Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-05-25
2002-09-10
Trost, William (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S422100, C455S440000, C342S352000, C342S351000
Reexamination Certificate
active
06449486
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to telecommunications, and more specifically to wireless messaging systems.
In connection with mobile communication systems, it is becoming increasingly important to determine the location of the communicating Mobile Unit (MU). Various systems for locating are already well known. One solution that is readily available in most modem cellular systems is to use the ID of the cell from which the MU is communicating. Typically, this information is accurate to a resolution of several miles. Another solution is to compute the location of the MU based on the cellular network signaling parameters (angle of arrival, time delay of arrival, signal strength, etc.). This information is typically accurate to several tens of meters. Yet another solution is to equip the MU with a GPS receiver which then attempts to track the location of the MU as accurately as possible. Typically, GPS receivers can compute locations to within several tens of meters of accuracy. When combined with differential corrections, the accuracy can be improved to less than 10 meters with a high degree of probability, as is known to one skilled in the art.
As far as reliability is concerned the cell ID information is the most reliable, and is guaranteed to be available as long as the cellular network is functioning normally. The network signal based location computations are less reliable, since they are dependent on several conditions being true at the time of the call. For example, most schemes require the MU to have line-of-sight visibility to multiple cellular base stations. This is not always possible. GPS based location computation is also not always reliable since the MU may be in an environment where there is no penetration of the GPS satellite signals.
SUMMARY OF THE INVENTION
The present invention provides techniques for determining the location of a mobile unit in a wireless communication system and presenting it to a remote party.
According to one aspect of the invention, the multiple location estimates available, each with possibly different resolution, reliability and latency, are presented in a consistent manner to the remote party thus enabling it to provide a consistent level of service to the user of the mobile unit.
Thus, in a scenario with first and second position estimates, the first position estimate is presented within a first predetermined time interval of call setup between said mobile unit and said remote party, and, if the second position estimate is available for presentation to the remote party, the second position estimate is presented within a second predetermined time interval after presentation of the first position estimate. If the second position estimate is not available for presentation to the remote party within the second predetermined time interval, status information on availability of the second position estimate is presented within the second predetermined time interval.
In specific embodiments, the first position estimate is derived from the identity of the cell in which the mobile unit is located, from a multitude of cell identities provided to the remote party by the mobile unit, or from the interaction of the mobile unit with the wireless network. In some embodiments the status information includes the expected time of arrival of the second position estimate. In specific embodiments, the second position estimate is derived from a GPS receiver embedded in the mobile unit. In such embodiments, the status information includes one or more of the state of the GPS receiver in the mobile unit and the availability of satellite signals to the GPS receiver in the mobile unit.
In some embodiments, if the second position estimate is available, the second position estimate is presented to the remote party after presentation of the expected time of arrival, but if the second position estimate is not available at the expected time of arrival, a second status update is presented to the remote party.
In embodiments where additional position estimates are potentially available, a similar sequencing of presentation of position estimates and status information can be implemented.
According to another aspect of the invention, the prior art cell identity based location estimate is further refined by designing a mobile unit that is capable of capturing the cell identity values from other networks in its neighborhood. The captured values are transmitted over the communication network to the remote party where all the identified cells are overlaid on a map of the locality. The final location estimate is the region of intersection of all the identified cells. This estimate is typically superior to that obtained by transmitting only one cell identity to the remote party.
A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings.
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Polaris Wireless, Inc.
Townsend and Townsend / and Crew LLP
Tran Congvan
Trost William
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