WI-LAN Inc. v. Alcatel-Lucent USA Inc. et al

Filing 182

REPLY to 167 Claim Construction Brief,,,,, filed by WI-LAN Inc.. (Attachments: # 1 Affidavit Declaration of Jeffrey T. Han, # 2 Exhibit I - true and correct copy of U.S. Patent No. 5,603,095, # 3 Exhibit II - true and correct copy of U.S. Patent No. 5,239,682, # 4 Exhibit III - true and correct copy of U.S. Patent No. 5,659,598., # 5 Exhibit IV - true and correct copy of WO 96/37054., # 6 Exhibit V - true and correct copy of Sanford Bingham, Multiplexers, Computerworld, Nov. 27, 1989, at 61., # 7 Exhibit VI - true and correct copy of David J. Stang, Network)(Weaver, David)

EXHIBIT III

~IIIIIIIIIIII
US005659598A

II
United States Patent

[19]

[11]

Byrne et al.
[54]

[45]

Patent Number:
Date of Patent:

5,247,701
5,260,988
5,278,991
5,392,331
5,454,028

DUAL MODE SUBSCRIBER TERMINAL AND
A HANDOVER PROCEDURE OF THE DUAL
MODE SUBSCRIBER TERMINAL IN A
MOBILE TELECOMMUNICATION
NETWORK

9/1993
11/1993
111994
211995
9/1995

5,659,598
Aug. 19, 1997

Comroe et aI ......................... 455133.4
Schellinger et aI. ...................... 379159
RamsdaIe et aI ...................... 455133.2
Patsiokas et aI .......................... 379/60
Hara et aI ................................. 379/61

FOREIGN PATENI' DOCUMENTS
[75]

Inventors: Jolm Byxne, Shepperton, Great Britain;
Teuyo Jineli, Helsinki; Sanna
Maenpia, Espoo, both of Finland

[73]

Assignees: Nokia Telecommunications Oy, Espoo;
Nokia Mobile Phones Limited, Salo,
both of Finland

[21]

Appl. No.:

454,131

[22]

PCf Filed:

Oct 6,1994

[86]

PCf No.:

PCTIFI941OO447

§ 371 Date:

Jun. 8, 1995

PCf Pub. No.: W095110922

Foreign Application Priority Data

Oct. 8, 1993

[51]
[52]
[58]

[GB]

United Kingdom ................ 9320814.8

6

Int. CI. ............................. H04M 11/00; H04Q 7/38
U.S. CI............................ 455/436; 455/426; 455/553
Field of Search .................................. 379/60. 59, 58;
455/33.2, 33.4

References Cited

[56]

u.s. PATENr DOCUMENTS
4,893,327
5,127,042

ABSTRACT

A dual mode terminal is provided. in which a mobile station
of a mobile radio system and a cordless telephone are
combined. This kind of terminal may have a connection with
both a base station of the mobile radio system and a fixed
part of the cordless telephone system. Handover may imply
the transfer of a call from a fixed part of the cordless
telephone system having a terminal-initiated handover to a
base station of the mobile radio system having a networkinitiated handover. In order to carry out a proper handover
procedure, the cordless telephone part obtains from the
mobile station part of the terminal measurement results
relating to received signal strengths of the mobile system
base stations in the neighborhood. The cordless telephone
part of the terminal forwards these measurement results via
a fixed part of the cordless telephone system to the mobile
exchange of the mobile system in a handover request
message. The mobile exchange selects a proper base station
for handover and informs the mobile station part of the
terminal about the identity of the selected base station via the
cordless telephone part.

111990 Stem et aI. ........................ 455/33.1 X
6/1992 Gillig et aI. . ............................. 379159

PP MS

5 Claims, 2 Drawing Sheets

FP

1)IMM INFO REQ

,

-

. __ MM INFO ACCEPT
... 7) HID ACCESS
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MS(

BSS

2) OM HID REQ

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9) HID (OM

United Kingdom.
WIPO.

Primary Examiner-Dwayne Bost
Assistant Examiner-5cott Richardson
Attome~ Agent, or Firm-Cushman, Darby & Cushman
Intellectual Property Group of Pillsbury, Madison & Sutro
[57]

PCf Pub. Date: Apr. 20, 1995

[30]

5/1990
8/1993

LLP

§ 102(e) Date: Jun. 8, 1995
[87]

2225512
9316549

6)

3)
_H/O REQ
-H/O ACK
I OM HID CMD S}

I

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8)

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PHYS INFO
10)

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11)

WIL-0192832

u.s. Patent

Aug. 19, 1997

5,659,598

Sheet 1 of 2

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WIL-0192833

u.s. Patent

21

5,659,598

Sheet 2 of 2

Aug. 19, 1997

PP

MS

20

CONTROL

22

23

UNIT

FIG. 2

pp

MS·~

MS(

BSS

FP

1)1MM INFO REQ
2) OM HID REQ

_H/O REQ

4)
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... 7) HIO ACCESS

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FIG. 3

W1L-0192834

5,659,598
1

2

telephone system to a base station of a mobile telecommunications system.
One aspect of the invention is. in a mobile telecommunications system including a fixed network comprising
5 mobile exchanges, first base stations connected to the
mobile exchanges. and second base stations of a cordless
BACKGROUND OF THE INVENITON
telephone system, the second base stations being connected
to and under control of the mobile exchanges. dual mode
The invention relates to a mobile telecommunications
subscriber terminals having a mobile station part for radio
system including a fixed network comprising mobile
exchanges. base stations for mobile stations, and cordless 10 communication with said first base stations and a cordless
telephone part for radio communication with the second
telephone base stations connected to and under control of the
base stations; a method for performing handover from one of
mobile exchanges. In particular, the present invention relates
the second base stations to one of the first base stations.
to a method for performing handover from the cordless
comprising the steps of:
telephone base stations to base stations for mobile stations.
measuring field strengths of said first base stations at the
Conventional cordless telephones operate as an extension 15
mobile station part of the dual mode terminal and storing
to the Public Switched Telephone Network (PSTN). A
measurement results,
cordless telephone system consists of a portable handset and
a base station (a fixed part) connected to PSTN. The first
detecting low quality of connection between one of the
cordless telephone systems were analog systems, such as 20 second base stations and the cordless telephone part of the
cn. Recently digital cordless telephone systems, such as dual mode terminal during an on-going call.
CI'2 and DEC!' (Digital European Cordless Telephone)
obtaining the stored measurement results from the mobile
have been introduced. When a cordless telephone is a
station part to the cordless telephone part of the dual mode
subscriber of PSTN, a cordless telephone is accessed by
terminal,
dialing the telephone number associated with the fixed
sending a message including the obtained measurement
subscriber connection to which the base station is connected. 25 results and terminal identity to the one of the second bas~
Also, the subscriber has access to the PSTN only via the
stations by the cordless telephone part of the dual mode
home base station. In C!'2 and DEC!', also a telepoint
terminal.
service is introduced, whereby a subscriber to the service
can make calls away from home via a public base station.
sending a handover request message from the one of the
Also. a common air interlace for cordless telephones was 30 second base stations to one of the mobile exchanges in
response to receipt of the message including the measureintroduced to facilitate roaming between systems and so to
improve service coverage for the use.
ment results. the handover request message including the
terminal identity and the measurement results.
There has also been a proposal to combine a cordless
selecting one of the first base stations on the basis of the
telephone system with a cellular mobile telecommunications 35
measurement results.
system to further improve the roaming capabilities by means
of utilization of the mobility control of the cellular network.
sending a handover command message to the one of the
When combined with the mobile telecommunications
second base stations from the one of the mobile exchanges,
systems, the roaming of the cordless telephone handsets
the message including the information of the selected one of
within the cordless telephone systems is fully supported. 40 the first base stations.
However. the cordless telephone handset is not able to utilize
sending a message to the cordless telephone part of the
the more extensive radio coverage of the supporting cellular
dual mode terminal from the one of the second base stations.
network or to perform handover to or from the cellular
the message including information of the selected one of the
network. This disadvantage is due to several reasons.
first base stations.
forwarding the information of the selected one of the first
Firstly, the radio interfaces of cordless telephone systems 45
and the mobile radio systems are usually incompatible.
base stations to the mobile station part from the cordless
Secondly, the handover procedures are different. In cordtelephone part of the dual mode terminal,
less telephone systems, the handover procedure is usually
establishing a connection between the mobile station part
of the dual mode terminal and the selected one of the first
initiated by the portable terminal. More particularly, when a
cordless telephone tenninal considers it necessary to change 50 base stations,
from one base station to another. the terminal scans the
releasing the connection between the cordless telephone
frequency band and selects the appropriate base station for
part of the dual mode terminal and the one ofthe second base
the handover. In most of the mobile telephone systems, the
stations.
handover is controlled by the network. The mobile station
Another aspect of the invention is a mobile telecommuonly measures the quality of the radio connection and 55 nications system including a fixed network comprising:
mobile exchanges. first base stations connected to the
forwards the measuring results to the fixed network. One of
the network elements, for example a mobile exchange,
mobile exchanges and second base stations of a cordless
telephone system, the second base stations being connected
makes a decision for handover on the basis of the obtained
information.
to and under control of the mobile exchanges; a dual mode
60 subscriber terminal comprising
SUMMARY OF THE INVENITON
a mobile station part for radio communication with the
first base stations,
It is an object of the invention to provide a subscriber
a cordless telephone part for radio communication with
terminal capable of communicating with both a fixed part of
the second base stations.
a cordless telephone system and a base station of the mobile
radio system.
65
means for measuring field strengths of the first base
It is a further object of the invention to provide a method
stations at the mobile station part of the dual mode terminal
for performing handover from a fixed part of a cordless
and storing measurement results,

DUAL MODE SUBSCRIBER TERMINAL AND
A HANDOVER PROCEDURE OF THE DUAL
MODE SUBSCRIBER TERMINAL IN A
MOBILE TELECOMMUNICATION
NETWORK

WIL-0192835

5,659,598
3

4

means for monitoring quality of connection between one
of lhe second base stations and lhe cordless telephone part
of the dual mode terminal during an ongoing call,
means for requesting lhe stored measurement results from
lhe mobile station part to lhe cordless telephone part of the
dual mode terminal in response to detecting low quality of
the connection,
means for sending a message including the obtained
measurement results and a terminal identity to the one of the
second base stations from the cordless telephone part of the
dual mode terminal,
means for receiving a message at the cordless telephone
part of the dual mode terminal from the one of the second
base stations, the message including information on the one
of the first base stations which is selected for handover,
means for forwarding the information of the selected one
of the first base stations to the mobile station part from the
cordless telephone part of the mode terminal so as to
establish a connection between the mobile station part of the
dual mode terminal and lhe selected one of the first base
stations.
In the invention, a dual mode terminal is utilized, in which
a mobile station of a mobile radio system and a cordless
telephone are combined. This kind of terminal can have a
connection with both a base station of the mobile radio
system and a fixed part of the cordless telephone system.
Handover in the case of this dual mode terminal can imply
the transfer of a call from a fixed part of the cordless
telephone system to a base station of the mobile radio
system. As noted before, the primary problem in this concept
is that two systems utilizing different handover principles
are combined. In the cordless telephone systems, such as
DEer, handover is a terminal controlled procedure and the
terminal will make a decision when the handover is needed.
In the mobile radio system, such as GSM, the network will
always decide when to perform a handover.
In the present invention, the cordless telephone part of the
dual mode terminal will initiate the handover procedure
from a cordless telephone system to a mobile radio system,
when the cordless telephone part of lhe dual mode terminal
recognizes that the quality of connection is getting worse
and the mobile radio system could offer a better connection.
In order to carry out a proper handover procedure, the
cordless telephone part obtains, from the mobile station part
of the terminal, measurement results relating to received
signal strength of the mobile system base stations in lhe
neighborhood. The cordless telephone part of the terminal
forwards these measurement results via a fixed part of the
cordless telephone system to the mobile exchange of the
mobile system in a handover request message. The mobile
exchange selects a proper base station for a handover and
informs the cordless telephone part of the terminal about the
identity of the selected base station via the fixed part of the
cordless telephone system. The cordless telephone part of
the terminal fOlWards the identity of the base station to the
mobile station part of the terminal which initiates an establishment of a connection with lhe selected base station. After
the establishment of the connection is completed, the mobile
station part informs the cordless telephone part about the
matter and the latter releases the radio path of the cordless
telephone system. Thus. the invention allows a terminalinitiated handover from a cordless telephone system to a
mobile system which utilizes a network-initiated handover
procedure.

FIG. 1 shows a general diagram of a mobile radio system
which supports a cordless telephone system.
FIG. 2 shows a general diagram of a dual mode subscriber
terminal according the invention, and
FIG. 3 is a signalling diagram for the handover method
according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS
The description of the preferred embodiments of the
invention will now be made with reference to the attached
drawings, in which

5

DETAll..ED DESCRIPTION
10

15

20

25

30

35

40

45

50

55

60

65

In the following, the invention will be described using a
digital 84 cellular radio system known as GSM (Groupes
Speciale Mobile) as an example of the mobile radio system,
and DECf (Digital European Cordless Telephone) as an
example of cordless telephone systems. However, the invention is not intended to be restricted to these systems. The
invention may be applied to any mobile radio system.
FIG. 1 shows the functional environment of a GSMI
DECf dual mode terminal. In HG. 1, both base stations BSS
of the GSM system and fixed parts FP of the DECT system
are connected to the GSM mobile exchange MSC. One of
the DECT fixed parts FP is shown to be connected to the
private branch exchange PBX which is further connected to
the MSC. The MSC may be connected to other MSCs, a
PSTN (Public Switched Telephone Network) or an ISDN
(Integrated Services Data Network). The MSC is also connected to the visitor location register VLR, which is a data
base maintaining subscriber mes on the subscribers visiting
in the area of the MSC, and to a home location register HLR
which is a data base maintaining subscriber mes on all the
subscribers in the system, and further to an authentication
center AC and to an equipment identity register ElR. For a
more detailed description of the operation and structure of
the GSM system, reference is made to GSM specifications
and to a book "The GSM system for mobile
communication", M. Mouly and M. Pautet, Palaiseau,
France, ISBN:2 9507190-0-7.
FIG. 2 shows a general view of a GSMIDECT dual mode
subscriber terminal according to the invention. The terminal
20 consists of a GSM mobile station part MS 21 and a DECT
portable terminal part PP 22. The GSM part of the dual mode
terminal MS is used when communicating with GSM base
stations. The DECT part PP of the dual mode terminal is
used when communicating with DECT fixed parts FP. Both
MS and PP include all the necessary equipment, such as
radio transceivers, for signalling and communicating over
the respective radio interface. It is normally advantageous to
embody at least some functions and circuits, such as display,
keyboard, power supply. etc., by means of a common
circuitry. In HG. 2, a common control unit 23 is connected
to the MS and PP parts of the dual mode terminal for
controlling the operation thereof.
The GSM network provides a full mobility management
support for the cordless telephone systems connected to it.
Thus, the GSM network maintains mes on the cordless
telephone subscribers and the current location thereof and is
therefore able to route the calls addressed to the cordless
telephone to their current locations. Basically, the cordless
telephone subscribers are handled in a similar manner with
the ordinary GSM subscribers.
Thus, the dual mode terminal according to the invention
is capable of communicating with both GSM base stations
and DECf base stations (fixed parts) FP. Consequently, a
dual mode terminal should also be able to roam anywhere in
the system. However, problems are encountered when the
handover from a DECT fixed part (or vice versa) is required,
since in the DECT system handover is a terminal controlled
procedure and the terminal will make a decision when the

WIL-0192836

5,659,598
5
handover is needed. In the GSM system, the network will
always decide when to perform a handover.
An example of the handover procedure according to the
invention from a DECf fixed part to the GSM base station
will be described in the following with reference to FIG. 3.
Firstly, it is assumed that the cordless telephone part PP of
the dual mode terminal has a DECf connection and is
engaged in an on-going call via the fixed part FP of the
DECT system. The mobile station part MS of the dual mode
terminal is simultaneously measuring the signal strength of
the neighboring GSM base stations and stores the measurement results.
In step 1 of FIG. 3, when detecting during the call that the
quality of connection is getting worse, the PP will start a
handover JXocedure from the DECf system to the GSM
system. Firstly, the FP will request the stored measurement
results from the MS part of the terminal. After obtaining the
measurement results. the handover procedure is initiated by
sending a MM INFO REQuest message according to the
DECT common interface specification (DECf CI) from the
PP part of the terminal to the DECf fixed part FP. This
message will carry the obtained measurement results in
IWU-TO-IWU parameter. The message includes also a
portable identity.
In step 2 of FIG. 3, when the DECf fixed part FP receives
the MM-INFO-REQ message fromPP part of the dual mode
terminal, it will send a DM HlO REQuired message according to DSS.l+ JXotocol to the mobile exchange MSC. The
DSS.l+protocolis the DSS.lprotocol enhanced with mobility management. This message includes the following information elements: Portable identity, a Cause field including
information of the dual mode handover, and an IWU-TOIWU parameter including the measurement results.
In step 3 of FIG. 3, the MSC receives the measurement
results in the DM HlQ REQ message from DECf fixed part
FP. The MSC decides on the basis of the measurement
results to which GSM base station BSS it should perform the
handover. The MSC sends a HlO REQ message according to
specification GSM 08.08 to a base station BSS it has
selected for handover, to indicate that the dual mode terminal is to be handed over to that GSM base station BSS.
In step 4 of FIG. 3, HlO ACK message according to the
specification GSM 08.08 is sent from the selected GSM base
station BSS to the MSC. This message indicates that the
request to support a handover at the selected BSS can be
supported by this BSS. The message further indicates to
which radio channel the dual mode terminal should be
directed.
In step 5 of FIG. 3, the MSC sends a DM HlO CMD
message according to DSS.l + protocol to the DECT fixed
part FP to indicate that a handover procedure is available.
Also, the information of the selected GSM base station BSS
is included. Thus, the message includes the following information elements: a portable identity and a BSS identity.
In step 6, the DECf fixed part FP sends to the cordless
telephone part PP of the dual mode terminal a MM INFO
ACCEPT message according to DECf CI. This message
includes information of the selected GSM base station BSS
where handover should be done. Thus, this message includes
the following information elements: an IWU-TO-IWU
parameter, including a BSS identity and a HlO reference.
In step 7, the cordless telephone part PP delivers the
identity of the selected GSM base station BSS to the mobile
station part MS of the dual mode terminal and the mobile
station part MS sends an HlO ACCESS message according
to the specification GSM 04.08 to the selected GSM base
station BSS.

6
In step 8, when the selected GSM base station BSS
receives the HlO ACCESS message from the mobile station
part MS, it will respond with a PHYS INFO message
according to the specification GSM 04.08 to the mobile
5 station part MS in order to stop sending of access bursts
from the MS and to activate the physical channels for the
connection.
In step 9, the mobile station part of the dual mode terminal
sends an HlO COMPlEfE message according to the speci10 fication GSM 08.08 to the MSC to indicate that the mobile
station part MS of the dual mode terminal has successfully
accessed the selected GSM base station BSS. The mobile
station part MS of the dual mode terminal will inform the
cordless telephone part PP of the terminal that the handover
15 is completed and the cordless telephone part of the tenninal
can release the former DEer connection.
We claim:
1. In a mobile telecommunications system including a
fixed network comprising a plurality of mobile exchanges, a
20 plurality of first base stations connected to said mobile
exchanges and a plurality of second base stations of a
cordless telephone system, said second base stations being
connected to and under control of said mobile exchanges,
dual mode subscriber terminals each having a mobile station
25 part for radio communication with said first base stations
and a cordless telephone part for radio communication with
said second base stations, a method for performing handover
of a respective one dual mode subscriber terminal of said
dual mode subscriber terminals from one base station of said
30 second base stations to one base station of said first base
stations, comprising the steps of:
measuring the field strengths of said first base stations at
said mobile station part of said one dual mode subscriber terminal and storing measurement results,
35
detecting low quality of connection between one of said
second base stations and said cordless telephone part of
said one dual mode subscriber terminal during an
on-going call,
obtaining the stored measurement results from said
40
mobile station part by said cordless telephone part of
said one dual mode subscriber terminal,
sending a message including said obtained measurement
results and a terminal identity to said one of said second
base stations from said cordless telephone part of said
45
one dual mode subscriber terminal,
sending a handover request message from said one of said
second base stations to one of said mobile exchanges in
response to receipt of said message including said
measurement results, said handover request message
50
including said terminal identity and said measurement
results,
selecting one of said first base stations on the basis of said
measurement results,
55
sending a handover command message to said one of said
second base stations from said one of said mobile
exchanges, said message including the information of
said selected one of said first base stations,
sending a message to said cordless telephone part of said
one dual mode subscriber terminal from said one of
60
said second base stations, and said message including
information of said selected one of said first base
stations,
forwarding said information of said selected one of said
first base stations to said mobile station part via said
65
cordless telephone part of said one dual mode subscriber terminal,

WIL-0192837

5,659,598

7

8

establishing a connection between said mobile station part
a cordless telephone part for radio communication with
said second base stations,
of said dual mode terminal and said selected one of said
first base stations, and
means for measuring the field strengths of said first base
stations at said mobile station part of said dual mode
releasing said connection between said cordless telephone
subscriber terminal and storing measurement results,
part of said one dJ.Jal mode subscriber terminal and said 5
means for monitoring the quality of connection between
one of said second base stations.
one of the second base stations and said cordless
2. A method according to claim 1, further comprising the
telephone part of said dual mode subscriber terminal
steps of:
during an on-going call,
sending a handover request message to said selected one
means for requesting said stored measurement results
of said first base stations from said one of said mobile 10
from said mobile station part to said cordless telephone
exchanges to indicate that said one dual mode subpart of said dual mode terminal in response to detecting
scriber terminal is to be handed over to said selected
a lowness in quality of said connection,
base station, and
means for sending a message including said obtained
sending a handover acknowledgement message from said 15
measurement results and a terminal identity to said one
selected one of said first base stations to said one of the
of said second base stations from said cordless telemobile exchanges, said handover acknowledgement
phone part of said dual mode subscriber terminal,
message indicating a radio channel to which said one
means for receiving a message at said cordless telephone
dual mode subscriber terminal should be directed.
part of said dual mode terminal from said one of said
3. A method according to claim 1, wherein said step of 20
second base stations, said message including informaestablishing a connection comprises the steps of:
tion on the one of said first base stations which is
sending a handover access message from said mobile
selected for handover, and
station part of said one dual mode subscriber terminal
means for forwarding said information of said selected
to said selected one of said first base stations,
one of said first base stations to said mobile station part
sending an acknowledgement message to said mobile 25
from said cordless telephone part of said dual mode
station part from said selected one of said first base
subscriber terminal so as to establish a connection
stations,
between said mobile station part of said dual mode
sending a handover completed message to said selected
subscriber terminal and said selected one of said first
one of said first base stations from said mobile station
base stations.
30
part, and
5. A method according to claim 2, wherein said step of
establishing a connection comprises the steps of:
sending a handover completed message from said selected
one of said first base stations to said one of said mobile
sending a handover access message from said mobile
exchanges.
station part of said one dual mode subscriber terminal
4. In a mobile telecommunications system including a
to said selected one of said first base stations,
fixed network comprising a plurality of mobile exchanges, a 35
sending an acknowledgement message to said mobile
plurality of first base stations connected to said mobile
station part from said selected one of said first base
exchanges, and a plurality of second base stations of a
station part, and
cordless telephone system, said second base stations being
sending a handover completed message from said selected
connected to and under control of said mobile exchanges, a
one of said first base stations to said one of said mobile
40
dual mode subscriber terminal comprising:
exchanges.
a mobile station part for radio communication with said
first base stations,

* * * * *

WIL-0192838