U.S. patent application number 16/859939 was filed with the patent office on 2020-10-15 for method and system of bi-directional transmission to improve uplink performance.
The applicant listed for this patent is ZTE (USA) Inc.. Invention is credited to Yifei YUAN.
Application Number | 20200329462 16/859939 |
Document ID | / |
Family ID | 1000004925937 |
Filed Date | 2020-10-15 |
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United States Patent
Application |
20200329462 |
Kind Code |
A1 |
YUAN; Yifei |
October 15, 2020 |
METHOD AND SYSTEM OF BI-DIRECTIONAL TRANSMISSION TO IMPROVE UPLINK
PERFORMANCE
Abstract
In coverage enhancement of machine type communication (MTC), a
downlink transmitted bit stream is jointly encoded with uplink
payload by the terminal. The combined signal is sent on uplink, to
be jointly decoded by the base station that knows the downlink
payload and the joint encoding mechanism at the mobile
terminal.
Inventors: |
YUAN; Yifei; (Iselin,
NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ZTE (USA) Inc. |
Richardson |
TX |
US |
|
|
Family ID: |
1000004925937 |
Appl. No.: |
16/859939 |
Filed: |
April 27, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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15565041 |
Oct 6, 2017 |
10638465 |
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PCT/US16/26570 |
Apr 8, 2016 |
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16859939 |
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62144975 |
Apr 9, 2015 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 2001/0093 20130101;
H04W 72/042 20130101; H04L 5/0037 20130101; H04L 1/243 20130101;
H04L 5/0026 20130101; H04W 72/005 20130101; H04W 4/70 20180201 |
International
Class: |
H04W 72/04 20060101
H04W072/04; H04W 4/70 20060101 H04W004/70; H04L 1/24 20060101
H04L001/24; H04L 5/00 20060101 H04L005/00; H04W 72/00 20060101
H04W072/00 |
Claims
1-20. (canceled)
21. A method of wireless communication comprising, transmitting, by
a base station to at least one of a plurality of terminals, a
downlink message comprising user-specific information to individual
ones of the plurality of terminals; receiving, by the base station
from the at least one of the plurality of terminals, an uplink
message encoded jointly with at least some of information in the
downlink message; and decoding the uplink message based on the
downlink message.
22. The method of claim 21, wherein the user-specific information
comprises at least one of a payload size, a modulation order, a bit
rate, a signal format, a channel coding, or a time-frequency
resource that is different the individual ones of the plurality of
terminals.
23. The method of claim 21, wherein the uplink message is encoded
jointly based on performing a bitwise "exclusive or" operation on
information in the downlink message and information in the uplink
message.
24. The method of claim 21, wherein the plurality of terminals
comprises machine type communication (MTC) devices.
25. A wireless communication device, comprising: a transmitter
configured to transmit, to at least one of a plurality of
terminals, a downlink message comprising user-specific information
to individual ones of the plurality of terminals; a receiver
configured to receive, from the at least one of the plurality of
terminals, an uplink message encoded jointly with at least some of
information in the downlink message; and a processor configured to
decode the uplink message based on the downlink message.
26. The device of claim 25, wherein the user-specific information
comprises at least one of a payload size, a modulation order, a bit
rate, a signal format, a channel coding, or a time-frequency
resource that is different the individual ones of the plurality of
terminals.
27. The base station of claim 25, wherein the uplink message is
encoded jointly based on performing a bitwise "exclusive or"
operation on information in the downlink message and information in
the uplink message.
28. The base station of claim 25, wherein the plurality of
terminals comprises machine type communication (MTC) devices.
29. A method of wireless communication, comprising: receiving, by a
terminal from a base station, a downlink message that is
user-specific to the terminal; encoding an uplink message jointly
with at least some of information in the downlink message; and
transmitting the uplink message that is jointly encoded to the base
station.
30. The method of claim 29, wherein at least one of a payload size,
a modulation order, a bit rate, a signal format, a channel coding,
or a time-frequency resource of the downlink message is
user-specific to the terminal.
31. The method of claim 29, wherein encoding comprises performing a
bitwise "exclusive or" operation on information in the downlink
message and information in the uplink message.
32. The method of claim 29, wherein the terminal comprises a
machine type communication (MTC) device.
33. A wireless communication device, comprising: a receiver
configured to receive, from a base station, a downlink message that
is user-specific to the terminal; an encoder configured to encode
an uplink message jointly with at least some of information in the
downlink message; and a transmitter configured to transmit, to the
base station, the uplink message that is jointly encoded.
34. The device of claim 33, wherein at least one of a payload size,
a modulation order, a bit rate, a signal format, a channel coding,
or a time-frequency resource of the downlink message is
user-specific to the terminal.
35. The device of claim 33, wherein the encoder is configured to
encode the uplink message jointly based on performing a bitwise
"exclusive or" operation on information in the downlink message and
information in the uplink message.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a method and system of
hi-directional transmission between a base station and a terminal
to improve uplink performance, and to the use of network coding
between downlink and uplink,
BACKGROUND OF THE INVENTION
[0002] Machine type communication (MTC) is considered as one of the
major driving forces of a future generation of cellular
communications. Likely application scenarios for MTC feature
numerous low-cost machine-type devices connecting to the network.
The data packet size of MTC is usually smaller than that of
human-to-human cellular communications. Because of the smaller data
packet sizes, iterative types of channel codes such as turbo codes
or low density parity check (LDPC) codes would provide less coding
gain with MTC than is usual with the longer human-to-human packet
sizes. To make the matter worse, some types of MTC devices, like
meter reading for utilities, are often installed in a basement or
other area with poor signal penetration, which requires a superb
link budget to overcome the deep penetration loss.
[0003] Coverage enhancements can be achieved in several ways. One
approach is to use CDMA-like signals that have lower peak to
average ratio, less control overhead, etc. A second approach is to
use more antennas, either at the transmitter with beamforming or to
obtain transmit diversity gain, or at the receiver to obtain
aperture or receive diversity gain. A third approach is repetition,
which has been used in 3GPP LTE, for the reason that LTE is an
OFDMA system and there is no compelling reason to overhaul that
fundamental just for the sake of coverage. Note that transmission
time interval (TTI) bundling enhancements, as described in Y. Yuan,
et al, "LTE-Advanced coverage enhancements," IEEE Comm. Mag.
October, 2014, pp, 153-159, as one type of repetition, are already
specified in Rel-11 LTE for uplink Voice over IP (VoIP) and data
traffic carried on physical uplink shared channel (PUSCH). In
Rel-12 and Rel-13 LTE, repetition is believed to the most effective
technique to achieve good coverage of narrow-band MTC and has been
extended to many other physical channels, for example, primary
broadcast channel (PBCH), physical downlink shared channel (PDSCH),
enhanced physical downlink control channel (EPDCCH), etc.
[0004] Network coding has attracted attention as an academic
research topic. Its most promising use scenarios include relay,
mesh networks, and device to device (D2D) communications.
[0005] Network coding takes advantage of the broadcast nature of
wireless communications, and can make use of not-directly targeted
transmission(s) to improve the redundancy of transmissions in a
coordinated manner.
[0006] Significant impact on standards is expected if network
coding is to be adopted in LTE. Since the channel coding would
remain largely unchanged in LTE/LTE-A, network coding, which
inevitably affects the channel codes, has not been studied in 3GPP
LTE.
SUMMARY
[0007] In accordance with one aspect, there is provided a method of
transmitting one or more signals in a downlink message for multiple
mobile terminals to receive, and then each terminal, upon
successful decoding of one or more of the one or more signals,
incorporates information carried in the downlink signals into its
own information bits to be sent in an uplink message. The method
comprises two processes, performed in the downlink and the uplink,
respectively. The first process involves a downlink transmission in
which information can be sent from a base station either in
broadcast mode or in user-specific mode. The second process
concerns the integration between the information sent by the base
station and the terminal's own information, to form a jointly coded
bit stream for uplink transmission.
[0008] In an embodiment, the information carried in the downlink
transmission can be common to all the terminals being served by the
base station. The common information is sent in the broadcast mode,
with the same ID common to all the terminals.
[0009] In an embodiment, the information carried in the downlink
transmission can be user-specific so that different terminals would
receive different information. Different terminals may also receive
different size payloads of information.
[0010] In an embodiment, the user-specific message is transmitted
in a dedicated channel, which makes it possible for any or all of
the signal format, channel coding and occupied
time-frequency-spatial resources targeted to each mobile terminal
to be different from others.
[0011] In an embodiment, the integration of the downlink
information payload and the uplink. information payload can result
in a combined bit stream of the same size as the original uplink
information payload. In that embodiment, the downlink bits are
effectively completely absorbed in the uplink bit stream.
[0012] In another embodiment, the integration of the downlink
information payload and the uplink information payload can result
in a combined bit stream of larger size than the original uplink
information.
[0013] In another aspect, there is provided a system that involves
a base station transmitting one or more signals in the downlink for
multiple mobile terminals to receive, and then each terminal upon
successfully decoding one or more signals, would incorporate the
information carried in the downlink into its own information bits
to be sent in the uplink. The system implements two processes,
performed in the downlink and the uplink, respectively. The first
process involves downlink transmission in which the carried
information can be sent from base station in either broadcast mode
or user-specific mode. The second process concerns the integration
between the information sent by the base station, and the
terminal's own information, to form a jointly coded bit stream for
uplink transmission.
[0014] In another aspect, there are provided terminals, base
stations, computer programs and other machine-readable
instructions, and non-volatile computer-readable storage media
containing such instructions, for putting the methods and systems
into effect.
[0015] The foregoing and other features and advantages will become
more apparent in light of the following detailed description of
preferred embodiments, as illustrated in the accompanying figures.
As will be realized, the invention is capable of modifications in
various respects, all without departing from the invention.
Accordingly, the drawings and the description are to be regarded as
illustrative in nature, and not as restrictive.
BRIEF DESCRIPTION OF THE FIGURES
[0016] The above and other aspects, features, and advantages of the
present invention may be more apparent from the following more
particular description of embodiments thereof, presented in
conjunction with the following drawings. In the drawings:
[0017] FIG. 1 illustrates the downlink stage.
[0018] FIG. 2 illustrates the uplink stage.
[0019] FIG. 3 is a flowchart.
DETAILED DESCRIPTION
[0020] A better understanding of various features and advantages of
the present methods and devices may be obtained by reference to the
following detailed description of illustrative embodiments of the
invention and accompanying drawings. Although these drawings depict
embodiments of the contemplated methods and devices, they should
not he construed as foreclosing alternative or equivalent
embodiments apparent to those of ordinary skill in the subject
art.
[0021] Referring to the accompanying drawings, and initially mainly
to FIGS. 1 and 2, there is illustrated an example of integrating
downlink bearing bits and an uplink pay load and jointly encoding
the downlink bits and the uplink bits to form a combined bit stream
to be sent in the uplink.
[0022] The present method and devices apply a principle of network
coding where bit streams coming from different nodes can be added
together to improve the overall system capacity. Such principle is
particularly applied in a scenario of machine type communication
(MTC) where coverage requirements can be very challenging,
especially for an uplink that is limited by the maximum
transmitting power and the number of antennas at the terminals. The
situation can be aggravated because uplinking terminals may be
devices such as utility meters installed in basements, from which
good transmission is difficult to obtain. The situation of the
downlink tends to be less difficult, because the base stations can
easily have higher transmitting power and a larger number of
antennas than the terminals. Hence, some link budget imbalance
between downlink and uplink can be compensated by jointly decoding
the downlink and uplink signals.
[0023] In the example shown in FIGS. 1 and 2, only two terminals
are shown, in the form of mobile stations denoted as user equipment
UE1 and UE2, respectively. However, there may be more or fewer
terminals, and some or all of the terminals may be stationary
rather than mobile.
[0024] Referring now also to FIG. 3, during a downlink transmission
stage, the base station sends signals bearing information bit
streams d1 and d2 to terminals UE1 and UE2, respectively. These two
streams can in general be different, which means that they can be
encoded and modulated with different code rates and modulation
order, and then transmitted to each HE with dedicated resources.
This provides the freedom to adjust the downlink transmission
payload individually to each mobile station. Since uplink quality
of each mobile station may be different, the optimum size and
content of the downlink payload to participate the joint coding may
be different for different uplink connections.
[0025] Alternatively, bit streams d1 and d2 can be the same, so
that the base station can broadcast to both UE1 and UE2, using the
code rate, modulation, and radio resources common to them. While
the broadcast transmission has less flexibility in controlling the
downlink data rate per link, it has less overhead and may be
preferable in some scenarios. In a larger system with many
terminals UE1, UE2, . . . , some or all of the terminals may be
organized in groups with a common transmission to all the terminals
in a group, and different transmissions to terminals not in the
same group.
[0026] When a terminal UE1 or UE2 successfully decodes the
respective bit stream d1 or d2, the terminal then encodes its own
uplink payload, u1 or u2, respectively, jointly with the respective
downlink payload d1 or d2, to form an uplink payload f(d, u). The
joint coding can be a type of network coding. A very simple of such
joint coding can be an "exclusive or" operation on each bit of "d"
and "u". In this case, the length of "d" used in the coding is the
same as the length of "u". Consequently, the jointly coded bit
stream has the same length as the terminal's own uplink payload. If
the length of the uplink payload is known in advance, then a
downlink payload "d" of the correct length may be supplied.
Alternatively, or if a common downlink payload is used by two or
more terminals having uplink payloads of different lengths, the
downlink payload may be truncated or repeated to provide a bit
stream of the correct length. Alternatively, a more sophisticated
joint coding may be used and the resulted bit stream may be longer
than the mobile's own uplink payload.
[0027] At the base station's receiver, the uplink message is
decoded. The decoder takes account of the downlink transmitted bit
stream "d", which is of course already known to the decoder. The
decoder also uses the knowledge of the joint coding mechanism at
the terminal's transmitter, which is agreed in advance or specified
in the air-interface specifications. The decoding is then performed
in joint manner, where "d" also participates the decoding of
"u".
[0028] Many modifications and alterations of the methods and
systems described herein may be employed by those skilled in the
art without departing from the spirit and scope of the invention
which is limited only by the claims.
* * * * *