U.S. patent application number 14/087518 was filed with the patent office on 2014-03-20 for dynamic buffer status report selection for carrier aggregation.
This patent application is currently assigned to Nokia Solutions and Networks Oy. The applicant listed for this patent is Nokia Solutions and Networks Oy. Invention is credited to Claudio Rosa, Benoist Pierre Sebire, Chunli Wu.
Application Number | 20140078965 14/087518 |
Document ID | / |
Family ID | 43927700 |
Filed Date | 2014-03-20 |
United States Patent
Application |
20140078965 |
Kind Code |
A1 |
Wu; Chunli ; et al. |
March 20, 2014 |
Dynamic Buffer Status Report Selection For Carrier Aggregation
Abstract
In one exemplary aspect of this invention a method includes
buffering data in a user equipment and, in response to an amount of
buffered data exceeding a threshold value, triggering the
generation of a buffer status report and the sending of the buffer
status report to a network access node, where the threshold value
is a function of the capacity of a currently allocated uplink data
transmission resource and some certain amount of time. In another
exemplary embodiment the triggering of the generation of the buffer
status report and the sending of the buffer status report to a
network access node occurs when an amount of buffered data in a
buffer of a particular logical channel group exceeds a maximum
value associated with one of a plurality of buffer status report
tables that is currently in use.
Inventors: |
Wu; Chunli; (Beijing,
CN) ; Sebire; Benoist Pierre; (Tokyo, JP) ;
Rosa; Claudio; (Randers, DK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nokia Solutions and Networks Oy |
Espoo |
|
FI |
|
|
Assignee: |
Nokia Solutions and Networks
Oy
Espoo
FI
|
Family ID: |
43927700 |
Appl. No.: |
14/087518 |
Filed: |
November 22, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13638985 |
Dec 6, 2012 |
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PCT/EP2011/055107 |
Apr 1, 2011 |
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14087518 |
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Current U.S.
Class: |
370/328 |
Current CPC
Class: |
H04L 47/14 20130101;
H04W 28/0252 20130101; H04L 67/06 20130101; H04W 28/12 20130101;
H04W 28/0278 20130101; H04W 72/1221 20130101; H04L 47/30 20130101;
H04L 47/26 20130101; H04L 47/29 20130101 |
Class at
Publication: |
370/328 |
International
Class: |
H04L 29/08 20060101
H04L029/08 |
Claims
1-48. (canceled)
49. A method, comprising: buffering data in a user equipment; and
storing in the user equipment a plurality of buffer status report
tables, where each of the plurality of buffer status report tables
has a different maximum value and granularity.
50. The method of claim 49, further comprising: generating a buffer
status report for the buffered data in accordance with a selected
one of the plurality of buffer status report tables; and sending
the generated buffer status report to a network access node.
51. The method of claim 49, further comprising: selecting, by the
user equipment, a buffer status report table from the plurality of
buffer status report tables for use.
52. The method of claim 51, where the user equipment selects the
buffer status report table that is currently in use according to an
amount of buffered data by selecting the buffer status report table
that has the smallest maximum value that does not exceed the amount
of currently buffered data.
53. The method of claim 51, further comprising: identifying the
selected buffer status report table to the network access node
using at least one bit in a medium access control buffer status
report header.
54. The method of claim 49, where at least one of the plurality of
buffer status report tables is composed in consideration of a
number of uplink component carriers in use and in consideration of
uplink multiple input/multiple output operation.
55. The method of claim 49, where the plurality of buffer status
report tables comprises a first buffer status report table
configured for use with an uplink data rate in accordance with a
Release 8 or Release 9 evolved universal terrestrial radio access
network and a second buffer status report table composed so as to
cover a use case of five uplink component carriers and uplink
multiple input/multiple output operation.
56. The method of claim 49, performed as a result of execution of
computer program instructions stored in a non-transitory
computer-readable medium that comprises part of the user
equipment.
57. An apparatus, comprising: a processor; and a memory including
computer program code, where the memory and computer program code
are configured to, with the processor, cause the apparatus at least
to perform, buffering data; and storing a plurality of buffer
status report tables, where each of the plurality of buffer status
report tables has a different maximum value and granularity.
58. The apparatus of claim 57, the memory and computer program code
being configured to, with the processor, cause the apparatus to
further perform: generating a buffer status report for the buffered
data in accordance with a selected one of the plurality of buffer
status report tables; and sending the generated buffer status
report to a network access node.
59. The apparatus of claim 57, the memory and computer program code
being configured to, with the processor, cause the apparatus to
further perform: selecting a buffer status report table from the
plurality of buffer status report tables for use.
60. The apparatus of claim 59, where the apparatus selects the
buffer status report table that is currently in use according to an
amount of buffered data by selecting the buffer status report table
that has the smallest maximum value that does not exceed the amount
of currently buffered data.
61. The apparatus of claim 59, the memory and computer program code
being configured to, with the processor, cause the apparatus to
further perform: identifying the selected buffer status report
table to the network access node using at least one bit in a medium
access control buffer status report header.
62. The apparatus of claim 57, where at least one of the plurality
of buffer status report tables is composed in consideration of a
number of uplink component carriers in use and in consideration of
uplink multiple input/multiple output operation.
Description
TECHNICAL FIELD
[0001] The exemplary and non-limiting embodiments of this invention
relate generally to wireless communication systems, methods,
devices and computer programs and, more specifically, relate to
techniques to formulate reports for a network access element, where
the reports are indicative of an amount of data that is buffered in
a user equipment.
BACKGROUND
[0002] This section is intended to provide a background or context
to the invention that is recited in the claims. The description
herein may include concepts that could be pursued, but are not
necessarily ones that have been previously conceived, implemented
or described. Therefore, unless otherwise indicated herein, what is
described in this section is not prior art to the description and
claims in this application and is not admitted to be prior art by
inclusion in this section.
[0003] The following abbreviations that may be found in the
specification and/or the drawing figures are defined as follows:
[0004] 3GPP third generation partnership project [0005] BS base
station [0006] BSR buffer status report [0007] BW bandwidth [0008]
CA carrier aggregation [0009] CC component carrier [0010] CE
control element [0011] CQI channel quality indicator p1 DL downlink
(eNB towards UE) [0012] eNB E-UTRAN Node B (evolved Node B) [0013]
EPC evolved packet core [0014] E-UTRAN evolved UTRAN (LTE) [0015]
IMTA international mobile telecommunications association [0016]
ITU-R international telecommunication union-radiocommunication
sector [0017] LCG logical channel group [0018] LTE long term
evolution of UTRAN (E-UTRAN) [0019] LTE-A LTE advanced
[0020] MAC medium access control (layer 2, L2) [0021] MCS
modulation coding scheme [0022] MIMO multiple input/multiple output
[0023] MM/MME mobility management/mobility management entity [0024]
NodeB base station [0025] OFDMA orthogonal frequency division
multiple access [0026] OAM operations and maintenance [0027] PDCCH
physical downlink control channel [0028] PDCP packet data
convergence protocol [0029] PDU protocol data unit [0030] PHR power
headroom report [0031] PHY physical (layer 1, L1) [0032] Rel
release [0033] RLC radio link control [0034] RLF radio link failure
[0035] RRC radio resource control. [0036] RRM radio resource
management [0037] SC-FDMA single carrier, frequency division
multiple access [0038] SCH shared channel [0039] SGW serving
gateway [0040] TTI transmission time interval [0041] UE user
equipment, such as a mobile station, mobile node or mobile terminal
[0042] UL uplink (UE towards eNB) [0043] UTRAN universal
terrestrial radio access network
[0044] One modern communication system is known as evolved UTRAN
(E-UTRAN, also referred to as UTRAN-LTE or as E-UTRA). The DL
access technique is OFDMA, and the UL access technique is
SC-FDMA.
[0045] One specification of interest is 3GPP TS 36.300, V8.11.0
(2009-12), "3rd Generation Partnership Project; Technical
Specification Group Radio Access Network; Evolved Universal
Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial
Access Network (EUTRAN); Overall description; Stage (Release 8),"
incorporated by reference herein in its entirety. This system may
be referred to for convenience as LTE Rel-8. In general, the set of
specifications given generally as 3GPP TS 36.xyz (e.g., 36.211,
36.311, 36.312, etc.) may be seen as describing the Release 8 LTE
system. More recently, Release 9 versions of at least some of these
specifications have been published including 3GPP TS 36.300, V9.1.0
(2009-9).
[0046] FIG. 1A reproduces FIG. 4.1 of 3GPP TS 36.300 V8.11.0, and
shows the overall architecture of the EUTRAN system (Rel-8). The
E-UTRAN system 2 includes eNBs, providing the E-UTRAN user plane
(PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations
towards the UE (not shown). The eNBs are interconnected with each
other by means of an X2 interface. The eNBs are also connected by
means of an S1 interface to an EPC, more specifically to a MME by
means of a S1 MME interface and to an S-GW by means of a S1
interface (MME/S-GW 4). The S1 interface supports a many-to-many
relationship between MMEs/S-GWs and eNBs.
[0047] The eNB hosts the following functions:
[0048] functions for RRM: RRC, Radio Admission Control, Connection
Mobility Control, dynamic allocation of resources to UEs in both UL
and DL (scheduling);
[0049] IP header compression and encryption of the user data
stream;
[0050] selection of a MME at UE attachment;
[0051] routing of User Plane data towards the EPC (MME/S-GW);
[0052] scheduling and transmission of paging messages (originated
from the MME);
[0053] scheduling and transmission of broadcast information
(originated from the MME or CAM); and
[0054] a measurement and measurement reporting configuration for
mobility and scheduling
[0055] Also of interest herein are the further releases of 3GPP LTE
(e.g., LTE Rel-10) targeted towards future IMTA systems, referred
to herein for convenience simply as LTE-Advanced (LTE-A). Reference
in this regard may be made to 3GPP TR 36.913, V9.1.0 (2009-12), 3rd
Generation Partnership Project; Technical Specification Group Radio
Access Network; Requirements for Further Advancements for EUTRA
(LTE-Advanced) (Release 9), incorporated by reference herein. A
goal of LTE-A is to provide significantly enhanced services by
means of higher data rates and lower latency with reduced cost.
LTE-A is directed toward extending and optimizing the 3GPP LTE
Rel-8 radio access technologies to provide higher data rates at
lower cost. LTE-A will be a more optimized radio system fulfilling
the ITU-R requirements for IMT-Advanced while keeping backwards
compatibility with LTE Rel-8.
[0056] As is specified in 3GPP TR 36.913, LTE-A should operate in
spectrum allocations of different sizes, including wider spectrum
allocations than those of LTE Rel-8 (e.g., up to 100 MHz) to
achieve the peak data rate of 100 Mbit/s for high mobility and 1
Gbit/s for low mobility. It has been agreed that carrier
aggregation is to be considered for LTE-A in order to support
bandwidths larger than 20 MHz. Carrier aggregation, where two or
more component carriers (CCs) are aggregated, is considered for
LTE-A in order to support transmission bandwidths larger than 20
MHz. The carrier aggregation could be contiguous or non-contiguous.
This technique, as a bandwidth extension, can provide significant
gains in terms of peak data rate and cell throughput as compared to
non-aggregated operation as in LTE Rel-8.
[0057] A terminal may simultaneously receive one or multiple
component carriers depending on its capabilities. A LTE-A terminal
with reception capability beyond 20 MHz can simultaneously receive
transmissions on multiple component carriers. A LTE Rel-8 terminal
can receive transmissions on a single component carrier only,
provided that the structure of the component carrier follows the
Rel-8 specifications. Moreover, it is required that LTE-A should be
backwards compatible with Rel-8 LTE in the sense that a Rel-8 LTE
terminal should be operable in the LTE-A system, and that a LTE-A
terminal should be operable in a Rel-8 LTE system.
[0058] FIG. 1B shows an example of CA, where M Rel-8 component
carriers are combined together to form M.times.Rel-8 BW (e.g.
5.times.20 MHz=100 MHz given M=5). Rel-8 terminals receive/transmit
on one CC, whereas LTE-A terminals may receive/transmit on multiple
CCs simultaneously to achieve higher (wider) band-widths.
[0059] Basically, in CA it is possible to configure a UE to
aggregate a different number of CCs originating from the same eNB,
of possibly different BWs, in the UL and the DL. Rel-8 UEs are
assumed to be served by a single stand-alone CC, while Release 10
(LTE-A) terminals can be configured to receive or transmit
simultaneously on multiple aggregated CCs in the same TTI.
[0060] As is currently specified for LTE, one subframe is equal to
one millisecond, and comprises two 0.5 millisecond slots.
[0061] In addition, configured CCs can be de-activated in order to
reduce the UE power consumption. In this case the UE monitoring
activity of a de-activated carrier is reduced (e.g., no PDCCH
monitoring and CQI measurements are needed). This mechanism can be
referred to as carrier activation/deactivation.
[0062] Furthermore, to assist the eNB scheduler functionality the
eNB can configure UEs to send BSRs and PHRs in the UL. Reference in
this regard can be made to 3GPP TS 36.321 V9.1.0 (2009-12)
Technical Specification 3rd Generation Partnership Project;
Technical Specification Group Radio Access Network; Evolved
Universal Terrestrial Radio Access (E-UTRA) Medium Access Control
(MAC) protocol specification (Release 9), such as in Section 5.4.5
"Buffer Status Reporting" and Section 5.4.6 "Power Headroom
Reporting".
[0063] The BSR indicates the amount of data the UE has available
for transmission, while the PHR provides the eNB with information
about the difference between the nominal UE maximum transmit power
and the estimated power for UL-SCH transmission. BSRs are typically
used by the eNB to select an appropriate transport block size,
while PHRs are typically used to select an appropriate MCS.
[0064] BSRs are sent by the UE in the UL in the form of Buffer
Status Report MAC Control Elements (see 3GPP TS 36.321, Section
6.1.3.1, "Buffer Status Report MAC Control Elements") in which the
Buffer Size (BS) field identifies the total amount of data
available for transmission. The length of this field is specified
as 6 bits and contains exponentially distributed buffer size levels
based on a minimum buffer size level (B.sub.min) a maximum buffer
size level (B.sub.max) and a number of reported buffer size levels
(N).
[0065] Reference can be made, for example, to R2-083101, "Buffer
Size Levels for BSR in E-UTRA Uplink", 3GPP TSG-RAN WG2 Meeting
#62bis, Warsaw, Poland, 30 Jun.-4 Jul. 2008, Source: Ericsson,
Nokia Corporation, Nokia Siemens Networks, Samsung.
[0066] FIG. 3A herein reproduces FIG. 6.1.3.1-1 of 3GPP TS 36.321
and shows a Short BSR and Truncated BSR MAC control element, FIG.
3B herein reproduces FIG. 6.1.3.1-2 of 3GPP TS 36.321 and shows a
Long BSR MAC control element, and FIG. 3C herein reproduces Table
6.1.3.1-1 of 3GPP TS 36.321 and shows buffer size levels for
BSR.
[0067] As is stated in 3GPP TS 36.321, Section 6.1.3.1, Buffer
Status Report (BSR) MAC control elements consist of either the
Short BSR and Truncated BSR format, with one LCG ID field and one
corresponding buffer Size field (see FIG. 3A herein) or the Long
BSR format having four buffer size fields, corresponding to LCG IDs
#0 through #3 (see FIG. 3B herein). In a conventional sense the LCG
is understood to be a group of UL logical channels for which a
single joint buffer fill level is reported by the UE in a BSR. The
mapping of logical channels to LCGs is defined by the eNodeB. The
BSR formats are identified by MAC PDU subheaders with LCIDs as
specified in table 6.2.1-2 (FIG. 3D herein). The fields LCG ID and
Buffer Size are defined as follows. LCG ID: The Logical Channel
Group ID field identifies the group of logical channel(s) for which
buffer status is being reported. The length of the field is 2 bits.
Buffer Size: The Buffer Size field identifies the total amount of
data available across all logical channels of a logical channel
group after the MAC PDU has been built. The amount of data is
indicated as the number of bytes. It includes all data that is
available for transmission in the RLC layer and in the PDCP layer.
The size of the RLC and MAC headers are not considered in the
buffer size computation. The length of this field is 6 bits. The
values taken by the Buffer Size field are shown in Table 6.1.3.1-1
(FIG. 3C herein).
[0068] However, the BS field as specified for LTE Rel-8 and Rel-9
is based on the assumption that only one CC is used in the UL and,
as a result, is not adequate for use with the higher data rates
made possible by the use of CA in Rel-10 and beyond.
SUMMARY
[0069] The foregoing and other problems are overcome, and other
advantages are realized, by the use of the exemplary embodiments of
this invention.
[0070] In a first aspect thereof the exemplary embodiments of this
invention provide a method that comprises buffering data in a user
equipment and, in response to an amount of buffered data exceeding
a threshold value, triggering the generation of a buffer status
report and the sending of the buffer status report to a network
access node, where the threshold value is a function of the
capacity of a currently allocated uplink data transmission resource
and some certain amount of time.
[0071] In another aspect thereof the exemplary embodiments of this
invention provide an apparatus that comprises a processor and a
memory including computer program code. The memory and computer
program code are configured to, with the processor, cause the
apparatus at least to perform buffering data in a user equipment
and, in response to an amount of buffered data exceeding a
threshold value, triggering the generation of a buffer status
report and the sending of the buffer status report to a network
access node, where the threshold value is a function of the
capacity of a currently allocated uplink data transmission resource
and some certain amount of time.
[0072] In another aspect thereof the exemplary embodiments of this
invention provide a method that comprises buffering data in a user
equipment and, in response to an amount of buffered data exceeding
a threshold value, triggering the generation of a buffer status
report and the sending of the buffer status report to a network
access node, where triggering the generation of the buffer status
report occurs when an amount of buffered data in a buffer of a
particular logical channel group exceeds a maximum value associated
with one of a plurality of buffer status report tables that is
currently in use.
[0073] In a still further aspect thereof the exemplary embodiments
of this invention provide an apparatus that comprises a processor
and a memory including computer program code. The memory and
computer program code are configured to, with the processor, cause
the apparatus at least to perform, buffering data in a user
equipment and, in response to an amount of buffered data exceeding
a threshold value, triggering the generation of a buffer status
report and the sending of the buffer status report to a network
access node. The triggering the generation of the buffer status
report occurs when an amount of buffered data in a buffer of a
particular logical channel group exceeds a maximum value associated
with one of a plurality of buffer status report tables that is
currently in use.
BRIEF DESCRIPTION OF THE DRAWINGS
[0074] In the attached Drawing Figures:
[0075] FIG. 1A reproduces FIG. 4.1 of 3GPP TS 36.300, and shows the
overall architecture of the EUTRAN system.
[0076] FIG. 1B shows an example of carrier aggregation as proposed
for the LTE-A system.
[0077] FIG. 2 shows a simplified block diagram of various
electronic devices that are suitable for use in practicing the
exemplary embodiments of this invention.
[0078] FIG. 3A reproduces FIG. 6.1.3.1-1 of 3GPP TS 36.321 and
shows a Short BSR and Truncated BSR MAC control element, FIG. 3B
reproduces FIG. 6.1.3.1-2 of 3GPP TS 36.321 and shows a Long BSR
MAC control element, FIG. 3C reproduces Table 6.1.3.1-1 of 3GPP TS
36.321 and shows Buffer size levels for BSR, and FIG. 3D reproduces
Table 6.2.1-21 of 3GPP TS 36.321 and shows values of the LCID for
the UL-SCH.
[0079] FIG. 4 shows the format of a MAC R/R/E/LCID sub-header, and
reproduces FIG. 6.1.2-2 of 3GPP TS 36.321.
[0080] FIG. 5 is a logic flow diagram that illustrates the
operation of a method, and a result of execution of computer
program instructions embodied on a computer readable memory, in
accordance with the exemplary embodiments of this invention.
[0081] FIG. 6 is a logic flow diagram that illustrates the
operation of a method, and a result of execution of computer
program instructions embodied on a computer readable memory,
further in accordance with the exemplary embodiments of this
invention.
DETAILED DESCRIPTION
[0082] The exemplary embodiments of this invention relate generally
to mobile wireless communication, such as 3GPP LTE-A. The exemplary
embodiments of this invention relate more specifically to the UL
buffer size and the reporting of same. As was noted above, the BSR
as defined in Rel-8 and Rel-9 supports a maximum buffer size of
150,000 bytes (see FIG. 3C). The exemplary embodiments of this
invention address and solve this problem for the case of CA where
significantly higher UL data rates can be supported.
[0083] Before describing in further detail the exemplary
embodiments of this invention, reference is made to FIG. 2 for
illustrating a simplified block diagram of various electronic
devices and apparatus that are suitable for use in practicing the
exemplary embodiments of this invention. In FIG. 2 a wireless
network 1 is adapted for communication over a wireless link 11 with
an apparatus, such as a mobile communication device which may be
referred to as a UE 10, via a network access node, such as a Node B
(base station), and more specifically an eNB 12. The network 1 may
include a network control element (NCE) 14 that may include the
MME/SGW functionality shown in FIG. 1A, and which provides
connectivity with a further network, such as a telephone network
and/or a data communications network (e.g., the internet). The UE
10 includes a controller, such as at least one computer or a data
processor (DP) 10A, a non-transitory computer-readable memory
medium embodied as a memory (MEM) 10B that stores a program of
computer instructions (PROG) 10C, and a suitable radio frequency
(RF) transceiver 10D for bidirectional wireless communications with
the eNB 12 via one or more antennas. The eNB 12 also includes a
controller, such as at least one computer or a data processor (DP)
12A, a computer-readable memory medium embodied as a memory (MEM)
12B that stores a program of computer instructions (PROG) 12C, and
a suitable RF transceiver 12D for communication with the UE 10 via
one or more antennas (typically several when MIMO operation is in
use). The eNB 12 is coupled via a data/control path 13 to the NCE
14. The path 13 may be implemented as the S1 interface shown in
FIG. 1A. The eNB 12 may also be coupled to another eNB via
data/control path 15, which may be implemented as the X2 interface
shown in FIG. 1A.
[0084] For the purposes of describing the exemplary embodiments of
this invention the UE 10 can be assumed to also include a MAC
function or module 10E, and the memory 10B can be assumed to
include one or more data buffers 10F. The memory 10B can also store
one or more buffer size tables. The eNB 12 can be assumed to
include a corresponding MAC function or module 12E. In one
exemplary embodiment the MAC modules 10E, 12E can be compatible
with, and configured to operate using, the MAC procedures defined
in 3GPP TS 36.321, as extended and enhanced in accordance with the
exemplary embodiments of this invention.
[0085] The PROGs 10C and 12C are assumed to include program
instructions that, when executed by the associated DP, enable the
device to operate in accordance with the exemplary embodiments of
this invention, as will be discussed below in greater detail. That
is, the exemplary embodiments of this invention may be implemented
at least in part by computer software executable by the DP 10A of
the UE 10 and/or by the DP 12A of the eNB 12, or by hardware, or by
a combination of software and hardware (and firmware).
[0086] In general, the various embodiments of the UE 10 can
include, but are not limited to, cellular telephones, personal
digital assistants (PDAs) having wireless communication
capabilities, portable computers having wireless communication
capabilities, image capture devices such as digital cameras having
wireless communication capabilities, gaming devices having wireless
communication capabilities, music storage and playback appliances
having wireless communication capabilities, Internet appliances
permitting wireless Internet access and browsing, as well as
portable units or terminals that incorporate combinations of such
functions.
[0087] The computer-readable MEMs 10B and 12B may be of any type
suitable to the local technical environment and may be implemented
using any suitable data storage technology, such as semiconductor
based memory devices, flash memory, magnetic memory devices and
systems, optical memory devices and systems, fixed memory and
removable memory. The DPs 10A and 12A may be of any type suitable
to the local technical environment, and may include one or more of
general purpose computers, special purpose computers,
microprocessors, digital signal processors (DSPs) and processors
based on multi-core processor architectures, as non-limiting
examples.
[0088] Described now in further detail are several aspects of the
exemplary embodiments of this invention.
[0089] In a first aspect of the exemplary embodiments there are
introduced a plurality of buffer size level tables tailored for
different maximum uplink data rates. For example one buffer size
table can be provided with a maximum of 150,000 bytes, thus
corresponding to the same UL data rate as in Rel-8 and Rel-9. This
first table may be identical to the table shown in FIG. 3. A second
table with a maximum of 300,000 bytes, corresponding to twice the
UL data rate of Rel-8 and Rel-9, can also be provided to cover the
case of, for example, the aggregation of two CCs in the UL. In a
similar manner a third buffer size table with a maximum of 450,000
bytes, corresponding to three times the UL data rate of Rel-8 and
Rel-9, can also be provided to cover the case of, for example, the
aggregation of three CCs in the UL.
[0090] In a second aspect of the exemplary embodiments, and when
building/composing an UL BSR MAC Control Element, the MAC function
10E of the UE 10 dynamically selects the buffer size level table to
be used based on the amount of data buffered. The UE 10 selects one
of the tables according to the amount of data it has buffered,
e.g., the UE 10 selects the table with a minimum B.sub.max that
does not exceed its current buffer status (i.e., the table with the
finest granularity). The UE 10 can then indicate to the eNB 12
which table is used via, for example, two R (reserved) bits in the
MAC header for BSR (see the R/R/E/LCID sub-header shown in FIG. 4).
All LCGs use the same BSR table in the Long BSR which is selected
according to the LCG with the most data buffered (or alternatively
according to the LCG that has triggered the BSR).
[0091] In a third aspect of the exemplary embodiments of this
invention there is introduced a threshold-based BSR trigger, with
the threshold being implicitly deduced by the buffer exceeding what
can be supported by currently configured or allocated resource(s)
within some certain time. The time can be configurable or it can be
fixed so as to be the same as the response time (e.g., 16 TTIs used
for calculating the maximum level for the BSR table). The threshold
may be per LCG, e.g., the BSR is triggered when the buffer of a LCG
exceeds the threshold such that another BSR table is to be used
(i.e., the buffer exceeds the value of B.sub.max of the BSR table
currently in use). Alternatively, the threshold value can be
directly configurable by the eNB 12 in DL signaling.
[0092] In accordance with the exemplary embodiments the buffer size
tables can be generated with different B.sub.max values and
exponentially distributed buffer size levels. B.sub.max is
determined by the number of configured/activated UL CCs and/or
whether UL MIMO is configured for each CC. For example, B.sub.max
for two UL CCs can be twice as large as for a single UL CC. The
buffer size levels can be calculated in the same manner as in
Rel-8: i.e., B.sub.k=.left brkt-top.B.sub.min(1+p).sup.k.right
brkt-bot., where p=(B.sub.max/B.sub.min).sup.1/(N-1)31 1, k is the
index, N is maximum index (62 in this example with 6 bits for BS
and one value reserved for an empty buffer), B.sub.min=10
bytes.
[0093] With, for example, the two R bits in the MAC BSR header (see
again FIG. 4), up to four pre-defined tables can be supported and
identified to the eNB 12, where each BRS table has a different
B.sub.max value. The B.sub.max values can be determined by the data
rate supported with different numbers of UL CC and/or with UL MIMO,
and B.sub.k calculated the same way as in the first aspect
discussed above.
[0094] For an implicit threshold, and by example, when one CC is
configured for the UE 10 the BSR is triggered when the buffer
status exceeds 150 Kbytes, which is the maximum value can be
supported with one CC within a 16 TTI response time. Alternatively,
when the allocated resource is 100 Kbyte for a certain TTI, BSR is
triggered if the buffer exceeds 100 Kbytes times some certain time
(e.g., 16 TTI or some configurable time), which means BSR is
triggered when the buffer cannot be emptied with the currently
allocated UL resource within the specified time (e.g., with 16
TTI).
[0095] For the per LCG threshold, and by example assuming the BSR
table used in previous BSRs is B.sub.max=150 Kbytes, then BSR is
triggered when the data buffer of a LCG exceeds 150 kbytes, and
another BSR table is to be used.
[0096] It should be appreciated that the exemplary embodiments of
this invention can be implemented in a variety of different forms.
For example, it is also within the scope of the exemplary
embodiments to take the operation of UL MIMO into account. As such,
the BSR tables are not necessarily linked only to the number of CCs
in use. As one non-limiting example, the UE 10 may store two BSR
tables, with one table identical to (or substantially identical to)
the table used for Rel-8 (e.g., see FIG. 3C), and a second table
composed so as to cover the use case of five UL CCs plus UL
MIMO.
[0097] As can be appreciated, a number of technical effects are
realized by the use of the exemplary embodiments. For example, more
accurate UL buffer information is provided for the eNB 12 to enable
more efficient scheduling and a better determination as to whether
more UL CC(s) need to be configured/activated, or whether some
existing UL CC should be deconfigured/deactivated. The BSR format
need not change from what is already specified for Rel-8 and Rel-9,
and thus the impact on the MAC protocol is minimized, i.e., 6 bits
are still used for the BS for a LCG with a MAC header to indicate
that it is a BSR MAC control element (CE).
[0098] Based on the foregoing it should be apparent that the
exemplary embodiments of this invention provide a method, apparatus
and computer program(s) to enhance the reporting of the amount of
buffered data in the UE 10 to the eNB 12.
[0099] FIG. 5 is a logic flow diagram that illustrates the
operation of a method, and a result of execution of computer
program instructions, in accordance with the exemplary embodiments
of this invention. In accordance with these exemplary embodiments a
method performs, at Block 5A, a step of buffering data in a user
equipment. In block 5B there is a step, performed in response to an
amount of buffered data exceeding a threshold value, of triggering
the generation of a buffer status report and the sending of the
buffer status report to a network access node, where the threshold
value is a function of the capacity of a currently allocated uplink
data transmission resource and some certain amount of time.
[0100] In accordance with the foregoing method, where the uplink
data transmission resource comprises one or more component
carriers, and where the capacity increases as the number of
component carriers increases.
[0101] In accordance with the foregoing method, where the time is
expressed in transmission time intervals (TTIs).
[0102] In accordance with the foregoing method, where the threshold
value is per logical channel group.
[0103] In accordance with the foregoing method, where the threshold
value is related to a maximum amount of buffered data supported by
a buffer status table that is currently in use by the user
equipment.
[0104] In accordance with the foregoing method, where the threshold
value is related to a maximum amount of time that is available
during which the buffered data can be transmitted to the network
access node using the currently allocated uplink data transmission
resource.
[0105] In accordance with the foregoing method, where the uplink
data transmission resource comprises one or more component
carriers, where the capacity increases as the number of component
carriers increases, and where the time is expressed in transmission
time intervals.
[0106] In accordance with the foregoing method, where the user
equipment stores a plurality of buffer status report tables,
individual ones of which correspond to an individual one of a
number of component carriers allocated to the user equipment for
transmitting data on the uplink.
[0107] In accordance with the foregoing method, where the user
equipment stores a plurality of buffer status report tables, where
each of the plurality of buffer status report tables has a
different maximum value and granularity.
[0108] In accordance with the foregoing method, where the user
equipment stores a plurality of buffer status report tables, and
where at least one of the plurality of buffer status report tables
is composed in consideration of a number of uplink component
carriers in use and in consideration of uplink multiple
input/multiple output operation.
[0109] In accordance with the foregoing method, where triggering
the generation of a buffer status report occurs when an amount of
buffered data in a buffer of a particular logical channel group
exceeds a maximum value associated with one of a plurality of
buffer status report tables that is currently in use.
[0110] In accordance with the foregoing method as explained in the
preceding paragraph, where the user equipment selects the buffer
status report table that is currently in use according to an amount
of buffered data by selecting the buffer status report table that
has the smallest maximum value that does not exceed the amount of
currently buffered data.
[0111] In accordance with the foregoing method as explained in the
preceding paragraph, and further comprising identifying the
selected buffer status report table to the network access node
using at least one bit in a medium access control buffer status
report header.
[0112] In accordance with the foregoing method, performed as a
result of execution of computer program instructions stored in a
non-transitory computer-readable medium that comprises part of the
user equipment.
[0113] FIG. 6 is a logic flow diagram that illustrates the
operation of a method, and a result of execution of computer
program instructions, further in accordance with the exemplary
embodiments of this invention. In accordance with these exemplary
embodiments a method performs, at Block 6A, a step of buffering
data in a user equipment. At Block 6B there is a step performed, in
response to an amount of buffered data exceeding a threshold value,
of triggering the generation of a buffer status report and the
sending of the buffer status report to a network access node, where
triggering the generation of the buffer status report occurs when
an amount of buffered data in a buffer of a particular logical
channel group exceeds a maximum value associated with one of a
plurality of buffer status report tables that is currently in
use.
[0114] In accordance with the foregoing method, where the user
equipment selects the buffer status report table that is currently
in use according to an amount of buffered data by selecting the
buffer status report table that has the smallest maximum value that
does not exceed the amount of currently buffered data.
[0115] In accordance with the foregoing method, and further
comprising identifying the selected buffer status report table to
the network access node using at least one bit in a medium access
control buffer status report header.
[0116] In accordance with the foregoing method, where the medium
access control buffer status report header also identifies the
particular logical channel group.
[0117] The various blocks shown in FIGS. 5 and 6 may be viewed as
method steps, and/or as operations that result from operation of
computer program code, and/or as a plurality of coupled logic
circuit elements constructed to carry out the associated
function(s). That is, also encompassed by these exemplary
embodiments are apparatus that are configured to operate so as to
execute the exemplary methods described above with respect to FIGS.
5 and 6.
[0118] Also encompassed by these exemplary embodiments is an
apparatus, such as a network access node (e.g., the eNB 12), that
is configured to respond to and interpret the BSRs received on the
UL from the UE 10.
[0119] The exemplary embodiments also pertain to an apparatus that
comprises means for buffering data in a user equipment and means,
responsive to an amount of buffered data exceeding a threshold
value, for triggering the generation of a buffer status report and
the sending of the buffer status report to a network access node,
where the threshold value is a function of the capacity of a
currently allocated uplink data transmission resource and some
certain amount of time.
[0120] The exemplary embodiments also pertain to an apparatus that
comprises means for buffering data in a user equipment and means,
responsive to an amount of buffered data exceeding a threshold
value, for triggering the generation of a buffer status report and
the sending of the buffer status report to a network access node,
where triggering the generation of the buffer status report occurs
when an amount of buffered data in a buffer of a particular logical
channel group exceeds a maximum value associated with one of a
plurality of buffer status report tables that is currently in
use.
[0121] In general, the various exemplary embodiments may be
implemented in hardware or special purpose circuits, software,
logic or any combination thereof. For example, some, aspects may be
implemented in hardware, while other aspects may be implemented in
firmware or software which may be executed by a controller,
microprocessor or other computing device, although the invention is
not limited thereto. While various aspects of the exemplary
embodiments of this invention may be illustrated and described as
block diagrams, flow charts, or using some other pictorial
representation, it is well understood that these blocks, apparatus,
systems, techniques or methods described herein may be implemented
in, as non-limiting examples, hardware, software, firmware, special
purpose circuits or logic, general purpose hardware or controller
or other computing devices, or some combination thereof.
[0122] It should thus be appreciated that at least some aspects of
the exemplary embodiments of the inventions may be practiced in
various components such as integrated circuit chips and modules,
and that the exemplary embodiments of this invention may be
realized in an apparatus that is embodied as an integrated circuit.
The integrated circuit, or circuits, may comprise circuitry (as
well as possibly firmware) for embodying at least one or more of a
data processor or data processors, a digital signal processor or
processors, baseband circuitry and radio frequency circuitry that
are configurable so as to operate in accordance with the exemplary
embodiments of this invention.
[0123] Various modifications and adaptations to the foregoing
exemplary embodiments of this invention may become apparent to
those skilled in the relevant arts in view of the foregoing
description, when read in conjunction with the accompanying
drawings. However, any and all modifications will still fall within
the scope of the non-limiting and exemplary embodiments of this
invention.
[0124] For example, while the exemplary embodiments have been
described above in the context of the LTE-A system, it should be
appreciated that the exemplary embodiments of this invention are
not limited for use with only this particular types of wireless
communication system and that they may be used to advantage in
other wireless communication systems, such as systems where
component aggregation is employed.
[0125] It should be noted that the terms "connected," "coupled," or
any variant thereof, mean any connection or coupling, either direct
or indirect, between two or more elements, and may encompass the
presence of one or more intermediate elements between two elements
that are "connected" or "coupled" together. The coupling or
connection between the elements can be physical, logical, or a
combination thereof. As employed herein two elements may be
considered to be "connected" or "coupled" together by the use of
one or more wires, cables and/or printed electrical connections, as
well as by the use of electromagnetic energy, such as
electromagnetic energy having wavelengths in the radio frequency
region, the microwave region and the optical (both visible and
invisible) region, as several non-limiting and non-exhaustive
examples.
[0126] Further, the various names used for the described
parameters, channels and message elements are not intended to be
limiting in any respect, as these parameters, channels and message
elements may be identified by any suitable names.
[0127] Furthermore, some of the features of the various
non-limiting and exemplary embodiments of this invention may be
used to advantage without the corresponding use of other features.
As such, the foregoing description should be considered as merely
illustrative of the principles, teachings and exemplary embodiments
of this invention, and not in limitation thereof.
* * * * *