U.S. patent application number 15/951725 was filed with the patent office on 2018-10-18 for methods and nodes relating to system information acquisition during flexible subframe operation.
The applicant listed for this patent is Telefonaktiebolaget LM Ericsson (publ). Invention is credited to Ali Behravan, Muhammad Kazmi, Iana Siomina.
Application Number | 20180302885 15/951725 |
Document ID | / |
Family ID | 52682888 |
Filed Date | 2018-10-18 |
United States Patent
Application |
20180302885 |
Kind Code |
A1 |
Behravan; Ali ; et
al. |
October 18, 2018 |
Methods and Nodes Relating to System Information Acquisition During
Flexible Subframe Operation
Abstract
The disclosure relates to a method performed in a wireless
device located in a first cell operated by a network node of a
wireless communication system. The method comprises acquiring
system information of a second cell using at least one autonomous
gap during a time period. The wireless device is configured with a
flexible subframe allocation scheme in the first cell during at
least a part of the time period. The method further comprises
obtaining a value Nmin corresponding to a minimum number of uplink
feedback signals, where the value Nmin is associated with the
flexible subframe allocation scheme. The method also comprises
transmitting at least the minimum number Nmin of uplink feedback
signals in response to downlink data during the time period. The
disclosure also relates to a method in the network node and to the
wireless device and the network node.
Inventors: |
Behravan; Ali; (Stockholm,
SE) ; Kazmi; Muhammad; (Bromma, SE) ; Siomina;
Iana; (Taby, SE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Telefonaktiebolaget LM Ericsson (publ) |
Stockholm |
|
SE |
|
|
Family ID: |
52682888 |
Appl. No.: |
15/951725 |
Filed: |
April 12, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14427498 |
Mar 11, 2015 |
9974073 |
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PCT/SE2015/050102 |
Jan 29, 2015 |
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15951725 |
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61933892 |
Jan 31, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 48/08 20130101;
H04W 72/1263 20130101; H04L 1/1812 20130101; H04W 36/0088 20130101;
H04W 72/0413 20130101; H04W 72/044 20130101 |
International
Class: |
H04W 72/04 20060101
H04W072/04; H04W 72/12 20060101 H04W072/12; H04W 36/00 20060101
H04W036/00; H04L 1/18 20060101 H04L001/18; H04W 48/08 20060101
H04W048/08 |
Claims
1. A method performed in a User Equipment (UE) located in a serving
cell operated by an eNodeB of an Evolved Universal Terrestrial
Radio Access Network (E-UTRAN), the method comprising: receiving a
request from the eNodeB to report system information of a second
cell; and in response to the request: determining that the UE is
configured with a flexible subframe allocation scheme in the
serving cell during at least a part of a time period, retrieving a
value Nmin stored in the UE, the value Nmin being associated with
the flexible subframe allocation scheme configuration and
corresponding to a serving cell performance requirement of a
minimum number of uplink feedback signals to send in response to
continuous downlink data received in the serving cell during the
time period, acquiring system information of the second cell using
at least one autonomous gap during the time period, while
fulfilling the serving cell performance requirement, and
transmitting the acquired system information of the second cell to
the eNodeB.
2. The method according to claim 1, wherein the request to report
system information is for the purpose of having the UE report a
Cell Global Identifier (CGI) uniquely identifying the second cell,
and wherein the acquired system information comprises the CGI.
3. The method according to claim 1, wherein the UE is configured
with the flexible subframe allocation scheme based on configuration
information received from the eNodeB.
4. The method according to claim 1, wherein the flexible subframe
allocation scheme is a dynamic time division duplex allocation
scheme, or an Enhanced Interference Mitigation and Traffic
Adaptation (eIMTA).
5. The method according to claim 1, wherein the flexible subframe
allocation scheme configuration implies that different
uplink-downlink configurations may be used in the serving cell and
the second cell, respectively, during a same radio frame, or may be
used in different radio frames in the serving cell.
6. A method performed in an eNodeB of an Evolved Universal
Terrestrial Radio Access Network (E-UTRAN), wherein a User
Equipment (UE) is served by a serving cell operated by the eNodeB,
the method comprising: transmitting a request to the UE to report
system information of a second cell, wherein the UE is configured
with a flexible subframe allocation scheme in the serving cell
during at least a part of a time period; retrieving a value Nmin
stored in the eNodeB, the value Nmin being associated with the
flexible subframe allocation scheme configuration and corresponding
to a serving cell performance requirement of a minimum number of
uplink feedback signals that the UE shall transmit in response to
continuous downlink data in the serving cell during the time
period; and receiving system information of the second cell from
the UE, acquired by the UE using at least one autonomous gap during
the time period, while fulfilling the serving cell performance
requirement.
7. The method according to claim 6, further comprising transmitting
configuration information to the UE, configuring the UE to operate
with the flexible subframe allocation scheme in the serving cell
during at least part of the time period.
8. The method according to claim 6, wherein the request to report
system information is for the purpose of having the UE report a
Cell Global Identifier (CGI) that uniquely identifies the second
cell, wherein the received system information comprises the
CGI.
9. The method according to claim 6, further comprising enabling the
UE to fulfill the serving cell performance requirement by adapting
a scheduling scheme for the UE based on the minimum number of
uplink feedback signals that the UE shall transmit in response to
the continuous downlink data in the serving cell during the time
period and scheduling the UE using the adapted scheduling
scheme.
10. The method according to claim 6, further comprising enabling
the UE to fulfill the serving cell performance requirement by
adapting one or more parameters of the flexible subframe allocation
scheme configuration based on the minimum number of uplink feedback
signals that the UE shall transmit in response to the continuous
downlink data in the serving cell during the time period.
11. The method according to claim 6, wherein the flexible subframe
allocation scheme is a dynamic time division duplex allocation
scheme, or an Enhanced Interference Mitigation and Traffic
Adaptation (eIMTA).
12. The method according to claim 6, wherein the flexible subframe
allocation scheme configuration implies that different
uplink-downlink configurations may be used in the serving cell and
the second cell respectively during a same radio frame or may be
used in different radio frames in the serving cell.
13. A User Equipment (UE) configured for operation in an Evolved
Universal Terrestrial Radio Access Network (E-UTRAN), the UE
comprising: communication circuitry configured for wireless
communication with one or more eNodeBs of the E-UTRAN; and
processing circuitry configured to: receive, via the communication
circuitry, a request sent in a serving cell of the UE, the request
requesting the UE to report system information of a second cell and
sent from an eNodeB that operates the serving cell; and responsive
to the request: determine that the UE is configured with a flexible
subframe allocation scheme in the serving cell during at least a
part of a time period; retrieve a value Nmin stored in the UE, the
value Nmin being associated with the flexible subframe allocation
scheme configuration and corresponding to a serving cell
performance requirement of a minimum number of uplink feedback
signals to send in response to continuous downlink data received in
the serving cell during the time period; acquire, via the
communication circuitry, system information of the second cell
using at least one autonomous gap during the time period, while
fulfilling the serving cell performance requirement; and transmit,
via the communication circuitry, the acquired system information of
the second cell to the eNodeB.
14. The UE according to claim 13, wherein the request to report
system information is for the purpose of having the UE report a
Cell Global Identifier (CGI) uniquely identifying the second cell,
and wherein the acquired system information comprises the CGI.
15. The UE according to claim 13, wherein the UE is configured with
the flexible subframe allocation scheme based on configuration
information received from the eNodeB.
16. The UE according to claim 13, wherein the flexible subframe
allocation scheme is a dynamic time division duplex allocation
scheme, or an Enhanced Interference Mitigation and Traffic
Adaptation (eIMTA).
17. The UE according to claim 13, wherein the flexible subframe
allocation scheme configuration implies that different
uplink-downlink configurations may be used in the serving cell and
the second cell, respectively, during a same radio frame, or may be
used in different radio frames in the serving cell.
18. An eNodeB configured for operation in an Evolved Universal
Terrestrial Radio Access Network (E-UTRAN, the eNodeB comprising:
communication circuitry configured for wireless communication with
User Equipments (UEs); and processing circuitry configured to:
transmit, via the communication circuitry, a request to a UE served
by a cell operated by the eNodeB, requesting the UE to report
system information of a second cell, wherein the UE is configured
with a flexible subframe allocation scheme in the serving cell
during at least a part of a time period; retrieve a value Nmin
stored in the eNodeB, the value Nmin being associated with the
flexible subframe allocation scheme configuration and corresponding
to a serving cell performance requirement of a minimum number of
uplink feedback signals that the UE shall transmit in response to
continuous downlink data in the serving cell during the time
period; and receive, via the communication circuitry, system
information of the second cell from the UE, acquired by the UE
using at least one autonomous gap during the time period, while
fulfilling the serving cell performance requirement.
19. The eNodeB according to claim 18, wherein the processing
circuitry is further configured to transmit configuration
information to the UE, configuring the UE to operate with the
flexible subframe allocation scheme in the serving cell during at
least part of the time period.
20. The eNodeB according to claim 18, wherein the request to report
system information is for the purpose of having the UE report a
Cell Global Identifier (CGI) that uniquely identifies the second
cell, wherein the received system information comprises the
CGI.
21. The eNodeB according to claim 18, wherein the processing
circuitry is configured to enable the UE to fulfill the serving
cell performance requirement by adapting a scheduling scheme for
the UE based on the minimum number of uplink feedback signals that
the UE shall transmit in response to the continuous downlink data
in the serving cell during the time period and scheduling the UE
using the adapted scheduling scheme.
22. The eNodeB according to claim 18, wherein the processing
circuitry is configured to enable the UE to fulfill the serving
cell performance requirement by adapting one or more parameters of
the flexible subframe allocation scheme configuration based on the
minimum number of uplink feedback signals that the UE shall
transmit in response to the continuous downlink data in the serving
cell during the time period.
23. The eNodeB according to claim 18, wherein the flexible subframe
allocation scheme is a dynamic time division duplex allocation
scheme, or an Enhanced Interference Mitigation and Traffic
Adaptation (eIMTA).
24. The eNodeB according to claim 18, wherein the flexible subframe
allocation scheme configuration implies that different
uplink-downlink configurations may be used in the serving cell and
the second cell respectively during a same radio frame or may be
used in different radio frames in the serving cell.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 14/427,498, filed 11 Mar. 2015, which is a U.S. National Phase
Application of PCT/SE2015/050102, filed 29 Jan. 2015, which claims
benefit of U.S. Provisional Application No. 61/933,892, filed 31
Jan. 2014. The entire contents of each aforementioned application
is incorporated herein by reference.
TECHNICAL FIELD
[0002] Embodiments herein relate to wireless communication systems,
such as telecommunication systems. A method and a wireless device
for managing uplink (UL) feedback during System Information (SI)
acquisition when flexible subframe operation is configured as well
as a method and a network node for assisting the wireless device to
manage UL feedback during SI acquisition when flexible subframe
operation is configured are disclosed. Moreover, corresponding
computer programs and computer program products are disclosed.
BACKGROUND
[0003] Within a telecommunication system, it is possible to apply a
flexible subframe scheme in order to better adapt the number of UL
and downlink (DL) subframes to current traffic conditions. E.g.
when there is mostly DL traffic, it is preferred to use a scheme
with many DL subframes.
Flexible Subframes in Dynamic Time Division Duplex
[0004] In a dynamic Time Division Duplex (TDD) system, a group of
subframes are fixed subframes, i.e. they are either UL or DL
subframes in all radio frames, while others are flexible subframes,
i.e. in some radio frames they can be UL subframe, while in other
radio frames same subframe can be DL subframes or even special
subframes. The assignment of the UL or DL direction is done in a
dynamic manner on the basis of a radio frame or multiple radio
frames. Flexible subframes are also interchangeably called dynamic
subframes.
[0005] Table 1 shows the existing TDD configurations (also known as
UL-DL configurations or TDD UL-DL configurations).
TABLE-US-00001 TABLE 1 UL-DL configurations DL-to-UL Switch- UL-DL
point Subframe number configuration periodicity 0 1 2 3 4 5 6 7 8 9
0 5 ms D S U U U D S U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U
D D D S U D D 3 10 ms D S U U U D D D D D 4 10 ms D S U U D D D D D
D 5 10 ms D S U D D D D D D D 6 5 ms D S U U U D S U U D
[0006] FIG. 1a shows as an example of a dynamic TDD configuration
made from two legacy TDD configurations (configuration 0 and 2).
The TDD configuration is also called UL/DL subframe
configuration.
Configuration of Flexible Subframes
[0007] A flexible subframe is configured in a cell and the UEs are
also informed about the flexible subframes by means of signaling. A
subframe is in this document referred to as flexible if it is an UL
subframe in one TDD configuration and a DL or special subframe in a
second TDD configuration. More specifically a subframe can be a
flexible subframe if it is an UL subframe in one TDD configuration
and a DL or a special subframe in another TDD configuration. A
subframe can also be flexible if it is an UL subframe in one TDD
configuration and a DL subframe in a second TDD configuration. The
first and second TDD configurations can be used in different radio
frames in the same cell or in different cells during the same or
different radio frames. A TDD configuration may also
interchangeably be called an UL-DL configuration or a special
subframe configuration. The two configurations may either be the
configuration used for UL scheduling and Hybrid Automatic Repeat
Request (HARQ) timing and the configuration used for DL HARQ
timing. It could otherwise be based on fixed configurations, e.g.
configuration 0 and 5 in Table 1. In this example (configuration 0
and 5) subframes {3, 4, 7, 8, 9} would be flexible.
[0008] It is currently being discussed in 3GPP that the TDD
configuration that will be applied for a period of time, e.g. a
period of 10, 20, 40, 80 ms, is communicated to the UE by means of
DL Control Information (DCI) format 1C. The UE may need to apply
this configuration from the current radio frame or in any following
radio frame.
Flexible Subframes in Half Duplex Operation
[0009] In half duplex (HD), or more specifically in HD Frequency
Division Duplex (HD-FDD), the UL and DL transmissions take place on
different paired carrier frequencies but not simultaneously in time
in the same cell. This means the UL and DL transmissions take place
in different time slots or subframes. In other words UL and DL
subframes do not overlap in time. The number and location of
subframes used for DL, UL and subframes that are unused can vary on
the basis of a radio frame or multiple radio frames. For example in
one frame (say frame#1) subframes 9, 0, 4 and 5 are used for DL and
subframes 2, 5 and 7 are used for UL transmission. But in another
frame (say frame#2) subframes 0 and 5 are used for DL and subframes
2, 3, 5, 7 and 8 are used for UL transmission. Some subframes are
unused to account for switching between UL and DL subframes. In
this example subframe 3, 4, 8 and 9 can be considered as flexible
subframes since they change between UL, DL and unused subframes
across radio frames #1 and #2.
SI Acquisition Using Autonomous Gaps
[0010] In High Speed Packet Access (HSPA) and Long Term Evolution
(LTE) the serving cell can request the UE to acquire the SI of the
target cell. More specifically the SI is read by the UE to acquire
the cell global identifier (CGI), which uniquely identifies the
target cell.
[0011] The UE reads the SI of the target cell (e.g. intra-,
inter-frequency or inter-RAT cell) upon receiving an explicit
request from the serving network node via Radio Resource Control
(RRC) signaling e.g. from a Radio Network Controller (RNC) in HSPA
or eNode B in case of LTE. The acquired SI is then reported to the
serving cell. The signaling messages are defined in the relevant
HSPA and LTE specifications.
[0012] In LTE the UE has to read the master information block (MIB)
and SI block#1 (SIB1) of the target Evolved Universal Terrestrial
Radio Access Network (E-UTRAN) cell (which can be FDD or TDD) to
acquire its CGI (also known as E-UTRAN CGI(ECGI)) when the target
cell is E-UTRAN intra- or inter-frequency. The MIB and SIB1 are
sent on the Physical Broadcast Channel (PBCH) and Physical Downlink
Shared Channel (PDSCH) respectively over pre-defined scheduling
instances.
[0013] In order to acquire the SI which contains the CGI of the
target cell, the UE has to read at least part of the SI including
master information block (MIB) and the relevant SI block (SIB) as
described later. The terms SI reading/decoding/acquisition,
CGI/ECGI reading/decoding/acquisition, CSG SI
reading/decoding/acquisition are sometimes interchangeably used.
For consistency the broader term "SI reading or acquisition" is
used.
[0014] The reading of SI for the acquisition of CGI is carried out
during measurement gaps which are autonomously created by the UE.
The number of gaps and their size thus depends upon UE
implementation as well as on other factors such as the radio
conditions, or type of SI to be read.
[0015] For TDD intra-frequency measurements, if autonomous gaps are
used for reporting CGI, the UE may be required to be able to
identify a new CGI of E-UTRA cell within
T.sub.identify.sub._.sub.CGI,
intra=T.sub.basic.sub._.sub.identify.sub._.sub.CGI, intra ms, were
T.sub.basic.sub._.sub.identify.sub._.sub.CGI, intra is the maximum
allowed time for the UE to identify a new CGI of an E-UTRA cell.
T.sub.basic.sub._.sub.identify.sub._.sub.GGI, intra is equal to 150
ms. This requirement applies when no Discontinuous Reception (DRX)
is used.
[0016] If there is continuous DL data allocation and no DRX is used
and no measurement gaps are configured, then the UE shall be able
to transmit at least the number of
Acknowledgements/non-acknowledgements (ACK/NACKs) stated in the
following Table 2 during the identification of a new CGI of a
E-UTRA cell. The continuous transmission herein means that the
network node transmits data in all DL subframes during the
T.sub.basic.sub._.sub.identify.sub._.sub.CGI, intra.
TABLE-US-00002 TABLE 2 Requirement on minimum number of ACK/NACKs
to transmit during T.sub.basic.sub.--.sub.identify.sub.--.sub.CGI,
intra Minimum number of UL/DL transmitted configuration ACK/NACKs 0
18 1 35 2 43 3 36 4 39 5 42 6 30
Problem
[0017] The UE acquires the SI of a non-serving cell in autonomous
gaps. During the autonomous gaps the UE does not receive and
transmit in a serving cell and can thus not receive any type of
serving signal including SI of the serving cell. This is because
the UE can decode only one physical channel (e.g. PBCH, PDSCH) at a
time, and the SI is transmitted on PBCH and PDSCH.
[0018] In existing LTE TDD solutions, the UE is required to meet
pre-defined SI reading requirements, which are specified and
applicable under static TDD configuration. In this case the same
TDD configuration is used in all cells on the serving and
non-serving carriers over the entire period (T0) during which the
SI is acquired by the UE.
[0019] In order to ensure certain minimum serving cell performance
the pre-defined SI reading requirements also require the UE to send
at least certain number of ACK/NACK during T0 in response to
continuous DL data transmission. In static TDD the HARQ timing is
fixed and the requirement in terms of the number of ACK/NACK to be
transmitted is also fixed and depends on the TDD configuration.
[0020] However, in a system with flexible subframe operation such
as in dynamic TDD or in HD-FDD the direction of subframe can change
quickly, sometimes as fast as every radio frame. In this case, the
UE behavior in terms of transmitting the minimum number of ACK/NACK
during T0 is unspecified. This means that with flexible subframe
operation the UE will not be compliant to any requirements, thus
leading to one or more of the following problems: [0021]
degradation of serving cell performance in terms of receiving and
transmitting data during the SI acquisition; [0022] loss of
scheduling grant sent by the network node since UE may not be able
to use it; and [0023] degradation in SI reading performance or
failure to acquire the SI in case the UE creates fewer than
necessary autonomous gaps during T0.
SUMMARY
[0024] An object may be to alleviate or at least reduce one or more
of the above-mentioned problems. This object and others are
achieved by methods, the wireless device and the network node
according to the independent claims, and by the embodiments
according to the dependent claims.
[0025] According to a first aspect, the object is achieved by a
method, performed by a wireless device or User Equipment (UE), for
managing UL feedback during system information acquisition when
flexible subframe operation is configured. A method, performed in
the wireless device located in a first cell operated by a network
node of a wireless communication system is provided, and comprises
acquiring system information of a second cell using at least one
autonomous gap during a time period. The wireless device is
configured with a flexible subframe allocation scheme in the first
cell during at least a part of the time period. The method further
comprises obtaining a value Nmin corresponding to a minimum number
of UL feedback signals, where the value Nmin is associated with the
flexible subframe allocation scheme. The method also comprises
transmitting at least the minimum number Nmin of UL feedback
signals in response to DL data during the time period.
[0026] According to a second aspect, the object is achieved by a
wireless device which, when located in a first cell operated by a
network node of a wireless communication system, is configured to
acquire system information of a second cell using at least one
autonomous gap during a time period. The wireless device is
configured with a flexible subframe allocation scheme in the first
cell during at least a part of the time period. The wireless device
is also configured to obtain a value Nmin corresponding to a
minimum number of UL feedback signals, where the value Nmin is
associated with the flexible subframe allocation scheme. The
wireless device is further configured to transmit at least the
minimum number Nmin of UL feedback signals in response to DL data
during the time period.
[0027] According to a third aspect, the object is achieved by a
method, performed by a network node, for assisting a wireless
device to manage UL feedback during system information acquisition
when flexible subframe operation is configured. A method performed
in the network node of a wireless communication system operating a
first cell is provided. A wireless device is served by the first
cell. The method comprises transmitting configuration information
to the wireless device configuring the wireless device to operate
with a flexible subframe allocation scheme in the first cell during
at least part of a time period during which the wireless device
acquires system information of a second cell. The method also
comprises obtaining a value Nmin associated with the flexible
subframe allocation scheme, the value Nmin corresponding to a
minimum number of UL feedback signals that the wireless device
shall transmit in response to DL data during the time period. The
method further comprises transmitting DL data to the wireless
device in the first cell during the time period, and receiving at
least the minimum number Nmin of UL feedback signals in the first
cell in response to the transmitted DL data.
[0028] According to a fourth aspect, the object is achieved by a
network node for a wireless communication system configured to
operate a first cell. A wireless device is served by the first
cell. The network node is further configured to transmit
configuration information to the wireless device configuring the
wireless device to operate with a flexible subframe allocation
scheme in the first cell during at least part of a time period
during which the wireless device acquires system information of a
second cell. The network nodes is also configured to obtain a value
Nmin associated with the flexible subframe allocation scheme, the
value Nmin corresponding to a minimum number of UL feedback signals
that the wireless device shall transmit in response to DL data
during the time period. Further, the network node is configured to
transmit DL data to the wireless device in the first cell during
the time period, and receive at least the minimum number Nmin of UL
feedback signals in the first cell in response to the transmitted
DL data.
[0029] According to further aspects, the object is achieved by
computer programs and computer program products corresponding to
the aspects above.
[0030] An advantage of the different aspects above is that the
serving cell performance is guaranteed during the time period when
the UE acquires system information even if flexible subframe
configuration is used. The performance is guaranteed in terms of a
certain minimum number of DL subframes in which the UE can receive
data from the serving cell.
[0031] Another advantage of the different aspects above is that the
UE behavior in terms of the capability of transmitting minimum
number of ACK/NACK in response to continuous DL data transmission
is specified and is clear during the time period when the UE
acquires SI even if flexible subframe configuration is used.
[0032] Other advantages are that the network node may better
utilize the scheduling grant when the UE acquires the SI of a cell,
the acquisition of the SI of the second cell may be accurately
performed during a pre-defined time, and the UE is enabled to
create only necessary number of autonomous gaps for acquiring SI
during the time period.
BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The various aspects of embodiments disclosed herein,
including particular features and advantages thereof, will be
readily understood from the following detailed description and the
accompanying drawings.
[0034] FIG. 1a is a schematic illustration of a dynamic TDD
configuration made from two legacy TDD configurations.
[0035] FIG. 1b is a schematic illustration of an exemplifying
wireless communications system 100 in which embodiments herein may
be implemented.
[0036] FIG. 2 is a flowchart schematically illustrating an
exemplifying method according to embodiments.
[0037] FIG. 3a is a flowchart illustrating an exemplifying method
in the wireless device according to some embodiments of the present
invention.
[0038] FIG. 3b is a block diagram schematically illustrating the
wireless device according to some embodiments of the present
invention.
[0039] FIG. 4a is a flowchart illustrating an exemplifying method
in the network node according to some embodiments of the present
invention.
[0040] FIG. 4b is a block diagram schematically illustrating the
wireless device according to some embodiments of the present
invention.
[0041] FIGS. 5a-b are flowcharts illustrating the method in the
wireless device according to some embodiments of the present
invention.
[0042] FIGS. 6a-b are flowcharts illustrating the method in the
network node according to some embodiments of the present
invention.
[0043] FIGS. 7a-b are block diagrams schematically illustrating the
wireless device and the network node respectively according to some
embodiments of the present invention.
DETAILED DESCRIPTION
[0044] In embodiments of the invention, the problem of degraded
serving cell performance in terms of receiving and transmitting
data during the SI acquisition, which occurs when a wireless device
is configured with a flexible subframe allocation scheme, is
addressed by a solution where the wireless device transmits at
least a minimum number Nmin of UL feedback signals in response to
DL data in the time period during which the wireless device
acquires the SI. The value Nmin is associated with the flexible
subframe allocation scheme that the wireless device is configured
with and can thus be obtained by the wireless device as well as by
the network node serving the wireless device. The value Nmin may
thus be set such that the serving cell performance can be
guaranteed at a certain level. The performance is guaranteed in
terms of a certain minimum number of DL subframes in which the UE
can receive data from the serving cell in the time period during
which the wireless device uses autonomous gaps to acquire SI of
another cell.
[0045] In order to further explain the problem of prior art, it is
noted that according to TS 36.133 Rel-12, version 12.2.0, the UE
shall identify and report the CGI when requested by the network for
measurement with the purpose of `reportCGI`. The UE may make
autonomous gaps in DL reception and UL transmission for receiving
MIB and SIB1 messages.
[0046] The following may be concluded from section 8.1.2.2.4 of TS
36.133 "E-UTRA TDD intra-frequency measurement with autonomous
gap": In case of intra-frequency measurement the UE may be required
to be able to identify a new CGI of an E-UTRA cell within
T.sub.identify.sub._.sub.CGI,
intra=T.sub.basic.sub._.sub.identify.sub._.sub.CGI, intra, where
T.sub.basic.sub._.sub.identify.sub._.sub.CGI, intra=150 ms. This
means that the Reference Signal Received Power (RSRP) may be
required to fulfill certain side conditions. In addition to the
above requirements on the maximum time for identifying the CGI and
on the fulfilment of side conditions for the RSRP, a UE is required
to transmit a certain number of ACK/NACK during
T.sub.identify.sub._.sub.CGI, intra ms. This number depends on the
TDD UL/DL configuration and is shown in Table 2 in the background
section.
[0047] However in dynamic TDD, different radio frames may have
different TDD configurations and therefore the above requirement
that the UE has to transmit a number of ACK/NACK during
T.sub.identify.sub._.sub.CGI, intra ms that depends on the TDD
UL/DL configuration cannot apply. Therefore, in the case of dynamic
TDD, the requirement on how many ACK/NACK the UE has to transmit
during T.sub.identify.sub._.sub.CGI, intra ms, will be to transmit
at least the number of ACK/NACKs that is related to the TDD
configuration with the minimum number of DL subframes which is the
TDD configuration 0 (see Table 1 in the background section).
Therefore in case of dynamic TDD the UE shall be able to transmit
at least 18 ACK/NACKs, which is indicated as the minimum number of
ACK/NACKs for TDD configuration 0 in Table 2 of the background
section. The conclusion is that in case of dynamic TDD, for
intra-frequency measurements with autonomous gap, the UE shall be
able to transmit at least 18 ACK/NACKs during
T.sub.identify.sub._.sub.CGI, intra ms.
[0048] Similarly to intra-frequency measurement with autonomous
gap, the following may be concluded from section 8.1.2.3.6 and
8.1.2.3.7 of TS 36.133: "TDD-TDD and TDD-FDD inter-frequency
measurement with autonomous gap", for inter-frequency measurements.
If autonomous gaps are used for measurement with the purpose of
`reportCGI`, the UE shall be able to identify a new CGI of E-UTRA
cell within T.sub.identify.sub._.sub.CGI,
inter=T.sub.basic.sub._.sub.identify.sub._.sub.CGI, inter ms, where
T.sub.basic.sub._.sub.identify.sub._.sub.CGI, inter=150 MS.
[0049] This means that the RSRP may be required to fulfill certain
side conditions. In addition to the above requirements on the
maximum time for identifying the CGI and on the fulfillment of side
conditions for the RSRP, a UE is required to transmit 30 ACK/NACK
during T.sub.identify.sub._.sub.CGI, inter ms. This requirement has
been set based on TDD configuration 1 as it is a common
configuration. However in dynamic TDD different radio frames may
have different TDD configurations and therefore the above
requirement based on TDD configuration 1 cannot apply. Therefore,
in the case of dynamic TDD, the requirement on how many ACK/NACK
the UE has to transmit during T.sub.identify.sub._.sub.CGI, inter
ms, will be to transmit at least the number of ACK/NACKs that is
related to the TDD configuration with the minimum number of DL
subframes which is the TDD configuration 0 (see Table 1 in the
background section). Therefore in case of dynamic TDD the UE shall
be able to transmit at least 18 ACK/NACKs, which is indicated as
the minimum number of ACK/NACKs for TDD configuration 0 in Table 2
of the background section. The conclusion is that in case of
dynamic TDD, and for TDD-TDD and TDD-FDD inter-frequency
measurements with autonomous gap, the UE shall be able to transmit
at least 18 ACK/NACKs during T.sub.identify.sub._.sub.CGI, inter
ms.
[0050] Hence, in example embodiments relating to Radio Resource
Management (RRM) requirements for Enhanced Interference Mitigation
& Traffic Adaptation (eIMTA), where eIMTA is a flexible TDD
subframe allocation scheme that has been defined by 3GPP, the
following conclusions have been made:
[0051] In case of dynamic TDD, for intra-frequency measurements
with autonomous gap, the UE shall be able to transmit at least 18
ACK/NACKs (as an example of Nmin) during
T.sub.identify.sub._.sub.CGI, intra ms.
[0052] In case of dynamic TDD, for TDD-TDD and TDD-FDD
inter-frequency measurements with autonomous gap, the UE shall be
able to transmit at least 18 ACK/NACKs (as an example of Nmin)
during T.sub.identify.sub._.sub.CGI, inter ms.
[0053] Throughout the following description similar reference
numerals have been used to denote similar elements, units, modules,
circuits, nodes, parts, items or features, when applicable. In the
figures, features that appear only in some embodiments are
indicated by dashed lines.
[0054] FIG. 1b depicts an exemplifying wireless communications
system 100 in which embodiments herein may be implemented. In this
example, the wireless communications system 100 is an LTE system.
In other examples, the wireless communication system may be any
3GPP wireless communication system, such as a Universal Mobile
Telecommunication System (UMTS), Wideband Code Division Multiple
Access (WCDMA) network, a Global System for Mobile communication
(GSM) or the like. The wireless communication system 100 may even
be an evolution of any one of the aforementioned systems or a
combination thereof. Furthermore, the embodiments are described
when the UE is configured to be served by a single carrier, also
known as single carrier operation, or configured to use single
carrier in a network node. However the embodiments are also
applicable for multi-carrier or carrier aggregation operation.
[0055] The wireless communication system 100 comprises a network
node 120, referred to as a first network node herein. As used
herein, the term "network node" may refer to a radio network node,
a Base Station (BS), a Base Transceiver Station (BTS), a Radio Base
Station (RBS), a Remote Radio Unit (RRU) or a Remote Radio Head
(RRH), an access point, a NodeB in so called Third Generation (3G)
networks, evolved Node B, eNodeB or eNB in LTE networks, a relay
node, a donor node controlling a relay, transmission points or
nodes, nodes in a distributed antenna system (DAS), a core network
node, or the like. In UMTS Terrestrial Radio Access Network (UTRAN)
networks, the term "radio network node" may also refer to a Radio
Network Controller. Furthermore, in Global System for Mobile
Communications (GSM) EDGE Radio Access Network (GERAN), where EDGE
is short for Enhanced Data rates for GSM Evolution, the term "radio
network node" may also refer to a Base Station Controller
(BSC).
[0056] The network node 120 may operate a first cell 101, such as a
macro cell, a micro cell, a pico cell, a femto cell.
[0057] Furthermore, a wireless device 110 is located in the first
cell 101. Expressed differently, the wireless device 110 may be
associated with the first cell 101. This means that the wireless
device 110 may be connected to, or served by the first cell 101, or
the wireless device 110 may camp on the first cell 101.
[0058] As used herein, the term "wireless device" may refer to a
UE, a subscriber unit, mobile phone, a cellular phone, a Personal
Digital Assistant (PDA) equipped with radio communication
capabilities, a smartphone, a laptop or personal computer (PC)
equipped with an internal or external mobile broadband modem, a
tablet PC with radio communication capabilities, a portable
electronic radio communication device, a sensor device equipped
with radio communication capabilities or the like. The sensor may
be any kind of weather sensor, such as wind, temperature, air
pressure, and humidity. As further examples, the sensor may be a
light sensor, an electronic switch, a microphone, a loudspeaker,
and a camera sensor. Sometimes, the term "user", or "subscriber",
may be used to refer to the wireless device.
[0059] Furthermore, the wireless communication system 100 comprises
a second cell 102. The second cell 102 may be operated by the first
network node 120 or by a further network node 130, referred to as a
second network node herein. Hence, more generally, the wireless
communication system comprises a cell, which may be the first cell
101 or the second cell 102 depending on whether the cell is
operated by the network node 120 or the further network node 130.
In some example, both the first and second cells 101, 102 are
operated by the network node 120. The first network node is
typically the serving network node of the wireless device, and the
second network node may be a neighbouring network node from which
the wireless device can receive signals and/or obtain
information.
[0060] An exemplifying method in a UE served by the first network
node may comprise one or more of the following steps: [0061]
Acquiring SI of a cell during a time period, such as a pre-defined
time period, e.g. T0, which is applicable for flexible subframe
allocation. At least during part of the time period T0, the UE is
configured with or is operating with at least one flexible subframe
allocation scheme; [0062] Obtaining a minimum number (Nmin) of UL
feedback signals (e.g. ACK/NACK), where the Nmin value may be
determined based on pre-defined information or on information
received from the first network node. The UE should preferably
transmit the minimum number Nmin of UL feedback signals in response
to at least continuous transmission of DL data on e.g. PDSCH to the
UE by the first network node during the time period (e.g. T0). Nmin
is associated with the configured flexible subframe allocation;
[0063] Transmitting the minimum number (Nmin) of UL feedback
signals in response to at least continuous transmission of DL data
to the UE by the first network node during the time period (e.g.
T0); and [0064] Using the acquired SI for one or more radio
operations e.g. signaling to the first network node.
[0065] An exemplifying method in the first network node serving the
UE may comprise one or more of the following steps: [0066]
Configuring the UE with at least one flexible subframe allocation
scheme (e.g. dynamic or flexible TDD, HD-FDD operations); [0067]
Configuring the UE to acquire the SI of at least one cell during a
time period, such as a pre-defined time period (e.g. T0), which is
applicable for flexible subframe allocation; [0068] Transmitting DL
data e.g. on PDSCH to the UE in all the DL subframes during the
time period (e.g. T0). [0069] Receiving at least a minimum number
(Nmin) of UL feedback signals in response to the continuous
transmission of the DL data to the UE during the time period (e.g.
T0). Nmin is associated with the configured flexible subframe
allocation scheme.
[0070] In a dynamic UL/DL subframe allocation (e.g. dynamic TDD
system or HD-FDD operation), a group of subframes are fixed
subframes, while others are flexible subframes. Fixed subframes are
either UL subframes in all radio frames or DL subframes in all
radio frames. Flexible subframes can be UL subframes in some radio
frames and DL subframes in other radio frames. The assignment of
the UL or DL direction is done in a dynamic manner. The serving
cell performance can be expressed in terms of number of subframes
in which the UE can receive and/or transmit in its serving cell(s).
The UE may create autonomous gaps for acquiring SI of a cell.
However, when the UE creates autonomous gaps the dynamic UL/DL
subframe allocation makes the performance of serving cell
performance even more unpredictable. This problem is solved by at
least some embodiments herein. Hence, the embodiments herein
improve system performance.
[0071] FIG. 2 illustrates an exemplifying method according to
embodiments herein when performed in connection with the wireless
communication system 100 of FIG. 1b.
[0072] One or more of the following actions, or steps, may be
performed in any suitable order.
[0073] Action 201
[0074] The first network node 120 may configure the UE with at
least one flexible subframe. The at least one flexible subframe may
be included in a flexible subframe configuration scheme, which may
be applicable during a time period, e.g. during the time period T0
as described in the background section. The time period may be
given by DCI as mentioned in the background section. The action 201
may be performed by the configuring module 1020 in FIG. 4b.
[0075] Action 202
[0076] The first network node 120 may configure, or order/command,
the wireless device to acquire SI according to known manners. In
response to this action, the wireless device may create autonomous
gaps, which may cause the wireless device to miss some of the DL
data, or UL data when applicable, sent in action 208. But if UE is
scheduled only in DL then it will miss DL data and if UE is
scheduled only in UL then it will miss UL data. However, as
explained in section "Method in a network node of adapting
scheduling during SI acquisition under flexible subframe operation"
the missing of the DL data may be avoided. The action 202 may be
performed by the configuring module 1020 in FIG. 4b.
[0077] Action 203
[0078] The wireless device 110 may obtain, e.g. receive,
information about that it shall obtain SI, e.g. for the second cell
and/or for the first cell. The action 203 may be performed by the
obtaining module 820 in FIG. 3b.
[0079] Action 204
[0080] The first network node 120 may further configure the
wireless device with information about minimum UL feedback. The
information about minimum UL feedback may specify in which
subframes the wireless device shall send UL feedback, e.g. HARQ
feedback such as ACK/NACK. The information about minimum UL
feedback may be a minimum number of UL feedback signals and/or
subframes corresponding thereto. Moreover, the information about
minimum UL feedback may be associated with the flexible subframe
configuration scheme, e.g. UL/DL configuration. This action may be
performed by the configuring module 1020 in FIG. 4b.
[0081] In this manner, the wireless device and the first network
node may obtain common understanding of HARQ timing, i.e. when UL
feedback is sent from the wireless device.
[0082] Action 205a and/or 205b
[0083] The first network node 120 sends SI to the wireless device
and/or the second network node 130 sends SI to the wireless
device.
[0084] Action 206
[0085] The wireless device 110 receives SI from the first network
node. Alternatively, the wireless device 110 may receive SI from
the second network node 130 (alternative not shown in FIG. 2).
[0086] Action 207
[0087] The wireless device 110 obtains the minimum (min) UL
feedback. The minimum UL feedback may be associated with the
applied, or configured, at least one flexible subframe as in action
201. Thus, the minimum UL feedback may be associated with the
flexible subframe configuration scheme, such as UL/DL
configuration.
[0088] In some examples, the min UL feedback may be configured by
the first network node as in action 204. The min UL feedback may
e.g. be sent from the first network node.
[0089] In some examples, the min UL feedback may be determined by
the wireless device according to various manners as described in
bullet 4, in section "Method in a UE of adapting serving cell
performance during SI acquisition under flexible subframe
operation". This action 207 may be performed by the determining
module 840 in FIG. 3b.
[0090] The first network node may be aware of how the wireless
device performs action 207. In this way, the first network node and
the wireless device obtain a common understanding of when and/or
how UL feedback is to be sent from the wireless device.
[0091] Action 208
[0092] The first network node 120 sends DL data to the wireless
device.
[0093] Action 209
[0094] The wireless device 110 receives the DL data from the first
network node 120 (see action 208).
[0095] Action 210
[0096] In response to the reception of the DL data, the wireless
device 110 sends UL feedback.
[0097] Action 211
[0098] The first network node 120 receives the UL feedback from the
wireless device (see action 210).
[0099] Action 212
[0100] The wireless device 110 may use the received SI in various
manner, e.g. in order to measure on the second cell as a
preparation before a handover.
[0101] Action 213
[0102] The network node 120 may receive e.g. a measurement report,
where the measurement report is based on the measurements of the
wireless device in action 212.
Method in a UE of Adapting Serving Cell Performance During SI
Acquisition Under Flexible Subframe Operation
[0103] This embodiment describes a method implemented in a UE
operating in a first cell which is served, or operated, by a first
network node, wherein the UE acquires the SI of at least one second
cell which is served, or operated, by the second network node and
wherein the UE is also configured to operate with flexible subframe
allocation scheme, e.g. dynamic or flexible TDD or HD-FDD
operations. The flexible subframe allocation scheme is used in at
least one first cell from which the UE receives and/or transmits
data. The first cell is the serving cell or at least one of the
serving cells of the UE configured with a plurality of serving
cells for multi-carrier operation. The serving cell may also be
interchangeably called a PCell (primary cell). An SCell (secondary
cell) is also a serving cell in multi-carrier operation. The
flexible subframe allocation scheme may also be used in other cells
e.g. one or more neighbouring cells on intra-frequency and/or
non-serving carrier frequencies. The first and second cells may
operate on the same carrier frequency (intra-frequency cells), on
different carrier frequencies of the same RAT (inter-frequency
cells), on the same frequency of different RATs, or on different
carrier frequencies of different RATs. As a special case the first
and the second cells can be the same, e.g. when the UE acquires the
SI of the serving cell. The steps performed in the UE may comprise
one or more of:
[0104] 1. Obtaining information that SI of at least one second cell
is to be acquired. The SI may comprise one or more of MIB, SIB1 or
any other SIB (e.g. SIB2, SIBS). The information can be obtained
based on a request received from the first network node or it can
be decided internally by the UE. An example of a received request
can be an RRC message containing one or more of `reportCGI` or
`report CSG indicator` or `reporting SI`, where a CSG is a Closed
Subscriber Group. The term `acquisition of SI or acquiring SI` may
also be called `SI reading or reading of SI`, `identifying or
identification of SI`, `determining SI` etc. This action is similar
to action 203.
[0105] 2. Creating autonomous gaps for acquiring the SI of the at
least one second cell based on the obtained information. The
autonomous gaps are created for use during a pre-defined duration
(e.g. T0, or another time period). The pre-defined duration or time
period may also be referred to as a time needed to identify CGI of
a cell, or a time needed to acquire SI of a cell. During autonomous
gaps the UE serving operation is interrupted. This implies that
during such gaps the UE in the serving cell (i.e. in the first
cell) may not transmit any signal in UL and may not receive any
signal in DL. This means that the UE cannot be served in UL and DL
by its serving cell during such gaps. This action may be performed
in response to action 202. Therefore, this action may be part of
action 203 above.
[0106] 3. Determining that the UE is configured to operate with a
flexible subframe allocation scheme in at least one serving cell
during at least part of T0. This action may be part of action 207
above. The determination of the scheme can be based on
configuration received from the first network node and/or based on
a UE radio access capability associated with the flexible subframe
allocation scheme supported by the UE. The flexible subframe
allocation scheme may comprise one of:
[0107] a. Flexible or dynamic TDD configuration, which apply at
least partly during the time period (e.g. T0). The flexible TDD
configuration may involve one or more of the following:
[0108] i. At least one subframe changes between any two of UL
subframe, DL subframe and special subframe;
[0109] ii. A number of subframes and/or allocation in time of at
least one subframe is different during two different radio
frames;
[0110] iii. At least two different TDD UL/DL configurations are
configured or indicated by the first network node for use by the
UE;
[0111] iv. At least two different TDD UL/DL configurations are used
by the UE.
[0112] b. Flexible subframe operation in HD-FDD, which apply at
least partly during the time period (e.g. T0). The flexible
subframe operation in HD-FDD may involve one or more of the
following:
[0113] i. At least one subframe changes between any two of UL
subframe, DL subframe and unused subframe;
[0114] ii. A number of subframes and/or allocation in time of at
least one subframe is different during two different radio
frames;
[0115] iii. At least two different subframe configurations, also
known as HD-FDD configurations or HD-FDD subframe configurations,
are configured or indicated by the first network node for use by
the UE;
[0116] iv. At least two different subframe configurations are used
by the UE.
[0117] 4. Obtaining (or determining) a minimum number (Nmin) of UL
feedback signals that the UE preferably should transmit in response
to at least continuous transmission of DL data (e.g. PDSCH) to the
UE by the first network node during the time period (e.g. T0). The
minimum number Nmin is associated with the determined flexible
subframe allocation scheme. The continuous transmission of DL data
herein means that the first network node transmits data in all the
DL subframes during the SI acquisition time, that is e.g. over T0.
The minimum number Nmin may be applicable under or associated with
additional conditions or constraints. These additional conditions
or constraints may comprise one or more of that during at least
part of T0 when the UE is NOT configured with a measurement gap,
the UE is NOT configured with any DRX cycle, the UE is not
operating in DRX, the UE is configured to receive DL data from the
first network node with a pre-defined number of code words in one
subframe (e.g. 1 code word per subframe), and no Multicast
Broadcast Single Frequency Network (MBSFN) subframe is configured
in the serving cell or PCell. Examples of subframes which can be
configured as MBSFN subframes are subframes #1, 2, 3, 6, 7 and 8
for FDD and subframes #3, 4, 7, 8 and 9 for TDD. This action is
similar to action 207 above.
[0118] a. Example of pre-defined number of code words is 1 code
word. Examples of UL feedback signals are:
[0119] i. Any UL signal which is sent by the UE as part of HARQ
feedback for acknowledging the reception of DL channels e.g.
reception of PDSCH from the first network node.
[0120] ii. More specifically the number of ACK/NACK transmitted by
the UE as part of HARQ feedback. For example one ACK or NACK
corresponds to DL transmission with single or one code word. For
example in 10 subframes with DL transmission with one code word per
frame the Nmin is also ten ACK/NACK.
[0121] b. The minimum number Nmin can be obtained by any one or
more of the following means:
[0122] c. Information (i.e. the minimum number value Nmin) received
from the first network node;
[0123] d. Pre-defined minimum number, Nmin, specified in the
standard. In this case the Nmin is stored in the memory of the
UE;
[0124] e. Pre-defined rule, expression or function used to derive
Nmin. Examples of such rules and functions are that when flexible
subframe allocation is used at least partly during the time period
(e.g. T0) then:
[0125] i. The UE shall assume that Nmin is equal to the number of
ACK/NACK used for certain reference or pre-defined subframe
configuration, wherein a subframe configuration comprises of any
combination of DL, UL, unused, special subframes per frame. For
example, Nmin may be the number of ACK/NACK when using any of
HD-FDD configuration assuming only two DL subframes per frame, TDD
configuration with certain number of DL subframe per frame (e.g.
two DL per frame), or TDD configuration #0 (i.e. 18 ACK/NACK).
[0126] ii. The UE shall assume that Nmin is equal to the lowest
number of ACK/NACK out of ACK/NACKs corresponding to all possible
(i.e. pre-defined) subframe configurations, e.g. out of TDD
configurations #0 to #6.
[0127] The UE shall assume that Nmin is equal to the lowest number
of ACK/NACK out of ACK/NACKs corresponding to all pre-configured
subframe configurations e.g. out of TDD configurations #0, #1 and
#4.
[0128] iv. The UE shall derive the minimum number value Nmin based
on a function of plurality of number of ACK/NACK corresponding to
at least two subframe configurations. Examples of functions are
minimum, maximum, mean, and the Xth percentile. It may for example
be assumed that the number of ACK/NACK corresponding to TDD
configurations #1 and #6 are 35 and 30 respectively. By applying
the minimum function, the UE shall derive Nmin=30 ACK/NACK, which
it has to transmit during the time period (e.g. T0) under
continuous DL data allocation/transmission by the first network
node.
[0129] v. The UE shall derive the minimum number value Nmin based
on a function of a plurality of number of ACK/NACK corresponding to
all the pre-defined subframe configurations.
[0130] vi. The UE shall derive the minimum number Nmin based on a
function of a plurality of number of ACK/NACK corresponding to at
least the subframe configurations configured by the first network
node for use by the UE during T0.
[0131] vii. The UE shall derive the minimum number, Nmin, based on
a function of a plurality of number of ACK/NACK corresponding to at
least the subframe configurations used by the UE during T0.
[0132] viii. The UE shall derive the minimum number Nmin as a
function of: the minimum number Nmin_ref specified for the scenario
without flexible subframe configuration and a degradation with
respect to Nmin_ref. Examples of the degradation are: [0133]
Nmin=Nmin_ref-N, where N is the number of ACK/NACK that may be lost
due to using flexible subframe configuration; in another example, N
may also depend on the exact subframe configurations that are
flexible such as the number of DL or UL subframes; [0134]
Nmin=Nmin_ref*r0 or Nmin=Nmin_ref*(1-r1) or
Nmin=Nmin_ref*(100%-r2)/100%, where r1 (e.g., 0.1) and r2 (e.g.,
2%) are relative degradations, and r0 (0<r0<1) is a parameter
reflecting a degradation.
[0135] 5. Acquiring the SI of the at least one second cell using
autonomous gap during the time period (e.g. T0) based at least on
the obtained information in step 1. This action is similar to
action 206.
[0136] 6. Transmitting the minimum number Nmin of UL feedback
signals in response to or corresponding to the continuous
transmission of DL data by the first network node to the UE during
the time period (e.g. during T0). This action is similar to action
210.
[0137] 7. Using the acquired SI information for one or more radio
operations. This action is similar to action 212. Examples of radio
operations are: [0138] (a) Signaling the acquired SI to the first
network node or to another UE; [0139] (b) Signaling the acquired SI
to another UE if both UEs are capable of Device-to-Device (D2D)
operation or communication; [0140] (c) Storing the acquired SI in
the memory for use at future time. In one example the stored data
is reported to the network node as part of the minimization of
drive test (MDT) or self-organizing network (SON); [0141] (d)
Comparing the acquired CGI in the SI with the PCI of the second
cell for verifying or confirming the identification of the second
cell.
[0142] It should be noted that the steps 1-7 explained above are
not necessarily done in the order that is presented here. For
example it can be that step 3, which is the determining that the UE
is configured to operate with a flexible subframe allocation
scheme, is done before steps 1 and 2.
Method in a Network Node of Assisting the UE to Adapt Serving Cell
Performance During SI Acquisition Under Flexible Subframe
Operation
[0143] This embodiment describes a method implemented in a first
network node operating a first cell and serving a UE. The UE
acquires the SI of at least one second cell which is served by the
second network node. The first network node configures the UE to
operate with flexible subframe allocation scheme e.g. dynamic or
flexible TDD, or HD-FDD operations. The flexible subframe
allocation scheme is used in at least one first cell from which the
UE receives and/or transmits data. The first cell is the serving
cell or at least one of the serving cells of the UE configured with
plurality of serving cells for multi-carrier operation. The serving
cell may interchangeably be referred to as a PCell. SCell is also a
serving cell in multi-carrier operation. The flexible subframe
allocation scheme may also be used in other cells, e.g. in one or
more neighbouring cells on intra-frequency and/or non-serving
carrier frequencies. The first and second cells may operate on the
same carrier frequency (intra-frequency cells), on different
carrier frequencies of the same RAT (inter-frequency cells), on the
same frequency of different RATs, or on different carrier
frequencies of different RATs. As a special case the first and the
second cells can be the same, e.g. when the UE acquires the SI of
the serving cell. The steps performed in the first network node
comprise one or more of the following:
[0144] 1. Configuring the UE to operate with at least one flexible
subframe allocation scheme in at least one serving cell. The scheme
may e.g. comprise dynamic or flexible TDD, or HD-FDD operations, as
described in Step 3 of the section "Method in a UE of adapting
serving cell performance during SI acquisition under flexible
subframe operation". This action is similar to action 201.
[0145] 2. Requesting or configuring the UE to report CGI or acquire
SI of at least one second cell. This action is similar to action
202.
[0146] 3. Configuring (optionally) the UE with the minimum number
(Nmin) of UL feedback signals that the UE preferably should
transmit in response to at least continuous transmission of DL data
(e.g. PDSCH) to the UE by the first network node during the time
period (e.g. T0). The minimum number Nmin is associated with the
determined flexible subframe allocation scheme. Prior to
configuring the UE with Nmin, the first network node may also
determine the Nmin. In one example the first network node may also
configure the UE with the Nmin corresponding to the amount of data
that the first network node has to transmit to the UE during the
time period, e.g. T0. This can be determined by observing the
amount of data for the UE in the buffer. In another example the
Nmin can be determined based on one or more of a pre-defined rule,
an expression, or a function, as described in Step 4 of section
"Method in a UE of adapting serving cell performance during SI
acquisition under flexible subframe operation". This action is
similar to action 204.
[0147] 4. Transmitting continuously DL data (e.g. PDSCH) to the UE
during the time T0. The continuous DL data transmission comprises
transmitting DL data channel in all DL subframes during the time
period (e.g. T0). This action is similar to action 208.
[0148] 5. Receiving at least the minimum number Nmin of UL feedback
signals transmitted by the UE in response to at least said
continuous transmission of DL data to the UE. The minimum number
Nmin of UL signals is equal to one of: the configured minimum
number of UL signals; a pre-defined minimum number specified in the
standard; and a pre-defined rule, expression or function as
described in Step 4 of section "Method in a UE of adapting serving
cell performance during SI acquisition under flexible subframe
operation". This action is similar to action 211.
[0149] 6. Receiving the measurement report from the UE containing
at least the acquired SI during the time period (e.g. T0). This
action is similar to action 213.
[0150] It should be noted that the steps explained above are not
necessarily done in the order that is presented here.
Method in a Network Node of Adapting Scheduling During SI
Acquisition Under Flexible Subframe Operation
[0151] This embodiment describes yet another method implemented in
a first network node for the same scenario mentioned in section
"Method in a network node of assisting UE to adapt serving cell
performance during SI acquisition under flexible subframe
operation". In this method, the network node adapts its scheduling
of data to the UE during at least T0, when the network node
configures the UE or plan to configure the UE to acquire the SI of
at least the second cell, while taking into account the following:
[0152] A minimum number (Nmin) of UL feedback signals that the UE
preferably should transmit in response to at least continuous
transmission of DL data (e.g. PDSCH) to the UE by the first network
node during the time period (e.g. T0). The minimum number Nmin is
associated with the determined flexible subframe allocation scheme.
[0153] That the UE is configured with at least one flexible
subframe allocation scheme and/or is operating with at least one
flexible subframe allocation scheme during at least part of T0.
[0154] Examples of adaptation of scheduling are: [0155] Scheduling
the UE for receiving data in number of subframes corresponding or
not exceeding to the minimum number (Nmin) of UL feedback signals
transmitted by the UE during the time period (e.g. T0). The Nmin
may be determined as described in Step 4 of section "Method in a UE
of adapting serving cell performance during SI acquisition under
flexible subframe operation" and in Steps 3 and 4 of section
"Method in a network node of assisting UE to adapt serving cell
performance during SI acquisition under flexible subframe
operation". [0156] Modifying one or more parameters of the flexible
subframe allocation scheme in order to increase the available
subframes, if the determined number of subframes in which the first
network node can schedule the UE during the time period (e.g. T0)
is below a threshold (e.g. less than 15 subframes). One example is
to use or configure the UE during the time period (e.g. T0) with
only those subframe configurations which have at least three or
more DL subframes per radio frame.
[0157] In one example embodiment, the network node schedules the
wireless device while taking the minimum number of UL feedback
signals into account. After adapting the scheduling scheme the
first network node may start scheduling the UE with DL data using
the adapted scheduling scheme.
Embodiments of Methods Described with Reference to FIGS. 5a and
5b
[0158] FIG. 5a is a flowchart illustrating one embodiment of the
method performed in the wireless device 110 located in the first
cell 101 operated by the network node 120 of the wireless
communication system 100. In one embodiment the wireless device 110
may be a UE located in a cell 101 of a E-UTRAN served by an eNodeB.
The network node 120 may thus be the eNodeB. The first cell 101 may
be a serving cell, a PCell in multi-carrier operation, or a SCell
in multi-carrier operation. The method comprises: [0159] 510:
Acquiring SI of a second cell using at least one autonomous gap
during a time period. The SI may comprise information uniquely
identifying the second cell. The time period has been referred to
as T0 previously. One example of the time period is the time period
specified in 3GPP TS 36.331 T.sub.identify.sub._.sub.CGI, intra ms.
The wireless device is configured with a flexible subframe
allocation scheme in the first cell during at least a part of the
time period. The wireless device may be configured with the
flexible subframe allocation scheme based on configuration
information received from the network node. The flexible subframe
allocation scheme may e.g. be a dynamic TDD or a HD-FDD subframe
allocation scheme. This step may correspond to action 206 described
above. [0160] 520: Obtaining a value Nmin corresponding to a
minimum number of uplink feedback signals. In one embodiment Nmin
may be 18, as described previously. The uplink feedback signals may
comprise acknowledgement and non-acknowledgement signals (ACK/NACK)
as part of HARQ feedback. The value Nmin is associated with the
flexible subframe allocation scheme. Obtaining the value Nmin may
comprise receiving information from the network node comprising the
value Nmin (see step 625 below). Alternatively, obtaining may
comprise retrieving the value Nmin stored in the wireless device,
or deriving the value Nmin based on a pre-defined rile, and
expression, or a function, as described above in bullet 4.e in the
section "Method in a UE of adapting serving cell performance during
SI acquisition under flexible subframe operation". [0161] 530:
Transmitting at least the minimum number Nmin of uplink feedback
signals in response to downlink data during the time period. The
uplink feedback signals may be transmitted in the first cell in
response to downlink data received from the network node in the
first cell. As described above, in case of dynamic TDD, and for
TDD-TDD and TDD-FDD inter-frequency measurements with autonomous
gap, the UE shall be able to transmit at least 18 ACK/NACKs during
T.sub.identffy.sub._.sub.CGI, intra ms. This step may correspond to
action 209 and 210 described above.
[0162] FIG. 5b is a flowchart illustrating another embodiment of
the method in the wireless device 110. The method comprises: [0163]
505: Receiving a request from the network node to report the SI of
the second cell. The SI may comprise information uniquely
identifying the second cell. This step may correspond to action 203
described above. [0164] 510: Acquiring SI of a second cell in
response to the request using at least one autonomous gap during a
time period. The wireless device is configured with a flexible
subframe allocation scheme in the first cell during at least a part
of the time period. The flexible subframe allocation scheme may
e.g. be a dynamic or flexible TDD subframe allocation scheme.
[0165] 520: Obtaining a value Nmin corresponding to a minimum
number of UL feedback signals. The value Nmin is associated with
the flexible subframe allocation scheme. [0166] 530: Transmitting
at least the minimum number Nmin of UL feedback signals in response
to downlink data during the time period. As described above, in
case of dynamic TDD, and for TDD-TDD and TDD-FDD inter-frequency
measurements with autonomous gap, the UE shall be able to transmit
at least 18 ACK/NACKs during T.sub.identify.sub._.sub.CGI, intra
ms. [0167] 540: Transmitting the acquired SI to the network node.
This step may correspond to action 212 described above.
[0168] FIG. 6a is a flowchart illustrating one embodiment of the
method performed in the network node 120 of the wireless
communication system 100 operating the first cell 101. The wireless
device 110 is served by the first cell 101. The first cell 101 may
be a serving cell, a PCell in multi-carrier operation, or a SCell
in multi-carrier operation. The method comprises: [0169] 610:
Transmitting configuration information to the wireless device,
configuring the wireless device to operate with a flexible subframe
allocation scheme in the first cell during at least part of a time
period during which the wireless device acquires SI of a second
cell. The SI may comprise information uniquely identifying the
second cell. The flexible subframe allocation scheme may be a
dynamic Time Division Duplex, TDD, or a Half Duplex Frequency
Division Duplex, HD-FDD subframe allocation scheme. This step may
correspond to action 201 described above. [0170] 620: Obtaining a
value Nmin associated with the flexible subframe allocation schem.
The value Nmin corresponds to a minimum number of UL feedback
signals that the wireless device shall transmit in response to
downlink data during the time period. The UL feedback signals may
comprise acknowledgement and non-acknowledgement signals (ACK/NACK)
as part of HARQ feedback. Obtaining the value Nmin may as described
for the wireless device above, be done in alternative ways.
Obtaining may comprise retrieving the value Nmin stored in the
network node, determining the value Nmin based on a pre-defined
rule, expression or function (as described above), or determining
the value Nmin based on an amount of data associated with the
wireless device in the buffer of the network node. [0171] 630:
Transmitting downlink data to the wireless device in the first cell
during the time period. This step may correspond to action 208
described above. [0172] 640: Receiving at least the minimum number
Nmin of UL feedback signals in the first cell in response to the
transmitted downlink data. This step may correspond to action 211
described above.
[0173] FIG. 6b is a flowchart illustrating another embodiment of
the method in the network node 120. The method comprises: [0174]
605: Transmitting a request to the wireless device to report the SI
of the second cell. The SI may comprise information uniquely
identifying the second cell. This step may correspond to action 202
described above. [0175] 610: Transmitting configuration information
to the wireless device, configuring the wireless device to operate
with a flexible subframe allocation scheme in the first cell during
at least part of a time period during which the wireless device
acquires SI of a second cell. [0176] 620: Obtaining a value Nmin
associated with the flexible subframe allocation scheme, the value
Nmin corresponding to a minimum number of UL feedback signals that
the wireless device shall transmit in response to downlink data
during the time period. [0177] 625: Transmitting information to the
wireless device comprising the value Nmin [0178] 630: Transmitting
downlink data to the wireless device in the first cell during the
time period. [0179] 640: Receiving at least the minimum number Nmin
of UL feedback signals in the first cell in response to the
transmitted downlink data. [0180] 650: Receiving SI of the second
cell from the wireless device.
[0181] As described in the section "Method in a network node of
adapting scheduling during SI acquisition under flexible subframe
operation", the method may in any of the above described
embodiments further comprise adapting a scheduling scheme for the
wireless device based on the minimum number of UL feedback signals
that the wireless device shall transmit in response to downlink
data during the time period, and scheduling the wireless device
using the adapted scheduling scheme. In another embodiment, the
method may comprise adapting one or more parameters of the flexible
subframe allocation scheme based on the minimum number of subframes
in which the wireless device can be scheduled with downlink data
during the time period. The configuration information transmitted
in 610 to the wireless device may then configure the wireless
device to operate with the adapted flexible subframe allocation
scheme.
Embodiments of Apparatus Described with Reference to FIGS. 7a-b
[0182] An embodiment of the wireless device 110 is schematically
illustrated in the block diagram in FIG. 7a. The wireless device
110 is configured to, when located in the first cell 101 operated
by the network node 120 of the wireless communication system 100,
acquire SI of a second cell using at least one autonomous gap
during a time period. The first cell may be a serving cell, a PCell
in multi-carrier operation, or a SCell in multi-carrier operation.
The wireless device is configured with a flexible subframe
allocation scheme in the first cell during at least a part of the
time period. The flexible subframe allocation scheme may be a
dynamic TDD or a HD-FDD subframe allocation scheme. The wireless
device is further configured to obtain a value Nmin corresponding
to a minimum number of UL feedback signals. The value Nmin is
associated with the flexible subframe allocation scheme. The UL
feedback signals may comprise acknowledgement and
non-acknowledgement signals (ACK/NACK) as part of HARQ feedback.
The wireless device is also configured to transmit at least the
minimum number Nmin of UL feedback signals in response to downlink
data during the time period.
[0183] In embodiments, the wireless device 110 may be further
configured to receive a request from the network node to report the
SI of the second cell, and to acquire the SI in response to the
request. The wireless device may be configured to acquire the SI
comprising information uniquely identifying the second cell. The
wireless device 110 may also be further configured to transmit the
acquired SI to the network node.
[0184] The wireless device may further be configured to transmit
the UL feedback signals in the first cell in response to downlink
data received from the network node in the first cell.
[0185] The wireless device may also be configured to obtain the
value Nmin by one of the following: receiving information from the
network node comprising the value Nmin; retrieving the value Nmin
stored in the wireless device; deriving the value Nmin based on a
pre-defined rule, expression or function.
[0186] In embodiments, the wireless device 110 is configured with
the flexible subframe allocation scheme based on configuration
information received from the network node.
[0187] In embodiments of the invention, the wireless device 110 may
comprise a processing module 710 and a memory 705 as illustrated in
FIG. 7a. The wireless device 110 may also comprise an input/output
(I/O) unit 704 configured to communicate with the network node 120
or another node of the communication system. The memory 705 may
contain instructions executable by said processing module 710
whereby the wireless device 110 is operative to acquire SI of a
second cell using at least one autonomous gap during a time period.
The wireless device is configured with a flexible subframe
allocation scheme in the first cell during at least a part of the
time period. The wireless device 110 may be further operative to
obtain a value Nmin corresponding to a minimum number of UL
feedback signals. The value Nmin is associated with the flexible
subframe allocation scheme. The wireless device 110 may also be
operative to transmit at least the minimum number Nmin of UL
feedback signals in response to downlink data during the time
period.
[0188] In an alternative way to describe the embodiment in FIG. 7a,
the wireless device 110 may comprise an acquiring module 711
adapted to acquire SI of a second cell using at least one
autonomous gap during a time period. The wireless device is
configured with a flexible subframe allocation scheme in the first
cell during at least a part of the time period. The wireless device
may be configured with the flexible subframe allocation scheme
based on configuration information received from the network node.
The flexible subframe allocation scheme may be a dynamic TDD or a
HD-FDD subframe allocation scheme. The first cell may be one of the
following: a serving cell, a PCell in multi-carrier operation, or a
SCell in multi-carrier operation. The wireless device 110 may also
comprise an obtaining module 712 adapted to obtain a value Nmin
corresponding to a minimum number of UL feedback signals. The value
Nmin is associated with the flexible subframe allocation scheme.
The uplink feedback signals may comprise acknowledgement and
non-acknowledgement signals as part of hybrid automatic
retransmission request feedback. The wireless device 110 may
further comprise a transmitting module 713 adapted to transmit at
least the minimum number Nmin of UL feedback signals in response to
downlink data during the time period.
[0189] Furthermore, the wireless device 110 may comprise a
receiving module adapted to receive a request from the network node
to report the system information of the second cell, wherein the
acquiring module 711 is adapted to acquire the system information
in response to the request. The transmitting module 713 may also be
adapted to transmit the acquired system information to the network
node. The system information may comprise information uniquely
identifying the second cell. The transmitting module 713 may
further be adapted to transmit the uplink feedback signals in the
first cell in response to downlink data received from the network
node in the first cell.
[0190] The obtaining module 712 may be adapted to obtain the value
Nmin by one of the following: receiving information from the
network node comprising the value Nmin; retrieving the value Nmin
stored in the wireless device; or deriving the value Nmin based on
a pre-defined rule, expression or function.
[0191] The modules described above are functional units which may
be implemented in hardware, software, firmware or any combination
thereof. In one embodiment, the modules are implemented as a
computer program running on a processor.
[0192] In still another alternative way to describe the embodiment
in FIG. 7a, the wireless device 110 may comprise a Central
Processing Unit (CPU) which may be a single unit or a plurality of
units. Furthermore, the wireless device 110 may comprise at least
one computer program product (CPP) 702 with a computer readable
medium 703 in the form of a non-volatile memory, e.g. an EEPROM
(Electrically Erasable Programmable Read-Only Memory), a flash
memory or a disk drive. The CPP 702 may comprise a computer program
701 stored on the computer readable medium 703, which comprises
code means which when run on the CPU of the wireless device 110
causes the wireless device 110 to perform the methods described
earlier in conjunction with FIGS. 5a-b. In other words, when said
code means are run on the CPU, they correspond to the processing
module 710 in FIG. 7a.
[0193] An embodiment of the network node 120 is schematically
illustrated in the block diagram in FIG. 7b. The network node 120
is configured to, operate the first cell 101. The wireless device
110 is served by the first cell 101. The first cell may be a PCell
in multi-carrier operation, or a SCell in multi-carrier operation.
The network node 120 is further configured to transmit
configuration information to the wireless device, configuring the
wireless device to operate with a flexible subframe allocation
scheme in the first cell during at least part of a time period
during which the wireless device acquires SI of a second cell. The
network node 120 is also configured to obtain a value Nmin
associated with the flexible subframe allocation scheme. The value
Nmin corresponds to a minimum number of UL feedback signals that
the wireless device shall transmit in response to downlink data
during the time period. The network node 120 is further configured
to transmit downlink data to the wireless device in the first cell
during the time period, and receive at least the minimum number
Nmin of UL feedback signals in the first cell in response to the
transmitted downlink data.
[0194] The network node 120 may be further configured to transmit a
request to the wireless device to report the SI of the second cell.
The network node 120 may also be configured to receive SI of the
second cell from the wireless device. The SI may comprise
information uniquely identifying the second cell. The network node
120 may be configured to obtain the value Nmin by retrieving the
value Nmin stored in the network node, by determining the value
Nmin based on a pre-defined rule, expression, or function, or by
determining the value Nmin based on an amount of data associated
with the wireless device in the buffer of the network node. The
network node 120 may be further configured to transmit information
to the wireless device comprising the value Nmin.
[0195] In embodiments, the network node 120 may be further
configured to adapt a scheduling scheme for the wireless device
based on the minimum number of UL feedback signals that the
wireless device shall transmit in response to downlink data during
the time period, and schedule the wireless device using the adapted
scheduling scheme. The network node 120 may also be configured to
adapt one or more parameters of the flexible subframe allocation
scheme based on the minimum number of subframes in which the
wireless device can be scheduled with downlink data during the time
period, and transmit configuration information to the wireless
device, configuring the wireless device to operate with the adapted
flexible subframe allocation scheme.
[0196] In embodiments of the invention, the network node 120 may
comprise a processing module 750 and a memory 795 as illustrated in
FIG. 7b. The network node 120 may also comprise an input/output
(I/O) unit 794 configured to communicate with the wireless device
or another node of the communication system. The memory 795 may
contain instructions executable by said processing module 750
whereby the network node 120 is operative to transmit configuration
information to the wireless device, configuring the wireless device
to operate with a flexible subframe allocation scheme in the first
cell during at least part of a time period during which the
wireless device acquires system information of a second cell. The
network node 120 may be further operative to obtain a value Nmin
associated with the flexible subframe allocation scheme. The value
Nmin corresponds to a minimum number of uplink feedback signals
that the wireless device shall transmit in response to downlink
data during the time period. The network node 120 may also be
operative to transmit downlink data to the wireless device in the
first cell during the time period. The network node 120 may further
be operative to receive at least the minimum number Nmin of uplink
feedback signals in the first cell in response to the transmitted
downlink data.
[0197] In an alternative way to describe the embodiment in FIG. 7b,
the network node 120 may comprise a first transmitting module 751
adapted to transmit configuration information to the wireless
device, configuring the wireless device to operate with a flexible
subframe allocation scheme in the first cell during at least part
of a time period during which the wireless device acquires system
information of a second cell. The flexible subframe allocation
scheme may be a dynamic TDD or a HD-FDD subframe allocation scheme.
The first cell may be one of the following: a serving cell, a PCell
in multi-carrier operation, or a SCell in multi-carrier operation.
The network node 120 may also comprise an obtaining module 752
adapted to obtain a value Nmin associated with the flexible
subframe allocation scheme. The value Nmin corresponds to a minimum
number of uplink feedback signals that the wireless device shall
transmit in response to downlink data during the time period. The
uplink feedback signals may comprise acknowledgement and
non-acknowledgement signals as part of hybrid automatic
retransmission request feedback.
[0198] The obtaining module 752 may be adapted to obtain the value
Nmin by one of the following: retrieving the value Nmin stored in
the network node; determining the value Nmin based on a pre-defined
rule, expression or function; or determining the value Nmin based
on an amount of data associated with the wireless device in the
buffer of the network node. The network node 120 may further
comprise a second transmitting module 753 adapted to transmit
downlink data to the wireless device in the first cell during the
time period. The network node 120 may further comprise a receiving
module 754 adapted to receive at least the minimum number Nmin of
uplink feedback signals in the first cell in response to the
transmitted downlink data. The modules described above are
functional units which may be implemented in hardware, software,
firmware or any combination thereof. In one embodiment, the modules
are implemented as a computer program running on a processor.
[0199] The transmitting modules 751 and 753 of the network node 120
may be further adapted to transmit a request to the wireless device
to report the system information of the second cell. The receiving
module 754 may be further adapted to receive system information of
the second cell from the wireless device. The system information
may comprise information uniquely identifying the second cell. The
transmitting modules 751 and 753 may be further adapted to transmit
information to the wireless device comprising the value Nmin.
[0200] The network node 120 may further comprise an adapting module
for adapting a scheduling scheme for the wireless device based on
the minimum number of uplink feedback signals that the wireless
device shall transmit in response to downlink data during the time
period, and a scheduling module for scheduling the wireless device
using the adapted scheduling scheme. The network node may also
comprise a further module for adapting one or more parameters of
the flexible subframe allocation scheme based on the minimum number
of subframes in which the wireless device can be scheduled with
downlink data during the time period, wherein the transmitting
modules 751 and 753 may be adapated to transmit configuration
information to the wireless device which configures the wireless
device to operate with the adapted flexible subframe allocation
scheme.
[0201] In still another alternative way to describe the embodiment
in FIG. 7b, the network node 120 may comprise a Central Processing
Unit (CPU) which may be a single unit or a plurality of units.
Furthermore, the network node 120 may comprise at least one
computer program product (CPP) 792 with a computer readable medium
793 in the form of a non-volatile memory, e.g. an EEPROM
(Electrically Erasable Programmable Read-Only Memory), a flash
memory or a disk drive. The CPP 792 may comprise a computer program
791 stored on the computer readable medium 793, which comprises
code means which when run on the CPU of the network node 120 causes
the network node 120 to perform the methods described earlier in
conjunction with FIGS. 6a-b. In other words, when said code means
are run on the CPU, they correspond to the processing module 750 in
FIG. 7b.
Embodiments of Methods and Apparatus Described with Reference to
FIGS. 3a, 3b, 4a and 4b
[0202] In FIG. 3a, an exemplifying, schematic flowchart of the
method in the wireless device 110 is shown. FIG. 3a describes the
actions performed by the wireless device 110 in FIG. 2 (see above
for the descriptions of the actions). The actions of the flowchart
may be performed in any suitable order.
[0203] With reference to FIG. 3b, a schematic block diagram of the
wireless device 110 is shown. The wireless device 110 is configured
to perform the methods in FIG. 2 and FIG. 3a. According to some
embodiments herein, the wireless device 110 may comprise a
processing module 810. In further embodiments, the processing
module 810 may comprise one or more of an obtaining module 820, a
receiving module 830, a determining module 840 and a sending module
850. The wireless device 110 may further comprise an Input/output
(I/O) unit 804 configured to send and/or receive the DL data, the
SI, configurations described herein, messages, values, indications
and the like as described herein. The I/O unit 804 may comprise the
receiving module 830, the sending module 850, a transmitter and/or
a receiver. Furthermore, the wireless device 110 may comprise a
memory 805 for storing software to be executed by, for example, the
processing module when the processing module is implemented as a
hardware module comprising at least one processor or the like.
[0204] FIG. 3b also illustrates software in the form of a computer
program 801, comprising computer readable code units which when
executed on the wireless device 110 causes the wireless device 110
to perform the method according to FIGS. 2 and/or 7. Finally, FIG.
3b illustrates a computer program product 802, comprising computer
readable medium 803 and the computer program 801 as described
directly above stored on the computer readable medium 803.
[0205] In FIG. 4a, an exemplifying, schematic flowchart of the
method in the first network node 120 is shown. FIG. 4a describes
the actions performed by the first network node 120 in FIG. 2 (see
above for the descriptions of the actions). The actions of the
flowchart may be performed in any suitable order.
[0206] With reference to FIG. 4b, a schematic block diagram of the
first network node 120 is shown. The first network node 120 is
configured to perform the methods in FIGS. 2 and 4a.
[0207] According to some embodiments herein, the first network node
120 may comprise a processing module 1010. In further embodiments,
the processing module 1010 may comprise one or more of a
configuring module 1020, a sending module 1030, a receiving module
1040.
[0208] The first network node 120 may further comprise an
Input/output (I/O) unit 1004 configured to send and/or receive the
DL data, the SI, configurations described herein, messages, values,
indications and the like as described herein. The I/O unit 1004 may
comprise the receiving module 1040, the sending module 1030, a
transmitter and/or a receiver.
[0209] Furthermore, the first network node 120 may comprise a
memory 1005 for storing software to be executed by, for example,
the processing module when the processing module is implemented as
a hardware module comprising at least one processor or the
like.
[0210] FIG. 4b also illustrates software in the form of a computer
program 1001, comprising computer readable code units which when
executed on the first network node 120 causes the first network
node 120 to perform the method according to FIGS. 2 and/or 9.
[0211] Finally, FIG. 4b illustrates a computer program product
1002, comprising computer readable medium 1003 and the computer
program 1001 as described directly above stored on the computer
readable medium 1003.
Listing of Non-Limiting Examples of the Method Performed by the
UE
[0212] 1. A method, in a UE served by a first network node
operating a first cell, for acquiring SI of a second cell operated
by a second network node, the method comprising: [0213] Creating
autonomous gaps for acquiring the SI of the second cell during a
time period (T0); [0214] Determining a minimum number of UL
feedback signals that the UE is required to transmit in response to
continuous transmission of DL data to the UE by the first network
node during the time period, e.g. T0; [0215] wherein the minimum
number of UL feedback signals to be transmitted is associated with
a dynamic or flexible subframe allocation scheme; and [0216]
wherein the at least one subframe number is change-able between at
least any two of the UL, DL and special subframes during the time
period, e.g. T0 according to the scheme; [0217] Transmitting the
determined minimum number of UL feedback signals in response to the
continuous transmission of DL data during the time period, e.g.
T0.
[0218] 2. The method according to example 1, wherein the second
cell is a neighbor cell of the first cell or the second cell is the
same as the first cell.
[0219] 3. The method according to any of the preceding examples,
wherein the SI comprises of at least one of MIB, SIB1 and CGI.
[0220] 4. The method according to any of the preceding examples,
wherein the UL feedback signal is ACK and NACK transmitted in
response to receiving DL data channel.
[0221] 5. The method according to any of the preceding examples,
wherein DL data channel is PDSCH.
[0222] 6. The method according to any of the preceding examples,
wherein the dynamic or flexible subframe allocation scheme further
comprises of any of: [0223] HD-FDD operation, wherein UL and DL
subframes do not overlap in time but they are transmitted on
different carrier frequencies, and the at least one subframe
changes between at least any two of UL, DL and unused subframes
during the time period, e.g. T0; [0224] Dynamic TDD wherein at
least one subframe changes between at least any two of UL subframe,
DL subframe and special subframe during the time period, e.g.
T0.
[0225] 7. The method according to any of the preceding examples,
wherein the dynamic TDD comprises operating by using at least two
different UL and DL TDD configuration during the time period, e.g.
T0.
[0226] 8. The method according to any of the preceding examples,
wherein receiving a request from the first network node to acquire
the SI of the second cell.
[0227] 9. The method according to any of the preceding examples,
wherein the UE configuration during at least part of T0 further
comprises of one or more of the following: [0228] UE is NOT
configured with a measurement gap; [0229] UE is NOT configured with
any DRX cycle or UE is not operating in DRX, [0230] UE is
configured to receive DL data from the first network node with a
pre-defined number of code word in one subframe and [0231] No MBSFN
subframe is configured in serving cell (or PCell)
[0232] 10. The method according to any of the preceding examples,
wherein acquiring the SI of the second cell during the time period,
e.g. T0 using the autonomous gap.
[0233] 11. The method according to any of the preceding examples,
wherein using the acquired SI of the second cell for at least one
of: [0234] Signaling the acquired SI to the first network node or
to another UE; [0235] Storing the acquired SI in the memory for use
at future time, and [0236] Comparing the CGI in the SI with the PCI
for verifying the identification of the second cell.
[0237] 12. The method according to any of the preceding examples,
wherein determining the said minimum number of UL feedback signals
that are required to be transmitted based on one of: [0238]
Received indication from the first network node; [0239] Pre-defined
information.
[0240] 13. The method according to example 11, wherein pre-defined
information comprises one of: [0241] Pre-defined number of UL
signals required to be transmitted; [0242] Pre-defined rule; and
[0243] Pre-defined expression or function
EXAMPLE IMPLEMENTATIONS
A. First Example
[0244] According to section 8.1.2.2.4 of TS 36.133 Rel-12, version
12.2.0, E-UTRAN TDD intra frequency measurements with autonomous
gaps, the UE has to be compliant to, or obey, a set of rules as
described in the following.
Identification of a New CGI of E-UTRA Cell with Autonomous Gaps
[0245] No explicit neighbour list is provided to the UE for
identifying a new CGI of E-UTRA cell. The UE shall identify and
report the CGI when requested by the network for the purpose
`reportCGI`. The UE may make autonomous gaps in downlink reception
and UL transmission for receiving MIB and SIB1 messages according
to clause 5.5.3.1 of TS 36.331. Note that a UE is not required to
use autonomous gap if si-RequestForHO is set to false. If
autonomous gaps are used for measurement with the purpose of
`reportCGI`, the UE shall be able to identify a new CGI of E-UTRA
cell within:
T.sub.identify.sub._.sub.CGI,intra=T.sub.basic.sub._.sub.identify.sub._.-
sub.CGI,intrams
where T.sub.basic.sub._.sub.identify.sub._.sub.CGI, intra=150 ms.
This is the time period used in the above equation where the
maximum allowed time for the UE to identify a new CGI of an E-UTRA
cell is defined, provided that the E-UTRA cell has been already
identified by the UE.
[0246] A cell shall be considered identifiable when the following
conditions are fulfilled: [0247] RSRP related side conditions are
fulfilled for a corresponding Band, [0248] SCH_RP and SCH Es/Iot
for a corresponding Band
[0249] The MIB of an E-UTRA cell whose CGI is identified shall be
considered decodable by the UE provided certain PBCH demodulation
requirements are met (e.g. under certain SNR level).
[0250] The requirement for identifying a new CGI of an E-UTRA cell
within T.sub.basic.sub._.sub.identify.sub._.sub.CGI, intra is
applicable when no DRX is used as well as when all the DRX cycles
specified in TS 36.331 are used.
[0251] Within the time, where T.sub.identify.sub._.sub.CGI, intra
ms, over which the UE identifies the new CGI of E-UTRA cell, the UE
shall be able to transmit at least the number of ACK/NACKs stated
in Table 2 (same as Table 2 in background section) provided that:
[0252] there is continuous DL data allocation, [0253] no DRX cycle
is used, [0254] no measurement gaps are configured, [0255] only one
code word is transmitted in each subframe
[0256] Table 2 (replica of Table 2 in background section):
Requirement on minimum number of ACK/NACKs to transmit during
T.sub.basic.sub._.sub.identify.sub._.sub.CGI, intra.
TABLE-US-00003 Minimum number of UL/DL transmitted configuration
ACK/NACKs 0 18 1 35 2 43 3 36 4 39 5 42 6 30
ECGI Reporting Delay
[0257] The ECGI reporting delay occurs due to the delay uncertainty
when inserting the ECGI measurement report to the TTI of the UL
DCCH. The delay uncertainty is twice the TTI of the UL DCCH. In
case DRX is used, the ECGI reporting may be delayed until the next
DRX cycle. If IDC autonomous denial is configured, an additional
delay can be expected.
Requirement on UE for this First Example According to Embodiments
of Invention
[0258] However according to embodiments of the invention, if at
least one flexible subframe is used in the PCell of the UE within
the time, T.sub.identify.sub._.sub.CGI, intra ms, over which the UE
identifies the new CGI of E-UTRA cell, then the UE shall be able to
transmit at least 18 ACK/NACKs provided that: [0259] there is
continuous DL data allocation, [0260] no DRX cycle is used, [0261]
no measurement gaps are configured, [0262] only one code word is
transmitted in each subframe and [0263] no MBSFN subframe is
configured in the PCell.
B. Second Example
[0264] According to section 8.1.2.3.6 of TS 36.133 Rel-12, version
12.2.0, E-UTRAN TDD-FDD inter frequency measurements using
autonomous gaps, the UE has to be compliant to, or obey, a set of
rules as described in the following. The requirements in this
clause shall apply to a UE supporting FDD and TDD.
Identification of a New CGI of E-UTRA FDD Cell with Autonomous
Gaps
[0265] No explicit neighbour list is provided to the UE for
identifying a new CGI of E-UTRA cell. The UE shall identify and
report the CGI when requested by the network for the purpose of
`reportCGI`. The UE may make autonomous gaps in both downlink
reception and UL transmission for receiving MIB and SIB1 message
according to clause 5.5.3.1 of TS 36.331. Note that a UE is not
required to use autonomous gap if si-RequestForHO is set to false.
If autonomous gaps are used for measurement with the purpose of
`reportCGI`, regardless of whether DRX is used or not, the UE shall
be able to identify a new CGI of E-UTRA cell within:
T.sub.identify.sub._.sub.CGI,inter=T.sub.basic.sub._.sub.identify.sub._.-
sub.CGI,interms
Where
[0266] T.sub.basic.sub._.sub.identify.sub._.sub.CGI, inter=150 ms.
This is the time period used in the above equation where the
maximum allowed time for the UE to identify a new CGI of E-UTRA
cell is defined, provided that the E-UTRA cell has been already
identified by the UE.
[0267] A cell shall be considered identifiable when the following
conditions are fulfilled: [0268] RSRP related side conditions are
fulfilled for a corresponding Band, [0269] SCH_RPl.sub.dBm and SCH
Es/Iot for a corresponding Band.
[0270] The MIB of an E-UTRA cell whose CGI is identified shall be
considered decodable by the UE provided certain PBCH demodulation
requirements are met (e.g. under certain SNR level).
[0271] The requirement for identifying a new CGI of an E-UTRA cell
within T.sub.basic.sub._.sub.identify.sub._.sub.CGI,inter is
applicable when no DRX is used as well as when all the DRX cycles
specified in TS 36.331 are used.
[0272] Given that continuous DL data allocation and no DRX is used,
no measurement gaps are configured, and TDD configuration as
specified in TS 36.331 is used, the UE shall have more than 30
ACK/NACK transmitted during the identification of a new CGI of
E-UTRA cell.
ECGI Reporting Delay
[0273] The ECGI reporting delay occurs due to the delay uncertainty
when inserting the ECGI measurement report to the TTI of the UL
DCCH. The delay uncertainty is twice the TTI of the UL DCCH. In
case DRX is used, the ECGI reporting may be delayed until the next
DRX cycle. If IDC autonomous denial is configured, an additional
delay can be expected.
Requirement on UE for this Second Example According to Embodiments
of Invention
[0274] However according to embodiments of the invention, if at
least one flexible subframe is used in the PCell of the UE within
the time, T.sub.identify.sub._.sub.CGI, inter ms, over which the UE
identifies the new CGI of E-UTRA cell, then the UE shall be able to
transmit at least 18 ACK/NACKs provided that: [0275] there is
continuous DL data allocation, [0276] no DRX cycle is used, [0277]
no measurement gaps are configured, [0278] only one code word is
transmitted in each subframe and [0279] no MBSFN subframe is
configured in the PCell.
C. Third Example
[0280] According to section 8.1.2.3.7 of TS 36.133 Rel-12, version
12.2.0, E-UTRAN TDD-TDD inter frequency measurements with
autonomous gaps, the UE has to be compliant to, or obey, a set of
rules as described in the following.
Identification of a New CGI of E-UTRA TDD Cell with Autonomous
Gaps
[0281] No explicit neighbour list is provided to the UE for
identifying a new CGI of E-UTRA cell. The UE shall identify and
report the CGI when requested by the network for the purpose of
`reportCGI`. The UE may make autonomous gaps in both downlink
reception and UL transmission for receiving MIB and SIB1 message
according to clause 5.5.3.1 of TS 36.331. Note that a UE is not
required to use autonomous gap if si-RequestForHO is set to false.
If autonomous gaps are used for measurement with the purpose of
`reportCGI`, regardless of whether DRX is used or not, the UE shall
be able to identify a new CGI of E-UTRA cell within:
T.sub.identify.sub._.sub.CGI,inter=T.sub.basic.sub._.sub.identify.sub._.-
sub.CGI,interms
Where
[0282] T.sub.basic.sub._.sub.identify.sub._.sub.CGI, inter=150 ms.
This is the time period used in the above equation where the
maximum allowed time for the UE to identify a new CGI of E-UTRA
cell is defined, provided that the E-UTRA cell has been already
identified by the UE.
[0283] A cell shall be considered identifiable when the following
conditions are fulfilled: [0284] RSRP related side conditions are
fulfilled for a corresponding Band, [0285] SCH_RP and SCH Es/Iot
for a corresponding Band.
[0286] The MIB of an E-UTRA cell whose CGI is identified shall be
considered decodable by the UE provided certain PBCH demodulation
requirements are met (e.g. under certain SNR level).
[0287] The requirement for identifying a new CGI of an E-UTRA cell
within T.sub.basic.sub._.sub.identify.sub._.sub.CGI,Inter is
applicable when no DRX is used as well as when all the DRX cycles
specified in TS 36.331 are used.
[0288] Given that continuous DL data allocation and no DRX is used,
no measurement gaps are configured, and TDD configuration as
specified in TS 36.331 is used, the UE shall have more than 30
ACK/NACKs transmitted during the identification of a new CGI of
E-UTRA cell.
ECGI Reporting Delay
[0289] The ECGI reporting delay occurs due to the delay uncertainty
when inserting the ECGI measurement report to the TTI of the UL
DCCH. The delay uncertainty is twice the TTI of the UL DCCH. In
case DRX is used, the ECGI reporting may be delayed until the next
DRX cycle. If IDC autonomous denial is configured, an additional
delay can be expected.
Requirement on UE for this Third Example According to Embodiments
of Invention
[0290] However according to embodiments of the invention, if at
least one flexible subframe is used in the PCell of the UE within
the time, T.sub.basic.sub._.sub.identify.sub._.sub.CGI,Inter ms,
over which the UE identifies the new CGI of E-UTRA cell, then the
UE shall be able to transmit at least 18 ACK/NACKs provided that:
[0291] there is continuous DL data allocation, [0292] no DRX cycle
is used, [0293] no measurement gaps are configured, [0294] only one
code word is transmitted in each subframe and [0295] no MBSFN
subframe is configured in the PCell.
Terminology
[0296] As used herein, the term "processing module" may refer to a
processing circuit, a processing unit, a processor, an Application
Specific integrated Circuit (ASIC), a Field-Programmable Gate Array
(FPGA) or the like. As an example, a processor, an ASIC, an FPGA or
the like may comprise one or more processor kernels. In some
examples, the processing module may be embodied by a software
module or hardware module. Any such module may be a determining
means, estimating means, capturing means, associating means,
comparing means, identification means, selecting means, receiving
means, transmitting means or the like as disclosed herein. As an
example, the expression "means" may be a module, such as a
determining module, selecting module, etc.
[0297] As used herein, the expression "configured to" may mean that
a processing circuit is configured to, or adapted to, by means of
software configuration and/or hardware configuration, perform one
or more of the actions described herein.
[0298] As used herein, the term "memory" may refer to a hard disk,
a magnetic storage medium, a portable computer diskette or disc,
flash memory, random access memory (RAM) or the like. Furthermore,
the term "memory" may refer to an internal register memory of a
processor or the like.
[0299] As used herein, the term "computer readable medium" may be a
Universal Serial Bus (USB) memory, a DVD-disc, a Blu-ray disc, a
software module that is received as a stream of data, a Flash
memory, a hard drive, a memory card, such as a MemoryStick, a
Multimedia Card (MMC), etc.
[0300] As used herein, the term "computer readable code units" may
be text of a computer program, parts of or an entire binary file
representing a computer program in a compiled format or anything
there between.
[0301] As used herein, the terms "number", "value" may be any kind
of digit, such as binary, real, imaginary or rational number or the
like. Moreover, "number", "value" may be one or more characters,
such as a letter or a string of letters. "number", "value" may also
be represented by a bit string.
[0302] As used herein, the expression "in some embodiments" has
been used to indicate that the features of the embodiment described
may be combined with any other embodiment disclosed herein.
[0303] Even though embodiments of the various aspects have been
described, many different alterations, modifications and the like
thereof will become apparent for those skilled in the art.
[0304] The described embodiments are therefore not intended to
limit the scope of the present disclosure.
ABBREVIATIONS
[0305] BCH Broadcast channel [0306] BS Base Station [0307] CA
Carrier Aggregation [0308] CGI Cell global identifier [0309] CPICH
Common Pilot Channel [0310] DL Downlink [0311] DRX Discontinuous
Reception [0312] EARFCN Evolved absolute radio frequency channel
number [0313] ECGI E-UTRAN CGI [0314] E-CID Enhanced cell ID [0315]
E-SMLC Evolved SMLC [0316] E-UTRAN Evolved Universal Terrestrial
Radio Access Network [0317] GSM Global System for Mobile
Communications [0318] HARQ Hybrid Automatic Repeat Request [0319]
L1 Layer 1 [0320] L2 Layer 2 [0321] LMU Location measurement unit
[0322] LPP LTE positioning protocol [0323] LPPa LTE positioning
protocol annex [0324] LTE Long Term Evolution [0325] MAC Medium
Access Control [0326] MBSFN Multimedia Broadcast multicast service
Single Frequency Network [0327] MIB Master Information Block [0328]
MME Mobility management entity [0329] OFDM Orthogonal Frequency
Division Modulation [0330] OFDMA Orthogonal Frequency Division
Multiple Access [0331] O&M Operational and Maintenance [0332]
OTDOA Observed time difference of arrival [0333] PBCH Physical
Broadcast Channel [0334] PCI Physical cell identifier [0335] PDSCH
Physical Downlink Shared Channel [0336] RAT Radio Access Technology
[0337] RN Relay node [0338] RNC Radio Network Controller [0339] RRC
Radio Resource Control [0340] RSCP Received Signal Code Power
[0341] RSRQ Reference signal received quality [0342] RSRP Reference
signal received power [0343] RSTD Reference signal time difference
[0344] SMLC Serving Mobile Location Center [0345] SON Self
Organizing Network [0346] RSSI Received signal strength indicator
[0347] SIB System information block [0348] SI System information
[0349] UE User Equipment [0350] UL Uplink [0351] UTDOA UL time
difference of arrival [0352] X2 an interface for BS-to-BS
communication in LTE
* * * * *