U.S. patent application number 14/065794 was filed with the patent office on 2014-02-27 for method and apparatus for indicating a temporary block flow to which a piggybacked ack/nack field is addressed.
This patent application is currently assigned to InterDigital Technology Corporation. The applicant listed for this patent is InterDigital Technology Corporation. Invention is credited to Behrouz Aghili, Prabhakar R. Chitrapu, Stephen G. Dick, Marian Rudolf.
Application Number | 20140056255 14/065794 |
Document ID | / |
Family ID | 39737034 |
Filed Date | 2014-02-27 |
United States Patent
Application |
20140056255 |
Kind Code |
A1 |
Aghili; Behrouz ; et
al. |
February 27, 2014 |
METHOD AND APPARATUS FOR INDICATING A TEMPORARY BLOCK FLOW TO WHICH
A PIGGYBACKED ACK/NACK FIELD IS ADDRESSED
Abstract
Methods and apparatus are described. A wireless transmit/receive
unit (WTRU) generates a piggybacked
acknowledgement/non-acknowledgement (PAN) field and a PAN check
sequence (PCS) from the PAN field. The WTRU masks the PCS with a
temporary flow identity (TFI) that includes a specific sequence of
a plurality of bit values that represents information other than an
identification of a particular TBF. The WTRU transmits data that
includes the PAN field and the masked PCS.
Inventors: |
Aghili; Behrouz; (Commack,
NY) ; Dick; Stephen G.; (Nesconset, NY) ;
Rudolf; Marian; (Montreal, CA) ; Chitrapu; Prabhakar
R.; (Blue Bell, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
InterDigital Technology Corporation |
Wilmington |
DE |
US |
|
|
Assignee: |
InterDigital Technology
Corporation
Wilmington
DE
|
Family ID: |
39737034 |
Appl. No.: |
14/065794 |
Filed: |
October 29, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12133593 |
Jun 5, 2008 |
8572451 |
|
|
14065794 |
|
|
|
|
60942370 |
Jun 6, 2007 |
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Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04L 1/0057 20130101;
H04L 1/1664 20130101; H04L 1/0061 20130101; H04L 5/0053 20130101;
H04L 1/1867 20130101; H04L 1/1896 20130101 |
Class at
Publication: |
370/329 |
International
Class: |
H04L 5/00 20060101
H04L005/00 |
Claims
1. A method for use in a wireless transmit/receive unit (WTRU), the
method comprising: the WTRU generating a piggybacked
acknowledgement/non-acknowledgement (PAN) field; the WTRU
generating a PAN check sequence (PCS) from the PAN field; the WTRU
masking the PCS with a temporary flow identity (TFI) that includes
a specific sequence of a plurality of bit values that represents
information other than an identification of a particular TBF; and
the WTRU transmitting data that includes the PAN field and the
masked PCS.
2. The method of claim 1, wherein the plurality of bit values is
five bit values.
3. The method of claim 2, wherein each of the five bit values is
zero.
4. The method of claim 1, wherein the masking the PCS further
comprises adding the TFI modulo-2 to a last five bits of the
PCS.
5. The method of claim 1, wherein the information other than the
identification of a particular TBF is an indication that the WTRU
is assigned one TBF in the uplink direction.
6. The method of claim 1, wherein the information other than the
identification of a particular TBF is information regarding an
action affecting the WTRU.
7. The method of claim 1, wherein the information other than the
identification of a particular TBF is an indication that the PAN
field is to be decoded by more than one WTRU.
8. A wireless transmit/receive unit (WTRU) comprising: a processor
configured to: generate a piggybacked
acknowledgement/non-acknowledgement (PAN) field, generate a PAN
check sequence (PCS) from the PAN field, and mask the PCS with a
temporary flow identity (TFI) that includes a specific sequence of
a plurality of bit values that represents information other than an
identification of a particular TBF; and a transmitter configured to
transmit data that includes the PAN field and the masked PCS.
9. The WTRU of claim 8, wherein the plurality of bit values is five
bit values.
10. The WTRU of claim 8, wherein each of the five bit values is
zero.
11. The WTRU of claim 8, wherein the processor is further
configured to mask the PCS by adding the TFI modulo-2 to a last
five bits of the PCS.
12. The WTRU of claim 8, wherein the information other than an
identification of a particular TBF is an indication that the WTRU
is assigned one TBF in the uplink direction.
13. The WTRU of claim 8, wherein the information other than the
identification of a particular TBF is information regarding an
action affecting the WTRU.
14. The WTRU of claim 8, wherein the information other than the
identification of a particular TBF is an indication that the PAN
field is to be decoded by more than one WTRU.
15. A base station comprising: a receiver configured to receive
data that includes a piggybacked acknowledgement/non-acknowledgment
(PAN) field and a masked PAN check sequence (PCS), the masked PCS
being masked by a PCS generated from the PAN field with a temporary
flow identity (TFI) that includes a specific sequence of a
plurality of bit values that represents information other than an
identification of a particular TBF; and a processor configured to
decode the masked PCS using the TFI value.
16. The base station of claim 15, wherein the plurality of bit
values is five bit values.
17. The base station of claim 15, wherein each of the five bit
values is zero.
18. The base station of claim 15, wherein the information other
than an identification of a particular TBF is an indication that a
particular receiving station is assigned one TBF in the uplink
direction.
19. The base station of claim 15, wherein the information other
than the identification of a particular TBF is information
regarding an action affecting a particular receiving station.
20. The base station of claim 15, wherein the information other
than the identification of a particular TBF is an indication that
the PAN field is to be decoded by more than one receiving station.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/133,593, filed Jun. 5, 2008, which claims
the benefit of U.S. provisional application No. 60/942,370 filed
Jun. 6, 2007, which is/are incorporated by reference as if fully
set forth.
FIELD OF INVENTION
[0002] The present invention is related to wireless
communications.
BACKGROUND
[0003] Latency reduction is one of the well recognized work items
in GSM/EDGE Release 7 radio access network (GERAN) evolution. There
are primarily two techniques being worked on in this area; namely
the reduced transmission time interval (RTTI) feature and the fast
positive acknowledgement/negative acknowledgement (ACK/NACK)
reporting (FANR) feature.
[0004] Both the RTTI feature and the FANR feature can either work
separately, or in conjunction with each other. Furthermore, both
the RTTI feature and the FANR feature can be used in conjunction
with evolved general packet radio services (EGPRS) modulation and
coding schemes MCS-1 to MCS-9 (except for MCS-4 and MCS-9 where
FANR cannot be implemented) or with the novel Release 7 and beyond
EGPRS-2 modulation and coding schemes DAS-5 to DAS-12, DBS-5 to
DBS-12, UAS-7 to UAS-11 and UBS-5 to UBS-12. RTTI mode of operation
and FANR mode of operation are also possible with other existing
Release 7 GERAN evolution features, such as the Downlink
Dual-Carrier (DLDC) feature or Downlink Advanced Receiver
Performance (DARP) operation.
[0005] In the prior art described by pre-Release 7 global system
for mobile communication (GSM), general packet radio services
(GPRS) and EGPRS modes of operation, an ACK/NACK report was
typically sent in explicit radio link control (RLC)/medium access
control (MAC) protocol messages, also referred to as RLC/MAC
control blocks. Examples for such explicit RLC/MAC protocol
messages include Packet Downlink (DL) ACK/NACK or Packet Uplink
(UL) ACK/NACK messages. The RLC/MAC control block is addressed to a
certain radio resource, called a temporary block flow (TBF).
[0006] A TBF is a temporal connection between a mobile station and
a network to support a uni-directional transfer of data. If
supported by the mobile station and the network, more than one (1)
TBF can be allocated to a mobile station. A TBF is temporary and
maintained only for the duration of the data transfer. Each TBF is
assigned a temporary flow identity (TFI) by the network. The TFI is
unique among concurrent TBFs in each direction and is used instead
of mobile station identity in the RLC/MAC layer. For example, in
GPRS and EGPRS modes of operation, the same TFI is included in
every RLC/MAC header belonging to a particular TBF in order to
allow the intended receiver, (i.e., the wireless transmit/receive
unit (WTRU) or network), to determine the addressee of a received
radio block.
[0007] In order to reduce transmission latencies associated with
the use of an entire RLC/MAC control block, it has been proposed in
GSM/(E)GPRS Release 7 to send the ACK/NACK report for a certain TBF
"piggybacked" onto an RLC/MAC data block by puncturing a number of
bits from the channel-coded data portion of the radio block at no
loss of data. This new field is inserted, when needed, into the
RLC/MAC data block and carries the ACK/NACK report as part of the
radio block referred to as a piggybacked ACK/NACK (PAN) field. The
insertion of PAN is possible, and can be configured, both for the
DL and UL directions. The PAN field, when sent to a WTRU in the DL,
carries ACKs or NACKs for data units or protocol data units (PDUs)
previously sent by the WTRU in the UL direction, and vice versa.
The presence or absence of the PAN field in a radio block is
indicated by the RLC/MAC header, either by a bit or bit field
setting, or by setting other code points depending on the RLC/MAC
header type accordingly, and therefore depends on the EGPRS/EGPRS-2
modulation and coding scheme chosen for the transmission of the
radio block. In the DL direction, the PAN field of an RLC/MAC data
block can possibly be addressed to a WTRU that is not the intended
receiver of the data units (or PDUs) in the radio block.
Alternatively, the PAN field and the data units (or PDUs) of the
radio block can be intended for the same WTRU. Both for DL and UL
directions, the TBF to which the PAN field refers can possibly be
different from the TBF corresponding to the data units (or PDUs) of
the radio block, even if the receiver is the same physical unit
(WTRU, or network).
[0008] The actual bit field(s) carrying the ACKs or NACKs in the
PAN field can be encoded according to different procedures, for
example using a starting sequence number (SSN)-based approach or a
time-based approach.
[0009] Since the PAN field is included in a data block that may be
addressed to a different TBF, it is necessary to identify to which
TBF the PAN field is addressed. In addition, a need for additional
methods for PAN transmission and reception modes arises from
additional operation scenarios in GSM/(E)GPRS networks. For
example, identification of the TBF to which the PAN is addressed
should also be possible in the case of multiple TBFs assigned to
one (1) receiver, such as one WTRU. This mode of operation is
needed to facilitate multiple TBFs mode of operation with FANR.
[0010] PAN transmissions may be made for special cases, such as
when a PAN field not actually addressed to a TBF is sent. This mode
of operation is needed to facilitate transmission and reception of
a PAN field not pertaining to data units (or PDUs) and their
associated TFI(s). PAN transmissions may also be made where a PAN
is to be addressed and to be reliably decoded by more than one
receiver. For example, this mode of operation is needed when the
PAN is sent to a group of receivers. Therefore, methods are sought
after that allow for such modes of operation.
SUMMARY
[0011] Methods and apparatus are described. A wireless
transmit/receive unit (WTRU) generates a piggybacked
acknowledgement/non-acknowledgement (PAN) field and a PAN check
sequence (PCS) from the PAN field. The WTRU masks the PCS with a
temporary flow identity (TFI) that includes a specific sequence of
a plurality of bit values that represents information other than an
identification of a particular TBF. The WTRU transmits data that
includes the PAN field and the masked PCS.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] A more detailed understanding may be had from the following
description, given by way of example in conjunction with the
accompanying drawings wherein:
[0013] FIG. 1 shows an example radio block;
[0014] FIG. 2 is an example block diagram of a transmitting
station;
[0015] FIG. 3 is an example block diagram of a receiving station;
and
[0016] FIG. 4 shows an example block diagram of a receiving station
in accordance with another embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0017] When referred to hereafter, the terminology "WTRU" includes
but is not limited to a user equipment (UE), a mobile station, a
fixed or mobile subscriber unit, a pager, a cellular telephone, a
personal digital assistant (PDA), a computer, or any other type of
user device capable of operating in a wireless environment. When
referred to hereafter, the terminology "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.
[0018] Embodiments disclosed herein are applicable to any wireless
communication system including GERAN evolution, etc.
[0019] FIG. 1 shows an example radio block 100. The radio block 100
for data transfer includes one RLC/MAC header 102, a header check
sequence (HCS) 104, one or more RLC data block(s) 106, a block
check sequence (BCS) 108, a PAN field 110, and a PCS 112. The
RLC/MAC header 102, the RLC data block(s) 106 and the PAN field 110
are coded separately for error detection and correction, and a
separate checksum, (e.g., a cyclic redundancy check (CRC)
checksum), is attached to each of them. The RLC/MAC header 102
contains a control field indicating whether a PAN field 110 is
included or not in the radio block 100. The HCS 104 is used for
error detection of the RLC/MAC header 102. The BCS 108 is used for
error detection of the RLC data block 106. A separate BCS may be
included for each RLC data block. The PAN field 110 contains
piggy-backed ACK/NACK information sent in one direction to provide
acknowledgement for a TBF in the other direction. The PCS 112 is
used for error detection and for receiver identification of the PAN
field 110.
[0020] Since the PAN field is included in a data block that may be
addressed to a different TBF, it is necessary to identify to which
TBF the PAN field is addressed. One of the methods is generating a
PCS which is a function of the PAN information bits and masking the
PCS with a TFI value using an exclusive OR (XOR) operation. A
transmitting station performs XOR operation of the calculated PCS
with the TFI. A receiving station first calculates a PCS and
performs XOR operation of the calculated PCS with its own TFI in
order to make sure that the PAN field is addressed to it. An
advantage of this technique is that the transmitter does not need
to send TFI bits explicitly in the PAN field. Unlike the TFI of the
intended receiving station of the radio block, which is explicitly
included in the RLC/MAC header, the PCS is decoded by implicit
knowledge of the TFI during the decoding process by the receiving
station.
[0021] Without loss of generality, the TFI associated with a
particular TBF that is used for addressing the intended receiving
station of an RLC/MAC data or control block may be N1=5 bits long.
Similarly, the TFI for the PAN field may also be N2=5 bits long.
The PCS may be N3=10 bits long. As is obvious to someone skilled in
the art, other choices for N1, N2 and N3 are possible, and the
embodiments disclosed herein may equally be applied. If the N2 TFI
bits are shorter than the PCS length, the TFI may be mixed only
with the first or last N2 bits of the PCS. Alternatively, the N2
TFI bits may be mixed with a selected subset of N2 bits chosen
amongst the N3 PCS bits, where N2<N3. For example, a subset of
five (5) PCS bits b1, b5, b6, b9, b10 may be chosen amongst the
available ten (10) PCS bits, b1, b2, . . . , b9, b10.
[0022] However, this approach has a disadvantage that, if two TFIs,
(one used by the transmitting side and one used by the receiving
side), are close to one another, (e.g., differ only in one bit
value), there is an increased chance of mistaken acceptance. To
overcome this problem, the N2 bits TFI, (e.g., N2=5 TFI), may first
be mapped into an N bits sequence, and then masked, (i.e., XOR
operation), with the PCS. N may be same as the length of the PCS.
Alternatively, N may be chosen to be smaller than the PCS
length.
[0023] FIG. 2 is an example block diagram of a transmitting station
200. The transmitting station 200 may be a WTRU, a Node-B, or any
other apparatus or device. The transmitting station 200 includes a
PCS generator 202, a sequence generator 204, a masking unit 206,
and a transceiver 208. A PAN field is input into the PCS generator
202. The PCS generator 202 generates a PCS based on the PAN field
201. For example, the PCS generator 202 may be a cyclic redundancy
check (CRC) encoder and the PCS may be a CRC checksum generated
based on the PAN field. The sequence generator 204 generates an
N-bit sequence from the N2-bit TFI. The masking unit 206 then masks
the PCS with the N-bit sequence. The masking of the PCS bits with
the sequence may be performed by modulo-2 addition, (i.e., an XOR
operation). The transceiver 208 sends a data block including the
PAN field and the masked PCS. With this scheme, a TFI may be
transmitted in a PAN field without using explicit bits to identify
the TBF. Before transmission, a channel coding, (such as forward
error correction (FEC) coding, rate matching, interleaving, or the
like), may be performed.
[0024] The sequence used for making the PCS may be as simple as
using the sequence itself. For example, if the TFI is N2=5 bits and
the PCS is N=11 bits then the prescribed procedure may be simply to
modulo 2 add the first N2 bits of the PCS with the TFI, or the last
N2 bits, or any predefined set of N2 bits within the N bits.
Alternatively, the sequence may be generated in many different ways
that maximize the difference, (i.e., Hamming distance), between
pairs of resultant patterns. For example, assuming that N2=5 and
N=11, the Reed-Muller (16,5) code may be used to generate a 16 bit
sequence from the 5-bit TFI, and the 16 bit sequence may be
truncated to 11 bits. Alternatively, the 5 bit TFI may be put
through a CRC generator to create an 11 bit sequence. The 5 bit TFI
may be put through a convolutional encoder to create an 11 bit
sequence. The 5 bit TFI may be used as an input or an initial state
to a pseudo noise (PN) generator, (such as a linear shift register
sequence), to generate an 11 bit sequence. Alternatively, the 5 bit
TFI may simply be repeated.
[0025] Alternatively, an 11.times.5 mapping table may be used to
map the 5 bit sequence to an 11 bit sequence. The mapping table may
be generated by a computer optimization algorithm. As example
mapping matrix is as follows:
1 0 0 0 1 1 0 0 0 1 0 0 1 0 0 1 0 1 0 0 1 0 0 0 1 0 1 0 0 1 0 1 0 0
0 0 1 1 0 0 0 1 1 0 0 0 0 0 0 1 1 1 1 1 1. ##EQU00001##
[0026] For example, with this mapping matrix, the 5 bit TFI
B={00011} maps into an 11 bit sequence R={00011111001}. This should
result in a minimum Hamming distance of 4 between any pair of 11
bit sequences generated.
[0027] For the case of mapping the 5 bit TFI into 10 bits, the
following (10,5) systematic coding produces minimum distance of
4:
1 0 0 0 0 0 1 1 1 1 0 1 0 0 0 1 0 1 1 1 0 0 1 0 0 1 1 0 1 1 0 0 0 1
0 1 1 1 0 1 0 0 0 0 1 1 1 1 1 0 ##EQU00002##
[0028] The best sequences may be defined as a set of 32 sequences,
(in case that N2=5), that yield the largest minimum distance
between the worst case pair.
[0029] The above scheme may be applied to any mapping where an N2
bit identifier is used to modify an N3 bit CRC, where N2<N3. If
N2 N3, only N3 bits of the identifier may be used to modify the CRC
and the remaining (N3-N2) bits may be sent explicitly.
[0030] FIG. 3 is an example block diagram of a receiving station
300. The receiving station 300 may be a WTRU, a base station, or
any other apparatus or device. The receiving station 300 includes a
transceiver 302, a sequence generator 304, a de-masking unit 306,
and a PCS decoder 308. The transceiver 302 receives a radio block
including a PAN field and a masked PCS. The transceiver 302 outputs
the PAN field and the masked PCS. The sequence generator 304
generates the sequence from the TFI assigned to the receiving
station 300. The de-masking unit 306 de-masks the received masked
PCS with the generated sequence. The de-masking unit 306 outputs
PAN bits and de-masked PCS bits. The PCS decoder 308 then computes
a PCS, (e.g., CRC bits), based on the received PAN field and
compares the computed PCS with the de-masked received PCS. If the
two PCSs agree, then the received PAN field is declared to be
addressed to the receiving station 300. If the two PCSs do not
agree, the PAN field is declared to be not addressed to the
receiving station 300 and may be discarded.
[0031] Alternatively, the receive processing may be performed in a
different way that is mathematically identical to the procedure
above. FIG. 4 shows a receiving station 400 in accordance with this
alternative. A transceiver 402 receives a radio block including a
PAN field and a masked PCS. The transceiver 402 outputs the PAN
field and the masked PCS. A sequence generator 404 generates the
sequence from the TFI assigned to the receiving station 400. A PCS
encoder 406 computes a PCS, (e.g., CRC bits), based on the received
PAN field. A masking unit 408 masks the computed PCS with the
generated sequence. A comparator 410 then compares the received PCS
bits with the regenerated and masked PCS bits. If the two PCSs
agree, then the received PAN field is declared to be addressed to
the receiving station 400. If the two PCSs do not agree, the PAN
field is declared to be not addressed to the receiving station 400
and may be discarded.
[0032] As an alternative embodiment, a rule-based scheme may be
implemented between a transmitting station and a receiving station
that determines which possible candidate TFI(s) can be used to
compute the PCS depending on the occurrence of predetermined
conditions. The determination which possible candidate TFI(s) can
be used on either one or more occurrences of the PAN field may
result in a restriction to either one (1) possible candidate TFI
value, or to more than one TFI value but still less than a number
of overall possible TFI values. Different conditions to limit or
determine the possible TFI values are possible. For example, a
dependence on frame numbers or timers or equivalent measures of
timing in the GSM system, a dependence of previous events such as
types of received radio blocks or signals, a dependence on other
identifiers to be decoded in conjunction with the first identifier,
etc. may be used.
[0033] A transmitting station and a receiving station may make a
pre-agreement on which TFI that may be transmitted at any given
time instant (i.e., in a particular downlink radio block). When a
receiving station needs to test a received PAN field against more
than one allocated TFI values, the receiving station determines a
particular TFI to be tested at the given time instant based on the
pre-agreed rule. For example, assuming that a receiving station has
two allocated TBFs that result in two differently masked CRC
values, the transmitting station and the receiving station may
agree to employ TFI #1 in even-numbered radio frames, and TFI #2 in
odd-numbered radio frames. Instead of testing against both
TFI-masked CRC hypotheses per received PAN field, the receiving
station may test with only one TFI value. This scheme may be
extended for more than one TBF in a straightforward manner.
[0034] In accordance with another embodiment, the TBF number,
(i.e., TFI), indicated through the PCS may be made dependent on
another secondary identifier in the RLC/MAC data block. A
transmitting station sends a radio block including the PAN field,
the masked PCS, and a secondary identifier. The secondary
identifier indicates a TBF to which the PAN field is addressed so
that the receiving station needs to check only one TFI. For
example, the secondary identifier may be placed into the RLC/MAC
header to indicate that the intended receiver of the PAN is the
same as the addressee of the data units (or PDUs) indicated by the
TFI of the RLC/MAC header.
[0035] The receiving station first checks the secondary identifier
when it is determined that the received radio block includes a PAN
field to determine which TFI that the receiving station needs to
check based on the secondary identifier. With this scheme, the
receiving station needs to perform only one CRC test rather than
multiple tests against all TFIs assigned to the receiving station.
The secondary identifier may be an identifier used between the
transmitting station and other receiving stations. For example, TFI
m may only occur if a certain RLC/MAC header field or a PAN field
is present in the RLC/MAC data block.
[0036] In accordance with another embodiment, a special or reserved
value that represents all admissible TBFs allocated to a particular
receiving station may be used to indicate to the receiving station
the existence of a PAN field addressed to the receiving station. A
transmitting station sends a radio block including a PAN field, a
masked PCS derived using a special or reserved value, and a
secondary identifier. The special or reserved value represents all
TBFs assigned to the receiving station. The secondary identifier
indicates a TBF to which the PAN field is addressed. The special
value may be masked with the PCS. The secondary bit field may be a
part of the header of the data block.
[0037] The receiving station receives a radio block including a PAN
field and a masked PCS and detects the special or reserved value.
Upon detection of the special value, the receiving station
recognizes that the received radio block includes a PAN field
addressed to the receiving station since the special value
represents all TBFs assigned to the receiving station. The
receiving station detects a secondary identifier indicating a TBF
to which the PAN field is addressed. The receiving station then
performs PCS decoding with the selected TFI based on the secondary
identifier.
[0038] In accordance with still another embodiment, a special or
reserved identifier value may be used on the PAN field to mask the
PCS to indicate an action affecting a receiving station listening
to a radio block, or it may be used to simplify PAN encoder and
decoder operation. This scheme may be used either alone or in
conjunction with any embodiments described above.
[0039] In a first example, a special or reserved identifier value
is employed to mask the PCS when the PAN field included in the
radio block and the special or reserved identifier value is used
for control purposes. For example, this special or reserved value
indicated through the PCS may indicate reset of certain positive
acknowledgement (ACK) windows, or it may indicate information
pertaining to RLC/MAC protocol information, such as transmit and
receive state arrays V(A), V(B), or similar.
[0040] In a second example, a special or reserved identifier value
is employed to mask the PCS when the received PAN is to be decoded
by more than one receiving station, (such as in the case of
time-based PAN encoding), and where the payload of the PAN contains
information possibly pertaining to more than one (1) receiving
station.
[0041] In a third example, a special or reserved identifier value
is used to mask the PCS in order to simplify decoding at the
receiving station, such as when the occurrence of the PAN and its
association with data units (or PDUs) of a TBF is un-ambiguously
tied to or determined from context by the intended receiver. For
example, the special or reserved value may be used in the UL when
transmitting to the network, because a single WTRU is usually
un-ambiguously associated with a transmission opportunity in the UL
timeslots through the uplink state flag (USF) assignment procedure
under control by the network and when a WTRU is not assigned more
than one (1) TBF in the UL.
[0042] More than one special or reserved value may be used in the
system. The receiving station (WTRU or network) may implement a
procedure where decoding of received PANs is configured in a
flexible manner, depending on received system setup or
configuration messages. In one case, the receiving station may
decode the PAN against either one (1) or more special or reserved
identifiers only. In another case, the receiving station may decode
the PAN against one (1) or more assigned TFI(s) only. In yet
another case, the receiving station may decode the PAN against
either one or more special or reserved values while simultaneously
attempting to decode against one or more assigned TFIs.
[0043] The special or reserved value may be a reserved TBF code,
e.g. TFI value. For example, all bits of the TFI used to mask the
PCS generated from the PAN field may be set to `0s` in order to
indicate the special or reserved value. As is obvious to one
skilled in the art, other possible choices than an all-zero
sequence are equally possible and equivalent, as long as there is
no other TFI value assigned to a TBF on at least the assigned set
of resources (PDCH(s), or timeslot(s), or WTRUs, or receiver(s)).
Alternatively, the special or reserved value to mask the PCS on the
PAN field may always be the same, either in the GSM/(E)GPRS system,
a group of cells, a cell, set of resources (PDCH), or it may be
assigned on a semi-static basic, such as signaling or configuration
and set-up messages to either one or more receiving stations.
[0044] Alternatively, the special or reserved value may be realized
as another separate PAN field entry or as a bit or bit field or as
a code point of any entry in an RLC/MAC data or control block. For
example, the special or reserved value may be an entry in the
RLC/MAC header, or it may be a bit set in the PAN field.
[0045] Upon detection of the special or reserved value, the
receiving station(s) may perform an action indicated by the special
value. One example for such action is to decode and process the PAN
field according to rules specific to the context of the use of the
special or reserved value, like decoding of the PAN field according
to the bitmap in interpretation of time-based PAN encoding.
Alternatively, the special or reserved value is employed to
simplify the PAN encoding and/or decoding procedure for the PCS in
the transmitting stations and/or receiving stations in order to
avoid implementation of more than one PAN processing units or
constituting components thereof. For example, when a first
implementation sequence is used to mask the PCS with a regular
assigned TFI (corresponding to an assigned TBF), and a second
implementation sequence is used to mask the PCS in the case of no
TFI associated with the PAN transmission and its contents. Using
such a special or reserved value to mask the PCS for the second
implementation sequence makes it possible to employ the first
implementation sequence even in the case of no TFI associated with
the PAN. In the latter case, using the sequence of bits set to `0`
for the masking TFI, the computed PCS corresponds to the
constituting CRC. Even in the case where the special or reserved
identifier is a different sequence, implementation of the second
implementation sequence is still not required, because a simple bit
reversal procedure can be used to align it with the first
implementation sequence.
[0046] 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).
[0047] 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.
[0048] 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.
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