Prior art

To identify the most relevant prior art for US patent 9253616, we will examine the patents cited during its prosecution. The "References Cited" section of the patent's Google Patents page lists these documents. While many cited patents deal with general location tracking, we will focus on those that most closely relate to the core inventive concepts of US9253616, particularly its emphasis on proximity-based content, buddy lists, and instant buddy relationships.

The independent claims of US9253616 broadly cover:

• A cellular wireless device with a GPS receiver and an application program.
• The application exchanges GPS location data with a central "Buddy Watch" server.
• The server determines and sends "content" based on the device's proximity to other mobile devices on a "buddy list" or predefined locations.
• The device displays this content and provides a user interface to manage buddy lists.
• An "instant buddy" feature allows temporary, mutual location sharing with a newly designated contact for a specified duration.

Based on these key features, the following prior art documents are highly relevant:

1. US6405047B1 - Method and system for providing location-based information to mobile users

   • Full Citation: US6405047B1, Method and system for providing location-based information to mobile users, Invented by James M. Link, Assigned to Visioglobe Inc., Published Jun 11, 2002.
   • Publication/Filing Date: Published: 2002-06-11; Filed: 2001-01-19.
   • Brief Description: This patent describes a system that provides location-based information to mobile users, comprising a location server, a content server, and a gateway server. The location server acquires location information for mobile users, and the content server delivers various types of location-based information to them via a communication network.
   • Potential Anticipation (35 U.S.C. § 102): This patent potentially anticipates elements of claims 1 and 9 of US9253616, specifically concerning a mobile device receiving "content" (location-based information) from a server, where this content is determined based on the mobile user's location (proximity to predefined locations). It establishes the concept of a system that delivers relevant information based on a device's geographical position. However, it does not explicitly detail "buddy lists" or content based on proximity to other mobile devices on such lists, nor the specific "instant buddy" functionality.

2. US6553221B1 - Communication system, client and server using location information

   • Full Citation: US6553221B1, Communication system, client and server using location information, Invented by Thomas S. Lau, Assigned to Nokia Corporation, Published Apr 22, 2003.
   • Publication/Filing Date: Published: 2003-04-22; Filed: 2001-04-20.
   • Brief Description: This patent discloses a client application on a mobile terminal and a server that together enable various location-based services. The mobile terminal utilizes its location information to activate diverse applications and to facilitate the exchange of location data with other client devices.
   • Potential Anticipation (35 U.S.C. § 102): This reference is highly relevant as it teaches a mobile terminal with a client application capable of "exchanging location information with other clients." This directly addresses a fundamental aspect of US9253616's claims 1 and 9 related to location sharing among users, which is essential for "buddy lists." While it may not explicitly name "buddy lists" or the specific mechanisms for "content based on proximity to buddies" or "instant buddies," the underlying capability of mutual location exchange between client devices is present.

3. US7050810B2 - Apparatus and method for enabling two-way communication of geographic location

   • Full Citation: US7050810B2, Apparatus and method for enabling two-way communication of geographic location, Invented by Richard D. Haney, Assigned to X One Inc., Published May 23, 2006. (Notably, the same inventor and original assignee as US9253616).
   • Publication/Filing Date: Published: 2006-05-23; Filed: 2004-01-28.
   • Brief Description: This patent describes an apparatus and method for mutual geographic location communication between two wireless devices, such as cellular telephones or PDAs, each equipped with a GPS receiver. It enables each device to transmit its location to the other, allowing both users to know the other's position.
   • Potential Anticipation (35 U.S.C. § 102): US7050810B2 is particularly relevant because it explicitly teaches "two-way communication of geographic location" between wireless devices. This directly anticipates the core mutual location sharing functionality central to all independent claims (1, 9, 17, and 24) of US9253616, and especially the underlying technology for the "instant buddy" feature. While it covers the exchange and display of location data, its abstract and claims do not explicitly detail the "central Buddy Watch server" storing various "content" beyond just location, the server determining content based on proximity to a "buddy list," explicit user interface management of "buddy lists," or the specific, temporary "instant buddy" relationship with a user-specified duration and setup protocol as detailed in US9253616. Nonetheless, it lays a strong foundation for the core location-sharing aspects.