U.S. patent application number 16/623849 was filed with the patent office on 2021-05-13 for transmission with restrictions in unlicensed spectrum.
This patent application is currently assigned to IDAC HOLDINGS, INC.. The applicant listed for this patent is IDAC HOLDINGS, INC.. Invention is credited to Mihaela C. Beluri, Muhammad Fazili, Moon-il Lee, Arnab Roy, Janet A. Stern-Berkowitz, Kevin T. Wanuga.
Application Number | 20210144757 16/623849 |
Document ID | / |
Family ID | 1000005389108 |
Filed Date | 2021-05-13 |
United States Patent
Application |
20210144757 |
Kind Code |
A1 |
Fazili; Muhammad ; et
al. |
May 13, 2021 |
TRANSMISSION WITH RESTRICTIONS IN UNLICENSED SPECTRUM
Abstract
Systems, devices, and methods for operating in an unlicensed
band are disclosed herein. In one example, a device may receive
configuration information that includes a maximum channel occupancy
time (MCOT) and a plurality of parameters including a plurality of
transmission opportunity windows (TOWs). Based on the configuration
information, the device may split a transmission into a plurality
of bursts that may be grouped into sets of bursts based on how many
bursts fit within a TOW. The number of bursts in a set of bursts
may be less than or equal to the MCOT. The device may perform a
clear channel assessment (CCA) to determine if the channel is busy
and to determine a start time within the TOW for the bursts. The
device may then transmit the set of bursts for that TOW, where each
burst may have a burst indicator (BI).
Inventors: |
Fazili; Muhammad; (Audubon,
PA) ; Stern-Berkowitz; Janet A.; (Little Neck,
NY) ; Roy; Arnab; (Phoenixville, PA) ; Wanuga;
Kevin T.; (Souderton, PA) ; Lee; Moon-il;
(Melville, NY) ; Beluri; Mihaela C.; (Jericho,
NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IDAC HOLDINGS, INC. |
Wilmington |
DE |
US |
|
|
Assignee: |
IDAC HOLDINGS, INC.
Wilmington
DE
|
Family ID: |
1000005389108 |
Appl. No.: |
16/623849 |
Filed: |
June 22, 2018 |
PCT Filed: |
June 22, 2018 |
PCT NO: |
PCT/US2018/038915 |
371 Date: |
December 18, 2019 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62524229 |
Jun 23, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 16/14 20130101;
H04W 74/0808 20130101; H04W 74/006 20130101 |
International
Class: |
H04W 74/08 20060101
H04W074/08; H04W 16/14 20060101 H04W016/14; H04W 74/00 20060101
H04W074/00 |
Claims
1. A method for operating in an unlicensed band, comprising:
receiving configuration information that includes a maximum channel
occupancy time (MCOT) and a plurality of parameters, wherein the
plurality of parameters includes a plurality of transmission
opportunity windows (TOWs); splitting a transmission into a
plurality of bursts based on the configuration information;
performing a clear channel assessment (CCA); determining a start
time in a first TOW of the plurality of TOWs for a first set of
bursts based on the CCA and the configuration information, wherein
each set of bursts comprises one or more bursts of the plurality of
bursts; determining a number of bursts for the first set of bursts
based on the configuration information and the start time, wherein
the number of bursts of the first set of bursts is less than or
equal to the MCOT and fits into the first TOW; and transmitting the
first set of bursts at the start time for the first set of bursts
with a burst indicator (BI) for each burst of the number of
bursts.
2. The method of claim 1, further comprising performing CCA prior
to sending the first set of bursts.
3. The method of claim 1, further comprising scrambling a reference
signal (RS) with each of the BIs, wherein a density of the RS is a
function of a coverage enhancement level.
4. The method of claim 1, wherein the TOW is a grant of consecutive
subframes.
5. The method of claim 1, wherein the transmission is an uplink
transmission.
6. The method of claim 1, wherein the configuration information is
received on a control channel.
7. The method of claim 1, wherein the one or more BIs is specific
to a channel, C-RNTI, a hybrid-ARQ process ID, or a cell.
8. An apparatus for operating in an unlicensed band, the apparatus
comprising: a transceiver; a processor operatively connected to the
transceiver, the processor and transceiver configured to receive
configuration information that includes a maximum channel occupancy
time (MCOT) and a plurality of parameters, wherein the plurality of
parameters includes a plurality of transmission opportunity windows
(TOWs); the processor and transceiver further configure to split a
transmission into a plurality of bursts based on the configuration
information, perform a clear channel assessment (CCA), and
determining a start time in a first TOW of the plurality of TOWs
for a first set of bursts based on the CCA and the configuration
information, wherein each set of bursts comprises one or more
bursts of the plurality of bursts; and the processor and
transceiver further configured to determine a number of bursts for
the first set of bursts based on the configuration information and
the start time, wherein the number of bursts of the first set of
bursts is less than or equal to the MCOT and fits into the first
TOW, and transmit the first set of bursts at the start time for the
first set of bursts with a burst indicator (BI) for each burst of
the number of bursts.
9. The apparatus of claim 8, further comprising performing CCA
prior to sending the first set of bursts.
10. The apparatus of claim 8, further comprising scrambling a
reference signal (RS) with each of the BIs, wherein a density of
the RS is a function of a coverage enhancement level.
11. The apparatus of claim 8, wherein the TOW is a grant of
consecutive subframes.
12. The apparatus of claim 8, wherein the transmission is an uplink
transmission.
13. The apparatus of claim 8, wherein the configuration information
is received on a control channel.
14. The apparatus of claim 8, wherein each BI is specific to a
channel, C-RNTI, a hybrid-ARQ process ID, or a cell.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
application No. 62/524,229 filed on Jun. 23, 2017, the contents of
which is hereby incorporated by reference herein.
BACKGROUND
[0002] Cellular communication has seen a tremendous rise in demand
as more devices are capable of wireless communication and
smartphones become increasingly popular. Cellular communication may
be used to serve various markets, such as consumer phones, internet
of things, and low latency market segments to name a few. A
regulating agency may issue licenses for cellular communication
spectrum usage; however, there may be occasions where cellular
communication may occur in unlicensed spectrum. Operation in
unlicensed spectrum may need to contend with sharing spectrum with
multiple devices without a central controller by employing channel
sensing schemes.
SUMMARY
[0003] Systems, devices, and methods for operating in an unlicensed
band are disclosed herein. In one example, a device may receive
configuration information that includes a maximum channel occupancy
time (MOOT) and a plurality of parameters including a plurality of
transmission opportunity windows (TOWs). Based on the configuration
information, the device may split a transmission into a plurality
of bursts that may be grouped into sets of bursts based on how many
bursts fit within a TOW. The number of bursts in a set of bursts
may be less than or equal to the MOOT. The device may perform a
clear channel assessment (CCA) to determine if the channel is busy
and to determine a start time within the TOW for the bursts. The
device may then transmit the set of bursts for that TOW, where each
burst may have a burst indicator (BI).
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] A more detailed understanding may be had from the following
description, given by way of example in conjunction with the
accompanying drawings, wherein like reference numerals in the
figures indicate like elements, and wherein:
[0005] FIG. 1A is a system diagram of an example wireless
transmit/receive unit (WTRU) that may be used within a
communications system as discussed herein;
[0006] FIG. 1B is a system diagram of an example communications
system according to one or more embodiments;
[0007] FIG. 1C is a system diagram of an example radio access
network and an example core network that may be used within a
communications system, such as that illustrated in FIG. 1B;
[0008] FIG. 2A is an illustration of an example process of a
transmission based on available resources according to one or more
embodiments disclosed herein;
[0009] FIG. 2B is a diagram of example transmissions based on
available resources according to one or more embodiments disclosed
herein;
[0010] FIG. 3A is an illustration of an example process of a time
limited transmission for a set of allocated resources according to
one or more embodiments disclosed herein;
[0011] FIG. 3B is a diagram of example time limited transmissions
for a set of allocated resources according to one or more
embodiments disclosed herein;
[0012] FIG. 4A is an illustration of an example process for a
transmission split into burst(s) according to one or more
embodiments disclosed herein;
[0013] FIG. 4B is diagram of example transmissions using split
bursts;
[0014] FIG. 5 is a diagram of example transmissions using burst
indicators; and
[0015] FIG. 6 is an illustration of an example transmission process
using burst indicators.
DETAILED DESCRIPTION
[0016] Cellular communications may focus on several communications
device market segments such as Enhanced Mobile BroadBand (eMBB),
Ultra Reliable Low Latency Communication (URLLC) and Machine Type
Communications (MTC). The development of Internet of Things (IoT)
applications may address connectivity solutions into sensors,
actuators, meters, appliances, cars, and other devices the like.
IoT networks may have different design objectives varying from
local area coverage to wide area coverage. These networks may be
optimized to provide device coverage extension, device complexity
reductions, and long device battery life. As discussed herein, the
terms apparatus and device are interchangeable.
[0017] FIG. 1A is a device diagram of an example wireless
transmit/receive unit (WTRU) 102. The WTRU 102 may include a
processor 118, a transceiver 120, a transmit/receive element 122, a
speaker/microphone 124, a keypad 126, a display/touchpad 128,
non-removable memory 130, removable memory 132, a power source 134,
a global positioning system (GPS) chipset 136, and other
peripherals 138. It will be appreciated that the WTRU 102 may
include any sub-combination of the elements described herein while
remaining consistent with any disclosed embodiment.
[0018] The processor 118 may be a general purpose processor, a
special purpose processor, a conventional processor, a digital
signal processor (DSP), a plurality of microprocessors, one or more
microprocessors in association with a DSP core, a controller, a
microcontroller, Application Specific Integrated Circuits (ASICs),
Field Programmable Gate Array (FPGAs) circuits, any other type of
integrated circuit (IC), a state machine, and the like. The
processor 118 may perform signal coding, data processing, power
control, input/output processing, and/or any other functionality
that enables the WTRU 102 to operate in a wireless environment. The
processor 118 may be coupled to the transceiver 120, which may be
coupled to the transmit/receive element 122. While FIG. 1A depicts
the processor 118 and the transceiver 120 as separate components,
it will be appreciated that the processor 118 and the transceiver
120 may be integrated together in an electronic package or
chip.
[0019] The transmit/receive element 122 may be configured to
transmit signals to, or receive signals from, a base station (e.g.,
the base station 114a) over the air interface 116. For example, in
one embodiment, the transmit/receive element 122 may be an antenna
configured to transmit and/or receive RF signals. In another
embodiment, the transmit/receive element 122 may be an
emitter/detector configured to transmit and/or receive IR, UV, or
visible light signals, for example. In yet another embodiment, the
transmit/receive element 122 may be configured to transmit and
receive both RF and light signals. It will be appreciated that the
transmit/receive element 122 may be configured to transmit and/or
receive any combination of wireless signals.
[0020] In addition, although the transmit/receive element 122 is
depicted in FIG. 1A as a single element, the WTRU 102 may include
any number of transmit/receive elements 122. More specifically, the
WTRU 102 may employ MIMO technology. Thus, in one embodiment, the
WTRU 102 may include two or more transmit/receive elements 122
(e.g., multiple antennas) for transmitting and receiving wireless
signals over the air interface 116.
[0021] The transceiver 120 may be configured to modulate the
signals that are to be transmitted by the transmit/receive element
122 and to demodulate the signals that are received by the
transmit/receive element 122. As noted above, the WTRU 102 may have
multi-mode capabilities. Thus, the transceiver 120 may include
multiple transceivers for enabling the WTRU 102 to communicate via
multiple RATs, such as UTRA and IEEE 802.11, for example.
[0022] The processor 118 of the WTRU 102 may be coupled to, and may
receive user input data from, the speaker/microphone 124, the
keypad 126, and/or the display/touchpad 128 (e.g., a liquid crystal
display (LCD) display unit or organic light-emitting diode (OLED)
display unit). The processor 118 may also output user data to the
speaker/microphone 124, the keypad 126, and/or the display/touchpad
128. In addition, the processor 118 may access information from,
and store data in, any type of suitable memory, such as the
non-removable memory 130 and/or the removable memory 132. The
non-removable memory 130 may include random-access memory (RAM),
read-only memory (ROM), a hard disk, or any other type of memory
storage device. The removable memory 132 may include a subscriber
identity module (SIM) card, a memory stick, a secure digital (SD)
memory card, and the like. In other embodiments, the processor 118
may access information from, and store data in, memory that is not
physically located on the WTRU 102, such as on a server or a home
computer (not shown).
[0023] The processor 118 may receive power from the power source
134, and may be configured to distribute and/or control the power
to the other components in the WTRU 102. The power source 134 may
be any suitable device for powering the WTRU 102. For example, the
power source 134 may include one or more dry cell batteries (e.g.,
nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride
(NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, and
the like.
[0024] The processor 118 may also be coupled to the GPS chipset
136, which may be configured to provide location information (e.g.,
longitude and latitude) regarding the current location of the WTRU
102. In addition to, or in lieu of, the information from the GPS
chipset 136, the WTRU 102 may receive location information over the
air interface 116 from a base station (e.g., base stations 114a,
114b) and/or determine its location based on the timing of the
signals being received from two or more nearby base stations. It
will be appreciated that the WTRU 102 may acquire location
information by way of any suitable location-determination method
while remaining consistent with an embodiment.
[0025] The processor 118 may further be coupled to other
peripherals 138, which may include one or more software and/or
hardware modules that provide additional features, functionality
and/or wired or wireless connectivity. For example, the peripherals
138 may include an accelerometer, an e-compass, a satellite
transceiver, a digital camera (for photographs or video), a
universal serial bus (USB) port, a vibration device, a television
transceiver, a hands free headset, a Bluetooth.RTM. module, a
frequency modulated (FM) radio unit, a digital music player, a
media player, a video game player module, an Internet browser, and
the like.
[0026] WTRUs may operate in cellular communication networks that
may be deployed in licensed spectrum. With the increase in demand
of cellular applications, however, there may be an increase in
traffic load in the licensed spectrum, in which case operators may
have to buy more licensed spectrum in order to meet the demand of
the increased traffic load. Since license spectrum is expensive, an
alternative approach may be to offload cellular traffic to
unlicensed bands. Unlicensed spectrum bands may also be used for
non-cellular applications such as WiFi, Bluetooth, and other
wireless protocol supported applications.
[0027] FIG. 1B is a diagram of an example communications system 100
(e.g., cellular communication network) in which one or more
disclosed embodiments may be implemented. The communications system
100 may be a multiple access system that provides content, such as
voice, data, video, messaging, broadcast, etc., to multiple
wireless users. The communications system 100 may enable multiple
wireless users to access such content through the sharing of system
resources, including wireless bandwidth. For example, the
communications systems 100 may employ one or more channel access
methods, such as code division multiple access (CDMA), time
division multiple access (TDMA), frequency division multiple access
(FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), and
the like.
[0028] The term channel may be used herein to represent a data
channel, a control channel, and/or another channel or signal that
may be transmitted and/or received. A data channel may, for
example, be a physical DL shared channel (PDSCH), a narrow band
(NB)-PDSCH, a new radio (NR)-PDSCH, a physical UL data channel
(PUSCH), a NB-PUSCH, a NR-PUSCH, among others. A control channel
may, for example be a physical DL control channel (PDCCH), and
enhanced (E)-PDCCH, a NB-PDCCH, a NR-PDCCH, a physical UL control
channel (PUCCH), a NB-PUCCH, a NR-PUCCH, among others. A channel
may, for example be a random access channel such as a physical
random access channel (PRACH) or a broadcast channel such as a
physical broadcast channel (PBCH). The term channel may be used
herein to represent a frequency or operating channel that may be
used for transmission and/or reception. A channel may be free or
busy, but should be free before transmission on the channel. A
common channel may be a control channel such as a DL control
channel, a paging channel, a broadcast channel, a shared channel
that may carry common information such as a random access response
(RAR), a paging channel or message, and/or system information,
among others.
[0029] As shown in FIG. 1B, the communications system 100 may
include a number of interactive elements, such as wireless
transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a radio
access network (RAN) 104, a core network 106, a public switched
telephone network (PSTN) 108, the Internet 110, and other networks
112, though it will be appreciated that the disclosed embodiments
contemplate any number of WTRUs, base stations, networks, and/or
network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be
any type of device configured to operate and/or communicate in a
wireless environment. By way of example, the WTRUs 102a, 102b,
102c, 102d may be configured to transmit and/or receive wireless
signals and may include user equipment (UE), a mobile station, a
fixed or mobile subscriber unit, a pager, a cellular telephone, a
personal digital assistant (PDA), a smartphone, a laptop, a
netbook, a personal computer, a wireless sensor, consumer
electronics, and the like.
[0030] The communications systems 100 may also include a base
station 114a and a base station 114b. Each of the base stations
114a, 114b may be any type of device configured to wirelessly
interface with at least one of the WTRUs 102a, 102b, 102c, 102d to
facilitate access to one or more communication networks, such as
the core network 106, the Internet 110, and/or the other networks
112. By way of example, the base stations 114a, 114b may be a base
transceiver station (BTS), a Node-B, an eNode B (eNB), a Home Node
B, a Home eNode B, a site controller, an access point (AP), a
wireless router, gNB, TRP, STA, cell, and the like, and may be used
interchangeably herein. While the base stations 114a, 114b are each
depicted as a single element, it will be appreciated that the base
stations 114a, 114b may include/represent any number of
interconnected base stations and/or network elements. Similarly, as
discussed herein, reference to an eNB may be used to represent one
or more of a gNB, TRP, STA, cell, base station, and/or the like.
The individual elements that constitute nodes on a network may be
considered to be devices, such as a base station or WTRU.
[0031] The base station 114a may be part of the RAN 104, which may
also include other base stations and/or network elements (not
shown), such as a base station controller (BSC), a radio network
controller (RNC), relay nodes, etc. The base station 114a and/or
the base station 114b may be configured to transmit and/or receive
wireless signals within a particular geographic region, which may
be referred to as a cell (not shown). The cell may further be
divided into cell sectors. For example, the cell associated with
the base station 114a may be divided into three sectors. Thus, in
one embodiment, the base station 114a may include three
transceivers, i.e., one for each sector of the cell. In another
embodiment, the base station 114a may employ multiple-input
multiple-output (MIMO) technology and, therefore, may utilize
multiple transceivers for each sector of the cell.
[0032] The base stations 114a, 114b may communicate with one or
more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116,
which may be any suitable wireless communication link (e.g., radio
frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible
light, etc.). The air interface 116 may be established using any
suitable radio access technology (RAT).
[0033] More specifically, as noted above, the communications system
100 may be a multiple access system and may employ one or more
channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA,
and the like. For example, the base station 114a in the RAN 104 and
the WTRUs 102a, 102b, 102c may implement a radio technology such as
Universal Mobile Telecommunications System (UMTS) Terrestrial Radio
Access (UTRA), which may establish the air interface 116 using
wideband CDMA (WCDMA). WCDMA may include communication protocols
such as High-Speed Packet Access (HSPA) and/or Evolved HSPA
(HSPA+). HSPA may include High-Speed Downlink Packet Access (HSDPA)
and/or High-Speed Uplink Packet Access (HSUPA).
[0034] In another embodiment, the base station 114a and the WTRUs
102a, 102b, 102c may implement a radio technology such as Evolved
UMTS Terrestrial Radio Access (E-UTRA), which may establish the air
interface 116 using Long Term Evolution (LTE) and/or LTE-Advanced
(LTE-A).
[0035] In other embodiments, the base station 114a and the WTRUs
102a, 102b, 102c may implement radio technologies such as IEEE
802.16 (i.e., Worldwide Interoperability for Microwave Access
(WiMAX)), CDMA2000, CDMA2000 1x, CDMA2000 EV-DO, Interim Standard
2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856
(IS-856), Global System for Mobile communications (GSM), Enhanced
Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), and the
like.
[0036] The base station 114b in FIG. 1B may be a wireless router,
Home Node B, Home eNode B, or access point, for example, and may
utilize any suitable RAT for facilitating wireless connectivity in
a localized area, such as a place of business, a home, a vehicle, a
campus, and the like. In one embodiment, the base station 114b and
the WTRUs 102c, 102d may implement a radio technology such as IEEE
802.11 to establish a wireless local area network (WLAN). In
another embodiment, the base station 114b and the WTRUs 102c, 102d
may implement a radio technology such as IEEE 802.15 to establish a
wireless personal area network (WPAN). In yet another embodiment,
the base station 114b and the WTRUs 102c, 102d may utilize a
cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.)
to establish a picocell or femtocell. As shown in FIG. 1B, the base
station 114b may have a direct connection to the Internet 110.
Thus, the base station 114b may not be required to access the
Internet 110 via the core network 106.
[0037] The RAN 104 may be in communication with the core network
106, which may be any type of network configured to provide voice,
data, applications, and/or voice over internet protocol (VoIP)
services to one or more of the WTRUs 102a, 102b, 102c, 102d. For
example, the core network 106 may provide call control, billing
services, mobile location-based services, pre-paid calling,
Internet connectivity, video distribution, etc., and/or perform
high-level security functions, such as user authentication.
Although not shown in FIG. 1B, it will be appreciated that the RAN
104 and/or the core network 106 may be in direct or indirect
communication with other RANs that employ the same RAT as the RAN
104 or a different RAT. For example, in addition to being connected
to the RAN 104, which may be utilizing an E-UTRA radio technology,
the core network 106 may also be in communication with another RAN
(not shown) employing a GSM radio technology.
[0038] The core network 106 may also serve as a gateway for the
WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet
110, and/or other networks 112. The PSTN 108 may include
circuit-switched telephone networks that provide plain old
telephone service (POTS). The Internet 110 may include a global
system of interconnected computer networks and devices that use
common communication protocols, such as the transmission control
protocol (TCP), user datagram protocol (UDP) and the internet
protocol (IP) in the TCP/IP internet protocol suite. The networks
112 may include wired or wireless communications networks owned
and/or operated by other service providers. For example, the
networks 112 may include another core network connected to one or
more RANs, which may employ the same RAT as the RAN 104 or a
different RAT.
[0039] Some or all of the WTRUs 102a, 102b, 102c, 102d in the
communications system 100 may include multi-mode capabilities
(i.e., the WTRUs 102a, 102b, 102c, 102d may include multiple
transceivers for communicating with different wireless networks
over different wireless links). For example, the WTRU 102c shown in
FIG. 1B may be configured to communicate with the base station
114a, which may employ a cellular-based radio technology, and with
the base station 114b, which may employ an IEEE 802 radio
technology.
[0040] FIG. 10 is a system diagram of the RAN 104 and the core
network 106 according to an embodiment. As noted above, the RAN 104
may employ an E-UTRA radio technology to communicate with the WTRUs
102a, 102b, 102c over the air interface 116. The RAN 104 may also
be in communication with the core network 106.
[0041] The RAN 104 may include eNode-Bs 140a, 140b, 140c, though it
will be appreciated that the RAN 104 may include any number of
eNode-Bs while remaining consistent with an embodiment. The
eNode-Bs 140a, 140b, 140c may each include one or more transceivers
for communicating with the WTRUs 102a, 102b, 102c over the air
interface 116. In one embodiment, the eNode-Bs 140a, 140b, 140c may
implement MIMO technology. Thus, the eNode-B 140a, for example, may
use multiple antennas to transmit wireless signals to, and receive
wireless signals from, the WTRU 102a.
[0042] Each of the eNode-Bs 140a, 140b, 140c may be associated with
a particular cell (not shown) and may be configured to handle radio
resource management decisions, handover decisions, scheduling of
users in the uplink and/or downlink, and the like. As shown in FIG.
10, the eNode-Bs 140a, 140b, 140c may communicate with one another
over an X2 interface.
[0043] The core network 106 shown in FIG. 10 may include a mobility
management entity gateway (MME) 142, a serving gateway 144, and a
packet data network (PDN) gateway 146. While each of the foregoing
elements are depicted as part of the core network 106, it will be
appreciated that any one of these elements may be owned and/or
operated by an entity other than the core network operator.
[0044] The MME 142 may be connected to each of the eNode-Bs 140a,
140b, 140c in the RAN 104 via an S1 interface and may serve as a
control node. For example, the MME 142 may be responsible for
authenticating users of the WTRUs 102a, 102b, 102c, bearer
activation/deactivation, selecting a particular serving gateway
during an initial attach of the WTRUs 102a, 102b, 102c, and the
like. The MME 142 may also provide a control plane function for
switching between the RAN 104 and other RANs (not shown) that
employ other radio technologies, such as GSM or WCDMA.
[0045] The serving gateway 144 may be connected to each of the
eNode Bs 140a, 140b, 140c in the RAN 104 via the S1 interface. The
serving gateway 144 may generally route and forward user data
packets to/from the WTRUs 102a, 102b, 102c. The serving gateway 144
may also perform other functions, such as anchoring user planes
during inter-eNode B handovers, triggering paging when downlink
data is available for the WTRUs 102a, 102b, 102c, managing and
storing contexts of the WTRUs 102a, 102b, 102c, and the like.
[0046] The serving gateway 144 may also be connected to the PDN
gateway 146, which may provide the WTRUs 102a, 102b, 102c with
access to packet-switched networks, such as the Internet 110, to
facilitate communications between the WTRUs 102a, 102b, 102c and
IP-enabled devices.
[0047] The core network 106 may facilitate communications with
other networks. For example, the core network 106 may provide the
WTRUs 102a, 102b, 102c with access to circuit-switched networks,
such as the PSTN 108, to facilitate communications between the
WTRUs 102a, 102b, 102c and traditional land-line communications
devices. For example, the core network 106 may include, or may
communicate with, an IP gateway (e.g., an IP multimedia subsystem
(IMS) server) that serves as an interface between the core network
106 and the PSTN 108. In addition, the core network 106 may provide
the WTRUs 102a, 102b, 102c with access to the networks 112, which
may include other wired or wireless networks that are owned and/or
operated by other service providers.
[0048] Other network 112 may further be connected to an IEEE 802.11
based wireless local area network (WLAN) 160. The WLAN 160 may
include an access router 165. The access router may contain gateway
functionality. The access router 165 may be in communication with a
plurality of access points (APs) 170a, 170b. The communication
between access router 165 and APs 170a, 170b may be via wired
Ethernet (IEEE 802.3 standards), or any type of wireless
communication protocol. AP 170a is in wireless communication over
an air interface with WTRU 102d.
[0049] In either of the systems shown in FIG. 1B and 10, an
operator may choose to use both licensed and unlicensed spectrum
for the reasons discussed herein. There may be constraints that are
imposed on using unlicensed spectrum bands such as sharing the
spectrum with multiple WTRUs without a central controller by
employing channel sensing schemes. Operation or use of a cell,
transmission-reception point (TRP), or carrier in an unlicensed
band may be stand-alone or assisted by operation or use of a cell,
TRP, or carrier in a licensed band. Such an assisted deployment
scenario may be referred to herein as licensed assisted access
(LAA). For LAA, the licensed cell, TRP, or carrier may be the
primary or anchor cell, TRP, or carrier.
[0050] When considering a cellular system operation in unlicensed
spectrum, coexistence of the cellular system with other unlicensed
technologies such as Wi-Fi, as well as other cellular operators,
may need to be addressed in order to, for example, attempt to
minimize interference and provide for fairness among the users of
the spectrum. Mechanisms such as Listen-Before-Talk (LBT) or Clear
Channel Assessment (CCA) may be used. With LBT and CCA, a system
node such as an Access Point (AP), eNodeB (eNB), gNodeB (gNB), TRP,
user equipment (UE), WTRU, and the like, may listen to a channel
(e.g., a frequency band with a certain center frequency and
bandwidth) to determine if there may be another WTRU using the
channel before transmitting on the channel or a portion of the
channel. Listening and/or determining the usage of another WTRU may
include or be based on measurements that may include energy
detection.
[0051] LBT, CCA, and LBT/CCA may be used interchangeably herein. A
channel may be determined to be busy, occupied, or in use when a
measurement (e.g., of energy) is at or above a threshold. A channel
may be determined to be idle, free, clear, or unused when a
measurement (e.g., of energy) is at or below a threshold.
[0052] Clear, free, idle, available, not occupied, and not busy may
be used interchangeably. Not clear, not free, not idle,
unavailable, occupied, and busy may be used interchangeably.
Channel, frequency channel, and operating channel may be used
interchangeably. A CCA failure may mean a channel was found to be
busy. A CCA pass may mean that a channel was found to be clear.
[0053] In an example, a transmitter on a channel, such as a WTRU
with a potential UL transmission and/or an eNB with a potential DL
transmission, may evaluate and/or monitor (i.e., receive) the
channel to measure and/or determine signal presence or interference
on the channel prior to transmission in order to determine whether
the channel may be in use (e.g., busy and/or occupied) by another,
such as another system, WTRU, or signal. The transmitter may, for
example, compare the received signal and/or interference from the
channel to some criteria, such as one or more threshold levels, and
may determine based on the comparison whether the channel may be
free as part of a LBT/CCA step. If the transmitter determines the
channel is free, the transmitter may transmit on the channel. If
the transmitter determines the channel is not free, the transmitter
may not transmit on the channel and/or may defer the potential
transmission and/or discard the potential transmission. As
discussed herein, a transmitter may refer to any transmitting
device such as a WTRU, eNB, or the like). Similarly, a receiver may
refer to any receiving device, such as a WTRU, eNB, or the like).
In one example, a transmitter may be a WTRU (e.g., for UL
transmission) and/or an eNB (e.g., for DL transmission). In another
example, a receiver may be a WTRU (e.g., for DL reception) and/or
an eNB (e.g., for UL reception).
[0054] Frame Based Equipment (FBE) may refer to equipment for which
transmit/receive timing may be fixed, and/or structured. Load Based
Equipment (LBE) may not perform LBT/CCA according to a certain
frame structure (e.g., at fixed or defined times). LBE may perform
LBT/CCA whenever it has data to transmit. As discussed herein, FBE
may be any node or device such as a WTRU, UE, eNB, gNB, TRP, STA,
or AP, that may transmit and/or receive on a licensed or unlicensed
channel.
[0055] For channel evaluation, before performing a transmission or
a burst of transmissions on an operating channel, equipment may
perform a LBT/CCA check that detects energy on the channel as
discussed herein. An LBT/CCA time period for channel evaluation may
be a fixed or minimum amount of time. Channel Occupancy Time (COT)
may be the total time during which the transmitter may transmit on
the given channel without re-evaluating the availability of that
channel. A maximum COT (MCOT) value may be configured by the
system, and/or as dictated by the relevant wireless standard or
regulation. The MCOT for some transmitter may be set by the
manufacturer of the device but may be less than a MCOT value of the
system. Example values for MCOT may be 4 ms or 10 ms.
[0056] Idle Period may be the time (e.g., a consecutive period of
time) during which the equipment may not transmit on a channel. The
Idle Period may have a minimum requirement with respect to the COT,
such as 5% of the COT that may be used by a device, for example for
the current Fixed Frame Period.
[0057] If a transmitter determines that during or as a result of
LBT/CCA an operating channel or channels is clear, it may transmit
on the clear channel or channels (e.g., immediately). If the
transmitter determines during or as a result of LBT/CCA an
operating channel is occupied, it may not transmit in that channel
until it performs a subsequent LBT/CCA that determines the channel
to be clear. If the transmitter determines that during or as a
result of LBT/CCA an operating channel is occupied, it may not
transmit on that channel during the next Fixed Frame Period. An
LBT/CCA may be performed subsequent to determining a channel was
not clear and may involve a wait or back-off time before checking
for a clear channel.
[0058] In some scenarios, such as for 3GPP LAA, a WTRU may perform
CCA to determine whether a channel is free. If the WTRU determines
that the channel is not free, the WTRU may then add a back-off or
wait time, such as an additional contention window amount of time.
Once the WTRU determines the channel is free, the WTRU may check
again before actually transmitting (i.e., where the actual
transmission may not begin right after the channel is determined to
be free). For example, if the WTRU is not within a check-window
(e.g., 25 us) prior to actual transmission, the WTRU may perform
CCA for at least a check-window amount of time prior to actual
transmission, where the WTRU may only transmit if the channel is
determined to be free for at least part of the check-window amount
of time.
[0059] Any reference to a CCA may be a full CCA or a short CCA. A
full CCA may include adding one or more back-off times when a
channel is determined to be busy. A short CCA may be a quick check
(e.g., energy detection check) in a check-window prior to the start
of transmission or intended/planned transmission. For example, when
a WTRU performs CCA for a first subframe (SF) or symbol, the WTRU
may perform a full CCA to determine whether the channel is free.
The WTRU may perform a short CCA prior to the actual transmission
to re-check that the channel is still free, for example if there is
a gap between the end of the full CCA and the start of the actual
transmission.
[0060] In some scenarios, such as LTE LAA UL, a WTRU may perform
CCA for a transmission beginning on the starting boundary of a time
period or beginning on a boundary of a time unit that may be within
a time period.
[0061] A subframe is used herein as a non-limiting example of a
time period, time unit, and/or time resource. Other examples of a
time period include a set of subframes, a frame, a set of frames, a
slot, a mini-slot, a set of slots or mini-slots, a TTI, a short
TTI, a multi-symbol TTI, symbol, a set of TTIs, a set of symbols, a
sync burst, a sync block, a set of sync bursts or sync blocks, and
the like. A symbol is used herein as a non-limiting example of a
time unit that may be within a time period. A time period may
comprise one or more time units. Other examples of a time unit may
include a slot, a mini-slot, a TTI, a short TTI, a multi-symbol
TTI, a set of symbols, a sync burst, a sync block, and the like. In
some instances, time unit, and time period may be used
interchangeably. In some instances, a time unit may be a subframe.
In some instances, a time resource may be, or may be used to
represent, one or more time periods and/or one or more time
units.
[0062] In an example, a WTRU may perform a full CCA for a
transmission beginning on a subframe boundary or for a transmission
beginning on an indicated symbol boundary within a subframe. The
WTRU may receive a grant for one subframe (e.g., a full or partial
subframe) or for a set of consecutive subframes. The WTRU may
perform a short CCA before transmitting on a granted subframe. For
a set of granted subframes, if the WTRU determines that the CCA
fails (e.g., the channel is busy or not idle), the WTRU may perform
a full/short CCA for the next, or later, granted subframe. When the
WTRU determines the channel to be free for a subframe in a set of
granted subframes, the WTRU may transmit on that subframe and the
remaining subframes in the granted set. Transmission may be
performed without performing a CCA for the subsequent subframes,
for example when a transmission is continuous. If there is a break
in the transmission, the WTRU may perform another short CCA for
transmission on a subframe in the set after the break.
[0063] In an embodiment channel sharing may be implemented using
time durations (e.g., windows or gaps) where a device (e.g., WTRU)
may not use a channel. The time durations for when a channel may be
used and/or not used may be preconfigured. A coexistence gap may be
used to represent a time duration when a channel may not be used,
for example based on a configuration.
[0064] A device may not use a channel for transmission and/or
reception during a coexistence gap. The device may consider the
channel as busy or unavailable during a coexistence gap. The device
may consider the channel to be free, usable, or available at a time
other than the time of a coexistence gap, for example when one or
more coexistence gaps are configured (e.g., determined based on a
configuration) and/or when a CCA is not used to determine channel
availability.
[0065] In an embodiment, a WTRU may employ coverage enhancement
(CE) techniques. For instance, a WTRU may use repetition to improve
the performance or coverage of a transmission or reception.
Repetitions of a transmission may be combined (e.g., soft combined)
at a receiver to improve the performance or coverage of a
transmission or reception. In a CE example, a transmitter may
repeat a transmission X times (i.e., X time periods or time units)
and a receiver may combine up to X of the transmissions in order to
successfully receive the transmission, where a successful reception
may be determined based on a CRC check. There may be one or more CE
levels supported in a cell and/or by an eNB. A WTRU may determine
and/or operate using a CE level. A CE level may use, may correspond
to, and/or may be configured with a number of repetitions. The
number of repetitions that may be used for a CE level may be
different for different WTRUs and/or different purposes (e.g.,
different signals or channels). A WTRU may transmit and/or receive
according to a CE level and/or a number of repetitions that may be
configured (e.g., configured for a CE level). A higher CE level
(e.g., a CE level with more CE) may use more repetitions.
[0066] In some scenarios, devices (e.g., WTRUs) may operate or may
be limited to operate within in a bandwidth (BW) that may be less
than the operating BW (e.g., system bandwidth, a carrier bandwidth
in a system) of a cell or node where the cell or node may be at
least one of: a) a cell or node on which the WTRU is camped; b) a
cell or node where the WTRU is connected or communicating; and/or
c) a cell or node that is a serving cell or node of the WTRU. Such
a WTRU may be considered a bandwidth (BW) limited or narrowband
(NB) WTRU. The bandwidth limited or NB WTRU may have a limited
capability of transmitting and/or receiving signal in a limited
bandwidth or a narrowband at a time. BW limited and NB may be used
interchangeably herein.
[0067] The BW limitation of a WTRU may be an RF BW limitation. The
BW limitation of a WTRU may be a value such as 200 kHz or 1
Physical Resource Block (PRB), 1.4 MHz or 6 PRB, or 3 MHz or 15
PRBs.
[0068] A BW limited or NB WTRU that may be limited to operation in
a NB such as 1 or 6 PRBs may be limited per time duration, time
period, or time unit. For example a BW limited WTRU may transmit
and/or receive in one NB at or during a first time unit or time
period and another NB at or during a second time unit or time
period. There may or may need to be a gap in time between the first
and second time units or time periods, for example to enable the
WTRU to tune to the second NB.
[0069] A NB WTRU may transmit (or receive) a portion of its
transmission (or a transmission from another node) in each of
multiple time units or time periods, for example to compensate for
its BW limitation. For example, a WTRU that may be limited to one
PRB in a time unit or time period may transmit (or receive) a 6 PRB
transmission as 1 PRB in each of 6 time units or time periods.
[0070] A WTRU that is not BW limited may transmit or receive (e.g.,
a transmission that may be or may include a signal, a channel, a
transport block, etc.) using or over a first time unit (or time
period) such as a subframe. A WTRU that is BW limited may transmit
or receive using a second time unit (or time period) that may be a
multiple of the first time unit.
[0071] As discussed previously, the amount of time that a device
may occupy (e.g., transmit on) an unlicensed channel may be
limited, for example, by an configured value, such as the MOOT. The
MOOT may be based on at least one of fairness, a standard, or a
regulation.
[0072] For some applications, for example narrowband, bandwidth
limited, and/or CE applications, a transmission (e.g., of a control
channel, data channel, or transport block) may need or use a set of
time units and/or time periods to complete the transmission. The
set of time units and/or time periods may exceed a limitation such
as a MOOT. The transmitter may or may need to release the channel
before the transmission is complete. For example a CE transmission
may use 100 subframes and MOOT may be 10 ms (e.g., 10
subframes).
[0073] Systems, methods, and devices may be needed to enable a
transmitter to release a channel at least once during a
transmission and later complete the transmission, such that a
receiver may be able to receive (e.g., successfully receive) the
full transmission. To address this need, one or more of the
following may be employed: transmissions may be based on available
resources when a channel is free; transmissions in N of M allocated
resources for both a single allocation and sets of allocations;
transmissions may be split into multiple bursts; and/or an
indicator may be included (and used) with each burst to enable the
receiver to assemble or combine the bursts. For example, a WTRU may
transmit a transmission of at least one channel (e.g., data or
control channel) and/or transport block using a set of resources
(e.g., in time and/or frequency) when the transmission fits in a
remaining subset of the set of resources when the channel (e.g.,
frequency channel) is determined to be usable or available (e.g.,
when CCA is determined to pass).
[0074] As discussed herein, a transmission may be or may include at
least one channel, signal, transport block, codeblock group, or
codeblock, wherein a transport block may correspond to one or more
codeblocks or codeblock groups. A transmission may be or may
include one or more repetitions (e.g., a set of repetitions) of a
channel, signal, or transport block that may be combined (e.g.,
soft combined) to receive and/or decode (e.g., to successfully
receive and/or decode) the channel or transport block.
[0075] A burst may be or may include at least part of a
transmission that may be or may need to be transmitted and/or
received, for example in a set of resources. A burst may be or may
include at least part of a channel (e.g., a data channel, a control
channel, a random access channel, and/or a broadcast channel), a
signal, a codeblock, a codeblock group, or a transport block that
may be or may need to be transmitted and/or received, for example
in a set of resources. A burst may be or may include a set of
repetitions or a subset of a set of repetitions of a channel, a
signal, a codeblock, a codeblock group, or a transport block that
may be transmitted and/or received, for example in a set of
resources.
[0076] FIG. 2A illustrates an example process for a transmission
based on available/allocated resources. In this example, the
transmission may be based on available resources when a channel is
free. At 202, a transmitter (e.g., WTRU) may receive a grant,
allocation, or configuration for a transmission (e.g., an UL
transmission). The grant, allocation or configuration may include a
set of transmission parameters and/or a set of resources (e.g.,
time and/or frequency resources such as subframes or PRBs). For
example, a set of M time resources (e.g., M SFs) may be granted,
allocated, and/or configured. The M time resources may be
contiguous or non-contiguous time resources. The term "allocated"
may be used to represent granted and/or configured as discussed
herein.
[0077] At 204, the transmitter may perform CCA (e.g., full CCA) and
determine the start time for a first time resource (e.g., a first
subframe), where the first time resource may be the first of the M
allocated resources. The start time for a transmission may be
configured or indicated with respect to an allocated time resource.
The start time may, for example, be the start of the time resource
or the start of a time unit such as the n.sup.th symbol within the
time resource. At 205, the transmitter may perform CCA (e.g., short
CCA) for the first resource (e.g., the first of the M subframes)
immediately before the time when the transmission starts (i.e., the
start time).
[0078] At 206Y, if it determined that the channel is clear for
transmission in the time resource, the WTRU may begin transmitting
in the time resource at 209. At 206N, if the channel is not clear
for transmission, the transmitter may not transmit in that time
resource. At 207 the transmitter may determine when the next time
resource, within the M time resources, a transmission may occur
(i.e., checking if the channel is clear by performing CCA) and
deferring the transmission to that time.
[0079] At 208, the transmitter may determine if the transmission
fits within the remaining time resources of the M resource
allocation (e.g., beginning with transmission in the next
resource). At 208N, if the transmitter determines the transmission
does not fit, the transmitter may not use the remainder of the
allocation and my end the process at 213. At 208Y, if the
transmitter determines the transmission fits, the transmitter may
transmit in the next resource, for example after determining the
channel to be available based on performing CCA at 205.
[0080] FIG. 2B illustrates a several examples and the example
process of FIG. 2A, where there is transmission based on
available/allocated resources. As discussed above, the transmitter
may receive a grant/allocation of M resources 222 (e.g., six
subframes numbered 4-9) and the transmission 230 (e.g., of a
channel or transmission block (TB)) may be K resources in length
224 (e.g., two subframes). There may be a total of twelve possible
subframes 231 numbered 1-12. The subframes 231 with dotted lines
may indicate that they are outside of the grant M 222, and the
subframes 231 with solid lines are within the grant M 222.
[0081] In one example 230A, the transmitter may determine that the
channel is available for transmission at a certain point in time
226A (e.g., start time after subframe 7). The transmitter may then
determine that the remaining resources, that is the number of
resources remaining between the start time 226A and the end of the
grant M 222, in the grant is larger than or equal to the resources
that the transmitter may need for the transmission 224A. In this
example, assuming a K long transmission (e.g., two subframes), the
transmission 224A fits into the remaining time grant 222 as shown
by the blocks with diagonal lines (i.e., subframes 8 and 9), and
therefore the transmitter will be able to send the transmission
224A.
[0082] In one example 230B, the transmitter may perform CCA (e.g.,
full CCA) and determine that the channel may be available for
transmission at a certain point in time at a particular subframe
226B. The transmitter may then determine that the remaining
resources (e.g., the number of remaining subframes) in the grant
(e.g., one subframe) is smaller than the transmission 224B and the
transmitter may not transmit. Specifically, since the next
transmission opportunity is at the end of subframe 8 and the
transmission 224B requires two subframes, it would not fit within
the grant M 222 which only has one subframe remaining between the
end of the grant M 222 and the next available transmission 226B. As
discussed herein, allocation of M resources may be semi-statically
configured (e.g., via semi-persistent scheduling, SPS), or
dynamically configured (e.g., via a control channel and/or
DCI).
[0083] FIG. 3A illustrates an example process of a time limited
transmission for a set of allocated resources. In some case, a
transmission may have one or more limitations, such as when a
transmitter receives an allocation for a set of M resources and may
only use N (e.g., at most N) of the M resources for transmission,
where the actual values of M and N may be preconfigured. The M
resources may be contiguous in time and the transmitter may use
(e.g., transit in) up to N contiguous resources in time. In some
instances, N may be or may correspond to a MOOT.
[0084] As discussed herein, M and/or N may be configured
semi-statically (e.g., by higher layer signaling) or dynamically
(e.g., by a control channel and/or DCI). Also, in some instances, M
and/or N may be included in or with an UL grant or a triggering
DCI.
[0085] In the example process shown in FIG. 3A, at 301 a
transmitter (e.g., WTRU) may receive a configuration of a maximum
transmission length N, where N may be a number of resources (e.g.,
consecutive or contiguous resources) that the transmitter may use
for transmission. At 302, the transmitter may receive an allocation
(e.g., an UL allocation or grant) for a set of M resources (e.g., M
subframes). In this example, N may be less than or equal to M, and
N may be set to a MOOT to meet a MOOT requirement.
[0086] At 304 the transmitter may perform a CCA (e.g., full CCA)
determine the start time for a first time-resource (e.g., a first
subframe), where the first time resource may be the first of the M
granted resources. The start time for a transmission may be
configured or indicated with respect to an allocated time resource.
The start time may be the start of the time resource or a start of
a time unit such as the n.sup.th symbol within the time
resource.
[0087] At 305 the transmitter may perform CCA (e.g., short CCA)
immediately before the start of the first transmission time within
the set of M resources (e.g., subframes), and in doing so may
determine whether the channel is free and available.
[0088] If the transmitter determines the channel is available at
306Y, the transmitter may transmit in one or more resources within
the allocated M resources at 309. The transmitter may transmit in
up to N contiguous resources and the number of contiguous resources
that the transmitter may transmit may be determined (e.g., by the
transmitter) based on at least one of: M; N; the remaining time
resources in the allocation (e.g., when the transmitter determines
the channel to be free); the number of resources the transmitter
may need or use for its transmission (e.g., of at least one channel
or transport block); and/or the amount of data the transmitter must
transmit. For example, the transmitter may transmit in up to N of
the M resources after determining that there are enough remaining
resources for the transmitter's transmission (e.g., of at least one
channel or transport block). In some instances, between consecutive
(e.g., contiguous) transmissions, the transmitter may not recheck
channel availability; also, when there is a break in transmission,
the transmitter may recheck channel availability.
[0089] If the transmitter determines that the channel is busy at
306N, the transmitter may not transmit at the start of the first
transmission time. At 307 the transmitter may determine the next
transmission time (e.g., within the allocation) if one exists. The
transmitter may determine whether the transmitters transmission
fits in the remaining transmission time (e.g., that begins with the
next transmission time). When the transmitter determines that the
transmission may not fit in the remaining time 308N, the
transmitter may not use the remainder of the allocation 313. When
the transmitter determines that the transmission may fit in the
remainder of the allocation 308Y, the transmitter may try again at
the next transmission time and the transmitter may perform CCA at
305 to determine if the channel may be free for transmission before
the start of the next transmission time (e.g., within the
allocation).
[0090] FIG. 3B illustrates a visual explanation along with several
examples of the process of FIG. 3A, where there is a time limited
transmission for a set of allocated resources. At 330, a
transmitter may receive an allocation of M resources 322 (e.g., six
subframes of a total twelve subframes 331) and the transmitter
transmission (e.g., of a channel or transmission block) may use K
resources 324 shown by blocks with diagonal lines (e.g., two
subframes). The transmitter may receive a configured maximum
transmission length of N 328 (e.g., four subframes) resources. When
a channel is busy it may be indicated by a box with dots 321. The
subframe 331 boxes with dotted lines may indicate that they are
outside of the grant M 322, and any subframe boxes 331 outlined
with solid lines may be within the grant M 322
[0091] In the examples of 330A and 330B, when the transmitter
determines the channel may be available for transmission, the
remaining resources in the grant M 322 (e.g., the number of
subframes) in the allocation (e.g., five subframes for 330A and
four subframes for 330B) may be larger than (or equal to) the
maximum transmission length, N. Specifically for 330A, based on a
CCA the transmitter may determine that the channel is busy at
subframe 4, therefore the start time for the transmission may be
326A and the transmission N 324A should fit within the grant M 322.
Similarly for 330B, the start transmission time may be determined
to be 326B after the channel is not busy, and the transmission of N
324B should fit within the grant M 322. The transmitter may
transmit in up to N 328 (e.g., four subframes) resources, but may
transmit less in some instances. For example, the transmitter may
transmit two transport blocks of length K 324 in four resources
(i.e., subframes), so the transmitter may transmit two transport
blocks. In another example, N may be three and only one
transmission block may fit in three resources, therefore only one
transmission block would be transmitted by the transmitter.
[0092] When the transmitter has enough data for N resources (e.g.,
subframes), the transmitter may transmit multiple times (e.g.,
multiple back-to-back transport blocks).
[0093] In the examples of 330C and 330D, when the transmitter
determines the channel may be available for transmission, the
number of remaining resources in the grant M 322 (e.g., subframes)
may be smaller than the configured maximum N 328. The transmitter
may determine whether it may transmit once or multiple times (e.g.,
multiple transport blocks). In both 330C and 330D the number of
remaining subframes in the allocation is not large enough to fit
two transmissions (e.g. two transport blocks) by the transmitter.
Specifically for 330C, the transmitter may determine that the
channel is busy up until 326C, at which point the transmission N
324C may only have room for one transport block and subframe 9 may
not be used. Similarly for 330D, the transmission may begin at 326D
which may only leave room for one transport block for the
transmission 324D. In other examples, the transport block length K
may be a different length, such as one, in which case for 330D for
example, you could fit three transport blocks after the determined
start time 326D.
[0094] In an embodiment, an allocation of resources (i.e., a set of
M resources) may be referred to as a Transmit Opportunity Window
(TOW) that may be used by a transmitter (e.g., a WTRU or eNB) to
send a transmission to a receiver (e.g., eNB or WTRU). A
transmitter (e.g., a WTRU) may complete a transmission in TOW when
it transmits at least one channel (e.g., data or control channel)
or TB in the remaining resources of an allocation of the TOW, for
example when a WTRU determines the channel (e.g., the frequency
channel) may be free. The allocation of multiple TOWs may be valid
until cancelled, for example like semi-persistent scheduling (SPS),
or it may be configured with a duration or a number of TOWs (e.g.,
W sets).
[0095] One or more parameters of one or more set(s) of resource
allocations or TOW(s) may be signaled via higher layer signaling
(e.g., RRC signaling) and/or via a control channel (e.g., in a
DCI). The parameters may be preconfigured, periodic, scheduled, or
triggered aperiodically. A device (e.g., eNB) may configure or
indicate the parameters to a transmitter, where the parameters may
include at least one of: number of time resources (e.g., subframes)
per set/TOW (M); maximum transmission length (N) within a set/TOW;
number of sets/TOWs (W), or total duration of the multi-set/TOW
allocation; timing of the allocation (e.g., frame, subframe, slot,
etc. of a set/TOW of the multi-set allocation); time
duration/period between consecutive sets/TOWs (e.g. measured in
frames, subframes, slots, etc.); periodicity of the sets/TOWs; an
offset to a next set/TOW (e.g. in resources or subframes); an
indication of a start and/or first set/TOW (e.g. a first resource
or subframe); an indication of an end and/or last set of
resources/TOW (e.g. a last resource or subframe); a duration (e.g.
M in resources or subframes); and/or an indication of how the
allocation may be activated and/or deactivated.
[0096] A transmitter may provide an indication to another entity
(e.g., a WTRU to an eNB or gNB) that the transmitter may no longer
need the allocation and/or that the allocation may be released or
deactivated. For example, a WTRU may transmit at least one of the
following (e.g., in a last transmission) to provide the indication
for ending the allocation: a buffer status report indicating zero
size; an indication in a control channel (e.g., UL control
channel); a reference signal (e.g., a configured reference signal);
a sequence (e.g., a unique or configured sequence); and/or a PRACH
resource reserved. The transmitter may provide the indication when
it has no more data to send. The indication may be used as an end
marker for a set/TOW of one or more transmissions. The indication
may be provided and/or used to indicate and/or determine the last
burst of a split burst transmission. A transmitter may provide the
indication in or with a transmission (e.g., an UL transmission or a
DL transmission) and a receiver may receive the indication.
[0097] In some circumstances a device (e.g., eNB) may allocate or
schedule multiple TOWs that may be non-contiguous, for example when
a transmission (e.g., to or by a WTRU) may exceed a time limit
(e.g., N or a MOOT restriction). The device may for example
allocate W TOWs, where the (e.g., each) TOW comprises M time
resources and a transmitter may only transmit using up to N of the
M time resources of the TOW. Further, a device (e.g, eNB) may
indicate multiple start times, for example for aperiodic
scheduling. For TOWs with different durations, the device may
indicate a duration for one or more (e.g., each) TOW.
[0098] FIG. 4A illustrates an example process of a transmission
split into a burst(s). As discussed herein, the total message
(e.g., data or control) that a transmitter may wish to transmit may
be referred to as a transmission. In some circumstances, the total
transmission may not fit into a set (e.g., TOW) of allocation of
resources (e.g., the transmission may use or may need to use more
than N resources or more than the MOOT), and may need to be broken
up into one or more bursts. The bursts may be organized into sets
of one or more bursts where the burst size and/or number of bursts
transmitted for a given TOW will only be transmitted in N or fewer
resources. In one example, the transmission may be a NB (e.g.
NB-IoT), bandwidth limited (BL) or CE transmission.
[0099] At 401, a transmitter (e.g., an eNB or a WTRU) may receive a
configuration of a maximum transmit length of N resources (e.g.,
time resources). At 402 the transmitter may be allocated one more
set of M resources for one or more transmissions, where only N of M
resources may be used.
[0100] At 403, the transmission may be split (e.g., divided or
segmented) into a set of B bursts (e.g., by a WTRU, eNB, or a
transmitting device), when the transmission may need or may use K
resources (e.g., in time) where K may be less than N, otherwise
each burst may use (e.g., may be transmitted in) N resources (e.g.,
no more than N resources), where N may be preconfigured. The bursts
in the set of bursts may be the same size or different sizes.
Generally, the transmitter may determine the number/size of bursts
for a transmission based on at least one of: a) the resource (e.g.,
the first resource) within the set of resources where the
transmitter determines the channel to be free; b) the remaining
time in the set of resources, for example when the transmitter
determines the channel to be free; c) the number of bursts still to
be transmitted which may be B or less; and/or d) N. In some
instances, the transmission may be adapted such that the bursts may
be the same size (e.g., padding or rate-matching may be used). For
example, the transmitter may transmit up to the number of bursts
that may fit in the time left or remaining (e.g., when the channel
is determined to be free or beginning with the transmission
opportunity for which the channel is determined to be free), while
not exceeding MOOT or N (e.g., the max allowed number of contiguous
time resources (e.g. subframes) that may be used for
transmission).
[0101] At 404 the transmitter may perform a CCA (e.g., full CCA)
and determine the start time for the transmission in a first
resource of a TOW. At 405, the transmitter may determine channel
availability using CCA (e.g., short CCA) immediately before the
transmission of a subset of the B bursts, (e.g., B.sub.sub bursts),
in up to N of the M resources.
[0102] As discussed herein, the allocation of the one or more sets
of M resources that may be used for the transmission may comprise a
finite number of TOWs (e.g., W) or may be allocated until cancelled
or deactivated. In some cases, the allocation may be for a specific
transmission, and the value of M may be the same or different for
different TOWs. Also, the value of N may be the same or different
for different TOWs. For example, the value of N may change (e.g.,
may be configured or reconfigured) depending on the set of
resources or for different TOWs.
[0103] At 405, if the channel is clear at 406Y based on a CCA (e.g,
short CCA), then at 409 the transmitter may transmit one or more
bursts (e.g., based on what fits) in the lesser of the remaining
resources or the N resources in the set of allocated resources M of
the TOW. For each burst or set of bursts a BI may be included. At
410N, if there are no more bursts to transmit from the original
bursts B, then the transmission process may be over 413. At 410Y,
if there are more bursts to transmit from the original bursts B,
then the transmitter determines if there are more TOWs available at
411. If there are more TOWs available 411Y, then the next
transmission time is determined 412, and the process cycles back to
CCA check before transmission 405. If there are not more TOWs
available 411N, then the transmission process may be over 413.
[0104] At 406N, if the channel is not clear for transmission, then
the next transmission time must be determined 407. The transmitter
may then determine if the burst will fit in the remaining time 408
of the given TOW (i.e. set of available resources). If the burst
does not fit 408N, then the transmitter determines whether more
TOWs are available 411, as discussed herein. If the burst does fit
in the remaining time 408Y, then the process cycles back to perform
a CCA check before transmission 405.
[0105] FIG. 4B illustrates additional examples and the example
process of FIG. 4A concerning a transmission using a split burst.
In the example as shown in FIG. 4B, the resources may be subframes,
the grant M resources 422 may be equal to six subframes, all sets
of granted resources (i.e., TOWs) may be the same, the maximum
transmit length N 428 may be equal to four subframes, a burst may
use one subframe, and a transmission opportunity may begin on a
subframe boundary.
[0106] In the example of 430A, a transmitter may attempt to
transmit a transmission, where the number of bursts (B) may be
seven and the transmitter may only transmit four bursts (N =4) at
most at a given time. The transmitter may determine that the
channel is available after subframe 1 (e.g. at the subframe
boundary) of TOW 431A. The transmitter may transmit N, four bursts,
in the TOW 431A, since the transmitter must transmit seven bursts
total and four is the most that can be transmitted in a given TOW
or transmission opportunity N 428. Consequently, the transmitter
may not use the last subframe of TOW 431A. The transmitter may
transmit the remaining bursts (e.g., the remaining three bursts) in
the next TOW of the allocation, TOW 432A, if and/or when the
channel is available. In the second TOW 432A, there are no busy
subframes so the channel is available to transmit in the first
available opportunity and the transmitter may then transmit the
remaining three bursts of the seven total bursts. In a later TOW
433A, there is no need for any further transmissions since the
transmission of all of the bursts is complete.
[0107] In the example 430B, there may be eight bursts. In a first
TOW 431B, the transmitter may determine that the channel is busy
for the entire TOW 431B. In the second TOW 432B, the transmitter
may find the channel is available in the first transmission
opportunity (i.e., subframe 1 of TOW 432B). The transmitter may
transmit bursts for the maximum allowed length N 428 (e.g., four
subframes). The transmitter may transmit the remaining bursts in
the next available TOW (or a later TOW), if and/or when the channel
is available. In some later TOW 433B (i.e., the next TOW or some
later TOW), the channel may be available at the second transmission
opportunity (i.e., subframe 2) and the transmitter may transmit the
remaining four bursts of the total eight bursts that needed to be
transmitted.
[0108] In the example of 430C, there may be eight bursts. In the
first TOW 431C, the transmitter may determine that the channel is
busy until the fifth transmission opportunity (i.e., subframe 5)
and may transmit as many bursts that can fit in the remaining grant
M 422 of TOW 431C, which in this example is two bursts. In the
second TOW 432C the transmitter may determine that the channel is
free right away and may transmit in the first transmission
opportunity (i.e., subframe 1 of TOW 432C) the maximum transmit
length N 428, which in this example is four bursts. The transmitter
may transmit the remaining bursts in the next available TOW (or a
later TOW), if and/or when the channel is available. In some later
set 433C (i.e., the next set or some later set), the channel may be
available at the second transmission opportunity (i.e., subframe 2)
and the transmitter may transmit the remaining two bursts of the
total eight bursts that needed to be transmitted.
[0109] In one example, the transmitter may be a WTRU with
parameters configured by a base station and the WTRU may perform
CCA before the start of a TOW and/or may determine if a channel is
or will be available for transmission at the start of the TOW. If
the channel is determined to be available, the WTRU may transmit in
up to N resources (e.g., beginning with the start of the TOW). If
the channel is determined to be unavailable at the start of the
TOW, the WTRU may perform (i.e., continue to perform) CCA for
transmission at a later time. When the WTRU determines the channel
to be idle within the TOW and there are enough resources remaining
to support the WTRU's transmission, the WTRU may transmit its
transmission.
[0110] FIG. 5 illustrates an example transmission process using a
burst indicator (BI). A burst indicator and a burst ID may be used
interchangeably, and may be unique to each burst (e.g., a burst
counter). In one example, a different BI may be transmitted in or
with a first burst and a second burst of a split-burst
transmission. The BI that may be transmitted in or with a burst may
indicate which burst (e.g., which burst number) of a split burst
transmission or of a set bursts the burst may be.
[0111] A BI may be, may include, or comprise one or more (e.g., a
set) of a pattern, a signature, a signal (e.g. a reference signal
(RS)), or a sequence. The term signal and/or sequence may be used
to represent a signature, a signal, and/or a sequence. A signal may
be a reference signal (RS) such as a cell-specific RS (CRS), a
demodulation RS (DMRS), a channel state information RS (CSI-RS)
among others. A sequence may be a Zadoff-Chu sequence. A BI and/or
a signal/sequence (or a set or pattern of signals/sequences) that
may be used for a BI may be unique and/or may be or configured for
a WTRU, a purpose, a channel or set of channels, a burst, a set of
bursts, a transmission, a split-burst transmission, among others.
Configuration may be via higher layer signaling (e.g., RRC
signaling) and/or physical layer signaling.
[0112] For example a BI that may be transmitted in or with an UL
burst transmission, and may be indicated or identified in a DCI.
The DCI may be or may include an UL grant or allocation, for
example for the full transmission that may be a split-burst
transmission. The WTRU may transmit the indicated (e.g.,
identified) BI in at least one of the burst transmissions of the
full or split-burst transmission.
[0113] Alternatively, a BI may be transmitted in or with an DL
burst transmission, may be indicated or identified in a DCI. The
DCI may be or may include a DL grant or allocation, for example for
the full transmission that may be a split-burst transmission. The
WTRU may combine one or more bursts that the WTRU may receive that
may include or be associated with a transmission of the indicated
(e.g., identified) BI.
[0114] The one or more signals/sequences or a pattern of one or
more signals/sequences of a BI may be at least one of the
following: WTRU-specific (e.g., configured for a WTRU); burst or
split-burst specific (e.g., configured for and/or associated with a
burst or a split-burst transmission); cell-specific (e.g.,
configured for a cell); group-specific; channel specific (e.g.,
specific to one or more channels such as one or more common
channels); channel-type specific; and/or HARQ process or HARQ
process ID specific (e.g., configured for and/or associated with a
HARQ process or HARQ process ID).
[0115] In one example, a WTRU may transmit a BI configured for a
HARQ process (e.g., HARQ process ID) when the WTRU may transmit a
burst for the HARQ process. A WTRU may combine one or more bursts
that may be associated with a HARQ process based on reception of a
BI in or with the one or more burst that may indicate the bursts
are associated with the HARQ process.
[0116] The example shown in FIG. 5 may be similar to the process
explained regarding FIG. 4A and 4B, except the transmission
parameters may be different and the burst indicator/burst identity
may be demonstrated. An associated control signaling may be
transmitted for each burst and the associated control signaling may
include a BI. Initially, a transmitter (e.g., WTRU) may be
configured with (e.g., may receive a configuration for) one or more
parameters associated with the division/splitting of at least one
transmission or type of transmission into bursts. For a given
transmission, the transmitter (e.g., WTRU) may receive and process
configuration information ahead of time (e.g., determining number
of bursts for a given transmission). A transmitter may receive the
configuration, which may include at least one parameter, via upper
layer signaling (e.g. RRC signaling) and/or or physical layer
signaling (e.g., via a control channel and/or a DCI).
[0117] The configuration (e.g., the one or more parameters) may
include at least one of the following: maximum transmission
length/time resources within a set (N); codeblock size (e.g., when
a burst may be based on codeblocks); burst size (e.g., in time,
number of resources, number of codeblocks, or number of
repetitions); minimum burst size and/or maximum burst size; number
of bursts (B); whether to insert per burst CRC; scheduling
parameters (e.g., MCS, frequency resources, transmission power,
etc.) of a burst, a set of bursts, or a subset of bursts; number of
time resources (i.e., time units) a burst may be mapped to (e.g.
number of slots, mini-slots, OFDM/DFT-s-OFDM symbols, subframe and
the like); one or more parameters that may identify and/or
configure a signature, signal, scrambling code, sequence and/or
pattern that may be included in or with a burst transmission;
and/or one or more parameters that may identify and/or configure a
burst indicator (BI) that may be included in or with a burst
transmission.
[0118] For the one or more parameters that may identify and/or
configure a signature, signal, scrambling code, sequence and/or
pattern that may be included in or with a burst transmission, each
burst in the set of bursts may have a burst identity (e.g., burst
ID) and the burst ID may be used to scramble the bits in each
burst. For example, the coded bits of a burst may be scrambled with
its associated burst ID (e.g., the burst ID may be used to initiate
the scrambling code of the burst).
[0119] Referring to the example of FIG. 5, a transmitter may
transmit a transmission 530 using a set of resources, such as a
multi-subframe grant M 522. The transmission 530 may be broken up
in to bursts based on a received configuration, such as a burst
size of two subframes 525. The maximum transmit length N 528 may be
set to the MOOT and may be equal to four subframes. In this
example, the entire uplink transmission 530 may comprise eight
subframes and be broken up into four bursts. Each burst may have a
burst ID 539, such as 501, 502, 503, and 504, where each burst
contains two subframes.
[0120] For the first TOW 531, a start time may be determined by
performing a CCA (e.g., full CCA) where the transmitter determines
that the channel is not busy after subframe 4, at which point the
transmitter determines how many of the bursts may fit in the
remaining grant of resources 522 when the channel (e.g., frequency
channel) is determined to be usable or available (e.g., when CCA is
determined to pass). For example, in the first TOW 531 the first
burst with burst ID 501 may be transmitted in subframes 5 and 6,
and subframe 7 may not have a burst. The process may continue until
the entire UL transmission 530 is sent.
[0121] In the second TOW 532, the channel may be busy through
subframe 6, meaning that there would be not enough subframes left
in the grant M 522 to send any bursts. The process would continue
to the third TOW 533 where after subframe 1 the channel may be free
and even though three bursts may fit in the remaining grant M 522,
only the next two bursts, 502 and 503, may be transmitted since
there is an MOOT 528 of four subframes (i.e., two bursts). In the
next TOW 534, the channel may be free immediately and the last
burst, burst ID 504, may be sent leaving no more bursts to send in
the remaining SFs since the entire UL transmission 530 has been
sent.
[0122] In the example of FIG. 5, the burst ID may be used to
scramble the bits in each burst. Additionally, for the one or more
parameters that may identify and/or configure a signature, signal,
scrambling code, sequence and/or pattern that may be included in or
with a burst transmission, a DM-RS sequence/pattern for a burst may
be determined based on its associated burst ID. For example, a
burst may be transmitted with an associated DM-RS and the
associated DM-RS sequence/pattern may be determined based on the
burst ID. In such a case, at least one of following may apply: one
or more cyclic shifts of a base sequence (e.g., Zadoff-Chu
sequence, Golay sequence, m-sequence) may be used as DM-RS
sequences and a cyclic shift for a DM-RS may be determined based on
the burst ID; and/or one or more DM-RS patterns may be used based
on the interleaved frequency domain multiplexing (IFDM), and a
DM-RS pattern may be determined based on a frequency offset where a
frequency offset (e.g., a DM-RS pattern) for a DM-RS may be
determined based on the burst ID.
[0123] For one or more parameters that identify and/or configure a
burst indicator (BI) included in or with a burst transmission, a
CRC may be used or attached for each burst, and, a burst indicator
(BI) may be transmitted implicitly with a CRC scrambling. For
example, the CRC may be scrambled with an associated BI at a
transmitter, and a receiver may descramble the CRC with the
associated BI for CRC check.
[0124] Also for one or more parameters that may identify and/or
configure a burst indicator (BI) that may be included in or with a
burst transmission, a subset of resource elements (REs) in a burst
may be reserved (e.g., REs next to the DM-RS) and the BI may be
transmitted in the subset of REs.
[0125] In some cases, one or more bursts of a split burst
transmission may be the same. For example, a first burst of a
transmission that may be split into B bursts may be a replica of a
second burst of the transmission. Further, when bursts may be used
for carrying repetitions (e.g., CE repetitions) of a signal or
channel, one or more (e.g., all) bursts of a split burst
transmission may be the same (e.g., may comprise, include, or carry
the same bits which may be coded bits). One or more bursts may be
the same inclusive or exclusive of a BI that may be include in or
with the burst transmission. The repetition of a transmission may
include a repetitive transmission of the same information bits
while the redundancy version of the coded bit may be different in
each repetition. For example, a same information bits may be
channel coded and a different part of coded bits may be transmitted
based on repetition number.
[0126] In another example a first burst of a split burst
transmission may carry a subset of the bits or symbols of the
transmission and a second burst of the split burst transmission may
carry a different subset of the bits or symbols of the
transmission. For example, a transport block (e.g., that may use
multiple resources for transmission) may be partitioned into B
bursts, where each burst may carry a subset (e.g., a different
subset) of the bits or symbols of the transport block. Further, the
partitioning may be at the codeblock level; a burst may comprise,
include, or carry one or mode codeblocks of a transmission (e.g.,
of a transport block).
[0127] FIG. 6 illustrates an example of a process for receiving a
transmission using a bit indicator. At 601 a receiver may receive a
configuration for BI and/or determine a BI, or set of BIs, to use
for receiving a split burst transmission. At 602 the receiver may
monitor for a BI, or at least one BI in a set of BIs, in one or
more resources (e.g., subframes). The receiver may attempt to
receive one or more bursts of a split burst transmission. If a BI
is not received 603N and this is the last resource or set of
resources/TOW to monitor 606Y, then the process may be over 607. If
a BI is not received 603N and it is not the last resource or set of
resources/TOW to monitor 606N, the process may go back to
monitoring 602.
[0128] If a BI is received 603Y, then the receiver will receive,
store, and/or combine 604 the associated burst with one or more
other bursts of the split burst transmission. When a burst carries
a subset (e.g., of the bits) of a full transmission, the receiver
may combine (e.g., assemble or concatenate) the bursts to obtain,
receive and/or decode (e.g., successfully receive and/or decode)
the full transmission. When a burst carries a repetition (e.g., of
the bits) of a transmission, the receiver may combine (e.g., soft
combine) the bursts to receive and/or decode (e.g., successfully
receive and/o decode) the transmission. A BI may be provided (e.g.,
transmitted) and/or used (e.g., by a transmitter), for example to
enable a receiver to combine the bursts of a split burst
transmission. A receiver may use at least one BI to determine when
and/or how to combine one or more bursts of a split burst
transmission.
[0129] If the last burst or split-burst transmission was
successfully received 605Y, then the process may be over 607. If
the last burst or split-burst transmission was not successfully
received 605N, then the receiver determines whether this is the
last resource or set of resources/TOW to monitor.
[0130] Generally, a receiver may monitor a resource (e.g., each
resource) such as a subframe or slot for a BI. For example a WTRU
may monitor each resource that may be at least one of: a DL
resource; a resource configured for burst transmission and/or
reception; and/or a resource configured for the transmission and/or
reception of a specific burst transmission or a type of burst
transmission (e.g., a common or WTRU-specific transmission). When
the receiver receives a BI, the receiver may receive an associated
burst and/or combine an associated burst with a previously received
burst that may have been associated with the same BI.
[0131] The BI may be received in several possible ways, for
example: the BI may be included with (e.g., as part of) a burst
transmission (e.g., each burst transmission); the BI may precede
(e.g., may be transmitted and/or received before) a burst
transmission or a set of burst transmissions; the BI may follow
(e.g., may be transmitted and/or received after) a burst
transmission or a set of burst transmission; the BI may be
transmitted and/or received during a burst transmission; and/or the
BI (e.g., a BI transmission) may be (e.g., at least partially)
interleaved and/or overlapped with a burst transmission in time
and/or frequency.
[0132] In some cases, a receiver may successfully receive a BI in
or based on a single transmission of the BI without repetition
(e.g., in multiple bursts). The BI may enable a receiver to
determine or detect the presence of a burst, for example to combine
with one or more previously received bursts. A receiver may
determine a burst to be present (e.g., in a resource) based on
reception of a BI (e.g., in or with the resource). The receiver may
use a BI to combine (e.g., assemble or soft-combine) a received
burst with a previously received burst, (e.g., based on a received
BI). For example, when a transmission (e.g., of a channel or
transport block) may be repeated across multiple bursts.
[0133] Repeated bursts and/or BIs may be used and/or provided
(e.g., when CE is used). A BI may be used by a receiver to
determine that a transmission may be a burst of a split burst
transmission and/or a repetition of a transmission. The receiver
may combine or determine to combine a first burst or transmission
with a second burst or transmission based on the reception of a BI
with the first and/or second bursts and/or transmissions. Also, a
receiver may combine a set of repetitions of a BI that may be
received in or with a set of bursts transmitted together or
contiguously to receive (e.g., successfully) the BI.
[0134] A BI (e.g., the same BI) may be transmitted in one or more
of the bursts of a split burst transmission, for example in all of
the repetitions of a burst or transmission that may be combined
soft-combined to successfully receive the burst or transmission. A
BI may be transmitted in or with a set of bursts, for example a BI
may be repeated in or with each of a set of bursts that may be
transmitted together or contiguously in time.
[0135] In an example, a BI may be transmitted and/or received in a
set of time/frequency resources (e.g., of a transmission or a burst
transmission). The time/frequency resources may be resource
elements (REs). A RE may comprise a set of subcarriers in a
frequency or at least one symbol (e.g., in time). The
time/frequency resources that may be used for a BI transmission may
be different than the resources used for a burst transmission. For
example the burst transmission may be rate-matched around the
time/frequency resources (e.g., the REs) that may be used for a BI
transmission. Also, any increment of time resources as discussed
herein may contain a BI. Further, a BI may be or may be included in
a control channel and/or in control information (e.g., DL or UL
control information) that may be transmitted with a burst.
[0136] The density (e.g., in time/frequency resources such as REs)
of a BI signal/sequence or pattern of one or more signals/sequences
may be a function of a CE level that may be needed or used. The
pattern may be repeated in a time unit or time resource (e.g, a
subframe or slot) to achieve a gain (e.g., a desired gain). The
density may be higher for a higher CE level (e.g., for more CE).
Pattern repetition may be increased or higher for a higher CE level
(e.g., for more CE).
[0137] In some cases, non-repeated bursts and/or BIs may be
provided and/or used. Non-repeated bursts and/or BIs may, for
example, be used for a NB transmission such as a NB-IoT
transmission that may use multiple resources to transmit a
transmission (e.g., a channel or transmission block). Non-repeated
bursts and/or BIs may, for example, be used when CE may not be
used.
[0138] In some cases, a BI may be related to or a function of a
WTRU-ID or C-RNTI. A WTRU may (e.g., only) use or combine one or
more bursts that may be intended for it. A WTRU may determine that
a burst may be intended for it based on the BI that may be
associated with and/or transmitted in or with the burst. Also, a
WTRU may transmit a BI in or with a burst based on its WTRU-ID or
C-RNTI. An eNB may determine that a burst may be from a WTRU (e.g.,
a specific WTRU) based on the BI that may be transmitted in or with
the burst.
[0139] In some cases, a BI may be associated with or configured for
a common channel. For example, a WTRU may determine that a burst
may be associated with or configured for a common channel based on
the BI that may be associated with the burst, transmitted in or
with the burst, and/or received by the WTRU in or with the burst.
The WTRU may or may only use or combine one or more bursts that the
WTRU may determine to be associated with or configured for a common
channel, for example to receive and/or decode (e.g., successfully
receive and/or decode) the common channel.
[0140] Although features and elements are described above in
particular combinations, one of ordinary skill in the art will
appreciate that each feature or element can be used alone or in any
combination with the other features and elements. In addition, the
methods described herein may be implemented in a computer program,
software, or firmware incorporated in a computer-readable medium
for execution by a computer or processor. Examples of
computer-readable media include electronic signals (transmitted
over wired or wireless connections) and computer-readable storage
media. Examples of computer-readable storage media include, but are
not limited to, a read only memory (ROM), a random access memory
(RAM), a register, cache memory, semiconductor memory devices,
magnetic media such as internal hard disks and removable disks,
magneto-optical media, and optical media such as CD-ROM disks, and
digital versatile disks (DVDs). A processor in association with
software may be used to implement a radio frequency transceiver for
use in a WTRU, WTRU, terminal, base station, RNC, or any host
computer.
* * * * *