36 lines
2.7 KiB
Markdown
36 lines
2.7 KiB
Markdown
---
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title: "Assisted GNSS"
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chunk: 2/2
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source: "https://en.wikipedia.org/wiki/Assisted_GNSS"
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category: "reference"
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tags: "science, encyclopedia"
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date_saved: "2026-05-05T12:51:22.406310+00:00"
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instance: "kb-cron"
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---
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Control Plane Protocol
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Defined by the 3GPP for various generations of mobile phone systems. These protocols are defined for circuit switched networks. The following positioning protocols have been defined.
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RRLP – 3GPP defined RRLP (Radio Resource Location Protocol) to support positioning protocol on GSM networks.
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TIA 801 – CDMA2000 family defined this protocol for CDMA 2000 networks.
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RRC position protocol – 3GPP defined this protocol as part of the RRC standard for UMTS network.
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LPP – 3GPP defined LPP or LTE positioning protocol for LTE networks.
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User Plane Protocol
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Defined by the OMA to support positioning protocols in packet switched networks. Three generations of Secure User Plane Location (SUPL) protocol have been defined, from version 1.0 to 3.0.
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=== SUPL ===
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The SUPL (Secure User Plane Location) protocol, unlike its control-plane equivalents restricted to mobile networks, runs on the Internet's TCP/IP infrastructure. Consequently, its application extends beyond the original intended use of mobile devices and may be used by general-purpose computers. SUPL 3.0 legitimizes such use by adding admission for WLAN and broadband connections.
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Actions defined by SUPL 3.0 include a wide range of services like geofencing and billing. The A-GNSS functions are defined in the SUPL Positioning Functional Group. It includes:
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SUPL Assistance Delivery Function (SADF), which provides the basic information sent to the device in both A-GNSS modes.
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SUPL Reference Retrieval Function (SRRF), which tells the server to prepare the information mentioned above by receiving from the satellites.
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SUPL Position Calculation Function (SPCF), which lets the client or the server ask for the client's location. The server-generated location may result from MSA or from mobile cell. If a MSB (SET based) mode is used, the client reports its location to the server instead.
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The specifics of communication is defined in the ULP (Userplane Location Protocol) substandard of SUPL suite. As of December 2018, GNSS systems supported include GPS, Galileo, GLONASS, and BeiDou.
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=== PSDS ===
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The PSDS (Predicted Satellite Data Service) is a general term for vendor-specific services that provide almanac data that is effective for an extended time (e.g. 7 days), enabling offline A-GPS. Hardware manufacturers such as Qualcomm (gpsOneXTRA), Samsung, and Broadcom each run their own servers and use their own data formats. GrapheneOS runs a caching proxy for these services to help mask user identity.
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== See also ==
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Mobile phone tracking
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GNSS enhancement
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== References == |