U.S. patent application number 15/590830 was filed with the patent office on 2017-11-16 for systems and methods for physical uplink shared channel (pusch) format signaling and contention access.
The applicant listed for this patent is Sharp Laboratories of America, Inc.. Invention is credited to Toshizo Nogami, Zhanping Yin.
Application Number | 20170332395 15/590830 |
Document ID | / |
Family ID | 58765931 |
Filed Date | 2017-11-16 |
United States Patent
Application |
20170332395 |
Kind Code |
A1 |
Yin; Zhanping ; et
al. |
November 16, 2017 |
SYSTEMS AND METHODS FOR PHYSICAL UPLINK SHARED CHANNEL (PUSCH)
FORMAT SIGNALING AND CONTENTION ACCESS
Abstract
A user equipment (UE) for transmitting signals in a
Licensed-Assisted Access (LAA) serving cell is described. The UE
includes a processor and memory in electronic communication with
the processor. The UE receives an uplink (UL) grant for one or more
UL LAA subframes from one or more downlink control information
(DCI). The UE also determines a UL LAA physical uplink shared
channel (PUSCH) format or structure for a UL LAA subframe. The UE
further determines whether listen before talk (LBT) is needed for a
scheduled LAA PUSCH. If needed, the UE determines a UL contention
access region based on the UL grant for a UL LAA subframe. The UE
also determines a UL contention access method in the contention
access region. The UE further performs UL contention access in the
UL contention access region. The UE additionally transmits the LAA
PUSCH if channel access succeeds.
Inventors: |
Yin; Zhanping; (Vancouver,
WA) ; Nogami; Toshizo; (Vancouver, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Sharp Laboratories of America, Inc. |
Camas |
WA |
US |
|
|
Family ID: |
58765931 |
Appl. No.: |
15/590830 |
Filed: |
May 9, 2017 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62334964 |
May 11, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 16/14 20130101;
H04W 72/1263 20130101; H04W 84/042 20130101; H04W 74/0816 20130101;
H04W 72/1294 20130101; H04W 74/006 20130101; H04W 72/1268
20130101 |
International
Class: |
H04W 72/12 20090101
H04W072/12; H04W 72/12 20090101 H04W072/12; H04W 16/14 20090101
H04W016/14; H04W 72/12 20090101 H04W072/12; H04W 84/04 20090101
H04W084/04; H04W 74/08 20090101 H04W074/08 |
Claims
1. A user equipment (UE) for transmitting signals in a
Licensed-Assisted Access (LAA) serving cell, comprising: a
processor; and memory in electronic communication with the
processor, wherein instructions stored in the memory are executable
to: receive an uplink (UL) grant for one or more UL LAA subframes
from one or more downlink control information (DCI); determine a UL
LAA physical uplink shared channel (PUSCH) format or structure for
a UL LAA subframe; and determine whether listen before talk (LBT)
is needed for a scheduled LAA PUSCH; and if needed determine a UL
contention access region based on the UL grant for a UL LAA
subframe; determine a UL contention access method in the contention
access region; perform UL contention access in the UL contention
access region; and transmit the LAA PUSCH if channel access
succeeds.
2. The UE of claim 1, wherein the UL grant DCI indicates the LAA
PUSCH format of the scheduled subframe and information about the
availability of the last symbol of the previous subframe.
3. The UE of claim 1, wherein the UL LAA PUSCH format or structure
for a UL LAA subframe may start from symbol 0 or 1 and may end at
symbol 12 or symbol 13.
4. The UE of claim 1, wherein the UL LAA PUSCH starts at symbol 0,
and the last symbol of a previous subframe is not blank, and when a
previous LAA subframe transmission is successful, the UE transmits
the scheduled LAA PUSCH without LBT.
5. The UE of claim 1, wherein the contention access region is
determined based on an indicated LAA PUSCH structure.
6. The UE of claim 1, wherein the contention access region is
determined based on an indicated LAA PUSCH structure and whether
the last symbol of a previous subframe is blank.
7. A method for transmitting signals in a Licensed-Assisted Access
(LAA) serving cell, comprising: receiving an uplink (UL) grant for
one or more UL LAA subframes from one or more downlink control
information (DCI); determining a UL LAA physical uplink shared
channel (PUSCH) format or structure for a UL LAA subframe; and
determining whether listen before talk (LBT) is needed for a
scheduled LAA PUSCH; and if needed determining a UL contention
access region based on the UL grant for a UL LAA subframe;
determining a UL contention access method in the contention access
region; performing UL contention access in the UL contention access
region; and transmitting the LAA PUSCH if channel access
succeeds.
8. The method of claim 7, wherein the UL grant DCI indicates the
LAA PUSCH format of the scheduled subframe and information about
the availability of the last symbol of the previous subframe.
9. The method of claim 7, wherein the UL LAA PUSCH format or
structure for a UL LAA subframe may start from symbol 0 or 1 and
may end at symbol 12 or symbol 13.
10. The method of claim 7, wherein the UL LAA PUSCH starts at
symbol 0, and the last symbol of a previous subframe is not blank,
and when a previous LAA subframe transmission is successful, the UE
transmits the scheduled LAA PUSCH without LBT.
11. The method of claim 7, wherein the contention access region is
determined based on an indicated LAA PUSCH structure.
12. The method of claim 7, wherein the contention access region is
determined based on an indicated LAA PUSCH structure and whether
the last symbol of a previous subframe is blank.
Description
RELATED APPLICATIONS
[0001] This application is related to and claims priority from U.S.
Provisional Patent Application No. 62/334,964, entitled "SYSTEMS
AND METHODS FOR PHYSICAL UPLINK SHARED CHANNEL (PUSCH) FORMAT
SIGNALING AND CONTENTION ACCESS," filed on May 11, 2016, which is
hereby incorporated by reference herein, in its entirety.
TECHNICAL FIELD
[0002] The present disclosure relates generally to communication
systems. More specifically, the present disclosure relates to user
equipments (UEs), base stations and methods.
BACKGROUND
[0003] Wireless communication devices have become smaller and more
powerful in order to meet consumer needs and to improve portability
and convenience. Consumers have become dependent upon wireless
communication devices and have come to expect reliable service,
expanded areas of coverage and increased functionality. A wireless
communication system may provide communication for a number of
wireless communication devices, each of which may be serviced by a
base station. A base station may be a device that communicates with
wireless communication devices.
[0004] As wireless communication devices have advanced,
improvements in communication capacity, speed, flexibility and/or
efficiency have been sought. However, improving communication
capacity, speed, flexibility and/or efficiency may present certain
problems.
[0005] For example, wireless communication devices may communicate
with one or more devices using a communication structure. However,
the communication structure used may only offer limited flexibility
and/or efficiency. As illustrated by this discussion, systems and
methods that improve communication flexibility and/or efficiency
may be beneficial.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a block diagram illustrating one implementation of
one or more evolved NodeBs (eNBs) and one or more user equipments
(UEs) in which systems and methods for physical uplink shared
channel (PUSCH) format signaling and contention access may be
implemented;
[0007] FIG. 2 is a flow diagram illustrating a method for PUSCH
format signaling and contention access by a UE;
[0008] FIG. 3 illustrates the hidden node problem for uplink (UL)
transmission without listen before talk (LBT);
[0009] FIG. 4 is a diagram illustrating a category 2 UL
Licensed-Assisted Access (LAA) transmission;
[0010] FIG. 5 illustrates an example a single clear channel
assessment (CCA) sensing of at least 25 microseconds (.mu.s) at the
beginning of a CCA gap;
[0011] FIG. 6 is a diagram illustrating implementations of an LAA
PUSCH with required listen before talk (LBT) channel access and no
blank symbol;
[0012] FIG. 7 is a diagram illustrating determining whether LBT is
needed by the status of a previous UL LAA subframe
transmission;
[0013] FIG. 8 is a diagram illustrating options for a CCA gap and
LBT in the case of a failed transmission in a previous
subframe;
[0014] FIG. 9 is a flow diagram illustrating a method for LAA PUSCH
format signaling and performing contention access;
[0015] FIG. 10 is a flow diagram illustrating a method for
performing a case 1 LBT;
[0016] FIG. 11 is a flow diagram illustrating a method for
performing a case 3 LBT;
[0017] FIG. 12 illustrates various components that may be utilized
in a UE;
[0018] FIG. 13 illustrates various components that may be utilized
in an eNB;
[0019] FIG. 14 is a block diagram illustrating one implementation
of a UE in which systems and methods for PUSCH format signaling and
contention access may be implemented; and
[0020] FIG. 15 is a block diagram illustrating one implementation
of an eNB in which systems and methods for PUSCH format signaling
and contention access may be implemented.
DETAILED DESCRIPTION
[0021] A user equipment (UE) for transmitting signals in a
Licensed-Assisted Access (LAA) serving cell is described. The UE
includes a processor and memory in electronic communication with
the processor. The UE receives an uplink (UL) grant for one or more
UL LAA subframes from one or more downlink control information
(DCI). The UE also determines a UL LAA physical uplink shared
channel (PUSCH) format or structure for a UL LAA subframe. The UE
further determines whether listen before talk (LBT) is needed for a
scheduled LAA PUSCH. If needed, the UE determines a UL contention
access region based on the UL grant for a UL LAA subframe. The UE
also determines a UL contention access method in the contention
access region. The UE further performs UL contention access in the
UL contention access region. The UE additionally transmits the LAA
PUSCH if channel access succeeds.
[0022] The UL grant DCI may indicate the LAA PUSCH format of the
scheduled subframe and information about the availability of the
last symbol of the previous subframe.
[0023] The UL LAA PUSCH format or structure for a UL LAA subframe
may start from symbol 0 or 1 and may end at symbol 12 or symbol
13.
[0024] The UL LAA PUSCH may start at symbol 0 and the last symbol
of the previous subframe may not be blank. When the previous LAA
subframe transmission is successful, the UE may transmit the
scheduled LAA PUSCH without LBT.
[0025] The contention access region may be determined based on the
indicated LAA PUSCH structure. The contention access region may be
determined based on the indicated LAA PUSCH structure and whether
the last symbol of the previous subframe is blank.
[0026] A method for transmitting signals in an LAA serving cell is
also described. The method includes receiving a UL grant for one or
more UL LAA subframes from one or more DCI. The method also
includes determining a UL LAA PUSCH format or structure for a UL
LAA subframe. The method further includes determining whether LBT
is needed for a scheduled LAA PUSCH. If needed, the method
additionally includes determining a UL contention access region
based on the UL grant for a UL LAA subframe. The method also
includes determining a UL contention access method in the
contention access region. The method further includes performing UL
contention access in the UL contention access region. The method
additionally includes transmitting the LAA PUSCH if channel access
succeeds.
[0027] The 3rd Generation Partnership Project, also referred to as
"3GPP," is a collaboration agreement that aims to define globally
applicable technical specifications and technical reports for third
and fourth generation wireless communication systems. The 3GPP may
define specifications for next generation mobile networks, systems
and devices.
[0028] 3GPP Long Term Evolution (LTE) is the name given to a
project to improve the Universal Mobile Telecommunications System
(UMTS) mobile phone or device standard to cope with future
requirements. In one aspect, UMTS has been modified to provide
support and specification for the Evolved Universal Terrestrial
Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio
Access Network (E-UTRAN).
[0029] At least some aspects of the systems and methods disclosed
herein may be described in relation to the 3GPP LTE, LTE-Advanced
(LTE-A) and other standards (e.g., 3GPP Releases 8, 9, 10, 11
and/or 12). However, the scope of the present disclosure should not
be limited in this regard. At least some aspects of the systems and
methods disclosed herein may be utilized in other types of wireless
communication systems.
[0030] A wireless communication device may be an electronic device
used to communicate voice and/or data to a base station, which in
turn may communicate with a network of devices (e.g., public
switched telephone network (PSTN), the Internet, etc.). In
describing systems and methods herein, a wireless communication
device may alternatively be referred to as a mobile station, a UE,
an access terminal, a subscriber station, a mobile terminal, a
remote station, a user terminal, a terminal, a subscriber unit, a
mobile device, etc. Examples of wireless communication devices
include cellular phones, smart phones, personal digital assistants
(PDAs), laptop computers, netbooks, e-readers, wireless modems,
etc. In 3GPP specifications, a wireless communication device is
typically referred to as a UE. However, as the scope of the present
disclosure should not be limited to the 3GPP standards, the terms
"UE" and "wireless communication device" may be used
interchangeably herein to mean the more general term "wireless
communication device." A UE may also be more generally referred to
as a terminal device.
[0031] In 3GPP specifications, a base station is typically referred
to as a Node B, an evolved Node B (eNB), a home enhanced or evolved
Node B (HeNB) or some other similar terminology. As the scope of
the disclosure should not be limited to 3GPP standards, the terms
"base station," "Node B," "eNB," and "HeNB" may be used
interchangeably herein to mean the more general term "base
station." Furthermore, the term "base station" may be used to
denote an access point. An access point may be an electronic device
that provides access to a network (e.g., Local Area Network (LAN),
the Internet, etc.) for wireless communication devices. The term
"communication device" may be used to denote both a wireless
communication device and/or a base station. An eNB may also be more
generally referred to as a base station device.
[0032] It should be noted that as used herein, a "cell" may refer
to any set of communication channels over which the protocols for
communication between a UE and eNB that may be specified by
standardization or governed by regulatory bodies to be used for
International Mobile Telecommunications-Advanced (IMT-Advanced) or
its extensions and all of it or a subset of it may be adopted by
3GPP as licensed bands (e.g., frequency bands) to be used for
communication between an eNB and a UE. "Configured cells" are those
cells of which the UE is aware and is allowed by an eNB to transmit
or receive information. "Configured cell(s)" may be serving
cell(s). The UE may receive system information and perform the
required measurements on all configured cells. "Activated cells"
are those configured cells on which the UE is transmitting and
receiving. That is, activated cells are those cells for which the
UE monitors the physical downlink control channel (PDCCH) and in
the case of a downlink transmission, those cells for which the UE
decodes a physical downlink shared channel (PDSCH). "Deactivated
cells" are those configured cells that the UE is not monitoring the
transmission PDCCH. It should be noted that a "cell" may be
described in terms of differing dimensions. For example, a "cell"
may have temporal, spatial (e.g., geographical) and frequency
characteristics.
[0033] The systems and methods disclosed may involve carrier
aggregation (CA). Carrier aggregation refers to the concurrent
utilization of more than one carrier. In carrier aggregation, more
than one cell may be aggregated to a UE. In one example, carrier
aggregation may be used to increase the effective bandwidth
available to a UE. The same time division duplex (TDD)
uplink-downlink (UL/DL) configuration has to be used for TDD CA in
Release-10, and for intra-band CA in Release-11. In Release-11,
inter-band TDD CA with different TDD UL/DL configurations is
supported. The inter-band TDD CA with different TDD UL/DL
configurations may provide the flexibility of a TDD network in CA
deployment. Furthermore, enhanced interference management with
traffic adaptation (eIMTA) (also referred to as dynamic UL/DL
reconfiguration) may allow flexible TDD UL/DL reconfiguration based
on the network traffic load.
[0034] It should be noted that the term "concurrent" and variations
thereof as used herein may denote that two or more events may
overlap each other in time and/or may occur near in time to each
other. Additionally, "concurrent" and variations thereof may or may
not mean that two or more events occur at precisely the same
time.
[0035] An LTE UL transmission may be scheduled by an eNB with an
uplink grant. A UL grant may be a DCI format in a physical downlink
control channel (PDCCH), an enhanced PDCCH (EPDCCH), or Physical
Hybrid ARQ Indicator Channel (PHICH) feedback. The time between a
UL grant and the scheduled UL transmission is at least 4
milliseconds (ms). The eNB may schedule multiple LAA subframe
transmissions for a single LAA UE. The eNB may schedule
simultaneous UL transmissions from multiple UEs in a single
subframe.
[0036] For enhanced LAA uplink transmissions, the LAA PUSCH format
can be indicated by dynamic signaling. The channel access methods
(e.g., the LBT method), may be configured jointly with or
independently from the PUSCH formats. However, there are some
inherent relationship between the LBT method and PUSCH format. In
some cases, the LBT method or PUSCH format cannot be performed as
indicated; some special handlings may be needed.
[0037] This disclosure describes use cases of different LAA PUSCH
formats and potential LBT methods that can be applied at each LAA
PUSCH format. Furthermore, the mechanisms to apply the appropriate
LBT and/or PUSCH structure under different conditions are described
herein.
[0038] Some methods have been proposed for LAA uplink transmission
for 3GPP. The candidates include single clear channel assessment
(CCA) sensing (e.g., 25 microsecond (.mu.s) initial CCA (ICCA) size
sensing) before transmission; random backoff within a contention
window size; random backoff with counter indicated by the eNB; and
no LBT if the temporal gap between a DL and UL transmission is very
small (e.g., less than 16 or 25 .mu.s).
[0039] The LBT method may be indicated for a UL LAA transmission.
For eLAA uplink LAA transmissions, different LBT methods may be
signaled for different LAA subframes. In a multiple subframe
scheduling, the same LBT method may be indicated for all subframes,
or a different LBT method can be indicated for each subframe in a
multiple subframe scheduling. Furthermore, the LBT method for each
subframe may be determined implicitly by the indicated LAA PUSCH
format.
[0040] However, to perform LBT, the LAA UE may need to know the
PUSCH format of the scheduled subframe as well as the LAA PUSCH
format of the previous subframe. For multiple subframe scheduling,
the indicated PUSCH format may not be usable if the previous
subframe LBT fails. Thus, some error handling and false back mode
operation may be performed.
[0041] The systems and methods described herein provide for the
following. The LAA PUSCH format of the current subframe and
previous subframe may be indicated in the DCI format of the UL
grant. The LBT method may be indicated by dynamic signaling, and
the LBT parameters may be explicitly signaled or implicitly
determined based on the CCA gap allocation. The LBT method may be
determined based on the format and location of a scheduled LAA
PUSCH. The LBT parameters may be modified in the case of a failed
LBT process in earlier subframes.
[0042] Various examples of the systems and methods disclosed herein
are now described with reference to the Figures, where like
reference numbers may indicate functionally similar elements. The
systems and methods as generally described and illustrated in the
Figures herein could be arranged and designed in a wide variety of
different implementations. Thus, the following more detailed
description of several implementations, as represented in the
Figures, is not intended to limit scope, as claimed, but is merely
representative of the systems and methods.
[0043] FIG. 1 is a block diagram illustrating one implementation of
one or more eNBs 160 and one or more UEs 102 in which systems and
methods for contention access may be implemented. The one or more
UEs 102 communicate with one or more eNBs 160 using one or more
antennas 122a-n. For example, a UE 102 transmits electromagnetic
signals to the eNB 160 and receives electromagnetic signals from
the eNB 160 using the one or more antennas 122a-n. The eNB 160
communicates with the UE 102 using one or more antennas 180a-n.
[0044] The UE 102 and the eNB 160 may use one or more channels 119,
121 to communicate with each other. For example, a UE 102 may
transmit information or data to the eNB 160 using one or more
uplink channels 121. Examples of uplink channels 121 include a
PUCCH and a PUSCH, etc. The one or more eNBs 160 may also transmit
information or data to the one or more UEs 102 using one or more
downlink channels 119, for instance. Examples of downlink channels
119 include a PDCCH, a PDSCH, etc. Other kinds of channels may be
used.
[0045] Each of the one or more UEs 102 may include one or more
transceivers 118, one or more demodulators 114, one or more
decoders 108, one or more encoders 150, one or more modulators 154,
a data buffer 104 and a UE operations module 124. For example, one
or more reception and/or transmission paths may be implemented in
the UE 102. For convenience, only a single transceiver 118, decoder
108, demodulator 114, encoder 150 and modulator 154 are illustrated
in the UE 102, though multiple parallel elements (e.g.,
transceivers 118, decoders 108, demodulators 114, encoders 150 and
modulators 154) may be implemented.
[0046] The transceiver 118 may include one or more receivers 120
and one or more transmitters 158. The one or more receivers 120 may
receive signals from the eNB 160 using one or more antennas 122a-n.
For example, the receiver 120 may receive and downconvert signals
to produce one or more received signals 116. The one or more
received signals 116 may be provided to a demodulator 114. The one
or more transmitters 158 may transmit signals to the eNB 160 using
one or more antennas 122a-n. For example, the one or more
transmitters 158 may upconvert and transmit one or more modulated
signals 156.
[0047] The demodulator 114 may demodulate the one or more received
signals 116 to produce one or more demodulated signals 112. The one
or more demodulated signals 112 may be provided to the decoder 108.
The UE 102 may use the decoder 108 to decode signals. The decoder
108 may produce decoded signals 110, which may include a UE-decoded
signal 106 (also referred to as a first UE-decoded signal 106). For
example, the first UE-decoded signal 106 may comprise received
payload data, which may be stored in a data buffer 104. Another
signal included in the decoded signals 110 (also referred to as a
second UE-decoded signal 110) may comprise overhead data and/or
control data. For example, the second UE-decoded signal 110 may
provide data that may be used by the UE operations module 124 to
perform one or more operations.
[0048] As used herein, the term "module" may mean that a particular
element or component may be implemented in hardware, software or a
combination of hardware and software. However, it should be noted
that any element denoted as a "module" herein may alternatively be
implemented in hardware. For example, the UE operations module 124
may be implemented in hardware, software or a combination of
both.
[0049] In general, the UE operations module 124 may enable the UE
102 to communicate with the one or more eNBs 160. The UE operations
module 124 may include one or more of a UL LAA PUSCH format
signaling and contention access module 126.
[0050] An enhanced licensed assisted access (eLAA) may be used for
uplink LAA transmission. eLAA may support multiple LAA subframe
scheduling. eLAA may have DCI format(s) to schedule PUSCH
transmission in k<=N subframes with single TB per subframe or
two TBs per subframe. The value(s) of N may be either
semi-statically configured or hard-coded.
[0051] DCI format(s) may have the following scheduling information
types. Type A may be common to all the scheduled subframes
(appearing only once in a DCI). Type A may include a carrier
indicator, resource assignment, cyclic shift for DM RS and OCC
index. Type B may include subframe-specific information (appearing
N times for N subframes scheduling).
[0052] For a LAA PUSCH format, the start and ending symbol may be
dynamically signaled. One symbol in a subframe containing PUSCH may
be blanked.
[0053] Dynamic signaling may indicate whether PUSCH in a UL
subframe is transmitted from start of DFT-S-OFDM symbol 0 or the
start of DFT-S-OFDM symbol 1. Dynamic signaling may indicate
whether PUSCH in a UL subframe is transmitted up to OFDM symbol 13
or OFDM symbol 12. Any combination of the above options can be
enabled by the dynamic signaling.
[0054] For channel access listen before talk (LBT) method, a single
25 .mu.s LBT within a maximum channel occupancy time (MCOT) may be
used as follows. If the sum total duration of DL and UL
transmissions (and UL LBT) is less than the obtained channel
occupancy duration, it is sufficient for the UE(s) 102 to perform a
single 25 .mu.s LBT to access the channel and perform UL
transmission.
[0055] Licensed-Assisted Access (LAA) supports LTE in unlicensed
spectrum. In a LAA network, the LAA subframe transmission occurs in
an opportunistic manner. Thus, listen before talk (LBT) with clear
channel assessment (CCA) is required before a LAA transmission. The
DL-only LAA was specified in LTE release-13.
[0056] An LTE UL transmission may be scheduled by an eNB 160 with
an uplink grant. A UL grant may be a DCI format in a PDCCH, EPDCCH,
or PHICH feedback. The time between a UL grant and the scheduled UL
transmission may be at least 4 ms. The eNB 160 may schedule
simultaneous UL transmissions from multiple UEs 102 in a single
subframe. For a scheduled UL transmission, the eNB 160 should make
sure there is no conflict between a DL and a UL on the same LAA
cell.
[0057] The LAA PUSCH subframe may have one or two blank symbols.
The blanked symbol space may be used for channel access. This space
may be called a contention access region or a CCA gap. For a LAA DL
transmission, the contention access or LBT may be performed at any
subframe and symbol location. On the other hand, the UL LAA is a
transmission scheduled by UL grant with a given timing. With UL
LAA, the LBT and contention access may only be performed in a
contention access region.
[0058] There are several approaches that may be implemented for UL
LBT. The pros and cons of these approaches are described below. In
a first approach, no LBT is performed if the temporal gap between a
DL and UL is very small. In this approach, a UL transmission may
happen without LBT if the gap between a DL and a UL is very small.
However, this approach has many restrictions. First, the LAA DL
transmission cannot avoid the hidden terminal issue, as described
in connection with FIG. 3.
[0059] In a second restriction, the start time of the UL LAA should
be known in advance or may be fixed. The ending time of a DL
transmission should be known in advance. Furthermore, this approach
only works for the first UL transmission after a DL LAA
transmission, and cannot be used for other LAA UL transmissions.
Additionally, the LAA DL burst should be last at least 4 ms in
order to keep the association timing between the DL scheduling DCI
and UL transmission. It is very difficult support variable length
LAA transmissions and consecutive UL LAA transmissions. Therefore,
although it is feasible in some cases for a LAA UL transmission
without LBT when the gap is very small, this approach brings many
restrictions and may be hard to justify.
[0060] However, in the case where there is no other present
unlicensed network (e.g. WiFi or LAA cells from other operators),
this approach may be applicable. Especially, if LAA patterns
include LAA DL and LAA UL subframes are defined, this approach can
be used.
[0061] In a second approach, a category 2 LBT may be performed
before a scheduled transmission. Category 2 LBT only requires a
single CCA sensing before transmission. This is also called frame
based equipment (FBE) contention access. Category 2 LBT may make
sense because a UL transmission is scheduled, and the UL
transmission should be dropped if it cannot get the channel at
scheduled time. Furthermore, this approach allows simultaneous UL
transmission from multiple UEs 102 since they all sense the same
CCA interval before transmission. An example of a category 2 UL LAA
transmission is described in connection with FIG. 4.
[0062] To avoid potential interruption of WiFi transmission, the
CCA sensing interval should have a length of a minimum defer
duration (T.sub.d), which includes duration T.sub.f=16 us
immediately followed by a slot duration of T.sub.sl=9 us , and
T.sub.f includes an idle slot duration T.sub.sl at the start of
T.sub.f. A slot duration T.sub.sl is considered to be idle if the
eNB 160 senses the channel during the slot duration, and the power
detected by the eNB 160 for at least 4 us within the slot duration
is less than an energy detection threshold X.sub.Thresh. Otherwise,
the slot duration T.sub.sl is considered to be busy.
[0063] However, since the single CCA sensing is located at a fixed
location in a subframe structure, it reduces the channel access
probability and the chance to use another region for channel
access. Therefore, although a category 2 LBT before scheduled
transmission is possible, it is too restrictive on the LBT sensing
and LAA transmission timing.
[0064] Similarly, in the case where there is no other present
unlicensed network (e.g., WiFi or LAA cells from other operators),
this approach may be used. If no other unlicensed network is
present, the LAA eNB 160 scheduler should ensure there is no
conflict between a LAA DL transmission and a LAA UL transmission.
In this case, a single CCA detection before UL transmission should
be sufficient.
[0065] The category 2 LBT is also known as a single CCA sensing of
at least 25 micro-seconds (.mu.s) before transmission. However, it
is not clear when a UE 102 can start a UL LAA transmission in a
contention access region or CCA gap. Thus, a single CCA sensing of
at least 25 .mu.s before transmission may be performed at different
locations of a CCA gap with inherent impact on the LAA UL signal
transmission. Different approaches for the single CCA sensing
timing are described.
[0066] In one approach, the single CCA sensing of at least 25 .mu.s
may be performed at the end of a CCA gap (i.e., immediately before
a scheduled UL LAA transmission with an indicated UL LAA PUSCH
format). This provides the latest channel access opportunity within
a CCA gap. For the CCA sensing interval, the UL timing advance may
be considered. Thus, the sensing interval may be based on UL timing
with the TA value adjusted, as shown in FIG. 4.
[0067] However, any unlicensed transmission that happens before and
within the CCA sensing slot may block the UL LAA transmission.
Thus, the UL LAA tends to have the lowest priority in channel
access with this approach. Because the CCA sensing is performed
immediately before a schedule UL subframe with an indicated PUSCH
format, there is no need to add an extra reservation signal or an
initial signal before the UL LAA subframe in a UL LAA
transmission.
[0068] In another approach, the single CCA sensing of at least 25
.mu.s may be performed at the beginning of a given CCA gap. In this
approach, the single CCA sensing of at least 25 .mu.s may be
performed at the beginning of a CCA gap. This provides the earliest
channel access opportunity within a CCA gap. For the sensing slot,
the UL timing advance (TA) may be considered. Thus, the sensing
slot may be based on DL timing (i.e., considering the propagation
delay of a DL transmission). For UL timing, the TA value may be
added to avoid collision with DL transmission of a previous
subframe. FIG. 5 illustrates an example of this approach.
[0069] If there is another unlicensed transmission within the CCA
sensing interval, the LBT fails, and the LAA UE 102 should defer
the contention access in the next available CCA gap. If the CCA
sensing is successful, a UL LAA UE 102 may start transmission. But
a reservation signal or initial signal has to be transmitted before
the scheduled UL PUSCH subframe to occupy the channel.
[0070] In yet another approach, the CCA sensing of at least 25
.mu.s before a UL transmission may be performed continuously in a
given CCA gap. Thus, the LBT may obtain the channel immediately
after the channel becomes idle for a continuous 25 .mu.s. This is a
more aggressive approach and provides a maximum likelihood of UL
LAA transmission. Once there is a 25 .mu.s idle interval in the CCA
gap, the UE 102 may transmit the UL LAA subframe. Similar to CCA
sensing at the beginning of a CCA gap, a reservation signal or
initial signal may have to be transmitted before the scheduled UL
PUSCH subframe to occupy the channel.
[0071] Although there are different interpretations of CCA sensing
of at least 25 .mu.s before UL transmission, the specification may
only specify one approach (e.g., at least 25 .mu.s before the UL
transmission at the OFDM symbol boundary). On the other hand, if
multiple approaches are specified, the exact approach should be
indicated in a UL scheduling DCI for a given subframe.
[0072] In a third approach, category 4 LBT may be performed. There
are many possible LBT methods for category 4 depending on how to
determine the contention window size, how to perform counter
handling, etc. The contention window size may be signed by eNB 160.
The contention window size may be adjusted based on feedback
information, such as HARQ-ACK.
[0073] In one approach, the backoff counter may be suspended if the
channel is sensed as occupied or within a defer period after an
occupied channel. Thus, the backoff counter may not be able to
reach 0 in a given CCA gap. In one method, the UL LAA LBT can be
performed with continuous backoff counter handling as in DL LAA.
The backoff counter may be extended to the next CCA gap if it is
not successful. In another method, the backoff counter and LBT
process may be reset if it there is not success in a CCA gap, and a
new LBT and backoff counter should be initiated in a new CCA
gap.
[0074] In another approach, the backoff counter may keep decreasing
regardless of the channel condition. A LAA UE 102 may transmit if
the channel is idle when the counter reaches 0. Thus, the backoff
counter decides the sensing location in a CCA gap. If the backoff
counter is determined based on the length of a CCA gap, it ensures
the LBT process can be completed in a CCA gap.
[0075] Although there are different interpretations of category 4
LBT, the specification may only specify one method. However,
several different category 4 methods may be defined. Furthermore,
for a given LBT category 4 method, different LBT parameters may be
used. Thus, the LBT category 4 method and/or LBT parameters may be
indicated in a UL scheduling DCI for a given subframe. The LBT
parameters may include the contention window size, a backoff
counter value, the backoff counter handling methods, etc.
[0076] The systems and methods herein provide for the conditions of
what LBT method and parameters should be applied under different
LAA PUSCH format and channel access conditions. In an example of a
possible UL LBT method and the corresponding CCA slot structure,
the eNB 160 may indicate a channel access scheme (e.g., whether the
above-described category 2 (also referred to as type-1 hereafter)
channel access procedure or the above-described category 4 (also
referred to as type-2 hereafter) channel access procedure).
[0077] For a type-1 channel access procedure, if a UE 102 is
indicated to perform type-1 channel access procedure for a given
subframe, the UE 102 may transmit a transmission including PUSCH in
the subframe on a carrier on which LAA Scell(s) transmission(s) are
performed, after first sensing the carrier to be idle during the
slot durations of a defer duration T.sub.d, which start at the
initial subframe boundary of the subframe and after the counter N
is zero in step 5 (below). The counter N may be adjusted by sensing
the channel for additional slot duration(s) according to the steps
below:
[0078] Step 1) set N=N.sub.init, where N.sub.init=N.sub.stored if
N.sub.stored is stored, otherwise N.sub.init is a random number
uniformly distributed between 0 and CW.sub.p, and go to step 5.
[0079] Step 2) if the slot duration exceeds the first
Single-carrier Frequency Division Multiple Access (SC-FDMA) symbol
duration of the subframe, stop and set N.sub.stored to N, else go
to 3.
[0080] Step 3) if N>0 and the UE 102 chooses to decrement the
counter, set N=N-1.
[0081] Step 4) sense the channel for an additional slot duration,
and if the additional slot duration is idle, go to step 5; else, go
to step 6.
[0082] Step 5) if N=0, stop and flush N.sub.stored; else, go to
step 2.
[0083] Step 6) sense the channel during the slot durations of an
additional defer duration T.sub.d.
[0084] Step 7) if the channel is sensed to be idle during the slot
durations of the additional defer duration T.sub.d, go to step 2;
else, go to step 6.
[0085] If a UE 102 has not transmitted a transmission including
PUSCH in the subframe on a carrier on which LAA Scell(s)
transmission(s) are performed after step 5 in the procedure above,
the UE 102 may drop the PUSCH transmission in the subframe on the
carrier.
[0086] The defer duration T.sub.d includes duration 16
us.ltoreq.T.sub.f.ltoreq.16 us+T.sub.s immediately followed by
m.sub.p consecutive slot durations where each slot duration is 9
us.ltoreq.T.sub.sl.ltoreq.9 us+T.sub.s, and T.sub.f includes an
idle slot duration T.sub.sl at the start of T.sub.f. Table 1
provides a channel access priority class.
TABLE-US-00001 TABLE 1 Channel Access Priority Class Allowed (p)
m.sub.p CW.sub.min,p CW.sub.max,p T.sub.m cot, p CW .sub.p sizes 1
1 3 7 2 ms {3,7} 2 1 7 15 3 ms {7,15} 3 3 15 63 8 or 10 ms
{15,31,63} 4 7 15 1023 8 or 10 ms {15,31,63,127,255, 511,1023}
[0087] For a type-2 channel access procedure, if a UE 102 is
indicated to perform type-2 channel access procedure for a given
subframe, the UE 102 may transmit a transmission including PUSCH in
the subframe on a carrier on which LAA Scell(s) transmission(s) are
performed immediately after sensing the carrier to be idle for at
least a sensing interval T.sub.drs=25 us which starts at the
initial subframe boundary of the subframe. T.sub.drs includes a
duration T.sub.f=16 us immediately followed by one slot duration
T.sub.sl=9 us and T.sub.f includes an idle slot duration T.sub.sl
at the start of T.sub.f. The carrier is considered to be idle for
T.sub.drs if it is sensed to be idle during the slot durations of
T.sub.drs
[0088] If a UE 102 is triggered with an SRS transmission without
PUSCH for a given subframe, the UE 102 may transmit a transmission
including SRS without PUSCH in the subframe on a carrier on which
LAA Scell(s) transmission(s) are performed immediately after
sensing the carrier to be idle for at least a sensing interval
T.sub.drs=25 us which ends right before the last SC-FDMA symbol of
the subframe.
[0089] The type-2 channel access procedure may be equivalent to the
type-1 channel access procedure with m.sub.p=1 and N=0. Therefore,
the UE 102 may have more channel access opportunities with the
type-2 channel access procedure compared to the type-1 channel
access procedure. On the other hand, with the type-2 channel access
procedure, the start timing of the transmission including PUSCH may
be able to be aligned among multiple UEs 102, and thus the type-2
channel access procedure may achieve UE multiplexing.
[0090] It should be noted that the eNB 160 may indicate the type-2
channel access procedure only for the PUSCH subframe that does not
exceed MCOT following the eNB's DL transmission or for the PUSCH
carrying UCI only. In addition, even if the UE 102 receives an UL
grant indicating a type-1 channel access procedure for a given
subframe, the UE 102 can perform a type-2 channel access procedure
for the subframe if the eNB 160 indicates, after the UL grant
reception, the use of type-2 channel access procedure for the
subframe.
[0091] LAA PUSCH formats and LBT methods are also described herein.
An LAA PUSCH may start from Discrete Fourier
Transformation-Spread-Orthogonal Frequency Division Multiplexing
(DFT-S-OFDM) symbol 0 or 1. An LAA PUSCH may end at symbol 12 or
13. Any combination of above options can be enabled by dynamic
signaling. The LAA PUSCH format of a UL LAA subframe may be
indicated in the corresponding UL grant. For multiple subframe
scheduling, the same PUSCH format may be signaled for all
subframes, or the PUSCH format of each subframe may be configured
independently.
[0092] Similarly, the channel access method (i.e., the LBT method)
may also be indicated in a UL grant DCI. The LBT method may be
configured jointly with or independently from the PUSCH formats.
However, there are some inherent relationships between the LBT
method and PUSCH format. In some cases, the LBT method or PUSCH
format cannot be performed as indicated. In these cases, some
special handlings may be needed.
[0093] The use cases of different LAA PUSCH formats are summarized
in the following description. Also, potential LBT methods that can
be applied at each LAA PUSCH format are described. Furthermore, the
mechanisms to apply the appropriate LBT and/or PUSCH structure
under different conditions are discussed.
[0094] The LBT method may be indicated for a UL LAA transmission.
For eLAA uplink LAA transmissions, different LBT methods may be
signaled for different LAA subframes. In a multiple subframe
scheduling, the same LBT method may be indicated for all subframes,
or a different LBT method can be indicated for each subframe in a
multiple subframe scheduling. Furthermore, the LBT method for each
subframe may be determined implicitly by the indicated LAA PUSCH
format.
[0095] There may be 4 possible LAA PUSCH formats. In a first format
(Format 1), an LAA PUSCH may start at DFT-S-OFDM symbol 0 and
transmit up to DFT-S-OFDM symbol 13 (No blank symbol in the LAA
subframe). In a second format (Format 2), an LAA PUSCH may start at
DFT-S-OFDM symbol 0 and transmit up to DFT-S-OFDM symbol 12 (the
last symbol (symbol 13) is blank in the LAA subframe). Both format
1 and format 2 do not have a blank symbol at the beginning of the
subframe. These two formats may be used for a single UL LAA
subframe, or the initial UL LAA subframe in a burst of UL LAA
subframes, or a continuous LAA UL subframe within a LAA UL burst.
The cases with these formats are further discussed below.
[0096] In a first case (Case 1), LBT needs to be performed. In this
case, the scheduled UL LAA subframe may be a single UL LAA
subframe, or the initial UL LAA subframe in a burst of UL LAA
subframes, or a subframe in the middle of a UL LAA burst where the
previous subframe is indicated with the last symbol (symbol 13)
blanked. This may be useful for simultaneous UL LAA transmissions
from multiple LAA UEs 102.
[0097] In all these cases, LBT has to be performed, as shown in
FIG. 6. The LBT process should be performed in the last symbol
(symbol 13) space of the previous subframe (i.e., the UE 102
assumes that the last symbol (symbol 13) of the previous subframe
can be used for channel access). The eNB 160 should make sure the
last symbol (symbol 13) of the previous subframe of the scheduled
UL LAA subframe is not occupied. The previous subframe may be a
partial DL subframe, or a UL LAA subframe with the last symbol
(symbol 13) punctured for the same or different UEs 102.
[0098] In one implementation, the UL grant may not indicate the LBT
method for the given UL LAA subframe. The LBT method may be
determined based on whether it is within the MCOT of an eNB 160
transmission. If the scheduled UL LAA subframe is within the MCOT
of an eNB 160 transmission, a single CCA sensing of at least 25
.mu.s may be applied before the UL LAA subframe transmission. If
the scheduled UL LAA subframe is outside of the MCOT of an eNB 160
transmission, a category 4 LBT may be applied before the UL LAA
subframe transmission.
[0099] In another implementation, the UL grant may indicate the LBT
method for the given UL LAA subframe. The LAA UE 102 should follow
the indicated LBT method for channel access. That is, if a single
CCA sensing of at least 25 .mu.s before transmission is indicated,
the single CCA sensing should be applied regardless whether the UL
LAA transmission is within or outside a MCOT of an eNB 160
transmission. Similarly, if a category 4 LBT is indicated, the
category 4 LBT should be applied regardless whether the UL LAA
transmission is within or outside a MCOT of an eNB 160
transmission. In the case when multiple LAA UE 102 transmissions
are scheduled, the same LBT method and/or parameters should be
signaled to participating LAA UEs 102.
[0100] In another approach, even if a category 4 LBT is indicated,
if the scheduled UL LAA subframe is within the MCOT of an eNB 160
transmission, a single CCA sensing of at least 25 .mu.s may be
applied before the UL LAA subframe transmission. If the scheduled
UL LAA subframe is outside of the MCOT of an eNB 160 transmission,
a category 4 LBT may be applied before the UL LAA subframe
transmission.
[0101] If the eNB 160 schedules multiple LAA UL transmissions from
multiple UEs 102, the same LBT method and the LBT parameters, such
as contention window size and backoff counter values etc., should
be signaled to all participating UEs 102.
[0102] In a second case (Case 2), LBT may or may not be needed. If
the scheduled UL LAA subframe is a continuous transmission within a
LAA UL burst and the previous UL LAA subframe does not have the
last symbol (symbol 13) blanked, whether an LBT is required or not
depends on whether the previous LAA transmission is successful or
not. Since the subframe is in the middle of a continuous LAA burst
transmission, the LBT method may or may not be indicated.
[0103] If the LBT method is indicated, as a continuous LAA
transmission, LBT may not be needed if the previous UL LAA subframe
is transmitted, as shown in FIG. 7. If no LBT method is indicated,
LBT may still be performed if the previous LAA subframe is not
transmitted due to a failed LBT in an earlier time.
[0104] Thus, if the LBT method is not indicated in a UL grant, the
UE 102 behavior may be specified when the previous UL LAA subframe
transmission fails. If the LBT method is indicated, it may be used
in case of fallback operation when the previous LAA UL transmission
fails. However, the detailed UE 102 behavior should be clarified
(e.g., what LBT method should be used and where the CCA gap is
assumed for LBT channel access).
[0105] Regardless of the LBT method, there are several different
options to determine the CCA gap for contention access, as
described below and as shown in FIG. 8. In a first option (Option
1), the LBT is performed in the last symbol (symbol 13) space of
the previous subframe. The UE 102 may assume the last symbol
(symbol 13) space of the previous subframe is used for channel
access and performs LBT. The simplest method may be a single CCA
sensing of at least 25 .mu.s immediately before the scheduled
transmission subframe boundary.
[0106] In a more complicated method, if the LBT method is indicated
in the UL grant for the given UL LAA subframe, the given LBT method
may be used. The LBT category 4 parameters may be based on a CCA
gap of one symbol space. If the LBT method is not indicated in the
UL grant for the given UL LAA subframe, the LBT method may be
determined based on whether it is within the MCOT of an eNB 160
transmission. If the scheduled UL LAA subframe is within the MCOT
of an eNB 160 transmission, a single CCA sensing of at least 25
.mu.s may be applied before the UL LAA subframe transmission. If
the scheduled UL LAA subframe is outside of the MCOT of an eNB 160
transmission, a category 4 LBT may be applied before the UL LAA
subframe transmission. The LBT category 4 parameters should be
based on a CCA gap of one symbol space.
[0107] In a second option (Option 2), the LBT is performed in the
first symbol (symbol 0) space of the scheduled subframe. Since the
previous LAA subframe LBT failed, the UE 102 may puncture the first
symbol (symbol 0) space of the scheduled subframe for channel
access and LBT. This provides a self-contained contention access
region that is independent of previous subframe structure and
transmissions. With option 2, the scheduled UL LAA subframe
structure has to be modified by puncturing the first symbol (symbol
0).
[0108] The simplest method may be a single CCA sensing of at least
25 .mu.s immediately before the scheduled transmission subframe
symbol 1 boundary. In a more complicated method, if the LBT method
is indicated in the UL grant for the given UL LAA subframe, the
given LBT method may be used. The LBT category 4 parameters may be
based on a CCA gap of one symbol space. If the LBT method is not
indicated in the UL grant for the given UL LAA subframe, the LBT
method may be determined based on whether it is within the MCOT of
an eNB 160 transmission. If the scheduled UL LAA subframe is within
the MCOT of an eNB 160 transmission, a single CCA sensing of at
least 25 .mu.s may be applied before the UL LAA subframe
transmission. If the scheduled UL LAA subframe is outside of the
MCOT of an eNB 160 transmission, a category 4 LBT may be applied
before the UL LAA subframe transmission. The LBT category 4
parameters may be based on a CCA gap of one symbol space.
[0109] In a third option (Option 3), the LBT is performed in the
last symbol (symbol 13) space of the previous subframe and the
first symbol (symbol 0) space of the scheduled subframe. Since the
previous LAA subframe LBT failed, the UE 102 may adjust the LBT and
may assume that a larger CCA gap should be used. Thus, the UE 102
may use the space of the last symbol (symbol 13) of the previous
subframe and puncture the first symbol (symbol 0) space of the
scheduled subframe for channel access and LBT. With option 3, the
scheduled UL LAA subframe structure has to be modified by
puncturing the first symbol (symbol 0).
[0110] If the LBT method is indicated in the UL grant for the given
UL LAA subframe, the given LBT method may be used. The LBT category
4 parameters may be based on a CCA gap of two symbol spaces. If the
LBT method is not indicated in the UL grant for the given UL LAA
subframe, the LBT method may be determined based on whether it is
within the MCOT of an eNB 160 transmission. If the scheduled UL LAA
subframe is within the MCOT of an eNB 160 transmission, a single
CCA sensing of at least 25 .mu.s may be applied before the UL LAA
subframe transmission. If the scheduled UL LAA subframe is outside
of the MCOT of an eNB 160 transmission, a category 4 LBT may be
applied before the UL LAA subframe transmission. The LBT category 4
parameters may be based on a CCA gap of two symbol space.
[0111] In a fourth option (Option 4), a two-step LBT may be
performed in the last symbol (symbol 13) space of the previous
subframe and the first symbol (symbol 0) space of the scheduled
subframe. Since the previous LAA subframe LBT failed, the UE 102
may adjust the LBT and assume a larger CCA gap should be used.
Thus, the UE 102 may use the space of last symbol (symbol 13) of
the previous subframe and puncture the first symbol (symbol 0)
space of the scheduled subframe for channel access and LBT.
However, to reduce the impact of PUSCH format change, the LBT may
be performed in two steps.
[0112] First, an LBT may be performed in the space of the last
symbol (symbol 13) of the previous subframe. If successful, the
scheduled LAA UL subframe can be transmitted with the indicated LAA
PUSCH format. If the LBT in the space of the last symbol (symbol
13) of the previous subframe fails, a second LBT may be performed
in the space of the first symbol (symbol 0) of the scheduled
subframe. If the second LBT succeeds, the scheduled LAA UL subframe
may be transmitted with a modified PUSCH format by puncturing the
first symbol (symbol 0).
[0113] Thus, with option 4, the scheduled subframe structure does
not need to be modified if the LBT in the last symbol (symbol 13)
of the previous subframe is successful, the scheduled UL LAA
subframe structure needs to be modified by puncturing the first
symbol (symbol 0) if the LBT in the last symbol (symbol 13) of the
previous subframe fails and a second LBT is performed in the first
symbol (symbol 0) of the scheduled subframe. Compared with Option 1
and Option 2 above, Option 4 provides more channel access
opportunities and a longer CCA gap for channel access. Compared
with Option 3, Option 4 provides more channel access opportunities
and reduces the chance of a modified PUSCH format.
[0114] If the LBT method is indicated in the UL grant for the given
UL LAA subframe, the given LBT method may be used. The LBT category
4 parameters may be based on a CCA gap of one symbol spaces. If the
LBT method is not indicated in the UL grant for the given UL LAA
subframe, the LBT method may be determined based on whether it is
within the MCOT of an eNB 160 transmission. If the scheduled UL LAA
subframe is within the MCOT of an eNB 160 transmission, a single
CCA sensing of at least 25 .mu.s may be applied before the UL LAA
subframe transmission. If the scheduled UL LAA subframe is outside
of the MCOT of an eNB 160 transmission, a category 4 LBT may be
applied before the UL LAA subframe transmission. The LBT category 4
parameters should be based on a CCA gap of one symbol space.
[0115] In a third format (Format 3), an LAA PUSCH may start at
DFT-S-OFDM symbol 1 and transmit up to DFT-S-OFDM symbol 13. In
Format 3, the first symbol (symbol 0) in the LAA subframe is
blank.
[0116] In a fourth format (Format 4), an LAA PUSCH may start at
DFT-S-OFDM symbol 1 and transmit up to DFT-S-OFDM symbol 12. In
Format 4, the first and the last symbol (symbol 13) are blank in
the LAA subframe.
[0117] Both format 3 and format 4 have a blank symbol at the
beginning of the subframe. These two formats may be used for a
single UL LAA subframe, or the initial UL LAA subframe in a burst
of UL LAA subframes, or a continuous LAA UL subframe within a LAA
UL burst especially when some simultaneous transmissions from other
LAA UEs 102 are scheduled.
[0118] For the LBT with LAA PUSCH format 3 and Format 4, several
options are described. In a first option (Option 1), LBT is only
performed in the first symbol (symbol 0) of the scheduled UL LAA
subframe. Since a CCA gap is included in the first symbol (symbol
0) of the scheduled UL subframe, the LBT can be limited to the
space of the first symbol (symbol 0) in all cases.
[0119] If the LBT method is indicated in the UL grant for the given
UL LAA subframe, the given LBT method should be used. The LBT
category 4 parameters may be based on a CCA gap of one symbol
spaces.
[0120] If the LBT method is not indicated in the UL grant for the
given UL LAA subframe, the LBT method may be determined based on
whether it is within the MCOT of an eNB 160 transmission. If the
scheduled UL LAA subframe is within the MCOT of an eNB 160
transmission, a single CCA sensing of at least 25 .mu.s may be
applied before the UL LAA subframe transmission. If the scheduled
UL LAA subframe is outside of the MCOT of an eNB 160 transmission,
a category 4 LBT may be applied before the UL LAA subframe
transmission. The LBT category 4 parameters may be based on a CCA
gap of one symbol space.
[0121] Furthermore, if the eNB 160 schedules multiple LAA UL
transmissions from multiple UEs 102, the same LBT method and the
LBT parameters (e.g., contention window size, backoff counter
values, etc.) may be signaled to all participating UEs 102.
[0122] In a second option (Option 2), the contention access region
and LBT may be determined by the last symbol (symbol 13) of the
previous subframe as well. In option 2, the contention access
region and LBT should consider the last symbol (symbol 13) of the
previous subframe as well. The blanked last symbol (symbol 13) of
the previous subframe and blanked first symbol (symbol 0) of a
scheduled subframe provide a longer contention access region or CCA
gap. Thus, the LBT parameters may be better adjusted to the channel
occupancy and congestion conditions.
[0123] If the last symbol (symbol 13) of the previous subframe is
not blanked for channel access, the contention access and LBT
method can be the same as in Option 1 above. On the other hand, if
the last symbol (symbol 13) of the previous subframe is also
blanked for channel access, a two-symbol CCA gap can be used for
contention access. The UE 102 may use the indicated LAA PUSCH
format even if LBT is successful in the last symbol (symbol 13) of
the previous subframe. Thus, the UE 102 may always follow the
indicated LAA PUSCH format in all cases.
[0124] If the LBT method is indicated in the UL grant for the given
UL LAA subframe, the given LBT method may be used. The LBT category
4 parameters may be based on a CCA gap of two symbol spaces. If the
LBT method is not indicated in the UL grant for the given UL LAA
subframe, the LBT method may be determined based on whether it is
within the MCOT of an eNB 160 transmission. If the scheduled UL LAA
subframe is within the MCOT of an eNB 160 transmission, a single
CCA sensing of at least 25 .mu.s may be applied before the UL LAA
subframe transmission. If the scheduled UL LAA subframe is outside
of the MCOT of an eNB 160 transmission, a category 4 LBT may be
applied before the UL LAA subframe transmission. The LBT category 4
parameters should be based on a CCA gap of two symbol space.
[0125] Furthermore, if the eNB 160 schedules multiple LAA UL
transmissions from multiple UEs 102, the same LBT method and LBT
parameters (e.g., contention window size, backoff counter values,
etc.) may be signaled to all participating UEs 102.
[0126] Signaling requirements for PUSCH format and LBT methods are
also described herein. Based on the discussion above, to determine
the appropriate LBT method and parameters for all LAA PUSCH
formats, the UE 102 needs to know whether the last symbol (symbol
13) of previous subframe is empty or not. Thus, 2 bits may indicate
the format of a scheduled UL LAA PUSCH subframe (i.e., whether the
first symbol (symbol 0) and/or last symbol (symbol 13) is blanked
for channel access).
[0127] Also, one extra bit may be needed to indicate whether the
last symbol (symbol 13) of the previous subframe is blanked as a
CCA gap or not. In the case of multiple LAA subframe scheduling, if
all UL LAA subframes are scheduled in a single DCI, the UE 102 may
know the structure of the previous subframe, thus no extra bit is
needed to indicate the availability of the last symbol of the
previous subframe.
[0128] The LAA PUSCH format and the length of the CCA gap may
impact the LBT method and parameters for the given subframe. In one
approach, the LBT method and parameters are signaled for every UL
LAA subframe. In a continuous UL LAA subframe in a burst where
there is no CCA gap reserved before the scheduled subframe, the UE
102 may transmit the UL LAA subframe without LBT if the previous
LAA UL subframe is transmitted (i.e., ignore the indicated LBT and
parameters). The indicated LBT and parameters may be applied if the
previous LAA UL subframe is not transmitted due to LBT failure.
[0129] If the eNB 160 schedules multiple LAA UL transmissions from
multiple UEs 102, the same LBT method and the LBT parameters (e.g.,
contention window size, backoff counter values, etc.) may be
signaled to all participating UEs 102.
[0130] In another approach, the LBT method may not be signaled. The
UE 102 may determine the LBT methods and LBT parameters based on
the location of the scheduled LAA UL subframe and the indicated
PUSCH format and the length of the CCA gap. For example, for a
category 4 LBT, the contention window size may be determined
dynamically based on the length of the CCA gap. If the eNB 160
schedules multiple LAA UL transmissions from multiple UEs 102, the
participating UEs 102 should have the same understanding on the LBT
method and the LBT parameters in the given UL LAA subframe.
[0131] The UE operations module 124 may provide information 148 to
the one or more receivers 120. For example, the UE operations
module 124 may inform the receiver(s) 120 when to receive
retransmissions.
[0132] The UE operations module 124 may provide information 138 to
the demodulator 114. For example, the UE operations module 124 may
inform the demodulator 114 of a modulation pattern anticipated for
transmissions from the eNB 160.
[0133] The UE operations module 124 may provide information 136 to
the decoder 108. For example, the UE operations module 124 may
inform the decoder 108 of an anticipated encoding for transmissions
from the eNB 160.
[0134] The UE operations module 124 may provide information 142 to
the encoder 150. The information 142 may include data to be encoded
and/or instructions for encoding. For example, the UE operations
module 124 may instruct the encoder 150 to encode transmission data
146 and/or other information 142. The other information 142 may
include PDSCH HARQ-ACK information.
[0135] The encoder 150 may encode transmission data 146 and/or
other information 142 provided by the UE operations module 124. For
example, encoding the data 146 and/or other information 142 may
involve error detection and/or correction coding, mapping data to
space, time and/or frequency resources for transmission,
multiplexing, etc. The encoder 150 may provide encoded data 152 to
the modulator 154.
[0136] The UE operations module 124 may provide information 144 to
the modulator 154. For example, the UE operations module 124 may
inform the modulator 154 of a modulation type (e.g., constellation
mapping) to be used for transmissions to the eNB 160. The modulator
154 may modulate the encoded data 152 to provide one or more
modulated signals 156 to the one or more transmitters 158.
[0137] The UE operations module 124 may provide information 140 to
the one or more transmitters 158. This information 140 may include
instructions for the one or more transmitters 158. For example, the
UE operations module 124 may instruct the one or more transmitters
158 when to transmit a signal to the eNB 160. For instance, the one
or more transmitters 158 may transmit during a UL subframe. The one
or more transmitters 158 may upconvert and transmit the modulated
signal(s) 156 to one or more eNBs 160.
[0138] The eNB 160 may include one or more transceivers 176, one or
more demodulators 172, one or more decoders 166, one or more
encoders 109, one or more modulators 113, a data buffer 162 and an
eNB operations module 182. For example, one or more reception
and/or transmission paths may be implemented in an eNB 160. For
convenience, only a single transceiver 176, decoder 166,
demodulator 172, encoder 109 and modulator 113 are illustrated in
the eNB 160, though multiple parallel elements (e.g., transceivers
176, decoders 166, demodulators 172, encoders 109 and modulators
113) may be implemented.
[0139] The transceiver 176 may include one or more receivers 178
and one or more transmitters 117. The one or more receivers 178 may
receive signals from the UE 102 using one or more antennas 180a-n.
For example, the receiver 178 may receive and downconvert signals
to produce one or more received signals 174. The one or more
received signals 174 may be provided to a demodulator 172. The one
or more transmitters 117 may transmit signals to the UE 102 using
one or more antennas 180a-n. For example, the one or more
transmitters 117 may upconvert and transmit one or more modulated
signals 115.
[0140] The demodulator 172 may demodulate the one or more received
signals 174 to produce one or more demodulated signals 170. The one
or more demodulated signals 170 may be provided to the decoder 166.
The eNB 160 may use the decoder 166 to decode signals. The decoder
166 may produce one or more decoded signals 164, 168. For example,
a first eNB-decoded signal 164 may comprise received payload data,
which may be stored in a data buffer 162. A second eNB-decoded
signal 168 may comprise overhead data and/or control data. For
example, the second eNB-decoded signal 168 may provide data (e.g.,
PDSCH HARQ-ACK information) that may be used by the eNB operations
module 182 to perform one or more operations.
[0141] In general, the eNB operations module 182 may enable the eNB
160 to communicate with the one or more UEs 102. The eNB operations
module 182 may include one or more of a UL LAA PUSCH format
signaling and contention access module 194.
[0142] The UL LAA PUSCH format signaling and contention access
module 194 may perform UL LAA PUSCH format signaling and contention
access operations. This may be accomplished as described above.
[0143] The eNB operations module 182 may provide information 188 to
the demodulator 172. For example, the eNB operations module 182 may
inform the demodulator 172 of a modulation pattern anticipated for
transmissions from the UE(s) 102.
[0144] The eNB operations module 182 may provide information 186 to
the decoder 166. For example, the eNB operations module 182 may
inform the decoder 166 of an anticipated encoding for transmissions
from the UE(s) 102.
[0145] The eNB operations module 182 may provide information 101 to
the encoder 109. The information 101 may include data to be encoded
and/or instructions for encoding. For example, the eNB operations
module 182 may instruct the encoder 109 to encode information 101,
including transmission data 105.
[0146] The encoder 109 may encode transmission data 105 and/or
other information included in the information 101 provided by the
eNB operations module 182. For example, encoding the data 105
and/or other information included in the information 101 may
involve error detection and/or correction coding, mapping data to
space, time and/or frequency resources for transmission,
multiplexing, etc. The encoder 109 may provide encoded data 111 to
the modulator 113. The transmission data 105 may include network
data to be relayed to the UE 102.
[0147] The eNB operations module 182 may provide information 103 to
the modulator 113. This information 103 may include instructions
for the modulator 113. For example, the eNB operations module 182
may inform the modulator 113 of a modulation type (e.g.,
constellation mapping) to be used for transmissions to the UE(s)
102. The modulator 113 may modulate the encoded data 111 to provide
one or more modulated signals 115 to the one or more transmitters
117.
[0148] The eNB operations module 182 may provide information 192 to
the one or more transmitters 117. This information 192 may include
instructions for the one or more transmitters 117. For example, the
eNB operations module 182 may instruct the one or more transmitters
117 when to (or when not to) transmit a signal to the UE(s) 102.
The one or more transmitters 117 may upconvert and transmit the
modulated signal(s) 115 to one or more UEs 102.
[0149] It should be noted that a DL subframe may be transmitted
from the eNB 160 to one or more UEs 102 and that a UL subframe may
be transmitted from one or more UEs 102 to the eNB 160.
Furthermore, both the eNB 160 and the one or more UEs 102 may
transmit data in a standard special subframe.
[0150] It should also be noted that one or more of the elements or
parts thereof included in the eNB(s) 160 and UE(s) 102 may be
implemented in hardware. For example, one or more of these elements
or parts thereof may be implemented as a chip, circuitry or
hardware components, etc. It should also be noted that one or more
of the functions or methods described herein may be implemented in
and/or performed using hardware. For example, one or more of the
methods described herein may be implemented in and/or realized
using a chipset, an application-specific integrated circuit (ASIC),
a large-scale integrated circuit (LSI) or integrated circuit,
etc.
[0151] FIG. 2 is a flow diagram illustrating a method 200 for PUSCH
format signaling and contention access by a UE 102. The UE 102 may
communicate with one or more eNBs 160 in a wireless communication
network. In one implementation, the wireless communication network
may include an LTE network.
[0152] The UE 102 may receive 202 an uplink (UL) grant for one or
more UL LAA subframes from one or more downlink control information
(DCI). A UL grant may be a DCI format in a PDCCH or EPDCCH, or
PHICH feedback.
[0153] The UE 102 may determine 204 the UL LAA physical uplink
shared channel (PUSCH) format or structure for a UL LAA subframe.
The UL grant DCI may indicate the LAA PUSCH format of the scheduled
subframe and information about the availability of the last symbol
of the previous subframe. The UL LAA PUSCH format or structure for
a UL LAA subframe may start from symbol 0 or 1 and may end at
symbol 12 or symbol 13. In an implementation, the UL LAA PUSCH may
start at symbol 0 and the last symbol of the previous subframe is
not blank.
[0154] The UE 102 may determine 206 whether listen before talk
(LBT) is needed for a scheduled LAA PUSCH. When the previous LAA
subframe transmission is successful, the UE 102 may transmit the
scheduled LAA PUSCH without LBT.
[0155] If needed, the UE 102 may determine 208 a UL contention
access region based on the UL grant for a UL LAA subframe. The
contention access region may be determined based on the indicated
LAA PUSCH structure. The contention access region may be determined
based on the indicated LAA PUSCH structure and whether the last
symbol of the previous subframe is blank. The UE 102 may determine
210 a UL contention access method in the contention access
region.
[0156] The UE 102 may also perform 212 UL contention access in the
UL contention access region. For example, the UE 102 may perform
LBT in the UL contention access region. The UE 102 may transmit 214
the LAA PUSCH if channel access succeeds.
[0157] FIG. 3 illustrates the hidden node problem for UL
transmission without LBT. In FIG. 3, a UE 302 may be in range of an
LAA cell 323 (e.g., an eNB 160) and another unlicensed node 325.
The other unlicensed node 325 is out of range of the LAA cell.
Therefore, it may be considered a hidden node (also referred to as
a hidden terminal).
[0158] An LAA DL transmission cannot avoid the hidden node issue
observed at a UE 302 because the channel observed at the eNB 160
and the UE 302 may be different. The LAA cell 323 may send a DL LAA
transmission 329 followed by the minimum gap 327 for a UL
transmission without LBT.
[0159] The UE 302 may have a scheduled UL LAA transmission 331.
However, there may be other unlicensed transmissions 333 near the
UE 302 that are not detected by the LAA eNB 160. If the UE 302
transmits without sensing, it will cause collision to an ongoing
unlicensed transmission 333.
[0160] FIG. 4 is a diagram illustrating a category 2 UL LAA
transmission. The category 2 LBT may be performed before a
scheduled UL transmission. Category 2 LBT only requires a single
CCA sensing before transmission. This may occur in a CCA sensing
interval 437 that precedes the UL subframe boundary 439. This is
also called frame based equipment (FBE) contention access.
[0161] As shown in FIG. 4, a scheduled LAA UE 102 performs CCA
detection in a single CCA sensing interval 437 upon the scheduled
UL subframe boundary 439. If the channel is idle, the LAA UE 102
can transmit the LAA UL subframe 441 as scheduled. Otherwise, the
UL transmission is dropped.
[0162] FIG. 5 illustrates an example a single clear channel
assessment (CCA) sensing of at least 25 .mu.s at the beginning of a
CCA gap. As shown in FIG. 5, the propagation delay is represented
as .delta.. The TA value will be 2.delta. and the CCA sensing
interval 545 may be aligned with the DL symbol boundary 543
including the propagation delay.
[0163] If there is another unlicensed transmission within the CCA
sensing interval 545, the LBT fails, and the LAA UE 102 should
defer the contention access in the next available CCA gap. If the
CCA sensing is successful, a UL LAA UE 102 may start transmission.
But a reservation signal 549 or initial signal may be transmitted
before the scheduled UL LAA subframe 551 (e.g., PUSCH) to occupy
the channel.
[0164] FIG. 6 is a diagram illustrating implementations of an LAA
PUSCH with required LBT channel access and no blank symbol. In one
implementation, the scheduled UL LAA subframe may be a single UL
LAA subframe 651a (or the initial UL LAA subframe in a burst of UL
LAA subframes). In this implementation, the last symbol 653a of the
previous subframe may be used as a CCA gap for contention
access.
[0165] In another implementation, the scheduled UL LAA subframe may
be a subframe 651c in the middle of a UL LAA burst. In this
implementation, the previous subframe 651b may be indicated with
the last symbol 653b (symbol 13) blanked.
[0166] These implementations may be useful for simultaneous UL LAA
transmissions from multiple LAA UEs 102.
[0167] FIG. 7 is a diagram illustrating determining whether LBT is
needed by the status of a previous UL LAA subframe transmission. If
the scheduled UL LAA subframe 751 is a continuous transmission
within a LAA UL burst and the previous UL LAA subframe 751 does not
have the last symbol (symbol 13) blanked, whether a LBT is required
or not depends on whether the previous LAA transmission is
successful or not. Since the subframe 751 is in the middle of a
continuous LAA burst transmission, the LBT method may or may not be
indicated.
[0168] If the LBT method is indicated, as a continuous LAA
transmission, LBT may not be needed for a scheduled UL LAA subframe
751b if the previous UL LAA subframe 751a is transmitted. If no LBT
method is indicated, LBT may still be performed for a scheduled UL
LAA subframe 751d if the previous LAA subframe 751c is not
transmitted due to a failed LBT in an earlier time.
[0169] FIG. 8 is a diagram illustrating options for a CCA gap and
LBT in the case of a failed transmission in a previous subframe
851. Regardless of the LBT method, there are several different
options to determine the CCA gap for contention access. In these
examples, the last symbol 853 of the previous UL LAA subframe 851a,
851c, 851e, 851g is not blanked.
[0170] In a first option (Option 1), LBT for a scheduled UL LAA
subframe 851b is performed in the last symbol 853a space of the
previous subframe 851a.
[0171] In a second option (Option 2), LBT for a scheduled UL LAA
subframe 851d is performed in the first symbol 853b space of the
scheduled UL LAA subframe 851d.
[0172] In a third option (Option 3), a single LBT for the scheduled
UL LAA subframe 851f is performed in the last symbol 853c space of
the previous subframe 851e and the first symbol 853d space of the
scheduled UL LAA subframe 851f.
[0173] In a fourth option (Option 4), a two-step LBT for the
scheduled UL LAA subframe 851h is performed in the last symbol 853e
space of the previous subframe 851g and the first symbol 853f space
of the scheduled subframe UL LAA subframe 851h.
[0174] FIG. 9 is a flow diagram illustrating a method 900 for LAA
PUSCH format signaling and performing contention access.
Specifically, the method 900 illustrates PUSCH formats and whether
LBT should be performed before transmission. The method 900 may be
implemented by a UE 102. The UE 102 may communicate with one or
more eNBs 160 in a wireless communication network. In one
implementation, the wireless communication network may include an
LTE network.
[0175] The UE 102 may receive 902 a UL grant DCI for a UL LAA
PUSCH. The UL grant DCI for the LAA PUSCH transmission may indicate
the PUSCH format.
[0176] The UE 102 may determine 904 whether the indicated LAA PUSCH
format starts at DFT-S-OFDM symbol 0. The UE 102 should determine
904 whether the PUSCH starts at DFT-S-OFDM symbol 0 or symbol 1. If
the PUSCH starts 906 at DFT-S-OFDM symbol 1, then a CCA gap is
always present and the LBT should be performed 908 before the LAA
PUSCH transmission (i.e., Case 1 LBT). FIG. 10 shows options of a
Case 1 LBT method.
[0177] If the PUSCH starts at DFT-S-OFDM symbol 0, then the UE 102
may determine 910 whether a CCA gap is available before the
subframe. In other words, the UE 102 may determine 910 whether the
scheduled LAA PUSCH is a continuous UL subframe where no CCA gap is
indicated at the end of the previous subframe. A CCA gap is
available if the scheduled LAA PUSCH is a single UL subframe, an
initial UL subframe in a multiple subframe scheduling, or a
continuous UL subframe where the last symbol (symbol 13) of the
previous subframe is signaled as blank.
[0178] If the scheduled LAA PUSCH is not a continuous UL subframe
where no CCA gap is indicated at the end of the previous subframe,
then the UE 102 may perform 912 LBT for the UL LAA PUSCH
transmission (i.e., Case 2). For Case 2, the LBT is always
performed assuming the last symbol (symbol 13) of the previous
subframe is blank and used for channel access.
[0179] If the scheduled UL LAA PUSCH is a continuous UL subframe
where no CCA gap is indicated at the end of the previous subframe,
the presence of a CCA gap depends on whether the previous UL PUSCH
is transmitted successfully or not.
[0180] The UE 102 may determine 914 whether the previous LAA PUSCH
subframe transmission is successful. If the previous LAA PUSCH is
transmitted successfully from the given UE 102, the UE 102 may
transmit 916 the given UL LAA PUSCH as indicated without LBT. The
UE 102 may ignore the LBT method and/or parameters even if
indicated. If the previous LAA PUSCH is not transmitted
successfully (e.g., failed LBT), then the UE 102 may perform 918
LBT for the scheduled LAA PUSCH transmission (i.e., Case 3).
Multiple options can be used for Case 3 LBT, as shown in FIG. 11
(also illustrated in FIG. 8).
[0181] FIG. 10 is a flow diagram illustrating a method 1000 for
performing a case 1 LBT. The method 1000 may be implemented by a UE
102.
[0182] The UE 102 may determine 1002 that an LAA PUSCH starts at
symbol 1. In this case (i.e., case 1), the UE 102 may perform LBT
for the UL LAA PUSCH transmission. The UE 102 may implement one of
two options for a case 1 LBT. In one option, the UE 102 may always
perform 1004 LBT in the gap of symbol 0 of the scheduled subframe
only.
[0183] In another option, the UE 102 may determine 1006 the length
of the CCA gap for LBT based on the PUSCH format of the previous
subframe. If UE 102 determines 1008 that the last symbol (symbol
13) of the previous LAA PUSCH subframe is blank, the UE 102 may
perform 1010 LBT in the gap of symbol 13 of the previous subframe
and symbol 0 of the scheduled subframe. Otherwise, the UE 102 may
perform 1012 LBT in the gap of symbol 0 of the scheduled subframe
only.
[0184] FIG. 11 is a flow diagram illustrating a method 1100 for
performing a case 3 LBT. The method 1100 may be implemented by a UE
102.
[0185] The UE 102 may determine 1102 to perform LBT for a UL LAA
PUSCH transmission. In this example, the LBT is a case 3 LBT. If
the previous LAA PUSCH is not transmitted successfully (e.g.,
failed LBT), the UE 102 may perform LBT for the scheduled LAA PUSCH
transmission. Multiple options can be used for case 3 LBT.
[0186] In Option 1, the UE 102 may perform 1104 LBT in the last
symbol space of the previous subframe. If the UE 102 determines
1106 that the LBT is successful, the LAA PUSCH format should start
1108 at symbol 0 as signaled in the UL grant DCI. Otherwise, there
is no transmission 1110 and the LAA PUSCH is deferred to later
subframes.
[0187] In Option 2, the UE 102 may perform 1112 LBT in the first
symbol space of the scheduled subframe. If the UE 102 determines
1114 that the LBT is successful, the LAA PUSCH format should start
1116 at symbol 1 by puncturing the symbol 0 of the PUSCH format
indicated in the UL grant DCI. there is no transmission 1110 and
the LAA PUSCH is deferred to later subframes.
[0188] In Option 3, the UE 102 may perform 1118 a single LBT in the
last symbol space of previous subframe and the first symbol space
of the scheduled subframe. If the UE 102 determines 1120 that the
LBT is successful, the LAA PUSCH format should start 1116 at symbol
1 by puncturing the symbol 0 of the PUSCH format indicated in the
UL grant DCI. there is no transmission 1110 and the LAA PUSCH is
deferred to later subframes.
[0189] In Option 4, the UE 102 may perform 1122 a two-step LBT in
the last symbol space of previous subframe and the first symbol
space of the scheduled subframe. If the UE 102 determines 1124 that
the LBT is successful in the last symbol (symbol 13) of the
previous subframe, the LAA PUSCH format should start 1108 at symbol
0 as signaled in the UL grant DCI.
[0190] If LBT fails in the last symbol (symbol 13) of the previous
subframe, a second LBT may be performed in in the first symbol
(symbol 0) of the scheduled subframe. If the UE 102 determines 1126
that the LBT is successful in the first symbol (symbol 0) of the
scheduled subframe, the LAA PUSCH format should start 1116 at
symbol 1 by puncturing the symbol 0 of the PUSCH format indicated
in the UL grant DCI. there is no transmission 1110 and the LAA
PUSCH is deferred to later subframes.
[0191] FIG. 12 illustrates various components that may be utilized
in a UE 1202. The UE 1202 described in connection with FIG. 12 may
be implemented in accordance with the UE 102 described in
connection with FIG. 1. The UE 1202 includes a processor 1289 that
controls operation of the UE 1202. The processor 1289 may also be
referred to as a central processing unit (CPU). Memory 1295, which
may include read-only memory (ROM), random access memory (RAM), a
combination of the two or any type of device that may store
information, provides instructions 1291a and data 1293a to the
processor 1289. A portion of the memory 1295 may also include
non-volatile random access memory (NVRAM). Instructions 1291b and
data 1293b may also reside in the processor 1289. Instructions
1291b and/or data 1293b loaded into the processor 1289 may also
include instructions 1291a and/or data 1293a from memory 1295 that
were loaded for execution or processing by the processor 1289. The
instructions 1291b may be executed by the processor 1289 to
implement the method 200 described above.
[0192] The UE 1202 may also include a housing that contains one or
more transmitters 1258 and one or more receivers 1220 to allow
transmission and reception of data. The transmitter(s) 1258 and
receiver(s) 1220 may be combined into one or more transceivers
1218. One or more antennas 1222a-n are attached to the housing and
electrically coupled to the transceiver 1218.
[0193] The various components of the UE 1202 are coupled together
by a bus system 1297, which may include a power bus, a control
signal bus and a status signal bus, in addition to a data bus.
However, for the sake of clarity, the various buses are illustrated
in FIG. 12 as the bus system 1297. The UE 1202 may also include a
digital signal processor (DSP) 1299 for use in processing signals.
The UE 1202 may also include a communications interface 1201 that
provides user access to the functions of the UE 1202. The UE 1202
illustrated in FIG. 12 is a functional block diagram rather than a
listing of specific components.
[0194] FIG. 13 illustrates various components that may be utilized
in an eNB 1360. The eNB 1360 described in connection with FIG. 13
may be implemented in accordance with the eNB 160 described in
connection with FIG. 1. The eNB 1360 includes a processor 1389 that
controls operation of the eNB 1360. The processor 1389 may also be
referred to as a central processing unit (CPU). Memory 1395, which
may include read-only memory (ROM), random access memory (RAM), a
combination of the two or any type of device that may store
information, provides instructions 1391a and data 1393a to the
processor 1389. A portion of the memory 1395 may also include
non-volatile random access memory (NVRAM). Instructions 1391b and
data 1393b may also reside in the processor 1389. Instructions
1391b and/or data 1393b loaded into the processor 1389 may also
include instructions 1391a and/or data 1393a from memory 1395 that
were loaded for execution or processing by the processor 1389. The
instructions 1391b may be executed by the processor 1389 to
implement one or more methods described above.
[0195] The eNB 1360 may also include a housing that contains one or
more transmitters 1317 and one or more receivers 1378 to allow
transmission and reception of data. The transmitter(s) 1317 and
receiver(s) 1378 may be combined into one or more transceivers
1376. One or more antennas 1380a-n are attached to the housing and
electrically coupled to the transceiver 1376.
[0196] The various components of the eNB 1360 are coupled together
by a bus system 1397, which may include a power bus, a control
signal bus and a status signal bus, in addition to a data bus.
However, for the sake of clarity, the various buses are illustrated
in FIG. 13 as the bus system 1397. The eNB 1360 may also include a
digital signal processor (DSP) 1399 for use in processing signals.
The eNB 1360 may also include a communications interface 1301 that
provides user access to the functions of the eNB 1360. The eNB 1360
illustrated in FIG. 13 is a functional block diagram rather than a
listing of specific components.
[0197] FIG. 14 is a block diagram illustrating one implementation
of a UE 1402 in which systems and methods for PUSCH format
signaling and contention access may be implemented. The UE 1402
includes transmit means 1458, receive means 1420 and control means
1424. The transmit means 1458, receive means 1420 and control means
1424 may be configured to perform one or more of the functions
described in connection with FIG. 1 above. FIG. 12 above
illustrates one example of a concrete apparatus structure of FIG.
14. Other various structures may be implemented to realize one or
more of the functions of FIG. 1. For example, a DSP may be realized
by software.
[0198] FIG. 15 is a block diagram illustrating one implementation
of an eNB 1560 in which systems and methods for PUSCH format
signaling and contention access may be implemented. The eNB 1560
includes transmit means 1517, receive means 1578 and control means
1582. The transmit means 1517, receive means 1578 and control means
1582 may be configured to perform one or more of the functions
described in connection with FIG. 1 above. FIG. 13 above
illustrates one example of a concrete apparatus structure of FIG.
15. Other various structures may be implemented to realize one or
more of the functions of FIG. 1. For example, a DSP may be realized
by software.
[0199] The term "computer-readable medium" refers to any available
medium that can be accessed by a computer or a processor. The term
"computer-readable medium," as used herein, may denote a computer-
and/or processor-readable medium that is non-transitory and
tangible. By way of example, and not limitation, a
computer-readable or processor-readable medium may comprise RAM,
ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk
storage or other magnetic storage devices, or any other medium that
can be used to carry or store desired program code in the form of
instructions or data structures and that can be accessed by a
computer or processor. Disk and disc, as used herein, includes
compact disc (CD), laser disc, optical disc, digital versatile disc
(DVD), floppy disk and Blu-ray.RTM. disc where disks usually
reproduce data magnetically, while discs reproduce data optically
with lasers.
[0200] It should be noted that one or more of the methods described
herein may be implemented in and/or performed using hardware. For
example, one or more of the methods described herein may be
implemented in and/or realized using a chipset, an
application-specific integrated circuit (ASIC), a large-scale
integrated circuit (LSI) or integrated circuit, etc.
[0201] Each of the methods disclosed herein comprises one or more
steps or actions for achieving the described method. The method
steps and/or actions may be interchanged with one another and/or
combined into a single step without departing from the scope of the
claims. In other words, unless a specific order of steps or actions
is required for proper operation of the method that is being
described, the order and/or use of specific steps and/or actions
may be modified without departing from the scope of the claims.
[0202] It is to be understood that the claims are not limited to
the precise configuration and components illustrated above. Various
modifications, changes and variations may be made in the
arrangement, operation and details of the systems, methods, and
apparatus described herein without departing from the scope of the
claims.
[0203] A program running on the eNB 160 or the UE 102 according to
the described systems and methods is a program (a program for
causing a computer to operate) that controls a CPU and the like in
such a manner as to realize the function according to the described
systems and methods. Then, the information that is handled in these
apparatuses is temporarily stored in a RAM while being processed.
Thereafter, the information is stored in various ROMs or HDDs, and
whenever necessary, is read by the CPU to be modified or written.
As a recording medium on which the program is stored, among a
semiconductor (for example, a ROM, a nonvolatile memory card, and
the like), an optical storage medium (for example, a DVD, a MO, a
MD, a CD, a BD, and the like), a magnetic storage medium (for
example, a magnetic tape, a flexible disk, and the like), and the
like, any one may be possible. Furthermore, in some cases, the
function according to the described systems and methods described
above is realized by running the loaded program, and in addition,
the function according to the described systems and methods is
realized in conjunction with an operating system or other
application programs, based on an instruction from the program.
[0204] Furthermore, in a case where the programs are available on
the market, the program stored on a portable recording medium can
be distributed or the program can be transmitted to a server
computer that connects through a network such as the Internet. In
this case, a storage device in the server computer also is
included. Furthermore, some or all of the eNB 160 and the UE 102
according to the systems and methods described above may be
realized as an LSI that is a typical integrated circuit. Each
functional block of the eNB 160 and the UE 102 may be individually
built into a chip, and some or all functional blocks may be
integrated into a chip. Furthermore, a technique of the integrated
circuit is not limited to the LSI, and an integrated circuit for
the functional block may be realized with a dedicated circuit or a
general-purpose processor. Furthermore, if with advances in a
semiconductor technology, a technology of an integrated circuit
that substitutes for the LSI appears, it is also possible to use an
integrated circuit to which the technology applies.
[0205] Moreover, each functional block or various features of the
base station device and the terminal device used in each of the
aforementioned embodiments may be implemented or executed by a
circuitry, which is typically an integrated circuit or a plurality
of integrated circuits. The circuitry designed to execute the
functions described in the present specification may comprise a
general-purpose processor, a digital signal processor (DSP), an
application specific or general application integrated circuit
(ASIC), a field programmable gate array (FPGA), or other
programmable logic devices, discrete gates or transistor logic, or
a discrete hardware component, or a combination thereof. The
general-purpose processor may be a microprocessor, or
alternatively, the processor may be a conventional processor, a
controller, a microcontroller or a state machine. The
general-purpose processor or each circuit described above may be
configured by a digital circuit or may be configured by an analogue
circuit. Further, when a technology of making into an integrated
circuit superseding integrated circuits at the present time appears
due to advancement of a semiconductor technology, the integrated
circuit by this technology is also able to be used.
* * * * *