U.S. patent number RE42,692 [Application Number 12/379,600] was granted by the patent office on 2011-09-13 for method for compact representation of multi-code signaling in communication systems.
This patent grant is currently assigned to Nokia Corporation. Invention is credited to Frank Frederiksen, Troels Emil Kolding.
United States Patent |
RE42,692 |
Frederiksen , et
al. |
September 13, 2011 |
Method for compact representation of multi-code signaling in
communication systems
Abstract
A method for compact representation of multi-code signaling that
includes determining a number of multi-codes and a code offset. A
codeword is formulated that includes a code group indicator and an
offset indicator. The codeword represents a compact representation
of multi-code signaling and is formulated and may be decoded
without the need for a look-up table.
Inventors: |
Frederiksen; Frank (Klarup,
DK), Kolding; Troels Emil (Klarup, DK) |
Assignee: |
Nokia Corporation (Espoo,
FI)
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Family
ID: |
26853862 |
Appl.
No.: |
12/379,600 |
Filed: |
February 25, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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60331391 |
Nov 15, 2001 |
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Reissue of: |
10157159 |
May 30, 2002 |
7321576 |
Jan 22, 2008 |
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Current U.S.
Class: |
370/335; 370/441;
455/450 |
Current CPC
Class: |
H04J
13/00 (20130101); H04B 1/707 (20130101); H04B
2201/70705 (20130101); H04J 13/16 (20130101); H04J
13/0077 (20130101) |
Current International
Class: |
H04B
7/216 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Motorola, "HSDPA Signaling Requirements", TSG-RAN Working Group 2,
R2-A1010015, Edinburgh, UK, Jan. 15-19, 2001. cited by other .
Nokia, "HSDPA Related Signaling Parameters in Downlink", Version 2,
TSG-RAN Working Group 2, Meeting #21, XP-002291723, Busan, Korea,
May 21-25, 2001. cited by other .
Samsung Electronics, "DL Signaling for HSDPA", TSG-RAN Working
Group 1, Meeting #21, R1-01-0874, Turin, Italy, Aug. 27-31, 2001.
cited by other .
Nokia, "Compact Signalling of Multi-Code Allocation for HSDPA",
3GPP TSG RAN Working Group 1, Meeting #22, XP 002291721, Jeju,
Korea, Nov. 19-23, 2001. cited by other .
Nokia, "Compact Signalling of Multi-Code Allocation for HSDPA,
Version 2", 3GPP TSG RAN Working Group 1, Meeting #23, XP
002291722, Espoo, Finland, Jan. 8-11, 2002. cited by other .
Qualcomm, "DL Control Structure for HS-PDSCH", 3GPP TSG-RAN Working
Group 1, Meeting #20, XP 002291725, Busan, Korea, May 21-25, 2001.
cited by other .
Motorola, "Associated Signaling Requirements for High Speed DSCH
(HS-DSCH)", TSG-RAN Working Group 1, Meeting #20, XP 002291726,
Busan, Korea, May 21-25, 2001. cited by other .
Ericsson, "Signaling Requirements for HS-DSCH", 3GPP TSG-RAN
Working Group 1, Meeting #20, XP 002291727, Busan, Korea, May
21-25, 2001. cited by other.
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Primary Examiner: Ly; Anh-Vu
Attorney, Agent or Firm: Squire, Sanders & Dempsey,
LLP
Parent Case Text
The present invention claims the benefit of Provisional Patent
application Ser. No. 60/331,391 filed Nov. 15, 2001, the contents
contained therein being incorporated by reference herein in its
entirety.
Claims
What is claimed is:
1. A method to provide compact representation of multi-code
signaling, the method comprising: determining.Iadd., by a device,
.Iaddend.a number of multi-codes; determining.Iadd., by the device,
.Iaddend.a code offset; and formulating.Iadd., by the device,
.Iaddend.a codeword, the codeword comprising a code group indicator
of the determined number of multi-codes and an offset indicator of
the determined code offset, wherein the formulated codeword
comprises a compact representation of multi-code signaling and is
decodable without the need for a look-up table, and wherein the
codeword is used to assign codes and a code offset to mobile
stations.
2. The method according to claim 1, the formulating a codeword
further comprising: determining a first term, the first term
comprising a minimum of the multi-code number and sixteen minus the
multi-code number; determining a first part of the codeword by
subtracting one from the first term, the first part representing
the code group indicator; determining a second term, the second
term equal to zero if seven is larger than or equal to the
multi-code number, the second term equal to one if the multi-code
number is larger than seven; determining a third term by
calculating a fourth term by multiplying the second term by fifteen
and subtracting the fourth term from the code offset minus one;
determining a second part of the codeword by taking an absolute
value of the third term, the second part representing the offset
indicator; and forming the codeword by concatenating the first part
of the codeword with the second part of the codeword.
3. The method according to claim 1, the code group indicator
comprising three bits.
4. The method according to claim 1, the offset indicator comprising
four bits.
5. A method for decoding a multi-code signaling code-word
comprising: identifying a codeword, the codeword comprising a code
group indicator and an offset indicator; determining a number of
multi-codes based on the code group indicator of the codeword; and
determining a code offset from the offset indicator of the
codeword; decoding the codeword by providing the number of
multi-codes and code offset; and determining the number of
multi-codes and corresponding code offset without the need for a
look-up table, and wherein the decoded multi-codes and
corresponding code offset provides multi codes to a mobile
device.
6. The method according to claim 5, the decoding a multi-code
signaling codeword comprising: identifying a first part and a
second part of the codeword; the first part representing the code
group indicator and the second part representing the offset
indicator; calculating a first term, the first term equal to one if
the second part is larger than or equal to the first part
subtracted from fifteen, else the first term is equal to zero;
calculating a second term by multiplying the first term by sixteen;
identifying a number of multi-codes by taking an absolute value of
the first part plus one minus the second term; calculating a third
term, the third term equal to one if the number of multi-codes is
larger than or equal to eight, else the third term is equal to
zero; calculating a fourth term by multiplying the third term by
seventeen; and identifying a code offset by taking an absolute
value of the second part plus one minus the fourth term.
7. The method according to claim 5, the code group indicator
comprising three bits.
8. The method according to claim 5, the offset indicator comprising
four bits.
9. A system for compact representation of multi-code signaling
comprising: a network; a base station connected to the network; a
network device connected to the base station via the network,
wherein the base station determines a number of multi-codes and a
code offset for use by the network device, the base station
encoding the number of multi-codes and code offset into a codeword
comprising a compact representation of multi-code signaling, the
codeword being encoded by the base station and decoded by the
network device without the need for a look-up table.
10. The system according to claim 9, the network comprising a
wireless network.
11. The system according to claim 9, the network device comprising
a wireless device.
12. The system according to claim 11, the wireless device
comprising one of a wireless phone, a portable computer, and a
Personal Digital Assistant (PDA).
13. The system according to claim 9, the base station including an
encoding function, the encoding function performing: determining a
first term, the first term comprising a minimum of the multi-code
number and sixteen minus the multi-code number; determining a first
part of the codeword by subtracting one from the first term, the
first part representing a code group indicator; determining a
second term, the second term equal to zero if seven is larger than
the multi-code number, the second term equal to one if the
multi-code number is larger than seven; determining a third term by
calculating a fourth term by multiplying the second term by fifteen
and subtracting the fourth term from the code offset minus one;
determining a second part of the codeword by taking an absolute
value of the third term, the second part representing a offset
indicator; and forming the codeword by concatenating the first part
of the codeword with the second part of the codeword.
14. The system according to claim 13, the encoding function
comprising at least one of hardware and software.
15. The system according to claim 9, the remote device including a
decoding function, the decoding function performing: identifying a
first part and a second part of the codeword; the first part
representing a code group indicator and the second part
representing an offset indicator; calculating a first term, the
first term equal to one if the second part is larger than or equal
to the first part subtracted from fifteen, else the first term is
equal to zero; calculating a second term by multiplying the first
term by sixteen; identifying a number of multi-codes by taking an
absolute value of the first part plus one minus the second term;
calculating a third term, the third term equal to one if the number
of multi-codes is larger than or equal to eight, else the third
term is equal to zero; calculating a fourth term by multiplying the
third term by seventeen; and identifying a code offset by taking an
absolute value of the second part plus one minus the fourth
term.
16. The system according to claim 15, the decoding function
comprising at least one of hardware and software.
17. A mobile device configured to receive a codeword representing
multi-code signaling, the mobile device .[.configured to.].
.Iadd.comprising.Iaddend.: .Iadd.a processor and a memory, wherein
the processor is configured to .Iaddend. identify a first part and
a second part of the codeword; the first part representing a code
group indicator and the second part representing an offset
indicator; calculate a first term, the first term equal to one if
the second part is larger than or equal to the first part
subtracted from fifteen, else the first term is equal to zero;
calculate a second term by multiplying the first term by sixteen;
determine a number of multi-codes by taking an absolute value of
the first part plus one minus the second term; calculate a third
term, the third term equal to one if the number of multi-codes is
larger than or equal to eight, else the third term is equal to
zero; calculate a fourth term by multiplying the third term by
seventeen; and determine a code offset by taking an absolute value
of the second part plus one minus the fourth term, wherein the
codeword is used to assign codes and a code offset to mobile
stations.
18. A method to provide representation of multi-code signaling
comprising: allocating.Iadd., by a device, .Iaddend.a number of
multi-codes (M) and a code offset (P); and formulating.Iadd., by
the device, .Iaddend.a codeword, the codeword comprising a code
group indicator indicating the number of multi-codes and an offset
indicator indicating the code offset, the code group indicator
equal to the minimum of M-1 and 15-M, the offset indicator being
equal to the absolute value of P-1-((M/8 rounded to the nearest
lower integer) multiplied by 15), wherein the codeword comprises
seven bits, wherein the codeword is used to assign codes and a code
offset to mobile stations.
19. The method according to claim 18, further comprising sending
the codeword on a High Speed Shared Control Channel (HS-SCCH).
20. The method according to claim 18, further comprising
formulating the codeword without the need for a look-up table.
21. A system for compact representation of multi-code signaling
comprising: a network; a base station connected to the network; a
network device connected to the base station via the network,
wherein the base station determines a number of multi-codes and a
code offset for use by the network device, the base station
encoding the number of multi-codes and code offset into a codeword
comprising a compact representation of multi-code signaling,
wherein the codeword is decodable without the need of a look-up,
table, and the codeword is used to assign codes and a time offset
to the network device.
22. The system according to claim 21, the base station including an
encoding function, the encoding function performing: allocating a
number of multi-codes (M) and a code offset (P); and formulating a
codeword, the codeword comprising a code group indicator and an
offset indicator, the code group indicator equal to the minimum of
M-1 and 15-M, the offset indicator being equal to the absolute
value of P-1-((M/8 rounded to the nearest lower integer) multiplied
by 15), wherein the codeword comprises seven bits.
23. A base station configured to provide representation of
multi-code signaling, the base station comprising: an allocation
unit configured to allocate a number of multi-codes (M) and a code
offset (P); and a formulation unit configured to formulate a
codeword, the codeword comprising a code group indicator indicating
the number of multi-codes and an offset indicator indicating the
code offset, the code group indicator equal to the minimum of M-1
and 15-M, the offset indicator being equal to the absolute value of
P-1-((M/8 rounded to the nearest lower integer) multiplied by 15),
wherein the codeword comprises seven bits, wherein the codeword is
used to assign codes and a time offset to mobile stations.
24. A network node to provide compact representation of multi-code
signaling, the network node .[.configured to.].
.Iadd.comprising.Iaddend.: .Iadd.a processor and a memory, wherein
the processor is configured to .Iaddend. determine a number of
multi-codes; determine a code offset; and formulate a codeword, the
codeword comprising a code group indicator of the determined number
of multi-codes and an offset indicator of the determined code
offset, wherein the formulated codeword comprises a compact
representation of multi-code signaling and decoded without the need
for a look-up table, wherein the codeword is used to assign codes
and a time offset to mobile stations.
25. A network node to provide representation of multi-code
signaling, the network node comprising: an allocation unit
configured to allocate a number of multi-codes (M) and a code
offset (P); and a formulation unit configured to formulate a
codeword, the codeword comprising a code group indicator indicating
the number of multi-codes and an offset indicator indicating the
code offset, the code group indicator equal to the minimum of M-1
and 15-M, the offset indicator being equal to the absolute value of
P-1-((M/8 rounded to the nearest lower integer) multiplied by 15),
wherein the codeword comprises seven bits, wherein the codeword is
used to assign codes and a code offset to mobile stations.
.Iadd.26. A network node, comprising: a processor; and a memory,
wherein the processor is configured to determine a number of
multi-codes, determine a code offset, and formulate a codeword, the
codeword comprising a code group indicator and an offset indicator,
wherein the codeword comprises a compact representation of
multi-code signaling and is formulated and decoded without the need
for a look-up table. .Iaddend.
.Iadd.27. The network node according to claim 26, wherein the
network node comprises a base station or a radio network
controller. .Iaddend.
.Iadd.28. A mobile device comprising: a processor and a memory,
wherein the processor is configured to identify a codeword in
communication from a network node; identify a code group indicator
and an offset indicator from the codeword; and determine a number
of multi-codes M and a code offset P from the code group indicator
and the offset indicator wherein M and P are integers, wherein the
code group indicator is equal to the minimum of M-1 and 15-M, the
offset indicator is equal to the absolute value of P-1-((M/8
rounded to the nearest lower integer) multiplied by 15), wherein
the codeword comprises seven bits. .Iaddend.
.Iadd.29. The mobile device according to claim 28, wherein the
processor is further configured to receive the codeword on a High
Speed Shared Control Channel (HS-SCCH). .Iaddend.
.Iadd.30. The mobile device according to claim 28, wherein the
processor is further configured to decode the codeword without a
need for a look-up table. .Iaddend.
.Iadd.31. A system, comprising: a network node; and a network
device operably connected to the network node, wherein the network
node is configured to determine a number of multi-codes, determine
a code offset, and formulate a codeword, the codeword comprising a
code group indicator and an offset indicator, wherein the codeword
comprises a compact representation of multi-code signaling and is
formulated and decoded without the need for a look-up table.
.Iaddend.
.Iadd.32. A network node, comprising: a processor; and a memory,
wherein the processor is configured to allocate a number of
multi-codes M and a code offset P wherein M and P are integers; and
formulate a codeword, the codeword comprising a code group
indicator and an offset indicator, the code group indicator equal
to the minimum of M-1 and 15-M, the offset indicator being equal to
the absolute value of P-1-((M/8 rounded to the nearest lower
integer) multiplied by 15), wherein the codeword comprises seven
bits. .Iaddend.
.Iadd.33. The network node according to claim 32, wherein the
network node comprises a base station or a radio network
controller. .Iaddend.
.Iadd.34. A system, comprising: a network node; and a network
device operably connected to the network node, wherein the network
node is configured to allocate a number of multi-codes M and a code
offset P wherein M and P are integers; and formulate a codeword,
the codeword comprising a code group indicator and an offset
indicator, the code group indicator equal to the minimum of M-1 and
15-M, the offset indicator being equal to the absolute value of
P-1-((M/8 rounded to the nearest lower integer) multiplied by 15),
wherein the codeword comprises seven bits. .Iaddend.
.Iadd.35. An apparatus, comprising: a processor and a memory,
wherein the processor is configured to identify a first part and a
second part of a codeword, the first part representing a code group
indicator and the second part representing an offset indicator;
calculate a first term, the first term equal to one if the second
part is larger than or equal to the first part subtracted from
fifteen, else the first term is equal to zero; calculate a second
term by multiplying the first term by sixteen; identify a number of
multi-codes by taking an absolute value of the first part plus one
minus the second term; calculate a third term, the third term equal
to one if the number of multi-codes is larger than or equal to
eight, else the third term is equal to zero; calculate a fourth
term by multiplying the third term by seventeen; and identify a
code offset by taking an absolute value of the second part plus one
minus the fourth term. .Iaddend.
Description
BACKGROUND
1. Field of the Invention
This invention relates to multi-code signaling, and more
specifically to compact representation of multi-code signaling in
communication systems.
2. Discussion of the Related Art
For some communication systems, WCDMA (Wideband Code Division
Multiple Access) is used as the access technique. In order to
improve the data rate for a single user, this user may be allowed
to utilize several spreading codes (multi-code operation). One
specific area, where this multi-code operation is utilized is in
HSDPA (High Speed Downlink Packet Access), where the user's
spreading factor is set to the fixed number of 16.
For HSDPA, a base station needs to signal to the mobile node or
user equipment (UE) exactly how many multi-codes have been
allocated and at which offset the set of codes begin (all defined
at spreading factor 16 level). It is assumed that only clusters of
consecutive codes are allocated to one user at a time.
In general, up to 15 multi-codes may be supported by the most
capable UEs and for the single-code case there is up to 15
different code offsets possible since a single code (offset 0) is
reserved to the common channels P-CPICH/P-CCPCH. Commonly, 4 bits
are used in order to represent number of multi-codes and 4 bits are
used in order to represent the code tree offset. Hence, altogether
2.times.4=8 bits are needed to make full-flexibility signaling.
Some have proposed that only a subset of multi-code allocations
should be allowed thereby enabling a representation by fewer bits,
e.g., down to 5 bits. However, since more flexibility with respect
to multi-code utilization leads to a better spectral efficiency as
well as higher RRM flexibility (QoS, code/time multiplexing), it is
desirable to only limit the possible multi-code set as little as
possible; preferably not at all.
Some combinations of multi-code number and code offsets are not
possible. For example, if 15 multi-codes are allocated to a user
there is only one possible offset combination. In total there is
only 120 combinations. By building a lookup table with the possible
combinations, 120 combinations can be represented using 7 bits.
However, the major drawback of the lookup table method is that it
requires additional memory at the UE side to decode the received
information.
Some have also proposed that instead of indicating the starting
position and the number of codes, that the code assignment
information is only reported among the possible combinations of
code allocation as an alternative means of preserving full
flexibility while reducing the number of bits. However, this method
leads to conditioned signaling which should be avoided when
possible.
It has also been suggested to reduce the number of possible
multi-codes such that for instance 1, 5, 10 and 15 multi-codes are
the only options that are available. This solution will require 6
bits for the signaling, but at the cost of less flexibility in the
code allocation.
Therefore a need exists for reducing the signaling overhead using
bit-efficient ways of signaling while maintaining performance and
flexibility.
SUMMARY OF THE INVENTION
The present invention relates to a method for compact
representation of multi-code signaling that includes: determining a
number of multi-codes, determining a code offset, and formulating a
codeword that includes a code group indicator and an offset
indicator. The codeword represents a compact representation of
multi-code signaling and is formulated and may be decoded without
the need for a look-up table.
The formulating a codeword may include: determining a first term
where the first term is a minimum of the multi-code number and
sixteen minus the multi-code number; determining a first part of a
codeword by subtracting one from the first term where the first
part represents the code group indicator; determining a second term
where the second term is equal to zero if seven is larger than or
equal to the multi-code number or equal to one if the multi-code
number is larger than seven; determining a third term by
calculating a fourth term by multiplying the second term by fifteen
and subtracting the fourth term from the code offset minus one;
determining a second part of the codeword by taking an absolute
value of the third term where the second part represents the offset
indicator; and forming the codeword by concatenating the first part
of the codeword with the second part of the codeword.
Moreover, the present invention relates to a method for decoding a
multi-code signaling codeword that includes: identifying a codeword
where the codeword includes a code group indicator and an offset
indicator; determining a number of multi-codes from the codeword;
and determining a code offset from the codeword. The number
multi-codes and corresponding code offset may be determined without
the need for a look-up table.
The decoding a multi-code signaling codeword may include:
identifying a first part and a second part of a codeword where the
first part represents the code group indicator and the second part
represents the offset indicator; calculating a first term, the
first term equal to one if the second part is larger than or equal
to the first part subtracted from fifteen, else the first term is
equal to zero; calculating a second term by multiplying the first
term by sixteen; identifying a number of multi-codes by taking an
absolute value of the first part plus one minus the second term;
calculating a third term, the third term equal to one if the number
of multi-codes is larger than or equal to eight, else the third
term is equal to zero; calculating a fourth term by multiplying the
third term by seventeen; and identifying a code offset by taking an
absolute value of the second part plus one minus the fourth
term.
The present invention is further related to a system for compact
representation of multi-code signaling that includes a network, a
base station operably connected to the network, and a network
device operably connected to the base station via the network. The
base station determines a number of multi-codes and a code offset
for use by the network device. The base station encodes the number
of multi-codes and code offset into a codeword comprising a compact
representation of multi-code signaling. The codeword is encodable
by the base station and decodable by the remote device without the
need for a look-up table.
In addition, the present invention is related to a mobile device
capable of receiving a codeword representing multi-code signaling
where the mobile device contains hardware or software that
performs: identifying a first part and a second part of the
codeword where the first part represents the code group indicator
and the second part representing the offset indicator; calculating
a first term, the first term equal to one if the second part is
larger than or equal to the first part subtracted from fifteen,
else the first term is equal to zero; calculating a second term by
multiplying the first term by sixteen; identifying a number of
multi-codes by taking an absolute value of the first part plus one
minus the second term; calculating a third term, the third term
equal to one if the number of multi-codes is larger than or equal
to eight, else the third term is equal to zero; calculating a
fourth term by multiplying the third term by seventeen; and
identifying a code offset by taking an absolute value of the second
part plus one minus the fourth term.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is further described in the detailed
description which follows in reference to the noted plurality of
drawings by way of non-limiting examples of embodiments of the
present invention in which like reference numerals represent
similar parts throughout the several views of the drawings and
wherein:
FIG. 1 is a block diagram of a system for compact representation of
multi-code signaling according to an example embodiment of the
present invention;
FIG. 2 is a diagram of a code allocation according to an example
embodiment of the present invention;
FIG. 3 is a diagram of a total encoding matrix for signaling
multi-code allocation according to an example embodiment of the
present invention;
FIG. 4 is a flowchart of an encoding process according to an
example embodiment of the present invention; and
FIG. 5 is a flowchart of an decoding process according to an
example embodiment of the present invention.
DETAILED DESCRIPTION
The particulars shown herein are by way of example and for purposes
of illustrative discussion of the embodiments of the present
invention. The description taken with the drawings make it apparent
to those skilled in the art how the present invention may be
embodied in practice.
Further, arrangements may be shown in block diagram form in order
to avoid obscuring the invention, and also in view of the fact that
specifics with respect to implementation of such block diagram
arrangements is highly dependent upon the platform within which the
present invention is to be implemented, i.e., specifics should be
well within purview of one skilled in the art. Where specific
details (e.g., circuits, flowcharts) are set forth in order to
describe example embodiments of the invention, it should be
apparent to one skilled in the art that the invention can be
practiced without these specific details. Finally, it should be
apparent that any combination of hard-wired circuitry and software
instructions can be used to implement embodiments of the present
invention, i.e., the present invention is not limited to any
specific combination of hardware circuitry and software
instructions.
Although example embodiments of the present invention may be
described using an example system block diagram in an example host
unit environment, practice of the invention is not limited thereto,
i.e., the invention may be able to be practiced with other types of
systems, and in other types of environments.
Reference in the specification to "one embodiment" or "an
embodiment" means that a particular feature, structure, or
characteristic described in connection with the embodiment is
included in at least one embodiment of the invention. The
appearances of the phrase "in one embodiment" in various places in
the specification are not necessarily all referring to the same
embodiment.
The present invention relates to an efficient way to optimize the
signaling of the number of codes used and the offset into the code
tree. The method may be applied to systems where the spreading
factor may be 16, or to systems with a spreading factor different
from 16, while still maintaining encoding efficiency. According to
the present invention, in order to signal which code and offset is
used for a communication link, data may be packed into a
self-decodable structure, which eliminates the need for a look-up
table. The present invention provides a signaling-efficient method
that allows full multi-code flexibility and on-the-fly encoding and
decoding. It may be based on the number of multi-codes and the code
offset which leads to direct and consistent signaling.
The present invention may be useful and implemented in many
applications such as WCDMA (Wideband Code Division Multiple Access)
and specifically HSDPA (High Speed Downlink Packet Access). In this
regard, channelization code set information may be sent over a
HS-SCCH (High Speed Shared Control Channel) for a High Speed
Downlink Shared Channel (HS-DSCH). Orthogonal Variable Spreading
Factor (OVSF) codes may be allocated in such as way that they are
positioned in sequence in the code tree. Therefore, according to
the present invention, a number of multi-codes M starting at an
offset P may be allocated for a given HS-DSCH and signaled on the
HS-SCCH where M and P may be encoded using only three bits for the
code group indicator and four bits for the code offset indicator
for a total of seven bits, one less than conventional methods.
FIG. 1 shows a block diagram of a system for compact representation
of multi-code signaling according to an example embodiment of the
present invention. A base station 10 may communicate with one or
more network devices 12-20 over a network 22. In this example
embodiment, network 22 is a wireless network and network devices
12-20 may be wireless devices. However, the present invention may
be implemented in a network that is wired or wireless. The network
devices may be wireless devices such as a mobile phone, portable
computer, Personal Digital Assistant (PDA), etc., or may be
workstations, servers, etc.
Whenever base station 10 needs to communicate with a network device
12-20, the base station 10 determines how many multi-codes to
allocate for the communication. The base station 10 may then send
information to the network device notifying the network device how
many multi-codes will be used for the communication, and at what
code offset in a code tree the multi-codes start. The base station
10 may make its decision on how many multi-codes may be allocated
to a particular network device or user depending on various
factors, for example, how much information will be transferred from
the base station to the user, what other activities are occurring
at the base station, how much power the base station and/or the
network device has available, what codes in the code tree are free
or being used, etc. The base station 10 may encode the number of
multi-codes and code offset information using an encoding function
24. Each network device 12-20 may include a decoding function 26 to
decode the codeword from the base station 10 and extract the number
of multi-codes and code offset information. Base station 10 and
network devices 12-20 may all contain both encoding functions
and/or decoding functions. The encoding functions and/or decoding
functions may be implemented in hardware, software, microcode, or a
combination thereof.
FIG. 2 shows a diagram of a code allocation according to an example
embodiment of the present invention. A code tree 30 shows a
spreading factor of 16 where 15 multi-codes are available to be
allocated to one or more users. A base station that communicates
with the user or network device determines how many multi-codes and
at what code offset may be given to a user. The base station may
send this information to the user in a codeword. In this example
embodiment, codes at offsets 7-11 have been allocated to one user.
These codes are all consecutive. Thus, the user or network device
has been allocated five multi-codes starting at code offset 7 by a
base station. According to the present invention, this information
may be sent to the user in a codeword comprising a reduced number
of bits, e.g., seven bits. A first part of the codeword may contain
a code group indicator and a second part of the codeword may
contain an offset indicator. The present invention is not limited
by the order that the code group indicator and the offset indicator
may appear in the codeword since this may be implementation
dependent.
FIG. 3 shows a diagram of a total encoding matrix for signaling
multi-code allocation according to an example embodiment of the
present invention. The matrix shows a pair of numbers, one on top
representing the number of multi-codes, and one on bottom
representing an offset from left to right in the code tree. The
associated code indicators are shown on the left side of the matrix
vertically, and the associated offset indicators are shown on top
of the matrix horizontally.
In methods for compact representation of multi-code signaling
according to the present invention, multi-codes are clustered with
a total number of possible offset combinations of 15. In this
sense, the 1 multi-code and 15 multi-code situations are grouped
together as one, the 2 multi-code situation is grouped with the 14
multi-code operation, and so forth. Thus, a total of eight groups
are formed (1/15, 2/14, 3/13, 4/12, 5/11, 6/10, 7/9, and 8/8) which
can be represented by 3-bit signaling. The next issue is then to
identify which of the two code situations is active and what is the
exact code offset. This aspect is achieved by utilizing that the
total number of code-offsets is 16 for each cluster allowing a
4-bit representation.
Methods for compact representation of multi-code signaling
according to the present invention may be implemented in many was
to achieve a codeword containing the code indicator information and
code offset information in less than eight bits. The following
details an example possible encoding process according to the
present invention where a codeword is needed to signal m
multi-codes with code-offset .DELTA.. The first portion of the
codeword, CW1, may represent a code group indicator. The second
portion of the codeword, CW2, may represent a tree offset
indicator. Equation 1 may be used to encode the code group
indicator and equation 2 may be used to encode the tree offset
indicator. Three first bits: CW1=min(m,16-m)-1 (1)) Four last bits:
CW2=|.DELTA.-1-(m>7)*15| (2) The "min" outside of the
parenthesis denotes that the minimum value of the two terms inside
the parentheses (separated by a comma) is taken. The term (m>7)
is either 1 or 0 depending on whether the condition is fulfilled or
not, i.e., true is denoted by 1 and visa versa. The symbol "*"
denotes a multiply operation. The two bars | denote that an
absolute value is taken of the resultant value of the terms inside
the two bars.
For example, a codeword needed to signal 12 multi-codes with
code-offset 2 is: CW1=min(12,4)-1=3=`011`
CW2=|2-1-(12>7)*15|=14=`1110` Therefore, the total codeword
becomes `0111110` (or `1110011` depending on implementation). This
codeword may be sent from a base station to a network device.
FIG. 4 shows a flowchart of an encoding process according to an
example embodiment of the present invention. A number of
multi-codes and code offset are determined S1. A codeword is
formulated that includes a code group indicator and an offset
indicator S2. The minimum value of the multi-code number and
sixteen minus the multi-code number is obtained S3. A first part of
a codeword is determined by subtracting one from the minimum value
obtained S4. The first part represents the code group indicator. A
second term is determined that equals zero if seven is larger than
the multi-code number or one if the multi-code number is larger
than seven S5. A fourth term is determined by multiplying the
second term by fifteen S6. A third term is determined by
subtracting the fourth term from the code offset minus one S7. A
second part of the codeword is determined by taking an absolute
value of the third term S8. The second part represents the offset
indicator. The codeword is formed by concatenating the first part
of the codeword with the second part of the codeword S9.
Upon receipt of the codeword, the network device may then have to
decode the codeword to determine the number of multi-codes and the
code offset. The following details an example possible decoding
process according to the present invention where extraction of the
number of multi-codes (m) and the code-offset (.DELTA.) from a
7-bit codeword (CW1+CW2) is achieved. Equation 3 may be used to
extract a code group indicator from the codeword. Equation 4 may be
used to extract a tree offset indicator from the codeword.
m=|CW1+1-(CW2.gtoreq.(15-CW1))*16| (3)
.DELTA.=|CW2+1-(m.gtoreq.8)*17| (4) For the example shown above we
have m=|3+1-(14.gtoreq.12)*16|=12 .DELTA.=|14+1-(12.gtoreq.7)*17|=2
which are the signaled values.
FIG. 5 shows a flowchart of a decoding process according to an
example embodiment of the present invention. A codeword is
identified that includes a code group indicator and an offset
indicator S20. A first part and a second part of a codeword are
identified S21. The first part may represent the code group
indicator and the second part may represent the offset indicator. A
first term is calculated where the first term equals one if the
second part is larger than or equal to the first part subtracted
from fifteen, else the first term is equal to zero S22. A second
term is determined by multiplying the first term by sixteen S23.
The number of multi-codes is determined by taking an absolute value
of: the first part plus one minus the second term S24. A third term
is determined where the third term equals one if the number of
multi-codes is larger than or equal to eight, else the third term
equals zero S25. A fourth term is determined by multiplying the
third term by seventeen S26. The code offset is determined by
taking an absolute value of the second part plus one minus the
fourth term S27.
In another encoding embodiment of the present invention, Equation 5
may be used to encode the code group indicator and equation 6 may
be used to encode the tree offset indicator. Three first bits:
CW1=min(m-1,15-m) (5) Four last bits: CW2=|.DELTA.-1-[m/8]*15| (6)
The "min" outside of the parenthesis denotes that the minimum value
of the two terms inside the parentheses (separated by a comma) is
taken. The symbol "/" denotes division, and the brackets [] denote
rounding to the nearest lower integer. The symbol "*" denotes a
multiply operation. The two bars | denote that an absolute value is
taken of the resultant value of the terms inside the two bars. This
encoding embodiment produces the same results, a code-word (CW1
CW2) totaling only seven bits.
The following shows some example computer pseudo language for
encoding and decoding according to the present invention. However,
encoding and decoding according to the present invention are not
limited by these representations.
Encoding:
TABLE-US-00001 if(m<8) BEGIN CW1=m-1 CW2=.DELTA.-1 END else
BEGIN CW1=15-m CW2=16-.DELTA. END Decoding: m = CW1+1 .DELTA. =
CW2+1 if(.DELTA. > 16-m) BEGIN .DELTA. = 16-CW2 m = 16-(CW1+1)
END
In methods for compact representation of multi-code signaling
according to the present invention, the encoding and/or the
decoding may be implemented in a hardware encoder and decoder
respectively, implemented in computer software, implemented in
firmware, etc. Moreover, although typically a base station performs
the encoding and a network node performs the decoding, a base
station and network node may contain either the encoding function
or the decoding function, or may contain both.
Methods for compact representation of multi-code signaling
according to the present invention is advantageous in that full
multi-code flexibility may be maintained such that high HS-DSCH
spectral efficiency and RRM flexibility are retained. Moreover, the
codeword is self-decodable by network devices, therefore,
eliminating the need for a code look-up table, thus saving storage
space. Therefore, all parameters may be calculated from the
received codeword. Further, being able to transmit the information
using less bits saves power and allows use of the used bit(s) for
the transmission of other information. The present invention is
highly advantageous for supporting HSDPA (High Speed Downlink
Packet Access) for WCDMA (Wideband Code Division Multiple Access)
where the users spreading factor is set to the fixed number of
16.
It is noted that the foregoing examples have been provided merely
for the purpose of explanation and are in no way to be construed as
limiting of the present invention. While the present invention has
been described with reference to a preferred embodiment, it is
understood that the words that have been used herein are words of
description and illustration, rather than words of limitation.
Changes may be made within the purview of the appended claims, as
presently stated and as amended, without departing from the scope
and spirit of the present invention in its aspects. Although the
present invention has been described herein with reference to
particular methods, materials, and embodiments, the present
invention is not intended to be limited to the particulars
disclosed herein, rather, the present invention extends to all
functionally equivalent structures, methods and uses, such as are
within the scope of the appended claims.
* * * * *