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System Selection

System Selection. Cellular markets are divided into licensed areas Every CDMA system operates at a particular frequency or channel Every CDMA system can be uniquely identified by a combination of SID/NID/band Every CDMA system broadcasts its identifiers in overhead messages

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System Selection

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  1. System Selection • Cellular markets are divided into licensed areas • Every CDMA system operates at a particular frequency or channel • Every CDMA system can be uniquely identified by a combination of SID/NID/band • Every CDMA system broadcasts its identifiers in overhead messages • The process of a mobile device finding the “most preferred system” available in its current location in System Selection

  2. PRL • The PRL is used to determine the most preferred system available • PRL = Preferred Roaming List in the device • What it is: • In the handset • Built by the operator • Inaccessible the user • A list of systems a mobile can access • Stored in NV-RAM or R-UIM • Provisioned by OTASP systems or service programming tools • What it does: • Indicates which frequencies to search • Indicates which systems to avoid • Indicates system preferences • Speeds up acquisition • Indicates if the “roaming status” should be displayed

  3. Inside the PRL • The PRL is defined by the IS-683 standard (IS-683-A, B, C) • IS-683 defines two tables which comprise the PRL • The Acquisition Table • The System Table

  4. Acquisition Table • Comprised of Acquisition Records • Different Acquisition Records types exist for different band classes, frequencies, etc • An Indexed list of RF channels to search • Each record describes the RF environment of a particular area

  5. System Table • An Indexed list of System Records, keyed by (SID, NID) pairs • Each entry refers to a specific RF environment • System records are grouped by geographical area (GEO) • Relative Priority can be specified • Roaming display behavior can be specified • Negative (prohibited) systems can also be specified

  6. Hybrid Devices • Devices that can access both 1x and EV-DO systems • Can receive voice pages during data transfer of 1xEV-DO • Performs fairly seamless packet data session handoffs between a 1X system and a 1xEV-DO system

  7. How Hybrid System Selection works • As before, the Acquisition table is used to acquire system • EV-DO acquisition records are ignored until a 1xRTT system is acquired • System table is used to find highest priority system available in GEO • If the 1x system acquired has an association tag with an EV-DO system, then the system will search for it and try to acquire it IMPORTANT POINT: The prioritization of 1xRTT system determines whether or not EV-DO systems will be acquired depending on which ones have association tags to EV-DO system

  8. PRL Changes • New PRL format that adds support for IS-856 (1xEV-DO) systems • Includes new • Acquisition Record in Acquisition Table • System Record type in System Table for IS-856 systems • Acquisition Table • Generic Acquisition Record for IS-2000/IS-95 and for IS-856 • Specifies band class and channel number pairs • System Table • System record type is used to differentiate between IS-2000/IS-95 and IS-856 systems • In IS-856 system record type: • SID and NID related fields are replaced with Subnet-ID related fields • New Association fields to link IS-856 system to an IS2000 system

  9. New Records Acquisition Table System Table HRPD system and associated IS2000 System have different PNs HRPD System If set to 1, HRPD system is associated with an IS2000 System • Length of Subnet ID: 26 bits • AT will apply the mask to • 26 Most Significant Bits of the Sector ID. HRPD system and associated IS2000 System have different PDSNs

  10. The Subnet ID • Identifies who the EV-DO networks belongs to: Similar to SID/NID • Access Terminal uses the SubnetID field in an the PRL to determine if it should continue to stay on an acquired 1xEV-DO network • The SubnetID field is defined by a value and a length. • A length of zero • defined as a wildcard mask • Select any 1xEV-DO system • When the length is non-zero • Forms a mask on the length most significant bits of the SectorID • Sector ID received in the Sector Parameters Message • If the mask matches the length most significant bits can select this 1xEV-DO system. • If the mask does not match, the Access terminal continues to search

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