Telecommunications – Radiotelephone system – Emergency or alarm communication
Reexamination Certificate
1998-07-14
2001-11-06
Maung, Nay (Department: 2681)
Telecommunications
Radiotelephone system
Emergency or alarm communication
C455S414200, C455S456500
Reexamination Certificate
active
06314281
ABSTRACT:
TECHNICAL FIELD
This invention relates to wireless communications, and more particularly, to locating a distressed user of a wireless (mobile) unit during an emergency situation.
BACKGROUND OF THE INVENTION
The popularity of wireless telephony has grown at an exponential rate over the past several years. As an increasing number of people use wireless telephones as a substitute for traditional wireline telephones, telecommunications service providers must be ready to seamlessly provide service features and facilities normally associated with wireline service to the users of wireless telephony services.
One important and government mandated service required in both wireline and wireless telephony is public safety administration services (also known as emergency or “911” services). The hallmark of 911 service is the ability of the emergency service personnel to view the address of a distressed caller while the call is ongoing. In wireline applications, 911 service is easily administered because the caller uses equipment associated with a fixed address or location. Indeed, the caller's address aids 911 personnel in identifying appropriate emergency services units to respond to the distressed caller's request.
Wireless telephony poses an entirely new challenge for emergency service administration. Due to the very nature of wireless telephony, a distressed caller may be using a mobile unit in any geographic region where wireless service is provided. The challenge for emergency personnel and wireless service providers is to pinpoint the location of a distressed caller so that appropriate emergency service personnel may be dispatched.
Navigation systems, such as global positioning systems, have greatly enhanced the ability of emergency personnel to locate a distressed user of a mobile unit. Indeed, the current state of navigation system art allows the identification of an object within an area of one hundred (100) meters in an east-west dimension and one hundred fifty six (156) meters in a north-south dimension. Even with the impressive accuracy of existing navigation systems, there are situations in which emergency personnel have problems physically reaching a distressed user of a mobile unit. For example, if the distressed mobile unit user is in a high-rise building or a large office complex, the navigation system's resolution falls short of the desired goal of actually identifying the physical location of a distressed caller.
SUMMARY OF THE INVENTION
The need for identifying with greater accuracy the physical location (that is, within 20 meters) of a distressed caller is recognized and a technical advance is achieved in the wireless telecommunications art by the method and apparatus of the present invention. More particularly, the present invention uses a distress notification signal, in combination with a navigation system, to locate a distressed mobile unit user.
In one embodiment, an enhanced mobile unit is capable of operating in normal mode or “distress” mode. In distress mode, a distress notification signal emanates from the mobile. More particularly, a mobile switching center issues a control message to the enhanced mobile unit upon completion of a “911” or other emergency call. The control message instructs the mobile unit to operate in distress notification mode by transmitting a distress notification signal having a particular frequency and pattern. After the emergency call is completed, the mobile switching center also initiates a call to the closest (that is, nearest in geographic proximity) rescue squad mobile unit. The “closest” rescue squad and appropriate emergency personnel are determined using presently available navigation systems which identify a coarse geographic region where the distressed mobile unit user is located.
The rescue squad's mobile unit is also an enhanced mobile unit capable of receiving distress notification signals. Simultaneous with the distressed mobile unit transmitting the distress notification signal, the mobile switching center instructs the rescue squad mobile unit to tune to the frequency and pattern of the distress notification signal. Emergency service personnel in possession of the rescue squad mobile unit proceed toward the distressed mobile user by utilizing a received signal strength indicator on the rescue squad mobile unit to travel in a direction maximizing the received signal strength. In this manner, distress notification mode operation works in conjunction with the navigation system so that a precise, physical location of a mobile user is ascertained.
Advantageously, emergency services personnel are able to determine a more precise physical location of a distressed caller who is not readily identified using a navigation system alone (e.g., a caller trapped in a high-rise building or in a remote region of an office complex). In another embodiment, the distressed caller's mobile unit emanates an audible tone in addition to the distress notification signal so that emergency services personnel can hear a distress signal as the distressed mobile unit user is approached.
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Chao Jim Jingfu
Pittampalli Eshwar
Lucent Technologies - Inc.
Maung Nay
Persino Ray
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