Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
2000-04-04
2004-03-16
Trinh, Sonny (Department: 2685)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S076000, C455S550100, C455S075000
Reexamination Certificate
active
06708044
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of signal transmission in radio telephony and remote functional or operational control of a radio device. More specifically, the present invention relates to an apparatus and method for facilitating time-critical frequency band selection within radiotelephone-based communication apparatus operable in more than one frequency band.
BACKGROUND OF THE INVENTION
A conventional cellular network includes spaced-apart, fixed-site base stations. These base stations include transceivers for communicating with mobile stations (MS) or with hand-held phones (HHPs) which are physically present in the geographic area defined by the area covered or cell-site for each particular base station. Each HHP includes one or more transceivers for transmitting and receiving to/from the various or appropriate base stations. During conventional cellular telephone system operation, a mobile station (MS) or an HHP maintains contact with a primary base station when present within the specific geographic area or cell-site “covered” by that particular base station.
As used herein, the terms hand-held phone (HHP), mobile station (MS), and radiotelephone are used interchangeably. As is now well known in the art, traveling mobile stations traverse boundaries into “new” geographic areas (i.e., a “new” cell). Contact is maintained while traversing geographic areas by implementing communication between the MS and the “new” base station (used for maintaining communication with the land based communication system) when the HHP moves into the “new” cell or geographic area. This is often referred to as “handing-off” the phone from one base station to another. Handing-off oftentimes requires transfer to a channel comprising a different frequency within the frequency band because of the inherent construction of cellular systems.
FIG. 1
is a typical cell diagram defining a cellular configuration for a conventional cellular telephone network
100
. Cellular network
100
operates in accordance with one of a number of known air interface types, including, for example, time division multiple access (TDMA) protocol. In a TDMA system, for example, each cell within the cellular network operates with an assigned set of transmit and receive frequencies selected from one or more of the available frequency bands. Presently, each set contains multiple paired transmit and/or receive frequencies, typically referred to as channels, and which operate on different frequencies for adjacent cells. The cellular network
100
as shown in
FIG. 1
supports operation in both the cellular (approximately 800-900 MHz) band and personal communication service (PCS) band (approximately 1.9-2.0 GHz).
Cellular network
100
includes a base station (BS)
14
(
1
)-(
15
) within each cell
12
(
1
)-(
15
). The base stations
14
engage in simultaneous communications with a plurality of mobile stations (MS's, radiotelephones, HHP's, carphones, handsets, etc.)
16
operating roughly within the area of coverage associated with a particular cell
12
. At least one control channel is assigned to each base station
14
and is used to carry system radio frequency (RF) control signals between the base stations
14
and the HHPs
16
operating within the base station's area of coverage. These control channels also assist the network with mobile station cell re-selection. Mobile switching centers (MSC)
18
are connected with each other and connected with the public switched telephone network (PSTN)
20
, and communicate using control signals and voice/data signals to selectively connect subscriber voice and data communications to the mobile stations
16
through the base stations
14
. MSC's are also used in handing-off subscriber communications from a traffic channel of one cell
12
to a traffic channel of another cell as the mobile station
16
roams throughout the cellular service areas (i.e., the network).
For example and referring to
FIG. 1
, MS
16
(
1
) may be a cellular only device which is traveling through areas covered by base stations
14
(
2
),
14
(
7
),
14
(
12
), and
14
(
15
) on a path from A-to-a. MS
16
(
1
) will communicate with cellular band base station
14
(
2
) while in its area of coverage
12
(
2
). MS
16
(
1
) will be handed off to cellular/PSC band base station
14
(
7
) which will communicate with MS
16
(
1
) in the cellular band since MS
16
(
1
) does not have the capability to communicate on the PCS band. In a similar manner, MS
16
(
1
) will be handed off to cellular band base stations
14
(
12
) and
14
(
15
) when the MS is in their areas of coverage.
MS
16
(
2
) may, for example, be a PCS only device which is traveling through areas covered by base stations
14
(
1
),
14
(
5
), and
14
(
10
), and not communicate with BS
14
(
14
) while on a path from B-to-b. MS
16
(
2
) will communicate with cellular/PCS band base station
14
(
1
) while in its area of coverage
12
(
1
) using the PCS band only. When MS
16
(
2
) moves into the area of coverage
12
(
5
) of base station
14
(
5
), then the MS will be handed off to BS
12
(
5
). In a similar manner, MS
16
(
2
) will be handed off to cellular/PCS band base stations
14
(
10
). However, when MS
16
(
2
) reaches the area of coverage
12
(
14
) of base station
14
(
14
), cellular only base station
14
(
14
) will not be able to provide service, and MS
16
(
2
) will attempt to find service by roaming. When no PCS capable base station is available, this MS
16
(
2
) will typically report “No Service”.
Where, for example, MS
16
(
3
) is a dual band device, (e.g., cellular and PCS), then in a similar manner as MS
16
(
1
) and MS
16
(
2
), as MS
16
(
3
) travels on a path from C-to-c, the phone may operate in the cellular band while in the area of coverage
12
(
13
) of base station
14
(
13
), and in either the cellular band or the PCS band when it is in the areas of coverage
12
(
10
),
12
(
7
), and
12
(
4
). In a similar manner, where MS
16
(
4
) is also a dual band device, it may operate in cellular band while in the area of coverage
12
(
3
) of base station
14
(
3
) and may operate in PCS band while in the areas of coverage
12
(
5
) and
12
(
7
) of base stations
14
(
5
) and
14
(
7
). However, as MS
16
(
4
) leaves the area of coverage
12
(
7
), it will have to operate in the cellular band to maintain communications with base station
14
(
9
). Dual MS
16
(
5
), however, would not be required to switch between the cellular band and the PCS band while traveling on a path from E-to-e. In the PCS (only) band mode, MS
16
(
5
) can communicate with base stations
14
(
1
),
14
(
5
),
14
(
7
) and
14
(
4
), while traveling from E-to-e. In the cellular (only) band mode, MS
16
(
5
) can communicate with base stations
14
(
1
) or
14
(
3
),
14
(
5
) or
14
(
1
),
14
(
2
) or
14
(
5
),
14
(
2
) or
14
(
7
),
14
(
7
) or
14
(
4
), and perhaps
14
(
9
) while traveling from E-to-e.
Where MS
16
(
1
),
16
(
3
),
16
(
4
), and
16
(
5
) are present simultaneously in an area of coverage
12
(
7
) such as that controlled by base station
14
(
7
), then it is advantageous to operate certain MS devices in one band while operating other of the MS devices in the other band.
Traditionally, mobile radiotelephones were constructed to operate in either the cellular band or the more recently allocated PCS band networks. For example, hand-held phones were constructed exclusively for a wireline
on-wireline network (cellular band) or PCS network (PCS band).
FIG. 2
a
shows a block diagram of a conventional radio communication (hand held phone) device
200
including a transceiver (FIG. 3 of U.S. Pat. No. 5,430,416, issued Jul. 4, 1995, to Black, and the patent incorporated herein by reference). Device
200
provides the ability for a mobile station (or HHP) to communicate with a base station. In such a device or HHP, communication is carried out, for example, over various radio frequency (RF) channels. Upon receipt of an RF signal transmitted by an HHP present in a
Patel Mukesh
Puknat William
Zhang Dongan
NEC America Inc.
Scully Scott Murphy & Presser
Trinh Sonny
LandOfFree
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