U.S. patent application number 17/007590 was filed with the patent office on 2021-02-04 for establishing wireless communication between a train and base stations.
The applicant listed for this patent is Swisscom AG. Invention is credited to Thomas Zasowski.
Application Number | 20210036742 17/007590 |
Document ID | / |
Family ID | 1000005150176 |
Filed Date | 2021-02-04 |
United States Patent
Application |
20210036742 |
Kind Code |
A1 |
Zasowski; Thomas |
February 4, 2021 |
ESTABLISHING WIRELESS COMMUNICATION BETWEEN A TRAIN AND BASE
STATIONS
Abstract
Methods and systems are provided for establishing wireless
communication between moving objects and land-based networks. A
plurality of virtual antenna arrays may be established for
communication between a transportation object and a communication
network. Each virtual antenna array includes antenna(s) of at least
one network transceiver of the communication network that is in
proximity to the transportation object or its path, and antenna(s)
of at least one transceiver from a plurality of transceivers in the
transportation object. Each virtual antenna array differs from an
adjacent virtual antenna array at least in having one or both of a
different network transceiver of the communication network or a
different transceiver from the plurality of transceivers.
Operations of the plurality of virtual antenna arrays may be
managed, with the managing including switching to an adjacent one
of the plurality of virtual antenna arrays based on movement of the
transportation object.
Inventors: |
Zasowski; Thomas; (Zurich,
CH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Swisscom AG |
Bern |
|
CH |
|
|
Family ID: |
1000005150176 |
Appl. No.: |
17/007590 |
Filed: |
August 31, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16356504 |
Mar 18, 2019 |
10763923 |
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17007590 |
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15412730 |
Jan 23, 2017 |
10236944 |
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16356504 |
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14153255 |
Jan 13, 2014 |
9554285 |
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15412730 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04B 7/0413 20130101;
H04W 4/40 20180201; H04W 4/023 20130101; H04W 48/20 20130101; H04B
7/15507 20130101; H04W 4/42 20180201; H04B 7/024 20130101; H04W
16/26 20130101; H04B 7/026 20130101 |
International
Class: |
H04B 7/026 20060101
H04B007/026; H04W 16/26 20060101 H04W016/26; H04W 4/42 20060101
H04W004/42; H04B 7/155 20060101 H04B007/155; H04W 48/20 20060101
H04W048/20; H04B 7/024 20060101 H04B007/024; H04B 7/0413 20060101
H04B007/0413; H04W 4/02 20060101 H04W004/02; H04W 4/40 20060101
H04W004/40 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 15, 2013 |
EP |
13000204.1 |
Claims
1-20. (canceled)
21. A method comprising: establishing a plurality of virtual
antenna arrays for communications between a transportation object
and a communication network, wherein: each virtual antenna array
comprises one or more antennas of at least one network transceiver
of the communication network that is in proximity to the
transportation object or a path of the transportation object, and
one or more antennas of at least one transceiver from a plurality
of transceivers in the transportation object; and each virtual
antenna array differs from an adjacent virtual antenna array at
least in having one or both of a different network transceiver of
the communication network or a different transceiver from the
plurality of transceivers; managing operations of the plurality of
virtual antenna arrays, wherein the managing comprises: using one
of the plurality of virtual antenna arrays to support
communications between one or more communication devices within the
transportation object and the communication network; and switching
from a virtual antenna array being used to an adjacent one of the
plurality of virtual antenna arrays based on movement of the
transportation object.
22. The method of claim 21, further comprising configuring the
communications based on one or more cooperative communication
schemes.
23. The method of claim 22, wherein the one or more cooperative
communication schemes comprise one or both of: use of spatial
diversity by concurrently transmitting a signal on multiple
communication channels; and use of spatial multiplexing by
transmitting different segments of the signal via different
communication channels.
24. The method of claim 21, further comprising controlling the
communications based on one or both of: information relating to the
movement of the transportation object; and information relating to
relative positions of the plurality of transceivers within the
transportation object.
25. The method of claim 24, further comprising generating
information relating to one or both of the movement of the
transportation object and to the relative positions of the
plurality of transceivers within the transportation object.
26. The method of claim 21, further comprising configuring the
communications based on channel related data associated with the
virtual antenna array.
27. The method of claim 26, further comprising determining the
channel related data for one of the plurality of virtual antenna
arrays, and re-using the channel related data for another one of
the plurality of virtual antenna arrays.
28. The method of claim 26, further comprising determining the
channel related data based on one or both of channel related
measurements in at least one network transceiver of the
communication network and channel related measurements in at least
one transceiver from the plurality of transceivers.
29. The method of claim 21, further comprising setting up multiple
communication channels for communicating via at least one of the
plurality of virtual antenna arrays.
30. The method of claim 29, further comprising communicating
concurrently via the multiple communication channels.
31. A system for use in a transportation object to provide wireless
communication, the system comprising: a plurality of transceivers;
and one or more communication circuits configured to: establish a
plurality of virtual antenna arrays for communications between the
transportation object and a communication network, wherein: each
virtual antenna array comprises one or more antennas of at least
one network transceiver of the communication network that is in
proximity to the transportation object or a path of the
transportation object, and one or more antennas of at least one
transceiver from the plurality of transceivers in the
transportation object; and each virtual antenna array differs from
an adjacent virtual antenna array at least in having one or both of
a different network transceiver of the communication network or a
different transceiver from the plurality of transceivers; manage
operations of the plurality of virtual antenna arrays, wherein the
managing comprises: using one of the plurality of virtual antenna
arrays to support communications between one or more communication
devices within the transportation object and the communication
network; and switching from a virtual antenna array being used to
an adjacent one of the plurality of virtual antenna arrays based on
movement of the transportation object.
32. The system of claim 31, wherein the one or more communication
circuits are configured to configure the communications based on
one or more cooperative communication schemes.
33. The system of claim 32, wherein the one or more communication
circuits are configured to, when configuring the communications
based on one or more cooperative communication schemes, incorporate
use of one or both of: use of spatial diversity by concurrently
transmitting a signal on multiple communication channels; and use
of spatial multiplexing by transmitting different segments of the
signal via different communication channels.
34. The system of claim 31, wherein the one or more communication
circuits are configured to control the communications based on one
or both of: information relating to the movement of the
transportation object; and information relating to relative
positions of the plurality of transceivers within the
transportation object.
35. The system of claim 34, wherein the one or more communication
circuits are configured to generate information relating to one or
both of the movement of the transportation object and to the
relative positions of the plurality of transceivers within the
transportation object.
36. The system of claim 31, wherein the one or more communication
circuits are configured to configure the communications based on
channel related data associated with the virtual antenna array.
37. The system of claim 36, wherein the one or more communication
circuits are configured to determine the channel related data for
one of the plurality of virtual antenna arrays, and re-using the
channel related data for another one of the plurality of virtual
antenna arrays.
38. The system of claim 36, wherein the one or more communication
circuits are configured to determine the channel related data based
on one or both of channel related measurements in at least one
network transceiver of the communication network and channel
related measurements in at least one transceiver from the plurality
of transceivers.
39. The system of claim 31, wherein the one or more communication
circuits are configured to set up multiple communication channels
for communicating via at least one of the plurality of virtual
antenna arrays.
40. The system of claim 39, wherein the one or more communication
circuits are configured to communicate concurrently via the
multiple communication channels.
Description
CLAIM OF PRIORITY
[0001] This patent application is a continuation of U.S. patent
application Ser. No. 16/356,504, filed on Mar. 18, 2019, which is a
continuation of U.S. patent application Ser. No. 15/412,730, filed
on Jan. 23, 2017, which is a continuation of U.S. patent
application Ser. No. 14/153,255, filed on Jan. 13, 2014, which
pursuant to 35 U.S.C. .sctn. 119 claims the filing date benefit of
and right of priority to European (EP) Patent Application Serial
No. 13000204.1, filed on Jan. 15, 2013. Each of above identified
applications is hereby incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of
communications. In this regard, various example embodiments of the
invention relate to a system and a method for establishing wireless
communication between a train and base stations. Specifically, the
present invention relates to a communication system and a
communication method for establishing wireless communication
between a train and one or more base stations of a mobile radio
network which are arranged along a track travelled by the train,
which may be, for example a high speed train.
BACKGROUND OF THE INVENTION
[0003] The wide spread use of mobile communication devices for
wireless data communication has made it a great challenge for
manufacturers and operators of telecommunications networks to
provide wireless data communication with sufficient bandwidth and
broadband capacity. In particular, communication related issues may
arise in transportation related use scenarios. For example, on
trains, where typically a large number of users attempt to use
broadband data communication services simultaneously through the
same limited number of base stations in reach of the train, it may
be very difficult to provide sufficient data communication capacity
for a passing train. Moreover, the tremendous increase of the speed
of trains has augmented this problem as data communication
resources need to be provided very quickly, with great bandwidth
and broadband capacity, and for very short periods of time.
[0004] Further limitations and disadvantages of conventional and
traditional approaches will become apparent to one of skill in the
art, through comparison of such systems with some aspects of the
present invention as set forth in the remainder of the present
application with reference to the drawings.
BRIEF SUMMARY OF THE INVENTION
[0005] A system and/or method is provided for establishing wireless
communication between a train and base stations, substantially as
shown in and/or described in connection with at least one of the
figures, or otherwise as described herein, as set forth more
completely in the claims.
[0006] These and other advantages, aspects and novel features of
the present invention, as well as details of an illustrated
embodiment thereof, will be more fully understood from the
following description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Various features and advantages of the invention will become
apparent from the following description of non-limiting exemplary
embodiments, with reference to the appended drawings, in which:
[0008] FIG. 1a is a block diagram illustrating schematically a top
view of a moving train including a number of coaches with
communication relays.
[0009] FIG. 1b is a block diagram illustrating schematically a side
view of a moving train and communication channels established
between a communication relay mounted on a first coach at the front
of the train and antennas of a stationary base station.
[0010] FIG. 1c is a block diagram illustrating schematically a side
view of a moving train, at a time where a second coach from the
front of the train is at the same position where a first coach at
the front of the train was previously.
[0011] FIG. 2 is a block diagram illustrating an example
configuration of a communication system for establishing wireless
communication between a train and a plurality of base stations
arranged along a track travelled by the train.
[0012] FIGS. 3a-3d illustrate schematically top views of a moving
train at different times where the train has advanced through a
particular position one coach at a time, such that corresponding
communication channels are established between stationary base
stations and the coaches that consecutively pass by the base
stations.
[0013] FIGS. 4a-4d illustrate schematically top views of a moving
train at different times where the train has advanced through a
particular position one coach at a time, such that corresponding
communication channels are established between antennas of a
stationary base station and antennas on coaches that consecutively
pass by the base station.
[0014] FIG. 5 is a flow diagram that illustrates an example
sequence of steps for establishing wireless communication between a
train and a plurality of base stations arranged along a track
travelled by the train.
[0015] FIG. 6 is a timing chart illustrating schematically the
change over time of the CSI of communication channels established
between a stationary base station and antennas of communication
relays on a train passing by the base station.
DETAILED DESCRIPTION OF THE INVENTION
[0016] As utilized herein the terms "circuits" and "circuitry"
refer to physical electronic components (e.g., hardware) and any
software and/or firmware ("code") which may configure the hardware,
be executed by the hardware, and or otherwise be associated with
the hardware. As used herein, for example, a particular processor
and memory may comprise a first "circuit" when executing a first
one or more lines of code and may comprise a second "circuit" when
executing a second one or more lines of code. As utilized herein,
"and/or" means any one or more of the items in the list joined by
"and/or". As an example, "x and/or y" means any element of the
three-element set {(x), (y), (x, y)}. In other words, "x and/or y"
means "one or both of x and y." As another example, "x, y, and/or
z" means any element of the seven-element set {(x), (y), (z), (x,
y), (x, z), (y, z), (x, y, z)}. In other words, "x, y and/or z"
means "one or more of x, y, and z." As utilized herein, the term
"exemplary" means serving as a non-limiting example, instance, or
illustration. As utilized herein, the terms "for example" and
"e.g.," set off lists of one or more non-limiting examples,
instances, or illustrations. As utilized herein, circuitry is
"operable" to perform a function whenever the circuitry comprises
the necessary hardware and code (if any is necessary) to perform
the function, regardless of whether performance of the function is
disabled or not enabled (e.g., by a user-configurable setting,
factory trim, etc.).
[0017] Certain example embodiments of the present disclosure may be
found in a method and a system for establishing wireless
communication between a train and base stations, as described in
the following in more detail with reference to the attached
figures. In particular, a communication system and a communication
method are provided for establishing wireless broadband data
communication between a moving train and base stations arranged
along the track travelled by the train.
[0018] In some example embodiments, establishing wireless
communication between a train and one or more base stations
arranged along a track travelled by the train may comprise setting
up communication channels between one or more antennas of
communication relays on the train and one or more antennas of the
base stations. Channel state information (CSI) may be determined
and stored in a data store, and the CSI may be used for
communicating via the communication channels, depending on
information defining the current location of the communication
relays. CSI is inherently location-specific and time-dependent. For
a given position in space CSI may change gradually over time. The
rate of change and thus the time over which a channel/CSI may be
considered essentially constant is a channel parameter which may be
referred to as the channel coherence time. Hence, over a certain
time interval given by the channel coherence time, a channel/CSI
may be considered constant for a specific point in space.
[0019] Using CSI in such embodiments may make it possible to reduce
processing time and signalling overhead required for measuring the
CSI, as the CSI may need to be determined only once in a certain
period of time--e.g., at a communication relay at the head of the
train, and can be reused by communication relays located further
back on the train--e.g., when they subsequently pass the respective
location(s) for which the CSI was measured earlier. Thus, the
implicit priori information about the layout of the train track(s)
and the moving direction of the train is used to determine the CSI
used for communicating via the communication channels.
[0020] The position of the train track(s) and the moving direction
of the train may be essentially deterministic, and all antennas of
a communication relay may observe essentially the same
communication channel at the same absolute position in space, over
a certain time period. For example, if communication relays or
antennas on the train are aligned in a row and spaced at 10 m from
each other, the second communication relay or antenna from the
front of the train may observe the same communication channel with
the same CSI as the first communication relay or antenna at the
front of the train, after the train has moved 10 m or after 10/v
seconds, if v is the speed in m/s, respectively. Consequently, the
CSI measured for the communication relay or antenna at the front of
the train in a moving direction may be propagated to the
communication relays or antennas arranged further back on the
train.
[0021] In some example embodiments, a multiple-input and
multiple-output (MIMO) array may be established and/or used. The
MIMO array may comprise at least two communication relays arranged
on the train and at one or more of the base stations. Communication
may be executed concurrently via multiple communication channels of
the MIMO array using cooperative communication schemes, where each
communication channel is set up between one of the communication
relays and one of the base stations included in the MIMO array.
Using MIMO arrays and cooperative communication schemes in the
non-static, dynamically changing environment of moving trains and
stationary base stations makes it possible to increase
communication bandwidth (capacity) and/or to improve the robustness
of signal transmission (reliability) by transmitting segments of a
signal via different communication channels of the MIMO array or by
transmitting concurrently an identical signal on multiple
communication channels of the MIMO array, for example.
[0022] In an example embodiment, the CSI may be determined by
performing a CSI measurement in the communication relay arranged in
a front position in a moving direction of the train or by
performing a CSI measurement in a base station associated with a
communication channel that includes the communication relay
arranged in the front position in the moving direction of the
train. Alternatively, the CSI may be retrieved from a database
associated with the track travelled by the train.
[0023] In an example embodiment, the CSI used for communicating
(e.g., via the communication channels of the MIMO array) may be
determined depending on information about the speed of the train
and information about relative positions of the communication
relays on the train.
[0024] In various example embodiments, one or more cooperative
communication schemes may be used for communicating via the
communication channels of the MIMO array. Example cooperative
communication schemes may comprise implementing spatial diversity
by transmitting concurrently an identical signal on all of the
communication channels of the MIMO array, and/or implementing
spatial multiplexing by transmitting segments of the signal via
different communication channels of the MIMO array.
[0025] In an example embodiment, the CSI, information about the
speed of the train, and/or information about relative positions of
the communication relays on the train may be transmitted from the
train to the base stations.
[0026] In an example embodiment, the communication relays may be
arranged on the train, such that the communication relays may
travel essentially through a same path in space when the train
travels on the track. For example, the communication relays are
arranged on top of the train, and are centred with respect to both
sides of the train, with one or more equally spaced communication
relays occurring per train coach.
[0027] In addition to a communication system and a communication
method for establishing wireless communication between a train and
one or more base stations arranged along a track travelled by the
train, the present disclosure also includes a computer program
product comprising a computer-readable storage medium having stored
thereon computer code which is configured to direct a processor
arranged on a train to perform the steps of setting up
communication channels between one or more antennas of
communication relays arranged on the train and one or more antennas
of base stations arranged along a track travelled by the train,
determining and storing CSI in a data store, and communicating via
the communication channels using the CSI for the communication
channels, depending on information defining the current location of
the communication relays.
[0028] FIG. 1a is a block diagram illustrating schematically a top
view of a moving train including a number of coaches with
communication relays. Referring to FIG. 1a, there is shown a train
2. The train 2 may comprise a high speed train, configured to move
at high speeds (e.g., speeds at or above 200 km/h). Nonetheless,
the disclosure is not exclusively limited to high speed trains.
[0029] The train 2 may comprise one or more locomotives L, which
may be coupled to one or more carts or coaches C1, C2, C3, C4, . .
. , Cn (short: C1-Cn). As shown in FIG. 1a (as well as in at least
some of the following figures), the train 2 may move for example in
a particular moving direction d, such as along a track 3--e.g., on
railways including a set of rails or a monorail, such as by way of
wheels and/or magnetic levitation.
[0030] The train 2 may incorporate components for use in enabling
and/or supporting communications--e.g., with base stations. For
example, as shown in FIG. 1a, the train 2 may incorporate a
plurality of communication relays R1, R2, R3, R4, R5, R6, R7, R8,
R9, Rm (short: R1-Rm). In this regard, each of the communication
relays R1-Rm may comprise suitable circuitry as well as one or more
antennas, for facilitating communication of signals to and/or from
the relays. The communication relays R1-Rm may be configured to
establish communication channels between the communication relays
R1-Rm and base stations (e.g., base stations near the track 3).
[0031] In some instances, the communication relays R1-Rm may be
interconnected, such as by way of a wired or wireless communication
link--e.g., through WLAN, Ethernet, power-line communication (PLC),
UMTS, LTE, etc.
[0032] The communication relays R1-Rm or their antennas,
respectively, may be arranged in a particular manner. For example,
communication relays R1-Rm or their antennas, respectively, may be
arranged with known respective (geometric) distance to each other.
In some instances, the individual communication relays R1-Rm or
defined subsets of the communication relays R1-Rm may be arranged
at equal distances to each other. The communication relays R1-Rm or
their antennas, respectively, may be arranged such that they travel
essentially through the same path in space (in all three
dimensions) when the train travels on the track 3 during a train
ride. For example, the communication relays R1-Rm are mounted at
the same height with respect to the tracks 3, on top of the train
2, one or more communication relays R1-Rm per coach or cart C1-Cn,
and centred with respect to both sides of the train 2, as
illustrated in the top view of FIG. 1a. In an example embodiment, a
further communication relay is installed on the locomotive(s)
L.
[0033] In various example embodiments, a communication system may
be arranged in/on the train 2, particularly to facilitate wireless
communication between devices within the train 2 and wireless
networks that may have access means (e.g., base stations) arranged
along the track 3 (e.g., base stations). An example of such
communication system is shown in, and described in more detail with
respect to, FIG. 2.
[0034] FIG. 2 is a block diagram illustrating an example
configuration of a communication system for establishing wireless
communication between a train and a plurality of base stations
arranged along a track travelled by the train. Referring to FIG. 2,
there is shown a communication system 1.
[0035] The communication system 1 may be arranged in/on a train
(e.g., the train 2). In this regard, the communication system 1 may
comprise suitable circuitry, and/or any other suitable
communication components, for establishing wireless connectivity
(and for facilitating wireless communication based thereon) between
the train and one or more base stations (e.g., base stations B1,
B2), which may be arranged along a track traversed by the train.
Accordingly, the communication system 1 may enable mobile
communication devices (e.g., mobile communication device 4) located
in the train to communicate via mobile radio networks, accessed via
the base stations, with other communication units.
[0036] Each of the base stations B1, B2 may comprise suitable
circuitry for providing base station functions, such as in a mobile
radio network 5. The mobile radio network 5 may comprise an LTE
(Long Term Evolution) or LTE-Advanced network, a GSM-network
(Global System for Mobile communication), a UMTS (Universal Mobile
Telephone System) network, or any another cellular telephone or
data network suitable for wireless communication. Further, each of
the base stations B1, B2 may comprise one or more antennas. The
mobile communication device 4 may comprise suitable circuitry, for
enabling and/or configuring the mobile communication device 4 to
communicate wirelessly--e.g., in the mobile radio network 5 via
base stations B1, B2. The mobile communication device 4 may
comprise a mobile telephone, a smart phone, a tablet or notebook
computer, a PDA (Personal Digital Assistant) type computer, or any
other suitable user carried or supported device.
[0037] For example, the communication system 1 may comprise several
communication relays (e.g., the communication relays R1-Rm), for
establishing communication channels between the communication
relays (R1-Rm) and the base stations B1, B2. The communication
system 1 may also comprise one or more operable computers,
including one or more processors, configured to establish wireless
communication between the train 2 and base stations B1, B2 arranged
along the track 3 travelled by the train 2, thereby enabling a
mobile communication device 4 located in the train 2 to communicate
via the mobile radio network 5 with other communication units.
Accordingly, where the mobile communication device 4 is located in
the train 2, communication via the mobile radio network 5 may be
enabled by the communication relays R1-Rm through communication
channels established with the base stations B1, B2.
[0038] In various example embodiments, the communication system 1
may comprise several functional modules, for supporting the
communication functions performed thereby. In accordance with some
example embodiments, the functional modules may be implemented (by
components and/or suitable circuitry of the communication system 1
may) as programmed software modules. Nonetheless, in alternative
example embodiments, one or more of the functional modules may be
implemented fully or partly by way of dedicated hardware
components. For example, communication system 1 may comprise at
least one communication unit 10, at least one channel estimator 11,
and at least one data store 12. The data store 12 may comprises
data storage devices or modules for storing data. The computer
program code of the software modules is included in a computer
program product--e.g., stored on a computer readable medium, either
in memory integrated in a computer of the communication system 1 or
on a tangible data carrier, which can be inserted into or connected
to a computer of the communication system 1. The computer program
code of the software modules controls the computer(s) or
processor(s), respectively, of the communication system 1 so that
the computer of the communication system 1 executes various
functions described below in more detail.
[0039] The communication unit 10 may connected to the communication
relays R1-Rm via wired or wireless communication links--e.g.,
through WLAN, Ethernet, power-line communication (PLC), UMTS, LTE,
etc. In one example embodiment, the communication unit 10 may be
implemented as a cooperative communication unit, which may be
configured to establish a virtual multiple-input and
multiple-output (MIMO) array. For example, such virtual MIMO array
may comprise antennas of at least two of the communication relays
R1-Rm, and one or more of the base stations B1, B2.
[0040] The channel estimator 11 may be configured to determine
and/or store, such as in the data store 12, (location-specific)
channel state information (CSI). The CSI may relate to various
channel properties of communication channels (e.g., communication
channels between the communication relays R1-Rm and the base
stations B1, B2). For example, the CSI may describe how a signal
propagates via the respective communication channel from a
transmitter to a receiver and represents the combined effect of,
for example, scattering, fading, and power decay with distance. The
CSI for a communication channel between a communication relay R1-Rm
and a base station B1, B2 may be location-specific in that it may
indicate the channel properties of the communication channel for a
given location of the respective communication relay R1-Rm--e.g., a
given location along the track 3 travelled by the train 2, defining
a position or location with regards to the base station B1, B2. The
CSI may make it possible to adapt transmissions to current and/or
estimated future channel conditions. Because the communication
relays R1-Rm or their antennas, respectively, are arranged on the
train 2 to travel through the same path in space, for any location
on that path, the same CSI can be used for communication channels
established between a communication relay R1-Rm at that respective
location and a base station B1, B2 along the tracks 3. Example use
scenarios of the communication system 1 with respect to the train 2
(as shown in FIG. 1a) are described in more detail with respect to
FIGS. 1b and 1c.
[0041] FIG. 1b is a block diagram illustrating schematically a side
view of a moving train and communication channels established
between a communication relay mounted on a first coach at the front
of the train and antennas of a stationary base station. Referring
to FIG. 1b, there is shown a side view of the train 2 (as described
with respect to FIG. 1a) as it moves along the track 3, passing by
the base station B1.
[0042] Also shown in the particular scenario depicted in FIG. 1b
are four communication channels h11, h21, h31, h41, which may be
established between the antennas of base station B1 and
communication relay R1 of the first coach C1, when the front of the
first coach C1 at the front of the train 2 is at position X.
Accordingly, in this scenario, the CSI describes the channel
properties of each of these communication channels h11, h21, h31,
h41.
[0043] FIG. 1c is a block diagram illustrating schematically a side
view of a moving train, at a time where a second coach from the
front of the train is at the same position where a first coach at
the front of the train was previously. Referring to FIG. 1b, there
is shown a side view of the train 2 (as described with respect to
FIG. 1a) as it moves along the track 3, passing by the base station
B1.
[0044] In the particular scenario shown in FIG. 1c, the train 2
would have moved in a moving direction d with respect to the
position of the train 2 shown in FIG. 1b by a distance of one coach
or cart C1-Cn--i.e., at the time depicted in FIG. 1c, the second
coach C2 from the front of the train 2 is at the same position X as
the first coach C1 at the front of the train 2, at the time of the
snap shot depicted in FIG. 1b. Consequently, at the position X of
the train 2 shown in FIG. 1c, the CSI of the communication channels
h13, h23, h33, h43 between the antennas of base station B1 and the
antennas of communication relay R3 may correspond to the CSI of the
communication channels h11, h21, h31, h41 between the antennas of
base station B1 and the antennas of communication relay R3, at the
position of the train 2 shown in FIG. 1b for some period of time,
which is sometimes referred to as channel coherence time.
[0045] Accordingly, CSI determined for a communication channel(s)
established through a communication relay R1 at the front of the
train 2 at a position X may be used for communication channels
established through communication relays R2-Rm farther back in the
train 2 when these rear communication relays R2-Rm pass through the
same position X. The time or position when the measured and/or
estimated (location-specific) CSI applies to a rear communication
relay R2-Rm on the train 2 depends on information defining the
current location of these communication relays R2-Rm. For example,
the current location of the communication relays R2-Rm may be
defined by information defining the position of the communication
relays R1-Rm relative to each other--e.g., the relative distance,
and the speed of the train 2.
[0046] Referring back to FIG. 2, the channel estimator 11 may be
configured to determine the CSI for communication channels h11,
h21, h31, h41, such as by performing a CSI measurement in the
communication relay R1 arranged in front position in moving
direction d of the train 2. Alternatively, the CSI may be measured
by a base station (e.g., one of the base stations B1, B2), with the
channel estimator 11 receiving the CSI from the base station. For
example, the CSI may be measured by the base station B1 included in
the communication channel h11, h21, h31, h41 with the communication
relay R1 arranged in front position of the train 2, and the channel
estimator 11 may receive the CSI from the base station B1. The CSI
measurement may be performed at the communication relay (e.g.,
communication relay R1) or respective base station (e.g., based
station B1) using known measurement methods. For example, the CSI
measurement may be performed by transmitting a known signal, a
so-called training or pilot sequence, and estimating the CSI using
the combined knowledge of the transmitted and received signal. In
an example embodiment, where the CSI is determined through
measurements in a communication relay of the train (e.g.,
communication relay R1), the channel estimator 11 may be further
configured to transmit the determined CSI to the respective base
station(s) (e.g., one or both of the base stations B1, B2) and/or
other communication relays (e.g., the rear communication relays
R2-Rm).
[0047] The communication unit 10 may connected to the communication
relays R1-Rm via wired or wireless communication links--e.g.,
through WLAN, Ethernet, power-line communication (PLC), UMTS, LTE,
etc. In one example embodiment, the communication unit 10 may be
implemented as a cooperative communication unit, which may be
configured to establish a virtual multiple-input and
multiple-output (MIMO) array. For example, such virtual MIMO array
may comprise antennas of at least two of the communication relays
R1-Rm, and one or more of the base stations B1, B2.
[0048] FIGS. 3a-3d illustrate schematically top views of a moving
train at different times where the train has advanced through a
particular position one coach at a time, such that corresponding
communication channels are established between stationary base
stations and the coaches that consecutively pass by the base
stations. Referring to FIGS. 3a-3d, there are shown top views of
the train 2 (as described with respect to FIGS. 1a and 2) as it
moves along the track 3, passing by the base stations B1, B2.
[0049] In the example scenarios depicted in FIGS. 3a-3d, time snap
shots are shown of the train 2 at times T1, T2, T3, and T4 (short
T1-T4), as the train 2 advances in moving direction d, by
particular distance, such as by length (lc) of one coach or cart
C1-Cn. Accordingly, depending on speed (v) of the train 2 and the
length lc of a cart C1-Cn, a duration of time (Ti) between
consecutive points in time T1-T4 may be defined by Ti=lc/v.
Assuming a constant speed v of the train 2 (as well as similar cart
length lc for all coaches C1-Cn), the points in time T1-T4 may be
at regular intervals Ti=T4-T3=T3-T2=T2-T1. Thus, in the duration of
time Ti for example, the train 2 may move forward such that, at
time t, a second cart C2 takes the place that a first cart C1,
arranged adjacent in front of the second cart C2, would have
occupied at the time t-Ti, whereby, at the time t, the
communication relays R3, R4 or antennas of the second cart C2 may
be at the same position as the communication relays R1-R2 or
antennas of the first cart C1 were before, at time t-T1.
[0050] Further, the communication system 1 arranged on and/or in
the train 2 may be configured to established (e.g., via the
communication unit 10) different (virtual) MIMO arrays. In this
regard, referring to the example scenarios shown in FIGS. 3a-3d,
different example (virtual) MIMO arrays M1, M2, M3, M4 (short:
M1-M4) may be established, comprising in each case antennas of the
base stations B1 and B2, as well as antennas of one or more
communication relays (e.g., four or three of the communication
relays R2-Rm). For example, the MIMO arrays M1-M4 may be configured
as outlined in Table 1:
TABLE-US-00001 TABLE 1 example configurations for MIMO arrays M1-M4
B1 B2 MIMO M1 R2 h1a h2a R3 h1b h2b R4 h1c h2c R5 h1d h2d MIMO M2
R4 h1a h2a R5 h1b h2b R6 h1c h2c R7 h1d h2d MIMO M3 R6 h1a h2a R7
h1b h2b R8 h1c h2c R9 h1d h2d MIMO M4 R8 h1a h2a R9 h1b h2b Rm h1c
h2c -- -- --
[0051] In this regard, in the example scenarios depicted in FIGS.
3a-3d, at each of the points in time T1-T4, the MIMO arrays M1-M4
may be established between the base stations B1, B2 and, for
example, four (or three) communication relays {R2, R3, R4, R5},
{R4, R5, R6, R7}, {R6, R7, R8, R9}, {R8, R9, Rm}. As the subsets of
communication relays {R2, R3, R4, R5}, {R4, R5, R6, R7}, {R6, R7,
R8, R9}, {R8, R9, Rm} included in the MIMO arrays M1-M4 are in the
same absolute positions (assuming constant speed and cart length),
communication channels h1a, h1b, h1c, h1d, h2a, h2b, h2c, h2d
(short: h1a-h2d) established between the communication relays {R2,
R3, R4, R5}, {R4, R5, R6, R7}, {R6, R7, R8, R9}, {R8, R9, Rm} and
the base stations B1, B2 in the MIMO arrays M1-M4 may be
essentially the same. Accordingly, CSI of the communication channel
h1a, for example, established at T1 between the base station B1 and
communication relay R2 may correspond essentially to CSI of the
communication channel h1a established at T2, T3, or T4 between the
base station B1 and the communication relays R4, R6, or R8,
respectively. Nonetheless, CSI may exhibit temporal changes between
points in time T1-T4. Examples of continuous temporal changes of
the CSI for different channels (e.g., channels established via MIMO
arrays M1-M4), for a time window (e.g., time window of t=T1 to
t=T4), are shown in, and described in more detail with respect to,
FIG. 6.
[0052] In some instances, the communication system 1 may be
configured or implemented to use cooperative communications. In
this regard, the communication unit 10 may be configured as a
cooperative communication unit, and as such may be operable to
communicate concurrently via multiple communication channels, such
channels established via MIMO arrays (e.g., the communication
channels h1a-h2d of the MIMO array M1-M4), such as by use of
cooperative communication schemes. For example, in various example
embodiments (and/or configurations based thereon), the
communication unit 10 may be configured to use and/or implement as
cooperative communication scheme, spatial diversity, by
transmitting concurrently an identical signal on all the
communication channels h1a-h2d of the MIMO array M1-M4, or spatial
multiplexing, by transmitting segments of the signal via different
communication channels h1a-h2d of the MIMO array M1-M4. The
disclosure is not so limited, however, and other cooperative
communication schemes may be applicable and used in a substantially
similar manner.
[0053] FIGS. 4a-4d illustrate schematically top views of a moving
train at different times where the train has advanced through a
particular position one coach at a time, such that corresponding
communication channels are established between antennas of a
stationary base station and antennas on coaches that consecutively
pass by the base station. Referring to FIGS. 4a-4d, there are shown
top views of the train 2 (as described with respect to FIGS. 1a and
2) as it moves along the track 3, passing by the base stations B1,
B2.
[0054] In the example scenarios depicted in FIGS. 4a-4d, time snap
shots are shown of the train 2 at the T1-T4, substantially as
described with respect to FIGS. 3a-3d. In the example scenario
depicted in FIGS. 4a-4b, however, establishing connectivity with
the base stations does not entail configuring MIMO arrays. Rather,
in the example scenarios depicted in FIGS. 4a-4d, communication
channels h11, h21, h31, h41 may be set up between one or more
antennas (e.g., four) of a communication relay (e.g., one of the
communication relay R2, R4, R6, R8) and one or more antennas (e.g.,
four) of a particular base station (e.g., the base station B1) when
the train 2 advances in moving direction d by the length lc of one
coach or cart C1-Cn.
[0055] Accordingly, and assuming again a constant speed v of the
train 2 as well as similar cart length lc for all coaches C1-Cn,
the same CSI may apply to all of the communication channels h11,
h21, h31, h41. Specifically, the CSI of the communication channels
h11, h21, h31, h41, for example, established at T1 between the base
station B1 and communication relay R2 corresponds to the CSI of the
communication channels, h11, h21, h31, h41 established at T2, T3,
or T4 between the base station B1 and the communication relays R4,
R6, or R8, respectively.
[0056] In some instances, the communication unit 10 of the
communication system 1 may be configured to use corresponding CSI
for communicating via the one or more communication channels h11,
h21, h31, h41 between a communication relay R2, R4, R6, R8 and the
same particular base station B1 when the respective communication
relays R2, R4, R6, R8 have the same relative position with respect
to that particular base station B1 at times T1, T2, T3, T4. Thus,
without using any cooperative communication schemes, the
communication unit 10 may use the same CSI for the communication
channels h11, h21, h31, h41 established between the same base
station B1 and different communication relays R2, R4, R6, R8.
[0057] In some instances, in order to communicate via the
communication channels h11, h21, h31, h41 between the antennas of
communication relays R1-Rm and base stations B1, B2 and/or for
using cooperative communication schemes for multiple communication
channels h1a-h2c of one of the MIMO arrays M1-M4, the base stations
B1, B2, and communication relays R1-Rm may require the CSI of all
the communication channels h11, h21, h31, h41, and h1a-h2d between
the transceivers involved in the communication--i.e. the
communication channels h11, h21, h31, h41, and h1a-h2d, established
in each case between an antenna of one of the base stations B1, B2
and an antenna of one of the communication relays R1-Rm.
Accordingly, in some example embodiments, the (cooperative)
communication unit 10 and/or the base stations B1, B2 may be
configured to exchange the respective CSI.
[0058] In some example embodiments, the communication unit 10 may
be configured to transmit to the base stations B1, B2 information
about the current speed of the train 2 and the relative positions
of the communication relays R1-Rm.
[0059] In some example embodiments, there may be one or more than
one communication unit 10 arranged in the train 2. For example,
there may be one unit (of the communication unit 10) per cart
C1-Cn, one unit per logical group of communication relays R1-Rm
(e.g., the communication relays R1-Rm of two adjacent carts C1-Cn),
or one unit per communication relay R1-Rm. If instances where there
may be multiple communication units 10, these units may be
configured to cooperate and communicate with one another--e.g., via
wireless or wired communication channels--e.g., through WLAN,
Ethernet, power-line communication (PLC), UMTS, LTE, etc. Likewise,
the base stations B1, B2 may be controlled by one central
processing unit, one processing unit per logical group of base
stations B1, B2, or one processing unit per base station B1, B2,
whereby in the case of multiple processing units, they are
preferably interconnected to improve the overall system
performance.
[0060] FIG. 5 is a flow diagram that illustrates an example
sequence of steps for establishing wireless communication between a
train and a plurality of base stations arranged along a track
travelled by the train.
[0061] Referring to FIG. 5, there is shown sequence of example
steps that may be performed (e.g., in a communication system, such
as the communication system 1 or functional modules thereof) for
establishing wireless communication between a train (e.g., the
train 2) and a plurality of base stations (e.g., the base stations
B1, B2) arranged along a track travelled by the train (e.g., the
track 3 travelled by the train 2).
[0062] In example step S1, channel information (e.g., CSI), which
may be location-specific, may be determined and stored (e.g., by
the channel estimator 11). For example, the channel estimator 11
may determine and store CSI for the communication channels set up
by the communication relay R1 at the front of the train 2 using
real-time CSI measurements, which may be performed by the
communication relay R1 at the front of the train 2 or by the base
stations B1, B2 included in the communication channels set up by
the communication relay R1 at the front of the train 2. In other
instances, however, the channel estimator 11 may obtain from a CSI
database (e.g., pre-measured, historic) CSI for the track 3 or a
section of the track 3. The CSI database may be maintained in a
centralized manner (e.g., stored in a centralized computer system
remote from the train 2), or in localized manner (e.g., in a local
database or lookup table on the train 2).
[0063] In example step S2, communication channels may be
established, which may comprise establishing connectivity as well
as (in some instances) configuring communication setups needed
therefor. For example, in the scenario(s) depicted in FIGS. 3a-3d,
the communication unit 10 may configure MIMO arrays (M1-M4) for
cooperative communication through a plurality of channels. In this
regard, the MIMO arrays M1-M4 may be established using antennas in
the base stations B1 and B2 and the communication relays R2-Rm when
they pass these base stations B1, B2. Nonetheless, in some
instances, the communication unit 10 may establish concurrently
multiple MIMO arrays between the communication relays R1-Rm of the
train 2 and the plurality of base stations B1, B2 arranged along
the track 3 travelled by the train 2 and within communication
range--e.g., within communication range of a defined minimum
communication quality. For the scenario(s) depicted in FIGS. 4a-4d,
the communication unit 10 may neither establish MIMO arrays, nor
use cooperative communication schemes. Rather, the communication
unit 10 may merely set up communication channels--e.g.,
communication channels h11, h21, h31, h41 between the antennas of a
base station B1 and the antennas of communication relays R2, R4,
R6, R8 on the cart C1, C2, C3, C4 passing the respective base
station B1.
[0064] In example step S3, channel related information for
established communication channels may be determined. For example,
in the scenario(s) depicted in FIGS. 3a-3d, the channel estimator
11 may determine CSI for the communication channels h1a-h2c of the
established MIMO arrays M1-M4. For the scenario(s) depicted in
FIGS. 4a-4d, the channel estimator 11 may determine CSI for the
communication channels h11, h21, h31, h41 set up between the
antennas of a base station B1 and the antennas of the communication
relay R2, R4, R6, R8 arranged on a cart C1, C2, C3, C4 passing the
respective base station B1. Using stored CSI (e.g., the CSI
determined and stored in example step S1), the CSI for the
communication channels h11, h21, h31, h41, and h1a-h2d may be
determined based on the location or position of the communication
relay R2-Rm included in the respective communication channel h11,
h21, h31, h41, and h1a-h2d. In this regard, the location or
position of the communication relays R2-Rm may be defined by their
relative arrangement on the train 2--e.g., their distance from the
communication relay R1 at the front of the train 2 in moving
direction d, and the speed of the train 2. Various mechanisms may
be used in propagating the CSI measured, in example step S1, at the
front of the train 2, from the communication relay R1 to the
communication relays R2-Rm further back on the train 2. For
example, in some example embodiments the CSI may be propagated
through data pulling or pushing functions, which may be performed
by channel estimator 11 that may arranged in the communication
relay R1 at the front of the train 2 (e.g., configured to perform
data pushing), in a centralized communication unit 10 of the train
(e.g., configured to perform data pushing and/or pulling), or in
the communication relays R2-Rm located further back on the train 2
(e.g., configured to perform data pulling).
[0065] In some example embodiments, where the CSI may be retrieved
from a CSI database, the location of the communication relays R1-Rm
may be determined further based on the current location of the
train 2 as provided by a positioning system, such as GPS (Global
Positioning System), or the mobile radio network 5.
[0066] In example step S4, communication may be performed (e.g., as
multi-channel communications). For example, the communication unit
10 may use the CSI determined for the communication channels h11,
h21, h31, h41 and/or the communication channels h1a-h2d, or for the
communication relays R1-Rm, respectively, for communicating through
the communication channels. Further, in some instances, the
communication may comprise additional operations. For example, for
the scenario(s) depicted in FIGS. 3a-3d, cooperative communication
may be performed through the communication channels of the MIMO
arrays M1-M4.
[0067] The process may then loop back (as indicated by P in FIG.
5), such that the processing may continue--e.g., continuously or
periodically repeating example steps S1 to S4, or in some instances
only repeating example steps S2 to S4 (e.g., depending on whether
CSI is determined in example step S1 through real-time measurements
or retrieval of stored CSI from a CSI database or lookup
table).
[0068] FIG. 6 is a timing chart illustrating schematically the
change over time of the CSI of communication channels established
between a stationary base station and antennas of communication
relays on a train passing by the base station.
[0069] Referring to FIG. 6, there is a shown a timing chart
depicting, for a time window (e.g., time window t=T1 to t=T4), the
continuous temporal change of CSI for a one or more communication
channels between a train and a base station--e.g., CSI: C12, C13,
C14, C15, C16, C17, C18, C19, C1m (or C12-C1m for short), for
communication channels established between the communication relays
R2-Rm and base station B1, as the train 2, and thus the
communication relays R2-Rm, pass by the base station B1 on the same
path. In the example timing chart shown in FIG. 6, the references
h1a, h1b, h1c, h1d indicate schematically that at the points in
time T1, T2, T3, T4, the CSI C12-C1m corresponds to the CSI of the
communication channels h1a, h1b, h1c, h1d as illustrated in the
corresponding snap shots of FIGS. 3a-3d. As is shown in FIG. 6, the
same CSI C12-C1m may be used for the communication channels
established between a communication relay R1-Rm and base station
B1, but shifted in time (e.g., as determined by the speed of the
train 2 and the distance between the communication relays
R1-Rm).
[0070] Other embodiments of the invention may provide a
non-transitory computer readable medium and/or storage medium,
and/or a non-transitory machine readable medium and/or storage
medium, having stored thereon, a machine code and/or a computer
program having at least one code section executable by a machine
and/or a computer, thereby causing the machine and/or computer to
perform the steps as described herein.
[0071] Accordingly, the present invention may be realized in
hardware, software, or a combination of hardware and software. The
present invention may be realized in a centralized fashion in at
least one computer system, or in a distributed fashion where
different units are spread across several interconnected computer
systems. Any kind of computer system or other apparatus adapted for
carrying out the methods described herein is suited. A typical
combination of hardware and software may be a general-purpose
computer system with a computer program that, when being loaded and
executed, controls the computer system such that it carries out the
methods described herein.
[0072] The present invention may also be embedded in a computer
program product, which comprises all the features enabling the
implementation of the methods described herein, and which when
loaded in a computer system is able to carry out these methods.
Computer program in the present context means any expression, in
any language, code or notation, of a set of instructions intended
to cause a system having an information processing capability to
perform a particular function either directly or after either or
both of the following: a) conversion to another language, code or
notation; b) reproduction in a different material form.
[0073] While the present invention has been described with
reference to certain embodiments, it will be understood by those
skilled in the art that various changes may be made and equivalents
may be substituted without departing from the scope of the present
invention. In addition, many modifications may be made to adapt a
particular situation or material to the teachings of the present
invention without departing from its scope. Therefore, it is
intended that the present invention not be limited to the
particular embodiment disclosed, but that the present invention
will include all embodiments falling within the scope of the
appended claims.
* * * * *