
Originally Posted by
CDG Reference Document #130
The PRL header information describes the properties of the whole PRL. These properties describe aspects such as its name (or identity), default behavior and the type of PRL.
The acquisition table contains acquisition records. An acquisition record provides the band and frequencies that the mobile station is to use when searching to acquire a system. Acquisition records are listed in priority order (highest priority first) in the acquisition table. The channels in the CHAN field of the records are also listed in the priority order.
The system table contains records describing a system. The system table is divided into one or more distinct segments; these are called geographical areas, or GEOs. A system record belongs to a geographical area. A geographical region would normally be used to group a set of systems found in the same physical region. Certain other aspects of a system record only have relevance within the context of a GEO, e.g. priority. A system, in the context of the system table, is identified by its SID and NID. Each system table record has an indicator, which determines within which geographic area a particular system belongs.
Other indicators declare whether the system is preferred (permitted) or negative (prohibited). Allowed systems can have relative priority with respect to each other within a geographic region, effectively making some systems more preferred than others. The priority that a system has is relative to the other systems in the same GEO. The most referred system is the most desired system and what the mobile device will always try to obtain for service. There is no limit to the number of priorities that can be present within a GEO. There can be multiple systems of equal priority. The PRL assists the mobile in the acquisition and system selection process as governed by the system determination algorithms of the particular implementation. The PRL informs the devices system determination function as to which systems are permitted, preferred and prohibited. The use of a PRL speeds up acquisition and provides the operator with flexibility in specifying mobile search behavior in both the home and roaming markets.
The operator is able to specify whether a roam condition is to be indicated on the mobiles display and, in the case where the extended roaming indicators (ERI) are supported, a richer set of indicators can be selected for display. The PRL can be stored in either NV-RAM or RUIM. An initial or default PRL would be loaded prior to distribution. A new PRL can be loaded at a customer service center using service programming tools or over the air using Over the Air Service Provisioning (OTASP). Although the PRL is defined in the OTASP specification, OTASP systems are not required in order to use PRLs. However, OTASP facilitates ease of updates once handsets are in the customers hands and as new roaming partners are added.
User Initiated PRL Download
This is the more common technique, and requires that the user take the initial action by
making a call using the activation feature code: *ACT or *228.
User dials the OTA feature code (*ACT)
User selects PRL update at voice response unit (VRU) prompt
OTA platform selects the appropriate PRL to send to the device based on factors including handset, service plan, etc.
OTA platform downloads PRL to the user over its IS-725 data connection to the MSC and then over the air using the IS-683 protocol
VRU may play music during this time
Handset resets on completion of the PRL download
Network Initiated PRL Download
This is where the network initiates an OTAPA session with the mobile device and performs the PRL download without user intervention. This requires that both the network and the device are OTAPA capable and that the OTAPA capability is not disabled.
A subscriber parameter administration security mechanism (SPASM) exists to ensure that only authorized entities can download to the device. When the device parameters are protected, the mobile device requests a 'signature' from the network and, at the same time, calculates a signature itself. The OTA system, upon receiving the devices challenge, will request the HLR to obtain an authentication signature (from the authentication center). The OTA system forwards the signature to the MS. Only when the MS reports that the two signatures match can the PRL download proceed.
Bookmarks