Machine Type Communications in a Radio Network
Field of the Invention
The invention relates to the field of telecommunications, and, more specifically,
to methods and devices for performing Machine Type Communications (MTC)
in a radio network.
Background
This section introduces aspects that may be helpful in facilitating a better
understanding of the invention. Accordingly, the statements of this section are
to be read in this light and are not to be understood as admissions about what is
in the prior art or what is not in the prior art.
Beside human activated services (e.g. voice and ftp/http data transfer) in radio
communication networks, a new form of communication, the so called Machine
Type Communication (MTC) is investigated to be integrated into radio
communication networks (such as UMTS, LTE, etc.). However, the design of
present radio communication networks is not preferably designed for machine
devices, e.g. sensors or actuators, acting in MTC. Thus, there are several
challenges to provide an efficient Machine to Machine (M2M) communication in
a settled (legacy) radio network.
For instance, from the point of view of the machine device, it is desired to have
algorithms that provide energy efficient working, regarding e.g. limited battery
capacity of cheap or small machine devices such as sensors. The challenge
from the network point of view is how to handle the large number of machine
devices (sensors etc.) spread in a cell of the radio access network. The
objective is not to overload the network, efficiently use Radio network resources
for M2M communications and also not to harm legacy services (e.g. voice).
Summary
The present invention is directed to addressing the effects of one or more of the
problems set forth above. The following presents a simplified summary of the
invention in order to provide a basic understanding of some aspects of the
invention. This summary is not an exhaustive overview of the invention. It is not
intended to identify key or critical elements of the invention or to delineate the
scope of the invention. Its sole purpose is to present some concepts in a
simplified form as a prelude to the more detailed description that is discussed
later.
One aspect of the invention relates to a method for providing information from a
machine device, in particular from a sensor device, to a radio access network,
the method comprising: transmitting, by the machine device, a plurality of
Random Access Channel preambles over a Random Access Channel, the
information being encoded by transmitting the Random Access Channel
preambles with pre-selected frequency offsets relative to each other.
A Random Access Channel (RACH) is generally used by wireless devices to get
the attention of a base station in order to initially synchronize its transmission
with the base station. The RACH is a shared channel that is used by a plurality
of wireless devices, and the signals (Random Access Channel preambles)
transmitted on the RACH are not scheduled, such that collisions between
RACH preambles of different wireless devices may occur.
The base stations of radio access networks, .e.g. eNB implementations in LTE,
have to recognize data transmitted from user equipments on the Random
Access Channel (RACH) which move with speeds of up to 500 km/h. The speed
of the user equipments leads to a Doppler shift of the received Random Access
Channel preambles of the RACH which has to be taken into account for
decoding. Therefore, a base station typically has a means for decoding signals
received with a Doppler shift, i.e. with a deviation (frequency offset) from the
nominal frequency of the RACH in the order of typically several hundred Hz.
The inventors propose to use the possibility of synchronic decoding of RACH
preambles with different frequencies which is already available in the base
station / radio access network in order to provide information to the RAN. For
this purpose, a plurality of RACH preambles is transmitted by one and the same
machine device, the information being encoded by using pre-defined frequency
offsets between the RACH preambles which may be recognized by the base
station / radio access network. For instance, a machine-specific sequence of
frequency offsets, or machine-specific frequency offsets may be chosen for
each (or a group of) machine devices, allowing at least to identify the machine
device(s) in the radio access network based on the pre-selected frequency
offsets. The term "pre-selected" refers to the fact that typically the base station /
RAN has knowledge about the specific frequency offsets / sequences of
frequency offsets of the mobile devices which may transmit on the RACH. In the
way described above, cost and energy efficient transfer of information from
machine devices to the radio access network / base station may be performed.
In one variant, the information is also encoded by transmitting the Random
Access Channel preambles with pre-selected timing offsets relative to each
other. In this example, a time sequence of RACH preambles is transmitted with
different frequency offsets and typically one pre-defined time offset between
subsequent RACH preambles. In this way, a frequency offset hopping pattern
may be provided, using both the time and frequency dimension to provide
information over the RACH to the Radio Access Network. A specific frequency
offset hopping pattern may be defined for each mobile device, allowing the base
station / RAN to identify the machine device.
In an alternative variant, at least two, preferably all Random Access Channel
preambles are transmitted at the same point of time. In this variant, the
possibility of synchronic decoding of several RACH preambles at the same
point of time can be advantageously used for increasing the amount of
information which can be transmitted on the RACH.
In another variant, the information is also encoded using the content of the
Random Access Channel preambles, in particular their sequence numbers. By
making a selection of the sequence numbers of the RACH preambles, a further
dimension of encoding may be provided which allows provisioning an additional
amount of information to the radio access network. The selection of the content
of the RACH preambles may be used concurrently with the use of frequency
offsets and possibly also timing offsets, optionally providing a frequency, time
and coding dimension for the transmitted information.
In a further variant, at least one of the frequency offsets, the timing offsets, and
the content of the Random Access Channel preambles is pre-configured in the
machine device upon installation of the machine device. Pre-configuring the
machine device with the frequency offsets and/or RAN specific parameters
during installation is particularly advantageous, as the machine device need not
communicate with the RAN for receiving the pre-defined frequency offsets.
However, especially with machine devices which move between different
locations of the RAN, it may be desirable to modify / update the pre-selected
frequency offsets by explicit messages from the RAN to the machine devices.
The proposed idea is most efficient when the speed of the machine device is
known in a receiving device in the RAN. In this case, the respective Doppler
shift (frequency offset) of the received radio signal is known beforehand and
can be used as a basis for the first point of the proposed frequency offset (and
possibly time offset) hopping pattern.
In another variant, the encoded information comprises identification information
for identifying the machine device and/or status information for informing the
radio access network about a status of the machine device. When the machine
device is a sensor device which only observes if a single quantity, e.g.
temperature, stress, etc. is in a pre-defined range, a RACH preamble sequence
may only be sent by the sensor device as soon as the measured quantity is out
of the specific range. In this case, the transmission of the RACH preambles by
the sensor device is already a status information indicating that there is a
problem with the quantity being observed by the sensor device.
In a further variant, the Random Access Channel preambles are transmitted
using a power level which is selected based on a power level of a previous
successful communication between the machine device and the radio access
network over the Random Access Channel. As indicated above, the RAN
connection is guaranteed through the RACH procedure (random access), using
uplink transmissions with increasing power levels. Thus, the RACH procedure
may have different power ramp up steps until a successful set-up of the RACH
procedure is achieved, i.e. the RAN is capable of decoding the RACH
preamble(s).
The last power ramp up level of a successful RACH procedure may be stored in
the machine device. For the next network RACH procedure, either the stored
power ramp up level or e.g. the power ramp up level one step below the stored
level may be used, thus reducing the number of steps and consequently the
power consumption of the RACH procedure. This approach is most efficient if
used for stationary (non-mobility) sensors (e.g. sensors attached to a bridge or
at defined traffic points for reporting traffic, etc.)
A further aspect of the invention relates to a (machine) device, in particular to a
sensor device, comprising: a transmission unit adapted for transmitting a
plurality of Random Access Channel preambles over a Random Access
Channel to a radio access network, and an encoding unit for encoding
information to be provided to the radio access network over the Random
Access Channel, the encoding unit being adapted to encode the information by
(pre-)selecting frequency offsets between the Random Access Channel
preambles to be transmitted by the transmission unit.
One skilled in the art will appreciate that although typically the (machine) device
typically provides low functionality, is cheap and should not consume much
energy, other devices, e.g. wireless mobile terminals used for interaction with
users (user equipments), may be provided with the additional functionality to
use the Random Access Channel for the transfer of information to the RAN.
In one embodiment, the encoding unit is further adapted to select timing offsets
between the Random Access Channel preambles for encoding the information.
In addition to the frequency offsets, timing offsets may be provided between the
RACH preambles, allowing to use a time and frequency pattern for transmitting
the information to the RAN. Although the same timing offset may be used for all
preambles of the RACH preamble sequence, it may also be possible to modify
the timing offset between subsequent preambles of the sequence, providing an
additional degree of freedom for the encoding.
In another embodiment, the encoding unit is further adapted to select the
content of the Random Access Channel preambles, in particular their sequence
numbers, for encoding the information. The information to be provided may also
be encoded using the content of the RACH preambles. By using this additional
degree of freedom for the encoding, the number of RACH preambles required
for transmitting a specific amount of information may be reduced, avoiding to
overload the Random Access Channel by efficient use of Radio network
resources.
In another embodiment, the machine device is adapted to use pre-configured
network configuration parameters, in particular pre-configured higher layer
parameters, of the radio access network for communication over the Random
Access Channel. For an energy efficient sensor node implementation, a
network pre-configuration may be uploaded on site during the first setup
(installation) of the sensor in the field. For this purpose, higher layer
parameters, i.e. parameters from layers above the physical layer, such as
network and cell specific layer 2 and layer 3 parameters, are read from system
information of the RAN and are uploaded to the machine device, typically during
installation of the machine device (in the field). Layer 2 and layer 3 procedure
parameters may then be stored in the machine device and may either be used
for its entire life-time or until the next update period (e.g. in case of a relevant
network parameter change). In this way, there is no need for a complete layer 2
and layer 3 hardware and/or software integration in the machine device.
A further aspect relates to a machine network comprising a plurality of machine
devices of the type described above, the machine network further comprising: a
master machine device adapted to receive network configuration parameters
from the radio access network, and to distribute the network configuration
parameters to the plurality of machine devices for updating pre-configured
network parameters, in particular higher layer parameters, used in the machine
devices for communication with the radio access network over the Random
Access Channel. Such a machine network is particularly advantageous in order
to avoid power-consuming wireless communications of the machine devices
with the RAN.
In the machine network, the master machine device is used for receiving the
network configuration parameters from the radio access network and to
distribute the parameters to the other machine devices, which may be
connected to the master machine device e.g. via cabling or possibly using
short-range wireless communications such as ZigBee, Bluetooth, etc. having
comparatively low power consumption.
Yet another aspect relates to a receiving device, in particular to base station, for
communicating over a Random Access channel with at least one machine
device as described above, the receiving device being adapted to decode the
information encoded in the frequency offsets and preferably in the timing offsets
between the Random Access Channel preambles and/or the contents of the
Random Access Channel preambles transmitted by the at least one machine
device. Using the receiving device, based on the decoded information, a
specific machine device may be identified and additional information, e.g. about
the status of the machine device, may be obtained by the RAN.
In one embodiment, the receiving device is adapted to identify the machine
device by comparing the decoded information with stored information about preconflgured
frequency offsets and preferably pre-configured timing offsets
between the Radio Access Channel preambles and/or the contents of the Radio
Access Channel preambles transmitted by a plurality of different machine
devices.
When using e.g. a time and frequency coding, a grid with fixed frequency and
timing offsets for the RACH preambles of all the machine devices may be
defined in the RAN. For each machine device, a pre-selected, preferably unique
selection of points in the time / frequency grid (frequency hopping pattern) may
be chosen and stored in the receiving device or elsewhere in the RAN.
Another aspect of the invention relates to a cell for a radio access network,
comprising: a receiving device in the form of a base station as indicated above,
and a plurality of machine devices of the type described above. The cell may be
part of a RAN which provides M2M communication over the RACH. The pre¬
requisite for performing the communications is that the RAN provides the
possibility to decode signals in a frequency range which allows taking the
Doppler shift into account, which is the case e.g. with the LTE (advanced)
standard, or other standards which provide this possibility.
Further features and advantages are stated in the following description of
exemplary embodiments, with reference to the figures of the drawing, which
shows significant details, and are defined by the claims. The individual features
can be implemented individually by themselves, or several of them can be
implemented in any desired combination.
Brief Description of the Figures
Exemplary embodiments are shown in the diagrammatic drawing and are
explained in the description below. The following are shown:
Fig. 1 shows a schematic diagram of a cell according to the invention,
providing M2M communications over a RACH channel for a
plurality of sensor devices,
Figs. 2a,b show time / frequency diagrams for two different ways of
transmitting a plurality of RACH preambles by one of the sensor
devices of Fig. 1, and
Fig. 3 shows a schematic representation of a machine network according
to the invention.
Description of the Embodiments
The functions of the various elements shown in the Figures, including any
functional blocks labeled as 'processors', may be provided through the use of
dedicated hardware as well as hardware capable of executing software in
association with appropriate software. When provided by a processor, the
functions may be provided by a single dedicated processor, by a single shared
processor, or by a plurality of individual processors, some of which may be
shared. Moreover, explicit use of the term 'processor' or 'controller' should not
be construed to refer exclusively to hardware capable of executing software,
and may implicitly include, without limitation, digital signal processor (DSP)
hardware, network processor, application specific integrated circuit (ASIC), field
programmable gate array (FPGA), read only memory (ROM) for storing
software, random access memory (RAM), and non volatile storage. Other
hardware, conventional and/or custom, may also be included. Similarly, any
switches shown in the Figures are conceptual only. Their function may be
carried out through the operation of program logic, through dedicated logic,
through the interaction of program control and dedicated logic, or even
manually, the particular technique being selectable by the implementer as more
specifically understood from the context.
Fig. 1 shows a radio access network RAN according to the LTE (advanced)
standard which has a plurality of cells, only one of which (cell C) being shown
for the sake of simplicity. The cell C comprises a base station BS and serves a
plurality of machine devices in the form of sensor devices S 1 to Sn not
supporting human activated services, as well as user equipments supporting
such services only one of which (user equipment UE) is represented in Fig. 1.
The sensor devices S 1 to Sn as well as the user equipments UE perform
communications over a Random Access Channel RACH to get the attention of
the base station BS in order to initially synchronize their transmissions with the
base station BS.
In the present example, the Random Access Channel RACH is also used for
providing information from specific ones of the sensor devices S 1 to Sn to the
base station BS. For this purpose, a sensor device, e.g. the first sensor device
S 1, transmits a plurality of RACH preambles P 1 to P3 over the Random Access
Channel RACH, as indicated in Figs. 2a,b, the information being encoded in the
specific way in which the transmission of the RACH preambles P 1 to P3 is
performed, as will be outlined below.
In the example shown in Fig. 2a, three RACH preambles P 1 to P3 are
transmitted subsequently at time instances tO to t3 by the first sensor device S 1,
a (constant) timing offset At / time interval being provided between subsequent
ones of the time instances tO to t3. Moreover, the RACH preambles P1 to P3
are transmitted using frequency offsets +Af, - etc. with respect to each other.
In the present example, the sensor device S 1 is stationary and provides the first
RACH preamble P 1 with a frequency which does not deviate from a nominal
frequency of the RACH channel, represented as 0 Hz in Fig. 2a.
The second preamble P2 is transmitted with a positive frequency offset of =
+1000 Hz with respect to the nominal frequency, whereas the third preamble P3
is transmitted with a negative frequency offset of A = -1000 Hz with respect to
the nominal frequency of the Random Access Channel RACH.
In the present example, an identical spacing for the time and frequency offsets
is chosen for all of the sensor devices S 1 to Sn, defining a two-dimensional grid
in which specific points in frequency and time (frequency hopping pattern) are
defined for each sensor device S 1 to Sn, providing an individual signature
allowing to identify a specific one of the sensor devices S 1 to Sn in a unique
way.
In the example of Fig. 2a, identification of a the first sensor device S 1 is
provided by identifying its (unique) signature of the three subsequent frequency
offsets with values 0, + 1, - 1, transmitted at respective times t , t , and t2. It will
be understood that Fig. 2a shows only a simple example of a time/frequency
grid and that both the number of different frequency offsets and the number of
subsequent transmissions of RACH preambles may be higher or lower than
those indicated in Fig. 2a. In a similar manner, the second sensor device S2
may be identified by a sequence of frequency offsets being e.g. 0, - 1, + 1, etc.
Fig. 2a also shows a power level p of the uplink RACH preambles P 1 to P3.
During the RACH procedure, different (discrete) power ramp up steps may have
to be performed until a power level is reached which allows successful
communication with the RAN. The last power ramp up level, i.e. the power level
which allows a successful RACH procedure, is stored in the sensor device S1.
In a subsequent RACH procedure, either the stored power level may be used
as a first ramp up level, or a power level just below the stored power level may
be used as first power level of the subsequent RACH procedure. In this way,
the power consumption of the RACH procedure may be reduced, as a smaller
number of power ramp up steps will be required.
Instead of using a sequence of RACH preambles P 1 to P3 transmitted at
different points of time, it is also possible to transmit all or at least some of the
RACH preambles P 1 to P3 at the same instant of time tO, as indicated in Fig.
2b. Typically, when this option is used, a relatively high number of different
frequency levels is required for encoding the information. In order to reduce the
number of frequency levels, the information to be provided to the Random
Access Network RAN can additionally be encoded by selecting a specific RACH
preamble content, in the present case a sequence number Co, C , C2. In this
way, the three RACH preambles P 1 to P3 can be differentiated by their content,
as indicated in Fig. 2b (for a simple graphical representation only) by three
different amplitudes of the RACH preambles P 1 to P3, and identification of a
specific sensor device S 1 is possible in the RAN by comparing the signature of
the sequence numbers C0 = 2 , C-i = , and C2 = 3 with pre-defined signatures of
a plurality of sensor devices S 1 to Sn.
As indicated above, it is also possible to combine the coding of Fig. 2b with that
of Fig. 2a, i.e. to combine frequency coding with time and/or with content
coding. In any case, the different frequencies of the RACH preambles P 1 to P3
have to be decoded by the base station BS, which is implemented as an eNB in
the present example of a Radio Access Network RAN in compliance with the
LTE standard. As the base station BS has the capability to decode signals
transmitted on the RACH which deviate from the nominal frequency of the
RACH by an offset due to a Doppler shift which may be e.g. in the order of +/-
1000 Hz or more, the base station BS may be used to decode the information
as a signature within a grid of frequency offsets having an equal spacing and
ranging e.g. from - 3, -2 , - A to +, +2 , +3 +, etc. In addition, the
base station BS is also capable to determine the content of the RACH
preambles P 1 to P3, and to correlate the content of the RACH preambles with
the specific time instant and frequency at which it is received.
As it is mandatory for the base station BS to first identify a particular sensor
device S 1 to Sn before it can make use of status information which is provided
by that sensor device S 1 to Sn, the base station BS compares the specific
frequency, time and/or content of the received RACH preambles with stored
information about pre-configured frequency offsets and possibly pre-configured
timing offsets and content which is used as a signature (coding) allowing to
identify a specific one of the sensor devices.
Although in the above description it has been proposed to use the same
spacing of frequency offsets for all sensor devices S 1 to Sn, it may also be
possible to differentiate the sensor devices S 1 to Sn by selecting a specific
frequency spacing and/or time spacing (i.e. a specific time/frequency grid) for
each sensor device S 1 to Sn which allows to identify that specific sensor device
S 1 to Sn. In this case, the signature / pattern which is provided in the sensorspecific
grid can be used entirely to provide status information to the RAN.
Alternatively, for transmitting sensor-specific status information, the sensor
devices S 1 to Sn may be identified e.g. by pre-defined number of RACH
preambles which are the first ones in a transmitted sequence, the remaining
RACH preambles of the sequence being used for the providing status
information about the specific sensor device S 1 to Sn to the Radio Access
Network RAN. It will be understood that alternatively, the mere transmission of a
RACH sequence may be sufficient to indicate that something is wrong with the
component / machine which is monitored by that specific sensor device. In
particular, the sensor device may only transmit a RACH preamble when a
quantity measured by the sensor device, e.g. a temperature, deviates from a
targeted range.
Furthermore, for an energy efficient sensor implementation, a network preconfiguration
may be uploaded on site during the first setup of the sensor
devices S 1 to Sn, i.e. an operator may store pre-configured network-specific
parameters of the higher layers (above the physical layer) of the radio network,
resp., of the cell C which serves the sensor devices S 1 to Sn, when installing
the sensor devices S 1 to Sn in the field.
The higher-layer network parameters may be stored in the sensor devices S 1 to
Sn during their entire lifetime (especially in the case of static sensor devices),
or, alternatively, the higher layer parameters may be updated regularly or when
a sensor-relevant network parameter change occurs. In this way, a complete
hardware and/or software integration of the higher network layers in the sensor
devices S 1 to Sn can be dispensed with.
In particular, an update or initialization of the sensor devices S 1 to Sn may be
performed in a way which will be explained now with reference to Fig. 3,
showing a machine network MN comprising a master sensor device MS which
is adapted to receive current network configuration parameters LP2, LP3 of the
second and third layer of the LTE standard from the radio access network RAN
(see Fig. 1) , and is further adapted to distribute the network configuration
parameters LP2, LP3 to the plurality of sensor devices S 1 to Sn for updating
pre-configured semi-static network parameters LP2s, LP3s currently stored in
the (slave) sensor devices S 1 to Sn.
The sensor devices S 1 to Sn will then update the sensor parameters LP2s,
LP3s, i.e. they will replace them with the values LP2, LP3 currently received
from the master device MS. The advantage of the configuration of Fig. 3 is that
the sensor devices S to Sn and the master sensor device MS may use a
specific sensor interface for the communication, which may be wire-based (via
cabling) or wireless, typically using a short-range wireless communication
standard, e.g. a ZigBee standard, thus reducing the power consumption for the
communications. It will be understood that the RACH preambles may also be
sent from the sensor devices S 1 to Sn via the master sensor device MS to the
RAN.
Of course, the sensor devices S 1 to Sn of the machine network MN may also
provide the RACH preambles P 1 to P3 directly to the RAN. For this purpose, an
exemplary sensor device Sn shown in Fig. 3 comprises a transmission unit TU
for wireless communications with the RAN over the Random Access Channel
RACH. In addition, the sensor device Sn also comprises an encoding unit EU
for encoding information to be provided to the radio access network RAN over
the Random Access Channel RACH, the encoding unit EU being adapted to
encode the information in the way described with reference to Figs. 2a, b above,
i.e. using specific patterns in the frequency, and possibly in the time and/or
code / content domain.
In the way described above, the communication of the (access) network with a
large number (e.g. several hundreds) of sensors spread in a cell may be
handled in a way which does not overload the network, and makes efficient use
of radio network resources for M2M communications, such that legacy services
(e.g. voice) will not suffer from the additional communications with the sensor
devices.
Those skilled in the art will appreciate that the transfer of encoded information
to the Radio Access Network RAN over the Random Access Channel RACH is
not limited to sensor devices. In particular, user equipments UE (see Fig. 1)
which allow human interactions may also be provided with this additional
communication functionality.
Moreover, it will be appreciated that although the above description has been
given with respect to a radio access network in compliance with the LTE
(advanced) standard, it may be applied equally well to radio networks using a
Random Access Channel and which allow decoding of signals in the Random
Access Channel within a certain frequency range deviating from a nominal
frequency in order to take Doppler shifts into account.
It should be appreciated by those skilled in the art that any block diagrams
herein represent conceptual views of illustrative circuitry embodying the
principles of the invention. Similarly, it will be appreciated that any flow charts,
flow diagrams, state transition diagrams, pseudo code, and the like represent
various processes which may be substantially represented in computer
readable medium and so executed by a computer or processor, whether or not
such computer or processor is explicitly shown.
Also, the description and drawings merely illustrate the principles of the
invention. It will thus be appreciated that those skilled in the art will be able to
devise various arrangements that, although not explicitly described or shown
herein, embody the principles of the invention and are included within its scope
Furthermore, all examples recited herein are principally intended expressly to
be only for pedagogical purposes to aid the reader in understanding the
principles of the invention and the concepts contributed by the inventor(s) to
furthering the art, and are to be construed as being without limitation to such
specifically recited examples and conditions. Moreover, all statements herein
reciting principles, aspects, and embodiments of the invention, as well as
specific examples thereof, are intended to encompass equivalents thereof.
1
New Claims
. Method for providing information from a machine device, in particular
from a sensor device (S1 to Sn), to a radio access network (RAN),
comprising:
transmitting, by the machine device S1 to Sn), a plurality of Random
Access Channel preambles (P1 to P3) over a Random Access Channel
(RACH),
characterized in that
the information is encoded by transmitting the Random Access Channel
preambles (P1 to P3) with pre-selected frequency offsets (0, +M, - )
relative to each other.
2. Method according to claim 1, wherein the information is also encoded by
transmitting the Random Access Channel preambles (P1 to P3) with pre¬
selected timing offsets (At) relative to each other.
3. Method according to claim 1 or 2, wherein two or more of the Random
Access Channel preambles (P1 to P3) are transmitted at the same point
of time (t0) .
4. Method according to any one of the preceding claims, wherein the
information is also encoded using the content of the Random Access
Channel preambles (P1 to P3), in particular their sequence numbers (Co,
C , C2).
5. Method according to any one of the preceding claims, wherein at least
one of the frequency offsets (0, +, -A ), the timing offsets (At), and the
content of the Random Access Channel preambles (PI to P3) is pre2
configured in the machine device (S1 to Sn) upon installation of the
machine device (S1 to Sn).
6. Method according to any one of the preceding claims, wherein the
encoded information comprises identification information for identifying
the machine device (S1 to Sn) and/or status information for informing the
radio access network (RAN) about a status of the machine device (S1 to
Sn).
7. Method according to any one of the preceding claims, wherein the
Random Access Channel preambles (P1 to P3) are transmitted using a
power level (p) which is selected based on a power level of a previous
successful communication between the machine device (S1 to Sn) and
the radio access network (RAN) over the Random Access Channel
(RACH).
8. Machine device, in particular sensor device (Sn), comprising:
a transmission unit (TU) adapted for transmitting a plurality of Random
Access Channel preambles (P1 to P3) over a Random Access Channel
(RACH) to a radio access network (RAN), and
an encoding unit (EU) for encoding information to be provided to the
radio access network (RAN) over the Random Access Channel (RACH),
characterized in that
the encoding unit (EU) is adapted to encode the information by selecting
frequency offsets (0, +, -) between the Random Access Channel
preambles (P1 to P3) to be transmitted by the transmission unit (TU).
9. Machine device according to claim 8, wherein the encoding unit (EU) is
further adapted to select timing offsets (At) between the Random Access
Channel preambles (P1 to P3) for encoding the information.
3
10. Machine device according to claim 8 or 9, wherein the encoding unit (EU)
is further adapted to select the content of the Random Access Channel
preambles (P1 to P3), in particular their sequence numbers (Co, Ci, C2) ,
for encoding the information.
11.Machine device according to any one of claims 8 to 10, being adapted to
use pre-configured network configuration parameters, in particular re
configured higher layer parameters (LP2, LP3), of the radio access
network (RAN) for communication over the Random Access Channel
(RACH).
12. Machine network (MN) comprising a plurality of machine devices (S1 to
Sn) according to any one of claims 8 to 1 , the machine network (MN)
further comprising: a master machine device (MS) adapted to receive
network configuration parameters (LP2, LP3) from the radio access
network (RAN), and to distribute the network configuration parameters
(LP2, LP3) to the plurality of machine devices (S1 to Sn) for updating
pre-configured network parameters, in particular higher layer parameters
(LP2S, LP3s), used in the machine devices (S1 to Sn) for communication
with the radio access network (RAN) over the Random Access Channel
(RACH).
13. Receiving device, in particular base station (BS), for communicating over
a Random Access channel (RACH) with at least one machine device (S1
to Sn) according to any one of claims 8 to 1 ,
characterized in that
the receiving device (BS) is adapted to decode the information encoded
in the pre-selected frequency offsets (0, +M, -) between the Random
4
Access Channel preambles (P1 to P3) transmitted by the at least one
machine device (S1 to Sn).
14. Receiving device according to claim 13, adapted to identify the machine
5 device (S1 to Sn) by comparing the decoded information with stored
information about pre-configured frequency offsets (0, + , -Af) of the
Radio Access Channel preambles (P1 to P3) of a plurality of different
machine devices (S1 to Sn).
i o 15. System (C) for a radio access network (RAN), comprising;
a base station (BS) according to claim 13 or 14, and
a plurality of machine devices (S1 to Sn) according to any one of claims
8 to 11.