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Software Patent Abstract
An apparatus, method, and software product are for masking a subframe
of a shared control channel. A first part of the subframe is masked
in a way specific to a user equipment, while using an identification
of the user equipment. A remaining part of the subframe is masked
using a second level masking operation, or at least using one other
identification of the user equipment. This allows addition of more
signaling information on an existing shared control channel, for
example in the context of high speed downlink packet access.
Software Patent Claims
1. A method comprising:masking a first part of a subframe of a shared
control channel, in a first masking operation that is specific to
a user equipment, using a first identification of the user equipment;
andusing a second level masking operation, or at least one other
identification of the user equipment, for masking at least a portion
of a remaining part of the subframe.
2. The method of claim 1,wherein the first identification is a
predetermined identification of the user equipment, andwherein the
at least one other identification includes multiple identifications
of the user equipment that are different from the first identification.
3. The method of claim 1,wherein the at least one other identification
of the user equipment consists of a single identification; andwherein
the first identification and the single identification are independently
selectable from a plurality of possible identifications of the user
equipment.
4. The method of claim 1, wherein the portion of the remaining
part of the subframe includes a redundancy check.
5. The method of claim 1, wherein the subframe comprises three
slots, the first part of the subframe comprises one of the three
slots, and the remaining part of the subframe comprises another
two of the three slots.
6. The method of claim 1, further comprising mapping a first set
of bits to the first part of the subframe, and mapping a second
distinct set of bits to the remaining part of the subframe.
7. The method of claim 3, wherein the number of possible identifications
squared is how many combinations are possible of the first identification
and the single identification.
8. An apparatus comprising:means for masking a first part of a
subframe of a shared control channel, in a first masking operation
that is specific to a user equipment, using a first identification
of the user equipment; andmeans for using a second level masking
operation, or at least one other identification of the user equipment,
for masking at least a portion of a remaining part of the subframe.
9. The apparatus of claim 8,wherein the first identification is
a predetermined identification of the user equipment, andwherein
the at least one other identification includes multiple identifications
of the user equipment that are different from the first identification.
10. The apparatus of claim 8,wherein the at least one other identification
of the user equipment consists of a single identification; andwherein
the first identification and the single identification are independently
selectable from a plurality of possible identifications of the user
equipment.
11. An apparatus comprising:a first masking module configured to
mask a first part of a subframe of a shared control channel, in
a first masking operation that is specific to a user equipment,
using a first identification of the user equipment; anda second
masking module, configured to use a second level masking operation,
or at least one other identification of the user equipment, to mask
at least a portion of a remaining part of the subframe.
12. The apparatus of claim 11,wherein the first identification
is a predetermined identification of the user equipment, andwherein
the at least one other identification includes multiple identifications
of the user equipment that are different from the first identification.
13. The apparatus of claim 11,wherein the at least one other identification
of the user equipment consists of a single identification; andwherein
the first identification and the single identification are independently
selectable from a plurality of possible identifications of the user
equipment.
14. The apparatus of claim 11, wherein the portion of the remaining
part of the subframe includes a redundancy check.
15. The apparatus of claim 11, wherein the subframe comprises three
slots, the first part of the subframe comprises one of the three
slots, and the remaining part of the subframe comprises another
two of the three slots.
16. The apparatus of claim 11, further comprising mapping a first
set of bits to the first part of the subframe, and mapping a second
distinct set of bits to the remaining part of the subframe.
17. The apparatus of claim 13, wherein the number of possible identifications
squared is how many combinations are possible of the first identification
and the single identification.
18. A computer program product including a computer-readable medium
having computer-executable components comprising:a component for
masking a first part of a subframe of a shared control channel,
in a first masking operation that is specific to a user equipment,
using a first identification of the user equipment; anda component
for using a second level masking operation, or at least one other
identification of the user equipment, for masking at least a portion
of a remaining part of the subframe.
19. The computer program product of claim 18,wherein the first
identification is a predetermined identification of the user equipment,
andwherein the at least one other identification includes multiple
identifications of the user equipment that are different from the
first identification.
20. The computer program product of claim 18,wherein the at least
one other identification of the user equipment consists of a single
identification; andwherein the first identification and the single
identification are independently selectable from a plurality of
possible identifications of the user equipment.
Software Patent Description
BACKGROUND OF THE INVENTION
[0001]1. Technical Field
[0002]The present invention pertains to the field of telecommunications.
More particularly, the present invention pertains to transmission
of packet data.
[0003]2. Discussion of Related Art
[0004]It is well known in the art that the Universal Mobile Telephony
System (UMTS) Terrestrial Radio Access (UTRA) can accommodate Frequency
Division Duplex (FDD), for example using Wideband Code Division
Multiple Access (WCDMA). Downlink packet data transmission in UTRA
FDD (WCDMA) is a feature that is included in Release 5 specifications
of the Third Generation Partnership Project (3GPP), including the
specifications for High Speed Downlink Packet Access (HSDPA). For
general background about HSDPA, a good resource is the book WCDMA,
Requirements and Practical Design by Rudolf Tanner and Jason Woodard
(c. 2004). Sections 12.1 and 12.2 are especially useful (i.e. pages
335-358), and those two sections are incorporated herein by reference.
[0005]Downlink packet data transmission in UTRA FDD (WCDMA) is
further enhanced in Release 6 of 3GPP, with the support of a Fractional
Dedicated Physical Channel (F-DPCH) and the support of signaling
radio bearer (SRB) mapping on the High Speed Downlink Shared Channel
(HS-DSCH).
[0006]A terminal faces a problem dealing with modified signaling.
If the signaling on the High Speed Shared Control Channel (HS-SCCH)
is totally rewritten and new bits added, then the overhead increases.
Due to the fact that the signaling on the HS-SSCH is based on the
user identification, the quick solutions mentioned in some papers--or
used with High Speed Uplink Packet Access (HSUPA) Enhanced Dedicated
Absolute Grant Channel (E-AGCH)--would be to simply allocate multiple
identifiers for one terminal. Such quick solutions, however, cause
the problem of the terminal having to run several parallel decodings,
because one must listen to four different HS-SCCHs in Release 6,
and decide based on the decoder matrix for the first part which
HS-SCCH to completely decode. This is because there is no Cyclic
Redundancy Check (CRC) in the first part of HS-SCCH, and instead
identification needs to be done by comparing the Viterbi matrix
of all 4 HS-SCCHs.
[0007]One prior art solution is to use an additional identification
(ID) for masking the new information. This, however, can result
in doubling the number of decoder matrix comparisons from four to
eight, with potential impact upon reliability as well. If more than
just one additional bit is desired--for example, for the purpose
of Multiple Input Multiple Output (MIMO) antenna phase information--then
the complexity difference would only increase.
[0008]HS-SCCH structure and UE-ID usage are described in prior
art standards. See, for example, 3GPP TS25.211 V.7.0.0 (2006-03),
Physical channels and mapping of transport channels onto physical
channels (FDD) (Release 7) which is incorporated by reference herein.
TS25.211 discloses that the HS-SCCH has a fixed rate (60 kbps, SF=128)
downlink physical channel which is used to carry downlink signaling
related to HS-DSCH transmission. The sub-frame structure of the
HS-SCCH is detailed in TS25.211.
[0009]Also incorporated by reference herein is 3GPP TS25.212 V.7.0.0
(2006-03), Multiplexing and channel coding (FDD) (Release 7), which
discloses that physical channel mapping maps bits S1 to a first
slot of the HS-SCCH sub-frame, after user equipment (UE) specific
masking. This UE-specific masking is done using the UE-ID as described
in chapter 4.6.7 of TS25.212. The physical channel mapping maps
bits R2 to the second and third slots of the HS-SCCH sub-frame.
These bits consist of a CRC (which is a kind of a check-sum) that
is masked with the same UE-id, using the same method. Thus the first
part (i.e. first slot) carries the UE-ID masked on it, and the second
part (i.e. the remaining part consisting of the second and third
slots) carry the UE-ID masked on the 16-bit CRC.
[0010]Unfortunately, these prior art technical specifications do
not suggest any way to solve the problems that a UE faces when dealing
with modified signaling. They do not solve the problem of the terminal
having to run several parallel decodings. Various proposed Release
7 HSDPA improvements aim to use a modified version of the existing
HSDPA signaling, but there remains the problem of the terminal having
to run several parallel decodings.
DISCLOSURE OF THE INVENTION
[0011]The present invention addresses signaling related to various
proposed Release 7 HSDPA improvements which aim to use a modified
version of the existing HSDPA signaling. Such proposals are related
to either HSDPA cell change, uplink gating, downlink discontinuous
reception (DRX) and HSDPA multiple input multiple output (MIMO).
[0012]The present invention includes a method for adding more signaling
information on the existing HS-SCCH channel of the HSDPA. A second
level masking operation and/or secondary UE IDs can be used for
the second part of the HS-SCCH only. Alternatively, independent
masking operations and/or UE IDs can be used for the first part
and the second part of the HS-SCCH.
[0013]According to an embodiment of the invention, a first part
of the subframe is masked in a manner specific to the UE, while
using an identification of the UE. A remaining part of the subframe
is masked using a second level masking operation, or at least using
one other identification of the user equipment. This allows addition
of more signaling information on the existing HS-SCCH.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014]FIG. 1 is a flow chart illustrating a method according to
an embodiment of the present invention.
[0015]FIG. 2 is a block diagram illustrating and apparatus according
to an embodiment of the present invention.
[0016]FIG. 3 is a flow chart illustrating various aspects of a
coding chain according to an embodiment of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0017]An embodiment of the present invention will now be detailed
with the aid of the accompanying figures. It is to be understood
that this embodiment is merely an illustration of one particular
implementation of the invention, without in any way foreclosing
other embodiments and implementations.
[0018]A first embodiment of the invention is to use an additional
second level masking operation (or alternative new terminal specific
UE ID) for the second part of the HS-SCCH only, thus allowing the
terminal initially to narrow down to the single HS-SCCH and then
to check whether the CRC would go correctly with an additional masking
sequence instead. This makes it possible to either only carry a
new bit of information in the existence of a new masking sequence
(such as an indication of the last packet for the terminal) or to
have even more alternative masking sequences available to convey
other issues, e.g. MIMO antenna weights as part of the signaling
space.
[0019]Instead of the second level masking operation a modulo sum
operation (i.e. a summation that if exceeding the maximum value
results with the sum minus the maximum value) could be used as well.
[0020]In another embodiment of the invention, if the added complexity
of introducing multiple UE-IDs to the first part is acceptable then
the first part should be allowed to be masked with one UE-ID and
the CRC of the second part should be allowed to be masked with another
ID or with a second level masking operation. This way, simply by
using different UE-ID combinations, N.sup.2 different messages can
be delivered to the UE. For example, if two UE-IDs would be used,
then the UE could be given 2.times.2=4 different messages without
interfering with the actual structure of the HS-SCCH. This method
could be applied, for example, to signalling HSDPA MIMO antenna
weights in the downlink.
[0021]The invention uses different UE-IDs for the UE-specific masking
of the first part and the UE-specific masking of the CRC in the
second part. A new ID for the second part could be replaced with
the mentioned second level masking operation. Alternative embodiments
can be described as follows: [0022]1. The first part should always
use a single specific UE-ID and the multiple UE-IDs (delivering
additional information to the current HS-SCCH) are only used in
the second part. This simplifies the receiver implementation. [0023]2.
The first and the second part use UE-IDs independently, to enable
N.sup.2 different combinations.
[0024]One useful way of implementing the invention is for the terminal
to listen to the HS-SCCH pool indicated, and detect from the first
part of the HS-SCCH that the data is intended for that device (the
first part of the HS-SCCH has user identification plus codes to
de-spread and modulate), whereupon the terminal proceeds to the
second part and calculates the CRC results based on the two terminal
IDs, and if the new ID (or the second level masking pattern) was
used then that indicates, for example, the end of the packet sequence.
A significant benefit of this being used as part of the packet reception
is the fact that now a base transceiver station (BTS) gets feedback
as to whether the message was actually received (in the form of
ACK/NACK information).
[0025]Another useful way of implementing the invention is as just
described, but allowing the alternative UE-IDs to be used independently
in the two parts. A major benefit of doing so is a larger signaling
space, since, for example, three UE-IDs would provide nine different
messages instead of the three messages possible with the current
structure. Alternatively, with the MIMO case, two HS-SCCHs can be
used, and then the second level masking can be applied on both HS-SCCHs
which the terminal has to receive.
[0026]A further advantage of the invention is that there is no
need to have double HS-SCCH decoding resources, because the simple
exclusive "or" operation (i.e. XOR operation) is used
to test whether an alternative signature was used. The user identification
is part of the CRC attachment process, so basically the use of N
additional signatures can be covered by a CRC calculation that is
N times parallel.
[0027]Because the CRC length is 16 bits, the impact to the signaling
reliability is marginal, given that there exists now N correct outcomes
for the CRC check instead of one as was the case earlier. The only
added extra complexity is to run two or more CRC check operations,
which are rather trivial for practical implementations. If the simplification
is not taken in, then the usage of independent UE-IDs in the two
parts enables an N.sup.2 larger signaling space with the UE-ID usage
than in current approaches.
[0028]Chapter 4.6.4 of TS25.212 describes CRC attachment for HS-SCCH.
From the sequence of bits X.sub.1,1, X.sub.1,2, . . . , X.sub.1,8,
X.sub.2,1, X.sub.2,3, . . . , X.sub.2,13 a 16-bit CRC is calculated.
This gives a sequence of bits C.sub.1, C.sub.2, . . . , C.sub.16
where:
C.sub.k=p.sub.im(17-k) k=1,2, . . . ,16
This sequence of bits is then masked with the UE Identity X.sub.ue,1,
X.sub.ue,2, . . . , X.sub.ue,16 and then appended to the sequence
of bits X.sub.2,1, X.sub.2,2, . . . , X.sub.2,13 to form the sequence
of bits
[0029]Y.sub.1, Y.sub.2, . . . , Y.sub.29, where
Y.sub.i=X.sub.2,i i=1,2, . . . ,13
Y.sub.i=(C.sub.i-13+X.sub.ue,i-13) mod 2i=14,15, . . . ,29
The present invention provides for alternative UE IDs in the UE
Identity X.sub.ue.
[0030]Turning now to the figures, FIG. 1 illustrate a method 100
according to the present invention. A first part of a subframe (of
a shared control channel) is masked 105, using a first identification
of a user equipment. Then, a first set of bits is mapped 110 onto
the first part of the subframe. The remaining part of the subframe
(or at least a portion of it) is masked 115, using a second level
masking operation, or using another identification of the user equipment.
Then, a second distinct set of bits is mapped 120 onto the second
part of the subframe.
[0031]An apparatus 200 for performing the method of FIG. 1 is shown
in FIG. 2. A processor 227 includes a first masking module 210 and
a second masking module 225. The first masking module performs a
masking procedure 215 on a first part of the subframe 220. The second
masking module performs a masking procedure 230 on the remaining
part of the subframe 235. The processor 227 is able to perform these
masking operations by obtaining from the memory 240 a plurality
of user Ids for the user equipment at issue.
[0032]Turning now to FIG. 3, this shows a coding chain 300 for
HS-SCCH. A person skilled in the art will understand that the procedure
on the left-hand-side of FIG. 3 involves masking a first part of
a subframe of the shared control channel HS-SCCH, and the procedure
on the right-hand-side of FIG. 3 involves masking at least a portion
of a remaining part of the subframe. The UE Specific CR Attachment
310 is analogous to the CRC attachment for HS-SCCH, as described
at Chapter 4.6.4 of TS25.212. Unlike in the related art, the present
embodiment of the invention utilizes alternative UE identifications
during the UE-Specific Cyclic Redundancy Attachment 310.
[0033]Of course, the present invention also includes a software
product for performing the embodiment of the method described above,
and the software can be implemented using a general purpose or specific-use
computer system, with standard operating system software conforming
to the method described herein. The software is designed to drive
the operation of the particular hardware of the system, and will
be compatible with other system components and I/O controllers.
The computer system of this embodiment includes a CPU processor
such as the processor 227 shown in FIG. 2, comprising a single processing
unit, multiple processing units capable of parallel operation, or
the CPU can be distributed across one or more processing units in
one or more locations, e.g., on a client and server, or within other
components. The memory 240 shown in FIG. 2 may comprise any known
type of data storage and/or transmission media, including magnetic
media, optical media, random access memory (RAM), read-only memory
(ROM), a data cache, a data object, or the like. Moreover, similarly
to the CPU, the memory 240 may reside at a single physical location,
comprising one or more types of data storage, or be distributed
across a plurality of physical systems in various forms.
[0034]It is to be understood that all of the present figures, and
the accompanying narrative discussions of corresponding embodiments,
do not purport to be completely rigorous treatments of the method,
apparatus, system, and software product under consideration. A person
skilled in the art will understand that the steps and signals of
the present application represent general cause-and-effect relationships
that do not exclude intermediate interactions of various types,
and will further understand that the various steps and structures
described in this application can be implemented by a variety of
different sequences and configurations, using various combinations
of hardware and software which need not be further detailed herein. |