Telecommunications – Radiotelephone system – Out-of-range indication
Reexamination Certificate
1998-06-15
2002-11-19
Bost, Dwayne (Department: 2681)
Telecommunications
Radiotelephone system
Out-of-range indication
C455S418000, C455S575100, C455S426100
Reexamination Certificate
active
06484027
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to the field of communications and the use of wireless handsets. More particularly, the present invention relates to wireless handsets with enhanced functionality, including the ability to operate within a wireless network and in a direct handset-to-handset communication mode.
2. Acronyms
The written description provided herein contains acronyms which refer to, for example, various communication services, components and techniques, as well as features relating to the present invention. Although some of these acronyms are known, use of these acronyms is not strictly standardized in the art. For purposes of the written description herein, acronyms will be defined as follows:
Citizens Band (CB)
Complimentary Metal Oxide Semiconductor (CMOS)
Customer Premise Equipment (CPE)
Electronically Erasable Programmable Read Only Memory (EEPROM)
Federal Communications Commission (FCC)
Group System for Mobile Communications (GSM)
Interim Standard (IS)
Liquid Crystal Display (LCD)
Mobile Identification Number (MIN)
Mobile Switching Center (MSC)
Mobile Telephone Switching Office (MTSO)
Number Assignment Module (NAM)
Personal Access Communication System (PACS)
Personal Communications Network (PCN)
Personal Communications Services (PCS)
Personal Handyphone Systems (PHS)
Public Land Mobile Network (PLMN)
Plain Old Telephone Service (POTS)
Public Switched Telephone Network (PSTN)
Random Access Memory (RAM)
System Access List (SAL)
Supervisory Audio Tone (SAT)
System Identification Code (SID)
Subscriber Identity Module (SIM)
System Operator Code (SOC)
Signal Strength (SS)
Transmission Control Protocol/Internet Protocol (TCP/IP)
Time Division Multiple Access (TDMA)
3. Background and Material Information
Traditionally, wireless handsets have been provided to facilitate mobile communications. Such handsets are typically assigned a unique wireless or mobile identification number. By dialing the number assigned to the handset, a user may attempt to access a wireless handset user through the wireless network infrastructure. The wireless network may facilitate communications between two mobile wireless handset users, or between a user located at a fixed location (such as, for example, a Plain Old Telephone Service (POTS) station location) and a wireless handset user. In addition, the wireless network may comprise a cellular network or a mobile telephone network to facilitate communication.
Wireless networks enable mobile station users to roam over large geographic areas while maintaining immediate access to communication services. Mobile station users often carry their handsets or have them installed in their vehicle(s). Mobile stations comprising cellular telephones or wireless handsets may be operable in cooperation with cellular or Personal Communications Services (PCS) communications systems. Cellular communication systems typically provide service to a geographic area by dividing the area into many smaller areas or cells. Each cell is serviced by a radio transceiver (i.e., a transmitter-receiver base station or cell site). The cell sites or base stations may be connected to Mobile Telephone Switching Offices (MTSOs) or Mobile Switching Centers (MSCs) through landlines and/or other communication links. The MSCs may, in turn, be connected via landlines to the Public Switched Telephone Network (PSTN).
FIG. 1
illustrates the main components of a conventional cellular network. As shown in
FIG. 1
, a wireless handset
38
may place or receive calls by communicating with a cell site
30
or a cell site
40
, depending upon the location of the wireless handset and the cell coverage area that is provided by each cell site (i.e., cell coverage area
35
of cell site
30
or cell coverage area
45
of cell site
40
). For purposes of illustration, wireless handset
38
is depicted in
FIG. 1
as being able to communicate with either cell site
30
or cell site
40
, even though the wireless handset is not illustrated as being located within cell coverage area
35
or cell coverage area
45
. Under normal operating conditions, the extent to which wireless handset
38
will be able to communicate with cell site
30
or cell site
40
will depend on the geographic location of the wireless handset and the size of the cell coverage area of each cell site. Further, although only two cell sites are depicted in
FIG. 1
, the entire cellular network may include, for example, more than two cell sites. In addition, more than one cell site may be connected to each MSC and more than one wireless handset
38
may be operating within each cell site.
Wireless handset
38
may include a conventional cellular telephone unit with a transceiver and antenna (not shown) to communicate by, for example, radio waves with cell sites
30
and
40
. Various air-interface technologies may be implemented to facilitate communication between each wireless handset and the cell sites. Cell sites
30
and
40
may both include a radio transceiver (not shown) and be connected by landlines
16
or other communication links to MSCs
24
,
28
. A PSTN
12
is also connected to each of the MSCs
24
,
28
by landline
16
or other communication links. PSTN
12
may also be connected to fixed Customer Premise Equipment (CPE)
6
(which may include telephone equipment) by communication or trunked lines
10
.
The MSCs
24
,
28
may be conventional digital telephone exchanges that control the switching between PSTN
12
and the cell sites
30
and
40
to provide wireline-to-mobile, mobile-to-wireline and mobile-to-mobile call connectivity. Each MSC may perform various functions, including: (i) processing mobile station status data received from the cell site controllers; (ii) handling and switching calls between cells; (iii) processing diagnostic information; and (iv) compiling billing information. The transceiver (not shown) of each cell site
30
and
40
provides communications, such as voice and data, with each wireless handset
38
while it is present in its geographic domain. The MSCs
24
,
28
may track and switch wireless handset
38
from cell site to cell site, as the wireless handset passes through various coverage areas. When wireless handset
38
passes from one cell to another cell, the MSC of the corresponding cell may perform a “hand-off” that allows the wireless handset to be continuously serviced.
In the current North American cellular system, any given area may be serviced by up to two competing service providers of cellular airtime communication services. By Federal Communications Commission (FCC) regulations, the two competing cellular service providers are assigned different groups of frequencies within the 800-900 MHZ region through which services are provided. A frequency set typically includes control channels and voice channels. The control channels are used for preliminary communications between a mobile station and a cell site for setting up a call, after which a voice channel is assigned for the mobile station's use on that call. The assigned frequency sets are generally referred to as “A band frequencies” and “B band frequencies”. Typically, the A band frequencies are reserved for non-wireline service providers, while the B band frequencies are reserved for wireline service providers. While each frequency set for a given cellular service area is assigned to only one service provider, in different service areas the same frequency set may be assigned to different service providers or companies. Cellular service providers often charge usage fees for airtime since they have to purchase or license the wireless bandwidth over which cellular calls take place, and because they have to maintain their wireless network. The FCC, however, has also designated unlicensed bands in Northern America which do not require a license to operate on if the transmit power is sufficiently low. For example, the 902-928 MHZ Industrial, Scientific and Medical band is unlicensed in the United States. This band is commonly used for home cordless teleph
Green Charles A.
Harbin Steven A.
Mauney Daniel W.
Sullivan Marc A.
Bost Dwayne
Craver Charles
Greenblum & Bernstein P.L.C.
SBC Technology Resources Inc.
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