U.S. patent application number 15/059152 was filed with the patent office on 2016-06-23 for method and apparatus for versatile mac multiplexing in evolved hspa.
This patent application is currently assigned to InterDigital Technology Corporation. The applicant listed for this patent is InterDigital Technology Corporation. Invention is credited to Sudheer A. Grandhi, Paul Marinier, Diana Pani, Stephen E. Terry.
Application Number | 20160183124 15/059152 |
Document ID | / |
Family ID | 39645652 |
Filed Date | 2016-06-23 |
United States Patent
Application |
20160183124 |
Kind Code |
A1 |
Marinier; Paul ; et
al. |
June 23, 2016 |
METHOD AND APPARATUS FOR VERSATILE MAC MULTIPLEXING IN EVOLVED
HSPA
Abstract
Methods and apparatus for versatile medium access control (MAC)
multiplexing in evolved HSPA are disclosed. More particularly,
methods for downlink optimization of the enhanced high speed MAC
(MAC-ehs) entity and uplink optimization of the MAC-i/is entity are
disclosed. Apparatuses for using the optimized downlink and uplink
MAC entities are also disclosed.
Inventors: |
Marinier; Paul; (Brossard,
CA) ; Pani; Diana; (Montreal, CA) ; Terry;
Stephen E.; (Northport, NY) ; Grandhi; Sudheer
A.; (Pleasanton, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InterDigital Technology Corporation |
Wilmington |
DE |
US |
|
|
Assignee: |
InterDigital Technology
Corporation
Wilmington
DE
|
Family ID: |
39645652 |
Appl. No.: |
15/059152 |
Filed: |
March 2, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14835302 |
Aug 25, 2015 |
9313690 |
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15059152 |
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13875730 |
May 2, 2013 |
9160675 |
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14835302 |
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12024900 |
Feb 1, 2008 |
8503423 |
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13875730 |
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60887957 |
Feb 2, 2007 |
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60893298 |
Mar 6, 2007 |
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60912063 |
Apr 16, 2007 |
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61019129 |
Jan 4, 2008 |
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Current U.S.
Class: |
370/229 |
Current CPC
Class: |
H04W 80/02 20130101;
H04L 49/9094 20130101; H04L 47/34 20130101; H04W 28/06 20130101;
H04L 49/90 20130101 |
International
Class: |
H04W 28/06 20060101
H04W028/06; H04L 12/861 20060101 H04L012/861; H04L 12/801 20060101
H04L012/801 |
Claims
1. A method for creating a medium access control (MAC) enhanced
high speed (MAC-ehs) header for a MAC protocol data unit (PDU), the
method comprising: creating the MAC-ehs header for the MAC PDU, the
MAC-ehs header comprising a segmentation indication (SI) field for
a reordering PDU, the SI field indicating: whether a first
reordering SDU in the reordering PDU is a last segment of a MAC-ehs
SDU, or whether a last reordering SDU in the reordering PDU is a
first segment of a MAC-ehs SDU.
2. The method of claim 1, wherein the SI field indicates that the
first reordering SDU of the reordering PDU is the last segment of
the MAC-ehs SDU, and, if there are more than one reordering SDUs in
the reordering PDU, the last reordering SDU of the reordering PDU
is a complete MAC-ehs SDU.
3. The method of claim 1, wherein the SI field indicates that the
last reordering SDU is the first segment of the MAC-ehs SDU, and,
if there are more than one reordering SDUs in the reordering PDU,
the first reordering SDU of the reordering PDU is a complete
MAC-ehs SDU.
4. The method of claim 1, wherein the SI field indicates that there
is one reordering SDU in the reordering PDU that is a middle
segment of a MAC-ehs SDU.
5. The method of claim 1, wherein the SI field indicates that, if
there are more than one reordering SDUs in the reordering PDU, the
first reordering SDU of the reordering PDU is the last segment of
the MAC-ehs SDU and the last reordering SDU of the reordering PDU
is the first segment of the MAC-ehs SDU.
6. The method of claim 1, wherein the reordering PDU includes one
or more segments of one or more MAC-ehs SDUs.
7. A base station for creating a medium access control (MAC)
enhanced high speed (MAC-ehs) header for a MAC protocol data unit
(PDU), the base station comprising: a processor configured to
create the MAC-ehs header for the MAC PDU, the MAC-ehs header
comprising a segmentation indication (SI) field for a reordering
PDU, the SI field indicating: whether a first reordering SDU in the
reordering PDU is a last segment of a MAC-ehs SDU, or whether a
last reordering SDU in the reordering PDU is a first segment of a
MAC-ehs SDU.
8. The base station of claim 7, wherein the SI field indicates that
the first reordering SDU of the reordering PDU is the last segment
of the MAC-ehs SDU, and, if there are more than one reordering SDUs
in the reordering PDU, the last reordering SDU of the reordering
PDU is a complete MAC-ehs SDU.
9. The base station of claim 7, wherein the SI field indicates that
the last reordering SDU is the first segment of the MAC-ehs SDU,
and, if there are more than one reordering SDUs in the reordering
PDU, the first reordering SDU of the reordering PDU is a complete
MAC-ehs SDU.
10. The base station of claim 7, wherein the SI field indicates
that there is one reordering SDU in the reordering PDU that is a
middle segment of a MAC-ehs SDU.
11. The base station of claim 7, wherein the SI field indicates
that, if there are more than one reordering SDUs in the reordering
PDU, the first reordering SDU of the reordering PDU is the last
segment of the MAC-ehs SDU and the last reordering SDU of the
reordering PDU is the first segment of the MAC-ehs SDU.
12. The base station of claim 7, wherein the reordering PDU
includes one or more segments of one or more MAC-ehs SDUs.
13. A method for interpreting a segmentation indication (SI) field
in a header of a medium access control (MAC) protocol data unit
(PDU), the method comprising: receiving a value of the SI field in
the MAC header, the SI field corresponding to a reordering PDU; and
interpreting, based on the value of the SI field, whether a first
reordering SDU of the reordering PDU is a last segment of a MAC-ehs
SDU or whether a last reordering SDU of the reordering PDU is a
first segment of a MAC-ehs SDU.
14. The method of claim 13, further comprising interpreting, based
on the SI field, that the first reordering SDU of the reordering
PDU is the last segment of the MAC-ehs SDU, and, if there are more
than one reordering SDUs in the reordering PDU, the last reordering
SDU of the reordering PDU is a complete MAC-ehs SDU.
15. The method of claim 13, further comprising interpreting, based
on the SI field, that the last reordering SDU is the first segment
of the MAC-ehs SDU, and, if there are more than one reordering SDUs
in the reordering PDU, the first reordering SDU of the reordering
PDU is a complete MAC-ehs SDU.
16. The method of claim 13, further comprising interpreting, based
on the SI field, that there is one reordering SDU in the reordering
PDU that is a middle segment of a MAC-ehs SDU.
17. The method of claim 13, further comprising interpreting, based
on the SI field, that, if there are more than one reordering SDUs
in the reordering PDU, the first reordering SDU of the reordering
PDU is the last segment of the MAC-ehs SDU and the last reordering
SDU of the reordering PDU is the first segment of the MAC-ehs
SDU.
18. A wireless transmit/receive unit (WTRU) for interpreting a
segmentation indication (SI) field in a header of a medium access
control (MAC) protocol data unit (PDU), the WTRU comprising: a
processor configured to: receive a value of the SI field in the MAC
header, the SI field corresponding to a reordering PDU; and
interpret, based on the value of the SI field, whether a first
reordering SDU of the reordering PDU is a last segment of a MAC-ehs
SDU or whether a last reordering SDU of the reordering PDU is a
first segment of a MAC-ehs SDU.
19. The WTRU of claim 18, wherein the processor is further
configured to interpret, based on the SI field, that the first
reordering SDU of the reordering PDU is the last segment of the
MAC-ehs SDU, and, if there are more than one reordering SDUs in the
reordering PDU, that the last reordering SDU of the reordering PDU
is a complete MAC-ehs SDU.
20. The WTRU of claim 18, wherein the processor is further
configured to interpret, based on the SI field, that the last
reordering SDU of the reordering PDU is the first segment of the
MAC-ehs SDU, and, if there are more than one reordering SDUs in the
reordering PDU, the first reordering SDU of the reordering PDU is a
complete MAC-ehs SDU.
21. The WTRU of claim 18, wherein the processor is further
configured to interpret, based on the SI field, that there is one
reordering SDU in the reordering PDU that is a middle segment of a
MAC-ehs SDU.
22. The WTRU of claim 18, wherein the processor is further
configured to interpret, based on the SI field, that, if there are
more than one reordering SDUs in the reordering PDU, the first
reordering SDU of the reordering PDU is the last segment of the
MAC-ehs SDU and the last reordering SDU of the reordering PDU is
the first segment of the MAC-ehs SDU.
23. A method for processing a segmentation indication (SI) field in
a header of a medium access control (MAC) protocol data unit (PDU),
the method comprising: receiving a value of the SI field in the MAC
header, the SI field corresponding to a reordering PDU; and
delivering one or more MAC PDUs to a demultiplexing entity based on
the SI field, wherein, when the SI field has a value indicating
that a first reordering SDU of the reordering PDU is a last segment
of a MAC-ehs SDU, the one or more MAC PDUs are delivered based on
whether a received segment of a MAC-ehs SDU and a stored segment of
a MAC-ehs SDU are consecutive, or wherein, when the SI field has a
value indicating that a last reordering SDU of the reordering PDU
is a first segment of a MAC-ehs SDU, the one or more MAC PDUs
correspond to each reordering SDU in the reordering PDU except a
last reordering SDU.
24. The method of claim 23, further comprising: combining the
received segment of the MAC-ehs SDU and the stored segment of the
MAC-ehs SDU; and delivering the combined segments to the
demultiplexing entity.
25. The method of claim 23, further comprising discarding the
received segment of the MAC-ehs SDU and the stored segment of the
MAC-ehs SDU when the received segment of the MAC-ehs SDU and the
stored segment of the MAC-ehs SDU are not consecutive.
26. The method of claim 23, wherein when the received segment of
the MAC-ehs SDU and the stored segment of the MAC-ehs SDU are not
consecutive, the one or more MAC PDUs include a MAC PDU received
subsequent to the received segment of the MAC-ehs SDU and the
stored segment of the MAC-ehs SDU.
27. The method of claim 23, further comprising: discarding any
stored MAC-ehs PDUs; and storing the last reordering SDU.
28. The method of claim 23, wherein, when the SI field has a value
of indicating that there is one reordering SDU in the reordering
PDU that is a middle segment of a MAC-ehs SDU, the one or more MAC
PDUs are delivered based on whether a received segment of a MAC-ehs
SDU and a stored segment of a MAC-ehs SDU are consecutive.
29. A wireless transmit/receive unit (WTRU) for processing a
segmentation indication (SI) field in a header of a medium access
control (MAC) protocol data unit (PDU), the WTRU comprising: a
processor configured to: receive a value of the SI field in the MAC
header, the SI field corresponding to a reordering PDU; and deliver
one or more MAC PDUs to a demultiplexing entity based on the SI
field, wherein, when the SI field has a value indicating that a
first reordering SDU of the reordering PDU is a last segment of a
MAC-ehs SDU, the one or more MAC PDUs are delivered based on
whether a received segment of a MAC-ehs SDU and a stored segment of
a MAC-ehs SDU are consecutive, or wherein, when the SI field has a
value of indicating that a last reordering SDU of the reordering
PDU is a first segment of a MAC-ehs SDU, the one or more MAC PDUs
correspond to each reordering SDU in the reordering PDU except a
last reordering SDU.
30. The WTRU of claim 29, wherein the processor is further
configured to: combine the received segment of the MAC-ehs SDU and
the stored segment of the MAC-ehs SDU; and deliver the combined
segments to the demultiplexing entity.
31. The WTRU of claim 29, wherein the processor is further
configured to discard the received segment of the MAC-ehs SDU and
the stored segment of the MAC-ehs SDU when the received segment of
the MAC-ehs SDU and the stored segment of the MAC-ehs SDU are not
consecutive.
32. The WTRU of claim 29, wherein when the received MAC-ehs SDU and
the stored MAC-ehs SDU are not consecutive, the MAC PDUs include
MAC PDUs received subsequent to the received segment of the MAC-ehs
SDU and the stored segment of the MAC-ehs SDU.
33. The WTRU of claim 29, wherein the processor is further
configured to: discard any previously stored MAC-ehs PDUs; and
store the last reordering SDU.
34. The WTRU of claim 29, wherein, when the SI field has a value of
indicating that there is one reordering SDU in the reordering PDU
that is a middle segment of a MAC-ehs SDU, the WTRU is configured
to deliver the one or more MAC PDUs based on whether a received
segment of a MAC-ehs SDU and a stored segment of a MAC-ehs SDU are
consecutive.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 14/835,302, filed Aug. 25, 2015, which is a
continuation of U.S. patent application Ser. No. 13/875,730, filed
May 2, 2013, now issued as U.S. Pat. No. 9,160,675 on Oct. 13,
2015, which is a continuation of U.S. patent application Ser. No.
12/024,900, filed Feb. 1, 2008, now issued as U.S. Pat. No.
8,503,423 on Aug. 6, 2013, which claims benefit of U.S. Provisional
Application Nos. 60/887,957, filed Feb. 2, 2007, 60/893,298, filed
Mar. 6, 2007, 60/912,063, filed Apr. 16, 2007, and 61/019,129,
filed Jan. 4, 2008, which are incorporated by reference as if fully
set forth herein.
BACKGROUND
[0002] Communications standards are developed in order to provide
global connectivity for wireless systems and to achieve performance
goals in terms of, for example, throughput, latency and coverage.
One current standard in widespread use, called high speed packed
access (HSPA), was developed as part of Third Generation (3G) Radio
Systems, and is maintained by the Third Generation Partnership
Project (3GPP).
[0003] High-Speed Packet Access (HSP) is a collection of mobile
telephone protocols that extend and improve the performance of
existing Universal Mobile Telecommunications System (UMTS)
protocols. High Speed Downlink Packet Access (HSDPA) and High Speed
Uplink Packet Access (HSUPA) provide increased performance by using
improved modulation schemes and by refining the protocols by which
handsets and base stations communicate.
[0004] HSPA provides improved theoretical downlink (DL) performance
of up to 14.4 Mbit/s and improved theoretical uplink (UL)
performance of up to 5.76 Mbit/s. Existing deployments provide up
to 7.2 Mbit/s in the DL and up to 384 kbit/s in the UL. Evolved
HSPA is defined in 3GPP Release 7. It introduces simpler
architecture for mobile network by bypassing most of the legacy
equipment and enhancing radio due rates.
[0005] Above the physical layer in a 3GPP system, a Medium Access
Control (MAC) layer may be divided into several entities. A new MAC
entity, MAC enhanced high speed (MAC-ehs), has been introduced and
optimized for HSPA in the DL. The MAC-ehs entity can be used
alternatively to MAC high speed (MAC-hs). In the UL a new MAC
entity, improved MAC (MAC-ii) has been introduced and optimized for
HSPA. The MAC-i/is entity can be used alternatively to MAC-e/es.
The MAC-ehs and/or MAC-i/is entity is configured by higher layers
which are configured to handle the data transmitted on the High
Speed Downlink Shared Channel (HS-DSCH) and/or Enhanced Uplink
Channel (E-DCH) and manage the physical resources allocated to
HS-DSCH.
[0006] The MAC-ehs entity allows the support of flexible radio link
control (RLC) protocol data unit (PDU) sizes as well as MAC
segmentation and reassembly. Unlike MAC-hs for HSDPA, MAC-ehs
allows the multiplexing of data from several priority queues within
one transmission time interval (TTI) of 2 ms.
[0007] The scheduling/priority handling function is responsible for
the scheduling decisions. For each TTI of 2 ms, it is decided
whether single or dual stream transmission is used. New
transmissions or retransmissions are sent according to the
acknowledgement/negative acknowledgement (ACK/NACK) UL feedback,
and new transmissions can be initiated at any time. While in the
CELL_FACH, CELL_PCH, and URA_PCH states, the MAC-ehs can
additionally perform retransmissions on HS-DSCH without relying on
uplink signaling.
[0008] Reordering on the receiver side is based on priority queues.
Transmission sequence numbers (TSN) are assigned within each
reordering queue to enable reordering. On the receiver side, the
MAC-ehs SDU, or segment thereof; is assigned to the correct
priority queue based on the logical channel identifier.
[0009] The MAC-ehs SDUs can be segmented on the transmitter side
and are reassembled on the receiver side. At the MAC layer, a set
of logical channels is mapped to a transport channel. Two types of
transport channels include, a "common" transport channel (MAC-c)
which can be shared by multiple WTRUs, and a "dedicated" transport
channel (MAC-d) which is allocated to a single WTRU. A MAC-ehs SDU
is either a MAC-c PDU or MAC-d PDU. The MAC-ehs SDUs included in a
MAC-ehs PDU can have different sizes and different priorities and
can belong to different MAC-d or MAC-c flows.
[0010] The typical baseline of the MAC-ehs header results in fairly
low overhead when the MAC-ehs multiplexes logical channels that are
used by Release 7 RLC acknowledge mode (AM) instances configured
with a flexible RLC PDU size. This is due to the size of a MAC SDU
being significantly larger than the total size of the different
fields of the header.
[0011] However, there are situations where the typical baseline
would result in an undesirable level of overhead. For example, a
logical channel is used by an RLC AM instance configured with a
fixed RLC PDU size, or to a Release 6 RLC AM instance. The latter
instance may result from the possibility of enabling handover from
a Release 6 base station to a 3GPP Release 7 base station without
resetting the RLC and keeping the RLC entity configured to operate
with fixed RLC PDUs. In another example, the MAC-ehs PDU size
possible with current channel conditions is small and contains a
few (e.g., 2) segments of SDUs. In this example, the header may
constitute a significant overhead.
[0012] Typical signaling requirements to support MAC-ehs
functionalities are inefficient. It would be desirable to reduce
the amount of signaling required to support MAC-ehs PDU
functionalities. One possibility to reduce signaling would be to
perform multiplexing/de-multiplexing of SDUs of different sizes,
from different logical channels and priority queues in a single
MAC-ehs PDU at the base station. Another possibility would be to
perform multiplexing/de-multiplexing of SDUs of different sizes and
belonging to different logical channels. Finally,
concatenation/disassembly and segmentation/reassembly of MAC-ehs
SDUs would be desirable.
[0013] Table 1 shows encoding of the segmentation indication (SI)
field, when the segmentation indication is defined per priority
queue. The meaning of the field may cause confusion at the WTRU
side when padding is present at the end of the MAC-ehs header after
the last segment of an SDU. In this case, the segmentation
indication as per the indicated encoding would need to be "11."
However, the WTRU could interpret this as meaning that the SDU is
not complete and insert it in a reassembly buffer. It would be
desirable to modify the encoding of this field to avoid this
confusion.
TABLE-US-00001 TABLE 1 SI Field Segmentation indication 00 The
first MAC-hs SDU of the addressed set of MAC-hs SDUs is a complete
MAC-d PDU. The last MAC-hs SDU of the addressed set of MAC-hs SDUs
is a complete MAC-d PDU. 01 The first MAC-hs SDU of the addressed
set of MAC-hs SDUs is a segment of a MAC-d PDU. The last MAC-hs SDU
of the addressed set of MAC-hs SDUs is a complete MAC-d PDU. 10 The
first MAC-hs SDU of the addressed set of MAC-hs SDUs is a complete
MAC-d PDU. The last MAC-hs SDU of the addressed set of MAC-hs SDUs
is a segment of a MAC-d PDU. 11 The first MAC-hs SDU of the
addressed set of MAC-hs SDUs is a segment of a MAC-d PDU. The last
MAC-hs SDU of the addressed set of MAC-hs SDUs is a segment of a
MAC-d PDU.
SUMMARY
[0014] Methods and apparatuses for versatile medium access control
(MAC) multiplexing in evolved HSPA are disclosed. More
particularly, methods for downlink optimization of the enhanced
high speed MAC (MAC-ehs) entity and uplink optimization of the
MAC-i/is entity are disclosed. Apparatuses for using the optimized
downlink and uplink MAC entities are also disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] A more detailed understanding may be had from the following
description, given by way of example and to be understood in
conjunction with the accompanying drawings wherein:
[0016] FIG. 1 is a block diagram of a wireless communication system
configured for versatile MAC multiplexing in evolved HSPA;
[0017] FIG. 2 is a payload header used in multiplexing SDUs from
different logical channels and priority queues;
[0018] FIG. 3a is the general structure of an SDU description
super-field (SDSF) field arranged to efficiently signal how SDUs
are concatenated/segmented, their sizes, and the logical channels
to which they correspond;
[0019] FIG. 3b is a payload header format of a MAC-ehs PDU that
contains k reordering PDUs used in multiplexing reordering PDUs
from different logical channels and priority queues;
[0020] FIG. 4 is a flow diagram of the operations to process the
MAC-ehs PDUs and reconstruct the MAC-ehs SDUs;
[0021] FIG. 5 is a flow diagram of data processing functionality
within each disassembly/reassembly/demultiplexing unit;
[0022] FIG. 6 is the parts of the header describing SDU(s)
belonging to the concerned logical channels to allow efficient
multiplexing of different types of logical channels in the same
MAC-ehs PDU;
[0023] FIG. 7 is an alternate configuration for the header
describing SDU(s) belonging to the concerned logical channels to
allow efficient multiplexing of different types of logical channels
in the same MAC-ehs PDU;
[0024] FIG. 8 is an alternate configuration for the header
describing SDU(s) belonging to the concerned logical channels to
allow efficient multiplexing of different types of logical channels
in the same MAC-hs PDU;
[0025] FIG. 9 is an alternate configuration for the header
describing SDU(s) belonging to the concerned logical channels to
allow efficient multiplexing of different types of logical channels
in the same MAC-ehs PDU;
[0026] FIG. 10 is a flow diagram of a modified method for
interpretation of the SI field where the reordering PDU contains
only one reordering SDU;
[0027] FIG. 11 is how a 2-bit SI field can be used as one possible
encoding for minimizing overhead;
[0028] FIG. 12 is an alternative method of formulating the encoding
where the SI field may be predetermined;
[0029] FIG. 13 is a flow diagram of how the reassembly unit
processes the SI field associated with a reordering PDU;
[0030] FIG. 14 is a flow diagram of how a reassembly unit may
perform a combining function or a discarding function;
[0031] FIG. 15 is a flow diagram of how payload units should be
processed if there are multiple reordering SDUs in the reordering
PDU;
[0032] FIG. 16 is a flow diagram of the combined reassembly process
shown in FIGS. 14 and 15; and
[0033] FIG. 17 is a flow diagram of how the reassembly unit
processes the SI field associated with a reordering PDU.
DETAILED DESCRIPTION
[0034] 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.
[0035] Embodiments resulting in an efficient MAC-ehs header (or
MAC-ids in the uplink) in the above-mentioned situations are
disclosed. The embodiments improve the header structure to minimize
the relative overhead while allowing multiplexing of logical
channels of different types. The embodiments also eliminate the
issue where a potentially ambiguous interpretation of the header
could result when a unique segment of a SDU is present in the
payload. The following definition is used throughout: "MAC-ehs
payload unit" ("MAC-is payload unit") or "payload unit" are
synonymous with a MAC-ehs SDU or a MAC-ehs SDU ("MAC-is SDU")
segment that is inserted in the payload of a MAC-ehs PDU ("MAC-is
SDU"). It is also synonymous with the term "reordering SDU".
Although the embodiments describe downlink optimization of the
MAC-ehs entity, the concepts are also applicable to the uplink (UL)
by replacing the MAC-ehs with the MAC-i/is.
[0036] FIG. 1 is a block diagram of a wireless communication system
100 configured for versatile MAC multiplexing in evolved HSPA. The
system includes a base station 105 and a wireless transmit receive
unit (WTRU) 110. The base station 105 and the WTRU 110 communicate
via a wireless communications link.
[0037] As shown in FIG. 1, the WTRU 110 includes a transmitter 120,
a receiver 130, and a processor 140. The processor 140 is attached
to a buffer 150 and a memory 160. The processor 140 is configured
to process payload units using at least one technique described
below.
[0038] Also shown in FIG. 1, is the base station 105 which includes
a transmitter 165, a receiver 170, and a processor 180. The
processor 180 is attached to a buffer 190 and a memory 195. The
processor 180 is configured to process payload units using at least
one technique described below.
[0039] FIG. 2 is a payload header 200 used in multiplexing SDUs
from different logical channels and priority queues. In a first
embodiment, the multiplexing of SDUs from multiple priority queues
into a single MAC-ehs PDU is disclosed. In addition, merging SDUs
from multiple logical channels into a single priority queue is
included.
[0040] A MAC-ehs PDU is built by concatenating and/or segmenting
one or more SDUs from one or more priority queues. A header is
attached to the payload in a structure as set forth in FIG. 2. The
header 280 includes a plurality of k queue sections 205, each k
queue section 205 including a transmission sequence number (TSN)
240, an SDU description super-field (SDSF) 250, and a "finish" flag
(F) 260. Each k queue section 205 corresponds to a priority queue
from which SDU(s) (or segments thereof) are taken, where k is the
number of priority queues from which SDUs are multiplexed in this
MAC-ehs PDU. The header 280 can also include an optional version
flag 210 and/or an optional queue ID field 280.
[0041] The optional version flag 210 indicates which version of the
protocol is used to ensure backward compatibility. As a prior
version of the MAC-ehs exists, this field should have two bits. The
version flag 210 may be used when the radio bearer is mapped to
support different MAC-ehs header formats. Each radio bearer is
configured to use a particular format. Alternatively, the MAC-ehs
format may be identified either explicitly or implicitly by
signaling on the High Speed Shared Control Channel (HS-SCCH). Radio
bearer multiplexing into a MAC-ehs PDU may be restricted by the
MAC-ehs format configured for the radio bearer.
[0042] As shown in FIG. 2, each header 280 can include an optional
queue ID field 230 which identifies to which reordering queue the
corresponding SDUs in the payload belong. The reordering queues may
or may not directly map to priority queues. The header 280 also
includes at least one transmission sequence number (TSN) field 240
which identifies the sequence number of the data for this queue ID.
Another feature included in the header 280 is at least one SDU
description super-field (SDSF) 250 which indicates how to
disassemble and/or reassemble SDUs and which logical channel(s)
they belong to. Details and options for this super-field are
described hereinafter. The header 280 could also include at least
one optional "finish" flag 260 indicating whether this header
section is the last section of the header or another sub-header
follows.
[0043] The MAC-ehs header 280 is followed by the MAC-ehs payload
290 which includes a series of MAC-ehs SDUs or segments of MAC-ehs
SDUs 295 and optional padding bits 270. The padding bits 270 can be
added to the payload 290 as required, to maintain octet alignment
at the MAC-ehs PDU level. Alignment with allowed Transport Block
(TB) sizes is mapped to the HS-DSCH transport channel (TrCH).
[0044] As shown in FIG. 3a, the SDU description super-field 250 is
arranged as to efficiently signal how SDUs from one priority queue
are concatenated/segmented, their sizes, and the logical channels
to which they correspond.
[0045] Without loss of performance, SDUs can be segmented in a
sequential manner within a priority queue. This means transmission
of an SDU, or segment thereof is restricted unless the last SDU or
segment of the previous SDU has been transmitted (or is being
transmitted in the same MAC-ehs PDU). With this constraint, at most
two segments of (different) SDUs are present for a particular
reordering queue in a MAC-ehs PDU, along with an unrestricted
number of full (non-segmented SDUs) in between.
[0046] FIG. 3b is a payload header format of a MAC-ehs PDU that
contains k reordering PDUs used in multiplexing reordering PDUs
from different logical channels and priority queues. The position
of the start of the payload 290 within the MAC-ehs PDU 395 for each
reordering queue is assumed to be identifiable. For the data
corresponding to the first reordering queue listed in the header
280, the start of the payload 290 immediately follows the header.
This is also possible for the data corresponding to the subsequent
reordering queues, provided that the SDSF field 250, shown in FIG.
3a, of each priority queue, with the exception of the last priority
queue, is configured to determine the total size of the
corresponding payload. The structure in FIG. 3a satisfies this
requirement.
[0047] As shown in FIG. 3a, the general structure of the SDSF field
250, includes the following elements. A "full/segment start" (FSS)
flag 320 indicates whether the data at the start position of the
payload for this reordering queue corresponds to a segment of an
SDU or a full SDU. A "full/segment end" (FSE) flag 360 follows the
FSS flag indicating whether the data at the end position of the
payload for this priority queue corresponds to a segment of a SDU
or a full SDU. The combination of the FS and the FSE is equivalent
to a segmentation indication (SI) field 397 shown in FIG. 3b. For
each SDU or SDU segment present in the payload 290, a logical
channel indicator (LCID) field 330 is included which indicates the
logical channel to which the SDU (or segment thereof) belongs, a
length indicator (LI) field 340 indicating the length of the SDU
(or segment thereof); (this field will be described in more detail
in a subsequent embodiment); and an "SDU end" flag 350 indicating
whether there is at least another SDU (or segment thereof)
following this SDU or if this is the last SDU (or segment thereof)
for this reordering queue; this field can have one bit.
[0048] It should be noted that both FSS 320 and FSE 360 flags
should be set even if there is only one SDU (or segment thereof).
It should also be noted that the FSS 320 and FSE 360 may be
identified as a single field of two bits, which could be called,
for instance, an SI. In this case, a one-to-one mapping may be
defined between each possible combination of values of the flags
FSS 320 and FSE and each possible combination of the two bits of
the SI field. For instance: [0049] FSS=Segment and FSE=Segment may
be mapped to SI=11 [0050] FSS=Full and FSE=Segment may be mapped to
SI=10 [0051] FSS=Segment and FSE=Full may be mapped to SI=01 [0052]
FSS=Full and FSE=Full may be mapped to SI=00 Conversely, with the
above mapping, the values of FSS and FSE may be retrieved as
follows from the SI field. [0053] FSS=Segment corresponds to the
first payload unit being a segment. [0054] If there is only one
payload unit and the segment is a middle segment it corresponds to
SI=11 (i.e. FSE is also set to Full). [0055] If the segment is a
last segment of a MAC-ehs SDU it corresponds to SI=01 when there is
a single payload unit or if the last payload unit is a complete
MAC-ehs SDU (i.e. FSE is set to Full) or to SI=11 when the last
payload unit is a segment (i.e. FSE is set to segment). [0056]
FSS=Full corresponds to SI=10 when there is a single payload unit
or when the last payload unit is a first segment of a MAC-ehs SDU
(i.e. FSE is set to Full) or SI=00 when only complete MAC-ehs SDUs
are present (i.e. FSE is also set to Full) [0057] FSE=Segment
corresponds to SI=11 or SI=10 depending on FSE as described above
[0058] FSE=Full corresponds to SI=01 or SI=00 depending on FSE as
described above. Also shown in FIG. 3a, the LCID 330 and LI 340
fields may together be identified as a single Data Description
Indicator (DDI) field similar to the one used in enhanced dedicated
channel (E-DCH) encoding for the uplink. However, the encoding
principles may be different as will be described below.
[0059] Several options are possible for the encoding of the LCID
field 330. One option is that the encoding may follow the same
identification scheme for the target channel type field (TCTF) and
control traffic numbering (C/T mux) in case of dedicated control
channel/dedicated traffic channel (DCCH/DTCH). In the MAO-c layer,
the TCTF fields and the C/T mux fields together identify a logical
channel. The TCTF identifies the target channel type while the C/T
mux identifies an index. In this option, the same type of encoding
as in MAC-c could be possible. In this case, the mapping between
TCTF and type of logical channel (e.g., common control channel
(CCCH), paging control channel (PCCH), dedicated control channel
(DCCH), etc.) may be specified in the same way as in known
embodiments. In this case, the number of bits occupied by the LCID
field are variable. Alternatively, the TCTF and C/T may be jointly
coded into a common parameter. The channel type may be configured
as C/T or unique values for the LCID may be specified.
[0060] Optionally, assuming that the maximum possible number of
logical channels (of all types) that the receiver may be utilizing
at a given time is NLmax, and NLmax can be represented by the
number of bits for these logical channels (NLMb bits), the LCID
field includes NLMb bits and contains a logical channel identifier.
For example, the network can configure up to 16 logical channels
(i.e. NLmax=16). Therefore, to be able to identify 16 logical
channels, 4 bits (i.e. NLMb=4) would be required. The mapping
between this logical channel identifier and the logical channel it
corresponds to is known from prior radio resource control/Node B
application part (RRC/NBAP) signaling and/or specified
(pre-determined) in advance. Some values could be reserved to types
of logical channels of which a single instance is possible. For
instance, there can be only one CCCH and a specific value may be
pre-determined for this channel.
[0061] Optionally, there could be a maximum possible number of
logical channels that can be multiplexed in a given priority queue
(NLQmax) which is smaller than the overall maximum possible number
of logical channels that the receiver can utilize as a whole. If
NLQmax can be represented by the number of bits that would be
required to identify NLQmax (NLMQb bits), the LCID field includes
NLMQb bits. In that case, the mapping between each possible set of
values for the NLMQb bits and the logical channel type and/or index
is specific to each priority queue and is known from prior RRC/NBAP
signaling (which specifies a potentially different mapping for each
defined priority queue). This option does not preclude the use of
pre-determined values for certain types of logical channels as set
forth above.
[0062] There are several options for configuring the MAC-ehs header
as will be described in detail hereinafter. As shown in FIG. 3a,
the SDSF field 250 may be defined to support the use of a "number"
(N) field 380 to minimize the overhead when multiple SDUs belong to
the same logical channel and/or have the same length follow each
other.
[0063] The N field 380 could always be present and precede (or
follow) the LCID 330 and LI 1340 fields for every group of N
consecutive SDUs that have the same length and belong to the same
logical channel.
[0064] The N field 380 could always be present and precede (or
follow) the LCID field 330 for every group of N consecutive SDUs
that belong to the same logical channel; however, each SDU would
have its own LI field 340.
[0065] The N field 380 could only be present for a group of N
consecutive SDUs (with same length and logical channel) if N is
larger than 1. A "multiple SDUs" (MS) flag 390 could indicate
whether the N field 380 is present or not. This reduces the risk of
excessive overhead due to the presence of the N field 380 when the
SDUs of the payload are all of different length or belong to
different logical channels.
[0066] The N field 380 could only be present for a group of N
consecutive SDUs (from same logical channel) if N is larger than 1.
A MS flag 390 could indicate whether the N field 380 is present or
not. In any case, each SDU would have its own LI 340 field.
[0067] The N field 380 could be configured for specific LCIDs 330.
The LCID 330 could unambiguously identify whether the N field 380
exists.
[0068] The LCID 330 may be omitted for the first SDU if this SDU is
a segment. The rationale is that the information should have been
present in a prior MAC-ehs PDU when the first segment was
transmitted. Alternatively, the LCID field 330 may be omitted for
the last SDU only if this SDU is a segment.
[0069] Instead of inserting a "SDU end" flag 350 for each SDU (or
segment thereof) or group of SDUs, a single "NTot" field (not
shown) for the whole SDSF field indicating the total number of SDU
or SDU segments in the payload for this priority queue can be
added. The size of this field depends on the maximum possible
number of SDUs per priority queue within a MAC-ehs PDU.
[0070] Several methods exist for indicating the length of each SDU
or segment thereof. Several embodiments exist for utilizing a LI
340 for every SDU or group or segment thereof. This embodiment
explains how to structure the LI field 340 to efficiently signal
the length of each SDU or group or segment thereof.
[0071] A LI 340 specifies the exact number of bits (or octets if it
is imposed that each SDU be octet-aligned) that the SDU or segment
thereof contains. This representation may be made using one of the
commonly known binary formats (e.g., with the most significant bit
(MSB) first or the least significant bit (LSB) first). The length
of the LI 340 field depends on the maximum possible length of a
SDU. Several possible options are possible for the length of the LI
340 field. In one option, the length of the LI 340 is
pre-determined and fixed regardless of the logical channel (LCD
field 330) and is the number of bits required to represent the
maximum SDU size (in bits or octets) across all logical channels,
regardless of any prior signaling to set the maximum SDU size for a
given RLC instance. In an alternative option, the length of the LI
340 depends on the logical channel (LCID) field 330 and is the
number of bits required to represent the maximum SDU size (in bits
or octets) for this logical channel. The maximum SDU size may vary
from one radio bearer instantiation to another and may change upon
reconfiguration or even dynamically. To avoid possible ambiguity,
the network may signal the receiver the size of the LI 340 field,
while at the same time it may also signal a change of maximum SDU
size.
[0072] Another variation includes mixed utilization of size
indicators (SID) (not shown) and LIs 340. A size indicator (SID) is
used by the transmitter whenever the length of the MAC-ehs SDU is
one of a pro-defined set of sizes. A size indicator is a field with
a small number of bits (e.g. 3) where each possible value
represents a pre-defined SDU size. Otherwise, if the SDU size is
not one of the set of pre-defined sizes, an LI 340 specifying the
exact number of bits or octets (in binary format) is used for the
case of non-octet-aligned SDUs. To allow the receiver to
distinguish between an SID and an LI 340, a flag of one bit is
inserted before either the SID or LI 340 field. Alternatively,
application of the SID is dependent on the configuration of the
LCID. In this case, use of SID or LI 340 is known based on the LCID
value. It should be noted that the number of bits of the SID field
does not need to be constant.
[0073] Minimization of the average number of bits needed to
represent the size(s) of the SDUs contained in a MAC-ehs PDU can be
achieved if the pre-defined set of sizes represented by the SIDs
corresponds to the set of sizes that are encountered the most
often. The mapping between a SID value and the corresponding SDU
size should be known by at least the transmitter and the receiver.
Several methods can be defined to determine a suitable mapping
between SID values and SDU sizes and to signal this mapping to the
receiver and/or transmitter.
[0074] One SID mapping method utilizes explicit radio network
controller (RNC)-based mapping. In this method, the RNC determines
the SID mapping and signals the mapping to both the base station
and the WTRU through Iub and RRC signaling respectively. Using this
method may be dependent on which LCID is present in the MAC-ehs
PDU. It may also be dependent on whether the RNC is required to
define a SID for every possible SDU size, wherein the base station
can utilize the LI if the size of the SDU that has to be inserted
is not one of the sizes mapped to the BID values. The RNC may
select SDU sizes that are occurring more frequently (or expected to
occur more frequently), such as (but not limited to) the maximum
RLC PDU size, the size of a status RLC PDU, or the RLC PDU size
that is observed to occur most often as seen by the RNC.
[0075] A second SID mapping method uses implicit mapping. In this
method, the mapping between the SID and the SDU sizes is not
signaled explicitly. Instead, a BID is implicitly assigned a
certain SDU size by a rule known by the transmitter and the
receiver. Examples of rules for SID mapping using this method
include assigning a SID value #n1 to the maximum RLC PDU size,
assigning a BID value #n2 to N, where N is a fixed value known to
occur frequently, regardless of the scenario (e.g., the typical
value of a status RLC PDU), or assigning a SID value #n3 to half
(or a portion, such as a third or a fourth) of the maximum RLC PDU
size, thus supporting segmentation in 2, 3 or 4 equal sizes.
[0076] A third SID mapping method uses base station-based mapping.
In this method, the mapping between an SID value and an SDU size is
determined based on observations of which SDU sizes tend to occur
most often. This mapping is communicated through MAC signaling. One
possible way of signaling the mapping is by using a "mapping" flag
defined to follow the LI. When the flag is set, the following bits
represent the SID value that the size represented by the LI will be
mapped to in subsequent MAC-ehs PDUs following successful reception
of this MAC-ehs PDU at the WTRU. Thus, the receiver waits for the
next time it receives an SDU of the size that it desires to assign
to a certain SID value. When the SDU is received and the MAC-ehs
PDU is built, the LI is utilized to signal the length of the SDU as
usual. The receiver sets the "mapping" flag and inserts the SID
value to be set after it. Upon correct reception of the MAC-ehs
PDU, the transmitter determines that the mapping flag is set and
assigns the new size to the SID value following it, discarding any
previously mapped size to this SID value.
[0077] Some specific embodiments that are possible for constraints
on MAC-ehs multiplexing are disclosed. These constraints may be
deemed necessary to satisfy the quality of service (QoS)
requirements (e.g., retransmission, latency, block error ratio
(BLER)) of the logical channels.
[0078] Multiplexing restrictions may be signaled on the Iub/Iur
interface in the UMTS Terrestrial Radio Access Network (UTRAN) with
control information specifying which priority queues can be
multiplexed. If priority queues are formed from multiplexing
logical channels, it can be determined which logical channels can
be multiplexed if MAC-ehs multiplexing is directly from the logical
channels (i.e., no priority queues are formed from logical channels
or when there is a one-to-one mapping between priority queues and
logical channels).
[0079] One application of the above MAC-ehs multiplexing
restriction could be that signaling radio bearers (SRBs) are not
multiplexed with non-signaling radio bearers. If SRBs are
multiplexed separately from non-SRBs, the TB size determination for
SRBs may be treated in the following manner. The RACH measurements
can be used to determine the TB sizes for MAC-ehs PDUs carrying
SDUs from SRBs and signaled to the MAC during configuration and
reconfiguration signaling from radio resource control (RRC).
[0080] FIG. 4 is a flow diagram of the operations 400 performed to
process the MAC-ehs PDUs and reconstruct the MAC-ehs SDUs. Upon
reception of the MAC-ehs PDU, the MAC-ehs PDU header is stripped
from the payload and split it into its sections at 405, utilizing
the "finish" flag to find where the header finishes. For each
header section (priority queue), the corresponding payload (SDUs
and fragments thereof) is extracted as indicated from the SDSF at
410, attaches it to the header section itself at 420 to build a
reordering "Queue PDU," 430 and inserts this Queue PDU into the
reordering queue corresponding to the reordering queue ID and the
TSN at 440. Alternatively, a PDU does not need to be built, but
rather the information contained in the header section (e.g., TSN,
SDSF) is extracted and associated with the corresponding payload
within the reordering queue at 425 so that reordering can be
performed in 450 and then disassembly and/or reassembly can be
performed. Following the reordering process at 450, a reassembly is
performed at 460. After reassembly at 460 is complete, the complete
MAC SDUs are delivered to the correct logical channel at 470.
[0081] Within each reordering queue, the reordering functionality
450 is performed such that the MAC-ehs PDUs are replaced by one or
more reordering Queue PDUs (or the set of TSN, SDSF and associated
payload) and the reordered PDUs are sent to a MAC SDU
disassembly/reassembly/demultiplexing unit (not shown) rather than
just a disassembly unit (not shown). Also, a queue-specific timer
(T1) (not shown) may be signaled. Each reordering queue may
optionally have a separate T1 timer.
[0082] FIG. 5 is a flow diagram of an example data processing
functionality 500 within each disassembly/reassembly/demultiplexing
unit. Reading the SDSF field, the data is processed within each
disassembly/reassembly/demultiplexing unit. The following describes
the operation for the data of TSN=n for this priority queue. As
shown in FIG. 5, every SDU or SDU segment is disassembled at 505,
utilizing the LI fields, the "SDU end" flag, and if applicable, the
N fields. If the FSS flag is set to segment at 510 and if the data
of TSN=n-1 for this priority queue has been previously delivered to
this disassembly/reassembly/demultiplexing unit at 520, the SDU
segment (first SDU of the payload for this priority queue) is
reassembled with segments of previous PDUs stored in the reassembly
unit at 530. A determination is made at 540 whether the number of
SDUs or SDU segments is larger than 1 or if the FSE flag is set to
"Full." If the number of SDUs or SDU segments is larger than 1, or
if the FSE flag is set to "Full," the first SDU of the reordering
PDU was the last segment of the MAC SDU and the completely
reassembled SDU is delivered to the higher layer at the service
access point corresponding to the logical channel indicated by the
LCID field at 550. If the number of SDU or SDU segments is less
than 1 and if the FSE flag is set to "segment," the SDU is a middle
segment of the reordering PDU and the reassembled segments are
stored and the procedure ends for that reordering queue PDU at
545.
[0083] If the FSS flag is set to "segment" at 510 and the data of
TSN=n-1 for this priority queue has not been previously delivered
(e.g., if the T1 timer has expired) at 520, the SDU segment is
discarded and previous SDU segments of previous PDUs stored in the
reassembly unit at 525. A determination at 580 is then performed to
determine whether greater than 1 SDU segment has been extracted. If
greater than 1 SDU or SDU segment has been extracted, the receiver
delivers the extracted SDUs that are between the first SDU or SDU
segment and the last SDU or SDU segment to the higher layer at the
service access point corresponding to the logical channels
indicated by the respective LID fields at 570. If the FSE flag is
set to "segment," the segment is a first segment of a MAC-ehs SDU,
the receiver discards any segment from a previous PDU stored in the
reassembly unit and inserts the last SDU segment into the
reassembly unit at 590. If the FSE flag is set to "full," the last
payload unit is a complete MAC-ehs SDU and the receiver delivers
the last SDU to the higher layer at the service access point
corresponding to the logical channel indicated by the LCID field at
595.
[0084] If the FSS flag is set to segment at 510 and the data of
TSN=n-1 for this priority queue has been previously delivered at
520, the SDU segment is reassembled with the previously stored PDU
segment. If it is determined at 540 that the SDU or SDU segment is
greater than 1 or that the FSE flag is set to "full," the receiver
delivers the completely reassembled SDU to the higher layer at the
service access point corresponding to the logical channel indicated
by the LCID field at 550. A determination at 580 is then performed
to determine whether greater than 1 SDU segment has been extracted.
If greater than 1 SDU or SDU segment has been extracted, the
receiver delivers the extracted SDUs that are between the first SDU
or SDU segment and the last SDU or SDU segment to the higher layer
at the service access point corresponding to the logical channels
indicated by the respective LCID fields at 570. If the FSE flag is
set to "segment," the segment is a first segment of a MAC-ehs SDU
the receiver discards any segment from a previous PDU stored in the
reassembly unit and inserts the segment into the reassembly unit at
590. If the FSE flag is set to "full," the receiver delivers the
last SDU to the higher layer at the service access point
corresponding to the logical channel indicated by the LCID field at
595. If it is determined at 540 that the SDU or SDU segment is less
than 1 or that the FSE flag is set to "segment," the packet is
combined and stored, and the procedure ends at 545.
[0085] When the FSS flag is set to "full" at 510 and FSE is not set
to "segment" and the first payload unit is a complete SDU and the
first SDU is delivered to the higher layer at the service access
point corresponding to the logical channel indicated by the LCID
field at 560. A determination at 580 is then performed to determine
whether greater than 1 SDU segment has been extracted. If greater
than 1 SDU or SDU segment has been extracted, the receiver delivers
the extracted SDUs up to the last SDU or SDU segment to the higher
layer at the service access point corresponding to the logical
channels indicated by the respective LCID fields at 570. If the FSE
flag is set to "segment," the receiver discards any segment from a
previous PDU stored in the reassembly unit and inserts the last SDU
segment into the reassembly unit at 590. If the FSE flag is set to
"full," the receiver delivers the last SDU to the higher layer at
the service access point corresponding to the logical channel
indicated by the LCID field at 595.
[0086] In another embodiment, a modification to the baseline header
can be introduced to more efficiently support logical channel(s) to
which a pre-defined set of RLC sizes apply, i.e., that are not used
by RLC instances configured with the flexible RLC PDU size
available in 3GPP Release 7. For instance, these channels could be
used by AM RLC instances configured with fixed PDU size, or
unacknowledged mode (UM) RLC instances configured with fixed PDU
sizes.
[0087] FIG. 6 is the parts of the header 600 describing SDU(s)
belonging to the concerned logical channels to allow efficient
multiplexing of different types of logical channels in the same
MAC-ehs PDU. The modifications described in this embodiment can
affect only the parts of the header 600 that describe SDU(s)
belonging to the concerned logical channels. In other words, if
there are other logical channels multiplexed in the same MAC-ehs
PDU, to which flexible PDU size applies, the parts of the header
corresponding to these logical channels may still follow the
baseline header or any improvement of the baseline header
applicable to these channels. This allows efficient multiplexing of
different types of logical channels in the same MAC-ehs PDU. In
this example, only the logical channel identified by LCH-ID2 610 is
used by an RLC instance configured with fixed PDU size(s). The
modifications described below apply only to its associated fields
620 (indicated in bold in FIG. 6). This part of the header 600 will
be referred to hereafter as "header part."
[0088] There are multiple options for this embodiment. Option 1
does not allow segmentation for the concerned logical channel, but
is simpler. Options 2a and 2b allow segmentation.
[0089] FIG. 7 is a configuration for the header 700 describing
SDU(s) belonging to the concerned logical channels to allow
efficient multiplexing of different types of logical channels in
the same MAC-ehs PDU. Option 1 does not allow for segmentation for
logical channels to which fixed PDU size(s) apply. The header part
immediately following the logical channel ID 710 includes the
following fields, not necessarily in order. Optionally, a
transmission sequence number (TSN) 720 follows the logical channel
ID 710. This field may not be required when the previous logical
channel in the header is utilizing the same reordering queue.
Optionally, a field flag (Fh) 730 may follow indicating whether
this is the last set of MAC-ehs payload units of the header. This
field may not be required where the end of the header is determined
by comparing the size of the MAC-ehs PDU to the sum of sizes of
payload units decoded so far. Alternatively, this field may also be
used to indicate the end of a priority queue.
[0090] The header 700 usually includes a field (N) 740 indicating a
number of concatenated SDUs of the same size from the logical
channel. In one option, a field (SID) 750 indicating the size of
the SDU(s) whose number is indicated in the previous field may be
included. An optional "finish" (Fc) flag 760 indicating whether the
part of the header corresponding to this logical channel is
completed may be included. If this flag is present and indicates
that the header is not complete, an additional set of (N, SID, Fc)
fields follow for this logical channel to indicate another group of
N SDUs with size indicated by the SID field. In another option,
padding bits 770 as required for maintaining byte-alignment of the
header may be included. These padding bits could instead be present
at the very end of the header in case SDUs from multiple logical
channels are multiplexed in the MAC-ehs PDU.
[0091] For logical channels to which a single fixed RLC PDU size
applies, such as logical channels used by AM RLC instances, the Fc
field (finish flag) 760 could be omitted, since it is known in
advance that there will not be another group of SDUs with different
sizes. Furthermore, if in addition the size itself is known, the
SID field 750 could also be omitted.
[0092] Examples of alternate configurations are illustrated in
FIGS. 8 and 9. The components shown in FIGS. 8 and 9 correspond to
the components in FIG. 7. FIG. 8 is a header 800 example where the
LCH-ID includes single fixed RLC PDU sizes. FIG. 9 is a header 900
example where MAC-ehs SDUs from two logical channels are
multiplexed together. One logical channel is used by an RLC
instance configured with flexible RLC PDU size, while the other
logical channel is used by an RLC instance configured with a single
fixed RLC PDU size. In this example, the two logical channels 910
and 915 are not in the same priority queue, hence the TSN field 920
is present for both.
[0093] Option 2a allows segmentation for logical channels to which
fixed PDU sizes apply. With this option, the header part
immediately following the logical channel ID includes a 1-bit flag
field (Ff) (not shown) indicating whether the following fields are
"N" and "SID" as described in Option 1. If this flag indicates that
"N" and "SID" are present, the rest of the header part is
interpreted as in Option 1.
[0094] If the Ff flag does not indicate that "N" and "SID" are
present, a segmentation indication (SI) field 980 indicating the
segmentation status of the payload may be included. For instance,
this field could indicate if the first payload unit is a segment
and if the last payload unit is a segment. When a single payload
unit is allowed, the field indicates whether the payload unit is a
complete SDU or the starting segment, middle segment, or final
segment of the SDU. The SI field 980 may not be present if it is
already indicated in a previous header part for a logical channel
that is multiplexed on the same priority queue as this logical
channel. In one option, a TSN 920 may be included. This field may
not be required in case the previous logical channel in the header
is utilizing the same reordering queue.
[0095] Optionally, a field flag (Fh) indicating whether this is the
last set of MAC-ehs payload units of the header may be included.
This field may not be required in case the end of the header is
determined by comparing the size of the MAC-ehs PDU to the sum of
sizes of payload units decoded so far. Alternatively, this field
may also be used to indicate the end of a priority queue.
[0096] In another option, a length indicator (LI) 990 indicating
the length of the payload unit for this logical channel may be
included. As will be described in another embodiment, this field
may not be required if this payload unit is a segment and is at the
end of the MAC-ehs PDU. The LI 990 may also be used to indicate a
group of payload units (e.g., complete SDUs possibly followed by a
segment of SDUs) in case a single fixed PDU size applies to the
logical channel (e.g., if it is used by an AM RLC entity with fixed
RLC PDU size) and provided that the transmitter knows about this
size. This is accomplished by having the LI 990 indicate the total
number of bytes from the group of payload units. The individual
payload units are determined by performing an integer division of
the LI 990 value by the known fixed RLC PDU size. The result is the
number of complete SDUs, and the remainder of the division is the
size of the SDU segment at the end. In another configuration,
padding bits 970 as required for maintaining byte-alignment of the
header may be included. These padding bits 970 could instead be
present at the very end of the header in case SDUs from multiple
logical channels are multiplexed in the MAC-ehs PDU.
[0097] Option 2b allows for segmentation for logical channels to
which fixed PDU size(s) apply. This option may be used when the SI
field 980 is indicated once per priority queue. With this option,
the header part immediately following the logical channel ID 910
may include a 1-bit flag field (Ff) (not shown) indicating whether
the payload unit(s) is/are the last of the priority queue onto
which the logical channel is multiplexed. This flag may not be
required if it is known otherwise that the payload unit(s) is/are
the last of the priority queue (e.g., using other fields in
previous header parts).
[0098] If this is not the last payload unit(s) of the priority
queue, or if the SI field 980 applicable to this priority queue
indicates that the last payload unit of this priority queue is not
a segment, then the rest of the header part is interpreted as in
Option 1.
[0099] If this is the last payload unit(s) of the priority queue,
or if the SI field 980 applicable to this priority queue indicates
that the last payload unit of this priority queue is a segment, a
LI 990 indicating the length of the payload unit for this logical
channel may be included. As will be described in another
embodiment, this field may not be required if this payload unit is
a segment and is at the end of the MAC-ehs PDU. The LI 990 may also
be used to indicate a group of complete SDUs possibly followed by a
segment of SDUs in case a single fixed PDU size applies to the
logical channel, as described in Option 2a. In another
configuration, padding bits 970 as required for maintaining
byte-alignment of the header may be included. These padding bits
970 could instead be present at the very end of the header in case
SDUs from multiple logical channels are multiplexed in the MAC-ehs
PDU.
[0100] With the introduction of optimized MAC-ehs headers, a new
definition for SI has been proposed. However, the proposed scheme
does not properly handle the distinction between multiple and
single payload units within the reordering PDU. When a single
payload unit is present in the reordering PDU, it is ambiguous
which SI indication should be used. In the proposed SI structure,
"10" corresponds to the first payload unit being a complete unit,
and if more than one payload unit is present in the reordering PDU,
the last payload is a segment. With this definition, if only one
payload unit is present, then it will be a complete MAC-ehs PDU,
however it should be a segment that corresponds to the first
segment of a MAC-ehs PDU. Moreover, when SI is equivalent to "11,"
the definition corresponds only to multiple payload units. When
setting the SI fields, the transmitter must know exactly what to
indicate, when a single payload unit is present in the reordering
PDU. Since a single payload unit can correspond to a first, middle,
last, or complete MAC-ehs SDU, the transmitter shall specify the
correct SI indication so that the segments can be correctly
reassembled. More specifically, the following changes and/or
interpretation of the SI field may be considered to specifically
cover the scenario where the reordering PDU contains only one
payload unit.
[0101] FIG. 10 and Table 2 show a modified method 1000 for
interpretation of the SI field where the reordering PDU contains
only one payload unit. All of the SDUs of the reordering PDU are
complete MAC PDUs when the SI is equal to "00" (not shown). As
shown in FIG. 10, when SI is equal to "01" at 1002, the first
payload unit of the reordering PDU is a segment and it corresponds
to the last segment of a MAC-ehs SDU (MAC-ehs SDU is used
interchangeably with MAC-d PDU) at 1007. This is applicable to a
single payload unit 1005 or multiple payload units 1010 in the PDU.
If there is more than one payload unit, the last payload unit is a
complete MAC-ehs SDU at 1009.
[0102] When SI is equal to "10" at 1012, if there is more than one
payload unit in the reordering PDU, then the first payload unit is
a complete MAC-ehs SDU at 1019. The last payload unit of the
reordering PDU is a segment of a MAC-ehs SDU and it corresponds to
the first segment of the MAC-ehs SDU at 1019. This corresponds to
the case where there is a single payload unit or multiple payload
units in the reordering PDU at 1017 and 1019.
[0103] When SI is equal to "11" at 1022, the first payload unit is
a segment of a MAC-ehs SDU at 1027. Note that this segment can be a
last segment of a MAC-ehs SDU (when there are multiple payload
units) or it can be a middle segment if there is only one payload
unit in the reordering PDU. For example, if there are multiple
payload units at 1027, the segment is a last segment of the MAC-ehs
SDU. If there is a single payload unit at 1027, the segment is a
middle segment of a MAC-es SDU. If there are multiple payload
units, then the last payload unit is a segment at 1029. This
segment will be the first segment of MAC-ehs SDU at 1029.
[0104] Table 2 shows the encoding of the SI field as described
above, where the terminology MAC PDU corresponds to a MAC-c/d PDU
or a MAC-ehs SDU. A SDU is the equivalent of a reordering SDU or a
MAC-ehs SDU or segment thereof.
TABLE-US-00002 TABLE 2 SI Field Segmentation indication 00 The
first SDU of the reordering PDU is a complete MAC PDU. The last SDU
of the reordering PDU is a complete MAC PDU. 01 The first SDU of
the reordering PDU is a last segment of a MAC PDU. If there is more
than one SDU in the reordering PDU, the last SDU of the reordering
PDU is a complete MAC PDU. 10 If there is more than one SDU in the
reordering PDU, the first SDU of the reordering PDU is a complete
MAC PDU. The last SDU of the reordering PDU is a first segment of a
MAC PDU. 11 If there is more than one SDU in the reordering PDU,
the first SDU is the last segment of a MAC PDU and the last SDU of
reordering PDU is a first segment of a MAC PDU. If there is a
single SDU in the reordering PDU the segment is a middle segment of
a MAC PDU
[0105] The following embodiment provides improved signaling of
segmentation. This embodiment describes a method of encoding the
bits of the SI field 980 when the SI field 980 is present once per
priority queue. There are two options, one applying to the 2-bit SI
field and the other for the 1-bit SI field.
[0106] As shown in FIG. 11 and Table 3 below, a 2-bit SI field can
be used as one possible encoding for minimizing overhead. It should
be understood that the exact choice of bit combinations for each
value is arbitrary and could be changed provided that two values
are assigned the same bit combination. Table 3 shows an example of
improved signaling of the segmentation indication field.
TABLE-US-00003 TABLE 3 SI Field Segmentation indication Value #1
The first payload unit of the addressed set of payload units is a
complete (e.g., 00) MAC-ehs (or MAC-is) SDU. The last payload unit
of the addressed set of (1110) payload units is a complete MAC-e/hs
(or MAC-is) SDU. (1120) Value #2 The first payload unit of the
addressed set of payload units is a complete (e.g., 10) MAC-ehs (or
MAC-is) SDU or the first segment of a MAC-ehs (or MAC-is) (1130)
SDU. The last payload unit of the addressed set is a segment of a
MAC-ehs (or MAC-is) SDU. (1140) Value #3 The first payload unit of
the addressed set of payload units is a segment of a (e.g., 01)
MAC-ehs (or MAC-is) SDU. The last payload unit of the addressed set
of (1150) payload units is a complete MAC-ehs (or MAC-is) SDU or
the last segment of a MAC-ehs (or MAC-is) SDU. (1160) Value #4 The
first payload unit of the addressed set of payload units is a
middle (e.g., 11) segment or a last segment of a MAC-ehs (or
MAC-is) SDU. The last (1170) payload unit of the addressed set of
payload units is the first segment or a middle segment of a MAC-ehs
(or MAC-is) SDU. (1180)
[0107] The advantage of the encoding depicted in Table 3 is that in
case the addressed set of MAC-ehs payload unit(s) are of a single
SDU segment, the determination can be based on the SI field and
whether this SDU segment completes the SDU or not. Otherwise, the
determination is based on the presence of padding bits, and there
can even be ambiguity if the last segment exactly fits into the
remaining available payload.
[0108] In addition, the encoding shown in Table 3 is more robust to
missing MAC-ehs PDUs. For example, where a MAC-ehs PDU of TSN #n
for a given priority queue is missing, and the first payload unit
for the MAC-ehs PDU of TSN #n+1 is a segment, the original encoding
did not allow determining whether the first payload unit is a first
or middle segment. In the latter case, the payload unit would have
to be discarded since the first part of the SDU is missing. The new
encoding fixes this issue by differentiating between the two
cases.
[0109] FIG. 12 is a flow diagram of an alternative method 1200 of
formulating the encoding where the SI field may be defined as shown
in Table 4. Table 4 shows an alternative formulation for improved
signaling of the segmentation indication field. This formulation is
completely equivalent to the one shown in Table 3, but may be
easier to understand. This is achieved by separating the cases
according to whether there is a single payload unit or multiple
payload units in the addressed set.
TABLE-US-00004 TABLE 4 Segmentation indication (1215, 1235, 1255,
1275) Single MAC-ehs (or MAC-is) payload unit in addressed Multiple
(>1) MAC-ehs (or MAC-is) payload SI Field set units in addressed
set Value #1 The MAC-ehs (or MAC- The first MAC-ehs (or MAC-is)
payload unit of the (e.g. 00) is) payload unit is a addressed set
is a complete MAC-ehs (or MAC-is) (1210) complete MAC-ehs (or SDU.
The last MAC-ehs (or MAC-is) payload unit of MAC-is) SDU (1220) the
addressed set is a complete MAC-ehs (or MAC- is) SDU. (1225) Value
#2 The MAC-ehs (or MAC- The first MAC-ehs (or MAC-is) payload unit
of the (e.g. 10) is) payload unit is the addressed set is a
complete MAC-ehs (or MAC-is) (1230) first segment of a MAC- SDU.
The last MAC-ehs (or MAC-is) payload unit of ehs (or MAC-is) SDU
the addressed set is the first segment of a MAC-ehs (1240) (or
MAC-is) SDU. (1245) Value #3 The MAC-ehs (or MAC- The first MAC-ehs
(or MAC-is) payload unit of the (e.g. 01) is) payload unit is the
addressed set is the last segment of a MAC-ehs (or (1250) last
segment of the MAC- MAC-is) SDU. The last MAC-ehs (or MAC-is) ehs
(or MAC-is) SDU payload unit of the addressed set is a complete
(1260) MAC-ehs (or MAC-is) SDU. (1265) Value #4 The MAC-ehs (or
MAC- The first MAC-ehs (or MAC-is) payload unit of the (e.g. 11)
is) payload unit is a addressed set is the last segment of a
MAC-ehs (or (1270) middle segment of the MAC-is) SDU. The last
MAC-ehs (or MAC-is) MAC-ehs (or MAC-is) payload unit of the
addressed set is the first SDU (1280) segment of a MAC-ehs (or
MAC-is) SDU. (1285)
[0110] With the proposed type of encoding, the reassembly function
would be modified as follows, such that the choice of the SI field
values would correspond to the examples shown in Table 4. The
"reordering PDU" referred to in the following procedure refers to a
set of MAC-ehs payload units that belong to the same priority
queue. Also note that the term "output entity" may refer to a
de-multiplexing entity, or layer/sub-layer above the MAC-ehs, or
any other entity that the reassembly unit delivers SDUs to.
[0111] The SI field can be used to determine if a segment is a
start or middle segment. Several cases can be distinguished
depending on the number of bits of the SI field and whether it is
present once for each priority queue or present for every SDU or
segment thereof.
[0112] A first example is a 2-bit SI, one SI per priority queue,
where the encoding is per the embodiments described in either of
Tables 3 or 4. In this example, the bit combination indicates if
the last SDU or SDU segment of the addressed set of the priority
queue is a start or middle segment of an SDU.
[0113] A second example is a 2-bit SI, one SI for each SDU or SDU
segment encoding as shown in either of Tables 3 or 4. In this
example, the bit combination indicates if the SDU or SDU segment is
a start or middle segment of a SDU.
[0114] FIG. 13 is a flow diagram of the reassembly unit processes
1300 for the SI field associated with a reordering PDU. If the SI
field is set to "0" to indicate that the first and last MAC-ehs
payload units of the set are complete MAC-ehs SDUs at 1310, all
MAC-ehs SDUs corresponding to MAC-ehs payload units in the set are
delivered to the output entity at 1315.
[0115] If at 1320, the SI field is set to "01" to indicate that the
first MAC-ehs payload unit is a segment of a MAC-ehs SDU, but the
last MAC-ehs payload unit is a complete MAC-ehs SDU or is the last
segment of a MAC-ehs SDU, a determination of whether the received
and stored MAC-ehs payload units are consecutive can be made at
1325. If the received and stored MAC-ehs payload units are
consecutive, the first received MAC-ehs payload unit is combined
with the stored MAC-ehs SDU and the MAC-ehs SDU corresponding to
the combined MAC-ehs payload unit is delivered to the output entity
at 1330. If the received and stored MAC-ehs payload units are not
consecutive, the received and stored MAC-ehs payload unit are
discarded and all the MAC-ehs SDUs corresponding to subsequent
MAC-ehs payload units in the set are delivered to the output entity
at 1335.
[0116] If, at 1340, the SI field is set to "10" to indicate that
the last MAC-ehs payload unit is a segment of a MAC-ehs SDU, but
the first is a complete MAC-ehs SDU or the first segment of a
MAC-ehs SDU, all the MAC-ehs SDUs corresponding to all but the last
MAC-ehs payload unit in the set are delivered to output entity and
any previously stored MAC-ehs payload unit are discarded while the
last MAC-ehs payload unit of the received reordering PDU is stored
at 1346.
[0117] If at 1350, the SI field is set to "11" to indicate that the
first MAC-ehs payload unit is a middle segment of a last segment of
a MAC-ehs SDU and the last MAC-ehs payload unit is the first
segment or a middle segment of a MAC-ehs SDU, a determine of
whether the received and stored MAC-ehs payload units are
consecutive can be made at 1355. If the received and stored MAC-ehs
payload units are consecutive, the first received MAC-ehs payload
unit is combined with the stored MAC-ehs payload unit at 1360. If
there are several MAC-ehs payload units in the set, the MAC-ehs SDU
corresponding to the combined MAC-ehs payload unit is delivered to
output entity, all the MAC-ehs SDUs corresponding to all but the
last MAC-ehs payload unit in the set are delivered to output
entity, and any previously stored MAC-ehs payload unit is discarded
while the last MAC-ehs payload unit of the received reordering PDU
is stored at 1365. If the received and stored MAC-ehs payload units
are not consecutive, the received and stored MAC-ehs payload units
are discarded at 1370.
[0118] In order to reflect these definitions, one possible
alternate of updating the table with the structure of the SI field
is shown in Table 4. Table 4 is a formulation of the SI field that
is equivalent to that of Table 3. Tables 2, 3 and 4 are presented
as alternate but equivalent formulations of the solution for the
redefinition of the SI field for the 2-bits case.
[0119] The reassembly functionality should perform reassembly based
on one of the descriptions disclosed herein. If the reassembly
function is described such that it takes into account those
definitions, the transmitter may optionally not require knowledge
of what the SI field indicates. The receiver is responsible for
assigning the right SI indication for every reordering PDU, such
that the transmitter can perform reassembly correctly based on the
value of the SI field.
[0120] The definitions described above can be used regardless of
the definitions defined in the 3GPP specifications. For example,
the SI structure can remain unchanged, but proprietary solutions
take into account the correct setting of the SI as described above,
such that the reassembly function may work correctly.
[0121] When SI is equivalent to "11," the reassembly procedure
described above proceeds to discard SDUs that it should not be
discarding. More specifically, when the received and stored MAC-ehs
SDUs are not consecutive, both of the SDUs are discarded. This
implies that all the remaining payload units in the received
reordering PDUs are discarded and/or not processed correctly.
[0122] FIG. 14 is a flow diagram of how the reassembly unit may
perform a combining function when SI is equivalent to "11," to
avoid this issue. A determination of whether the first received and
stored payload units are consecutive is made at 1410. The first
received and stored payload unit should be combined if the payload
units are consecutive at 1420. The combined packet should only be
delivered to higher layers 1430 if the reordering PDU contains
multiple payload units at 1425, since in that scenario the first
payload unit corresponds to the last segment of the MAC-ehs SDU.
Otherwise, if there is only one payload unit in the reordering PDU,
the segment is a middle segment and thus the combined packet should
be stored at 1440.
[0123] When SI is equivalent to "11," the reassembly unit may
perform a discarding function as shown in FIG. 14. If the payload
units are not consecutive at 1410, the stored payload unit and the
first received payload unit (first segment in the reordering PDU or
the only payload unit) should be discarded at 1450. All other
payload units should be processed such that if there are multiple
payload units in the reordering PDU at 1460.
[0124] FIG. 15 is a flow diagram of how the remaining payload units
in 1460 of FIG. 14 are processed if there are multiple payload
units in the reordering PDU. If there are multiple payload units in
the reordering PDU at 1510, all but the last complete MAC-ehs SDUs
must be forwarded to higher layers (or output entity) at 1520. Note
that it is assumed that the first payload unit has already been
combined or discarded. The last payload unit, which corresponds to
the first segment of a SDU should be stored in the reassembly unit
at 1530. If the PDU does not contain multiple payload units, the
stored payload unit and the received payload unit are combined and
stored. This is shown in FIG. 14 at 1440. FIG. 16 is a flow diagram
of the combined reassembly process shown in FIGS. 14 and 15.
[0125] In order to reflect the definitions of SI and descriptions
of the reassembly function described above, the reassembly unit
functionality can possibly be updated in the following way. Note
that the changes include the fact that the interpretation of the SI
field need not be known, but that it might be optionally added to
the description. The terms MAC-d and MAC-c PDUs are used
interchangeably with MAC PDUs and MAC-ehs SDU, and MAC-ehs SDU is
used interchangeably with payload units.
[0126] FIG. 17 is a flow diagram of how the reassembly unit
processes 1700 the SI field associated with a reordering PDU. If
the SI field is set to "0" at 1710, all the MAC-d PDUs
corresponding to MAC-ehs SDUs in the set are delivered to higher
layers at 1720.
[0127] If the SI field is set to "01" at 1730, the determination of
whether the received and stored MAC-ehs SDUs are consecutive is
made at 1735. If the received and stored MAC-ehs SDUs are
consecutive, the first received MAC-ehs SDU is combined with the
stored MAC-ehs SDU and the MAC-d PDU corresponding to the combined
MAC-ehs SDU is delivered to higher layers (or output entity) at
1740. If the received and stored MAC-ehs SDUs are not consecutive,
the received and stored MAC-ehs SDU are discarded while all the
MAC-d PDUs corresponding to subsequent MAC-ehs SDUs in the set are
delivered to higher layers (or output entity) at 1745.
[0128] If the SI field is set to "10" at 1750, all the MAC-d PDUs
corresponding to all but the last MAC-ehs SDU in the set are
delivered to the higher layers (or output entity) and any
previously stored MAC-ehs SDU is discarded while the last MAC-ehs
SDU of the received reordering PDU is stored at 1760.
[0129] If the SI field is set to "11" at 1770, a determination of
whether the received and stored MAC-ehs SDUs are consecutive can be
made at 1775. If the received and stored MAC-ehs SDUs are
consecutive, the first received MAC-ehs SDU is combined with the
stored MAC-ehs SDU at 1780. If the received and stored MAC-ehs SDUs
are not consecutive, the first received MAC-ehs SDU and the stored
MAC-ehs SDU are discarded at 1785. If there are several MAC-ehs
SDUs in the set, the MAC-d PDU corresponding to the combined
MAC-ehs SDU is delivered to higher layers (or output entity), all
the MAC-d PDUs corresponding to all but the last MAC-ehs SDU in the
set are delivered to higher layers (or output entity), and the last
MAC-ehs SDU of the received reordering PDU is stored at 1790. This
procedure is essentially equivalent to the procedure described in
[0054].
[0130] When a 1-bit SI field is used on a per-MAC-ehs payload unit
basis, an encoding that would present the same advantage as the
previous one is shown in Table 5. The following example, shown in
Table 5, is a 1-bit SI, one SI for each SDU or SDU segment
encoding. In this example, the bit indicates whether the payload
unit is a start or middle segment of an SDU.
TABLE-US-00005 TABLE 5 SI Field Segmentation indication 0 The
MAC-ehs payload unit is a complete MAC-ehs SDU or the last segment
of a MAC-ehs SDU 1 The MAC-ehs payload unit is the first segment or
a middle segment of a MAC-ehs SDU.
[0131] It should be noted that the term "reordering PDU" may also
be used in place of "MAC-ehs payload unit" in this case, since
there would be a single MAC-ehs payload unit per reordering
PDU.
[0132] Another embodiment shows how it is possible to omit
including the LI field. As the size of this field could be
significant (e.g., 11 bits for byte-aligned payload), its relative
overhead could be significant in situations where the MAC-ehs PDU
is not very large (e.g., less than 1000 bits).
[0133] The principle of this embodiment is to omit the LI for the
last payload unit included in the MAC-ehs PDU if it is a segment of
a SDU which is not the last segment (i.e., a start segment or a
middle segment). The presence of a start or middle segment at the
end of the payload implies that there is no padding. Hence, when
processing the MAC-ehs PDU, the segment length to extract does not
need to be indicated, as the end of the segment corresponds to the
end of the MAC-ehs PDU.
[0134] Different methods can be used to indicate in the header if
this situation applies and therefore, whether a LI is present or
not. Method 1 describes an implicit indication of the presence of
the LI field. In this method, no specific field is added to the
header to indicate the presence or absence of the LI field. The
segmentation indication (SI) relied on is applicable to the last
priority queue or the last SDU as well as any other method or field
to determine the end of the header.
[0135] The methods to indicate the end of the header can include
adding a flag field (FQ or other) indicating if the header part is
the last of the header. If this option is included in the method,
the flag field would have to be present before the LI. Another
alternative method would be to calculate the difference between the
size of the MAC-ehs PDU and the sum of the lengths of the payload
unit(s) decoded from the header thus far to determine whether the
header is too small to accommodate an additional payload unit.
[0136] Method 2 describes an explicit indication of the presence of
the LI field. In this method, a flag (Fli) is present after the
logical channel identity to indicate whether a LI is present or not
for the payload units that are from this logical channel.
[0137] The presence of this field could be defined on a logical
channel basis and signaled by a higher layer. Alternatively, the
presence of the field could be determined by a pre-determined rule
relative to the nature of the logical channel. For instance, it
could make sense to limit this field to logical channels to which a
single fixed RLC PDU size apply (such as when it is used by an AM
RLC instance with fixed RLC PDU size), or a set of fixed RLC PDU
sizes apply (such as when it is used by an UM RLC instance with a
set of fixed RLC PDU sizes).
[0138] The reason the above-mentioned rules would be useful is that
the relative overhead of the LI in the case of a logical channel to
which flexible RLC PDU sizes apply is typically very small, thus
the omission of the length field is not necessary.
[0139] Although the features and elements are described 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 may be implemented in a computer program, software,
or firmware tangibly embodied 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).
[0140] 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.
[0141] 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) module.
* * * * *