Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-08-16
2002-04-23
Hunter, Daniel (Department: 2689)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S427000, C455S430000, C320S118000, C320S118000, C320S118000
Reexamination Certificate
active
06377801
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of communications in general, and more particularly, to call configuration in satellite radiotelephone systems.
BACKGROUND OF THE INVENTION
Satellite radiotelephone communications systems are widely used to provide radiotelephone communications among satellite radiotelephones and with cellular and conventional wired telephones. For example, the satellite radiotelephone system
101
shown in
FIG. 1
may allow a first satellite radiotelephone
100
to communicate with a second satellite radiotelephone
105
via a satellite
110
. The first and second satellite radiotelephones
100
,
105
can conduct a call by transmitting signals from the transmitting satellite radiotelephone to the satellite
110
that relays the signals to a switching center
115
which relays the signals to the receiving satellite radiotelephone via the satellite
110
over first, second, and third channels
120
a-c
(i.e., a dual hop call). Unfortunately, the dual hop call configuration described above may introduce long delays in signal transmission due to the distance between the first and second satellite radiotelephones
100
,
105
and the satellite
110
.
Therefore calls in satellite radiotelephone systems
101
between the first and second satellite radiotelephones
100
,
105
may be routinely conducted as single hop calls. In particular, the switching center
115
may determine that the first and second satellite radiotelephones
100
,
105
are both satellite radiotelephones served via the satellite
110
. The call from the first satellite radiotelephone
100
to the second satellite radiotelephone
105
may then be conducted over a transmission path
125
via the satellite
110
(i.e., a single hop). In other words, the single hop configuration may reduce delays in signal transmission by eliminating transmissions between the switching center
115
and the satellite
110
once the call is in an active state. For example, once the second satellite radiotelephone
105
accepts the call, the signals transmitted between the first and second satellite radiotelephones are not routed through the switching center
115
.
Unfortunately, the configuration of such single hop calls may introduce some disadvantages. For example, it may be difficult to encode voice data transmitted between the first and second satellite radiotelephones
100
,
105
in a single hop configuration. Such encoding is typically performed by systems accessible to the switching center
115
rather than the satellite
110
. Consequently, the elimination of signaling between the satellite
110
and the switching center
115
in the single hop call may reduce the accessibility of the encoding systems. In addition, call services, such as call conferencing between three or more parties, is typically performed by systems accessible to the switching center
115
. Accordingly, a single hop call configuration may also reduce the availability of those services to the first and second satellite radiotelephones
100
,
105
involved in the single hop call.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide satellite radiotelephones, systems and methods of operating satellite radiotelephone systems which may provide improved performance in how calls are conducted in satellite radiotelephone systems.
These, and other objects of the present invention, may be provided by methods, user terminals, and systems that conduct calls from a satellite user terminal to a user terminal via a satellite in a satellite radiotelephone system by transmitting information from the satellite user terminal to the satellite radiotelephone system via the satellite. The information includes a request to conduct an active state of the call from the satellite user terminal to the user terminal via a ground segment in the satellite radiotelephone system. The active state of the call is conducted from the satellite user terminal to the user terminal via the ground segment based on the request. In other words, single hop routing of a dual-hop call may be selectively bypassed at the request of a mobile terminal.
In one embodiment of the present invention, the call is conducted as a single or dual hop call under the control of the satellite radiotelephone that initiates the call. In particular, a first satellite radiotelephone calling a second satellite radiotelephone can instruct satellite radiotelephone system to conduct the call as a dual hop call by transmitting a suspension code to a switching center, thereby possibly avoiding a default action by the switching center to configure the call as a single hop. Consequently, data transmitted between the first and second satellite user terminals may be processed by systems available to the ground segment. For example, audio data may be encoded or other users may join the call between the first and second satellite radiotelephones using a teleconference function available to the ground segment.
In a further aspect of the present invention, a determination is made whether the user terminal being called is a second satellite user terminal that communicates with the satellite radiotelephone system via the satellite. The active state of the call is conducted between the satellite user terminal and the user terminal via the ground segment in response to the request if the user terminal is a second satellite user terminal that communicates with the satellite radiotelephone system via the satellite.
In another aspect of the present invention, the information includes a suspension code or suspension message which requests the suspension of single hop call configuration for the active state of the call. The suspension code can comprise a suffix or prefix associated with a telephone number that identifies the second satellite user terminal in the satellite radiotelephone system.
REFERENCES:
patent: 5596330 (1997-01-01), Yokev et al.
patent: 5956646 (1999-09-01), Kolev et al.
patent: 6081709 (2000-06-01), Karabinis
patent: 6108318 (2000-08-01), Kolev et al.
patent: 6198921 (2001-03-01), Youssefzadeh et al.
patent: 6230026 (2001-05-01), Schwaller et al.
patent: 6278876 (2001-08-01), Joshi et al.
patent: WO 98/25239 (1998-06-01), None
patent: WO 98/39857 (1998-09-01), None
Asokan Ramanathan
Kolev Javor
Ericsson Inc.
Hunter Daniel
Myers Bigel & Sibley & Sajovec
Tran Pablo N
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