U.S. patent application number 16/475818 was filed with the patent office on 2019-11-21 for collision mitigation procedures for grant-less uplink multiple access.
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, Hanqing Lou, Janet A. Stern-Berkowitz, Xiaofei Wang, Rui Yang.
Application Number | 20190357222 16/475818 |
Document ID | / |
Family ID | 61074548 |
Filed Date | 2019-11-21 |
View All Diagrams
United States Patent
Application |
20190357222 |
Kind Code |
A1 |
Lou; Hanqing ; et
al. |
November 21, 2019 |
COLLISION MITIGATION PROCEDURES FOR GRANT-LESS UPLINK MULTIPLE
ACCESS
Abstract
A wireless transmit/receive unit (WTRU) may receive a grant-less
(GL) transmission configuration that may include a first indication
of a first set of resource blocks (RBs) for a first resource pool
and a second indication of a second set of RBs for a second
resource pool. The WTRU may select a subset of RBs in the first
set, determine a subset of RBs in the second set based on the
selected subset of RBs in the first set, and transmit UL data to
the base station via the determined subset of RBs in the second
set. The WTRU may receive a negative acknowledgement (NAK) with a
third indication for at least one of a first transmission failure
reason and a second transmission reason. The WTRU may adjust a
backoff and determine a retransmission scheme based on the received
third indication, and retransmit the UL data.
Inventors: |
Lou; Hanqing; (Syosset,
NY) ; Wang; Xiaofei; (Cedar Grove, NJ) ; Yang;
Rui; (Greenlawn, NY) ; Beluri; Mihaela C.;
(Jericho, NY) ; Stern-Berkowitz; Janet A.; (Little
Neck, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
IDAC HOLDINGS, INC. |
Wilmington |
DE |
US |
|
|
Assignee: |
IDAC HOLDINGS, INC.
Wilmington
DE
|
Family ID: |
61074548 |
Appl. No.: |
16/475818 |
Filed: |
January 5, 2018 |
PCT Filed: |
January 5, 2018 |
PCT NO: |
PCT/US2018/012607 |
371 Date: |
July 3, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62443389 |
Jan 6, 2017 |
|
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62565576 |
Sep 29, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 4/70 20180201; H04W
72/042 20130101; H04W 72/02 20130101; H04W 74/0833 20130101; H04L
5/0055 20130101; H04W 72/082 20130101; H04W 74/085 20130101 |
International
Class: |
H04W 72/08 20060101
H04W072/08; H04L 5/00 20060101 H04L005/00; H04W 74/08 20060101
H04W074/08; H04W 4/70 20060101 H04W004/70 |
Claims
1. A wireless transmit/receive unit (WTRU) for grant-less (GL)
uplink (UL) transmissions, the WTRU comprising: a transceiver
configured to receive one or more GL transmission configurations,
including a first indication of a first set of resource blocks
(RBs) for a first resource pool, and a second indication of a
second set of RBs for a second resource pool; a processor
operatively coupled to the transceiver, the processor configured to
select a subset of RBs in the first set; the processor configured
to determine a subset of RBs in the second set based on the
selected subset of RBs in the first set; the processor and the
transceiver configured to transmit UL data, via the determined
subset of RBs in the second set, to a base station; the transceiver
configured to receive a negative acknowledgement (NAK) with a third
indication for at least one of a first transmission failure reason
and a second transmission failure reason, wherein the first
transmission failure reason is due to UL collision and the second
transmission failure reason is due to UL low Signal-to-Noise Ratio
(SNR); the processor configured to adjust a backoff and determine a
retransmission scheme based on the received third indication,
wherein on a condition that the third indication is for the first
transmission failure reason, the adjustment is increasing the
backoff and the retransmission of the UL data is self-decodable;
and the processor and the transceiver configured to retransmit the
UL data to the base station using the adjusted backoff and
determined retransmission scheme.
2. The WTRU of claim 1, wherein a total number of RBs in the first
set is greater than a total number of RBs in the second set.
3. The WTRU of claim 1, wherein the first resource pool is for at
least one of WTRU identity (ID) information and control information
for the WTRU, and the second resource pool is for data
information.
4. The WTRU of claim 1, wherein the subset of RBs in the first set
are selected randomly.
5. The WTRU of claim 1, wherein the subset of RBs in the first set
are selected using a random access procedure and a backoff
procedure.
6. The WTRU of claim 5, wherein the random access procedure and the
backoff procedure are based on one or more of a WTRU priority, a
traffic type of UL data, and the received one or more GL
transmission configurations.
7-8. (canceled)
9. The WTRU of claim 1, wherein on a condition that the third
indication is for the second transmission failure reason, the
adjustment is decreasing the backoff and the retransmission of the
UL data uses incremental redundancy (IR)/Chase combining (CC)
hybrid automatic repeat request (HARQ) combining.
10. The WTRU of claim 1, wherein a time period between the
reception of the GL transmission configuration and a transmission
of the UL data is based on a backoff, and a time period between a
transmission of the UL data and a retransmission of the UL data is
based on a backoff.
11. The WTRU of claim 1, wherein adjusting the backoff includes
adjusting a backoff impact factor.
12. The WTRU of claim 1, wherein the NAK is an RB based NAK.
13. The WTRU of claim 1, further comprising: the processor and the
transceiver configured to transmit at least one of WTRU ID
information for the WTRU and UL control information for the WTRU,
via the selected subset of RBs in the first set, to a base
station.
14. The WTRU of claim 1, wherein an RB group (RBG) includes one or
more RBs.
15. A method for use in a base station for grant-less (GL) uplink
(UL) reception, the method comprising: transmitting one or more GL
transmission configurations, including a first indication of a
first set of resource blocks (RBs) for a first resource pool and a
second indication of a second set of RBs for a second resource
pool; determining whether UL data has been received successfully,
via a subset of RBs within the second set, from a first WTRU; on a
condition that the UL data has not been received successfully,
determining, based on a first resource pool to second resource pool
mapping, whether the first WTRU and at least a second WTRU have
selected the subset of RBs of the second set; on a condition that
the first WTRU and at least the second WTRU have selected the
subset of RBs of the second set, transmitting to the WTRU a
negative acknowledgement (NAK) with a third indication for a first
transmission failure reason and receiving from the WTRU a UL
self-decodable data retransmission, wherein the first transmission
failure reason is due to UL collision; and on a condition that the
first WTRU and at least the second WTRU have not selected the
subset of RBs of the second set, transmitting to the WTRU a NAK
with a third indication for a second transmission failure reason,
wherein the second transmission failure reason is due to UL low
Signal-to-Noise Ratio (SNR).
16. The method of claim 15, wherein a total number of RBs in the
first set is greater than a total number of RBs in the second
set.
17. The method of claim 15, wherein the first resource pool is for
at least one of WTRU identity (ID) information and control
information, and the second resource pool is for data
information.
18. (canceled)
19. The method of claim 15, further comprising: receiving, via a
first subset of RBs in the first set and a second subset of RBs in
the first set, UL control information.
20. The method of claim 15, further comprising: receiving, via a
first subset of RBs in the first set, WTRU ID information for the
first WTRU, and, via a second subset of RBs in the first set, WTRU
ID information for the second WTRU.
21. A method for use in a wireless transmit/receive unit (WTRU) for
grant-less (GL) uplink (UL) transmissions, the method comprising:
receiving one or more GL transmission configurations, including a
first indication of a first set of resource blocks (RBs) for a
first resource pool, and a second indication of a second set of RBs
for a second resource pool; selecting a subset of RBs in the first
set; determining a subset of RBs in the second set based on the
selected subset of RBs in the first set; transmitting UL data, via
the determined subset of RBs in the second set, to a base station;
receiving a negative acknowledgement (NAK) with a third indication
for at least one of a first transmission failure reason and a
second transmission failure reason, wherein the first transmission
failure reason is due to UL collision and the second transmission
failure reason is due to UL low Signal-to-Noise Ratio (SNR);
adjusting a backoff and determining a retransmission scheme based
on the received third indication, wherein on a condition that the
third indication is for the first transmission failure reason, the
adjustment is increasing the backoff and the retransmission of the
UL data is self-decodable; and retransmitting the UL data to the
base station using the adjusted backoff and determined
retransmission scheme.
22. The method of claim 21, wherein a total number of RBs in the
first set is greater than a total number of RBs in the second
set.
23. The method of claim 21, wherein the first resource pool is for
at least one of WTRU identity (ID) information and control
information for the WTRU, and the second resource pool is for data
information.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 62/443,389 filed Jan. 6, 2017 and U.S. Provisional
Application No. 62/565,576 filed Sep. 29, 2017, the contents of
which are hereby incorporated by reference herein.
BACKGROUND
[0002] For each generation of wireless protocols, standards are
developed to address mobile communications needs for future
technologies. Enhanced mobile broadband (eMBB), massive
machine-type communications (mMTC) and
ultra-reliable-and-low-latency communications (URLLC) are several
examples of technology that may demand specific performance
requirements. These examples may require standards, such as the
design of new modulation and coding schemes, waveforms, feedback
processes, beamforming mechanisms, as well as new multiplex access
methods.
[0003] Applications for a new generation of wireless technology,
New Radio (NR), also known as Next Generation Radio or Fifth
Generation (5G), can be summarized under three main categories:
eMBB, mMTC and URLLC. Under each category, there are a wide set of
applications that are considered for various needs and deployment
scenarios that mandate specific performance requirements. For
example, mMTC and URLLC applications range from automotive to
health, agriculture, utilities and logistics industries.
Realization of mMTC and URLLC features may require the design of
new modulation and coding schemes, waveforms, feedback processes,
beamforming mechanisms, as well as new multiplex access
methods.
[0004] For mMTC applications, it is expected that the system would
be able to support up to one million mMTC devices per square
kilometer, but transmission delay for such applications is not as
critical as for other applications. For URLLC applications, the
user equipment (UE) or wireless transmit/receive unit (WTRU)
density per cell is significantly less but such applications call
for a target delay of shorter than 1 millisecond (ms), along with a
high reliability of 10-5 error probability for a 32 byte message.
Despite the differences of these two use cases, they both require a
new uplink multiple access (MA) method to enable them to achieve
their target performance indicators.
SUMMARY
[0005] A system, method, and device may transmit data using
grant-less (GL) transmissions. Specifically, a base station may
send a GL transmission configuration to a wireless transmit/receive
unit (WTRU) that may include a first indication of a first set of
resource blocks (RBs) for a first resource pool and a second
indication of a second set of RBs for a second resource pool. The
base station may be a next generation Node-B (gNB). The WTRU may
then select a subset of RBs in the first set and may determine a
subset of RBs in the second set based on the selected subset of RBs
in the first set. Further, the WTRU may transmit UL data to the
base station via the determined subset of RBs in the second set.
The base station may determine whether the UL data has been
received successfully from the WTRU. If the UL data has not been
received successfully, the base station may determine, based on a
first resource pool to second resource pool mapping, whether the
WTRU and another WTRU have selected the subset of RBs of the second
set. If the WTRU and another WTRU have selected the subset of RBs
of the second set, the base station may transmit a negative
acknowledgement (NAK) with a third indication for a first
transmission failure reason. If the WTRU and another WTRU have not
selected the subset of RBs of the second set, the base station may
transmit a NAK with a third indication for a second transmission
failure reason. The WTRU may then adjust a backoff and determine a
retransmission scheme based on the received third indication.
Further, the WTRU may retransmit the UL data to the base station
using the adjusted backoff and the determined retransmission
scheme.
[0006] In a further example, a total number of RBs in the first set
may be greater than a total number of RBs in the second set. In an
additional example, the first resource pool may be for at least one
of WTRU identity (ID) information and control information for the
WTRU, and the second resource pool may be for data information.
[0007] Further, the subset of RBs in the first set may be selected
randomly. Also, the subset of RBs in the first set may be selected
using a random access procedure and a backoff procedure. In an
example, the random access procedure and the backoff procedure may
be based on one or more of a WTRU priority, a traffic type of UL
data, and the received one or more GL transmission
configurations.
[0008] In addition, the first transmission failure reason may be
due to UL collision and the second transmission failure reason may
be due to UL low Signal-to-Noise Ratio (SNR). Further, if the third
indication is for the first transmission failure reason, the
adjustment may be increasing the backoff and the retransmission of
the UL data may be self-decodable. Also, if the third indication is
for the second transmission failure reason, the adjustment may be
decreasing the backoff and the retransmission of the UL data may
use incremental redundancy (IR)/Chase combining (CC) hybrid
automatic repeat request (HARQ) combining.
[0009] In another example, a time period between the reception of
the GL configuration and a transmission of the UL data may be based
on a backoff. Also, a time period between a transmission of the UL
data and a retransmission of the UL data may be based on a backoff.
Further, adjusting the backoff may include adjusting a backoff
impact factor. In addition, the NAK may be an RB based NAK.
[0010] In a further example, the WTRU may transmit at least one of
WTRU ID information for the WTRU and UL control information for the
WTRU, via the selected subset of RBs in the first set, to a base
station. In an example, the control information for the WTRU may
include the WTRU ID. Also, the RBs may be within an RB group (RBG).
Also, the mapping may use WTRU ID information for both WTRUs. In an
additional example, if the UL data has been received successfully
by the base station, the base station may send an acknowledgement
(ACK) to the WTRU.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] 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:
[0012] FIG. 1A is a system diagram illustrating an example
communications system in which one or more disclosed embodiments
may be implemented;
[0013] FIG. 1B is a system diagram illustrating an example wireless
transmit/receive unit (WTRU) that may be used within the
communications system illustrated in FIG. 1A;
[0014] FIG. 10 is a system diagram illustrating an example radio
access network (RAN) and an example core network (CN) that may be
used within the communications system illustrated in FIG. 1A;
[0015] FIG. 1D is a system diagram illustrating a further example
RAN and a further example CN that may be used within the
communications system illustrated in FIG. 1A;
[0016] FIG. 2 is a timing diagram illustrating an example
scheduling request (SR) process in Long Term Evolution (LTE);
[0017] FIG. 3 is a flow diagram illustrating an example of a WTRU
identity (ID)/control pool based random access procedure;
[0018] FIG. 4 is a flow diagram illustrating an example of a data
pool based random access procedure;
[0019] FIG. 5 is a flow diagram illustrating an example of an
ID/Control pool based random access procedure with mixed grant-less
(GL) and grant-based (GB) transmission;
[0020] FIG. 6 is a flow diagram illustrating an example of an
ID/control pool based random access procedure for high priority
users;
[0021] FIG. 7 is a flow diagram illustrating an example of an
ID/control pool based random access procedure for mixed priority
users;
[0022] FIG. 8A is a frame format diagram illustrating an example of
a time division double pool uplink (UL) GL frame format;
[0023] FIG. 8B is a frame format diagram illustrating an example of
a frequency division double pool UL GL frame format;
[0024] FIG. 9 is a frame format diagram illustrating an example of
reception of a GL transmission at the base station;
[0025] FIG. 10 is a flow diagram illustrating an example procedure
for collision detection and signaling;
[0026] FIG. 11 is a flow diagram illustrating an example procedure
for retransmission with a collision/low SNR indication; and
[0027] FIG. 12 is a flow diagram illustrating an example of a WTRU
procedure with a collision/low SNR indication.
DETAILED DESCRIPTION
[0028] FIG. 1A is a diagram illustrating an example communications
system 100 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), zero-tail unique-word
discrete Fourier transform spread orthogonal frequency division
multiplexing (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM),
resource block-filtered OFDM, filter bank multicarrier (FBMC), and
the like.
[0029] As shown in FIG. 1A, the communications system 100 may
include wireless transmit/receive units (WTRUs) 102a, 102b, 102c,
102d, a radio access network (RAN) 104/113, a core network (CN)
106/115, 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, any of which may be
referred to as a station (STA), may be configured to transmit
and/or receive wireless signals and may include a user equipment
(UE), a mobile station, a fixed or mobile subscriber unit, a
subscription-based unit, a pager, a cellular telephone, a personal
digital assistant (PDA), a smartphone, a laptop, a netbook, a
personal computer, a wireless sensor, a hotspot or Mi-Fi device, an
Internet of Things (IoT) device, a watch or other wearable, a
head-mounted display (HMD), a vehicle, a drone, a medical device
and applications (for example, remote surgery), an industrial
device and applications (for example, a robot and/or other wireless
devices operating in an industrial and/or an automated processing
chain contexts), a consumer electronics device, a device operating
on commercial and/or industrial wireless networks, and the like.
Any of the WTRUs 102a, 102b, 102c and 102d may be interchangeably
referred to as a UE.
[0030] The communications systems 100 may also include a base
station 114a and/or 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 CN 106/115, 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, a Home Node B, a
Home eNode-B, a next generation Node-B (gNB), a new radio (NR)
NodeB, a site controller, an access point (AP), a wireless router,
and the like. 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 any number of interconnected base stations
and/or network elements.
[0031] The base station 114a may be part of the RAN 104/113, 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 on one or more carrier frequencies, which may be
referred to as a cell (not shown). These frequencies may be in
licensed spectrum, unlicensed spectrum, or a combination of
licensed and unlicensed spectrum. A cell may provide coverage for a
wireless service to a specific geographical area that may be
relatively fixed or that may change over time. 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 an
embodiment, the base station 114a may employ multiple-input
multiple output (MIMO) technology and may utilize multiple
transceivers for each sector of the cell. For example, beamforming
may be used to transmit and/or receive signals in desired spatial
directions.
[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 (for example,
radio frequency (RF), microwave, centimeter wave, micrometer wave,
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 104/113
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
(DL) Packet Access (HSDPA) and/or High-Speed Uplink (UL) Packet
Access (HSUPA).
[0034] In an 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) and/or LTE-Advanced Pro (LTE-A Pro).
[0035] In an embodiment, the base station 114a and the WTRUs 102a,
102b, 102c may implement a radio technology such as NR Radio
Access, which may establish the air interface 116 using NR.
[0036] In an embodiment, the base station 114a and the WTRUs 102a,
102b, 102c may implement multiple radio access technologies. For
example, the base station 114a and the WTRUs 102a, 102b, 102c may
implement LTE radio access and NR radio access together, for
instance using dual connectivity (DC) principles. Thus, the air
interface utilized by WTRUs 102a, 102b, 102c may be characterized
by multiple types of radio access technologies and/or transmissions
sent to/from multiple types of base stations (for example, an
eNode-B and a gNB). An eNode-B may be referred to as an eNB and the
terms may be used interchangeably herein.
[0037] In other embodiments, the base station 114a and the WTRUs
102a, 102b, 102c may implement radio technologies such as Institute
for Electrical and Electronic Engineers (IEEE) 802.11 (i.e.,
Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide
Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000
1.times., 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.
[0038] The base station 114b in FIG. 1A 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, an industrial facility, an air corridor (for example, for
use by drones), a roadway, 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 an 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 (for example, WCDMA, CDMA2000,
GSM, LTE, LTE-A, LTE-A Pro, NR etc.) to establish a picocell or
femtocell. As shown in FIG. 1A, 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 CN
106/115.
[0039] The RAN 104/113 may be in communication with the CN 106/115,
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. The data may
have varying quality of service (QoS) requirements, such as
differing throughput requirements, latency requirements, error
tolerance requirements, reliability requirements, data throughput
requirements, mobility requirements, and the like. The CN 106/115
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. 1A, it will
be appreciated that the RAN 104/113 and/or the CN 106/115 may be in
direct or indirect communication with other RANs that employ the
same RAT as the RAN 104/113 or a different RAT. For example, in
addition to being connected to the RAN 104/113, which may be
utilizing a NR radio technology, the CN 106/115 may also be in
communication with another RAN (not shown) employing a GSM, UMTS,
CDMA 2000, WiMAX, E-UTRA, or WiFi radio technology.
[0040] The CN 106/115 may also serve as a gateway for the WTRUs
102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110,
and/or the 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/or the internet
protocol (IP) in the TCP/IP internet protocol suite. The networks
112 may include wired and/or wireless communications networks owned
and/or operated by other service providers. For example, the
networks 112 may include another CN connected to one or more RANs,
which may employ the same RAT as the RAN 104/113 or a different
RAT.
[0041] Some or all of the WTRUs 102a, 102b, 102c, 102d in the
communications system 100 may include multi-mode capabilities (for
example, 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. 1A 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.
[0042] FIG. 1B is a system diagram illustrating an example WTRU
102. As shown in FIG. 1B, 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/or other
peripherals 138, among others. It will be appreciated that the WTRU
102 may include any sub-combination of the foregoing elements while
remaining consistent with an embodiment.
[0043] 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 (FPGA) 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. 1B 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.
[0044] The transmit/receive element 122 may be configured to
transmit signals to, or receive signals from, a base station (for
example, 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 an
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/or
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.
[0045] Although the transmit/receive element 122 is depicted in
FIG. 1B 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 (for example,
multiple antennas) for transmitting and receiving wireless signals
over the air interface 116.
[0046] 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 NR and IEEE 802.11, for example.
[0047] 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 (for example, 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).
[0048] 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 (for
example, nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal
hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel
cells, and the like.
[0049] The processor 118 may also be coupled to the GPS chipset
136, which may be configured to provide location information (for
example, 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 (for example, 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.
[0050] 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 and/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, a
Virtual Reality and/or Augmented Reality (VR/AR) device, an
activity tracker, and the like. The peripherals 138 may include one
or more sensors. The sensors may be one or more of a gyroscope, an
accelerometer, a hall effect sensor, a magnetometer, an orientation
sensor, a proximity sensor, a temperature sensor, a time sensor; a
geolocation sensor; an altimeter, a light sensor, a touch sensor, a
magnetometer, a barometer, a gesture sensor, a biometric sensor, a
humidity sensor and the like.
[0051] The WTRU 102 may include a full duplex radio for which
transmission and reception of some or all of the signals (for
example, associated with particular subframes for both the UL (for
example, for transmission) and DL (for example, for reception) may
be concurrent and/or simultaneous. The full duplex radio may
include an interference management unit to reduce and or
substantially eliminate self-interference via either hardware (for
example, a choke) or signal processing via a processor (for
example, a separate processor (not shown) or via processor 118). In
an embodiment, the WTRU 102 may include a half-duplex radio for
which transmission and reception of some or all of the signals (for
example, associated with particular subframes for either the UL
(for example, for transmission) or the DL (for example, for
reception)).
[0052] FIG. 10 is a system diagram illustrating the RAN 104 and the
CN 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 CN 106.
[0053] The RAN 104 may include eNode-Bs 160a, 160b, 160c, 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 160a, 160b, 160c 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 160a, 160b, 160c may
implement MIMO technology. Thus, the eNode-B 160a, for example, may
use multiple antennas to transmit wireless signals to, and/or
receive wireless signals from, the WTRU 102a.
[0054] Each of the eNode-Bs 160a, 160b, 160c 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 UL and/or DL, and the like. As shown in FIG. 10, the
eNode-Bs 160a, 160b, 160c may communicate with one another over an
X2 interface.
[0055] The CN 106 shown in FIG. 10 may include a mobility
management entity (MME) 162, a serving gateway (SGW) 164, and a
packet data network (PDN) gateway (or PGW) 166. While each of the
foregoing elements are depicted as part of the CN 106, it will be
appreciated that any of these elements may be owned and/or operated
by an entity other than the CN operator.
[0056] The MME 162 may be connected to each of the eNode-Bs 162a,
162b, 162c in the RAN 104 via an S1 interface and may serve as a
control node. For example, the MME 162 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 162 may provide a control plane function for
switching between the RAN 104 and other RANs (not shown) that
employ other radio technologies, such as GSM and/or WCDMA.
[0057] The SGW 164 may be connected to each of the eNode-Bs 160a,
160b, 160c in the RAN 104 via the S1 interface. The SGW 164 may
generally route and forward user data packets to/from the WTRUs
102a, 102b, 102c. The SGW 164 may perform other functions, such as
anchoring user planes during inter-eNode-B handovers, triggering
paging when DL data is available for the WTRUs 102a, 102b, 102c,
managing and storing contexts of the WTRUs 102a, 102b, 102c, and
the like.
[0058] The SGW 164 may be connected to the PGW 166, 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.
[0059] The CN 106 may facilitate communications with other
networks. For example, the CN 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 CN 106 may include, or may communicate with, an IP gateway (for
example, an IP multimedia subsystem (IMS) server) that serves as an
interface between the CN 106 and the PSTN 108. In addition, the CN
106 may provide the WTRUs 102a, 102b, 102c with access to the other
networks 112, which may include other wired and/or wireless
networks that are owned and/or operated by other service
providers.
[0060] Although the WTRU is described in FIGS. 1A-1D as a wireless
terminal, it is contemplated that in certain representative
embodiments that such a terminal may use (for example, temporarily
or permanently) wired communication interfaces with the
communication network.
[0061] In representative embodiments, the other network 112 may be
a WLAN.
[0062] A WLAN in Infrastructure Basic Service Set (BSS) mode may
have an Access Point (AP) for the BSS and one or more STAs
associated with the AP. The AP may have an access or an interface
to a Distribution System (DS) or another type of wired/wireless
network that carries traffic in to and/or out of the BSS. Traffic
to STAs that originates from outside the BSS may arrive through the
AP and may be delivered to the STAs. Traffic originating from STAs
to destinations outside the BSS may be sent to the AP to be
delivered to respective destinations. Traffic between STAs within
the BSS may be sent through the AP, for example, where the source
STA may send traffic to the AP and the AP may deliver the traffic
to the destination STA. The traffic between STAs within a BSS may
be considered and/or referred to as peer-to-peer traffic. The
peer-to-peer traffic may be sent between (for example, directly
between) the source and destination STAs with a direct link setup
(DLS). In certain representative embodiments, the DLS may use an
802.11e DLS or an 802.11z tunneled DLS (TDLS). A WLAN using an
Independent BSS (IBSS) mode may not have an AP, and the STAs (for
example, all of the STAs) within or using the IBSS may communicate
directly with each other. The IBSS mode of communication may
sometimes be referred to herein as an ad-hoc mode of
communication.
[0063] When using the 802.11ac infrastructure mode of operation or
a similar mode of operations, the AP may transmit a beacon on a
fixed channel, such as a primary channel. The primary channel may
be a fixed width (for example, 20 megahertz (MHz) wide bandwidth)
or a dynamically set width, set via signaling. The primary channel
may be the operating channel of the BSS and may be used by the STAs
to establish a connection with the AP. In certain representative
embodiments, Carrier Sense Multiple Access with Collision Avoidance
(CSMA/CA) may be implemented, for example in 802.11 systems. For
CSMA/CA, the STAs (for example, every STA), including the AP, may
sense the primary channel. If the primary channel is
sensed/detected and/or determined to be busy by a particular STA,
the particular STA may back off. One STA (for example, only one
station) may transmit at any given time in a given BSS.
[0064] High Throughput (HT) STAs may use a 40 MHz wide channel for
communication, for example, via a combination of the primary 20 MHz
channel with an adjacent or nonadjacent 20 MHz channel to form a 40
MHz wide channel.
[0065] Very High Throughput (VHT) STAs may support 20 MHz, 40 MHz,
80 MHz, and/or 160 MHz wide channels. The 40 MHz, and/or 80 MHz,
channels may be formed by combining contiguous 20 MHz channels. A
160 MHz channel may be formed by combining 8 contiguous 20 MHz
channels, or by combining two non-contiguous 80 MHz channels, which
may be referred to as an 80+80 configuration. For the 80+80
configuration, the data, after channel encoding, may be passed
through a segment parser that may divide the data into two streams.
Inverse Fast Fourier Transform (IFFT) processing, and time domain
processing, may be done on each stream separately. The streams may
be mapped on to the two 80 MHz channels, and the data may be
transmitted by a transmitting STA. At the receiver of the receiving
STA, the above described operation for the 80+80 configuration may
be reversed, and the combined data may be sent to the Medium Access
Control (MAC).
[0066] Sub 1 gigahertz (GHz) modes of operation are supported by
802.11af and 802.11ah. The channel operating bandwidths, and
carriers, are reduced in 802.11af and 802.11ah relative to those
used in 802.11n, and 802.11ac. 802.11af supports 5 MHz, 10 MHz and
20 MHz bandwidths in the TV White Space (TVWS) spectrum, and
802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths
using non-TVWS spectrum. According to a representative embodiment,
802.11ah may support Meter Type Control/Machine-Type Communications
(MTC), such as MTC devices in a macro coverage area. MTC devices
may have certain capabilities, for example, limited capabilities
including support for (for example, only support for) certain
and/or limited bandwidths. The MTC devices may include a battery
with a battery life above a threshold (for example, to maintain a
very long battery life).
[0067] WLAN systems, which may support multiple channels, and
channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and
802.11ah, include a channel which may be designated as the primary
channel. The primary channel may have a bandwidth equal to the
largest common operating bandwidth supported by all STAs in the
BSS. The bandwidth of the primary channel may be set and/or limited
by a STA, from among all STAs in operating in a BSS, which supports
the smallest bandwidth operating mode. In the example of 802.11ah,
the primary channel may be 1 MHz wide for STAs (for example, MTC
type devices) that support (for example, only support) a 1 MHz
mode, even if the AP, and other STAs in the BSS support 2 MHz, 4
MHz, 8 MHz, 16 MHz, and/or other channel bandwidth operating modes.
Carrier sensing and/or Network Allocation Vector (NAV) settings may
depend on the status of the primary channel. If the primary channel
is busy, for example, due to a STA (which supports only a 1 MHz
operating mode) transmitting to the AP, the entire available
frequency bands may be considered busy even though a majority of
the frequency bands remains idle and may be available.
[0068] In the United States, the available frequency bands which
may be used by 802.11ah are from 902 MHz to 928 MHz. In Korea, the
available frequency bands are from 917.5 MHz to 923.5 MHz. In
Japan, the available frequency bands are from 916.5 MHz to 927.5
MHz. The total bandwidth available for 802.11ah is 6 MHz to 26 MHz
depending on the country code.
[0069] FIG. 1D is a system diagram illustrating the RAN 113 and the
CN 115 according to an embodiment. As noted above, the RAN 113 may
employ an NR radio technology to communicate with the WTRUs 102a,
102b, 102c over the air interface 116. The RAN 113 may also be in
communication with the CN 115.
[0070] The RAN 113 may include gNBs 180a, 180b, 180c, though it
will be appreciated that the RAN 113 may include any number of gNBs
while remaining consistent with an embodiment. The gNBs 180a, 180b,
180c may each include one or more transceivers for communicating
with the WTRUs 102a, 102b, 102c over the air interface 116. In one
embodiment, the gNBs 180a, 180b, 180c may implement MIMO
technology. For example, gNBs 180a, 180b may utilize beamforming to
transmit signals to and/or receive signals from the gNBs 180a,
180b, 180c. Also, in an example, gNBs 180a, 180b, 180c may utilize
beamforming to transmit signals to and/or receive signals from the
WTRUs 102a, 102b, 102c. Thus, the gNB 180a, for example, may use
multiple antennas to transmit wireless signals to, and/or receive
wireless signals from, the WTRU 102a. In an embodiment, the gNBs
180a, 180b, 180c may implement carrier aggregation technology. For
example, the gNB 180a may transmit multiple component carriers (not
shown) to the WTRU 102a. A subset of these component carriers may
be on unlicensed spectrum while the remaining component carriers
may be on licensed spectrum. In an embodiment, the gNBs 180a, 180b,
180c may implement Coordinated Multi-Point (CoMP) technology. For
example, WTRU 102a may receive coordinated transmissions from gNB
180a and gNB 180b (and/or gNB 180c).
[0071] The WTRUs 102a, 102b, 102c may communicate with gNBs 180a,
180b, 180c using transmissions associated with a scalable
numerology. For example, the OFDM symbol spacing and/or OFDM
subcarrier spacing may vary for different transmissions, different
cells, and/or different portions of the wireless transmission
spectrum. The WTRUs 102a, 102b, 102c may communicate with gNBs
180a, 180b, 180c using subframe or transmission time intervals
(TTIs) of various or scalable lengths, for example, containing a
varying number of OFDM symbols and/or lasting varying lengths of
absolute time.
[0072] The gNBs 180a, 180b, 180c may be configured to communicate
with the WTRUs 102a, 102b, 102c in a standalone configuration
and/or a non-standalone configuration. In the standalone
configuration, WTRUs 102a, 102b, 102c may communicate with gNBs
180a, 180b, 180c without also accessing other RANs (for example,
such as eNode-Bs 160a, 160b, 160c). In the standalone
configuration, WTRUs 102a, 102b, 102c may utilize one or more of
gNBs 180a, 180b, 180c as a mobility anchor point. In the standalone
configuration, WTRUs 102a, 102b, 102c may communicate with gNBs
180a, 180b, 180c using signals in an unlicensed band. In a
non-standalone configuration WTRUs 102a, 102b, 102c may communicate
with/connect to gNBs 180a, 180b, 180c while also communicating
with/connecting to another RAN such as eNode-Bs 160a, 160b, 160c.
For example, WTRUs 102a, 102b, 102c may implement DC principles to
communicate with one or more gNBs 180a, 180b, 180c and one or more
eNode-Bs 160a, 160b, 160c substantially simultaneously. In the
non-standalone configuration, eNode-Bs 160a, 160b, 160c may serve
as a mobility anchor for WTRUs 102a, 102b, 102c and gNBs 180a,
180b, 180c may provide additional coverage and/or throughput for
servicing WTRUs 102a, 102b, 102c.
[0073] Each of the gNBs 180a, 180b, 180c 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 UL and/or DL, support of network slicing, dual
connectivity, interworking between NR and E-UTRA, routing of user
plane data towards User Plane Function (UPF) 184a, 184b, routing of
control plane information towards Access and Mobility Management
Function (AMF) 182a, 182b and the like. As shown in FIG. 1D, the
gNBs 180a, 180b, 180c may communicate with one another over an Xn
interface.
[0074] The CN 115 shown in FIG. 1D may include at least one AMF
182a, 182b, at least one UPF 184a, 184b, at least one Session
Management Function (SMF) 183a, 183b, and possibly a Data Network
(DN) 185a, 185b. While each of the foregoing elements are depicted
as part of the CN 115, it will be appreciated that any of these
elements may be owned and/or operated by an entity other than the
CN operator.
[0075] The AMF 182a, 182b may be connected to one or more of the
gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may
serve as a control node. For example, the AMF 182a, 182b may be
responsible for authenticating users of the WTRUs 102a, 102b, 102c,
support for network slicing (for example, handling of different
protocol data unit (PDU) sessions with different requirements),
selecting a particular SMF 183a, 183b, management of the
registration area, termination of non-access stratum (NAS)
signaling, mobility management, and the like. Network slicing may
be used by the AMF 182a, 182b in order to customize CN support for
WTRUs 102a, 102b, 102c based on the types of services being
utilized WTRUs 102a, 102b, 102c. For example, different network
slices may be established for different use cases such as services
relying on ultra-reliable low latency (URLLC) access, services
relying on enhanced massive mobile broadband (eMBB) access,
services for MTC access, and/or the like. The AMF 182a, 182b may
provide a control plane function for switching between the RAN 113
and other RANs (not shown) that employ other radio technologies,
such as LTE, LTE-A, LTE-A Pro, and/or non-Third Generation
Partnership Project (3GPP) access technologies such as WiFi.
[0076] The SMF 183a, 183b may be connected to an AMF 182a, 182b in
the CN 115 via an N11 interface. The SMF 183a, 183b may also be
connected to a UPF 184a, 184b in the CN 115 via an N4 interface.
The SMF 183a, 183b may select and control the UPF 184a, 184b and
configure the routing of traffic through the UPF 184a, 184b. The
SMF 183a, 183b may perform other functions, such as managing and
allocating UE IP address, managing PDU sessions, controlling policy
enforcement and QoS, providing DL data notifications, and the like.
A PDU session type may be IP-based, non-IP based, Ethernet-based,
and the like.
[0077] The UPF 184a, 184b may be connected to one or more of the
gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, 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. The UPF
184, 184b may perform other functions, such as routing and
forwarding packets, enforcing user plane policies, supporting
multi-homed PDU sessions, handling user plane QoS, buffering DL
packets, providing mobility anchoring, and the like.
[0078] The CN 115 may facilitate communications with other
networks. For example, the CN 115 may include, or may communicate
with, an IP gateway (for example, an IP multimedia subsystem (IMS)
server) that serves as an interface between the CN 115 and the PSTN
108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c
with access to the other networks 112, which may include other
wired and/or wireless networks that are owned and/or operated by
other service providers. In one embodiment, the WTRUs 102a, 102b,
102c may be connected to a local DN 185a, 185b through the UPF
184a, 184b via the N3 interface to the UPF 184a, 184b and an N6
interface between the UPF 184a, 184b and the DN 185a, 185b.
[0079] In view of FIGS. 1A-1D, and the corresponding description of
FIGS. 1A-1D, one or more, or all, of the functions described herein
with regard to one or more of: WTRU 102a-d, Base Station 114a-b,
eNode-B 160a-c, MME 162, SGW 164, PGW 166, gNB 180a-c, AMF 182a-ab,
UPF 184a-b, SMF 183a-b, DN 185a-b, and/or any other device(s)
described herein, may be performed by one or more emulation devices
(not shown). The emulation devices may be one or more devices
configured to emulate one or more, or all, of the functions
described herein. For example, the emulation devices may be used to
test other devices and/or to simulate network and/or WTRU
functions.
[0080] The emulation devices may be designed to implement one or
more tests of other devices in a lab environment and/or in an
operator network environment. For example, the one or more
emulation devices may perform the one or more, or all, functions
while being fully or partially implemented and/or deployed as part
of a wired and/or wireless communication network in order to test
other devices within the communication network. The one or more
emulation devices may perform the one or more, or all, functions
while being temporarily implemented/deployed as part of a wired
and/or wireless communication network. The emulation device may be
directly coupled to another device for purposes of testing and/or
may perform testing using over-the-air wireless communications.
[0081] The one or more emulation devices may perform the one or
more, including all, functions while not being implemented/deployed
as part of a wired and/or wireless communication network. For
example, the emulation devices may be utilized in a testing
scenario in a testing laboratory and/or a non-deployed (for
example, testing) wired and/or wireless communication network in
order to implement testing of one or more components. The one or
more emulation devices may be test equipment. Direct RF coupling
and/or wireless communications via RF circuitry (for example, which
may include one or more antennas) may be used by the emulation
devices to transmit and/or receive data.
[0082] Multiple access (MA) is a scheme in which multiple users
(for example, multiple WTRUs) gain access to resources monitored
and controlled by a base station and use the resources
simultaneously. In example provided herein, a base station may be
an eNode-B or a gNB and these terms may be used interchangeably and
still be consistent with the examples provided herein. For example,
OFDMA uses several carriers carrying data independently of each
other and not interfering with each other.
[0083] In LTE, uplink access may be enabled by a contention-free or
grant-based procedure as shown in FIG. 2. Any UE referenced in
FIGS. 2-12 may be interchangeable with a WTRU and still be
consistent with the examples provided herein. WTRUs may be
configured to use a specific Physical Uplink Control
Channel/Physical Uplink Shared Channel (PUCCH/PUSCH) resource(s) to
initiate the access process. In an example case where there is an
absence of a scheduled Scheduling Request (SR) resource(s), a WTRU
may kick start the access process through a Random Access Channel
(RACH) procedure.
[0084] FIG. 2 is a timing diagram illustrating an example SR
process in LTE. As shown in an example in timing diagram 200, a
procedure for contention-free uplink access in LTE may assume an SR
interval of 10 milliseconds (ms). The SR process for a
contention-free uplink access can be summarized in the following
main operations. A WTRU may notice the arrival of uplink data at
the uplink buffer of the WTRU 230. The WTRU may then await for a
subframe with an SR transmission opportunity (1-9 ms), and send the
SR using dedicated resources on an uplink control channel (for
example, PUCCH) during the SR transmission opportunity 240. SR
transmission opportunity 240 is earlier in time than SR
transmission opportunity 280 and may be the first available SR
transmission opportunity after the arrival of uplink data at the
uplink buffer of the WTRU 230. Upon reception of the SR, an eNode-B
issues the WTRU an uplink grant for a PUSCH transmission 250, which
may be issued during a regular subframe. After receiving the grant,
the WTRU may send the uplink data 260 on a PUSCH. If required, the
WTRU may also send its buffer status report (BSR) in the same
subframe 260. According to the received BSR, the eNode-B may
schedule resources for a further PUSCH transmission. In a later
time, the transmitted uplink data by the WTRU may be received by
and be available at eNode-B 270.
[0085] As outlined, the SR process requires coordination and
control between the WTRU and eNode-B. Assuming success of the
initial SR transmission on the PUCCH, the completion of the SR
process may take about 20 ms before the actual PUSCH
transmission.
[0086] As discussed herein, an uplink data transmission with an
uplink grant (for example, downlink control information (DCI) for
scheduling) may be referred to as a DCI message, a grant-based
PUSCH transmission (GB-PUSCH), or both. Further, an uplink data
transmission without an uplink grant may be referred to as
grant-less (GL) PUSCH (GL-PUSCH) transmission. The terms
`grant-less` and `grant-free` may be used interchangeably as
discussed herein. A PUSCH transmission may be interchangeably used
with an uplink transmission, an uplink data transmission, and/or an
uplink control information transmission.
[0087] The following are examples of procedures relating to GB
transmission and GL transmission: Contention-based SR transmission
for MA; Independent transmission of SR and GL-PUSCH; Grant-less
Uplink Transmission and hybrid automatic repeat request (HARQ)
Design; Beam selection consideration; Format of Grant-less UL
transmissions; Grant-less Access Resource Provisioning; Resource
sharing between Grant-less and Grant-based UL transmissions;
Grant-less transmission acknowledgement; and/or Grant-less
transmission power control. As discussed herein, a frame format may
include the idea that control information is transmitted before
data. As used herein, data may also be referred to as payload data,
user data or both and still be consistent with the examples
provided.
[0088] With GL transmission, an eNode-B may not be able to
distinguish the transmitting WTRU if the eNode-B fails to decode
the packet transmitted through the GL transmission, which may
contain a WTRU identity (WTRU ID). Moreover, the eNode-B may not be
able to determine whether the transmission failure is due to
collision or instead due to low Signal-to-Noise Ratio (SNR). Thus,
the eNode-B may not be able to use the failed transmission for HARQ
even if it may be usable.
[0089] As used in examples herein, the WTRU ID may be one or more
of an international mobile subscriber identity (IMSI), a temporary
mobile subscriber identity (TMSI), a radio network temporary
identifier (RNTI), an enhanced RNTI (eRNTI), and the like. Further,
the WTRU ID may be expressed in binary form, in digital form, as a
hash function, as a range of numbers, and the like.
[0090] To address issues related to GL transmissions, one or more
embodiments relating to a double contention pool based method may
considered. Also, one or more embodiments relating to
acknowledgement and retransmission may be considered.
[0091] Several examples may use a double contention pool based
method. A contention resource pool may contain resource blocks
which may be used for GL transmission. A contention resource pool
may have two sub-pools: an ID/control pool which may contain
resource blocks (RBs) that may be used by WTRUs to transmit
ID/control related information; and a data pool which may contain
RBs that may be used by WTRUs to transmit uplink data.
[0092] As used in examples herein, RBs may refer to one or more
time resource and one or more frequency resources. In examples, the
time resources may one or more of various length symbols, TTIs and
subframes, and the frequency resources may be one or more of
various length subcarriers, carriers and bandwidths. RBs may be
include contiguous or non-contiguous resources. RBs may be included
in sets of RBs, subsets of RBs or both. RBs may be grouped into one
or more RB groups (RBGs).
[0093] RBs may contain one or more resource elements (REs). As used
in examples herein, REs may refer to one or more fundamental time
resource and one or more fundamental frequency resources. In
examples, the RBs in an ID/control pool may not contain the same
number of REs as in a data pool. In other examples, the RBs in an
ID/control pool may contain the same number of REs as in a data
pool.
[0094] The size of the ID/control pool may be bigger than or equal
to that of the data pool, so that the collision probability in
ID/control pool may be less than that in data pool. Thus,
ID/control information may be better protected than the data
information.
[0095] The transmissions in the ID/control pool may use basic
modulation and coding schemes with a basic number of spatial
streams. For example, the transmission may use the lowest
modulation and coding scheme with single spatial stream. The
modulation coding levels and number of spatial streams used in the
ID/control pool may be pre-defined, pre-determined or both.
[0096] A WTRU may choose one RB from the ID/control pool to
transmit its WTRU ID and corresponding control information. The
WTRU may choose zero or one or more RBs from the data pool to
transmit its uplink data. If the WTRU may choose one RB from the
ID/control pool and zero RBs from the data pool, for example, the
WTRU may transmit ID/control information only, then the
transmission may be considered as an SR. This may be used for a
transmission scheme where a GL transmission is followed by a GB
transmission. In one method, the WTRU may indicate an SR in an
ID/control RB explicitly. For example, one bit may be set to
indicate an SR and no UL GL data transmission would follow.
[0097] ID/control pool and data pool may be partitioned by time
division, frequency division, code division, spatial division, or
some combination of the divisions described herein. In a time
division partition, RBs located in a certain time period may be
allocated for an ID/control pool and RBs located in a
non-overlapping time period may be allocated for a data pool. In a
frequency division partition, RBs located in certain frequency
resources may be allocated for an ID/control pool and RBs located
in a non-overlapping frequency resources may be allocated for a
data pool. In code division partition, a set of orthogonal codes
with good cross-correlation properties may be pre-defined and/or
pre-determined for code division transmission. Further, a subset of
the codes may be selected and allocated for an ID/control pool and
another subset of the codes may be selected and allocated for a
data pool. Also, the two subsets of code division may or may not be
overlapped. In a spatial division partition, some spatial
vectors/beams may be assigned to carry ID/control information and
the rest may be assigned to carry Data information. In a
combination of partitions, the one or more pools may or may not be
overlapping in at least one dimension.
[0098] An ID/control pool and a data pool may have an independent
or dependent relationship of RB sections. For an independent
relationship, the WTRU may select ID/control RB(s) from ID/control
pool(s) and data RB(s) from data pool(s) independently. For
example, the WTRU may signal/indicate the data RB location in the
ID/control RB, thus, there may not be a WTRU ID included in the
data transmission.
[0099] For a dependent relationship, the WTRU may select ID/control
RB(s), data RB(s) or both in a random way. Further, the selection
of corresponding data RB(s), ID/control RB(s) or both may be
determined in a pre-defined or pre-determined way. For example, the
WTRU may use a ID/control RB index to data RB index mapping.
Moreover, the transmission of ID/control information on the
ID/control RB(s) may contain an explicit indication of a timing
offset. For example, a timing offset compared to the start or the
end of the ID/control transmission, and/or resource(s) used to
transmit the data.
[0100] Example access procedures for GL transmission are discussed
herein. In examples discussed herein, a double contention pool
based method may allow the use of different WTRU procedures
depending on the double contention pool setting. One example
includes a WTRU ID/control pool based random access procedure.
[0101] FIG. 3 is a flow diagram illustrating an example of a WTRU
ID/control pool based random access procedure. In an example shown
in flow diagram 300, a WTRU may receive a downlink transmission
with a configuration for GL transmission with N RB(s) utilized as
an ID/control pool(s) and M RB(s) as a data pool(s) 330. The data
pool may be for payload data or user data. When the WTRU intends to
transmit in the GL transmission opportunity, and/or the WTRU
satisfies any restriction pre-defined or announced by the base
station for the GL transmission, if any, the WTRU may choose a
random number R, where R.di-elect cons.[0, R.sub.GL] 340. In
examples, the base station may be an eNode-B or a gNB. R.sub.GL may
be a number pre-defined and/or pre-determined. R.sub.GL may be a
number chosen from a given range [R.sub.min, R.sub.max], where
R.sub.min and R.sub.max may be pre-defined and/or pre-determined
and signaled. In one example, R.sub.GL may be pre-determined by the
base station and signaled in a downlink transmission. For example,
R.sub.GL may be set to N, thus all the intended WTRUs may compete
in a current GL transmission opportunity and reduce transmission
latency. In another example, R.sub.GL may be determined based on
random access protocol and collision conditions. For example,
R.sub.GL may be set to R.sub.min as an initial value and it may be
set to a minimum value of 2R.sub.GL and R.sub.max if the GL
transmission failed. After a successful transmission, R.sub.GL may
be reset to R.sub.min.
[0102] The WTRU may then determine whether R is less than or equal
to N 350. On a condition that R is less than or equal to N, the
WTRU may transmit in the GL transmission opportunity. For example,
the WTRU may choose the R.sup.th RB in the ID/control pool to
transmit ID/control information 370. In another example, the WTRU
may choose a random number R.sub.ID between 1 and N, and use the
R.sub.ID.sup.th RB to transmit ID/control information. In several
examples, the ID/control information may include a WTRU ID or UE
ID.
[0103] In a further example, the WTRU may choose the Q.sup.th RB to
transmit data, such as payload data or user data, where Q=F(R) 380.
F( ) may be a pre-defined and/or a pre-determined function, which
maps integers from 1 to N to integers from 1 to M. In another
example, the WTRU may choose the Q.sub.ID.sup.th RB to transmit
data, where Q.sub.ID=F(R.sub.ID). In any event, R.sub.ID may be the
resource index at which the WTRU transmits its ID/control
information. In addition, the WTRU may transmit its data at the
time offset or slot number T.sub.d=F.sub.t(R.sub.ID, T.sub.ID)
where F.sub.t(R.sub.ID, T.sub.ID) may be a function of R.sub.ID and
T.sub.ID, which are the resource and time offset/slot number,
respectively, at which the WTRU transmits its ID/control
information.
[0104] On a condition that R is greater than N 350, the WTRU may
not transmit in the GL, and may wait for another GL/GB transmission
opportunity 360. The WTRU may also set R=R-N in the new GL.
[0105] In other examples, a double contention pool based method may
provide different WTRU procedures, depending on the double
contention pool setting, for GL transmission. For example, a data
pool based random access procedure may be used by a WTRU.
[0106] FIG. 4 is a flow diagram illustrating an example of a data
pool based random access procedure. In an example shown in flow
diagram 400, a WTRU may receive a downlink transmission with a
configuration for GL transmission with N RBs utilized as WTRU
ID/control pool(s) and M RBs as data pool(s) 430. When the WTRU
intends to transmit in the GL transmission opportunity, and/or the
WTRU satisfies any restriction pre-defined or announced by the base
station for the GL transmission if any, the WTRU may choose a
random number Q, where Q.di-elect cons.[0, Q.sub.GL] 440. R.sub.GL
may be a number pre-defined and/or pre-determined. In examples, the
base station may be an eNode-B or a gNB. R.sub.GL may be a number
chosen from a given range [Q.sub.min, Q.sub.max], where Q.sub.min
and Q.sub.max may be pre-defined and/or pre-determined and
signaled. In one example, Q.sub.GL may be pre-determined by the
base station and signaled in a downlink transmission. For example,
Q.sub.GL may be set to M, thus all the intended WTRUs may compete
in the current GL transmission opportunity and reduce transmission
latency. In another example, Q.sub.GL may be determined based on
random access protocol and collision conditions. For example,
Q.sub.GL may be set to Q.sub.min as initial value and it may be set
to minimum value of 2Q.sub.GL and Q.sub.max if the GL transmission
failed. After a successful transmission, Q.sub.GL may be reset to
Q.sub.min.
[0107] The WTRU may then determine whether Q is less than or equal
to M 450. On a condition that Q is less than or equal to M, the
WTRU may transmit in the GL. For example, the WTRU may choose
Q.sup.th RB in the data pool to transmit uplink data 470. In a
further example, the WTRU may choose a random number Q.sub.ID
between 1 and M, and use the Q.sub.ID.sup.th RB to transmit uplink
data. Further, the WTRU may choose the R.sup.th RB to transmit WTRU
ID/control information, where R=G(Q) 480. G( ) may be a pre-defined
and/or pre-determined function that maps integers from 1 to M to
integers from 1 to N. In a further example, the WTRU may choose the
R.sub.ID.sup.th RB to transmit WTRU ID/control information, where
R.sub.ID=G(Q.sub.ID).
[0108] On a condition Q is greater than M, the WTRU may not
transmit in the GL, and may wait for another GL/GB transmission
opportunity 460. The WTRU may also set Q=Q-M in the new GL.
[0109] In another example, a double contention pool based method
may allow different WTRU procedures depending on the double
contention pool setting, such as an ID/control pool based random
access procedure with mixed GL and GB transmission. In an example
of such a procedure, the first UL transmission may be assumed to be
a GL transmission, while the retransmission may be a GL
transmission or a GB transmission.
[0110] FIG. 5 is a flow diagram illustrating an example of an
ID/Control pool based random access procedure with mixed GL and GB
transmission. In an example shown in flow diagram 500, a WTRU may
receive a downlink transmission with a configuration for GL
transmission with N RBs utilized as ID/control pool(s) and M RBs as
data pool 530. When the WTRU intends to transmit in the GL
transmission opportunity, and/or it satisfies any restriction
pre-defined or announced by the base station for the GL
transmission, if any, the WTRU may choose a random number R, where
R.di-elect cons.[0, R.sub.GL] 540. In examples, the base station
may be an eNode-B or a gNB. R.sub.GL may be a number pre-defined
and/or pre-determined. R.sub.GL may be a number chosen from a given
range [R.sub.min, R.sub.max], where R.sub.min and R.sub.max may be
pre-defined and/or pre-determined and signaled. In one example,
R.sub.GL may be pre-determined by the base station and signaled in
a downlink transmission. For example, R.sub.GL may be set to N,
thus all the intended WTRUs may compete in the current GL
transmission opportunity and reduce transmission latency. In
another example, R.sub.GL may be determined based on random access
protocol and collision conditions. For example, R.sub.GL may be set
to R.sub.min as an initial value and it may be set to minimum value
of 2R.sub.GL and R.sub.max if the GL transmission failed. After a
successful transmission, R.sub.GL may be reset to R.sub.min.
[0111] The WTRU may then determine whether R is less than or equal
to N 550. On a condition that R is less than or equal to N, the
WTRU may transmit in the GL. In a related example, the WTRU may
choose R.sup.th RB in the WTRU ID/control pool to transmit WTRU
ID/control information 570. In a further example, the WTRU may
choose a random number R.sub.ID between 1 and N, and use the
R.sub.ID.sup.th RB to transmit ID/control information. In any
event, the ID/control information may include the WTRU ID. Further,
the WTRU may choose the Q.sup.th RB to transmit data, where Q=F(R)
580. F( ) may be a pre-defined and/or pre-determined function that
maps integers from 1 to N to integers from 1 to M. In a further
example, the WTRU may choose the Q.sub.ID.sup.th RB to transmit
data, where Q.sub.ID=F(R.sub.ID).
[0112] On a condition that R is greater than N, the WTRU may not
transmit in the GL, and may wait for the next transmission
opportunity 560, which may be a GL transmission opportunity or a GB
transmission opportunity. The WTRU may also set R=R-N. In an
example, when the next transmission opportunity is GB, the WTRU may
transmit the scheduled data 565. For example, the WTRU may discard
R, thus, a new random number may need to be drawn within the range
(0, R.sub.GL] for next GL transmission. R.sub.GL may be reset to
R.sub.min or pre-determined by an base station. In another example,
the WTRU may save R and use it for next potential GL transmission.
Also, when the next transmission opportunity is a GL transmission
opportunity, the WTRU may continue to use the updated R value and
compare it with N.
[0113] The examples discussed herein with regard to the ID/control
pool based random access procedure with mixed GL and GB
transmission of FIG. 5, and the related description, may be
extended to a data pool procedure. For example, an ID/control pool
based procedure example may be extended to a data pool based
procedure example by replacing R with Q and replacing N with M.
[0114] In other examples, a double contention pool based method may
allow different WTRU procedures depending on the double contention
pool setting, such as an ID/control pool based random access
procedure for high priority users. In such examples, users may have
critical requirements for latency and reliability, such as URLLC
users. In such cases, the user may be allowed multiple transmission
chances in one or more of the GL transmission opportunities to
further reduce the probability of collision. For example, the user
may be allowed to use two ID/control RBs and one or two Data
RBs.
[0115] FIG. 6 is a flow diagram illustrating an example of an
ID/control pool based random access procedure for high priority
users. In an example shown in flow diagram 600, a WTRU may receive
a downlink transmission with a configuration for GL transmission
with N RBs utilized as WTRU ID/control pool(s) and M RBs as data
pool(s) 630. In an example, the WTRU may be a WTRU with critical
requirements for latency and reliability. For example, the WTRU may
be a URLLC WTRU. The configuration may indicate allowing two
transmission opportunities for a certain class of user, for
example, WTRUs with critical requirements for latency and
reliability. In an example, the class of users may be URLLC WTRUs.
In a further example, the multiple transmission rule for GL may be
pre-determined/pre-defined or signaled in an additional manner or
an alternative manner. When the WTRU intends to transmit in the GL
transmission opportunity, and/or it may satisfy any restriction
pre-defined or announced by the base station for the GL
transmission, if any, the WTRU may choose a random number R, where
R.di-elect cons.[0, R.sub.GL] 640. In examples, the base station
may be an eNode-B or a gNB. R.sub.GL may be a number pre-defined
and/or pre-determined. R.sub.GL may be a number chosen from a given
range [R.sub.min, R.sub.max], where R.sub.min and R.sub.max may be
pre-defined and/or pre-determined and signaled. In one example,
R.sub.GL may be pre-determined by the base station and signaled in
a downlink transmission. For example, R.sub.GL may be set to N,
thus all the intended WTRUs may compete in the current GL
transmission opportunity and reduce transmission latency. In
another example, R.sub.GL may be determined based on random access
protocol and collision conditions. For example, R.sub.GL may be set
to R.sub.min as an initial value and it may be set to a minimum
value of 2R.sub.GL and R.sub.max if the GL transmission failed,
After a successful transmission, R.sub.GL may be reset to
R.sub.min.
[0116] The WTRU may then determine whether R is less than or equal
to N 650. On a condition that R is less than or equal to N, the
WTRU may choose a second random integer number R2 in the range of
(0, N) 655. The WTRU may then determine whether F(R)=F(R2) 670. If
F(R)=F(R2), then the WTRU may draw another random integer as R2
655. If F(R).noteq.F(R2) then the WTRU may perform a random access
procedure.
[0117] For ID/control information transmission, the WTRU may choose
the R.sup.th RB in the ID/control pool to transmit ID/control
information 680. In a further example, the WTRU may choose a random
number R.sub.ID between 1 and N, and use the R.sub.ID.sup.th RB to
transmit ID/control information. In any event, the ID/control
information may include a WTRU ID. Also, the WTRU may choose the
R2.sup.th RB in the ID/control pool to transmit ID/control
information. The information transmitted in both RBs may be
duplicated. Also, the transmission on the second RB may be modified
slightly. For example, the transmission may be phase rotated, or
interleaved at a bit level or a symbol level. In another example,
the WTRU may code and modulate the ID/control information with a
given or lower rate and transmit it on two RBs. In another example,
dual carrier modulation may be utilized. For example, a set of
coded bits may be mapped to two modulated symbols using different
constellation mapping and transmitted on the two RBs.
[0118] For data transmissions the WTRU may choose the Q.sup.th RB
to transmit data, where Q=F(R) 690 and F( ) is a pre-defined and/or
pre-determined function, which maps integers from 1 to N to
integers from 1 to M. In a further example, the WTRU may choose the
Q.sub.ID.sup.th RB to transmit data, where Q.sub.ID=F(R.sub.ID).
Also, the WTRU may choose the Q2.sup.th RB to transmit data, where
Q2=F2(R). The information transmitted in both RBs may be
duplicated. The transmission on the second RB may be modified
slightly: for example, it may be phase rotated, or interleaved in
bit level or symbol level. In a further example, the WTRU may code
and modulate the data information with a given rate and transmit it
on two RBs. In another example, dual carrier modulation may be
utilized. For example, a set of coded bits may be mapped to two
modulated symbols using different constellation mapping and
transmitted on the two RBs.
[0119] On a condition that R is greater than N 650, the WTRU may
not transmit in the GL, and may wait for another GL 660. The WTRU
may set R=R-N in the new GL. The examples discussed herein with
regard to the ID/control pool based random access procedure for
high priority users of FIG. 6, and the related description, may be
extended to a data pool procedure.
[0120] In another example, a double contention pool based method
may allow different WTRU procedures depending on the double
contention pool setting, such as an ID/control pool based random
access procedure for mixed priority users. In one such example,
WTRUs (or traffic types) with different priorities may compete and
transmit in a GL transmission opportunity. For example, the
priority may be pre-set by the operator or depend on the type of
the devices. The priority may be associated with users or types of
traffic. For example, some WTRUs may require high reliability and
low latency; while other WTRUs may require high data rate(s). In
another example, the type of traffic such as URLLC, eMBB and mMTC
may have different requirements. Further, in examples, different
types of traffic may have different priorities.
[0121] FIG. 7 is a flow diagram illustrating an example of an
ID/control pool based random access procedure for mixed priority
users. In an examples shown in flow diagram 700, a WTRU may receive
a downlink transmission with a configuration for GL transmission
with N RBs utilized as ID/control pool(s) and M RBs as data pool(s)
720. The WTRU may also receive a set of R.sub.GL values,
R.sub.GL_Set={R.sub.GL.sup.i}, where i=1, . . . , l. l may be the
total number of priorities supported. For higher priority, the
R.sub.GL value may be smaller. In a further example, the
R.sub.GL_set may be predefined and known by the base station(s),
WTRUs or both. In examples, the base station may be an eNode-B or a
gNB. In the case that the WTRU may intend to transmit in the GL
transmission opportunity, and/or that it may satisfy any
restriction pre-defined or announced by the base station for the GL
transmission if any, the WTRU may determine its R.sub.GL based on
its priority 730. In any event, the WTRU may choose a random number
R, where R.di-elect cons.[0,R_GL]. Accordingly, the WTRU may choose
its R.sub.GL from the R.sub.GL set.
[0122] The WTRU may determine whether R is less than or equal to N
750. On a condition that R is less than or equal to N, the WTRU may
transmit in the GL. The WTRU may choose R.sup.th RB in the
ID/control pool to transmit ID/control information 770. In another
example, the WTRU may choose a random number R.sub.ID between 1 and
N, and use the R.sub.ID.sup.th RB to transmit ID/control
information. In any event, the ID/control information may include
the WTRU ID. The WTRU may choose the Q.sup.th RB to transmit data,
where Q=F(R) 780. F( ) may be a pre-defined and/or pre-determined
function, which maps integers from 1 to N to integers from 1 to M.
In another example, the WTRU may choose the Q.sub.ID.sup.th RB to
transmit data, where Q.sub.ID=F(R.sub.ID).
[0123] On a condition R is greater than N 750, the WTRU may not
transmit in the GL, and may wait for another GL/GB transmission
opportunity 760. The WTRU may also set R=R-N in the new GL.
[0124] The examples discussed herein with regard to the ID/control
pool based random access procedure with priority and mixed priority
users of FIGS. 6 and 7, and the related description, may be
extended to data pool examples. In a further example, example
procedures in FIGS. 6 and 7, and the related description, may be
combined. For example, WTRUs with a high priority may follow
methods described herein and determine the R.sub.GL and complete a
transmission as was described with relation to examples methods for
mixed priority users, mixed GL transmission and GB transmission, or
any combination of these examples. Further, while WTRUs are recited
in the figures, and related description, in further examples the
WTRU may be replaced with a type of traffic. For example, types of
traffic may include URLLC traffic, eMBB traffic, mMTC traffic, or
any combination of these traffic types, which may use different
R.sub.GL values.
[0125] In examples, a double contention pool based method may allow
for different WTRU functions, such as mapping function(s) F( )
and/or G( ) which may be pre-defined or pre-determined. In one
example, a ratio may be defined as
K = N M ##EQU00001##
where N may be the RB(s) for ID/control information and M may be
the RB(s) for data. In an example function F(.), integers from 1 to
N may be mapped to integers from 1 to M. F( ) may be defined as
follows:
F ( x ) = { 1 x = 1 round ( x K ) 1 < x < M M x = M ,
Equation ( 1 ) ##EQU00002##
[0126] In an example, the function round(x) may be the closest
integer to number x. Further, function G(.), which may map integers
from 1 to M to integers from 1 to N, may be defined as follows:
G ( x ) = round ( x * K - K 2 ) + rand ( round ( K ) ) . Equation (
2 ) ##EQU00003##
[0127] If G(x)<1, then one may set G(x)=1. If G(x)>N, one may
set G(x)=N. The function round(x) may be the closest integer to
number x, in an example. Additionally, the function rand(x) may be
a random number drawn from 1 to x.
[0128] The equations used in the examples above may vary
mathematically in other situations but the basic ideas may remain
similar. For example, to design/define F( ) which may map a larger
set of the integers to a smaller set of integers, we may use the
ratio of the two integer sets (K in this example) to scale down so
that a subset of integers in the range [1, N] may be mapped to one
integer in the range of [1, M]. The size of every subset may be the
same or may be varied by .+-.1. To design/define G( ), which may
map a smaller set of the integers to a larger set of integers, we
may use the ratio of the two integer sets (K in this example) to
scale up so that an integer in the range of [1, M] may be mapped to
an integer in the range of [1, N] as a first step. Since N may be
greater than M, some integers in the range of [1, N] may not be
mapped. Therefore, in a second step, a random number may be drawn
to spread the mapping to all the integer numbers in the range [1,
N]. In a further example, a user specific value may be used. For
example, the fixed value may be calculated though the WTRU ID, or
through other IDs, and K. In one method, a user specific value may
be determined using mod(WTRU ID, K).
[0129] In examples, frame formats may be considered where the UL
frame format may depend on the division of the ID/control pool and
data pool. For example, a time division double pool frame format
may be used.
[0130] FIG. 8A is a frame format diagram illustrating an example of
a time division double pool UL GL frame format. In an example shown
in FIG. 8A, in a time division double pool frame format a common
preamble 810 may be allocated across all or multiple subcarriers
using the first one or several symbols. RBs allocated for
ID/control pool 820, for example RB 1 (RB 821) through RB 10 (RB
830), may follow in time. These may then be followed by RBs
allocated for data pool 840, for example RB 11 RB 841 through RB 15
849. In this example, ID/control pool and data pool allocation and
the number of RBs available may be explicitly signaled. Mapping
function F( ) and G( ) may be explicitly signaled in the ID/control
information field or pre-defined/pre-determined. For instance,
WTRUs that may use RB.sub.2k+1 and RB.sub.2k+2 in a control pool,
may use RB.sub.11+k in a data pool. For each data resource, there
may be two ID/control resources bonded. A WTRU transmitted on one
of the bonded ID/control resources may use the corresponding data
resources. The ID/control information, transmitted using ID/control
resources, may indicate explicitly or implicitly the anticipated
location of the data transmission, to be transmitted on data
resources.
[0131] Once the ID/control information has been successfully
detected, the base station may determine that whether data
transmission has failed. In examples, the base station may be an
eNode-B or a gNB. If a data transmission has failed, the base
station may further determine whether the transmission failure is
due to collision or too low SNR. For example, the base station may
receive ID/control information on both RB1 (821) and RB2 (822), and
it also may not detect a data transmission on RB 11 (841). In such
an example, the base station may consider a collision may have
occurred on RB 11 (841). In a further example, the base station may
receive ID/control information on RB3 (823), no energy on RB4
(824), and may not detect a transmission on RB12 (842). In such an
example scenario, the base station may consider the cause for the
transmission failure as an SNR that is too low.
[0132] In further examples, frame formats may be considered where a
frequency division double pool frame format may be used. Such
examples may share some similarities with time division double pool
frame formats.
[0133] FIG. 8B is a frame format diagram illustrating an example of
a frequency division double pool UL GL frame format. In an example
shown in FIG. 8B, a common preamble 860 may be allocated across all
or multiple subcarriers using the first one or several symbols. RBs
allocated for ID/control pool 870, such as RB 1 (871) through RB10
(880) may follow and use some frequency resources, for example
upper RBs. Such upper RBs may be overlapping frequency resources.
Further, RBs allocated for data pool 890, such as RB 11 (891)
through RB 15 (899) may use the non-overlapping frequency
resources. The signaling method and transmission failure
determination method may be the same as detailed in the example
with respect to FIG. 8A and accompanying text.
[0134] With the double contention pool method as described herein,
acknowledgement and retransmission schemes may need to be designed
to address possible transmission failures where the control/ID
information may be transmitted separately from data information.
Transmission failure reasons may be classified into classes.
[0135] In an example, transmission failure reasons may be
classified into two classes. In a class, a transmission failure may
be due to collision and a failed transmission may not be saved for
HARQ combining. Further, retransmission may not consider HARQ gain
and may be considered as an independent transmission. In a further
class, a transmission failure may be due to low SNR and a failed
transmission may be saved for HARQ combining. Further,
retransmission may use Chase combining or incremental
redundancy.
[0136] To address possible transmission failures there may be an
acknowledgement procedure for GL transmissions. An eNode-B may
setup a GL transmission opportunity in which WTRUs compete and
transmit UL data. After reception of the UL GL transmission(s), the
eNode-B may send acknowledgement(s) to the WTRU(s).
[0137] Assuming the GL transmission uses double contention pool
based methods as described herein, the base station may send
per-WTRU acknowledgement(s) in a unicast manner by a unified
acknowledgment method or a separate acknowledgement method.
Alternatively, or in addition to, a non-unicast manner such as a
broadcast or multicast may be utilized. In one method, both
per-WTRU acknowledgement and RB acknowledgement may be sent in an
acknowledgement frame. The acknowledgement frame may have multiple
parts. For example, the acknowledgement frame may have two parts.
An example part may be a common information part which carries a RB
acknowledgement. A further part may be a per-WTRU or WTRU specific
information part. In the per-WTRU or WTRU specific information
part, unified acknowledgement or separate acknowledgement methods
may be applied.
[0138] In examples where a unified acknowledgement method is
utilized, a single acknowledgment may be sent to each WTRU. In
different example reception scenarios, the acknowledgement may vary
and may have different meanings. In an example with a condition of
an base station receiving ID/control information and data
correctly, an acknowledgement (ACK) may be sent to indicate the
successful reception. In examples, the base station may be an
eNode-B or a gNB.
[0139] In an example with a condition of an base station receiving
ID/control information but failing to receive Data, a negative
acknowledgement (NAK) may be sent. In a further example, a subfield
in the NAK may be used to indicate the reason for data transmission
failure, such as due to collision, due to slow SNR, or due to an
unknown failure. In a further example, the subfield in the NAK my
indicate a score, such as a quantized value of probability,
representing the estimated probability of each transmission
failure. For example, the data transmission failure may be due to
collision with 60% probability and low SNR with 40%
probability.
[0140] In an example with a condition of an base station failing to
receive ID/control information but receiving data information,
nothing may be sent through per WTRU acknowledgement due to the
loss of the ID. Then, the WTRU may look at an RB acknowledgement
for more information. Further, the WTRU may use the information
carried in the RB acknowledgement to determine the reason for the
ID/control information reception failure.
[0141] In an example with a condition of an base station failing to
receive ID/control information and failing to receive data
information, may be sent through per WTRU acknowledgement due to
the loss of the ID. Then, the WTRU may look at an RB
acknowledgement for more information. Further, the WTRU may use the
information carried in the RB acknowledgement to determine the
reason for the ID/control information reception failure and/or the
data information reception failure.
[0142] In some embodiments, the reason for data transmission
failure may not be signaled explicitly in the acknowledgement.
Further the WTRU may use the information carried in the RB
acknowledgement to determine the reason, such as in the examples
provided herein. In a further example, the WTRU may combine this
information with information from other sources to determine the
reason.
[0143] In examples where separate acknowledgements are utilized, a
multiple acknowledgments may be sent to each WTRU, such as one
acknowledgement for ID/control information, which may be referred
to as ID ACK/NAK, and one acknowledgement for data, which may be
referred to as data ACK/NAK. In different example reception
scenarios, the acknowledgements may vary and have different
meanings. In an example with a condition of an base station
receiving ID/control information and data correctly, an ID
acknowledgement (ID ACK) and a data acknowledgement (Data ACK) may
be sent to indicate the successful reception.
[0144] In an example with a condition of an base station receiving
ID/control information but failing to receive Data, an ID ACK may
be sent and a data negative acknowledgement (Data NAK) may be sent.
Further, a subfield in the Data NAK may be used to indicate the
reason for data transmission failure, such as due to collision, due
to slow SNR, or due to an unknown failure. Further, the subfield in
the Data NAK may indicate a score, such as a quantized value of
probability, representing the estimated probability of each
transmission failure. For example, the data transmission failure
may be due to collision with 60% probability and low SNR with 40%
probability.
[0145] In an example with a condition of an base station failing to
receive ID/control information but receiving data information,
nothing may be sent through per WTRU acknowledgement due to the
loss of the ID. Then, the WTRU may look at an RB acknowledgement
for more information. Further, the WTRU may use the information
carried in the RB acknowledgement to determine the reason for the
ID/control information reception failure.
[0146] In an example with a condition of an base station failing to
receive ID/control information and failing to receive data
information, may be sent through per WTRU acknowledgement due to
the loss of the ID. Then, the WTRU may look at an RB
acknowledgement for more information. Further, the WTRU may use the
information carried in the RB acknowledgement to determine the
reason for the ID/control information reception failure and/or the
data information reception failure.
[0147] In some embodiments, the reason for data transmission
failure may not be signaled explicitly in the acknowledgement.
Further the WTRU may use the information carried in the RB
acknowledgement to determine the reason, such as in the examples
provided herein. In a further example, the WTRU may combine this
information with information from other sources to determine the
reason.
[0148] In examples, RB acknowledgement(s) may be utilized. For
example, the base station may indicate it may not successfully
receive anything on certain RBs. Additionally or alternatively, the
base station may indicate it may successfully receive information
on certain RBs. In one example method, only RBs from ID/control
pool may be acknowledged. In another method, RBs from both
ID/control pool and data pool may be acknowledged. Note, this RB
related acknowledgement may be transmitted in a multi-cast or
broad-cast way.
[0149] In one method, a bitmap based RB acknowledgement may be
used. The bitmap based RB acknowledgement signaling may include one
or more of the following example approaches. For example, the
signaling may include a number of RBs field. This field may be used
to indicate the total number of RBs to be signaled. In a further
example, this field may be used to indicate the total number of
bits in the bitmap.
[0150] Further, the bitmap based RB acknowledgement signaling may
include an RB ACK bitmap. For example, the RB ACK bitmap may be
used to indicate the reception status on N RBs. For example, a
value of 1 for the nth bit may indicate a successful reception on
the nth RB. Additionally or alternatively, a value of 0 for the nth
bit may indicate a transmission failure on the nth RB. The RB order
may be specified or predefined in the system. For example, a RB
order may follow the RB index in the time/frequency domain. For
example, a time domain order may be considered first, and for the
same time domain index, a frequency domain index may be considered.
In a further example method, the RB indices may be used to signal
the transmission failure, transmission success or both.
[0151] FIG. 9 is a frame format diagram illustrating an example of
reception of a GL transmission at the base station. Examples shown
in frame format diagram 900 include an acknowledgment procedure
which may be used with the concepts discussed herein. In examples,
the base station may be an eNode-B or a gNB. In an example shown in
FIG. 9, the base station may receive preamble 910. Further, the
base station may set or configure ten RBs, such as RB1 (921)
through RB10 (930) for a grant-free ID/control pool 920 and 5 RBs,
such as RB11 (941) through RB15 (950) for a grant-free data pool
940. WTRU 1 through WTRU 4 may compete and transmit using UL GL
transmission. In a similar example consistent with the examples
provided in FIG. 9, the base station may configure RBs as a set for
the grant-free ID/control pool 920 which includes ten subsets of
RBs and may configure RBs as a set for the grant-free data pool
940, which includes five subsets of RBs. Further, the usage of the
RBs may be set or configured as in Table 1.
TABLE-US-00001 TABLE 1 Example usage of RBs RB1: WTRU1 transmitted
its ID/control information RB2: WTRU2 transmitted its ID/control
information RB3: WTRU3 transmitted its ID/control information RB6:
WTRU4 transmitted its ID/control information RB11: WTRU1 and WTRU2
transmitted data and collided RB12: WTRU3 transmitted data RB13:
WTRU4 transmitted data Rest of RBs are empty
[0152] In an example of RB usage described in Table 1, per-WTRU
unified acknowledgement using joint acknowledgement may be applied
to examples in FIG. 9. For example, for WTRU1, a NAK may be sent
where the reason for data transmission failure may be collision or
collision with high probability. The base station may predict the
data collision since it received ID/control on both RB1 (921) and
RB2 (922) which may relate to data transmission on RB11 (941). For
WTRU2, a NAK may be sent where the reason for data transmission
failure may be collision or collision with a high probability. The
base station may predict the data collision since it received
ID/control information on both RB1 (921) and RB2 (922) which may be
related to data transmission on RB11 (941). For WTRU3, an ACK may
be sent. For WTRU4, a NAK may be sent where the reason for data
transmission failure may be low SNR or low SNR with a high
probability. The base station may predict the data transmission
failure due to low SNR since it received ID/control information on
RB5 (925), while nothing has been received on RB6 (926). Further,
according to the mapping function F(.), RB5 (925) and RB6 (926) may
be the only two RBs in ID/control pool 920 related to RB13 (945) in
data pool 940.
[0153] In another example of RB usage described in Table 1,
per-WTRU unified acknowledgement using separate acknowledgement may
be applied to example FIG. 9. For example, for WTRU1, an ID ACK and
Data NAK may be sent where the reason for data transmission failure
may be collision or collision with high probability. The base
station may predict the data collision since it received ID/control
on both RB1 (921) and RB2 (922) which may relate to data
transmission on RB11 (941). For WTRU2, an ID ACK and Data NAK may
be sent where the reason for data transmission failure may be
collision or collision with high a probability. The base station
may predict the data collision since it received ID/control
information on both RB1 (921) and RB2 (922) which may be related to
data transmission on RB11 (941). For WTRU3, an ID ACK and Data ACK
may be sent. For WTRU4, an ID ACK and Data NAK may be sent where
the reason for data transmission failure may be low SNR or low SNR
with a high probability. The base station may predict the data
transmission failure due to low SNR since it received ID/control
information on RB5 (925), while nothing has been received on RB6
(926). According to the mapping function F(.), RB5 (925) and RB6
(926) may be the only two RBs in ID/control pool 920 related to
RB13 (945) in data pool 940.
[0154] Further, RB acknowledgement(s) may be applied to examples in
FIG. 9 and Table 1. For example, ACKs may be sent for RB1 (921),
RB2 (922), RB3 (923), RB6 (926), and RB12 (943). Further, NAKs may
be sent for RB11 (941) and RB13 (945).
[0155] FIG. 10 a flow diagram illustrating an example procedure for
collision detection and signaling. In an example shown in flow
diagram 1000, a base station may detect several uplink
transmissions without grant in the allocated resources 1010,
including ID resources and data resources. In examples, the base
station may be an eNode-B or a gNB. The base station may check the
ID field and determine whether the ID field was detected
successfully 1020. If the base station detects energy in one ID
field from a WTRU, but fails to decode valid information, it may
determine a transmission failure on the ID field 1025. In one
example, a base station may transmit an RB based
NAK/acknowledgement indicating that it may experience transmission
failure on the RB, which may carry an ID/control information. If
the base station detects an ID field successfully, the base station
may check the data field and determine whether the ID field was
detected successfully 1030. If the base station receives the data
field successfully, then the base station may send an ACK 1035.
Otherwise, the base station may use the mapping function F( ) to
determine whether other WTRU(s) may transmit using the same data
RB(s) as the WTRU, which may include using the same RE(s) 1040.
Note, the mapping function F( ) may be designed to map multiple
ID/control fields to one data field. Explained differently, WTRUs
that transmit on different ID/control fields may transmit on the
same data field.
[0156] On a condition that other WTRU(s) are transmitting using the
same RE(s) as the WTRU, and accordingly, where the WTRUs transmit
on different ID/control fields and transmit on the same data field,
there may be transmission failure due to collision(s) 1070. In the
event of a transmission failure due to collision, the base station
may take one or more of the following steps. For example, the base
station may send a NAK with a collision/low SNR indication set to 1
back to the WTRU. In a further example, the base station may or may
not remove the buffer depending on the measured signal to inference
and noise ratio (SINR). In an additional example, the
retransmission after failure determination may be self-decodable.
An example of a self-decodable retransmission includes using
retransmission version (RV)=0 and HARQ combining may not be
performed. In another example, the base station may include a New
Data Indicator (NDI) in the acknowledgement to request a new data
transmission. In a further example, the base station may include
the NDI in a configuration of the next GL transmission. If the base
station includes the NDI for the next GL transmission, the base
station may request all of the potential GL transmissions to be new
transmissions. Further, the base station may allow the potential GL
transmissions to be new transmissions.
[0157] On a condition that other WTRU(s) are not transmitting using
the same RE(s) as the WTRU, and accordingly, where the WTRUs
transmit on different ID/control fields and the WTRU do not
transmit on the same data field, there may be transmission failure
due to low SNR 1090. In the event of transmission failure due to
low SNR, the base station may take one or more of the following
steps. For example, the base station may send a NAK with a
collision/low SNR indication set to 0 back to the WTRU In a further
example, the base station may buffer the received data 1095.
Further, the retransmission may use incremental redundancy
(IR)/Chase combining (CC) HARQ. Also, HARQ combining may be
performed. In another example, the base station may include an in
the acknowledgement to request retransmission, where HARQ
combination may be possible. In a further example, the base station
may include the NDI in a configuration of next GL transmission. If
the base station includes the NDI for the next GL transmission, the
base station may request all of the potential GL transmissions to
be retransmissions. Further, the base station may allow the
potential GL transmissions to be retransmissions.
[0158] In an example, a base station may send a GL transmission
configuration to a WTRU that may include a first indication of a
first set of RBs for a first resource pool and a second indication
of a second set of RBs for a second resource pool. The base station
may be a gNB, in an example. The WTRU may then select a subset of
RBs in the first set and may determine a subset of RBs in the
second set based on the selected subset of RBs in the first set.
Further, the WTRU may transmit UL data to the base station via the
determined subset of RBs in the second set. The base station may
determine whether the UL data has been received successfully from
the WTRU. If the UL data has not been received successfully, the
base station may determine, based on a first resource pool to
second resource pool mapping, whether the WTRU and another WTRU
have selected the subset of RBs of the second set. If the WTRU and
another WTRU have selected the subset of RBs of the second set, the
base station may transmit a NAK with a third indication for a first
transmission failure reason. If the WTRU and another WTRU have not
selected the subset of RBs of the second set, the base station may
transmit a NAK with a third indication for a second transmission
failure reason. The WTRU may then adjust a backoff and determine a
retransmission scheme based on the received third indication.
Further, the WTRU may retransmit the UL data to the base station
using the adjusted backoff and the determined retransmission
scheme.
[0159] In a further example, a total number of RBs in the first set
may be greater than a total number of RBs in the second set. In an
additional example, the first resource pool may be for at least one
of WTRU ID information and control information for the WTRU, and
the second resource pool may be for data information.
[0160] Further, the subset of RBs in the first set may be selected
randomly. Also, the subset of RBs in the first set may be selected
using a random access procedure and a backoff procedure. In an
example, the random access procedure and the backoff procedure may
be based on one or more of a WTRU priority, a traffic type of UL
data, and the received one or more GL transmission
configurations.
[0161] In addition, the first transmission failure reason may be
due to UL collision and the second transmission failure reason may
be due to UL low SNR. Further, if the third indication is for the
first transmission failure reason, the adjustment may be increasing
the backoff and the retransmission of the UL data may be
self-decodable. Also, if the third indication is for the second
transmission failure reason, the adjustment may be decreasing the
backoff and the retransmission of the UL data may use IR/CC HARQ
combining.
[0162] In another example, a time period between the reception of
the GL configuration and a transmission of the UL data may be based
on a backoff. Also, a time period between a transmission of the UL
data and a retransmission of the UL data may be based on a backoff.
Further, adjusting the backoff may include adjusting a backoff
impact factor. In addition, the NAK may be an RB based NAK.
[0163] In a further example, the WTRU may transmit at least one of
WTRU ID information for the WTRU and UL control information for the
WTRU, via the selected subset of RBs in the first set, to a base
station. In an example, the control information for the WTRU may
include the WTRU ID. Also, the RBs may be within an RBG. Also, the
mapping may use WTRU ID information for both WTRUs. In an
additional example, if the UL data has been received successfully
by the base station, the base station may send an ACK to the
WTRU.
[0164] Examples procedures are provided herein for retransmission
with a collision/low SNR indication. In example procedures, the
WTRUs may adjust their retransmission scheme(s) to increase a
probability of successful transmission perform collision control to
decrease the collision probability, or both.
[0165] If a WTRU receives many NAKs with collision indications, the
WTRU may determine that it is in a dense network and many WTRUs are
competing for the GL transmission, at which point the WTRU may
determine to back off. If a WTRU receives many NAKs with low SNR
indications, the WTRU may determine to retransmit with a lower
modulation and coding scheme, with a HARQ scheme, use more RBs for
retransmission, or a combination of these.
[0166] FIG. 11 is a flow diagram illustrating an example procedure
for retransmission with a collision/low SNR indication. In an
example shown in flow diagram 1100, a WTRU may receive a NAK for
its GL transmission 1110. With the NAK, there may be a
collision/low SNR indication. The WTRU may receive a GL
transmission configuration with N resource blocks for ID/control
pools and M resource blocks for data pools 1120, where N>=M. The
WTRU may have a predefined or predetermined mapping function F(
).
[0167] Based on the information carried in the NAK frame for a
previous transmission, the WTRU may determine if a NAK with a
collision indication or a NAK with low SNR was received 1130. If
the WTRU receives a NAK with a collision indication, the WTRU may
perform one or more of the following steps. In an example, the WTRU
may prepare the retransmission with self-decodable coding schemes
1140. For example, the WTRU may use RV=0 for a retransmission.
Accordingly, the WTRU may have an NDI included in the packet to
indicate a new transmission. Further, with a collision indication,
the WTRU may think the network is densely deployed and many WTRUs
may try to transmit on the limited GL resources so the WTRU may
reset/increase back off impact factor R.sub.GL 1145. For example,
the WTRU may set R.sub.GL=min(2R.sub.GL, R.sub.max) where R.sub.max
is a predefined or predetermined upper bound of R.sub.GL. The WTRU
may then proceed to step 1155, as explained more fully below.
[0168] Based on the information carried in the NAK frame for a
previous transmission, if the WTRU receives a NAK with a low SNR
indication, the WTRU may perform one or more of the following
steps. In an example, the WTRU may prepare the retransmission with
IR/CC HARQ coding schemes 1135. For example, the WTRU may use any
retransmission version for retransmission and the WTRU may have an
NDI included in the packet to indicate a retransmission. Further,
the WTRU may think low SNR may be the reason for transmission
failure and the WTRU may use a lower level modulation and coding
scheme for a retransmission. the WTRU may reset or increase the
number of allowed RBs N.sub.RB, where the WTRU may be allowed to
use more GL RBs. For example, the WTRU may set N.sub.RB=min(2
N.sub.RB,N) where N is the number of RBs allocated for GL
transmission. Further the WTRU may reset/decrease back off impact
factor R.sub.GL 1150. For example, the WTRU may set
R.sub.GL=max(R.sub.GL/2,R.sub.min) where R.sub.min is a predefined
or predetermined upper bound of R.sub.GL. In one example, R.sub.min
may be set as the number of resource blocks allocated for GL
transmission, M or N, depending on whether an ID/control pool based
random access procedure or a data pool based random access
procedure is used, respectively. For example, with an ID pool based
method, the random number will be compared with an ID/control pool
size N, and with a data pool based method the random number will be
compared with a data pool size M.
[0169] The WTRU may choose a random number R in the range [0,
R.sub.GL), where R.sub.GL is the back off impact factor 1155. If
R<N, then one or more of the following example steps may also be
taken. In an example, the WTRU may choose a new random number R0 in
the range [0,N]. Further, the WTRU may set R0=R. Also, the WTRU may
choose the Roth RB to transmit ID/control information 1180.
Further, the WTRU may choose the Q0.sup.th RB to transmit data,
where Q0=F(R0) 1190. Otherwise, if R<N is not true, then the
WTRU may set R=R-N and the WTRU may back off and may not perform
retransmission this time 1170.
[0170] The examples shown in FIG. 11 include an ID pool based
random access and back off procedure, where the random number may
be compared with the ID pool size N. Alternatively or additionally,
the example may be extended to a data pool based random access and
back off procedure where the random number may be compared with the
data pool size M.
[0171] FIG. 12 is a flow diagram illustrating an example of a WTRU
procedure with a collision/low SNR indication. In an example shown
in flow chart diagram 1200, a WTRU may receive a NAK with a
transmission failure indication. If the transmission failure
indication is set to collision 1210, the WTRU may increase R.sub.p,
the back off impact factor for retransmission 1215. Further, there
may be a maximum number R.sub.max predefined/predetermined/signaled
where R.sub.p may not be bigger than the R.sub.max. In an example,
a NAK which indicates collision may be used in a dense network with
many collisions. Increasing the back off impact factor for
retransmission may reduce the chance of collision in a
retransmission.
[0172] If the transmission failure indication is set to low SNR
1220, the WTRU may decrease R.sub.p, the back off impact factor for
retransmission 1225. The backoff factor may be marginally decreased
because a large backoff may not be needed. Further, there may be a
minimum number R.sub.min predefined/predetermined/signaled where
R.sub.p may not be smaller than the R.sub.min.
[0173] The WTRU may randomly select a number R in [0, R.sub.p]
1230. The WTRU may determine whether R is bigger than the actual
resource pool size N 1240. If R is bigger than the actual resource
pool size N, then it may set R=R-N, back off and wait until the
next grant-free transmission opportunity 1250. Accordingly, the
WTRU may provide a random backoff to reduce collisions. If R is not
than the actual resource pool size N, the WTRU may perform a
retransmission on the R0th ID/control resource and Q0th data
resource, where Q0=f(R0) 1260. In one example, R0 may be set to R.
In another example, R0 may be a random value between 0 and N, where
N is the resource pool size. Accordingly, the WTRU may typically
not backoff for small values of R.sub.p and the backoff may not be
needed if a transmission failure is due to low SNR.
[0174] For the retransmission, if the WTRU receives a NAK due to
collision, the WTRU may perform a self-decodable coding scheme. For
example, the WTRU may use a self-decodable RV in a retransmission,
such as RV=0 1270. The WTRU may signal the RV in the
retransmission. If the WTRU receives a NAK due to low SNR 1280, the
WTRU may perform a retransmission with any RVs. The WTRU may or may
not signal the RV used if it is with a preferred RV order. Further,
the WTRU may use IR/CC HARQ in the retransmission.
[0175] In another example, WTRUs may maintain several counters for
GL transmission failures. For example, the WTRU may have one or
more of a collision counter, a low SNR counter, and/or a
transmission failure counter. The collision counter may be used to
count the number of transmission failures due to collision. In one
example, this counter may be used to count the consecutive
transmission failures due to collision and a successful
transmission may reset the counter to 0. In another example, this
counter may be for long term statistics where it may be an average
number over a sliding window.
[0176] The low SNR counter may be used to count the number of
transmission failures due to low SNR. In one example, this counter
may be used to count the consecutive transmission failures due to
low SNR, and a successful transmission may reset the counter to 0.
In another example, this counter may be for long term statistics
where it may be an average number over a sliding window.
[0177] The transmission failure counter may be used to count the
number of transmission failures. In one example, this counter may
be used to count the consecutive transmission failures due to
collision and/or low SNR, and a successful transmission may reset
the counter to 0. In another example, this counter may be for long
term statistics where it may be an average number over a sliding
window. In a further example, a first counter may be used for
transmission failure due to collision and a second counter may be
used for transmission failure due to low SNR.
[0178] In an example, if the collision counter is high or is bigger
than a threshold, the WTRU may determine that it may be a dense
network where many WTRUs may be competing for the GL transmission.
In such a case, the WTRU may determine to back off.
[0179] If the low SNR counter is high or is bigger than a
threshold, the WTRU may determine that it may need to retransmit
with a lower modulation and coding scheme, with HARQ scheme, using
more RBs for retransmission, or a combination of these.
[0180] 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, UE, terminal, base station, RNC, or any host
computer.
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