U.S. patent application number 14/701954 was filed with the patent office on 2015-08-20 for method and apparatus for creating an enhanced medium access control packet data unit for enhanced transport format combination selection in wireless communications.
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 Christopher R. Cave, Paul Marinier, Diana Pani, Stephen E. Terry.
Application Number | 20150237528 14/701954 |
Document ID | / |
Family ID | 40508208 |
Filed Date | 2015-08-20 |
United States Patent
Application |
20150237528 |
Kind Code |
A1 |
Terry; Stephen E. ; et
al. |
August 20, 2015 |
METHOD AND APPARATUS FOR CREATING AN ENHANCED MEDIUM ACCESS CONTROL
PACKET DATA UNIT FOR ENHANCED TRANSPORT FORMAT COMBINATION
SELECTION IN WIRELESS COMMUNICATIONS
Abstract
Efficient enhanced transport format combination (E-TFC)
selection methods and apparatus support flexible radio link control
(RLC) packet data unit (PDU) size and medium access control (MAC)
layer segmentation. Methods for filling an enhanced medium access
control (MAC-e) packet data unit (PDU) with data from logical
channels as part of E-TFC selection are provided. In one
embodiment, the E-TFC selection algorithm employs a single request
from the MAC layer to the RLC layer to request the number of bits
it is allowed to send for a logical channel to create enhanced
MAC-e PDUs. In another embodiment, the MAC entity performs multiple
requests to the RLC entity. In another embodiment, the MAC entity
makes a single request to the RLC entity to create one or more
enhanced MAC-e PDUs of a set size. A technique is also provided for
maintaining a guaranteed bit rate (GBR) for non-scheduled data
flows with variable-length headers.
Inventors: |
Terry; Stephen E.;
(Northport, NY) ; Marinier; Paul; (Brossard,
CA) ; Pani; Diana; (Montreal, CA) ; Cave;
Christopher R.; (Dollard-des-Ormeaux, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InterDigital Patent Holdings, Inc. |
Wilmington |
DE |
US |
|
|
Assignee: |
InterDigital Patent Holdings,
Inc.
Wilmington
DE
|
Family ID: |
40508208 |
Appl. No.: |
14/701954 |
Filed: |
May 1, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13444727 |
Apr 11, 2012 |
9059875 |
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14701954 |
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12239097 |
Sep 26, 2008 |
8179877 |
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13444727 |
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60975955 |
Sep 28, 2007 |
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60976319 |
Sep 28, 2007 |
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Current U.S.
Class: |
370/328 |
Current CPC
Class: |
H04W 28/065 20130101;
H04W 72/1263 20130101; H04L 29/02 20130101; H04L 47/365 20130101;
H04L 69/22 20130101; H04W 28/0268 20130101 |
International
Class: |
H04W 28/06 20060101
H04W028/06; H04L 29/06 20060101 H04L029/06; H04W 28/02 20060101
H04W028/02; H04L 12/805 20060101 H04L012/805 |
Claims
1. A method for creating an enhanced medium access control (MAC-e)
packet data unit (PDU) associated with enhanced transport format
combination (E-TFC) selection, the method comprising: determining
that a segment of a first radio link control (RLC) PDU associated
with a first logical channel is available for transmission, wherein
the segment is remaining from a previous transmission; on a
condition that a size of the segment and a corresponding header
does not exceed a determined size, including the segment and the
corresponding header in the enhanced MAC-e PDU; on a condition that
a size of the segment and a corresponding header exceeds the
determined size re-segmenting the segment into a first sub-segment
and a second sub-segment, including the first sub-segment and a
corresponding header in the enhanced MAC-e PDU, and storing the
second sub-segment for a next transmission; and transmitting the
enhanced MAC-e PDU.
2. The method of claim 1, further comprising: on a condition that a
second RLC PDU and a corresponding header are included in the
enhanced MAC-e PDU, and size of the second RLC PDU and the
corresponding header exceeds the determined size: dividing the
second RLC PDU into a first segment and a second segment; and
including the first segment and a corresponding header in the
enhanced MAC-e PDU, and storing the remaining second segment for a
next transmission.
3. The method of claim 2, wherein the second RLC PDU is associated
with the first logical channel.
4. The method of claim 2, wherein the determined size is a minimum
of a remaining available payload or a remaining granted
payload.
5. The method of claim 1, wherein the first logical channel is a
highest priority logical channel.
6. The method of claim 2, wherein the second RLC PDU and the
corresponding header are included in the enhanced MAC-e PDU.
7. A wireless transmit/receive unit (WTRU) comprising: a processor
configured to at least: determine that a segment of a first radio
link control (RLC) packet data unit (PDU) associated with a first
logical channel is available for transmission, wherein the segment
is remaining from a previous transmission; on a condition that size
of the segment and a corresponding header does not exceed a
determined size, include the segment and the corresponding header
in an enhanced medium access control (MAC-e) PDU; on a condition
that size of the segment and a corresponding header exceeds the
determined size re-segment the segment into a first sub-segment and
a second sub-segment, including the first sub-segment and the
corresponding header in the enhanced MAC-e PDU, and store the
remaining second sub-segment for a next transmission; and a
transmitter configured to transmit the enhanced MAC-e PDU.
8. The WTRU of claim 7, further comprising: on a condition that a
second RLC PDU and a corresponding header are included in the
enhanced MAC-e PDU, and size of the second RLC PDU and the
corresponding header exceeds the determined size: divide the second
RLC PDU into a first segment and a second segment; and include the
first segment and a corresponding header in the enhanced MAC-e PDU,
and storing the remaining second segment for a next
transmission.
9. The WTRU of claim 8, wherein the second RLC PDU is associated
with the first logical channel.
10. The WTRU of claim 8, wherein the determined size is a minimum
of a remaining available payload or a remaining granted
payload.
11. The WTRU of claim 7, wherein the first logical channel is a
highest priority logical channel.
12. The WTRU of claim 8, wherein the second RLC PDU and the
corresponding header are included in the enhanced MAC-e PDU.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 13/444,727, filed on Apr. 11, 2012, which is a
divisional of U.S. patent application Ser. No. 12/239,097, filed
Sep. 26, 2008, which issued as U.S. Patent Application No.
8,179,877 on May 15, 2012; which claims the benefit of U.S.
Provisional Application No. 60/975,955 filed Sep. 28, 2007, and
U.S. Provisional Application No. 60/976,319 filed on Sep. 28, 2007,
the contents of which are incorporated by reference herein.
FIELD OF INVENTION
[0002] This application is related to wireless communications.
BACKGROUND
[0003] Wireless communication systems following Universal Mobile
Telecommunications Systems (UMTS) technology, were developed as
part of Third Generation (3G) Radio Systems, and is maintained by
the Third Generation Partnership Project (3GPP). A typical UMTS
system architecture in accordance with current 3GPP specifications
is depicted in FIG. 1. The UMTS network architecture includes a
Core Network (CN) interconnected with a UMTS Terrestrial Radio
Access Network (UTRAN) via an Iu interface. The UTRAN is configured
to provide wireless telecommunication services to users through
wireless transmit/receive units (WTRUs), referred to as user
equipments (UEs) in the 3GPP standard, 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 has 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 UEs. Uplink
(UL) communications refer to transmissions from UE to Node B, and
downlink (DL) communications refer to transmissions from Node B to
UE. One or more Node Bs are connected to each RNC via an Iub
interface; RNCs within a UTRAN communicate via an Iur
interface.
[0004] According to 3GPP standard Release 6 for high speed uplink
packet access (HSUPA), the MAC layer multiplexes higher layer data
into MAC-e PDUs. In a transmission time interval (TTI), the MAC
layer sends one MAC-e PDU to the PHY layer to be transmitted over
the enhanced dedicated channel (E-DCH) dedicated physical data
control channel (E-DPDCH). As part of link adaptation, the MAC
layer performs enhanced transport format combination (E-TFC)
selection based on radio link control (RLC) logical channel
priority, RLC buffer occupancy, physical channel conditions,
serving grants, non-serving grants, power limitations, hybrid
automatic repeat request (HARQ) profile and logical channel
multiplexing.
[0005] As part of the E-TFC selection function, the UE initially
identifies the highest priority higher layer MAC-d flow that has
data to be transmitted. The UE then identifies the MAC-d flow(s)
which are allowed to be multiplexed with this MAC-d flow and whose
grants allow them to transmit in the current TTI. Based on the HARQ
profile of the selected MAC-d flow, the UE identifies the power
offset to use for transmission. Based on this power offset and the
E-TFC restriction procedure, the MAC determines the maximum
supported MAC-e PDU size or E-TFC that can be sent by the UE,
called the maximum supported payload, for the upcoming
transmission, based only on available power, without taking into
account available serving and/or non-serving grants. The E-TFC
selection algorithm then determines the largest amount of data,
called the scheduled payload, that can be transmitted based on the
serving grant and the selected power offset. In the case of
non-scheduled flows, the E-TFC selection algorithm takes into
account the non-scheduled grant to determine a non scheduled
payload. The total granted payload is equivalent to the determined
scheduled and non-scheduled payload, and is defined as the amount
of data that the UE is allowed to transmit based on serving and
non-scheduled grants. However, due to the fact that the UE may have
limited power, the available amount of data that the UE can
transmit (available payload) is the equivalent of the minimum value
between the maximum supported payload and the total granted
payload.
[0006] Once the available payload is determined, the MAC layer
requests data from the logical channels corresponding to the MAC-d
flows that are allowed to be multiplexed in the current TTI in
order of priority. When all the data to fill a MAC-e PDU according
to the available payload is available, or when no more RLC data is
available, the MAC-e PDU is sent to the physical layer to be
transmitted over the E-DPDCH with the selected beta factor, which
is a gain factor.
[0007] According to 3GPP standard Release 6, the radio link control
(RLC) layer in acknowledged mode (AM) can only operate using fixed
RLC protocol data unit (PDU) sizes. In addition, the high-speed
medium access control (MAC-hs) entity in the Node B and the medium
access control (MAC-e/es) entity in the UE do not support
segmentation of the service data units (SDUs) from higher layers.
These restrictions may result in performance limitations,
especially as high speed packet access (HSPA) evolves towards
higher data rates. In order to reach higher data rates and reduce
protocol overhead and padding, a number of new features were
introduced to the layer 2 (L2) protocol in 3GPP Release 7. In
particular, flexible RLC PDU sizes and MAC segmentation in the
downlink were introduced. However, corresponding L2 enhancements
were not introduced for uplink operation in 3GPP Release 7.
[0008] More recently, a new 3GPP work item has been proposed for
Improved L2 Uplink to introduce enhancements to L2 operation in the
uplink. Some of the objectives of Improved L2 Uplink include:
support for flexible RLC PDU sizes; support for MAC segmentation of
higher layer PDUs including MAC-d and MAC-c PDUs; smooth transition
between old and new protocol formats; and support for seamless
state transitions between the CELL_DCH, CELL_FACH, CELL_PCH and
URA_PCH states, dependent on potential enhancements to the
CELL_FACH uplink transmission.
[0009] The current E-TFC selection algorithm is designed for
current 3GPP standards releases, including Release 7 or earlier,
and the current enhanced dedicated channel (E-DCH) functionalities,
which require fixed RLC PDU sizes. It is recognized that current
E-TFC selection algorithm for Release 7 or earlier will result in
inefficient creation of MAC-e/es PDUs under the proposed Improved
Layer 2 Uplink because the current E-TFC selection algorithm is not
designed to take into account flexible RLC PDU sizes for every
logical channel, segmentation of RLC PDUs, and flexible header
format size based on the amount of RLC PDUs in a enhanced MAC-es
PDU.
[0010] Therefore, a new E-TFC selection function that takes into
consideration the additional functionalities including flexible RLC
PDU size, segmentation of RLC PDUs and flexible header format size
when creating a MAC-e PDU with optimal RLC PDU sizes is
desired.
SUMMARY
[0011] Methods and apparatus for enhanced transport format
combination (E-TFC) for uplink wireless communications are
disclosed. The proposed techniques for E-TFC selection support
flexible radio link control (RLC) packet data unit (PDU) size as
well as medium access control (MAC) layer segmentation of MAC-d
PDUs. Accordingly, RLC PDUs are created to properly fit into
selected E-TFC transport block sizes. Based on the selected E-TFC,
the MAC entity and RLC entity work together to create RLC PDU sizes
on a transmission time interval (TTI) basis to maximize the amount
of data to be transmitted and reduce the amount of overhead between
the RLC and MAC protocols.
[0012] Methods for filling an enhanced MAC-e packet data unit (PDU)
with data from logical channels as part of E-TFC selection are
provided. In one embodiment, the E-TFC selection algorithm uses a
single request from the MAC layer to the RLC layer to request the
number of bits it is allowed to send for a logical channel to
create one or more PDUs of possibly different sizes. In another
embodiment, the MAC entity performs multiple requests to the RLC
entity. In another embodiment, the MAC entity makes a single
request to the RLC entity to create one or more PDUs of a set size.
A technique is also provided for maintaining a guaranteed bit rate
(GBR) for non-scheduled data flows with variable-length
headers.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] A more detailed understanding may be had from the following
description, given by way of example in conjunction with the
accompanying drawings wherein:
[0014] FIG. 1 shows an overview of the system architecture of a
conventional Universal Mobile Telecommunications Systems (UMTS)
network;
[0015] FIG. 2 shows a block diagram of an enhanced MAC-e/es entity
in accordance with the teaching herein;
[0016] FIGS. 3A and 3B show a flow diagram of a procedure for
filling an enhanced MAC-e packet data unit (PDU) with data from
logical channels as part of E-TFC selection in accordance with one
embodiment;
[0017] FIG. 4 shows a flow diagram of a procedure for filling an
enhanced MAC-e PDU with data from logical channels as part of E-TFC
selection in accordance with another embodiment;
[0018] FIG. 5 shows a flow diagram of a procedure for filling an
enhanced MAC-e PDU with data from logical channels as part of E-TFC
selection in accordance with another embodiment; and
[0019] FIG. 6 shows a flow diagram of a simplified procedure for
filling an enhanced MAC-e PDU with data from logical channels as
part of E-TFC selection in accordance with another embodiment.
DETAILED DESCRIPTION
[0020] When referred to hereafter, the terminology "wireless
transmit/receive unit (WTRU)" includes but is not limited to 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.
[0021] Efficient enhanced transport format combination (E-TFC)
selection algorithms are provided that take into account the new
functionalities added to the Layer 2 protocol as part of the
proposed 3GPP Improved Layer 2 (L2) Uplink work item. The proposed
embodiments for E-TFC selection describe the sequence of events a
WTRU may follow when it has to fill an enhanced MAC-e packet data
unit (PDU) with data from one or more radio link control (RLC)
logical channels or MAC-d and MAC-c data flows. The proposed
embodiments for E-TFC selection may be used individually or in any
combination. While E-TFC selection is described as being performed
by a WTRU or UE for uplink communications, the teachings herein may
be applied to both downlink and uplink communications and may be
performed by a base station, Node B, or Node B in combination with
a radio network controller (RNC).
[0022] Herein, enhanced MAC-e, enhanced MAC-es, and enhanced
MAC-e/es are used to represent enhanced versions of existing medium
access control (MAC) protocols in high speed packet access (HSPA),
including, but not limited to, MAC-e, MAC-es and MAC-e/es. The
Remaining Available Payload refers to the maximum amount of data
that can be transmitted due to the available grant, including
serving and non-serving grant, the available power, the selected
power offset and scheduling information. The Remaining Granted
Payload refers to the Remaining Non-Scheduled Payload when a
non-scheduled MAC-d flow is being processed and to the Remaining
Scheduled Payload for scheduled MAC-d flows. Herein, the function
MINA, B) returns the minimum value from among the parameters A and
B in terms of number of bits.
[0023] A higher layer PDU refers to a MAC-d PDU, a MAC-c PDU, or an
RLC PDU. MAC-d, MAC-c and RLC PDUs may be treated equivalently in
the proposed embodiments herein. An RLC PDU belongs to a dedicated
logical channel and is forwarded to the MAC-d entity. The MAC-d
entity then forwards the data to the enhanced MAC-es entity. The
output of the MAC-d is called a MAC-d PDU. A MAC-d PDU includes
data received from the dedicated control channel (DCCH) or the
dedicated traffic channel (DTCH) logical channels, while a MAC-c
PDU includes data received from common channels such as the common
control channel (CCCH). For convenience, some of the embodiments
herein may be described with reference to RLC PDUs, however, the
embodiments are equally applicable to MAC-d or MAC-c PDUs and have
the same functionality for RLC, MAC-d and MAC-c PDUs.
[0024] FIG. 2 shows a block diagram of an enhanced MAC-e/es entity
200 in accordance with the teaching herein. The enhanced MAC-e/es
entity 200 multiplexes logical channel data from higher layers
entities, including the MAC-d, MAC-c, and radio link control (RLC)
entities, into enhanced MAC-e PDUs and provides them in the form of
transport blocks (TBs) to the physical (PHY) layer entity. The
enhanced MAC-e/es entity 210 may include the following entities: a
hybrid automatic repeat request (HARQ) entity 222, a segmentation
entity 214, which may contain a segmentation buffer 216, a
multiplexer and TSN setting entity 218, a scheduling entity 220,
and an enhanced transport format combination (E-TFC) selection
entity 212.
[0025] The HARQ entity 222 is responsible for handling MAC layer
functions relating to the HARQ protocol for error correction,
including storing and retransmitting enhanced MAC-e payloads. The
segmentation entity 214 segments higher layer PDUs when they are
too large to fit into the enhanced MAC-e PDU and sends the segment
to multiplexer 218. The remaining segment is stored in the
segmentation buffer 216. The multiplexer and TSN setting entity 218
is responsible for concatenating multiple enhanced MAC-es SDUs,
which include segmented or complete higher layer PDUs, into
enhanced MAC-es PDUs. The multiplexer and TSN setting entity 218
also multiplexes multiple enhanced MAC-es PDUs from the multiplexed
logical channels into enhanced MAC-e PDUs to be provided to the PHY
layer for transmission in the next transmission time interval (TTI)
as instructed by the E-TFC selection entity 212. The scheduling
entity 220 is responsible for routing associated uplink signaling.
The E-TFC selection entity 212 determines how much data can be sent
in a TTI based on scheduling information, Relative Grants (RGs),
Absolute Grants (AGs), and Serving Grants (SGs) and available power
resources and determines E-TFC restriction, which is used to
determine the maximum available data the UE can transmit based on
available power. E-TFC selection entity 212 also controls
multiplexer 218.
[0026] In one embodiment, the E-TFC selection algorithm employs a
single request from the MAC layer to the RLC layer. The enhanced
MAC entity requests from the logical channel the number of bits it
is allowed to send for that logical channel in a single request.
Based on the indicated number of bits, the number of available data
bits, and the number of new and retransmitted data bits, the RLC
entity creates or delivers RLC PDUs to fit into an enhanced MAC-e
PDU. Based on the E-TFC restriction, scheduled grant, non-scheduled
grant for all MAC-d flows, and scheduling information, the WTRU
determines the maximum amount of data that can be transmitted,
referred to as the Remaining Available Payload. The Remaining
Available Payload may account for the quantization loss for
scheduled transmission when filling up the enhanced MAC-e PDU with
logical channel bits. Once the Remaining Available Payload is
calculated, if a Scheduling Information needs to be transmitted, it
is subtracted from the Remaining Available Payload.
[0027] The E-TFC selection algorithm creates an enhanced MAC-e PDU
according to one or more of the following rules, which may be used
alone or in combination, for each logical channel. According to one
rule, the bits in the segmentation buffer have transmission
priority over other RLC PDUs of the logical channel being
processed. According to another rule, if a segment in the
segmentation entity is larger than the maximum amount of data to be
transmitted for that logical channel, the WTRU may re-segment the
MAC segment and send the maximum amount of data it can in the
enhanced MAC-e PDU, taking into consideration the enhanced MAC-e/es
header.
[0028] According to another rule, any remaining segment is stored
in the segmentation buffer. According to another rule, if there is
no segment in the segmentation buffer, or if there is still
available space in the enhanced MAC-e PDU after a segment is added,
the MAC entity can request from the logical channel the maximum
number of bits it is allowed to transmit, as determined by the
Remaining Available Payload and Remaining Granted Payload minus the
size of any added segment including any MAC header bits required to
transmit that segment if a segment was added. The RLC entity may
then provide one or more new RLC PDUs of a optimally chosen size
and/or one or more retransmitted RLC PDUs up to, or greater than,
the requested number of bits.
[0029] According to another rule, a higher layer PDU, which may be
an RLC MAC-d or MAC-c PDU, may be segmented by the segmentation
entity when the last of the RLC PDU(s) provided would exceed the
maximum allowed or available number of bits for that logical
channel or MAC-d flow, while taking into account space required for
MAC headers.
[0030] According to another rule, the amount of data to be
transmitted and corresponding enhanced MAC-e/es headers may not
exceed the maximum allowed number of bits, which is the Available
Remaining Payload or the Available Granted Payload, for that
logical channel, as indicated by the grant and/or the E-TFC
restriction. Due to the fact that the enhanced MAC-e/es header is
flexible and depends on the number of RLC PDUs in an enhanced
MAC-e/es service data unit (SDU), the E-TFC selection entity must
also take into consideration the additional header to be added with
any additional enhanced MAC-es SDUs. This can be taken into account
in the initial request to the RLC performed by the enhanced
MAC-e/es entity. For example, the enhanced MAC-e/es may assume that
K RLC PDUs will be received for the amount of remaining available
bits. Accordingly, the enhanced MAC-e/es may calculate the number
of bits to be requested according to the following calculation:
Number of bits to be requested=(available bits that can be
transmitted)-K.times.(additional number of header bits per RLC
PDU)-(fixed number header bits for the logical channel).
Alternatively, the RLC entity can take into consideration the
number of additional header bits that would be required for each
new RLC PDU created and the MAC just requests the available amount
of bits from the logical channel. For example, after receiving the
MAC request, for every new RLC PDU created or transmitted, the RLC
entity may subtract the additional header bits from the total
remaining bits it needs to forward to the enhanced MAC-e/es.
[0031] FIGS. 3A and 3B show a flow diagram of a procedure 300 for
filling an enhanced MAC-e PDU with data from logical channels as
part of E-TFC selection in accordance with the rules listed above
according to one embodiment. In FIGS. 3A and 3B, h1 refers to the
number of header bits needed per enhanced MAC-es PDU and h2 refers
to the number of header bits needed for the enhanced MAC-e header
per enhanced MAC-es SDU.
[0032] In step 305, in each TTI, each logical channel that is
allowed to transmit and satisfying multiplexing restrictions in the
current TTI is evaluated in order of priority. In step 310, it is
determined if the segmentation buffer contains bits or a segment to
be transmitted. If the segmentation buffer contains bits or a
segment to be transmitted, then in step 315 it is determined if the
number bits in the segment plus a corresponding enhanced MAC-e/es
header of h1+h2 bits is greater than MIN(Remaining Available
Payload, Remaining Granted Payload). If step 315 is true, then in
step 320 the segment is further segmented to produce a sub-segment
with a number of bits equal to MIN(Remaining Available
Payload--(h1+h2), Remaining Granted Payload--(h1+h2)). In step 325,
the sub-segment and corresponding enhanced MAC-e/es header are
added to the enhanced MAC-e PDU and the number of bits added is
subtracted from the Remaining Granted Payload and Remaining
Available Payload. The number of bits added is equal to the number
of bits in the sub-segment+h1+h2. If, in step 328, it is determined
that there is no more space available in the enhanced MAC-e PDU or
that the Remaining Available Payload is zero, then procedure 300
ends. Otherwise, procedure 300 returns to step 305 to repeat the
procedure for the next logical channel.
[0033] If, as determined in step 315, the number bits in the
segment+h1+h2 is less than MIN(Remaining Available Payload,
Remaining Granted Payload), then in step 330 the segment and
corresponding enhanced MAC-e/es header is added to the enhanced
MAC-e PDU and the number of bits added is subtracted from the
Remaining Granted Payload and Remaining Available Payload. The
number of bits added is the number of bits in the segment+h1+h2. In
step 335, if there is still space in the enhanced MAC-e PDU, then
MIN(Remaining Available Payload, Remaining Granted Payload) bits
are requested from the RLC logical channel. Additionally, bits may
be requested from the RLC logical channel when the Remaining
Granted Payload is greater than 0 and there is still space in the
enhanced MAC-e PDU.
[0034] Optionally, the enhanced MAC-e/es header may be taken into
account in the request to the RLC entity or by the RLC entity. More
specifically, the RLC entity may take into account only the
enhanced MAC-e header to be added per RLC PDU. When calculating the
size of the RLC PDUs to be created, the UE subtracts the enhanced
MAC-e header part, h2, for each RLC PDU it creates or retransmits
from the available number of bits requested. Alternatively, the RLC
entity may also take into account that one enhanced MAC-es header
will be added for all RLC PDUs submitted to the enhanced MAC
entity. Thus, initially, the RLC entity subtracts h1 from the
requested number of bits, and then continues the creation of RLC
PDUs, where it also takes into account N per RLC PDU created.
However, since the RLC entity is not aware if the enhanced MAC
entity had a segment to add from that logical channel and if the
enhanced MAC-es header part for that logical channel has already
been taken into account, it is preferable that the enhanced MAC
entity takes into account the enhanced MAC-es header prior to
requesting data from a logical channel.
[0035] If it was determined in step 310 that there are no bits to
be transmitted in the segmentation buffer, then in step 340 a
number of bits equal to MIN(Remaining Granted Payload, Remaining
Available Payload) are requested from the RLC logical channel.
Optionally, prior to requesting data from that logical channel, the
enhanced MAC entity may subtract the enhanced MAC-es header from
Remaining Granted Payload and Remaining Available Payload. With
this option, the RLC entity only has to take into account the
enhanced MAC-e header part for each RLC PDU it creates. If the
enhanced MAC entity does not subtract the enhanced MAC-es header
part, then the RLC may take this into account when generating RLC
PDUs.
[0036] Following each of steps 335 and 340, it is determined in
step 350 if RLC PDUs were provided from the requested RLC logical
channel. If no RLC PDUs were provided from the requested logical
channel, then procedure 300 returns to step 305 to be repeated for
the next logical channel. If bits were provided from the RLC
logical channel, then in step 355, it is determined if the sum of
the size of the RLC PDU(s) delivered plus a MAC-e header part is
greater than the requested number of bits. For example, if N RLC
PDUs were delivered, where N is greater than or equal to 1, then
the enhanced MAC-e header part to be added equals N times a number
of bits h2, and the sum is compared to the requested number of bits
which may be equal to MIN(Remaining Granted Payload, Remaining
Available Payload). If the number of delivered bits from the RLC
logical channel plus an enhanced MAC-e header part of N.times.h2
bits is less than the number of requested bits, then in step 370
the bits from the delivered RLC PDU(s) are added to the enhanced
MAC-e PDU up to a number of bits equal to MIN(Remaining Granted
Payload, Remaining Available Payload).
[0037] If the number of delivered bits from the RLC plus the
enhanced MAC-e header part is greater than the number of requested
bits, then in step 360, one or more complete RLC PDUs are added to
the enhanced MAC-e PDU according to the requested number of bits
and a last RLC PDU is then segmented and added to the enhanced
MAC-e PDU according to the remaining available and granted space.
More specifically, one or more complete RLC PDUs are added such
that the sum of the RLC PDUs plus an enhanced MAC-e header part per
RLC PDU is less than the number of requested bits. The remaining
available space in terms of bits for the segmented last RLC PDU is
determined according to the minimum of x1 and x2 where x1=Remaining
Granted Payload-(size of RLC PDUs added to the enhanced MAC-e+h2
per RLC PDU added-h2 for the segment to be added) and x2=Remaining
Available Payload-(size of RLC PDUs added to the enhanced MAC-e+h2
per RLC PDU added-h2 for the segment to be added). In step 365, the
remaining segment or bits are stored in the segmentation
buffer.
[0038] Following each of steps 365 and 370, the total number of
bits added to the enhanced MAC-e PDU, which includes bits from
associated headers, are subtracted from the Remaining Granted
Payload and Remaining Available Payload in step 375. In step 380,
the Remaining Available Payload is used up, or if no more data is
available in the logical channels in the current TTI, then
procedure 300 ends for that TTI. If the Remaining Available Payload
is not all used up and if data is still available in the logical
channels, then procedure 300 returns to step 305.
[0039] FIG. 4 shows a flow diagram of a procedure 400 for filling a
MAC-e PDU with data from logical channels as part of E-TFC
selection in accordance with another embodiment. According to
procedure 400, the MAC entity performs multiple requests to the RLC
entity. The MAC entity asks for an RLC PDU size based on the
selected E-TFC. If, after receiving the requested RLC PDU, there is
still space available in the enhanced MAC-e PDU, the MAC entity may
request additional RLC PDUs until the number of bits allowed to be
transmitted for that logical channel is reached or exceeded. The
Remaining Available Payload and Remaining Granted Payload have the
same definition as provided above. Additionally, the variable h1
refers to the additional number of header bits required for
including a first RLC PDU or segment thereof, and the variable h2
refers to the additional number of header bits required for
including subsequent RLC PDUs or segments thereof belonging to the
same logical channel. The variable B refers to the number of bits
currently available for a logical channel.
[0040] Referring to FIG. 4, in step 405, for a logical channel
allowed to transmit in the current TTI, a maximum number of bits B
currently available for the logical channel are determined
according to MIN(Remaining Available Payload, Remaining Granted
Payload). As mentioned above, the Remaining Available Payload may
take into account the quantization loss.
[0041] In step 410, if the segmentation buffer contains bits or a
segment to be transmitted, then the enhanced MAC-e PDU is filled
with as many bits as possible from the segmentation buffer while
leaving room for the header; if the segment is larger than B-h1,
then the segment is segmented to add it to the enhanced MAC-e PDU
and the remaining bits are stored in the segmentation buffer. In
step 415, the corresponding header is inserted in the enhanced
MAC-e PDU and the number of bits added to the enhanced MAC-e PDU
including header size h1 are subtracted from B.
[0042] In step 420, it is determined if B is greater than 0. If B
is not greater than 0, then in step 428 it is determined if there
is space available in the enhanced MAC-e PDU. If there is space in
the enhanced MAC-e PDU, then procedure 400 returns to step 405 and
is repeated for the next logical channel, if any, that is allowed
to transmit in the current TTI. If there is no more space in the
enhanced MAC-e PDU, then the procedure 400 ends.
[0043] If B is greater than 0, then in step 425 an RLC PDU is
requested from the RLC entity of size (B-h2) bits if data was
included from the segmentation buffer (in step 410), or of size
(B-h1) if data was not included from the segmentation buffer (in
step 410). In step 430, it is determined if the RLC entity
delivered an RLC PDU. If the RLC entity did not deliver an RLC PDU,
then procedure 400 returns to step 405 and is repeated for the next
logical channel, if any, that is allowed to transmit in the current
TTI.
[0044] If the RLC entity did deliver an RLC PDU, then in step 435
it is determined if the size of the delivered RLC PDU is less than
the requested RLC PDU size, in terms of number of bits. If the
delivered RLC PDU size is greater than the requested RLC PDU size,
then in step 450, the enhanced MAC-e PDU is filled with as many
bits as possible from the delivered RLC PDU while leaving room for
the header; if the delivered RLC PDU had to be segmented to fit
into the enhanced MAC-e PDU, then the remaining bits are stored in
the segmentation buffer. Subsequently, procedure 400 returns to
step 405 and is repeated for the next logical channel, if any, that
is allowed to transmit in the current TTI.
[0045] If the delivered RLC PDU size is less than the requested RLC
PDU size, then in step 440 the enhanced MAC-e PDU is filled with
the delivered RLC PDU and the corresponding header, and the size of
the RLC PDU and header are subtracted from B. Subsequently,
procedure 400 returns to step 420 in order to attempt to fill the
remaining space in the MAC-e PDU.
[0046] FIG. 5 shows a flow diagram of a procedure 500 for filling a
MAC-e PDU with data from logical channels as part of E-TFC
selection in accordance with another embodiment. According to
procedure 500, the MAC entity makes a single request to the RLC
entity to create one or more PDUs of a set size. The RLC takes
these inputs, and based on the amount of available data and the
maximum amount of data to be transmitted, sends N RLC PDUs of the
requested size. If an RLC PDU needs to be retransmitted, the RLC
sends the retransmitted PDU(s), and if space is still available,
also sends N new RLC PDUs of requested size. When choosing the
number of RLC PDUs to be sent to the enhanced MAC-e/es entity, the
RLC entity can send at a most one additional PDU, which exceeds the
maximum available size to be transmitted.
[0047] Referring to FIG. 5, in step 505, for a logical channel
allowed to transmit in the current TTI, a maximum number of bits B
currently available for the logical channel are determined
according to MIN(Remaining Available Payload, Remaining Granted
Payload). As mentioned above, the Remaining Available Payload may
take into account the quantization loss.
[0048] In step 510, if the segmentation buffer contains bits or a
segment to be transmitted, then the enhanced MAC-e PDU is filled
with as many bits as possible from the segmentation buffer while
leaving room for the header; if the segment is larger than B-h1,
then the segment is segmented to add it to the enhanced MAC-e PDU
and the remaining bits are stored in the segmentation buffer. In
step 515, the corresponding header is inserted in the enhanced
MAC-e PDU and the number of bits added to the enhanced MAC-e PDU
including header size h1 are subtracted from B.
[0049] In step 520, it is determined if B is greater than 0. If B
is not greater than 0, then in step 528 it is determined if there
is space available in the enhanced MAC-e PDU. If there is space in
the enhanced MAC-e PDU, then procedure 500 returns to step 505 and
is repeated for the next logical channel, if any, that is allowed
to transmit in the current TTI. If there is no more space in the
enhanced MAC-e PDU, then the procedure 500 ends.
[0050] If B is greater than 0, then in step 525 an RLC PDU is
requested from the RLC entity of size (B-h2) bits if data was
included from the segmentation buffer (in step 510), or of size
(B-h1) if data was not included from the segmentation buffer (in
step 510); if (B-h2) or (B-h1) is larger than the maximum allowed
RLC PDU size, PDUs of the maximum RLC PDU size are requested and
the RLC entity is provided with either a number of PDUs equal to
(B-h2 or h1)/(maximum RLC PDU size), or the PDU size and the
allowed number of bits to be transmitted. The enhanced MAC entity
may consider the header size or the RLC may take the header size
into account.
[0051] In step 530, it is determined if the RLC entity delivered an
RLC PDU. If the RLC entity did not deliver an RLC PDU, then
procedure 500 returns to step 505 and is repeated for the next
logical channel, if any, that is allowed to transmit in the current
TTI.
[0052] If the RLC entity did deliver an RLC PDU, then in step 535
it is determined if the size of the delivered RLC PDU(s) is less
than the available space in the enhanced MAC-e PDU. If the
delivered RLC PDU size is greater than the available space in the
enhanced MAC-e PDU, then in step 550, the MAC-e PDU is filled with
as many bits as possible from the delivered RLC PDU while leaving
room for the header; if the delivered RLC PDU had to be segmented
to fit into the MAC-e PDU, then the remaining bits are stored in
the segmentation buffer. Subsequently, procedure 500 returns to
step 505 and is repeated for the next logical channel, if any, that
is allowed to transmit in the current TTI.
[0053] If the delivered RLC PDU size is less than the available
space in the enhanced MAC-e PDU, then in step 540 the MAC-e PDU is
filled with the delivered RLC PDU and the corresponding header, and
the size of the RLC PDU and header are subtracted from B.
Subsequently, procedure 500 returns to step 510 in order to fill
the remaining space in the MAC-e PDU.
[0054] The RLC entity may also put a lower bound to the RLC PDU
size it can create, for example a minimum RLC size. The minimum RLC
PDU size can be configured by higher layers, or it can be a static
value or a calculated value for optimal transmission. For example,
if the number of bits requested by the MAC entity (or the number of
requested bits-number of bits of retransmitted RLC PDU(s)) is less
than the minimum RLC PDU size, then the RLC entity may do one or a
combination of the following: it may not send any data down to the
MAC entity, and it may create a larger RLC PDU with a size equal to
or greater than a minimum RLC PDU size, such that the MAC entity
will have to deal with a larger PDU.
[0055] In one embodiment, 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.
[0056] Alternatively, the UTRAN may determine the maximum RLC PDU
size and communicate the maximum RLC PDU size value to the WTRU
using L2 or L3 (RRC) signaling. For example, the UTRAN may
configure the WTRU 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.
[0057] According to another embodiment, a technique is provided for
maintaining a guaranteed bit rate (GBR) for non-scheduled data
flows with variable-length headers. Non-scheduled data flows are
data flows with a configured Guaranteed Bit Rate. With the
introduction of Layer 2 enhancements in the uplink (UL), the
enhanced MAC-e/es overhead became dependent on the RLC PDU size and
on the number of RLC PDUs in the enhanced MAC-es PDU. When the
network configures the grant for a non-scheduled data flows, it
configures it so that the power used to transmit this data is
enough to transmit the amount of required bits plus enhanced
MAC-e/es header bits. The proposed method guarantees that the right
amount of data can be transmitted within the configured grant,
taking into account that the header fields vary based on the number
of enhanced MAC-es SDUs. As described above, h1 refers to the
additional number of header bits required for including a first RLC
PDU or segment thereof, and h2 refers to the additional number of
header bits required for including subsequent RLC PDUs or segments
thereof belonging to the same logical channel. B refers to the
number of bits current available for a logical channel.
[0058] In order to guarantee a bit rate for the non-scheduled data
flows, any one of the following procedures may be used, alone or in
combination. In one procedure, the network may give a conservative
grant to the non-scheduled flow by taking into account the worst
case scenario for enhanced MAC-e/es header space. This may be done
by signaling or assuming a minimum RLC PDU size, for example, 300
bits, such that the RLC entity does not create RLC PDUs smaller
than the minimum size, although MAC entity is allowed to segment
those RLC PDUs. This establishes a worst-case overhead for the
radio network controller (RNC), which is then used by the RNC to
determine the non-scheduled grant. For example, if the intended GBR
equals X bits/TTI, the network may allocate a non-scheduled grant
of (X+h2+((X/min RLC PDU size)-1)*(h1) bits, accounting for the
possibility of segmentation. In an alternate procedure, the network
may give a conservative grant as described above, but based on an
average RLC PDU size. In the case where the RLC PDUs are smaller
than the average, the non-scheduled flow can take some of the
scheduled flow's power to ensure that the required number of bits
is transmitted. In another procedure, the network can configure a
more flexible non-scheduled grant. This may be done by giving the
WTRU an absolute value and a variance value, for example a +/-
value, the WTRU is allowed to use).
[0059] FIG. 6 shows a flow diagram of a simplified procedure 600
for filling an enhanced MAC-e PDU with data from logical channels
as part of E-TFC selection in accordance with another embodiment.
In step 605, if there is a segment in the segmentation buffer, the
segment is added to the enhanced MAC-e PDU, where the segment may
be re-segmented to fit into the MAC-e PDU. In step 610, if there is
space in the enhanced MAC-e PDU, a maximum number of bits allowed
to be transmitted is requested from the RLC entity. In step 615,
the received RLC PDU(s) is added to the MAC-e PDU to fill the
available space in the MAC-e PDU, and a final RLC PDU may be
segmented if needed in order to fit in the MAC-e PDU. Additionally,
any of the steps in any of the procedures described above may be
used in combination with procedure 600 to create an enhanced MAC-e
PDU.
[0060] The procedure 300 of FIGS. 3A and 3B, the procedure 400 of
FIG. 4, the procedure 500 of FIG. 5 and/or the procedure 600 of
FIG. 6 as part of E-TFC selection may be performed by the E-TFC
selection entity 212 of FIG. 2, where segmentation of RLC PDUs is
performed by the segmentation entity 214 and segments may be stored
in the segmentation buffer 216. Requests for bits from MAC-c, MAC-d
or RLC entities are made by enhanced MAC-e/es entity 210.
[0061] 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).
[0062] 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.
[0063] 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.
* * * * *