U.S. patent application number 14/845521 was filed with the patent office on 2017-03-09 for determining distances.
The applicant listed for this patent is Nokia Technologies Oy. Invention is credited to Olli Alanen, Mika Kasslin, Jarkko Kneckt, Janne Marin.
Application Number | 20170070855 14/845521 |
Document ID | / |
Family ID | 56876902 |
Filed Date | 2017-03-09 |
United States Patent
Application |
20170070855 |
Kind Code |
A1 |
Alanen; Olli ; et
al. |
March 9, 2017 |
Determining Distances
Abstract
An apparatus and a method for determining distances between
apparatuses are disclosed. The method in a first apparatus includes
joining a network including a set of apparatuses; setting a first
predetermined operating mode for the first apparatus after joining
the network; receiving from at least one second apparatus belonging
to the net-work a message indicating a support for a ranging
service from the second apparatus. As a response to the message, a
ranging process with the second apparatus is initiated. A second
predetermined operating mode is set for the first apparatus after
completing the ranging process with the second apparatus network;
and a range-limited service discovery frame is broadcast.
Inventors: |
Alanen; Olli; (Vantaa,
FI) ; Marin; Janne; (Espoo, FI) ; Kneckt;
Jarkko; (Espoo, FI) ; Kasslin; Mika; (Espoo,
FI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nokia Technologies Oy |
Espoo |
|
FI |
|
|
Family ID: |
56876902 |
Appl. No.: |
14/845521 |
Filed: |
September 4, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 76/14 20180201;
H04W 84/12 20130101; H04W 48/16 20130101; H04W 8/005 20130101; H04W
4/023 20130101 |
International
Class: |
H04W 4/02 20060101
H04W004/02; H04W 48/16 20060101 H04W048/16 |
Claims
1. A method comprising: joining, by a first apparatus, a network
comprising a set of apparatuses; setting an operating mode to a
first predetermined operating mode for the first apparatus after
joining the network; receiving, by the first apparatus, from a
second apparatus belonging to the network a message indicating a
support for a ranging service from the second apparatus; in
response to receiving the message, initiating, by the first
apparatus, a ranging process with the second apparatus if and only
if the operating mode is set to the first predetermined operating
mode, wherein initiating the ranging process comprises transmitting
a request to initiate a distance measurement between the first
apparatus and the second apparatus, and wherein the ranging process
comprises determining a distance between the first apparatus and
the second apparatus based on time stamps of frames transferred,
after receiving the message, between the first apparatus and the
second apparatus; setting, by the first apparatus, the operating
mode to a second predetermined operating mode for the first
apparatus after completing the ranging process with the second
apparatus; and broadcasting, the first apparatus, a range-limited
service discovery frame.
2. The method of claim 1, wherein the message comprises indication
of a time and channel the ranging service is offered.
3. The method of claim 1, further comprising: receiving from a
third apparatus belonging to the network a second message
indicating a support for a ranging service from the third
apparatus; and in response to receiving the second message,
initiating a ranging process with the third apparatus.
4. The method of claim 1, wherein the message triggers the ranging
process on the same channel the message was transmitted on.
5. The method of claim 1, further comprising: performing one-to-one
ranging process with apparatuses belonging to the network after
broadcasting the range-limited service discovery frame.
6. An apparatus comprising: at least one processor and at least one
memory including computer program code, the at least one
non-transitory memory and the computer program code configured to,
with the at least one processor, cause the apparatus at least to:
join network comprising a set of apparatuses; set an operating mode
to a first predetermined operating mode for the apparatus after
joining the network; receive from a second apparatus belonging to
the network a message indicating a support for a ranging service
from the second apparatus; in response to receipt of the message,
initiate a ranging process with the second apparatus if and only if
the operating mode is set to the first predetermined operating
mode, wherein initiation of the ranging process comprises
transmitting a request to initiate distance measurement between the
first apparatus and the second apparatus, and wherein the ranging
process comprises determination of a distance between the first
apparatus and the second apparatus based on time stamps of frames
transferred, after receiving the message, between the first
apparatus and the second apparatus; set the operating mode to a
second predetermined operating mode for the apparatus after
completion of the ranging process with the second apparatus; and
broadcast a range-limited service discovery frame.
7. The apparatus of claim 6, the at least one non-transitory memory
and the computer program code, with the at least one processor,
further configured to; detect, from the message, indication of a
time and channel the ranging service is offered.
8. The apparatus of claim 6, the at least one non-transitory memory
and the computer program code, with the at least one processor,
further configured to: receive from a third apparatus belonging to
the network a message indicating a support for a ranging service
from the third apparatus; in response to receiving the message,
initiate a ranging process with the third apparatus.
9. The apparatus of claim 6, the at least one non-transitory memory
and the computer program code, with the at least one processor,
further configured to: initiate on the basis of the message the
ranging process on the same channel the message was transmitted
on.
10. The apparatus of claim 6, the at least one non-transitory
memory and the computer program code, with the at least one
processor, further configured to: perform one-to-one ranging
process with apparatuses belonging to the network after
broadcasting the range-limited service discovery frame.
11. A computer program product embodied on a non-transitory
distribution medium readable by a computer and comprising program
instructions which, when loaded into an apparatus, cause the
apparatus to: join a network comprising a set of apparatuses; set
an operating mode to a first predetermined operating mode for the
first apparatus after joining the network; receive from a second
apparatus belonging to the network a message indicating a support
for a ranging service from the second apparatus; in response to
receipt of the message, initiate a ranging process with the second
apparatus if and only if the operating mode is set to the first
predetermined operating mode, wherein initiation of the ranging
process comprises transmitting a request to initiate distance
measurement between the first apparatus and the second apparatus,
and wherein the ranging process comprises determination of a
distance between the first apparatus and the second apparatus based
on time stamps of frames transferred, after receiving the message,
between the first apparatus and the second apparatus; set the
operating mode to a second predetermined operating mode for the
first apparatus after completion of the ranging process with the
second apparatus; and broadcast a range-limited service discovery
frame.
12. The computer program product of claim 11, wherein the message
comprises indication of a time and channel the ranging service is
offered.
13. The computer program product of claim 11, wherein the apparatus
is further caused to: receive from a third apparatus belonging to
the network a second message indicating a support for a ranging
service from the third apparatus; and in response to the second
message, initiate a ranging process with the third apparatus.
14. The computer program product of claim 11, wherein the message
triggers the ranging process on the same channel the message was
transmitted on.
15. The computer program product of claim 11, wherein the apparatus
is further caused to: perform one-to-one ranging process with
apparatuses belonging to the network after broadcasting the
range-limited service discovery frame.
Description
TECHNICAL FIELD
[0001] The invention relates to communications.
BACKGROUND
[0002] In wireless communication systems there may be situations
for a transceiver when it might be useful to be able to know the
location of another transceiver or distance to the transceiver.
BRIEF DESCRIPTION
[0003] According to an aspect, there is provided the subject matter
of the independent claims. Embodiments are defined in the dependent
claims.
[0004] One or more examples of implementations are set forth in
more detail in the accompanying drawings and the description below.
Other features will be apparent from the description and drawings,
and from the claims.
BRIEF DESCRIPTION OF DRAWINGS
[0005] Embodiments of the present invention are described below, by
way of example only, with reference to the accompanying drawings,
in which
[0006] FIGS. 1A and 1B illustrate examples of wireless
communication scenarios to which embodiments of the invention may
be applied;
[0007] FIG. 2 illustrates an example of an advertisement protocol
data unit;
[0008] FIG. 3 illustrates an example of transmission of a Discovery
Window DW and further availability FAV;
[0009] FIG. 4 illustrates an example of a cluster of
apparatuses;
[0010] FIG. 5 is a flow chart illustrating an example of an
embodiment;
[0011] FIG. 6 is a signaling charts illustrating an example of an
embodiments; and
[0012] FIG. 7 illustrates a block diagram of an apparatus according
to some embodiments.
DETAILED DESCRIPTION OF SOME EMBODIMENTS
[0013] The following embodiments are examples. Although the
specification may refer to "an", "one", or "some" embodiment(s) in
several locations, this does not necessarily mean that each such
reference is referring to the same embodiment(s), or that the
feature only applies to a single embodiment. Single features of
different embodiments may also be combined to provide other
embodiments. Furthermore, words "comprising" and "including" should
be understood as not limiting the described embodiments to consist
of only those features that have been mentioned and such
embodiments may contain also features/structures that have not been
specifically mentioned.
[0014] A general wireless communication scenario to which
embodiments of the invention may be applied is illustrated in FIG.
1A. FIG. 1A illustrates an example of wireless communication
devices comprising a plurality of access points (AP) 100, 102 and a
plurality of wireless terminal devices (STA) 110, 112, 114, 116,
118. Each base station may be associated with a basic service set
(BSS) which is a basic building block of an IEEE 802.11 wireless
local area network (WLAN). The most common BSS type is an
infrastructure BSS that includes a single AP together with all STAs
associated with the AP. The AP may be a fixed AP or it may be a
mobile AP. The APs 100, 102 may also provide access to other
networks, e.g. the Internet. In another embodiment, the BSS may
comprise a plurality of APs to form an extended service set (ESS).
While embodiments of the invention are described in the context of
the above-described topologies of IEEE 802.11 based networks, it
should be appreciated that these or other embodiments of the
invention may be applicable to networks based on other
specifications, e.g. different versions of the IEEE 802.11, WiMAX
(Worldwide Interoperability for Microwave Access), UMTS LTE
(Long-term Evolution for Universal Mobile Telecommunication
System), and other networks having cognitive radio features, e.g.
transmission medium sensing features and adaptiveness to coexist
with radio access networks based on different specifications and/or
standards.
[0015] Let us consider an infrastructure BSS that includes an
access point together with terminal devices. The access point may
be configured to utilize one or more radio channels or frequencies
in communication with the terminal devices. The access point 100,
102 is configured to inform terminal devices its presence by
transmitting a beacon signal or a beacon frame at predetermined
intervals on each channel it uses for communication. The beacon
frame comprises information on the access point, its network, and
other networks. Typically the predetermined interval is 100 time
units (TU). The duration of one TU is 1,024 ms. A terminal device
may tune to a channel and look for beacon frames. The process is
denoted passive scanning. Upon finding a beacon frame the terminal
device may attempt a connection with the access point by
transmitting an authentication message. After receiving an
authentication response message from the access point, the terminal
device and the access point may exchange association messages after
which the terminal device is said to be associated to the access
point. The association messages may comprise at least one of the
following messages: association request, association response,
reassociation request, and reassociation response. The association
may be followed by 802.1X authentication, IP address allocation and
other application specific setup signaling.
[0016] Another wireless communication scenario to which embodiments
of the invention may be applied is illustrated in FIG. 1B. FIG. 1B
illustrates a plurality of wireless devices 120, 122, 124, 126 that
form a cluster 128 of devices. The cluster may comply with
neighbour awareness networking (NAN) principles. NAN is also
denoted as the Wi-Fi Aware. NAN provides a mechanism for wireless
devices to synchronize the time and channel on which they converge
to facilitate the discovery of services that the devices may offer
to other devices. The time period and channel on which NAN Devices
converge is called the Discovery Window (DW). The wireless devices
of a NAN cluster share a common set of NAN parameters that may
comprise the time period between consecutive Discovery Windows, the
time duration of the Discovery Windows, a beacon interval, and NAN
Channel(s). The devices in a cluster may transmit multicast NAN
Service Discovery frames directly to other devices within range in
the same cluster during the Discovery Window. Devices may also
communicate one to one with each other. A wireless device may
belong to more than one cluster. In addition, a device may operate
concurrently in a cluster and in a different WiFi network such as
an infrastructure BSS of FIG. 1A.
[0017] Some proposals have been made to enhance NAN. Especially a
more accurate ranging has been proposed between the NAN devices. A
NAN device may utilize the ranging result in filtering the service
discovery frames. It has been proposed that a NAN device should be
able to e.g. search for a Service IDs with a predetermined range
(such as 30 meters, for example) and in this case, only the devices
with the required Service ID and within the required range, should
reply to the query.
[0018] One possible technology to realise ranging is based on IEEE
802.11 Fine Timing Measurement (FTM). In one exemplary realisation
of FTM, typically three frame pairs are required to complete the
ranging process. First the initiating apparatus transmits a request
to initiate distance measurement. The responding apparatus
acknowledges the request. Then follow the actual ranging messages
between the apparatuses. Both stations time stamp the transmission
and reception times of these messages. The time stamps may be
denoted as t1, t2, t3, and t4. The responding apparatus is
configured to transmit at time instant t1 an FTM_1 message. The
initiating apparatus receives the message at time instant t2 and
transmits acknowledgement message at time instant t3. The
responding apparatus receives the ACK transmitted by the initiating
apparatus at time instant t4.
[0019] Finally, the responding apparatus transmits an FTM_2 message
to inform the initiating apparatus on the transmission time t1 of
the FTM_1 message and the reception time t4 of the corresponding
ACK. After this message exchange, the initiating apparatus can
determine distance to the responding apparatus.
[0020] The numbers of NAN devices in a cluster (local network) may
in some cases be quite large. One of the challenges is to make the
ranging scalable in case where there are many nodes in the cluster.
Currently the approach has been that each NAN device entering a
cluster is to perform one-to-one discovery with each existing node
of the cluster. A complete service discovery amongst all NAN
devices may take a long time and would not therefore be
practical.
[0021] In an embodiment, it is proposed that a cluster of NAN
devices offers ranging service for NAN devices having just joined
into the cluster. When a new NAN device joins a NAN cluster, it may
be configured to first search for devices of the cluster offering
the ranging service. In an embodiment, the location of the
device(s) of the cluster offering the service is static or semi
static. The NAN device of the cluster offering the ranging service
may indicate the service in its Beacons or Service Discovery
Frames. For example, a Service Name may be specific and advertised
for indication. Alternatively, it may be indicated with a new
attribute (such as WLAN infrastructure attribute) or capability and
advertised. For example, if a Service Name is used as the
indication, the actual advertisement protocol data unit PDU may
look like one in FIG. 2. In the example, the Service ID may
identify the ranging service and the Further Availability Map
attribute may describe when the device is available for the ranging
service.
[0022] Once one or more such devices advertising the service are
found, the new NAN device may be configured to perform ranging with
some of them. Other devices of the cluster may be configured to
listen or observe for the ranging and calculate their distance to
the new device based on the results.
[0023] At the next step, all the NAN devices of the cluster know
their range to the new node and may thereafter reply to the
range-limited service discovery frames accordingly.
[0024] According to NAN specification each device of, a NAN cluster
has a specified master preference value. The specification suggests
that moving device should select a low Master Preference value and
low mobility devices should select a high Master Preference value.
Especially, devices with static location may be considered as
infrastructure devices which are suggested to select a value of 128
or greater as their master preference value, and other devices
should select a value below 128. In an embodiment, the NAN devices
of the cluster having a master preference value over 128 may be
configured to offer the ranging service.
[0025] Typically, each NAN cluster there is one NAN device which is
the Anchor Master of the cluster. In an embodiment, the Anchor
Master of the cluster is configured to offer the ranging service to
the NAN devices joining the cluster.
[0026] The NAN device joining the cluster may deduce from the
ranging service indication the time when the device transmitting
the indication is available for ranging (hereafter denoted as
further availability or FAV). FIG. 3 illustrates an example, where
the device transmitters the indication using a Discovery Window
(DW) 300 on the NAN channel 302, where the ranging FAV is
advertised. Later, the actual ranging process may be performed in
another channel 304, in the ranging FAV 306. All the devices of the
cluster may hear the frames in the DW and therefore also know to
listen during the ranging FAV. In an embodiment, the actual ranging
process may be performed on the same channel (NAN channel).
[0027] Next an embodiment is illustrated with the aid of FIGS. 4, 5
and 6. In following, NAN devices offering ranging service are
denoted as static nodes, NAN devices only listening (or observing)
are denoted as observing nodes and the NAN device joining cluster
is denoted as new node.
[0028] In an embodiment, the observing nodes [O1, O2, O3, . . . ,
On] monitor the ranging process between the new node and static
nodes [S1, S2, S3, . . . , Sn] to get the distance to the new node
for both static and observing nodes. FIG. 4 presents a simplified
example scenario, where the ranging process is performed. The
example scenario of FIG. 4 contains one static node S1 400, only
one observer O1 402, and a new node NN 404, for the sake of
simplicity. FIG. 5 is a flow chart illustrating the example.
[0029] In step 500, the new node 404 joins the cluster according to
known NAN procedures.
[0030] In the example case, the roundtrip-time RTT1 is already
known by the observer O1 as it has earlier performed ranging
against S1. S1 is a node that is known or assumed to have somewhat
static position and may be e.g. mains powered. In this example, S1
may be the Anchor Master of the cluster. Node S1 is configured to
publish a service ID with further availability FAV. It is thus
configured to transmit on Discovery Window advertising ranging FAV.
The FAV may define a time and frequency when the S1 is ready to
respond to ranging messages.
[0031] In step 502, the node 404 sets a first predetermined
operating mode for the first apparatus after joining the network.
In an embodiment, the first predetermined operating mode is a so
called new node mode, where the node 404 is configured to respond
to messages on Discovery Window of the cluster advertising ranging
FAV. It is thus able to do ranging with S1 in the ranging FAV.
[0032] In step 504, the node 404 is configured to receive from the
node S1 a message indicating a support for a ranging service. The
message indicating support for the ranging service may be a beacon,
a discovery frame and/or a special message for this purpose.
[0033] In step 506, the node 404 is configured to, as a response to
the message, initiate a ranging process with the node S1.
[0034] In an embodiment, the discovery Window DW may trigger the
ranging process on the same frequency channel used in the
transmission of the DW. In this case there is no need to indicate a
different frequency when advertising ranging FAV.
[0035] FIG. 6 is a signalling chart illustrating an example of the
ranging process.
[0036] The new node NN 404 is configured to transmit a measurement
frame 600 at time instant T1 to the node S1 400. The measurement
frame is received by the node at time instant T2, the elapsed time
being RTT2. The measurement frame is also received by the observing
node O1 402 at time instant Tc1. In the figure Tel is later than
T2, but in reality the order may naturally be different. The
difference Tc1-T1 is denoted as RTT3.
[0037] The node S1 is configured to transmit acknowledgement frame
602 at time instant T3. The acknowledgement frame is received by
the new node NN at time instant T4 and by the observing node O1 at
time instant Tc2.
[0038] The new node NN is configured to transmit measurement report
604 comprising T1, T4 and RTT2. The measurement report is received
by the node S1 and observing node O1.
[0039] As a result of the ranging process, the new node NN will get
the RTT2 estimate between the new node and the node S1. On the
basis of RTT2 the distance may be calculated by multiplying it with
the speed of light.
[0040] Returning to the flow chart of FIG. 5, in step 508, the node
404 is configured to set a second predetermined operating mode for
the node after completing the ranging process with the node S1. In
an embodiment, the second predetermined operating mode is a so
called old node mode, where there is no need to respond to the
ranging FAV advertisements.
[0041] In step 510, the node 404 is configured to broadcast a
range-limited service discovery frame.
[0042] The process ends.
[0043] The observer node O1 listens and receives all communication
between the new node NN and the node S1 during the ranging process.
It is also configured to record the time stamps related to the
measurement and acknowledgement frames. When the ranging process
has finished, the observing node may be configured to determine RTT
between the new node NN and the observing node O1 for example
utilising the equation:
RTT3=T4-T1-Tc2+Tc1-RTT2+RTT1.
[0044] The distance between the new node NN and the observing node
O1 may be calculated on the basis of RTT3 by multiplying it with
the speed of light.
[0045] As the observing node O1 is now aware of the distance
between the new node NN and the observing node is capable of
determining whether to utilise a range-limited services advertised
by the new node.
[0046] On the basis of the above ranging service the new node NN
may quickly get responses to range-limited service discovery frames
when accessing a NAN cluster, without needing to perform first
one-to-one ranging with each member of the NAN cluster. This
enables the new node to get access some a range-limited service
quickly. The new node may perform normal one-to-one ranging with
the nodes of the cluster at some phase later, when there is
suitable time. This way the service discovery with range limit may
be started immediately.
[0047] All the nodes of the cluster may be configured to listen the
message exchange during the ranging process. If successfully
receiving the messages, they may get their range estimate to the
new node. In an embodiment, the new node NN may also perform
ranging to more than one node transmitting indication of ranging
service to make the measurement more reliable by averaging the
ranging results.
[0048] FIG. 7 illustrates an embodiment of an apparatus comprising
means for carrying out the above-mentioned functionalities. In an
embodiment, the apparatus may be a wireless device which complies
with specifications of an IEEE 802.11 based network or another
wireless network. The wireless apparatus may also be, a cognitive
radio apparatus capable of adapting its operation to a changing
radio environment, e.g. to changes in parameters of another system
on the same frequency band. The wireless apparatus may be or may be
comprised in a computer (PC), a laptop, a tablet computer, a
cellular phone, a palm computer, a base station with routing
functionalities, or any other apparatus provided with radio
communication capability. In an embodiment, the apparatus carrying
out the above-described functionalities is comprised in such a
wireless device, e.g. the apparatus may comprise a circuitry, e.g.
a chip, a processor, a micro controller, or a combination of such
circuitries in the wireless device.
[0049] Referring to FIG. 7, the apparatus may comprise a
communication controller circuitry 700 configured to control
wireless communications in the wireless device. The communication
controller circuitry 700 may comprise a control part 702 handling
control signalling communication with respect to transmission,
reception, and extraction of control or management frames including
the beacon frames, initial link setup frames, measurement frames
and acknowledgement frames, for example. The communication
controller circuitry 700 may further comprise a data part 704 that
handles transmission and reception of payload data during
transmission opportunities of the wireless device (transmission) or
transmission opportunities of other wireless devices
(reception).
[0050] The communication controller circuitry 700 may further
comprise a locationing part 706 configured to control operations
related to locationing messages and determining distances to nearby
apparatuses on the basis of messages. In an embodiment, the control
part 702 forwards information related to locationing messages to
the locationing part 706.
[0051] In an embodiment, the communication channel utilized by the
apparatus is a wireless local area network channel. In an
embodiment, the communication channel is defined by a center
frequency and a channel width. In an embodiment, the communication
channel has a 20 Mhz channel width. In an embodiment, the
communication channel is a primary channel according to IEEE 802.11
specs, e.g. IEEE 802.11-2012.
[0052] The apparatus may further comprise a user interface 708
enabling interaction with the user of the communication device. The
user interface may comprise a display, a keypad or a keyboard, a
loudspeaker, etc.
[0053] If the apparatus is an infrastructure device or an access
point, the apparatus may further comprise a communication part 710
configured to communicate 712 with other network elements such as
other access points, network controllers and networks.
[0054] The circuitries 702 to 706 of the communication controller
circuitry 700 may be carried out by the one or more physical
circuitries or processors. In practice, the different circuitries
may be realized by different computer program modules. Depending on
the specifications and the design of the apparatus, the apparatus
may comprise some of the circuitries 702 to 706 or all of them.
[0055] The apparatus may further comprise the memory 714 that
stores computer programs (software) configuring the apparatus to
perform the above-described functionalities of the access point.
The memory 714 may also store communication parameters and other
information needed for the wireless communications within a
wireless network of the access point and with other wireless
networks.
[0056] The apparatus may further comprise radio interface
components 716 providing the apparatus with radio communication
capabilities within its wireless network and/or with other wireless
networks. The radio interface components 716 may comprise standard
well-known components such as an amplifier, filter,
frequency-converter, (de)modulator, and encoder/decoder circuitries
and one or more antennas.
[0057] As used in this application, the term `circuitry` refers to
all of the following: (a) hardware-only circuit implementations,
such as implementations in only analogue and/or digital circuitry,
and (b) to combinations of circuits and software (and/or firmware),
such as (as applicable): (i) a combination of processor(s) or (ii)
portions of processor(s)/software including digital signal
processor(s), software, and memory(ies) that work together to cause
an apparatus to perform various functions, and (c) to circuits,
such as a microprocessor(s) or a portion of a microprocessor(s),
that require software or firmware for operation, even if the
software or firmware is not physically present. This definition of
`circuitry` applies to all uses of this term in this application.
As a further example, as used in this application, the term
"circuitry" would also cover an implementation of merely a
processor (or multiple processors) or portion of a processor and
its (or their) accompanying software and/or firmware. The term
"circuitry" would also cover, for example and if applicable to the
particular element, a baseband integrated circuit or applications
processor integrated circuit for a wireless device.
[0058] The processes or methods described in FIGS. 2 to 6 may also
be carried out in the form of a computer process defined by a
computer program. The computer program may be in source code form,
object code form, or in some intermediate form, and it may be
stored in a transitory or a non-transitory carrier, which may be
any entity or device capable of carrying the program. Such carriers
include a record medium, computer memory, read-only memory,
electrical carrier signal, telecommunications signal, and software
distribution package, for example. Depending on the processing
power needed, the computer program may be executed in a single
electronic digital processing unit or it may be distributed amongst
a number of processing units.
[0059] The present invention is applicable to wireless networks
defined above but also to other suitable wireless communication
systems. The protocols used, the specifications of wireless
networks, their network elements and terminals, develop rapidly.
Such development may require extra changes to the described
embodiments. Therefore, all words and expressions should be
interpreted broadly and they are intended to illustrate, not to
restrict, the embodiment. It will be obvious to a person skilled in
the art that, as technology advances, the inventive concept can be
implemented in various ways. The invention and its embodiments are
not limited to the examples described above but may vary within the
scope of the claims.
* * * * *