U.S. patent application number 15/223721 was filed with the patent office on 2016-11-17 for methods and apparatus for reordering data in an evolved high speed packet access system.
This patent application is currently assigned to InterDigital Technology Corporation. The applicant listed for this patent is InterDigital Technology Corporation. Invention is credited to Christopher R. Cave, Rocco Di Girolamo, Paul Marinier, Diana Pani, Stephen E. Terry.
Application Number | 20160337026 15/223721 |
Document ID | / |
Family ID | 39638692 |
Filed Date | 2016-11-17 |
United States Patent
Application |
20160337026 |
Kind Code |
A1 |
Marinier; Paul ; et
al. |
November 17, 2016 |
METHODS AND APPARATUS FOR REORDERING DATA IN AN EVOLVED HIGH SPEED
PACKET ACCESS SYSTEM
Abstract
Method and apparatus for receiving high speed downlink shared
channel (HS-DSCH) transmissions are disclosed. An HS-DSCH medium
access control (MAC-ehs) entity receives MAC-ehs protocol data
units (PDUs) via a high speed downlink shared channel (HS-DSCH)
while in one of Cell_FACH, Cell_PCH, and URA_PCH states. The
reordering PDUs included in the MAC-ehs PDUs may be sent to a next
processing entity without performing reordering of the PDUs. A
certain reordering queue may enter a suspend state upon occurrence
of a triggering event and MAC-ehs PDUs distributed to the
reordering queue in the suspend state may be forwarded to the next
processing entity without performing reordering. MAC-ehs reset
procedure may be extended for a certain transmission such that the
MAC-ehs reset is performed after receiving a MAC-ehs PDU in a
target cell.
Inventors: |
Marinier; Paul; (Brossard,
CA) ; Pani; Diana; (Montreal, CA) ; Cave;
Christopher R.; (Dollard-des-Ormeaux, CA) ; Di
Girolamo; Rocco; (Laval, CA) ; Terry; Stephen E.;
(Northport, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InterDigital Technology Corporation |
Wilmington |
DE |
US |
|
|
Assignee: |
InterDigital Technology
Corporation
Wilmington
DE
|
Family ID: |
39638692 |
Appl. No.: |
15/223721 |
Filed: |
July 29, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14186447 |
Feb 21, 2014 |
9438330 |
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15223721 |
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12048855 |
Mar 14, 2008 |
8724634 |
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14186447 |
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60895028 |
Mar 15, 2007 |
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60895835 |
Mar 20, 2007 |
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60915023 |
Apr 30, 2007 |
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60916993 |
May 9, 2007 |
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60940209 |
May 25, 2007 |
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60941465 |
Jun 1, 2007 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 1/1861 20130101;
H04B 7/155 20130101; H04L 1/1841 20130101; H04L 47/6275 20130101;
H04W 16/26 20130101 |
International
Class: |
H04B 7/155 20060101
H04B007/155; H04W 16/26 20060101 H04W016/26; H04L 12/865 20060101
H04L012/865; H04L 1/18 20060101 H04L001/18 |
Claims
1. A method for a wireless transmit/receive unit (WTRU) to process
data, the method comprising: receiving data via a high speed
downlink shared channel (HS-DSCH); and sending the data to a next
processing entity without performing reordering of the reordering
PDUs if a condition has been met.
2. The method of claim 1, wherein the data comprises an HS-DSCH
medium access control (MAC-ehs) protocol data unit (PDU) including
a reordering PDU.
3. The method of claim 1, wherein the WTRU is in one of a Cell FACH
state, a Cell_PCH state, or a URA_PCH state.
4. The method of claim 2, wherein a single hybrid automatic repeat
request (HARQ) process is used for receiving the MAC-ehs PDU.
5. The method of claim 4, wherein each MAC-ehs PDU is received more
than once and each MAC-ehs PDU retransmission is completed before
starting reception of a subsequent MAC-ehs PDU.
6. The method of claim 1, wherein the condition has been met if the
data is from a certain priority queue.
7. The method of claim 2, wherein the condition has been met if the
received MAC-ehs PDU is associated with a common HS-DSCH radio
network temporary identity (H-RNTI).
8. The method of claim 1, wherein the condition has been met if the
data is from a certain logical channel.
9. The method of claim 8, wherein the certain logical channel is
one of a broadcast control channel (BCCH) or a paging control
channel (PCCH).
10. The method of claim 2, wherein the received MAC-ehs PDU is
received while the WTRU is in one of a Cell_FACH state, Cell_PCH
state, or URA_PCH state, and further comprising setting an initial
value of a next_expected_TSN to a lower edge of a receive window
(RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1).
11. A wireless transmit/receive unit (WTRU) comprising: a
transceiver; and a processor configured to: receive data via a high
speed downlink shared channel (HS-DSCH); and send the data to a
next processing entity without performing reordering of the
reordering PDUs if a condition has been met.
12. The WTRU of claim 11, wherein the data comprises an HS-DSCH
medium access control (MAC-ehs) protocol data unit (PDU) including
a reordering PDU.
13. The WTRU of claim 11, wherein the WTRU is in one of a Cell_FACH
state, a Cell_PCH state, or a URA_PCH state.
14. The WTRU of claim 12, wherein the WTRU includes a single hybrid
automatic repeat request (HARQ) process for receiving the MAC-ehs
PDU.
15. The WTRU of claim 14, wherein each MAC-ehs PDU is transmitted
more than once and each MAC-ehs PDU retransmission is completed
before starting transmission of a subsequent MAC-ehs PDU.
16. The WTRU of claim 11, wherein the condition has been met if the
data is from a certain priority queue.
17. The WTRU of claim 12, wherein the condition has been met if the
received MAC-ehs PDU is associated with a common HS-DSCH radio
network temporary identity (H-RNTI).
18. The WTRU of claim 11, wherein the condition has been met if the
data is from a certain logical channel.
19. The WTRU of claim 18, wherein the certain logical channel is
one of a broadcast control channel (BCCH) or a paging control
channel (PCCH).
20. The WTRU of claim 12, wherein the received MAC-ehs PDU is
received while the (WTRU) is in one of a Cell_FACH state, Cell_PCH
state, or URA_PCH state, and further comprising setting an initial
value of a next_expected_TSN to a lower edge of a receive window
(RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1).
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/048,855 filed Mar. 14, 2008, which claims
the benefit of U.S. provisional application No. 60/895,028 filed
Mar. 15, 2007, 60/895,835 filed Mar. 20, 2007, 60/915,023 filed
Apr. 30, 2007, 60/916,993 filed May 9, 2007, 60/940,209 filed May
25, 2007, and 60/941,465 filed Jun. 1, 2007, which are incorporated
by reference as if fully set forth.
FIELD OF INVENTION
[0002] The present invention is related to wireless
communications.
BACKGROUND
[0003] Evolved high speed packet access (HSPA) systems are
currently being developed within the framework of the Third
Generation Partnership Project (3GPP) Release 7. One feature of the
3GPP Release 7 is the possibility for a user equipment (UE) to
receive user and/or control data via a high-speed downlink shared
channel (HS-DSCH) not only in a Cell_DCH state but also in
Cell_FACH, URA_PCH, Cell_PCH states.
[0004] In the high speed downlink packet access (HSDPA), a UE
receives a packet, (i.e., MAC-hs protocol data unit (PDU) or
MAC-ehs PDU), from a Node-B implementing a hybrid automatic repeat
request (HARQ) technique. In the Cell_DCH state, the UE sends a
positive acknowledgment (ACK) or a negative acknowledgment (NACK)
to the Node-B after each HARQ transmission to indicate whether the
UE received the packet successfully or not.
[0005] Because of the delay required by the UE to decode and then
transmit this feedback, the Node-B transmits (or re-transmits)
different packets after sending the packet but before receiving the
corresponding feedback for continuous transmission of packets.
Since the number of transmissions required for successful decoding
at the UE varies from packet to packet, there is a possibility that
the HARQ entity in the UE does not deliver packets in the same
order as their respective initial transmissions from the Node-B. To
alleviate this issue, the medium access control (MAC) layer in the
UE performs reordering prior to delivery of the received packets to
higher layers. The reordering is based on a transmission sequence
number (TSN) in the MAC-hs header.
[0006] While in the Cell_DCH state, a UE determines whether an
HS-DSCH transmission from the Node-B is destined to the UE by
masking the cyclic redundancy check (CRC) of the high-speed shared
control channel (HS-SCCH) with its unique, (i.e., UE-specific),
HS-DSCH radio network temporary identifier (H-RNTI). However, while
in the Cell_PCH, URA_PCH. or Cell_FACH states, the UE does not
necessarily have a UE-specific H-RNTI. For instance, upon cell
reselection, the UE does not necessarily know its UE-specific
H-RNTI to use in the target cell when the UE receives a cell update
confirm message. To resolve this problem, the network may use a
common H-RNTI that all WTRUs may decode and use in-band signaling
to identify the UE. In addition, a common H-RNTI may be needed to
allow the network to broadcast messages, (e.g., broadcast control
channel (BCCH) messages), to all WTRUs camping on a given cell.
[0007] Some problems arise when attempting to implement the
reordering functionality with UE(s) receiving data via the HS-DSCH
utilizing a common H-RNTI. A first problem is that a UE potentially
delays delivery of data to higher layers because the reordering
function waits for the arrival of packets that are not even
destined to the UE.
[0008] Another problem occurs when the UE performs MAC-hs or
MAC-ehs reset, (e.g., upon cell resection). After performing cell
reselection, a UE initializes some variables related to reordering,
(e.g., next_expected_TSN and RcvWindow_UpperEdge), during the
MAC-ehs reset. When utilizing a common H-RNTI, however, the target
cell cannot re-initialize the TSN value without affecting all other
WTRUs already utilizing this common H-RNTI in that target cell.
Therefore, the UE joining the target cell cannot rely on the
re-initialization of the TSN to perform subsequent reordering. As a
result, undesirable effects may occur. For instance, if the
sequence number (SN) of the first received packet after the MAC-ehs
reset happens to be within the initial receive window and below the
initial value of next_expected_TSN, this packet will be
discarded.
[0009] Prior art could result in excessive delays upon performing
the cell update procedure when utilizing the HS-DSCH in a Cell_FACH
state. Node-B transmissions over the high-speed channel that are
made without knowledge of the UE identity, (i.e., using a common
H-RNTI), present a difficulty for the support of reordering. The
Node-B cannot use UE-specific TSNs since the identity of the
intended receiver is not known at the MAC-ehs entity of the UE.
Thus, a UE starting to listen to such transmissions has no
knowledge of the next TSN to expect for in-sequence delivery.
SUMMARY
[0010] Method and apparatus for receiving HS-DSCH transmissions are
disclosed. A MAC-ehs entity in a wireless transmit/receive unit
(WTRU) receives MAC-ehs PDUs via an HS-DSCH while in one of
Cell_FACH, Cell_PCH, and URA_PCH states. The reordering PDUs
included in the MAC-ehs PDUs may be sent to a next processing
entity without performing reordering of the reordering PDUs.
[0011] A single hybrid automatic repeat request (HARQ) process may
be used for receiving the MAC-ehs PDUs, and all retransmissions of
a MAC-ehs PDU may be completed before starting transmission of a
subsequent MAC-ehs PDU. Alternatively, no HARQ retransmissions may
be performed for the MAC-ehs PDUs and all MAC-ehs PDUs may be
transmitted only once. Alternatively, an HARQ entity may hold a
received MAC-ehs PDU and deliver the received MAC-ehs PDU only
after completion of last HARQ transmissions of the received MAC-ehs
PDU. Alternatively, an HARQ entity may deliver a successfully
decoded MAC-ehs PDU immediately to the next processing entity and
send an indication when last HARQ transmission for the successfully
decoded MAC-ehs PDU occurs. A duplicate avoidance and reordering
(DAR) function may be applied at a radio link control (RLC) layer
to all logical channels or acknowledged mode (AM) data.
[0012] A certain reordering queue may enter a suspend state upon
occurrence of a triggering event and MAC-ehs PDUs distributed to
the reordering queue in the suspend state may be forwarded to the
next processing entity without performing reordering of the
reordering PDUs. MAC-ehs reset procedure may be extended for a
certain transmission such that the MAC-ehs reset is performed after
receiving a MAC-ehs PDU in a target cell. When performing a MAC-ehs
reset, variables next_expected_TSN and RcvWindow_UpperEdge is set
to a value "Pending".
[0013] A transmission sequence number (TSN) to be used in a cell
for sending a MAC-ehs PDU using a common HS-DSCH radio network
temporary identity (H-RNTI) may be provided to a WTRU and the
MAC-ehs entity may be configured with the TSN. A radio resource
control (RRC) message transmitted via an HS-DSCH using a common
HS-DSCH radio network temporary identity (H-RNTI) may be controlled
to be small enough to fit into a single MAC-ehs PDU.
[0014] In a reordering pending state, reordering variables may be
sent based on a TSN of the first MAC-ehs PDU. The received MAC-ehs
PDUs may be stored in a reordering buffer and delivered to a higher
entity based on HARQ information. When TSN numbers are restricted,
a modulo x may be used for all arithmetic operation of a reordering
entity, where x is a lowest TSN number restricted. The TSN may be
assigned to each WTRU independently.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] A more detailed understanding may be had from the following
description, given by way of example in conjunction with the
accompanying drawings wherein:
[0016] FIG. 1 is a block diagram of an example WTRU;
[0017] FIG. 2 is a block diagram of a MAC-ehs entity;
[0018] FIG. 3 is a block diagram of a WTRU MAC-ehs entity with no
reordering for data received from certain priority queues; and
[0019] FIG. 4 is a block diagram of a WTRU MAC-ehs entity with no
reordering and no reassembly for data received from certain
priority queues.
DETAILED DESCRIPTION
[0020] When referred to hereafter, the terminology "wireless
transmit/receive unit (WTRU)" includes but is not limited to a user
equipment, 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
"Node-B" includes but is not limited to a base station, a site
controller, an access point (AP), or any other type of interfacing
device capable of operating in a wireless environment. Hereinafter,
embodiments will be explained with reference to Cell_FACH state as
an example. It should be noted that embodiments are applicable to
Cell_PCH or URA_PCH states.
[0021] FIG. 1 is a block diagram of an example WTRU 100. The WTRU
100 includes a physical layer 110, a medium access control (MAC)
layer 120, a radio link control (RLC) layer 130, a radio resource
control (RRC) layer 140, a higher layer(s) 150, and the like. The
MAC layer 120 includes a MAC-ehs entity. It should be noted that
the MAC-ehs entity may be called as a MAC-hs entity or any other
name. Hereinafter, only the terminology "MAC-ehs" will be used.
[0022] FIG. 2 is a block diagram of a MAC-ehs entity 200. The
MAC-ehs entity 200 includes a hybrid automatic repeat request
(HARQ) entity 202, a disassembly entity 204, a reordering queue
distribution entity 206, a plurality of reordering queues 208,
demultiplexing entities 210, and reassembly entities 212. The
received MAC-ehs PDU via the HARQ entity 202 is disassembled into
reordering PDUs by the disassembly entity 204. The reordering PDUs
are distributed to a reordering queue 208 by the reordering queue
distribution entity 206 based on the received logical channel
identifier. The reordering PDUs are reorganized according to the
transmission sequence number (TSN). Reordering PDUs with
consecutive TSNs are delivered to a higher layer upon reception. A
timer mechanism determines delivery of non-consecutive data blocks
to higher layers. There is one reordering entity 208 for each
priority queue. The demultiplexing entity 200 routes the reordered
reordering PDUs to a reassembly entity 202 based on the logical
channel identifier. The reassembly entity 202 reassembles segmented
MAC-ehs SDUs to original MAC-ehs SDUs and forwards the MAC-ehs SDUs
to upper layers.
[0023] In accordance with a first embodiment, MAC-ehs PDUs are
delivered in-sequence from the HARQ entity and a MAC-ehs layer may
be relieved from its reordering duty by ensuring that packets are
always received in order at the WTRU. If the MAC-ehs layer does not
have to perform reordering, the MAC-ehs reset functionality may be
simplified when the WTRU is not assigned a WTRU-specific H-RNTI.
Four options for implementing the first embodiment are disclosed
below.
[0024] With a first option for the first embodiment, a single HARQ
process is used for certain transmissions. The transmissions may be
from a certain priority queue, from a certain logical channel, or
for which the identity of the destined WTRU is not known at the
MAC-ehs entity, (i.e., when MAC-ehs PDUs are sent using a common
H-RNTI). In the Cell_FACH state, the MAC-ehs entity in the Node-B
transmits MAC-ehs PDUs repeatedly for a preconfigured number of
times without receiving feedback from the WTRU, which is called a
repetitive HARQ transmission scheme. The Node-B completes all
retransmissions of a MAC-ehs PDU before starting transmission of a
subsequent MAC-ehs PDU for the certain transmissions for which
in-order delivery is essential.
[0025] With the first option, a large delay imposed by the minimum
interval between successive HARQ transmissions on the same HARQ
process that is defined in the current 3GPP specifications may be
an issue. Under the current 3GPP specifications, a WTRU may discard
any MAC-ehs PDU intended for a HARQ process if it is received
within five (5) sub-frames from the last reception of data intended
for the same HARQ process. Such a restriction is justifiable when
utilizing the HS-DSCH in a Cell_DCH state since a certain minimum
round-trip time is imposed by the HARQ feedback from the WTRU.
However, when utilizing the HS-DSCH in a Cell_FACH state, a WTRU is
not sending ACK/NACK feedback to the Node-B and thus a shorter
interval is feasible.
[0026] The delay problem may be resolved by configuring the MAC-ehs
entity differently while the WTRU is in a Cell_FACH state. For
example, in the Cell_FACH state, the MAC-ehs entity of the WTRU may
be configured not to discard packets received within five
sub-frames from the last reception of a packet intended for the
same HARQ process, and may do so only in the Cell-DCH state.
[0027] Alternatively, in the Cell_FACH state, the WTRU MAC-ehs
entity may be configured to discard a packet intended for an HARQ
process if it is received within r sub-frames from the last
reception of a packet intended for the same HARQ process. The
number n may be fixed and pre-defined in the specifications. If
n=0, it is understood that the minimum is not specified when the
WTRU is in the Cell_FACH state. The number n may be WTRU-dependent.
The minimum number of sub-frames n may be signaled by higher layers
as a capability of the WTRU. For instance, the WTRU may signal in
advance its capability information (as part of any information
element of the higher layer protocol) to the radio network
controller (RNC). The RNC may signal the minimum number of
sub-frames n applicable to certain data. Alternatively, the RNC may
signal to the Node-B the minimum number n to use for each logical
channel, for each priority queue, or for each H-RNTI.
[0028] The above two alternatives may be combined so that a fixed
and pre-defined minimum number of sub-frames m that is applicable
to any WTRU utilizing the HS_DSCH in the Cell_FACH state may be
provided along with a smaller WTRU-dependent value n (<m) by
higher layers as a capability of the WTRU. This is useful for
transmitting on certain logical channels that are not dedicated to
a specific WTRU, such as common control channel (CCCH) or BCCH. In
this case the Node-B may use a minimum of m for logical channels
that are not dedicated to a specific WTRU and use a smaller
WTRU-dependent minimum for data destined to a specific WTRU.
[0029] When a single HARQ process is used with the common H-RNTI
only, the HS-SCCH format may be changed so that the conventional
3-bit "Hybrid-ARQ process information" field may be removed. This
results in lesser number of information bits to encode in the
HS-SCCH and would result in lower transmission power requirement.
WTRUs may determine which scheme has been applied by relying on
whether the transmission was masked by the common H-RNTI or
not.
[0030] The Node-B may be informed to use a single HARQ process
explicitly, using one of the conventional Node-B application part
(NBAP) messages used for configuration or reconfiguration of
HS-DSCH resources. A new information element (IE) may be added
indicating the number of HARQ processes to be used by the MAC-ehs
entity.
[0031] Alternatively, a conventional IE in the NBAP messages used
for configuration of HS-DSCH resources may be extended for this
purpose. For example, the HARQ memory allocation IE may be extended
to include a new field indicating the number of HARQ process to be
used or setting a bit string for all HARQ process to indicate which
HARQ process can be used for a certain logical channel or a certain
common H-RNTI.
[0032] Alternatively, the Node-B may be informed implicitly by
means of another IE. For example, when the timer T1 is set to zero
(0), it may implicitly mean that only one HARQ process is being
used. Alternatively, a new IE that indicates no reordering or no
segmentation may be used to implicitly signal single HARQ
process.
[0033] Alternatively, the MAC-ehs entity in the Node-B may be
instructed not to include a TSN, or include a TSN but not to
increment the TSN, and this may implicitly indicate that a single
HARQ process is used, or vice versa.
[0034] Alternatively, the Node-B may be informed over the Iub frame
protocol. A new field may be added to the Iub frame protocol that
indicates whether a particular message should be sent using a
single HARQ process or multiple HARQ processes.
[0035] Any combination of the alternatives disclosed above may be
used.
[0036] With a second option for the first embodiment, no HARQ
retransmissions are performed for certain transmissions. The Node-B
does not send any HARQ retransmissions for PDUs from a certain
priority queue, from a certain logical channel, or for which the
identity of the destined WTRU is not known at the MAC-ehs entity,
(i.e., common H-RNTI is used), and the MAC-ehs PDUs for those data
are transmitted only once over the air. The MAC-ehs PDUs will be
received in order and the WTRU does not need to perform any
reordering for the particular transmission. The MAC-ehs entity in
the WTRU forwards successfully decoded PDUs directly to a higher
entity, bypassing the reordering function altogether.
[0037] The WTRU may be informed that a single HARQ transmission
takes place per PDU explicitly in the L3 configuration information,
(e.g., BCCH/BCH), for a particular priority queue or logical
channel or for particular transmissions. Alternatively, a new L1
signaling, (e.g., a new field in the HS-SCCH), may be used to
indicate that no HARQ retransmissions will take place.
Alternatively, fields in the HS-SCCH may be modified to indicate
that no HARQ retransmission will take place for a particular
packet. Alternatively, a new field may be added in the MAC-ehs
header to indicate a single HARQ transmission of the packet.
[0038] With a third option for the first embodiment, a repetitive
HARQ transmission scheme is used and delivery of a decoded packet
is delayed at the HARQ entity of the WTRU. With this option, the
Node-B may use more than a single HARQ process, (e.g., to provide
better time diversity). However, a constraint is imposed such that
the last. HARQ transmissions of successive MAC-ehs PDUs are
transmitted in order at the Node-B. In other words, the last HARQ
transmission for MAC-ehs PDU #n-1 is always transmitted before the
last HARQ transmission for MAC-ehs PDU #n. Such a constraint can be
satisfied, for instance (but not limited to) when HARQ
retransmissions occur at fixed interval (synchronous HARQ).
[0039] The HARQ entity at the WTRU does not deliver a successfully
decoded packet until all transmissions. (i.e., the preconfigured
number of repetitions), for this packet have been sent. In order to
determine whether all transmissions for a packet has been made, the
WTRU HARQ entity may wait for the reception of HS-SCCH transmission
with a new data indicator (NDI) flag indicating a new PDU to
deliver the decoded packet. Alternatively, the WTRU may count the
number of transmissions, (e.g., based on the HS-SCCH
transmissions), for MAC-ehs PDUs and deliver the successfully
decoded MAC-ehs PDU only after the preconfigured maximum number of
transmissions is reached with respect to this MAC-ehs PDU. The
maximum number is signaled to the WTRU through higher layers.
[0040] With a fourth option for the first embodiment, the HARQ
entity at the WTRU delivers successfully decoded packets
immediately to the above entities, (i.e., reordering entity), in
the MAC-ehs entity, and the reordering entity retains the delivered
MAC-ehs PDU until it receives the indication from the HARQ entity
that the last HARQ transmission has taken place. After receiving
the indication, the reordering entity sends the MAC-ehs PDU to an
above entities/sub-layers. The HARQ entity can make this
determination based on one of the methods described in the third
option.
[0041] With this option, the reordering entity does not need to use
the TSN field of the MAC-ehs PDU (if present) to determine when to
send the PDU to upper entities, but may still use a release timer
(such as T1) to deliver a MAC-ehs PDU for which no indication has
been received from the HARQ entity. Certain reordering queues may
rely on the indication provided by the HARQ entity to determine
when to deliver the PDUs to upper entities, while other reordering
queues may use the conventional reordering mechanism.
[0042] In accordance with a second embodiment, MAC functionalities,
(i.e., MAC-ehs functionalities), may be simplified for certain
priority queues to avoid issues associated with reordering in the
Cell-FACH state. The MAC functionality simplification may be
implemented in conjunction with the first embodiment, and this
would minimize (or eliminate) out-of-order delivery of MAC-ehs PDUs
to higher layers.
[0043] With a first option for the second embodiment, reordering is
avoided for data transmitted from certain priority queues. The
MAC-ehs functionality at the WTRU is modified so that data received
from certain priority queues is directly sent to a reassembly
entity without performing reordering. The reassembly entity
reassembles a MAC-ehs service data unit (SDU) from segments of the
MAC-ehs SDU.
[0044] FIG. 3 shows a MAC-ehs entity 300 in accordance with this
option. It should be noted that the exact order of demultiplexing
and reassembly functions may be different from FIG. 3. MAC-ehs PDUs
received via the HARQ entity 302 are forwarded to a disassembly
entity 304. The disassembly entity 304 disassembles the MAC-ehs
PDUs into reordering PDUs. The reordering PDUs may be placed in a
reordering queue 308 via the reordering queue distribution entity
306. In accordance with this option, for certain priority queues,
the reordering is avoided and the reordering PDUs are directly
forwarded to the demultiplexing entity 310a. The demultiplexing
entity 310a routes the reordering PDUs to a correct reassembly
entity 312a based on the logical channel identity. The reassembly
entity 312a reassembles segmented MAC-ehs SDUs to a complete
MAC-ehs SDU.
[0045] Different criteria may be used to determine whether the data
should be distributed to a reordering entity for reordering or to a
reassembly entity without reordering. If the identity of the WTRU
that the data within the MAC-ehs PDU is destined to is not known to
the MAC-ehs entity, (i.e., when the MAC-ehs PDUs are transmitted
using a common H-RNTI), the MAC-ehs PDU may be sent to the
reassembly entity without performing reordering. The MAC-ehs entity
knows the identity of the WTRU if the MAC-ehs PDU has been received
using a dedicated H-RNTI or if a WTRU identity is contained within
the MAC-ehs PDU. The Node-B may always use a common H-RNTI for any
data from a priority queue that does not support reordering.
[0046] Whether the data should be distributed to a reordering
entity for reordering or to a reassembly entity without reordering
may depend on a logical channel identity of the received data,
regardless of whether the data is received using a common H-RNTI or
a dedicated H-RNTI. This allows multiplexing data from priority
queues that support reordering with data from priority queues that
do not support reordering. This also allows not utilizing the
reordering functionality even when a dedicated H-RNTI is used.
[0047] The logical channels that support reordering may be
pre-determined based on the type of logical channel, (e.g., CCCH,
BCCH, paging control channel (PCCH), DCCH, and the like), and/or a
logical channel identity.
[0048] Alternatively, the WTRU may be informed by higher layers,
(e.g., radio resource control (RRC) signaling), of which logical
channels support reordering. For example, the "RB mapping info" IE
contains information on the downlink radio link control (RLC)
logical channel(s). An IE may be added to indicate whether
reordering is performed at the MAC-ehs for each logical channel.
Alternatively, in the "RB mapping info" IE, the "Reordering queue
ID" IE that may be added to support the L2 enhancements may take a
special value indicating a queue that does not support reordering.
Alternatively, the IE indicating the parameters of the queue,
(e.g., "Added or reconfigured MAC-d flow", common MAC flow
broadcasted in system information, or the like), may be modified or
extended to indicate whether the queue supports reordering or not.
Such indication may be given by adding a new IE indicating if
reordering is supported, or alternatively some of the conventional
IEs may take a new possible value that would indicate that
reordering is not supported. For instance, the "T1" IE may take as
one of its possible values, (e.g., "0"), indicating that reordering
is not supported on this queue. The "MAC-hs window size" IE may
also take as one of its possible values, (e.g., "0"), indicating
the same.
[0049] Alternatively, other indication in the MAC-ehs PDU header
may be used to indicate which logical channel(s) supports
reordering and which logical channel(s) does not. For example, a
special field indicating whether reordering is to be applied or not
may be included. Another example is utilization of a special value
for the TSN field, (e.g., "111111").
[0050] Any combination of the above alternatives may be used to
indicate which logical channel(s) supports reordering and which
logical channel(s) does not. For example, the logical channel
identity combined with the WTRU ID may be used to indicate whether
the MAC-ehs PDU should be sent to the reordering queue for
reordering or the reassembly entity without performing reordering.
Signaling radio bearer #1 (SRB#1) messages will be sent on a DCCH
using a common H-RNTI, but other messages may be sent on a DCCH
using a dedicated H-RNTI. DCCH messages with a common H-RNTI may be
sent to the reassembly entity without performing reordering, while
DCCH messages with a dedicated H-RNTI may be sent to the reordering
queues for reordering.
[0051] Although re-ordering is not performed, the TSN field may
still be used by the MAC-ehs entity in the Node-B when building the
MAC-ehs PDU, and the TSN field may be used to facilitate the
reassembly operation at the WTRU. For example, the reassembly
entity may delete any segment present in the reassembly buffer if
non-consecutive TSNs are received.
[0052] Alternatively, the TSN may be removed from the MAC-ehs
header. In this case, the WTRU may still use the segmentation
indication to reassemble packets, even though there is a
possibility of bad reassembly if a PDU is missing. In case the TSN
field is not used, the WTRU would know whether to expect a TSN
field in the MAC-ehs header for a logical channel based on the
knowledge of the mapping between this logical channel and a queue
that does not support reordering.
[0053] A process for reassembling segmented MAC-ehs SDUs in case
that the TSN field is kept in the MAC-ehs header, but reordering is
not performed is explained hereinafter. After receiving a MAC-ehs
PDU, a WTRU determines whether the payload of the MAC-ehs PDU is a
full MAC-hs SDU, or a segment, and if it is a segment, whether it
is a first segment, a middle segment, or a last segment. If the
payload is a full MAC-ehs SDU, the MAC-ehs SDU is forwarded to a
higher layer or to an entity following the reassembly entity.
[0054] If the payload is the first segment of a MAC-ehs SDU, and if
the WTRU has a stored middle segment(s) with a consecutive sequence
number higher than the received PDU, the first segment is combined
with the consecutive segments. If the WTRU has stored a last
segment with a consecutive sequence number higher than the received
PDU, they are combined and the full MAC-ehs SDU is delivered to an
upper layer. Otherwise, the payload is stored in the reassembly
entity.
[0055] If the payload is a last segment of a MAC-ehs SDU, and if
the reassembly entity has stored consecutive segment with a TSN
lower than the received packet, they are combined. If a full
MAC-ehs SDU is formed, it is delivered to an upper layer.
Otherwise, the last segment is stored in the reassembly buffer.
[0056] If the payload is a middle segment of a MAC-ehs SDU, and if
the reassembly entity has stored consecutive segments with TSNs
higher or lower than the received packet, they are combined. If a
full SDU is created, it is forwarded to a higher layer. Otherwise,
it is stored in the reassembly buffer.
[0057] To discard segments from the reassembly entity, a
timer-based discard mechanism may be used. Optionally, the packet
may be discarded if the buffer is full or the maximum amount of
segments allowed to be stored is reached. Segments with the oldest
TSN numbers may be discarded. In addition, the conventional
re-ordering parameters RcvWindow_UpperEdge, next_expected_TSN,
T1_TSN, and TSN_Flush are not required to be maintained and
processed.
[0058] The timer-based discard mechanism may be implemented in one
or a combination of the following ways. Every segment is maintained
in the reassembly buffer for a configured period of time, (i.e.,
every time a segment corresponding to a MAC-ehs SDU is received, a
timer for that segment is started). When the timer expires, all
segments corresponding to that MAC-ehs SDU are discarded. The timer
starts only when a segment corresponding to a reordering PDU with a
TSN greater than the next expected TSN is received. A variable
Tseg_TSN is set to this TSN. When the timer expires the following
actions may be performed.
[0059] a. If segment indicator (SI) of Tseg_TSN is "01", [0060] i.
Discard all payload units with TSN.ltoreq.Tseg_TSN; and [0061] ii.
Set next_expected_TSN to the next not received segment TSN.
[0062] b. If SI of T1_TSN is "10", [0063] i. Discard all payload
units with TSN<Tseg_TSN; and [0064] ii. Set next_expected_TSN to
the next not received segment TSN.
[0065] c. If SI of Tseg_TSN is "11", [0066] i. Discard the first
payload unit corresponding to that TSN and all payload units with
TSN<T1_TSN. This step must ensure that the last payload unit
corresponding to that TSN is not discarded, since that payload unit
corresponds to the first payload unit.
[0067] With a second option for the second embodiment,
segmentation, reordering and reassembly are avoided for data
transmitted from certain priority queues. Any data transmitted from
certain priority queues does not undergo segmentation, reassembly,
or reordering. FIG. 4 shows the MAC-ehs entity in the WTRU in
accordance with this option. As in the first option for the second
embodiment, different criteria may be used to determine whether the
data should be distributed to a reordering queue for reordering or
not.
[0068] With this option, it is not required to add TSN and SI
fields to the MAC-ehs PDUs for the corresponding queues.
Alternatively, the TSN and SI fields may be added, but the SI field
may always be set to a certain value, (e.g., "00"), and the TSN may
be set to a constant value, or optionally incremented but not used
for any reordering or reassembly purposes. Furthermore, when
setting up the queues at the WTRU, there is no need to maintain and
process the following variables: TSN number, RcvWindow_UpperEdge,
next_expected_TSN, T1_TSN, and TSN_Flush.
[0069] When receiving a MAC-ehs PDU, the WTRU knows that the TSN
and SI fields are not present for a certain logical channel based
on either the knowledge of the mapping of this logical channel to a
given queue that does not support reordering and
segmentation/reassembly, or based on the use of a common H-RNTI
when transporting this channel. In such case, MAC-ehs SDUs are
immediately disassembled and de-multiplexed according to logical
channel and sent to a higher layer.
[0070] With respect to the second embodiment, a MAC-ehs reset
procedure may be modified. In accordance with a conventional
MAC-ehs reset procedure, if a MAC-ehs reset is requested by an
upper layer, the WTRU shall, at the activation time indicated by
higher layers;
[0071] a) flush soft buffer for all configured HARQ processes;
[0072] b) stop all active re-ordering release timer (T1) and set
all timer T1 to their initial value;
[0073] c) start TSN with value `0` for the next transmission on
every configured HARQ process;
[0074] d) initialize the variables RcvWindow_UpperEdge and
next_expected_TSN to their initial values;
[0075] e) disassemble all MAC-ehs PDUs in the re-ordering buffer
and deliver all MAC-d PDUs to the MAC-d entity;
[0076] f) flush the re-ordering buffer; and
[0077] g) if the MAC-ehs reset was initiated due to reception of
the IE "MAC-hs reset indicator" by the upper layers, indicate to
all acknowledged mode (AM) RLC entities mapped on an HS-DSCH to
generate a status report.
[0078] If the first option of the second embodiment is implemented,
this procedure is modified so that step (d) is only performed for
the queues that support reordering. If the first option is
implemented with reassembly functionality, the reset procedure
should ensure that the reassembly buffer is flushed after the last
MAC-ehs PDU has been processed.
[0079] If the second option of the second embodiment is
implemented, this procedure should be modified so that steps
(b)-(f) are only executed for the queues that support reordering.
In addition, segments in the reassembly buffer that cannot be
successfully reassembled should be discarded.
[0080] It should be noted that some of these steps may have to be
modified to support other upcoming features of HSPA evolved, such
as L2 improvements.
[0081] The simplifications to the MAC-ehs entity functionality
described above may result in out-of-order delivery of MAC SDUs to
the RLC entity. This may cause difficulties particularly when the
MAC-ehs SDUs carry RRC signaling. These difficulties may be avoided
if the RLC entity performs reordering. Conventionally, a duplicate
avoidance and reordering (DAR) function is defined for an
unacknowledged mode (UM) of the RLC. However, the DAR function is
currently only applicable to a multimedia broadcastimulticast
service (MBMS) traffic channel (MTCH).
[0082] In accordance with a third embodiment, the DAR function is
applied to other logical channels than MTCH, such as DCCH or DTCH.
Such extension of RLC UM DAR functionality would be especially
useful for the case of signaling radio bearer (SRB) #1 which is
defined with RLC UM.
[0083] Several methods are possible to enable the use of DAR
functionality to the other logical channels. The WTRU may be
informed of the parameters to use for the DAR function by higher
layers, or the parameters may be pre-determined. For instance, RRC
signaling may be modified so that the "DL Duplication Avoidance and
Reordering Info" may optionally be present not only within the "RLC
info MBMS" IE but also within the "RLC info" IE, if the UM RLC mode
is selected. The parameter values for the default radio
configurations may also be updated with the new parameter for SRB1
and other RBs.
[0084] Similarly, DAR or a similar function may be introduced in
the RLC acknowledge mode (AM) of operation, where it may be
configured that the AM RLC delivers SDUs in-sequence to higher
layers. The conventional AM RLC does not perform any reordering on
the receive side.
[0085] The reordering functionality may be modified to prevent
excessive delays during the cell update procedure when HS-DSCH is
utilized in the Cell_FACH state. This scheme may be used if it is
desired to keep the reordering functionality for a certain priority
queue. This scheme does not assume any modification to the HARQ
entity behavior, but would be effective regardless of whether such
modifications are implemented or not.
[0086] It should be noted that the embodiments described below are
not only applicable to the cell update procedure (cell
reselection), but also applicable to initial configuration and
setup of the MAC-ehs entity when entering the enhanced CELL_FACH
state or initiating HS-DSCH reception in the CELL_FACH. CELL_PCH or
URA_PCH states.
[0087] In accordance with a fourth embodiment, a reordering queue
may enter the suspend reordering state when a certain triggering
event occurs. While in the normal state, the conventional
reordering procedures are performed. While a reordering queue is in
the suspend reordering state, received data going into the suspend
state reordering queue is directly transferred to the next
processing entity, (e.g., a reassembly entity, a disassembly
entity, a demultiplexing entity depending on the MAC-ehs
architecture, or a layer above the MAC-ehs entity), without
consideration for the TSN associated with the data.
[0088] The triggering events to get into the suspend reordering
state may be, for instance, execution of a MAC-ehs reset procedure,
(possibly following a command from an RRC entity), or an explicit
command from the RRC entity to go into the suspend reordering
state. The RRC entity may issue this command, for instance, upon
initiating a cell update procedure with a cause of cell
reselection. If an explicit command is issued, the RRC entity may
optionally decide to flush the reordering buffer.
[0089] The reordering queue(s) that is subject to suspension of
reordering may be signaled by higher layers along with (or as part
of) the RRC command, if applicable. The higher layer signaling may
be performed using one of the options listed above. Alternatively,
it may be pre-signaled upon setting up the logical channel mapped
to the queue, or it may be pre-defined depending on the type of
logical channel mapped to the queue, (e.g., it may be pre-defined
such that any queue mapped onto a CCCH logical channel undergoes
suspension of reordering upon MAC-ehs reset).
[0090] The reordering queue returns to the normal state when a
certain transition event occurs. The transition events may be, for
example, reception of a packet for the logical channel mapped to
the queue after entering into the suspend state. After receiving
the packet, the WTRU performs the following actions:
[0091] (a) Set next_expected_TSN=TSN-x, where, for example,
-1.ltoreq.x<6 (the value of x>0 is to ensure that if a first
packet is received out of order, it will not discard the next
packets with lower TSNs) and the TSN is the transmission sequence
number of the received packet, and the value of x may be
pre-determined or pre-signaled by higher layers;
[0092] (b) If x is not equal zero or -1, set T1_TSN=TSN of this
packet and start the T1 timer;
[0093] (c) Set RcvWindow_UpperEdge=TSN+y, where y may be
pre-determined or pre-signaled by higher layers; and
[0094] (d) Return to normal reordering state.
[0095] It should be noted that for the above event, a definition of
a new state is not formally needed since the WTRU does not receive
any data for the concerned queue while in the suspended reordering
state. It would be equivalent to say that the MAC-ehs reset
procedure for the concerned queues is completed only after
reception of data for these queues.
[0096] The transition event may be an explicit command from the RRC
entity to return to the normal reordering state. In this case, the
RRC entity notifies the MAC-ehs entity when the MAC-ehs entity
should return to the normal reordering state. Such command may
itself be triggered by the RRC entity receiving a cell update
confirm message from its peer entity, or any other event related to
RRC procedures. Prior to receiving the command to return to the
normal reordering state, (i.e., while in the suspend reordering
state), the WTRU has to maintain the next_expected_TSN, and
RcvWindow_UpperEdge variables for each concerned queue in the
following manner:
[0097] (a) At the first time a packet is received for the queue
after the MAC-ehs reset: [0098] (i) Set next_expected_TSN to TSN+1
of this packet. [0099] (ii) Set RcvWindow_UpperEdge to TSN+y, where
y may be pre-determined or pre-signaled by higher layers. [0100]
(iii) Optionally, the variable "TSN_init" may be set to the TSN of
the received packet.
[0101] (b) For subsequent packets for the same queue with
transmission sequence number=TSN: [0102] (i) Set next_expected_TSN
to TSN+1 if TSN.gtoreq.next_expected_TSN. [0103] (ii) Set
RcvWindow_UpperEdge to TSN+y if TSN+y>RcvWindow_UpperEdge, where
y may be pre-determined or pre-signaled by higher layers.
[0104] The transition event to return to the normal state may be
expiration of a timer (T_init) started upon transition to the
pending state. This timer may be the same as the conventional T1
timer. If it is not the same, the value of the T_init timer may be
either specified by higher layers, (e.g., using the same RRC
signaling messages that contain the value of the T1 timer, with an
additional information element for the value of this new T_init
timer), or pre-defined. This value may be lower than or equal to
the T1 timer to avoid excessive delays.
[0105] When a triggering event to the suspend reordering state
occurs, (e.g., when a MAC-ehs reset occurs), the reordering queue
enters and stays in the suspend reordering state for the duration
of the T_init timer (plus possibly the period of time between the
MAC-ehs reset and the reception of the first correct MAC-ehs PDU,
if it is elected to start the T_init timer upon reception of this
PDU). Optionally, the values of "next_expected_TSN" and
"RcvWindow_UpperEdge" may be set to a special value ("pending")
upon execution of the MAC_ehs reset instead of being set to their
initial values as in the conventional procedure, which will be
explained in detail below.
[0106] Alternatively, the transition event may be successful
reception of N number of PDUs with consecutive TSNs, or N out of M
successful PDUs within M consecutive TSNs.
[0107] It should be noted that in the event MAC-ehs reset is
performed after a cell update confirm is received by higher layers,
the variables and contents of these queues should not be reset upon
MAC-ehs reset indication. In this case, if the queue is in the
suspend reordering state, the MAC-ehs reset will be an indication
that the cell update confirm has been received by higher layers,
and the queue can return to the normal state.
[0108] In accordance with a fifth embodiment, the MAC-ehs reset
procedure is modified so that for certain reordering queues, the
reset procedure is extended until the reception of data in the
target cell. The variables next_expected_TSN and
RcvWindow_UpperEdge are not reset to their initial values for the
concerned reordering queues immediately, but only upon reception of
data for these queues in the target cell.
[0109] If a reset of the MAC-ehs entity is requested by upper
layers, the WTRU shall at the activation time indicated by higher
layers:
[0110] (1) flush soft buffer for all configured HARQ processes;
[0111] (2) stop all active re-ordering release timer (T1) and set
all timer T1 to their initial value;
[0112] (3) disassemble all MAC-ehs PDUs in the re-ordering buffer
and deliver all MAC-d PDUs to the MAC-d entity (This step may be
modified due to unrelated changes to the MAC-ehs procedure in
future Releases);
[0113] (4) flush the re-ordering buffer; and
[0114] (5) if the MAC-hs reset was initiated due to reception of
the IE "MAC-hs reset indicator" by the upper layers, indicate to
all AM RLC entities mapped on HS-DSCH to generate a status
report.
[0115] For reordering queues for which the extended MAC-ehs
procedure applies:
[0116] (1) When data (reordering PDU) is received for this
reordering queue, set next_expected_TSN=TSN-x, where, for example,
0.ltoreq.x<6, and TSN is the transmission number of the received
reordering PDU, and the value of x may be pre-determined or
pre-signaled by higher layers;
[0117] (2) Optionally, if x is not equal to zero, set T1_TSN=TSN of
this packet and start T1 timer;
[0118] (3) Set RcvWindow_UpperEdge=TSN+y, where y may be
pre-determined or pre-signaled by higher layers; and
[0119] (4) End MAC-ehs reset procedure for the reordering
queue.
[0120] For all other reordering queues:
[0121] (1) start TSN with value 0 for the next transmission on
every configured HARQ process; and
[0122] (2) initialize the variables RcvWindow_UpperEdge and
next_expected_TSN to their initial values.
[0123] The queue(s) for which the extended MAC-ehs procedure
applies may be signaled by higher layers along with (or as part of)
the RRC command that triggers the MAC-ehs reset, if applicable.
Alternatively, it may be pre-signaled upon setting up the logical
channel mapped to the queue, or it may be pre-defined depending on
the type of logical channel mapped to the queue, (e.g., it may be
pre-defined that any queue mapped onto the CCCH logical channel
undergoes the extended MAC-ehs reset procedure). The signaling can
be performed using one of the options listed above.
[0124] In accordance with a sixth embodiment, additional special
values are defined for the reordering variables next_expected_TSN
and RcvWindow_UpperEdge. This special value may be labeled, for
instance, by one of the following: Pending, Undefined, or Waiting,
(the label "Pending" will be used hereafter).
[0125] For certain reordering queues, the MAC-ehs reset or new
MAC-ehs configuration procedure is modified so that the variables
"next_expected_TSN" and "RcvWindow_UpperEdge" are set to the value
"Pending" instead of being set to their initial values as specified
in the conventional procedure. Furthermore, the reordering
functionality is also modified so that when a MAC-ehs PDU with
TSN=SN is received, if the value of "next_expected_TSN" is set to
"Pending", the following actions are performed:
[0126] (1) The T1 timer is not started;
[0127] (2) Next_expected_TSN is set to TSN+1 (or alternatively,
TSN+x where x is pre-defined or set by higher layers, and); and
[0128] (3) RcvWindow_UpperEdge is set to TSN+y, where y may be
pre-determined or pre-signaled by higher layers.
[0129] The reordering queue(s) for which the modified MAC-ehs
procedure applies may be signaled by higher layers along with (or
as part of) the RRC command that triggers the MAC-ehs reset, if
applicable. Alternatively, it may be pre-signaled upon setting up
the logical channel mapped to the queue, or it may be pre-defined
depending on the type of logical channel mapped to the queue,
(e.g., it may be pre-defined that any queue mapped onto the CCCH
logical channel undergoes the extended MAC-ehs reset procedure).
The signaling can be performed using one of the options listed
above.
[0130] The modified reordering functionality for the receiver
operation is as follows:
[0131] When a MAC-hs PDU with TSN=SN is received:
[0132] If next_expected_TSN is NOT set to "Pending" [0133] if SN is
within the receiver window: [0134] if SN<next_expected_TSN, or
this MAC-hs PDU has previously been received: [0135] the MAC-hs PDU
shall be discarded; [0136] else: [0137] the MAC-hs PDU shall be
placed in the reordering buffer at the place indicated by the TSN.
[0138] if SN is outside the receiver window: [0139] the received
MAC-hs PDU shall be placed above the highest received TSN in the
reordering buffer, at the position indicated by SN; [0140]
RcvWindow_UpperEdge shall be set to SN thus advancing the receiver
window; [0141] any MAC-hs PDUs with TSN
RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE, i.e. outside the receiver
window after its position is updated, shall be removed from the
reordering buffer and be delivered to the disassembly entity;
[0142] if next_expected_TSN is below the updated receiver window:
[0143] next_expected_TSN shall be set to: [0144]
RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1; [0145] if the MAC-hs PDU
with TSN=next_expected_TSN is stored in the reordering buffer:
[0146] all received MAC-hs PDUs with consecutive TSNs from
next_expected_TSN (included) up to the first not received MAC-hs
PDU shall be delivered to the disassembly entity; [0147]
next_expected_TSN shall be advanced to the TSN of this first not
received MAC-hs PDU.
[0148] If a WTRU has insufficient memory to process a received
MAC-ehs PDU, the WTRU performs the following operations: [0149]
select TSN_flush such that: [0150]
next_expected_TSN<TSN_flush.ltoreq.RcvWindow_UpperEdge+1; [0151]
deliver all correctly received MAC-hs PDUs with TSN<TSN_flush to
the disassembly entity; [0152] if the MAC-hs PDU with TSN=TSN_flush
has previously been received: [0153] deliver all received MAC-hs
PDUs with consecutive TSNs from TSN_flush (included) up to the
first not received MAC-hs PDU to the disassembly entity; [0154]
advance next_expected_TSN to the TSN of this first not received
MAC-hs PDU. [0155] else: [0156] set next_expected_TSN to TSN_flush.
[0157] ENDIF [next_expected_TSN is NOT set to "Pending"] [0158]
Else (e.g. if next_expected_TSN is set to "pending") [0159] The T1
timer is not started [0160] Next_expected_TSN is set to SN+1 (or
alternatively, SN+x where x is pre-defined or set by higher layers)
[0161] RcvWindow_UpperEdge is set to TSN+y, where y may be
pre-determined or pre-signaled by higher layers [0162] END
[0163] The reordering functionality may be modified such that two
different timers (T_init and T1) may be used. When the reordering
queue is in the "pending" state, the T1 timer used in the
conventional procedure cannot be started. Thus, the conventional
procedure needs to be modified in the following way.
[0164] If no timer T1 is active: [0165] the timer T1 shall be
started when a reordering PDU with TSN>next_expected_TSN is
correctly received, if next_expected_TSN is not set to pending (or
if "reordering_state" is not set to pending); [0166] T1_TSN shall
be set to the TSN of this MAC-hs PDU.
[0167] The second modification is that when the reordering queue is
in the "pending" state, the variable "next_expected_TSN" is not
updated or set and stays set to the value "pending". In addition,
any comparison made with the variable "next_expected_TSN" in the
conventional procedure should have the result "False" when the
reordering queue is in the "pending" state. In case the MAC-ehs
reset procedure sets the variable RcvWindow_UpperEdge to "pending",
this variable needs to be initialized upon reception of the first
reordering PDU. These modifications may be implemented, for
instance, by modifying the conventional procedure. It should be
understood that other formulations to the procedure are also
possible.
[0168] Receiver Operation:
[0169] When a MAC-hs PDU with TSN=SN is received: [0170] (Optional,
in case RcvWindow_UpperEdge" is set to "pending" during MAC-ehs
reset) if the receiver window is "pending" (RcvWindow_UpperEdge set
to "pending") [0171] RcvWindow_UpperEdge shall be set to SN [0172]
if SN is within the receiver window: [0173] if next_expected_TSN is
not set to "pending" and SN<next_expected_TSN, or this MAC-hs
PDU has previously been received: [0174] the MAC-hs PDU shall be
discarded; [0175] else: [0176] the MAC-hs PDU shall be placed in
the reordering buffer at the place indicated by the TSN. [0177] if
SN is outside the receiver window: [0178] the received MAC-hs PDU
shall be placed above the highest received TSN in the reordering
buffer, at the position indicated by SN; [0179] RcvWindow_UpperEdge
shall be set to SN thus advancing the receiver window; [0180] any
MAC-hs PDUs with: [0181]
TSN.ltoreq.RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE, i.e. outside
the receiver window after its position is updated, shall be removed
from the reordering buffer and be delivered to the disassembly
entity; [0182] if next_expected_TSN is not set to "pending" and
next_expected_TSN is below the updated receiver window: [0183]
next_expected_TSN shall be set to
RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1; [0184] if
next_expected_TSN is not set to "pending" and the MAC-hs PDU with
TSN=next_expected_TSN is stored in the reordering buffer: [0185]
all received MAC-hs PDUs with consecutive TSNs from
next_expected_TSN (included) up to the first not received MAC-hs
PDU shall be delivered to the disassembly entity; [0186]
next_expected_TSN shall be advanced to the TSN of this first not
received MAC-hs PDU.
[0187] In case a WTRU has insufficient memory to process a received
reordering PDU, the WTRU performs the following operations: [0188]
select TSN_flush such that:
next_expected_TSN<TSN_flush.ltoreq.RcvWindow_UpperEdge+1 (or any
value if next_expected_TSN is "pending"); [0189] deliver all
correctly received MAC-hs PDUs with TSN<TSN_flush to the
disassembly entity; [0190] if the MAC-hs PDU with TSN-TSN_flush has
previously been received: [0191] deliver all received MAC-hs PDUs
with consecutive TSNs from TSN_flush (included) up to the first not
received MAC-hs PDU to the disassembly entity; [0192] if
next_expected_TSN is not set to "pending" advance next_expected_TSN
to the TSN of this first not received MAC-hs PDU. [0193] else if
next_expected_TSN is not set to "pending": [0194] set
next_expected_TSN to TSN_flush.
[0195] The third modification specifies what is done while the
reordering queue is in the "pending" state, (e.g., while the T_init
timer is active, if this trigger has been selected). The following
needs to be added to the conventional reordering procedure, (it
should be understood that the variable Tinit_TSN may be substituted
for T1_TSN without change of meaning): [0196] If next_expected_TSN
is set to "pending" (or reordering_state is set to "pending") and a
reordering PDU for the given queue is received with TSN=SN: [0197]
(1) (Optional, applicable to the case where T_init is not
immediately started upon MAC-ehs reset procedure.) If no timer
T_init is active [0198] (a) T_init timer is started, [0199] (b)
Tinit_TSN is set to SN. [0200] (2) (Optional, applicable to the
case where T_init is immediately started upon MAC_ehs reset
procedure.) If Tinit_TSN is set to "pending": [0201] (a) Tinit_TSN
is set to SN.
[0202] When T_init timer expires (or when reordering_state is reset
to "normal" for whatever reason): [0203] (1) Optional, applicable
to the case where T_init is immediately started upon MAC_ehs reset
procedure. If Tinit_TSN is set to "pending": [0204] (a) Restart
T_init timer. [0205] (2) If Tinit_TSN is not set to "pending":
[0206] (a) All correctly received reordering PDUs up to and
including Tinit_TSN-1 (or optionally Tinit_TSN) are delivered to
the entity above reordering (i.e. can be an LCH-ID demultiplexer
entity, disassembly, or reassembly entity). [0207] (b) All
correctly received reordering PDUs up to the next not received
reordering PDU with TSN greater than Tinit_TSN shall be delivered
to the entity above reordering. [0208] (c) next_expected_TSN is set
to the TSN of the next not received reordering PDU, optionally with
TSN greater than T1_TSN; and (if applicable) reordering_state
variable is set to "normal". Alternatively, the next_expected_TSN
can always be set to the next not received MAC-ehs PDU with TSN
greater than T1_TSN when the timer expires. [0209] (d) Optionally,
if there still exist some received reordering PDUs that can not be
delivered to higher layer: [0210] (i) timer T1 is started [0211]
(ii) set T1_TSN to the highest TSN among those of the sets pf
MAC-ehs SDUs that can not be delivered
[0212] Alternatively, if the reordering_state variable is used in
the reordering procedure (optional), the next_expected_TSN may be
to RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1 when a reordering PDU
with TSN=SN is received.
[0213] Alternatively, a single timer (T1) may be used. If a single
timer is used, (i.e., T1 timer), the reordering function is
described as follows:
[0214] If no timer T1 is active and next_expected_TSN is not set to
"Pending": [0215] (a) the timer T1 shall be started when a
reordering PDU with TSN>next_expected_TSN is correctly received.
[0216] (b) T1_TSN shall be set to the TSN of this reordering
PDU.
[0217] If no timer T1 is active and next_expected_TSN is set to
"Pending" [0218] (c) the timer T1 shall be started when a
reordering PDU is correctly received [0219] (d) T1_TSN is set to
the TSN of this reordering PDU.
[0220] If a timer T1 is already active: [0221] (e) no additional
timer shall be started, i.e. only one timer T1 may be active at a
given time.
[0222] The timer T1 shall be stopped if: [0223] (f) the reordering
PDU with TSN=T1_TSN can be delivered to the reassembly entity
before the timer expires and next_expected_TSN is not set to
"Pending".
[0224] When the timer T1expires and next_expected_TSN is not set to
"Pending" and T1_TSN>next_expected_TSN: [0225] (g) all correctly
received reordering PDUs with TSN>next_expected_TSN up to and
including T1_TSN-1 shall be delivered to the reassembly entity;
[0226] (h) all correctly received reordering PDUs up to the next
not received reordering PDU shall be delivered to the reassembly
entity. [0227] (i) next_expected_TSN shall be set to the TSN of the
next not received reordering PDU.
[0228] When the timer T1 expires and next_expected_TSN is set to
"Pending" [0229] (j) All correctly received reordering PDUs up to
and including T1_TSN-1 are delivered to the reassembly entity
[0230] (k) All correctly received reordering PDUs up to the next
not received reordering PDU with TSN greater than T1_TSN shall be
delivered to the reassembly entity [0231] (l) next_expected_TSN is
set to the TSN of the next not received reordering PDU, optionally
with TSN greater than T1_TSN
[0232] When the timer T1 is stopped or expires, and there still
exist some received reordering PDUs that can not be delivered to
higher layer: [0233] (m) timer T1 is started [0234] (n) set T1_TSN
to the highest TSN among those of the sets pf MAC-ehs SDUs that can
not be delivered.
[0235] Alternatively, the following may be performed:
[0236] When the timer T1expires and T1_TSN>next_expected_TSN or
next_expected_TSN is set to "Pending": [0237] (a) all correctly
received reordering PDUs with TSN>next_expected_TSN up to and
including T1_TSN-1 shall be delivered to the reassembly entity;
[0238] (b) all correctly received reordering PDUs up to the next
not received reordering PDU shall be delivered to the reassembly
entity. [0239] (c) next_expected_TSN shall be set to the TSN of the
next not received reordering PDU.
[0240] The receiver operation for reordering is described as
follows:
[0241] When a reordering PDU with TSN=SN is received: [0242] (a) if
RcvWindow_UpperEdge is set to "Pending" [0243] (i)
RcvWindow_UpperEdge shall be set to SN [0244] (b) if SN is within
the receiver window: [0245] (i) if next_expected_TSN is not set to
"Pending" and if SN<next_expected_TSN, or this reordering PDU
has previously been received: [0246] (ii) the reordering PDU shall
be discarded; [0247] (c) else: [0248] (i) the reordering PDU shall
be placed in the reordering buffer at the place indicated by the
TSN. [0249] (d) if SN is outside the receiver window: [0250] (i)
the received reordering PDU shall be placed above the highest
received TSN in the reordering buffer, at the position indicated by
SN; [0251] (ii) RcvWindow_UpperEdge shall be set to SN thus
advancing the receiver window; [0252] (iii) any reordering PDU with
TSN I RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE, i.e. outside the
receiver window after its position is updated, shall be removed
from the reordering buffer and be delivered to the reassembly
entity; [0253] (iv) if next_expected_TSN is not set to "pending"
and if next_expected_TSN is below the updated receiver window:
[0254] a. next_expected_TSN shall be set to
RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1; [0255] (e) if
next_expected_TSN is not set to "pending" and if the reordering PDU
with TSN=next_expected_TSN is stored in the reordering buffer:
[0256] (i) all received reordering PDUs with consecutive TSNs from
next_expected_TSN (included) up to the first not received
reordering PDU shall be delivered to the reassembly entity; [0257]
(ii) next_expected_TSN shall be advanced to the TSN of this first
not received reordering PDU.
[0258] In case a WTRU has insufficient memory to process a received
reordering PDU, the WTRU performs the following operations: [0259]
(a) select TSN_flush such that:
next_expected_TSN<TSN_flush.ltoreq.RcvWindow_UpperEdge+1 [or any
value if next_expected_TSN is set to "Pending"]; [0260] (b) deliver
all correctly received reordering PDUs with TSN<TSN_flush to the
reassembly entity; [0261] (c) if the reordering PDU with
TSN=TSN_flush has previously been received: [0262] (i) deliver all
received reordering PDUs with consecutive TSNs from TSN_flush
(included) up to the first not received reordering PDU to the
reassembly entity; [0263] (ii) advance next_expected_TSN to the TSN
of this first not received reordering PDU. [0264] (d) else: [0265]
(i) set next_expected_TSN to TSN_flush.
[0266] In accordance with a seventh embodiment, the Node-Bs may
broadcast the TSN for the next MAC-ehs SDU to be sent for the WTRUs
using the common H-RNTI. This information may be broadcasted in one
of the system information block (SIB) that is originated in the
Node-B. When the WTRU performs a MAC-ehs reset and selects a new
cell, the WTRU reads the SIB containing the TSN number. Upon
acquiring the TSN, the WTRU may perform the following steps: [0267]
(1) Set next_expected_TSN=TSN+1 acquired from SIB; and [0268] (2)
Set Rcv_Window_UpperEdge=TSN This enables the WTRU to properly
process the next received MAC-ehs PDU using a common H-RNTI and
perform reordering.
[0269] Alternatively, the Node-B may provide the TSN on the
HS-SCCH. The TSN may be provided in one or a combination of the
following ways: [0270] (1) For every transmission over a common
H-RNTI; and [0271] (2) Only for the first x (configurable amount of
times) transmission after a WTRU has just been added to the new
cell.
[0272] Alternatively, the Node B and the WTRU may reset the TSN of
a particular queue to a default value. This may be performed
whenever a packet is transmitted to a new WTRU in the cell. The
default value may be signalled through higher layers or
pre-defined. The Node B may signal the reset of the TSN to all
other WTRUs that monitor the H-RNTI. The Node B may signal a TSN
reset using any of the following methods: [0273] (1) Using new or
conventional Layer 3 signalling, (e.g., BCCH or another other RRC
message); [0274] (2) Using new or conventional Layer 2 signalling,
(e.g., the MAC-ehs header may be modified to include TSN reset
information); and [0275] (3) Using new or conventional PHY layer
signalling, (e.g., a modified HS-SCCH format could be used to
indicate a TSN reset.
[0276] In accordance with an eighth embodiment, the network always
ensures that the RRC messages sent over common H-RNTI is small
enough to fit into a single MAC-ehs PDU by minimizing the content
of the message. The RRC message may be "segmented" into smaller RRC
messages. For instance, the initial message may contain the cell
RNTI (C-RNTI) and/or H-RNTI and the rest of the configuration may
be signalled by using separate RRC message(s). After the WTRU gets
its dedicated H-RNTI, subsequent RRC messages may be of any size
since the reordering functionality at MAC-ehs works properly with
the dedicated H-RNTI.
[0277] However, the network needs to ensure that the WTRU has
successfully received the initial RRC message, (e.g., containing
only the C-RNTI and/or H-RNTI), prior to sending subsequent
messages (configuration) using the dedicated H-RNTI. This can be
guaranteed if the RRC entity waits conservatively enough by taking
into account the number of HARQ retransmission and the RRC delay
requirements in the WTRU. Depending on the implementation, the RRC
entity may be "blind" to the delay required by the lower layers to
transmit the message. If this is the case then the RRC needs to
wait for a long time to be sure that the transmission is
completed.
[0278] Additionally, when segmenting the RRC message, an RNC has to
ensure that the size of the generated MAC-ehs SDUs is within a
value such that no segmentation is required at the MAC-ehs entity.
Smallest transport block size available may be used as a reference
of the MAC-ehs PDU size. Alternatively, or in combination, the
transport block size that is going to be used by the Node B may be
inferred from the value of the received measurement results on a
random access channel (RACH) that is included in the "Transmit
Power Level" field.
[0279] If segmentation of the RRC message occurs, the receiver side
may need to be modified such that it acts on the IEs of the
received message as if a single RRC message was sent, (i.e., do not
wait for the other part or segment of the RRC message).
[0280] In accordance with a ninth embodiment, the first received
packets are not delivered immediately. The first received MAC_ehs
PDU is always placed in the reordering buffer and its SN is used to
determine the values of some or all of the reordering variables
(next_expected_TSN, RcvWindow_UpperEdge, T1_TSN). For instance, the
upper edge of the receiver window (RcvWindow_UpperEdge) and/or
T1_TSN may be set to the SN of the received MAC-ehs PDU, and
next_expected_TSN may be set to this SN-RECEIVE_WINDOW_SIZE+1. This
ensures that any subsequently received PDU with lower TSN is not
discarded, but rather is properly stored in the reordering buffer.
Alternatively, next_expected_TSN may be set to a different value,
such as RcvWindow_UpperEdge-x where x is some pre-defined constant.
A timer (either T1 timer or some other timer T1_init) is started
upon reception of this first MAC-ehs PDU. Until expiration of the
timer, all subsequently received MAC-ehs PDUs are placed in the
reordering buffer according to their TSN. These PDUs are not
delivered to the reassembly entity unless they have to be removed
from the reordering buffer as per the conventional procedure.
[0281] When the timer expires, some or all of the PDUs present in
the reordering buffer may be delivered to the reassembly entity.
For instance, all PDUs with TSN up to including T1_TSN-1 may be
delivered, and then, all PDUs up to the next not received PDU may
be delivered. The variable next_expected_TSN may be set (or reset)
to the TSN of this next not received PDU. In addition, the T1 timer
may be restarted at this point if there are still PDUs that cannot
be delivered. In this case, the variable T1_TSN may be set to the
highest TSN among those of the MAC-ehs PDUs that cannot be
delivered. Normal reordering operation proceeds from that
point.
[0282] At least one of the variables next_expected_TSN and
RcvWindow_UpperEdge has its initial value set to a special value
("Pending") so that the WTRU executes the proper operations at the
beginning of the procedure. Alternatively, a new Boolean variable,
(e.g., "Reordering_InitialState") may be defined to indicate
whether the procedure is in its initial state or not. When the
value of this variable is set to "True", the WTRU executes the
procedure as stated above, and the variable is reset to "False" at
the expiration of the initial timer.
[0283] In accordance with one option for the ninth embodiment, the
variable RcvWindow_UpperEdge only has its initial value set to
"Pending" for certain reordering queues subject to the modified
procedure. The T1 timer is started upon reception of the first PDU
when the value of RcvWindow_UpperEdge is "Pending" indicating that
it is in its initial state. The detailed procedure is as
follows:
If no timer T1 is active: [0284] the timer T1 shall be started when
a reordering PDU with TSN>next_expected_TSN is correctly
received, or when a reordering PDU is correctly received and
RcvWindow_UpperEdge is set to "Pending". [0285] T1_TSN shall be set
to the TSN of this reordering PDU. If a timer T1 is already active:
[0286] no additional timer shall be started. i.e. only one timer T1
may be active at a given time. The timer T1 shall be stopped if:
[0287] the reordering PDU with TSN=T1_TSN can be delivered to the
reassembly entity before the timer expires. When the timer T1
expires and T1_TSN>next_expected_TSN: [0288] all correctly
received reordering PDUs with TSN>next_expected_TSN up to and
including T1_TSN-1 shall be delivered to the reassembly entity;
[0289] all correctly received reordering PDUs up to the next not
received reordering PDU shall be delivered to the reassembly
entity. [0290] next_expected_TSN shall be set to the TSN of the
next not received reordering PDU. When the timer T1 is stopped or
expires, and there still exist some received reordering PDUs that
can not be delivered to higher layer: [0291] timer T1 is started
[0292] set T1_TSN to the highest TSN among those of the sets of
MAC-ehs SDUs that can not be delivered.
Transmitter Operation:
[0293] After the transmitter has transmitted a reordering PDU with
TSN=SN, any reordering PDU with TSN.ltoreq.SN-TRANSMIT_WINDOW_SIZE
should not be retransmitted to avoid sequence number ambiguity in
the receiver.
Receiver Operation:
[0294] When a reordering PDU with TSN=SN is received: [0295] if
RcvWindow_UpperEdge is set to "Pending": [0296] RcvWindow_UpperEdge
shall be set to SN; [0297] next_expected_TSN shall be set to
RcvWindow_UpperEdge-WINDOW_SIZE+1. [0298] if SN is within the
receiver window: [0299] if SN<next_expected_TSN, or this
reordering PDU has previously been received: [0300] the reordering
PDU shall be discarded; [0301] else: [0302] the reordering PDU
shall be placed in the reordering buffer at the place indicated by
the TSN. [0303] if SN is outside the receiver window: [0304] the
received reordering PDU shall be placed above the highest received
TSN in the reordering buffer, at the position indicated by SN;
[0305] RcvWindow_UpperEdge shall be set to SN thus advancing the
receiver window; [0306] any reordering PDU with
TSN.ltoreq.RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE, i.e. outside
the receiver window after its position is updated, shall be removed
from the reordering buffer and be delivered to the reassembly
entity; [0307] if next_expected_TSN is below the updated receiver
window: [0308] next_expected_TSN shall be set to
RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1; [0309] if the reordering
PDU with TSN=next_expected_TSN is stored in the reordering buffer:
[0310] all received reordering PDUs with consecutive TSNs from
next_expected_TSN (included) up to the first not received
reordering PDU shall be delivered to the reassembly entity; [0311]
next_expected_TSN shall be advanced to the TSN of this first not
received reordering PDU. In case a WTRU has insufficient memory to
process a received reordering PDU, it shall perform the following
set of operations: [0312] select TSN_flush such that:
next_expected_TSN<TSN_flush.ltoreq.RcvWindow_UpperEdge+1; [0313]
deliver all correctly received reordering PDUs with
TSN<TSN_flush to the reassembly entity; [0314] if the reordering
PDU with TSN=TSN_flush has previously been received: [0315] deliver
all received reordering PDUs with consecutive TSNs from TSN_flush
(included) up to the first not received reordering PDU to the
reassembly entity; [0316] advance next_expected_TSN to the TSN of
this first not received reordering PDU. [0317] else: [0318] set
next_expected_TSN to TSN_flush.
[0319] In accordance with a second option for the ninth embodiment,
the variables next_expected_TSN and RcvWindow_UpperEdge both have
their initial values set to "Pending" for certain reordering queues
subject to the modified procedure. Upon reception of the first PDU
the variables RcvWindow_UpperEdge and T1_TSN are set to the SN of
this PDU, while next_expected_TSN remains set to the value
"Pending". In addition, the timer T1 is started. Comparison between
the SN of the received PDUs and next_expected_TSN is skipped when
next_expected_TSN is set to "Pending". After the timer T1 expires
or is stopped (the latter may happen if the PDU with SN equal to
T1_TSN may be delivered due to the advancing receiver window), all
PDUs with SN up to T1_TSN-1, and with SN up to the next not
received PDU, are delivered to the reassembly entity. The value of
next_expected_TSN is set to the SN of the next not received PDU and
normal reordering operation can proceed from that point. The
detailed procedure is as follows:
If no timer T1 is active and next_expected_TSN is not set to
"Pending": [0320] the timer T1 shall be started when a reordering
PDU with TSN>next_expected_TSN is correctly received. [0321]
T1_TSN shall be set to the TSN of this reordering PDU. If no timer
T1 is active and next_expected_TSN is set to "Pending": [0322] the
timer T1 shall be started when a reordering PDU is correctly
received [0323] T1_TSN is set to the TSN of this reordering PDU. If
a timer T1 is already active: [0324] no additional timer shall be
started, i.e. only one timer T1 may be active at a given time. The
timer T1 shall be stopped if: [0325] the reordering PDU with
TSN=T1_TSN can be delivered to the reassembly entity before the
timer expires. When the timer T1 expires and next_expected_TSN is
not set to "Pending" and T1_TSN>next_expected_TSN: [0326] all
correctly received reordering PDUs with TSN>next_expected_TSN up
to and including T1_TSN-1 shall be delivered to the reassembly
entity; [0327] all correctly received reordering PDUs up to the
next not received reordering PDU shall be delivered to the
reassembly entity. [0328] next_expected_TSN shall be set to the TSN
of the next not received reordering PDU. When the timer T1 is
stopped or expires and next_expected_TSN is set to "Pending":
[0329] All correctly received reordering PDUs up to and including
T1_TSN-1 are delivered to the reassembly entity. [0330] All
correctly received reordering PDUs up to the next not received
reordering PDU with TSN greater than T1_TSN shall be delivered to
the reassembly entity. [0331] next_expected_TSN is set to the TSN
of the next not received reordering PDU with TSN greater than
T1_TSN. When the timer T1 is stopped or expires, and there still
exist some received reordering PDUs that can not be delivered to
higher layer: [0332] timer T1 is started [0333] set T1_TSN to the
highest TSN among those of the sets pf MAC-ehs SDUs that can not be
delivered.
Transmitter Operation:
[0334] After the transmitter has transmitted a reordering PDU with
TSN=SN, any reordering PDU with TSN.ltoreq.SN-TRANSMIT_WINDOW_SIZE
should not be retransmitted to avoid sequence number ambiguity in
the receiver.
Receiver Operation:
[0335] When a reordering PDU with TSN=SN is received: [0336] if
RcvWindow_UpperEdge is set to "Pending": [0337] RcvWindow_UpperEdge
shall be set to SN. [0338] if SN is within the receiver window:
[0339] if next_expected_TSN is not set to "Pending" and
SN<next_expected_TSN, or this reordering PDU has previously been
received: [0340] the reordering PDU shall be discarded; [0341]
else: [0342] the reordering PDU shall be placed in the reordering
buffer at the place indicated by the TSN. [0343] if SN is outside
the receiver window: [0344] the received reordering PDU shall be
placed above the highest received TSN in the reordering buffer, at
the position indicated by SN; [0345] RcvWindow_UpperEdge shall be
set to SN thus advancing the receiver window; [0346] any reordering
PDU with TSN RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE, i.e. outside
the receiver window after its position is updated, shall be removed
from the reordering buffer and be delivered to the reassembly
entity; [0347] if next_expected_TSN is not set to "Pending" and
next_expected_TSN is below the updated receiver window: [0348]
next_expected_TSN shall be set to
RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1; [0349] if
next_expected_TSN is not set to "Pending" and the reordering PDU
with TSN=next_expected_TSN is stored in the reordering buffer:
[0350] all received reordering PDUs with consecutive TSNs from
next_expected_TSN (included) up to the first not received
reordering PDU shall be delivered to the reassembly entity; [0351]
next_expected_TSN shall be advanced to the TSN of this first not
received reordering PDU. In case a WTRU has insufficient memory to
process a received reordering PDU, it shall perform the following
set of operations: [0352] select TSN_flush such that:
next_expected_TSN<TSN_flush.ltoreq.RcvWindow_UpperEdge+1, or (in
case next_expected_TSN is set to "Pending"),
RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE<TSN_flush.ltoreq.RcvWindow_Upp-
erEdge+1; [0353] deliver all correctly received reordering PDUs
with TSN<TSN_flush to the reassembly entity; [0354] if the
reordering PDU with TSN=TSN_flush has previously been received:
[0355] deliver all received reordering PDUs with consecutive TSNs
from TSN_flush (included) up to the first not received reordering
PDU to the reassembly entity; [0356] advance next_expected_TSN to
the TSN of this first not received reordering PDU. [0357] else:
[0358] set next_expected_TSN to TSN_flush.
[0359] In accordance with a third option for the ninth embodiment,
RcvWindow_UpperEdge and next_expected_TSN keep their initial values
as in the conventional art, and a new variable
"Reordering_InitialState" is defined and takes the initial value
"True" for those reordering queues subject to the modified
procedure. The condition for starting the T1 timer is modified to
ensure that the timer is started upon reception of the first PDU
when the value of Reordering_InitialState is "True" indicating that
it is in its initial state. The WTRU first checks whether
Reordering_InitialState is set to "True" before handling the
received MAC-ehs PDU. If this is the case, the variable
RcvWindow_UpperEdge is set to the SN of the PDU, the variable
next_expected_TSN is set to the lower edge of the receiver window
and the variable Reordering_InitialState is set to "False" to
return to the normal state. The detailed procedure is as
follows:
If no timer T1 is active: [0360] the timer T1 shall be started when
a reordering PDU with TSN>next_expected_TSN is correctly
received, or when a reordering PDU is correctly received and
Reordering_InitialState is set to "True". [0361] T1_TSN shall be
set to the TSN of this reordering PDU. If a timer T1 is already
active: [0362] no additional timer shall be started, i.e. only one
timer T1 may be active at a given time. The timer T1 shall be
stopped if: [0363] the reordering PDU with TSN=T1_TSN can be
delivered to the reassembly entity before the timer expires. When
the timer T1 expires and T1_TSN>next_expected_TSN: [0364] all
correctly received reordering PDUs with TSN>next_expected_TSN up
to and including T1_TSN-1 shall be delivered to the reassembly
entity; [0365] all correctly received reordering PDUs up to the
next not received reordering PDU shall be delivered to the
reassembly entity. [0366] next_expected_TSN shall be set to the TSN
of the next not received reordering PDU. When the timer T1 is
stopped or expires, and there still exist some received reordering
PDUs that can not be delivered to higher layer: [0367] timer T1 is
started [0368] set T1_TSN to the highest TSN among those of the
sets pf MAC-ehs SDUs that can not be delivered.
Transmitter Operation:
[0369] After the transmitter has transmitted a reordering PDU with
TSN=SN, any reordering PDU with TSN.ltoreq.SN-TRANSMIT_WINDOW_SIZE
should not be retransmitted to avoid sequence number ambiguity in
the receiver.
Receiver Operation:
[0370] When a reordering PDU with TSN=SN is received: [0371] if
Reordering_InitialState is set to "True": [0372]
RcvWindow_UpperEdge shall be set to SN; [0373]
Reordering_InitialState shall be set to "False"; [0374]
next_expected_TSN shall be set to
RcvWindow_UpperEdge-WINDOW_SIZE+1. [0375] if SN is within the
receiver window: [0376] if SN<next_expected_TSN, or this
reordering PDU has previously been received: [0377] the reordering
PDU shall be discarded; [0378] else: [0379] the reordering PDU
shall be placed in the reordering buffer at the place indicated by
the TSN. [0380] if SN is outside the receiver window: [0381] the
received reordering PDU shall be placed above the highest received
TSN in the reordering buffer, at the position indicated by SN;
[0382] RcvWindow_UpperEdge shall be set to SN thus advancing the
receiver window; [0383] any reordering PDU with
TSN.ltoreq.RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE, i.e. outside
the receiver window after its position is updated, shall be removed
from the reordering buffer and be delivered to the reassembly
entity; [0384] if next_expected_TSN is below the updated receiver
window: [0385] next_expected_TSN shall be set to
RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1; [0386] if the reordering
PDU with TSN=next_expected_TSN is stored in the reordering buffer:
[0387] all received reordering PDUs with consecutive TSNs from
next_expected_TSN (included) up to the first not received
reordering PDU shall be delivered to the reassembly entity; [0388]
next_expected_TSN shall be advanced to the TSN of this first not
received reordering PDU. In case a WTRU has insufficient memory to
process a received reordering PDU, it shall perform the following
set of operations: [0389] select TSN_flush such that:
next_expected_TSN<TSN_flush.ltoreq.RcvWindow_UpperEdge+1; [0390]
deliver all correctly received reordering PDUs with
TSN<TSN_flush to the reassembly entity; [0391] if the reordering
PDU with TSN=TSN_flush has previously been received: [0392] deliver
all received reordering PDUs with consecutive TSNs from TSN_flush
(included) up to the first not received reordering PDU to the
reassembly entity; [0393] advance next_expected_TSN to the TSN of
this first not received reordering PDU. [0394] else: [0395] set
next_expected_TSN to TSN_flush.
[0396] In accordance with a fourth option for the ninth embodiment,
the reordering functionality may start with an initial window size,
(i.e., RECEIVE_WINDOW_SIZE), of 64, which spans all the possible
sequence numbers for the queue. This will ensure that during the
initial phase no reordering PDUs are discarded. Upon reception of
the first reordering PDU, the T1 timer is started with T1_TSN set
to the SN of the first received MAC-ehs PDU, unless reordering PDU
with SN set to 0 is received.
[0397] When the timer expires, some or all of the PDUs present in
the reordering buffer are delivered to the reassembly entity
according to the following rules:
[0398] (1) All PDUs with TSN up to including T1_TSN-1 shall be
delivered to higher layers;
[0399] (2) All PDUs up to the next not received PDU shall be
delivered to higher layers;
[0400] (3) next_expected_TSN may be set to the TSN of the next not
received PDU (alternatively, specify set it to the next not
received PDU with TSN greater than T1_TSN);
[0401] (4) The RcvWindow_UpperEdge is set to the highest sequence
number of a reordering PDU received; and
[0402] (5) The RECEIVE_WINDOW_SIZE variable is restored and set to
the configured normal operation value.
[0403] In addition, the T1 timer may be restarted at this point if
there are still PDUs that cannot be delivered. In this case, the
variable T1_TSN is set to the highest TSN among those of the
MAC-ehs PDUs that cannot be delivered. Normal reordering operation
proceeds from that point.
[0404] It should also be noted that for all the options 1 through
4, a separate new timer may optionally be introduced, (i.e.,
T1_init), for the initial phase. In order to utilize a separate
timer the paragraph of the procedure where it is checked "If no
timer T1 is active:" is modified as follows:
If no timer T1 or T1_init is active: [0405] If RcvWindow_UpperEdge
(or next_expected_TSN) is not set to "Pending" (or optionally
Reordering_InitialState is set to "FALSE"), the timer T1 shall be
started when a reordering PDU with TSN>next_expected_TSN or is
correctly received. [0406] If RcvWindow_UpperEdge (or
next_expected_TSN) is set to "Pending" (or optionally if
Reordering_InitialState is set to "TRUE"), the timer T1_init shall
be started when a reordering is correctly received.
[0407] All other actions related to the stopping and expiration of
the timer remain similar to the actions related to T1 timer. When
T1_init timer expires, the reordering entity must ensure that T1
timer is restarted if there are still PDUs that cannot be
delivered. These changes are highlighted in the following:
If a timer T1 or T1_init is already active: [0408] no additional
timer shall be started, i.e. only one timer T1 (or T1_init) may be
active at a given time. The timer T1 or T1_init shall be stopped
if: [0409] the reordering PDU with TSN=T1_TSN can be delivered to
the reassembly entity before the timer expires. When the timer T1
or T1_init expires and T1_TSN>next_expected_TSN: [0410] all
correctly received reordering PDUs with TSN>next_expected_TSN up
to and including T1_TSN-1 shall be delivered to the reassembly
entity; [0411] all correctly received reordering PDUs up to the
next not received reordering PDU shall be delivered to the
reassembly entity. [0412] next_expected_TSN shall be set to the TSN
of the next not received reordering PDU. When the timer T1 or
T1_init is stopped or expires, and there still exist some received
reordering PDUs that can not be delivered to higher layer: [0413]
timer T1 is started [0414] set T1_TSN to the highest TSN among
those of the sets pf MAC-ehs SDUs that can not be delivered.
[0415] In accordance with a tenth embodiment, an explicit
systematic setting of the initial T1 timer upon reception of the
first reordering PDU may be avoided. For example, the first
reordering PDU may be immediately delivered to higher layers and
the value of its SN is used to determine the values of some of the
reordering variables. In order to achieve this one or a combination
of the following options may be used:
[0416] In accordance with a first option, the procedure starts in
an "initial" state using one of the methods disclosed above, (e.g.,
next_expected_TSN and/or RcvWindow_UpperEdge is initialized to
"Pending", or a new variable is defined for the initial state).
When the first reordering PDU is received, next_expected_TSN is set
to SN+1 and RcvWindow_UpperEdge is set to SN. The reordering queue
continues the normal mode of operation for all subsequently
received reordering PDUs.
[0417] The first option may result in subsequently received PDUs
with SN<next_expected_TSN being discarded. In order to avoid
discarding of PDUs, in accordance with a second option, a new
initial_TSN variable is maintained that contains the TSN number of
the first received PDU. The first received PDU is delivered to
higher layers and Initial_TSN is set to SN, next_expected_TSN is
set to SN+1, and RcvWindow_UpperEdge is set to SN.
[0418] Reordering PDUs with SN<initial_TSN may not be discarded
until the lower edge of the window, (i.e.,
RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE), has moved past the value
of the initial_TSN. All reordering PDUs with SN<initial_TSN may
be immediately delivered to the reassembly entity or directly to
LCH-ID demux entity (without performing the reassembly). Reordering
PDUs with SN>initial_TSN may be normally processed by the
reordering procedure. Optionally, in order to avoid duplication of
data a list of received PDUs can be maintained until the lower edge
of the window has moved past the initial TSN. Alternatively, the
reordering PDUs SN<initial_TSN may not be discarded (and are
delivered to higher layers) until a certain timer expires (T1 or a
new timer).
[0419] An example procedure is described below.
[0420] If no timer T1 is active: [0421] the timer T1 shall be
started when a reordering PDU with TSN>next_expected_TSN is
correctly received. [0422] T1_TSN shall be set to the TSN of this
reordering PDU.
[0423] If a timer T1 is already active: [0424] no additional timer
shall be started, (i.e., only one timer T1 may be active at a given
time).
[0425] The timer T1 shall be stopped if: [0426] the reordering PDU
with TSN=T1_TSN can be delivered to the reassembly entity before
the timer expires.
[0427] When the timer T1 expires and T1_TSN>next_expected_TSN:
[0428] all correctly received reordering PDUs with
TSN>next_expected_TSN up to and including T1_TSN-1 shall be
delivered to the reassembly entity; [0429] all correctly received
reordering PDUs up to the next not received reordering PDU shall be
delivered to the reassembly entity. [0430] next_expected_TSN shall
be set to the TSN of the next not received reordering PDU. [0431]
if reordering_InitState is set to "TRUE", reordering_InitState
shall be set to "FALSE"
[0432] When the timer T1 is stopped or expires, and there still
exist some received reordering PDUs that can not be delivered to
higher layer: [0433] timer T1 is started [0434] set T1_TSN to the
highest TSN among those of the sets pf MAC-ehs SDUs that can not be
delivered.
Transmitter Operation:
[0435] After the transmitter has transmitted a reordering PDU with
TSN=SN, any reordering PDU with TSN.ltoreq.SN-TRANSMIT_WINDOW_SIZE
should not be retransmitted to avoid sequence number ambiguity in
the receiver.
Receiver Operation:
[0436] When a reordering PDU with TSN=SN is received: [0437] If
initial_TSN is set to "Pending" [0438] RcvWindow_UpperEdge shall be
set to SN; [0439] next_expected_TSN shall be set to SN+1 [0440]
initial_TSN shall be set to SN [0441] deliver the reordering PDU to
reassembly entity [0442] if SN is within the receiver window [0443]
if reordering_State is set to "TRUE" and if SN<initial_TSN
[0444] the reordering PDU shall be sent to the reassembly entity
(or optionally it can bypass reassembly entity and be sent directly
to LCH-ID demux entity) [0445] else if reordering_InitState if set
to "FALSE" and if SN<next_expected_TSN, or this reordering PDU
has previously been received: [0446] the reordering PDU shall be
discarded; [0447] else: [0448] the reordering PDU shall be placed
in the reordering buffer at the place indicated by the TSN. [0449]
if SN is outside the receiver window: [0450] the received
reordering PDU shall be placed above the highest received TSN in
the reordering buffer, at the position indicated by SN; [0451]
RcvWindow_UpperEdge shall be set to SN thus advancing the receiver
window; [0452] any reordering PDU with
TSN.ltoreq.RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE, i.e. outside
the receiver window after its position is updated, shall be removed
from the reordering buffer and be delivered to the reassembly
entity; [0453] if initial_TSN is below the updated receiver window
[0454] reordering_InitState_is set to "FALSE" [0455] if
next_expected_TSN is below the updated receiver window: [0456]
next_expected_TSN shall be set to
RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1;
[0457] Alternatively, upon reception of first received reordering
PDU, next_expected_TSN may be set to SN-x, where x can be a static
value, a configurable number by higher layers, or a predetermined
value based on the number of HARQ processes, (e.g., if only 4 HARQ
processes are used, x may be set to 4 or maybe the number of HARQ
processes-1). The RcvWindow_UpperEdge is set to SN. This ensures
that some of reordering PDUs with SN<SN-x will not be discarded
for the initial procedure.
[0458] Alternatively, the initial value of next_expected_TSN may be
set the lower edge of the initial window,
RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1 instead of being set to 0
as in the prior art. The initial value of RcvWindow_UpperEdge may
be set to 63.
[0459] In addition, the reordering procedure may be modified by
means of changing the initial window size. For example, two
receiver window sizes may be configured, a small initial receiver
window size and a normal operation receiver window configured by
higher layers. The initial window size may be set to a smaller
value to speed up the initial process and avoid waiting for long T1
timer to expire. In order to return to the normal state of
reordering operation the WTRU may wait for n (n corresponds to the
small initial window size) consecutive reordering PDUs to be
received, or for the lower edge of the window to move past the SN
of the initial received PDU, or for a timer to expire. When
entering the normal operation the normal configured WINDOW_SIZE may
be configured and restored.
[0460] The window size may also be set to a value of zero or one.
With the value set to one, the probability of receiving the first
PDU within the window and thus discarding it is significantly
reduced. The WTRU may be configured such that the receive window is
initially set to this small value and upon reception of the first
PDU the receive window is set back to the configured
RECEIVE_WINDOW_SIZE.
[0461] In accordance with an eleventh embodiment, the reordering
entity may use the HARQ process information as an indication to
start the normal reordering operation. This method may be used
alone or in a combination with any embodiments described herein.
During initial operation, the WTRU may ensure that the reordering
PDU with the lowest possible sequence is received from the cell,
when all the HARQ processes have a new assignment. All received
reordering PDUs are stored in the reordering buffer until either
all new HARQ processes have a new assignment or until the T1 timer
expires.
[0462] The NDI bit of each HARQ process may be monitored. When the
NDI bit for all active processes toggles from `0` to `1`
(indicating a new transmission on the HARQ process), the reordering
entity may deliver all stored PDU up to and including the first
received reordering PDU to the reassembly entity. All other PDUs up
to the first not received PDU above the first received PDU may also
be delivered to higher layer. Next_expected_TSN may be set to SN of
the first not received PDU and the RcvWindow_UpperEdge is set to
the SN of the highest received TSN. T1 timer should be stopped if
it is running.
[0463] Alternatively, a mapping between the HARQ process and
possible TSN values may be maintained. When at least one reordering
PDU from every HARQ process is successfully received, or has failed
to be received successfully, the WTRU has ensured that no other
reordering PDUs with sequence numbers lower than any of the ones
received will be transmitted. The WTRU may set the
RcvWindow_UpperEdge to the SN of the highest received TSN and
next_expected_TSN to the first not received PDU with SN higher than
the lowest received reordering PDU.
[0464] In another option, when the WTRU receives the first
reordering PDU, the WTRU may check the TSN of all PDUs in all
active HARQ processes. If the sequence numbers of the PDUs being
processed in the HARQ process are higher than the first PDU
received, the WTRU may resume normal operation. Otherwise, the WTRU
may wait until the reordering PDU with the lowest sequence number
in the HARQ processes is received.
[0465] The network may also define the relationship between the
HARQ process ID and a set of possible TSNs for each HARQ process.
For instance, it may be configured that HARQ process #m would only
handle PDUs with TSN that satisfy TSN=4 n+m, where n is an integer.
This relationship may be pre-signaled to the WTRU by higher layers.
The WTRU may then use this relationship to deduce when the lowest
SN PDU is received and thus resume normal operation.
[0466] One may envision a network based solution that restricts the
use of the full TSN number space, (i.e., the network avoids using
TSN 55 to 63). If the receive window size is equal to or less than
the TSNs not used by the network, this will eliminate the
probability of discarding the first PDUs received. However, this
solution may lead to additional delays and the possibility of
delivering PDUs out of order. In order to avoid this, the following
options may be implemented.
[0467] In accordance with a first option, the WTRU may use a modulo
x, where x is the lowest TSN number restricted, (i.e., if 55 to 63
are restricted, x will be 55), for all arithmetic operations of the
reordering entity. For example, all arithmetic operations contained
in the reordering procedure on next_expected_TSN,
RcvWindow_UpperEdge, T1_TSN and TSN_flush are affected by the x
modulus.
[0468] The x modulus may affect the operations at all times for
reordering of CCCH or DCCH (SRB#1). For the initial operation, the
RcvWindow_UpperEdge may be 63 or any other value above x. The
modulo x should not be applied to this initial value of
RcvWindow_UpperEdge or the initial value may be considered as an
undefined initial value. Using this value may be considered as
equivalent to setting to the value of RcvWindow_UpperEdge to
"Pending". When the RcvWindow_UpperEdge is set to 63, upon
reception of the first PDU with TSN=SN, one or a combination of the
following operations may be performed: [0469] (1) Start using
modulo x for all arithmetic operations; [0470] (2)
RcvWindow_UpperEdge shall be set to SN; [0471] (3)
next_expected_TSN shall be set to
RcvWindow_UpperEdge-WINDOW_SIZE+1; and [0472] (4) Start T1 timer or
T1_init timer.
[0473] Alternatively, two different modulo operations may be used
for the initial and normal state of operation. For example, for the
initial state of operation the normal modulo 64 may be used. The
initial RcvWindow_UpperEdge is set to 63, the lower edge of the
window is within the restricted TSNs and thus no data will be
discarded. However, when entering normal operation state, (i.e.,
upon reception of the first PDU or when T1 timer expires), the
reordering procedure may update the arithmetic procedures based on
the modulo x operation. This will avoid duplicate T1 delays.
Optionally, the four steps described above of setting
RcvWindow_UpperEdge, next_expected_TSN, T1, and start of using
modulo x, may also be performed.
[0474] In accordance with a second option, modulo 64 is used at all
times but the procedure is modified such that it takes into
consideration the missing TSN space. One of the above mentioned
methods may be used to indicate the reordering state operation,
(i.e., either initial or normal reordering state): [0475]
next_expected_TSN or RcvWindow_UpperEdge set to a special value,
"Pending"; and [0476] new state variable.
[0477] The WTRU enters normal state of reordering operation either
when the first PDU is received or when T1 timer expires. For the
initial state of operation the arithmetic procedures remain
unchanged. Since the TSN space is restricted, the first PDU
received will never be within the receive window and thus it will
not be discarded. However, when entering normal state the
reordering procedure must be updated in order to avoid out of order
delivery and duplicate T1 timers. For the purpose of describing
this procedures the following variables will be used: [0478] TSN
space will be restricted from x to y, where x is the lower value of
the restricted space and y is the upper value of the restricted
space, (i.e., 63); [0479] RcvWindow_lowerEdge is equivalent to
RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1; [0480] Nr_restrictedTSNs
is equivalent to the number of TSNs that are restricted from being
used, y-x.
[0481] When operating in normal state the reordering procedure is
modified such that: [0482] When x<=RcvWindow_lowerEdge<=y,
then the receiver window defined is equivalent to
RcvWindow_lowerEdge-Nr_restrictedTSNs; [0483] Else the receive
window is calculated as
(RcvWindow_UpperEdge-RECEIVE_WINDOW_SIZE+1); [0484]
next_expected_TSN should not be set to a value between x and y;
[0485] If next_expected_TSN is x-1, then next in order MAC-ehs PDU
to be expected is considered to be y+1; [0486] The reordering
procedure may consider all TSN numbers from x to y as successfully
received PDUs when performing reordering and when it is considered
to be waiting for those TSNs
[0487] Optionally, upon reception of the first PDU the variables
may be set the following way: [0488] (1) RcvWindow_UpperEdge shall
be set to SN; [0489] (2) next_expected_TSN shall be set to
RcvWindow_UpperEdge-WINDOW_SIZE+1; and [0490] (3) Start T1 timer or
T1_init timer.
[0491] In accordance with a twelfth embodiment, the reordering
problem may be solved on the network side, instead of the receiver
side. The Node B may maintain different TSN numbers for each WTRU
independently within each common H-RNTI. When a new WTRU is added
to the cell, the Node B may start numbering the reordering PDUs for
this WTRU from zero. The TSN numbers are incremented for each WTRU
independently. This solution would require the Node B to know the
unique WTRU ID to which it is transmitting in addition to the
common H-RNTI. The Iub frame protocol may provide the common
H-RNTI. In this embodiment the dedicated H-RNTI that the network
has provided for this WTRU should also be provided.
[0492] Alternatively, the RNC may provide an indication that the
message to be transmitted is for a new WTRU. When the Node B
receives this indication the Node B may perform one or a
combination of the following: [0493] Reset TSN numbers associated
with the common H-RNTI group right away; or [0494] Ensure that any
previously buffered MAC-ehs PDUs with the same common H-RNTI have
been transmitted and then reset the TSN numbers, such that the
message for the new WTRU is sent with the initial TSN to zero.
[0495] Since the other WTRUs associated to the cell with the same
common H-RNTI will be receiving the data for the new cell, it might
be preferable to indicate to these WTRUs that the TSN number has
been reset. This can be indicated by a bit in the HS-SCCH.
[0496] 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).
[0497] 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.
[0498] 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.
* * * * *