U.S. patent application number 10/909159 was filed with the patent office on 2005-01-13 for communication system.
This patent application is currently assigned to Telefonaktiebolaget LM Ericsson (publ). Invention is credited to Alexius, Staffan, Dovner, Lars, Granberg, Olof Axel, Smolentzov, Andre.
Application Number | 20050009506 10/909159 |
Document ID | / |
Family ID | 20415518 |
Filed Date | 2005-01-13 |
United States Patent
Application |
20050009506 |
Kind Code |
A1 |
Smolentzov, Andre ; et
al. |
January 13, 2005 |
Communication system
Abstract
The present invention relates to methods and means for creating
a cellular radio communication system (100) out of a number of
local radio networks (109, 110), e.g. piconets. The local radio
networks (109,110) are unsynchronised with each other and uses a
radio interface that has no broadcast channel, e.g. the Bluetooth
radio interface. A control unit (108) is connected to each local
radio network to provide the basic means and methods for a cellular
radio communication system (100). Radio units (101-103) can attach
and retain a connection to the control unit (108) via their
respective radio node (104-107). The radio units (101-103) can also
perform roaming, handover, measurments and fast connection set-ups
in the system (100).
Inventors: |
Smolentzov, Andre; (Solna,
SE) ; Granberg, Olof Axel; (Sollentuna, SE) ;
Alexius, Staffan; (Hjarup, SE) ; Dovner, Lars;
(Sundsvall, SE) |
Correspondence
Address: |
ERICSSON INC.
6300 LEGACY DRIVE
M/S EVR C11
PLANO
TX
75024
US
|
Assignee: |
Telefonaktiebolaget LM Ericsson
(publ)
|
Family ID: |
20415518 |
Appl. No.: |
10/909159 |
Filed: |
July 30, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10909159 |
Jul 30, 2004 |
|
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09565551 |
May 5, 2000 |
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6788656 |
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Current U.S.
Class: |
455/411 ;
375/E1.033; 455/426.2 |
Current CPC
Class: |
H04B 1/713 20130101;
H04W 84/02 20130101 |
Class at
Publication: |
455/411 ;
455/426.2 |
International
Class: |
H04M 001/66 |
Foreign Application Data
Date |
Code |
Application Number |
May 7, 1999 |
SE |
9901673-5 |
Jan 29, 2001 |
SE |
514264 |
Claims
1-13. (Canceled)
14. A method for calculating the realtime clock of a first radio
node in a second radio node in a cellular radio communication
system comprising a number of local radio networks utilizing radio
interfaces which, between said local radio networks are
unsynchronized with each other, where each of said local radio
networks comprises a radio node arranged to communicate with a
plurality of radio units comprising: establishing a link between a
first radio unit and both of said first and second radio nodes:
generating a first BRFP realtime clock difference between the
realtime clocks of said first radio node and said second radio node
in a control node associated with said radio nodes; transmitting
said first BRFP realtime clock difference to said second radio
node; and calculating the real time clock of said first radio node
in said second radio node by adding said first BRFP realtime clock
difference to the realtime clock of said second radio node.
15. The method as claimed in claim 14, wherein said step of
generating a first BRFP realtime clock difference comprises the
steps of: calculating a first realtime clock difference between
said first radio unit and said first radio node in said first radio
node; transmitting said first realtime clock difference to said
control node; calculating a second realtime clock difference
between said first radio unit and said second radio node in said
second radio node; transmitting said second realtime clock
difference to said control node; calculating said first BRFP
realtime clock difference in said control unit from said first and
second realtime clock difference.
16. The method as claimed in claim 14, wherein said step of
calculating the realtime clock of said first radio node in said
second radio node is followed by the step of: paging a second radio
unit from said second radio node, where said second radio unit has
established a link to said first radio node.
17. A method for co-ordinating the use of time slots in different
local radio networks in a cellular radio communication system
comprising a number of local radio networks utilizing radio
interfaces which, between said local radio networks, are
unsynchronized with each other and having at least three timeslots,
and where each of said local radio networks comprises a radio node
arranged to communicate with a plurality of radio units the method
comprising: generating a BRFP realtime clock difference between all
the realtime clocks of said radio nodes in said system in a control
node associated with said radio nodes; selecting the realtime clock
of a first one of said radio nodes as a reference clock for all
radio nodes in said system; ordering all radio nodes in said system
to use timeslots co-ordinated with said reference clock of said
first radio node for signalling and payload by using said BRFP
realtime clock differences.
18. The method as claimed in claim 17, wherein said step of
generating a BRFP realtime clock difference between all the
realtime clocks of said radio nodes comprises the steps of:
calculating realtime clock differences in all radio nodes between
their own realtime clocks and said radio units which they are
connected too; transmitting said realtime clock differences to said
control node; calculating said BRFP realtime clock difference from
said calculated realtime clock difference in said control node.
19-24. (Canceled)
25. A control node in a cellular radio communication system
comprising a number of local radio networks utilizing radio
interfaces which, between said local radio networks are
unsynchronized with each other, and where each of said local radio
networks comprises a radio node arranged to communicate with a
plurality of radio units, characterised in that said control node
is connected to at least one radio node in each local radio network
in said system so as to create a cellular radio communication
system out of said local radio networks, and where said control
node is arranged to control the communication in each of said local
radio networks.
26. The control node as claimed in claim 25, wherein said control
node comprises means for establishing a connection from each one of
said radio nodes to said control-node.
27. The control node as claimed in claim 25, wherein said control
node comprises means for identifying, authenticating and
registrating each one of said radio units so that said control node
can direct calls to and from said radio units.
28. The control node as claimed in claim 25, wherein said control
node comprises means for roaming links to radio units between said
radio nodes in said system.
29. The control node as claimed in claim 25, wherein said control
node comprises means for performing handovers of connections to
said radio units between said radio nodes in said system.
30. The control node as claimed in claim 25, wherein said control
node comprises means for generating a BRFP realtime clock
difference between all the realtime clocks of said radio nodes in
said system.
31. The control node as claimed in claim 25, wherein said control
node comprises: means for selecting the realtime clock of a first
one of said radio nodes as a reference clock for all radio nodes in
the system; and means for ordering all radio nodes in said system
to use timeslots coordinated with said reference clock of said
first radio node for signalling and payload.
32. The control node as claimed in claim 25, wherein said control
node comprises: means for creating a neighbouring list by
registrating said radio nodes from which said first radio unit can
detect a signal as neighbours to said first radio node.
33. A control node, comprising: a processor, a memory in
communication with the processor, wherein the memory includes
instructions for calculating the realtime clock of a first radio
node in a second radio node in a cellular radio communication
system comprising a number of local radio networks utilizing radio
interfaces which, between said local radio networks, are
unsynchronized with each other, where each of said local radio
networks comprises a radio node arranged to communicate with a
plurality of radio units, wherein the calculating instructions
comprise instructions for: establishing a link between a first
radio unit and both of said first and second radio nodes:
generating a first BRFP realtime clock difference between the
realtime clocks of said first radio node and said second radio node
in a control node associated with said radio nodes; transmitting
said first BRFP realtime clock difference to said second radio
node; and calculating the real time clock of said first radio node
in said second radio node by adding said first BRFP realtime clock
difference to the realtime clock of said second radio node.
34. The node of claim 33, wherein the instructions for generating a
first BRFP realtime clock difference further comprises instructions
for: calculating a first realtime clock difference between said
first radio unit and said first radio node in said first radio
node; transmitting said first realtime clock difference to said
control node; calculating a second realtime clock difference
between said first radio unit and said second radio node in said
second radio node; transmitting said second realtime clock
difference to said control node; and calculating said first BRFP
realtime clock difference in said control unit from said first and
second realtime clock difference.
35. The node of claim 33, wherein the instructions for calculating
the realtime clock of said first radio node in said second radio
node also contains instructions for paging a second radio unit from
said second radio node, where said second radio unit has
established a link to said first radio node.
36. A control node comprising: a processor, a memory in
communication with the processor, wherein the memory includes
instructions coordinating the use of time slots in different local
radio networks in a cellular radio communication system comprising
a number of local radio networks utilizing radio interfaces which,
between said local radio networks, are unsynchronized with each
other and having at least three timeslots, and where each of said
local radio networks comprises a radio node arranged to communicate
with a plurality of radio units, wherein the instructions for
coordinating comprise instructions for: generating a BRFP realtime
clock difference between all the realtime clocks of said radio
nodes in said system in a control node associated with said radio
nodes; selecting the realtime clock of a first one of said radio
nodes as a reference clock for all radio nodes in said system; and
ordering all radio nodes in said system to use timeslots
coordinated with said reference clock of said first radio node for
signaling and payload by using said BRFP realtime clock
differences.
37. The node of claim 36, wherein the instructions for generating a
BRFP realtime clock difference between all the realtime clocks of
said radio nodes comprises instructions for: calculating realtime
clock differences in all radio nodes between their own realtime
clocks and said radio units which they are connected too;
transmitting said realtime clock differences to said control node;
and calculating said BRFP realtime clock difference from said
calculated realtime clock difference in said control node.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] The present invention relates in general to the field of
radio communication and, in particular, to methods and means for
providing a cellular radio communication system comprising a number
of local radio networks utilising radio interfaces that are
unsynchronised with each other and have no broadcast control
channel.
DESCRIPTION OF RELATED ART
[0002] There are a number of equipments that have some sort of
radio communication means. By "radio unit" is meant all portable
and non-portable equipment intended for radio communication with a
radio communication system. Examples of such radio units are mobile
phones, cordless phones, pagers, telex, electronic notebooks, PCs
and laptops with integrated radios, communicators, computers,
wireless head sets, wireless printers, wireless keyboards or any
other electronic equipment using a radio link as a mean of
communication. These equipments can be used with any type of radio
communication system, such as cellular networks, satellite or small
local radio networks. They can also communicate directly with each
other without using any system.
[0003] Cellular radio communication systems are commonly employed
to provide voice and data communications to a plurality of radio
units or subscribers.
[0004] Examples of such cellular radio communication systems are
e.g. AMPS, D-AMPS, GSM, and IS-95 (CDMA). These systems generally
include a number of base stations serving portable radio units, one
or more base station controllers (BSC) and at least one mobile
switching centre (MSC) or similar. All radio transmissions in the
system are made via a specific radio interface that enables radio
communication between the portable radio units and the base
stations.
[0005] The cellular radio communication system covers a certain
geographical area. This area is typically divided into cells or
regions. A cell typically includes a base station and the radio
units with which the base station is in communication. The cell
associated with the particular base station with which a radio unit
is communicating is commonly called the serving cell.
[0006] To each cell one or more voice/data and/or traffic/control
channels are allocated. Note that "channel" may refer to a specific
carrier frequency in an analogue system, e.g. AMPS, a specific
carrier/slot combination in a hybrid TDMA/FDMA system, e.g. GSM or
one or more assigned codes in a DS-CDMA system.
[0007] The cellular radio communication system usually provides a
broadcast channel on which all radio units can listen to system
information from base stations or measure signal strength and/or
signal quality at regular intervals. Such a channel is called
Broadcast Control Channel in GSM and Page or Access Channel in
D-AMPS.
[0008] The process of changing cells during a call is often called
a handover or handoff. As soon as one of the neighbouring cells is
considered to have a better signal strength/quality than the
serving cell, e.g. by signal measurements on the broadcast channel,
a handover is made to that particular neighbouring cell.
[0009] The ability to move around, changing cells and connections
over the radio interface when the radio unit is switched on or is
in some kind of stand by mode but not engaged in a call is called
roaming. When the radio unit is roaming it listens to the broadcast
channel for information about the system e.g. in which specific
area of the system the radio is presently located.
[0010] Today, a number of low-power, low-cost radio interfaces
between radio units and their accessories are being developed. The
intention is to replace the cables or infrared links, e.g. between
a computer and a printer, with a short-range radio link (a wireless
link) forming a local radio network.
[0011] A suitable frequency band for such a radio-interface is the
2,4 GHz ISM band (the Industrial-Scientific-Medical band) which
ranges from 2,400-2,483 GHz in the US and Europe and from
2,471-2497 GHz in Japan. This frequency band is globally available,
licence-free and open to any radio system.
[0012] There are some rules each radio system has to follow if they
are to use this ISM band, e.g. in the ETSI standard ETS 300328.
Synchronisation between different transmitters in a radio system
using the ISM band is not allowed. Synchronisation is of course
allowed between a transmitter and a receiver, e.g. when two radio
units are communicating with each other. Another rule specifies
that frequency spreading must be used for a radio interface using
the ISM band. The IEEE 802.11 is an example of a specification
utilising the ISM band.
[0013] An example of such a radio interface is called Bluetooth
(see the Telecommunications Technology Journal "Ericsson Review",
No. 3 1998, with the article "BLUETOOTH-The universal radio
interface for ad hoc, wireless connectivity" by Jaap Haartsen).
Bluetooth is an universal radio interface operating within the ISM
band and enables portable electronic devices to connect and
communicate wirelessly via short-range, ad hoc networks (local
radio networks). Bluetooth uses a frequency-hop spread spectrum
technique (FH-CDMA) where the frequency band is divided into
several hop channels. During a connection, radio units with
Bluetooth transceivers hop from one channel to the other in a
pseudo-random fashion. Each channel is divided into a number of
slots in a time division multiplexing scheme, where a different hop
frequency is used for each slot.
[0014] A radio unit with Bluetooth can simultaneously communicate
with up to seven other radio units in a small local radio network
called a piconet. Each piconet is established by a unique
frequency-hopping channel, i.e. all radio units in a specific
piconet share the same frequency hopping scheme. One radio unit
acts as a master, controlling the traffic in the piconet, and the
other radio units in the piconet act as slaves. Any radio unit can
become a master, but only one master may exist in a piconet at any
time (often the one that initiates the connection). It is often the
radio unit that initiates the connection that acts as a master. Any
radio unit may change its role from slave to master or vice versa
(a slave to master or a master to slave switch) Every radio unit in
the piconet uses the master identity and realtime clock to track
the hopping channel. Hence the slaves must be informed of the
identity and the clock of the master before they can communicate
with the master.
[0015] Bluetooth supports both point-to-point (master to a slave)
and point-to-multipoint (master to a number of slaves) connections.
Two slaves can only communicate with each other through a master or
by changing one of the slaves to a master with a slave to master
switch.
[0016] There is no hop or time synchronisation between radio units
in different piconets but all radio units participating in the same
piconet are hop synchronised to one frequency-hopping channel and
time synchronised so that they can transmit or receive at the right
time. This does not contravene the rules of non synchronisation
between transmitters in the ISM band because there is only one
radio unit that is transmitting at any time instant in the
piconet.
[0017] A radio unit can act as a slave in several piconets. This is
achieved by using the time division multiplexing scheme of the
channels where e.g. a first piconet is visited in a first time slot
and a second piconet is visited in a third time slot. There are
three different time slots on each channel where each time slot is
split in two portions, one portion for transmitting and one portion
for receiving.
[0018] There is no broadcast channel (e.g. a Broadcast Control
Channel in GSM) in Bluetooth to which radio units that are not
connected to or have not been connected to a Bluetooth piconet can
listen to system information, "find" a base station or to measure
the signal strength/quality on.
[0019] As Bluetooth is designed to replace cables or infrared links
between different electronic equipments no roaming or handover
support have been incorporated in the radio interface. As soon as a
radio unit connected to a piconet is moved outside the radio
coverage of the master, the radio unit loses its connection (the
call).
SUMMARY
[0020] A number of problems occur when local radio networks,
utilising radio interfaces that are unsynchronised with each other
and have no broadcast control channel, are to be connected into and
used as a cellular radio communication system.
[0021] A radio unit that is switched on in a local radio network
can not be attached to the system with the help of a broadcast
channel.
[0022] A radio unit that has established a link to one local radio
network can not reach or be reached from another local radio
network.
[0023] A radio unit can not roam or perform handover to a new local
radio network when it is moved outside the local radio network it
was first connected to.
[0024] The system can not measure the signal strength/quality from
and keep track of neighbouring local radio networks to be able to
perform high quality roaming and handover.
[0025] A radio node/base station from one local radio network can
not establish a link with a radio unit in a neighbouring local
radio network.
[0026] In light of the foregoing, a primary object of the present
invention is to provide methods and means for creating a cellular
radio communication system out of a number of local radio networks,
where each network utilises a radio interface that has no broadcast
channel and is unsynchronised compared to the other radio
interfaces in the system. E.g. methods and means for attaching a
radio unit to the system, retaining the connection to the system
and providing measuring, roaming and handover capabilities.
[0027] According to a first aspect of the present invention there
is a method for attaching a radio unit to a cellular radio
communication system comprising a number of local radio networks
utilising radio interfaces that are unsynchronised with each
other.
[0028] According to a second aspect of the present invention there
is a method for retaining a connection to a radio unit in a
cellular radio communication system comprising a number of local
radio networks utilising radio interfaces that are unsynchronised
with each other.
[0029] According to a third aspect of the present invention there
is a method for collecting data for a neighbouring list in a
cellular radio communication system comprising a number of local
radio networks utilising radio interfaces that are unsynchronised
with each other.
[0030] According to a fourth aspect of the present invention there
is a method for calculating the realtime clock of a first radio
node in a second radio node in a cellular radio communication
system comprising a number of local radio networks utilising radio
interfaces that are unsynchronised with each other.
[0031] According to a fifth aspect of the present invention there
is a method for co-ordinating the use of time slots in different
local radio networks in a cellular radio communication system
comprising a number of local radio networks utilising radio
interfaces that are unsynchronised with each other.
[0032] A system according to the present invention comprises a
control unit connected with a number of local radio networks and
providing the basic means of a cellular radio communication
system.
[0033] A control unit according to the present invention is
connected with a number of local radio networks to provide the
basic means for a cellular radio communication system.
[0034] An advantage with the present invention is that it is
possible to attach and retain a radio unit that is switched on in
the cellular radio communication system with no broadcast
channel.
[0035] Another advantage is that it is possible to provide roaming
and handover between local radio networks having radio interfaces
that are unsynchronised with each other.
[0036] Still another advantage is that it is possible for a radio
node in one local radio network to make a contact with a radio unit
in another neighbouring local radio network.
[0037] Yet another advantage is that the signalling in the
respective local radio network can be coordinated to facilitate
inter local radio network communication.
[0038] Still another advantage is that it is possible for the
system to keep track of neighbouring local radio networks to each
radio unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] FIG. 1 is illustrating a block diagram of a first embodiment
of a cellular radio communication system according to the present
invention
[0040] FIG. 2 is illustrating a flow chart of a first method
according to the present invention.
[0041] FIG. 3 is illustrating a flow chart of a first embodiment of
a second method according to the present invention.
[0042] FIG. 4 is illustrating an example of a BRFP_candidates list
according to the present invention.
[0043] FIG. 5 is illustrating an example of a neighbouring list
according to the present invention.
[0044] FIG. 6 is illustrating a flow chart of a second embodiment
of the second method according to the present invention.
[0045] FIG. 7 is illustrating a flow chart of a first embodiment of
a third method according to the present invention.
[0046] FIGS. 8a-b are illustrating a block diagram of a paging
scenario according to the present invention.
[0047] FIG. 9 is illustrating a flow chart of a fourth method
according to the present invention.
[0048] FIG. 10 is illustrating a flow chart of a fifth method
according to the present invention.
[0049] FIG. 11a is illustrating uncoordinated timeslots in two
local radio networks.
[0050] FIG. 11b is illustrating co-ordinated time slots in two
local radio networks according to the present invention.
[0051] FIG. 12 is illustrating a block diagram of a second
embodiment of a cellular radio communication system according to
the present invention
[0052] FIG. 13a is illustrating a schematic block diagram of a
first embodiment of a control node according to the present
invention.
[0053] FIG. 13b is illustrating a schematic block diagram of a
second embodiment of a control node according to the present
invention.
[0054] FIG. 14 is illustrating a schematic block diagram of a radio
node according to the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0055] As previously stated, the present invention relates to a
cellular radio communication system comprising a number of local
radio networks (piconets).
[0056] FIG. 1 illustrates a block diagram of a first embodiment of
a cellular radio communication system 100 for utilising the present
invention. The system 100 comprises a control-node (BCCFP) 108
connected to four radio-nodes (BRFP) 104-107 respectively. The BRFP
105 is serving two radio units (BPP) 101, 102 respectively and the
BRFP 107 is serving a radio unit (BPP) 103. The BRFP 105 and the
two BPPs 101, 102 respectively utilises a radio interface, to
enable communication between them, and forms a first piconet 109 (a
first local radio network). The BRFP 107 and the BPP 103 utilises
the same radio interface and forms a second piconet 110 (a second
local radio network). The radio interface used in piconet 109 is
not synchronised with the radio interface used in piconet 110.
[0057] The control-node 108 may be connected to a PSTN (Public
Switched Telephone Network) and/or a PLMN (Public Land Mobile
Network) as illustrated by the dashed cloud 112. The control-node
108 can also be connected to other control-nodes so as to form a
bigger cellular radio communication system than illustrated in FIG.
1. This system 100 will be described in more detail at the end of
this description.
[0058] FIG. 2 illustrates a flow chart of a first method according
to the present invention for attaching the BPP 101 to the cellular
radio communication system 100 in FIG. 1. Attaching a BPP means
that the cellular system becomes aware of that a new radio unit is
switched on in the system, where in the system the new radio unit
is located, if the new radio unit is authorised to use the system
and to registrate the new radio unit in the system.
[0059] According to a step 201, the BPP 101 establishes a link with
the BRFP 105 so that it becomes a part of the first piconet 109 in
FIG. 1. The BPP scans for BRFPs within its radio coverage area, at
regular intervals, by transmitting inquire signals (LC_INQUIRY)
including the identity and the realtime clock of the BPP 101. The
BRFPs in radio range answers by transmitting acknowledge signals
(LC_FHS.sub.BRFP) including their identity and realtime clocks to
the BPP 101. The BPP 101 can then select one of these BRFPs, in
this case BRFP 105, and transmit a page signal (LC_PAGE) to the
selected BRFP and establish the link. The BPP 101 assumes the role
as a master and the BRFP 105 takes the role as a slave. The BRFP
105 receives identification data from BPP 101, e.g. the
IEEE-identity and/or if the radio unit 101 is equipped with a
SIM-card the IMSI identity. The BRFP 105 also receives information
regarding the class of service provided by the BPP 101,
authentication, and as previously stated the realtime_clock of the
BPP 101 which is needed to calculate the frequency hopping sequence
in the BRFP 105.
[0060] The BPP 101 makes the first contact, by the LC_INQUIRY, with
the BRFP 105 before it can detect any signal from the BRFP 105. The
BRFP 105 needs to know at least the identity of the BPP 101
(received by the LC INQUIRY) to be able to transmit a signal that
the BPP 101 can detect. This is because that there is no broadcast
control channel in the radio interface utilised in the system
100.
[0061] According to a step 202, the BRFP 105 performs a Bluetooth
authentication (LMP_Bluetooth_Authentication). This is performed
between the Bluetooth circuits in the BRFP 105 and the BPP 101 in a
known way.
[0062] According to step 203, the BRFP 105 forwards the information
and the identification data received in step 201 to the BCCFP
108.
[0063] According to step 204, the BCCFP 108 identifies the BPP 101
by the identification data.
[0064] According to step 205, the BCCFP 108 authenticates the BPP
101. As an example, the known authentication technique used in GSM
can be used for this authentication. The IEEE identity with
additional authentication information can also be used.
[0065] According to step 206, the BCCFP 108 registers the identity
of the BPP 101 in the system. This means that the BPP 101 has
established a connection with the system 100 and is ready to
receive incoming calls etc.
[0066] According to a step 207, the BRFP 105 initiates a
Master-Slave switch so that the BRFP 105 becomes the master and the
BPP 101 becomes the slave.
[0067] According to step 208, the BRFP 105 puts the BPP 101 in a
parked mode by transmitting a park command. This means that the BPP
101 will terminate the link to the BRFP 105 but still be active and
listen for signals from the BRFP 105 (the master) so that it can
retain the link to the BRFP 105 again. This means that if the
maximum number of BPPs in a piconet is 7 and the BPP 101 was the
7.sup.th one a new BPP may not be able to connect to the piconet
after the BPP 101 is put in the parked mode.
[0068] FIG. 3 illustrates a flow chart of a second method according
to the present invention for retaining the connection to the BPP
101 in the cellular radio communication system 100 in FIG. 1 after
the BPP 101 has been attached to the system.
[0069] According to a step 301, the BRFP 105 (the master)
establishes a beacon signalling to the BPP 101 (the slave) at
evenly spaced time instants (beacon intervals). This means that the
BPP 101 receives signals from the BRFP 105 at the beacon
intervals.
[0070] This beacon signal can as an example comprise parameters
that activates a parked slave (e.g. a channel access code for the
BPP 101), re-synchronises parked slaves or allows certain slaves to
access the channel. This signal can as an alternative also include
information regarding how busy the BRFP 105 is. The beacon signal
is transmitted to a number of specific radio units, in this case
the BPP 101, and not to all radio units within radio range of the
radio node as with a broadcast channel. The beacon signal is
intended as a means for a master to retain the link to slaves that
are not active in any transmissions and if needed to activate
parked slaves (see step 208 above).
[0071] If, according to a step 302, the BPP 101 is in a parked mode
the method continues with step 303, otherwise it 30 continues with
step 304.
[0072] According to a step 303, the BRFP 105 activates the parked
BPP 101 by transmitting a page with the identity of the BPP 101.
This can be made at evenly spaced time instants.
[0073] According to a step 304, the BPP 101 measures a signal
parameter, e.g. the signal quality or signal strength, on the
beacon signal from BRFP 105. The BPP 101 transmits this measurement
to the BRFP 105 in a result signal.
[0074] According to a step 305, the BRFP 105 measures the signal
parameter on one or more signals from the BPP 101, e.g. the result
signal in step 304. The BRFP 105 forwards the measurements in step
304 and 305 to the BCCFP 108 which stores them in a BRFP_candidates
list. See FIG. 4 which illustrates an example of such a list. The
BRFP 105 puts the BPP 101 in parked mode again if the BPP 101 where
in a parked mode in step 302.
[0075] According to step 306, the BCCFP 108 checks if there is a
neighbouring list for the BRFP 105 stored in the BCCFP. If not, the
method continues with step 701 according to FIG. 7 for creating
such a list. The neighbouring list for BRFP 105 comprises
information of which additional BRFPs in the system that a BPP
connected to BRFP 105 in piconet 109 should be able to hear. FIG. 5
shows an example of such a neighbouring list for BRFP 105 where
BRFP 104 and 106 are listed as neighbours.
[0076] According to step 307, the BCCFP 108 orders the BRFPs 104
and 106 in the neighbouring list to page the BPP 101, activate the
BPP if needed, establish a beacon signalling and perform
measurements according to step 301-305. If a BRFP on the
neighbouring list is unable to establish a link to the BPP 101 (the
BPP 101 may temporarily be out of reach) it will continue to page
the BPP 101 as long as the BPP 101 remains in the piconet 109
associated with the BRFP 105. The BRFPs 104 and 106 on the
neighbouring list can page (reach) the BPP 101 thanks to the BCCFP
108 which distributes the identity of the BPP 101 to the BRFPs.
[0077] The three BRFP 104, 105 and 106 respectively will now have
beacon signalling ongoing with the BPP 101. The BRFP 104, 106
respectively will measure one or more signal parameters, e.g. the
signal quality and/or signal strength, from the BPP 101 whenever
they have free capacity for that. As an alternative, if the BPP 101
is in a parked mode, one BRFP, e.g. BRFP 105, can activate the BPP
101, receive measurements from the BPP and deactivate the BPP
within a short interval and the other BRFPs, e.g. BRFP 104 and 106,
can do the same but within a longer interval to reduce the
signalling within the system. If this is the case, the BPP may
perform measurements on the BRFPs 104 and 106 at the same time as
on the BRFP 105 and transmit these measurements to the BRFP 105 at
the shorter intervals.
[0078] FIG. 6 illustrates a flow chart of a second embodiment of
the second method where the measurements in step 304 and 305 are
made during an ongoing call. This means that step 304 and 305
according to FIG. 3 may be replaced by the following steps.
[0079] According to a step 601, the BRFP 105 transmits information
to the BCCFP 108 regarding the exact clock information and hop
sequence used for the call/link to the BPP 101.
[0080] According to a step 602, the BCCFP 108 forwards the
information received in step 601 to the BRFP 104 and 106, i.e. to
all additional BRFPs on the neighbouring list for BRFP 105.
[0081] According to a step 603, the BRFP 104 and 106 measures the
signal strength and/or signal quality on the ongoing call between
the BRFP 105 and the BPP 101, e.g. in a separate receiver in the
BRFPs dedicated for monitoring (e.g. measuring).
[0082] According to a step 604, the BRFP 104 and 106 transmits the
measured signal strength and/or signal quality to the BCCFP 108
which stores these measurements in the BRFP_candidates list for the
BRFP 105.
[0083] The steps 601-604 may in a third embodiment of the second
method (not illustrated) be used as a complement to step 304 and
305 instead of replacing them. This means that steps 601-604 are
performed after step 607 in FIG. 3.
[0084] If the link between the BPP 101 and the BRFP 105 becomes bad
the second method may continue to perform roaming as the described
below (not illustrated in any flow charts).
[0085] The link roams from BRFP 105 to BRFP 104 that, according to
the BRFP_candidates list for BRFP 105, has the best signal strength
and/or signal quality for the moment (see FIG. 4). This means that
the BCCFP 108 selects the new BRFP for roaming with the help of the
BRFP_candidates list. This selection may as an alternative or as a
complement be made on free capacity in the neighbouring BRFPs.
[0086] If the BPP 101 does not respond to any signalling from the
BRFP 104, e.g. a page signal, the second method may end by
unregister the BPP 101 as described below (not illustrated in any
flow chart).
[0087] The BRFP 104 transmits an unregistered message (UNREG) to
the BCCFP 108 regarding a link loss to the BPP 101.
[0088] The BCCFP 108 controls if any other BRFP, e.g. BRFP 105 and
106, have an ongoing beacon signalling to the BPP 101. This is made
e.g. by checking the BRFPs on the neighbouring list. The BCCFP 108
unregisters the BPP 101 in the system (all links lost to BPP 101)
if no BRFP in the system has an ongoing beacon signalling to the
BPP 101.
[0089] If a system initiated handover is to be performed, the
second method may continue with a handover as described below (not
illustrated).
[0090] The BCCFP 108 selects a new BRFP from the neighbouring list
of the BRFP 104 and orders the selected BRFP, e.g. the BRFP 105, to
initiate a handover.
[0091] If a BPP initiated handover is to be performed, the second
method may continue with a handover as described below (not
illustrated).
[0092] The BPP 101 establishes a new link with the BRFP 105 which,
according to the BRFP_candidates list for BPP 101, has the highest
signal strength and/or signal quality.
[0093] The BRFP 105 orders the BCCFP 108 to route the call to the
BRFP 105. Hence both BRFP 104, 105 respectively are connected to
the BPP 101 for a short moment.
[0094] The BRFP 105 initiates a termination of the link from the
BRFP 104 to the BPP 101 when the new link is established. This is
made via the BCCFP 108.
[0095] FIG. 7 illustrates a flow chart of a third method according
to the present invention for collecting data for a neighbouring
list for the respective BRFP in the system used e.g. in the second
method above. The collected data is used for creating and updating
the neighbouring lists for the respective BRFP. As previously been
stated, the neighbouring list for the BRFP 105 comprises
information of which additional BRFPs in the system that the BPP
101 in piconet 109 can hear. This can e.g. be performed when a new
system is run for the first time, when new BRFPs are added to the
system, at specified intervals, or when one or several BRFPs are
moved to a new location within the system.
[0096] According to a step 701, all BRFPs in the system 100
transmits a page signal (LC_PAGE) to the BPP 101, see FIG. 8a. The
BRFPs have been given the identity of the BPP 101 from the BCCFP
108 which also may initiate this step.
[0097] According to a step 702, the BPP 101 transmits a
response-signal (BRFP_same_time list) to the BRFP 105. The
response-signal comprises information regarding which BRFP the BPP
101 can hear (e.g. detected a page signal from) at the same time
and, as an alternative, also the signal strength on the detected
page signal (LC_PAGE). This response signal may be transmitted each
time a new BRFP has established beacon signalling with the BPP 101
(e.g. in step 307).
[0098] According to a step 703, the BRFP 105 forwards the
information received in step 702 to the BCCFP 108. The BCCPF 108
collects this information and creates the neighbouring list for the
BRFP 105 by registrating the BRFPs (except the BRFP 105) that the
BPP 101 have heard in step 702 as neighbours to the BRFP 105 or if
such a list already exists updates the neighbouring list
accordingly. This can as an. example be made by adding "new"
neighbouring BRFPs, included in the response signal (BRFP_same_time
list) but not registrated in the neighbouring list, and deleting
"old" neighbouring BRFPs, registrated in the neighbouring list but
not included in the response signal. A delay may be used for the
deletion of BRFPs in the neighbouring list to avoid deletion of
BRFPs that are just temporarily out of reach for the page. As an
example, a certain BRFP on the list must be excluded from two or
more consecutive response signals received according to step 702
before being removed from the neighbouring list.
[0099] The BCCFP 108 can now direct signals to the BRFP serving a
specific BPP in the system and its neighbouring BRFPs, e.g. for
page signals, with the help of the neighbouring list which reduce
the signalling within the system as seen in FIG. 8b. This improves
the performance of the system.
[0100] FIG. 9 illustrates a flow chart of a fourth method according
to the present invention where the realtime clock of a BRFP in one
piconet is calculated by a BRFP in another piconet, e.g. the
realtime clock of BRFP 105 is calculated by the BRFP. 106, see FIG.
1. This method is preferably performed when more than one BRFP
(from different piconets) have established a link with one and the
same BPP. In the steps below both the BRFP 105 and the BRFP 106 in
the system 100 have established a link with the BPP 102.
[0101] According to a step 901, the BRFP 105 calculates a first
realtime_clock difference value (.DELTA.1_CLOCK) between the BPP
102 and its own realtime_clock
(clock_BPP.sub.102-clock_BRFP.sub.105).
[0102] According to a step 902, the BRFP 105 transmits the
calculated .DELTA.1_CLOCK value to the BCCFP 108 which stores it in
a sync-list or as an alternative in the neighbouring list.
[0103] According to a step 903, the BRFP 106 calculates a second
realtime_clock difference value (.DELTA.2_CLOCK) between the BPP
102 and its own clock (Clock_BPP.sub.102-Clock_BRFP.sub.106).
[0104] According to a step 904, the BRFP 106 transmits the
calculated .DELTA.2_CLOCK value to the BCCFP 108 which stores it in
the sync-list. As an alternative, the BCCFP 108 can distribute
.DELTA.1_CLOCK and .DELTA.2_CLOCK values to the BRFPs 104, 106 and
107.
[0105] According to step 905, the BCCFP 108 calculates the
BRFP_realtime_clock difference value (.DELTA.3_CLOCK) between the
BRFP 106 and the BRFP 105 (Clock_BRFP.sub.106-Clock_BRFP.sub.105)
according to the following equation:
.DELTA.3_CLOCK=.DELTA.1_CLOCK-.DELTA.2_CLOCK=[Clock_BPP.sub.102-Clock_BRFP-
.sub.105]-[Clock_BPP.sub.102-Clock_BRFP.sub.106]=-Clock_BRFP.sub.105+Clock-
_BRFP.sub.106=Clock_BRFP.sub.106-Clock_BRFP.sub.105
[0106] The .DELTA.3_CLOCK value is stored in the sync-list.
[0107] If, according to a step 906, the BCCFP wants the BRFP 106 to
establish a link to the BPP 101 in the neighbouring piconet 109,
e.g. establish beacon signalling according to step 305, the method
continues with step 907 below, otherwise it ends.
[0108] According to step 907, the BCCFP 108 transmits the
.DELTA.3_CLOCK value to the BRFP 106 and orders the BRFP 106 to
transmit an LC_PAGE to the BPP 101.
[0109] According to a step 908, the BRFP 106 calculates the
realtime clock of the BRFP 105 (Clock_BRFP.sub.105) to which the
BPP 101 is listening, e.g. during park or active mode.
[0110] Every BPP in a piconet uses the master clock (e.g. a BRFP
clock) to track the common hopping channel in the piconet when the
BPPs have assumed the roles as slaves. Hence if the master clock in
a current piconet is known, the BPP in the current piconet can be
easily reached from other BRFPs or BPPs outside the current piconet
as long as they are within radio reach. The Clock_BRFP.sub.105 is
calculated according to the following equation:
Clock_BRFP.sub.105=.DELTA.3_CLOCK-Clock_BRFP.sub.106=Clock_BRFP.sub.106-Cl-
ock_BRFP.sub.105-Clock_BRFP.sub.106=Clock_BRFP.sub.105
[0111] According to step 909, the BRFP 106 transmits an LC_PAGE to
the BPP 101 and establishes a new link and a new piconet with the
BPP 101.
[0112] The calculation in step 905 can as an alternative be made in
the BRFP 106 as well as the calculation in step 908 if the BCCFP
108 transmits the information regarding the BRFP_realtime
differences that is stored in the sync-list to the BRFP 106.
[0113] In short, all the BRFPs in the cellular radio communication
system calculates the realtime_clock differences between the BPPs
they are connected to and their own realtime clocks. The BRFPs
transmits the realtime_clock differences to the BCCFP 108 where
they are used for calculating the BRFP_realtime_clock differences
between each BRFP in the system. A first BRFP associated with a
first piconet can then page a second BPP in a second piconet (e.g.
to establish a new piconet) very accurately and quickly with the
help of the BRFP realtime_clock difference as described in step
908.
[0114] FIG. 10 illustrates a flow chart of a fifth method according
to the present invention for co-ordinating the use of timeslots in
-each piconet associated with the cellular radio communication
system. This method is preferably performed when a call is in
progress on a link in a piconet and hence one available time slot
is occupied.
[0115] According to a step 1001, the BRFPs 104-107 in the system
100 calculates the realtime_clock differences between the BPPs they
are connected to and their own realtime clocks as in step 901 and
903 according to FIG. 9.
[0116] According to a step 1002, the BRFPs 104-107 transmits the
calculated realtime_clock differences to the BCCFP 108, as in step
902 and 904 according to FIG. 9.
[0117] According to a step 1003, the BCCFP 108 calculates the
BRFP_realtime_clock differences between the BRFP 104-107, as in
step 905 according to FIG. 9, from the realtime_clock differences
received in step 1002.
[0118] According to a step 1004, the BCCFP 108 selects the
realtime_clock of BRFP 104 as a reference clock (ref_clock) for all
piconets in the system 100. This can as an example be made by
giving the first slot from BRFP 104 the time value 0 whereby the
other BRFPs are given an offset value according to their
BRFP_realtime_clock difference with BRFP 104 which are e.g. added
to or subtracted from their own realtime clocks.
[0119] According to a step 1005, the BCCFP 108 orders all BRFPs in
the system 100 to use, as long as possible, a time slot
co-ordinated with the ref_clock for signalling and payload to their
respective BPP.
[0120] This means that the signalling in the system 100 can be made
more effective by increasing the probabilities of a fast connection
set-up between BPPs and BRFP in different piconets, since blocked
time slots (blind_spots) will be more rare. Further on the total
system capacity will increase.
[0121] FIG. 11a illustrates uncoordinated traffic and signalling in
piconet 109 and 107 in system 100. There are three timeslots, each
with a transmit portion and a receive portion, on the hopping
channel in each piconet that the BPPs and BRFPs can use. BRFP 105
and BPP 101 communicates on the first timeslot and BRFP 105 and BPP
102 communicates on the second timeslot in piconet 109, which means
that the third timeslot in piconet 109 is free. BRFP 107 and BPP
103 communicates on the third timeslot in piconet 110, which means
that the first and second timeslot in piconet 110 are free. If BRFP
107 wants to page BPP 102 in piconet 109, the BRFP 107 has to use
the first or second timeslot in piconet 110 (the free ones) but the
corresponding timeslots in piconet 109 are not free. This means
that the BRFP 107 can not reach the BPP 102 right know and have to
wait until the communication on the first or second timeslot in
piconet 109 stops. Hence two blind_spots 1101 and 1102 have
occurred.
[0122] FIG. 11b illustrates the same traffic and signalling as in
FIG. 11a but co-ordinated according to the fifth method (FIG. 10).
The realtime clock of the BRFP 105 is selected as the ref_clock and
the BRFP 107 has co-ordinated its traffic to BPP 103 accordingly so
that the BPP 102 can be reach by a page P from the BRFP 107 in the
third timeslot. The third timeslot in BPP 102 is synchronised with
the third timeslot in BRFP 107 by introducing a small pause 1103
between the second and third timeslot in BPP 102. This means that a
part of the space where the next timeslot in BPP 102 (the first one
due to the three time slot scheme) where to be put is used for the
third timeslot. The first timeslot can therefore not be used for
the moment. As seen in FIG. 11b the BRFPs in the respective piconet
are still not synchronised to each other.
[0123] The inventive methods according to FIGS. 2, 3, 6, 7, 9 and
10 can be completely or partially implemented as software in at
least one microprocessor.
[0124] As previously been described, FIG. 1 illustrates a block
diagram of a first embodiment of a cellular radio communication
system 100 for utilising the present invention. The BRFPs in FIG. 1
are connected to the BCCFP 108 via a local area network (LAN)
111.
[0125] FIG. 12 illustrates an alternative connection where each
BRFP is circuit switched connected to a switch 1201, preferably
arranged in the BCCFP 108, via dedicated transmission lines. The
BRFPs can as another alternative be connected to the BCCFP 108 via
one or more radio links, e.g. a radio-LAN or wireless-LAN
(WLAN).
[0126] Each BRFP and BPP comprises at least one Bluetooth
circuit/chip for utilising the radio communication over the
Bluetooth radio interface. The Bluetooth radio interface is one
example of a radio interface utilised in small short range local
radio network. Other radio interfaces with similar characteristics
may also be used.
[0127] The system 100 can as an example be an indoor cellular radio
communication system where the first piconet 109 is situated in a
first room and the second piconet 110 is situated in a second room.
The BRFPs 1.05 and 107 can as an example be personal computers
(PCs) with means for radio communication and connected to the LAN
111. The BPP 101 can as an example be a cordless phone, the BPP 102
a laptop with means for radio communication and the BPP 103 a
printer with means for radio communication. The BRFP 106 may be a
phone situated in a third room and connected to the LAN by wire. If
the BPP 101 is moved to the third room the BRFP 106 and the BPP 101
establishes a connection and hence forms a new (third) piconet.
[0128] A complete cellular radio communication system needs to have
some basic functionality's to work and reach an acceptable system
behaviour. Those are described in the methods according to FIGS. 2,
3, 6, 7, 9 and 10.
[0129] All these basic functionality's are provided in the cellular
radio communication system 100 according to the present invention.
This is achieved by the BCCFP 108 (the control node) connected to
all BRFPs in the system 100.
[0130] FIG. 13a illustrates a schematic block diagram of a first
embodiment of a BCCFP 1301 (control node) according to the
present-invention. The BCCFP 1301 comprises a processor with a
memory 1302, a hard disk 1303 and a network interface 1304
connected to each other by a computer bus 1305. The processor with
the memory is e.g. used for creating and updating the neighbouring
lists and calculating realtime clock differences. The hard disk is
e.g. used for storing the neighbouring lists, realtime clock and
identity information. The network interface 1304 is used for
connecting the BCCFP to the BRFPs via a LAN 1306. All voice and
data traffic is separated from the BCCFP in this embodiment and
hence processed by a separate voice/data unit 1307 connected to the
LAN 1306.
[0131] FIG. 13b illustrates a schematic block diagram of a second
embodiment of a BCCFP 1308 according to the present invention where
the voice/data unit 1307 is integrated in the BCCFP 1308. The
voice/data unit 1307 comprises a voice codec and means for
conversion between circuit switched and packet switched
information.
[0132] FIG. 14 illustrates a schematic block diagram of a BRFP 1401
(radio node) according to the present invention. The BRFP comprises
a processor with a RAM memory and a flash memory 1402, a bluetooth
radio interface chip/unit 1403 and a network or serial
communication interface 1404 connected to each other by a computer
bus 1405. The processor with the RAM memory and flash memory is
e.g. used for processing and distributing realtime clock
information. The bluetooth radio interface chip/unit has previously
been described. The network interface is used for connecting the
BRFP to a LAN according to FIG. 1 and the serial communication
interface is used if the BRFP is circuit switched connected
according to FIG. 12.
* * * * *