed on Dec. 12, 2007; 61/026,912 filed
on Feb. 7, 2008; 61/038,682 filed on Mar. 21, 2008; 61/044,765
filed on Apr. 14, 2008; 60/975,955 filed on Sep. 28, 2007; and
60/976,319 filed on Sep. 28, 2007, which are incorporated by
reference as if fully set forth.
TECHNOLOGY FIELD
[0002] This application is related to wireless communications.
BACKGROUND
[0003] The Third Generation Partnership Project (3GPP) is a
collaboration between groups of telecommunications associations to
make a globally applicable third generation (3G) wireless
communications system.
[0004] The UMTS network architecture includes a Core Network (CN),
a UMTS Terrestrial Radio Access Network (UTRAN), and at least one
user equipment (UE). The CN is interconnected with the UTRAN via an
Iu interface.
[0005] The UTRAN is configured to provide wire less
telecommunication services to UEs, referred to as wireless
transmit/receive units (WTRUs) in this application, via a Uu radio
interface. A commonly employed air interface defined in the UMTS
standard is wideband code division multiple access (W-CDMA). The
UTRAN comprises one or more radio network controllers (RNCs) and
base stations, referred to as Node Bs by 3GPP, which collectively
provide for the geographic coverage for wireless communications
with the at least one UE. One or more Node Bs is connected to each
RNC via an Iub interface. The RNCs within the UTRAN communicate via
an Iur interface.
[0006] FIG. 1 is an exemplary block diagram of the UE 200. The UE
200 may include a radio resource control (RRC) entity 205, a radio
link control (RLC) entity 210, a medium access control (MAC) entity
215 and a physical (PHY) layer 1 (L1) entity 220. The RLC entity
210 includes a transmitting side subassembly 225 and a receiving
side subassembly 230. The transmitting side subassembly 225
includes a transmission buffer 235.
[0007] FIG. 2 is an exemplary block diagram of the UTRAN 300. The
UTRAN 300 may include an RRC entity 305, an RLC utility 310, a MAC
entity 315 and PHY L1 entity 320. The RLC entity 310 includes a
transmitting side subassembly 325 and a receiving side subassembly
330. The transmitting side subassembly 325 includes a transmission
buffer 335.
[0008] The 3GPP Release 6, introduced high-speed uplink packet
access (HSUPA) to provide higher data rates for uplink
transmissions. As part of HSUPA, a new transport channel, the
enhanced dedicated channel (E-DCH), was introduced to carry uplink
(UL) data at higher rates.
[0009] The MAC sublayer is configured to determine the number of
bits to be transmitted in a transmission time interval (TTI) for
the E-DCH transport channel. The MAC sublayer may be configured to
perform an E-DCH transport format combination (E-TFC) selection
process. The relative grant and absolute grants received on the
E-RGCH and E-AGCH adjust the maximum allowable E-DPDCH to DPCCH
power ration at which a WTRU may transmit.
[0010] FIG. 3 shows an overview of the RLC sub-layers. The RLC
sub-layer consists of RLC entities, of which there are three types:
Transparent Mode (TM), Unacknowledged Mode (UM), and Acknowledged
Mode (AM) RLC entities. An UM and a TM RLC entity may be configured
to be a transmitting RLC entity or a receiving RLC entity. The
transmitting RLC entity transmits RLC PDUs and the receiving RLC
entity receives RLC PDUs. An AM RLC entity consists of a
transmitting side for transmitting RLC PDUs and a receiving side
for receiving RLC PDUs.
[0011] Each RLC entity is defined as a sender or as a receiver
depending on elementary procedures. In UM and TM, the transmitting
RLC entity is a sender and a peer RLC entity is a receiver. An AM
RLC entity may be either a sender or a receiver depending on the
elementary procedure. The sender is the transmitter of acknowledged
mode data (AMD) PDUs and the receiver is the receiver of AMD PDUs.
A sender or receiver may be at either the UE or the UTRAN.
[0012] There is one transmitting RLC entity and one receiving RLC
entity for each TM and UM service. However, there is one combined
transmitting and receiving RLC entity for the AM service.
[0013] Both an UM RLC entity and a TM RLC entity use one logical
channel to send or receive data PDUs. An AM RLC entity may be
configured to use one or two logical channels to send or receive
both data PDUs and control PDUs. If only one logical channel is
configured, then the transmitting AM RLC entity transmits both data
PDUs and control PDUs on the same logical channel.
[0014] The AM RLC entity may be configured to create PDUs, wherein,
the RLC PDU size is the same for both data PDUs and control
PDUs.
[0015] Currently, an RLC entity is "radio unaware" or not aware of
current radio conditions. However, in the UL direction, an RLC
entity may be "radio aware" or aware of current radio conditions,
because both RLC and MAC protocols are located in the same node. As
a result, an RLC PDU size may be determined based on an
instantaneous available data rate.
[0016] However, when the RLC entity is designed to be "radio
unaware," the RLC entity generates RLC PDUs of a maximum size.
Depending on current radio conditions and a given grant, this may
result in the generation of more than one PDU per TTI.
Unfortunately, if the generated RLC PDU is larger than a selected
E-DCH transport format combination (E-TFC) size, then the generated
RLC PDU may be segmented.
[0017] Both "radio aware" and "radio unaware" RLCs have advantages
and disadvantages. The main disadvantages of radio unaware" are (a)
large overhead in case a small fixed RLC PDU size is used and (b)
large error rates due to residual hybrid automatic repeat request
(HARQ) errors in case MAC segmentation is used with a large fixed
RLC PDU size. (Note: residual HARQ error=the transmission of the
improved MAC (MAC-i/is) PDU has failed. If there is a large number
of segments, the chance that any of the MAC-i/is PDUs carrying a
segment fails is larger, thus the RLC PDU error rate
increases.)
[0018] As stated above, a "radio aware" RLC entity generates RLC
PDUs as a function of the E-TFC size of a MAC PDU (transport block
size). As a result, there is minimal overhead and low RLC PDU error
rate due to residual HARQ errors since the RLC PDUs do not need to
be segmented at the MAC. However, a "radio aware" RLC entity may
not be able to generate an RLC PDU at a given TTI because the
generation of the RLC PDU within a short amount of time may require
too much processing power.
[0019] A "Radio aware" RLC entity, will generate RLC PDUs that
match the transport block size which is optimal for minimizing the
RLC PDU error rate due to residual HARQ errors, however the "radio
aware" RLC entity will have a much higher overhead for very small
E-TFC sizes and a lower overhead for large transport block sizes.
Because a "radio aware" RLC generates a large RLC PDU when there is
a large E-TFC selection, there are problems when the large RLC PDU
needs to be retransmitted and the E-TFC selection decreases in
size. Further, the retransmission of the large RLC PDU requires the
generation of a large number of MAC segments. As a result, there
may be an increase of RLC PDU error rate due to HARQ residual
errors.
[0020] Accordingly, there exists a need for a method for use in an
RLC entity that generates RLC PDUs such that RLC overhead and RLC
PDU error rates due to HARQ residual errors are both reduced.
[0021] Therefore, methods of selecting the proper RLC PDU size
within the specified bounds would be desirable. More specifically,
methods to determine when the RLC PDU size should be calculated and
which value the RLC PDU size should be set to would be
desirable.
SUMMARY
[0022] A method and apparatus are used to create RLC PDUs in
advance of the E-TFC selection for the MAC PDU that will include
this or these RLC PDU(s). The WTRU may be configured to
pre-generate RLC PDUs for transmission in a later TTI. This
approach has the benefit of avoiding the large peak processing
requirement that would exist due to tight delay constraint if any
RLC PDU to be included into a MAC PDU had to be created after the
determination of the size of this MAC PDU, i.e. after E-TFC
selection. The method and apparatus described hereafter allow this
benefit while at the same time maintainign most of the time an
approximate match between the size of an RLC PDU and the size of
the MAC PDU it is included into. Maintaining this approximate match
ensures that the RLC PDU error rate due to HARQ residual errors
remains low. This approach may be designed as "semi-radio aware" of
"radio-aware with delay".
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] A more detailed understanding may be had from the following
description, given by way of example in conjunction with the
accompanying drawing wherein:
[0024] FIG. 1 is an exemplary block diagram of the UE;
[0025] FIG. 2 is an exemplary block diagram of the UTRAN;
[0026] FIG. 3 shows an overview of the RLC sub-layers;
[0027] FIG. 4 shows a wireless communication system including a
plurality of WTRUs, a Node-B, a CRNC, an SRNC, and a core
network;
[0028] FIG. 5 is a functional block diagram of a WTRU and the
Node-B of the wireless communication system of FIG. 4;
[0029] FIG. 6 is a block diagram of a method for use in a wireless
transmit/receive unit (WTRU) for pre-generating a radio link
control (RLC) protocol data units (PDUs) tor transmission in a
later TTI; and
[0030] FIG. 7 shows an example of a combination of embodiments for
the various steps described in FIG. 6.
DETAILED DESCRIPTION
[0031] When referred to hereafter, the terminology "wireless
transmit/receive unit (WTRU)" includes but is not limited to a
WTRU, a user equipment (UE), a mobile station, a fixed or mobile
subscriber unit, a pager, a cellular telephone, a personal digital
assistant (PDA), a computer, or any other type of user device
capable of operating in a wireless environment. When referred to
hereafter, the terminology "base station" includes but is not
limited to a Node-B, a site controller, an access point (AP), or
any other type of interfacing device capable of operating in a
wireless environment.
[0032] FIG. 4 shows a wireless communication system 400 including a
plurality of WTRUs 410, a Node-B 420, a CRNC 430, an SRNC 440 and a
core network 450. As shown in FIG. 4, the WTRUs 410 are in
communication with the Node-B 420, which is in communication with
the CRNC 430 and the SRNC 440. Although three WTRUs 410, one Node-B
420, one CRNC 430, and one SRNC 440 are shown in FIG. 4, it should
be noted that any combination of wireless and wired devices may be
included in the wireless communication system 400.
[0033] FIG. 5 is a functional block diagram 500 of a WTRU 410 and
the Node-B 420 of the wireless communication system 400 of FIG. 4.
As shown in FIG. 5, the WTRU 410 is in communication with the
Node-B 420 and both are configured to perform a method for
selecting an RLC PDU size.
[0034] In addition to the components that may be found in a typical
WTRU, the WTRU 410 includes a processor 415, a receiver 416, a
transmitter 417, and an antenna 418. The processor 415 is
configured to perform a method for selecting an RLC PDU size. The
receiver 416 and the transmitter 417 are in communication with the
processor 415. The antenna 418 is in communication with both the
receiver 416 and the transmitter 417 to facilitate the transmission
and reception of wireless data.
[0035] In addition to the components that may be found in a typical
base station, the Node-B 420 includes a processor 425, a receiver
426, a transmitter 427, and an antenna 428. The receiver 426 and
the transmitter 427 are in communication with the processor 425.
The antenna 428 is in communication with both the receiver 426 and
the transmitter 427 to facilitate the transmission and reception of
wireless data.
[0036] Hereinafter, the terminology "transport block" may refer to
any of the following: a MAC-e PDU, MAC-i PDU, MAC-es PDU, a MAC-is
POLL or a MAC PDU. The terminology "number of bits in a transport
block" or "selected transport block (TB)" is used to refer to any
of the following quantities: the total size of the transport block
(or "transport block size"); the total size of the transport block,
minus the number of bits required for MAC header; the number of
bits available to the MAC-d flow or logical channel to which the
RLC PDU belongs, according to the E-DCH transport format
combination (E-TFC) selection procedure; the number of bits
available to a combination of MAC-d flows or logical channels,
according to the E-TFC selection procedure; and the number of bits
requested from the given logical channel as part of the E-TFC
selection procedure.
[0037] FIG. 6 is a block diagram of a method 600 for use in a
wireless transmit/receive unit (WTRU) for pre-generating a radio
link control (RLC) protocol data units (PDUs) for transmission in a
later TTI. Referring to FIG. 6, the WTRU performs the calculation
of RLC PDU size (or the size of the data field of the RLC PDU) and
creation of RLC PDUs at a predetermined time 610. The WTRU performs
the sewing grant update procedure, or uses the outcome of the
latest serving grant update 620. The WTRU calculates a "number of
bits in transport block" (G) 630 based on the outcome of the
serving grant update procedure and possibly other factors. The WTRU
may then calculate the RLC PDU size (S) 640 based on the number of
bits in transport block and possibly other factors and parameters.
The WTRU may then be configured to update the amount of data if
outstanding RLC PDUs 660. Next, the WTRU may be configured to
determine if additional RLC PDUs may be created based on the amount
of data in outstanding RLC PDUs determined, the amount of data in a
new RLC PDU if such RLC PDU would be created, and the limit on the
total amount of data in outstanding RLC PDUs 670. If the WTRU
determines that no additional RLC PDU may be created, the WTRU may
refrain from creating an RLC PDU and wait for the next time the
procedure will be executed. Otherwise, the WTRU may be configured
to create an additional RLC PDU 680. The WTRU may then be
configured to check if there is still available data (in RLC SDUs)
to create RLC PDUs from 690. If this is the case then the WTRU may
be configured to update the amount of data in outstanding RLC PDUs.
Otherwise the WTRU may be configured to wait for the next time the
procedure is executed. It should be noted that prior to restarting
the serving grant update procedure, to save time the WTRU may be
configured to check at this point if there is any available data to
create RLC PDUs from. If there is no data to create the WTRU may be
configured to could skip the wait for the next time of
execution.
[0038] The following embodiments, describing the time when the RLC
PDU size should be calculated (step 610), may be used in
"combination", in the sense that the calculation could take place
if any of these events takes place. In a first embodiment, the WTRU
may be configured to determine the RLC PDU size periodically, for
example, on a transmission time interval (TTI) basis, or every N
TTIs. The WTRU may also be configured to determine the RLC PDU size
every time E-TFC selection occurs. The WTRU may also be configured
to determine the RLC PDU size every time a new RLC PDU is created
from the segmentation and/or concatenation of RLC service data
units (SDUs). The WTRU may also be configured to determine the RLC
PDU size every time the RLC receives new data from higher layers
(i.e. new RLC SDUs), or every time the serving grant is updated.
The WTRU may also be configured to determine the RLC PDU size based
upon an active set update procedure. Optionally, the RLC PDU size
may be determined whenever the serving cell changes, or upon setup,
configuration or reconfiguration of the radio bearer, transport
channel or physical channel. The RLC PDU sizes may be calculated
upon reception of the minimum/maximum values from RRC
signaling.
[0039] Alternatively, the WTRU may be configured to determine the
RLC PDU size based on a triggering event. In one embodiment, the
WTRU may be configured to determine the RLC PDU size when changes
occur in the available number of bits in a transport block, the
E-DCH transport format combination index (E-TFCI), the WTRU power
headroom, or the serving grant. The amount of change necessary to
qualify as a triggering event may be based on a predetermined
threshold.
[0040] Alternatively, the WTRU may be configured to update the
information used in the calculation of the RLC PDU size at every
E-TFC selection in which data from this logical channel is included
in the MAC-i PDU. In another alternative the WTRU may be configured
to update the information used in the calculation of the RLC PDU
size at every E-TFC selection in which the HARQ processes are
configured to transmit scheduled data and/or non-scheduled if the
RLC entity is carrying scheduled flows or non-scheduled flows
respectively. Or the WTRU may be configured to update the
information used in the calculation of the RLC PDU size at every
E-TFC selection in which data from the MAC-d flow of the logical
channel is included in the MAC-i PDU or in which the MAC-d flow of
the logical channel is allowed to be multiplexed with.
[0041] Optionally, the WTRU may be configured to determine the RLC
PDU size when one of the following quantities changes by more than
a certain value, or becomes lower than a threshold, or becomes
higher than a threshold, the quantities including: 1) the measured
path loss, measured received signal code power (RSCP) or measured
common pilot channel (CPICH) Ec/No to the serving cell, and the
WTRU transmission power; 2) the error rate of the nth HARQ
transmission (for any n) or the average error rate over all HARQ
transmissions;) the HARQ transmission delay (time between the
initial transmission of the transport block and its successful
acknowledgment): 3) the total RLC PDU transmission delay (HARQ
transmission delay plus the time between RLC PDU creation and
transmission); 4) the residual HARQ error rate (i.e. the
probability that a HARQ failure occurs) or the number of HARQ
failures; 5) the percentage or number of RLC PDUs that have needed
retransmissions; 6) the downlink channel quality perceived by the
WTRU, or the reported channel quality indicator (CQI); 7) the
number or percentage of "UP" transmit power control (TPC) commands
received from the network within a certain time period, possibly
conditioned on the WTRU transmitting above a certain absolute
transmission power;) the number of RLC retransmissions required to
successfully transmit an RLC PDU) the percentage or number of RLC
SDUs that have been discarded; or 8) any function (e.g. average) of
one or a combination of the above quantities.
[0042] Alternatively, the WTRU may be configured to determine the
RLC PDU size when a hybrid automatic repeat request (HARQ) failure
occurs (all HARQ transmissions for a transport block fail), or
whenever the number or HARQ retransmission required for successful
delivery exceeds a threshold, or a configured number of such events
occurs. In another alternative, the WTRU may be configured to
calculate the RLC PDU size when an RLC PDU needs to be
retransmitted, or a configured number of RLC retransmissions occur
or a configured percentage of RLC PDUs are retransmitted. In yet
another embodiment, the RLC PDU size may be recalculated when an
RLC PDU exceeds the number of retransmission or the discard tinier
expires or a configured number or percent age of RLC PDU/SDUs are
discarded. The RLC PDU size may also Lie calculated when a timer
has expired. The value of this timer may be configurable. The RLC
PDU size may be calculated by the MAC layer and provided to the RLC
layer on a TTI basis or on a periodic basis. Alternatively, the RLC
layer may calculate the RLC PDU size based on information from the
MAC layer.
[0043] In one embodiment, the RLC PDU size is set to the "number of
bits in transport block" calculated in step 630, or is set to a
function thereof. In other words, the size of data field of the RLC
PDU is set so that the size of the complete RLC PDU (including the
header) matches the "number of bits in transport block". The size
may be re-adjusted if the value is higher than a maximum or lower
than a minimum as described later. The calculation of the "number
of bits in transport block" depends on whether the logical channel
which the RLC PDU belongs to belongs to a scheduled flow or a
non-scheduled flow.
[0044] For logical channels that belong to scheduled flows, the
"number of hits in a transport block" may refer to the highest
payload that may be transmitted based on the scheduled (serving)
grant and available power, (for example, the WTRU uses the
Min{Maximum E-TFC that can be sent by the WTRU according to E-TFC
restriction procedure, the highest payload that could be
transmitted according to the serving grant and the selected power
offset}); the highest pay load that could be transmitted according
to the serving grant only; the highest payload that could be
transmitted according to the serving grant and selected power
offset, without taking into consideration the required transmit
power versus the maximum WTRU transmit power (i.e. assuming that
the available WTRU transmit power is always sufficient); and the
highest payload that could be transmitted considering the scheduled
grant (SG) and maximum WTRU transmit power, (for example, the WTRU
uses the Min{Maximum E-TFC that can be sent by the WTRU according
to E-TFC restriction procedure. Highest payload that could be
transmitted according to the serving grant, without taking into
consideration the selected power offset}). The "highest payload
that could be transmitted according to the serving grant" may also
be referred to as the "maximum amount of data allowed to be
transmitted by the applicable current grant for the current
TTI".
[0045] The "number of bits in a transport block" may include any of
the combinations described above minus the size of the MAC-i/is
header. It may also include any of the combinations described above
minus the size of the scheduling information (SI) field, if this
field is transmitted.
[0046] When referred to hereafter, the selected power offset
corresponds to the power offset from the HARQ profile of the MAC-d
flow that allows highest priority data to be transmitted, or in the
case where more than one MAC-d flow allows data of the same highest
priority to be transmitted it corresponds to the power offset of
the MAC-d flow selected by implementation. Alternatively, the power
offset can refer to the power offset from the HARQ profile of the
MAC-d flow to which the logical channel belongs to.
[0047] When referred to hereafter the value of scheduled grant (SG)
may refer to the Serving_Grant value provided by the Serving Grant
Update function or alternatively to the scaled down serving grant
in the ease where 10 ms TTI is configured and the TTI for the
upcoming transmission overlaps with a compressed mode gap.
[0048] In the case of initial transmission where no E-TFC selection
has been performed yet or if no E-TFC selection has taken place for
a given amount of time the WTRU may perform one or a combination,
of the following: 1) for logical channels belonging to a scheduled
flow--Use the value of the Information Element (IE) "Serving Grant
value" if provided in the RRC message. This IE is provided by the
network end it is used as an initial grant when E-DCH is
configured, otherwise the serving grant, is initially set to zero.
2) For logical channels belonging to a non-scheduled flow--the WTRU
can simply use the non-serving grant as an initial value to start
creating RLC PDUs. 3) When no initial Serving Grant is configured
(i.e. IE "Serving Grant value" is not provided) or alternatively
always for the above mentioned situation, the size of the RLC PDU
can be determined using one or a combination of the following
values: i) determine size and create RLC PDU at last minute for the
current and next TTI(s) only for initial transmission, using the
current E-TFC or "number of bits in a transport block" (i.e.
determined at the given TTI); ii) RLC PDU size is determined to be
of minimum RLC PDU size, or multiple of minimum size, or maximum
RLC PDU or max/N; 4) the RLC PDU size is chosen from of the minimum
set E-TFC sizes. For instance, the WTRU may choose the smallest
value allowed or the largest value. 5) RLC uses a pre-configured
value specified by the network or configured in the WTRU.
[0049] In an alternative embodiment, the "number of bits in a
transport block" may be one or any combination of: 1) the "number
of bits in a transport block" which will contain the RLC PDU being
created (this would imply that the UE never creates more RLC PDUs
than what can be delivered at the current TTI); 2) the "number of
bits in a transport block" resulting from an E-TFC selection
determined one or more TTI's earlier. The number of TTI's the
transport block (TB) size is determined in advance may be
configurable or may be based on WTRU capabilities. 3) The average
of the "number of bits in a transport blocks" resulting from E-TFC
selection that have been calculated in earlier or this TTI. In this
case the resulting TB size may be quantized to match an allowed
E-TFC size. The averaging period may be configurable. 4) The
"number of bits in a transport block" that may be transmitted if
E-TFC selection took place at the time of calculation (even if it
is not actually taking place), given certain assumed conditions in
terms of serving grant, WTRU power headroom, non-scheduled grants,
and other parameters used during E-TFC selection procedure. These
assumed conditions may be based on: i) the currently prevailing
values of the serving grant, WTRU power headroom, non-scheduled
grants, and other parameters; ii) values of the serving grant, WTRU
power headroom, non-scheduled grants, and other parameters, that
have been experienced in the past; iii) values or the serving
grant, WTRU power headroom, non-scheduled grants, and other
parameters, that are expected to be realized in the near future
given certain measurements (such as path loss, CPICH Ec/No, CPICH
RSCP, WTRU transmission power, downlink channel quality, etc.); or
iv) any combination or function of the above. 5) The "number of
bits in a transport block" as per one of the above definitions, or
average thereof, multiplied by a factor and rounded up or down to
the next integer or to the closest value from a finite set of
possible values. The factor may be larger than 1 or smaller than 1.
6) The "number of bits in a transport block" as per one of the
above definitions, or average thereof, multiplied by a "maximum
number of MAC segments per RLC PDU" parameter which is either
signaled or pre-determined (the actual parameter name could be
different); 7) the "number of bits in a transport block" as per one
of the above definitions, or average thereof, divided by a "maximum
number of MAC-is SDU's per MAC-i PDU" parameter which is either
signaled or pre-determined, or an equivalent parameter (the actual
parameter name could be different); and 8) any function of the
above.
[0050] The WTRU may he configured with a minimum size and a maximum
size restriction for each RLC PDU. If the RLC PDU size obtained
using one of the methods described above is higher than the
configured maximum size, then the RLC PDU size is reset to this
configured maximum size. Similarly, if the RLC PDU size obtained
using one of the methods described above is lower then the
configured minimum size, then the RLC PDU size is reset to this
configured minimum size.
[0051] In one embodiment, the UTRAN 300 may determine the maximum
RLC PDU size and communicates the maximum RLC PDU sixe value to the
WTRU 200 using L2 or L3 (RRC) signaling. For example, the UTRAN 300
may configure the WTRU 200 to use a minimum RLC PDU size and a
maximum RLC PDU size using the RRC information element (IE) "RLC
info." The signaling of the maximum RLC PDU size value may occur
upon radio bearer configuration or radio bearer reconfiguration.
Further, the signaling of the maximum RLC PDU size value may occur
upon transport channel configuration or transport channel
reconfiguration.
[0052] Alternatively, the WTRU may be configured to derive the
minimum RLC PDU size from a minimum allowed MAC segment size, if
such size is defined. For example, the minimum RLC PDU size may be
a multiple of a minimum MAC segment size. Alternatively, the
minimum RLC PDU size may be a static value that is preconfigured in
the WTRU 200.
[0053] Referring back to FIG. 6, the WTRU may be configured to
create a limited number of RLC PDUs. For example in (650), the WTRU
determines a limit on the amount of data in RLC PDUs already
created but not yet transmitted (i.e. not yet inserted into a
transport block). These PDUs are referred to as "outstanding" RLC
PDUs hereafter. Optionally, the amount of data in outstanding RLC
PDUs may also include the content of the segmentation entity for
the corresponding logical channel. In one embodiment, the WTRU may
be configured to create a limited number of new RLC PDUs, such that
the total amount of data in outstanding RLC PDUs does not exceed
the predetermined limit. It should be noted that the number of new
RLC PDUs created may be zero if the amount of data in outstanding
RLC PDUs was already exceeding the limit at the beginning of the
procedure. In this case, the WTRU does not create additional RLC
PDUs, hut does not discard already created RLC PDUs. The
predetermined data limit may be pre-defined, signaled by higher
layers, or based on the current E-TFC or current number of bits in
a transport block for the logical channel (as indicated by the MAC
layer), or size of new RLC PDUs that would be created. In one
embodiment, the limit in step may correspond to the amount of data
that could be transmitted from tins logical channel, multiplied by
a pre-defined factor given current gram and power conditions. In
other words, the limit corresponds to the maximum o mount of data
allowed to be transmitted by the applicable current grant
(scheduled or non-scheduled) for the current TTI, which has been
calculated in step 630.
[0054] Alternatively, the WTRU may he configured to create as many
new RLC PDUs as possible given the amount of buffered data (RLC
SDUs). Or the WTRU may be configured to create a maximum number
(Nc) of new RLC PDUs (up to the number possible given the amount of
buffered data). This maximum number may be pre-defined, signaled by
higher layers, or based on the current E-TFC or current number of
hits in a transport block for this logical channel (as indicated by
the MAC layer).
[0055] In another alternative, the WTRU may be configured to create
a limited number of new RLC PDUs based on a predefined amount of
data expressed in bits or bytes. This amount may he pre-defined,
signaled by higher layers, or based on the current E-TFC or current
number of bits in a transport block for this logical channel or
MAC-d flow (as indicated by the MAC layer). For instance, the
amount may correspond to the amount of data that could be
transmitted from this logical channel or MAC-d flow (times a
factor) given current grant or power conditions.
[0056] Optionally, logical channels which belong to non-scheduled
flows may not have any restrictions on the number of PDUs they
create in advance. This may be the case when the RLC PDU size
determination is based on the value of the non-serving grant only.
In this scenario, RLC PDUs of size corresponding to the non-serving
grant (optionally minus the MAC header part) can always be
created.
[0057] FIG. 7 shows an example of a combination of embodiments for
the various steps described in FIG. 6. The different steps shown
are achieving the same tasks as the corresponding steps in FIG. 6,
but are more specific.
[0058] In step 740 corresponding to step 740, the RLC PDU size S is
determined as the maximum between a minimum RLC PDU size and the
minimum between a maximum RLC PDU size and the number of bits in
transport block (G) determined in step 730 (corresponding to stop
630). In step 750, the maximum amount of data in outstanding PDUs
(M) is calculated as a constant (such as 4) times the number of
bits in transport block (G) determined in step 730. In step 770,
the maximum amount of data in outstanding PDUs (M) is compared to
the sum of the amount of data in outstanding PDUs (D) and the size
S determined in step 740. Alternatively, it could be also compared,
to the sum of D and a size T<S, if there is not enough available
data in RLC SDUs to create an additional RLC PDU of size S. In step
710, the WTRU waits until the next TTI before executing the
procedure the next time.
[0059] Although features and elements are described above in
particular combinations, each feature or element can be used alone
without the other features and elements or in various combinations
with or without other features and elements. The methods or flow
charts provided herein may be implemented in a computer program,
software, or firmware incorporated in a computer-readable storage
medium for execution by a general purpose computer or a processor.
Examples of computer-readable storage mediums include a read only
memory (ROM), a random access memory (RAM), a register, cache
memory, semiconductor memory devices, magnetic media such as
internal hard disks and removable disks, magneto-optical media, and
optical media such as CD-ROM disks, and digital versatile disks
(DVDs).
[0060] Suitable processors include, by way of example, a general
purpose processor, a special purpose processor, a conventional
processor, a digital signal processor (DSP), a plurality of
microprocessors, one or more microprocessors in association with, a
DSP core, a controller, a. microcontroller, Application Specific
Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs)
circuits, any other type of integrated circuit (IC) and/or a state
machine.
[0061] A processor in association with software may be used to
implement a radio frequency transceiver for use in a wireless
transmit receive unit (WTRU), user equipment (UE), terminal, base
station, radio network controller (RNC), or any host computer. The
WTRU may be used in conjunction with modules, implemented in
hardware and/or software, such as a camera, a video camera module,
a videophone, a speakerphone, a vibration device, a speaker, a
microphone, a television transceiver, a hands free headset, a
keyboard, a Bluetooth.RTM. module, a frequency modulated (FM) radio
unit, a liquid crystal display (LCD) display unit, an organic
light-emitting diode (OLED) display unit, a digital music player, a
media player, a video game player module, an Internet browser,
and/or any wireless local area network (WLAN) or Ultra Wide Band
(UWB) module.
* * * * *