ASN Paging Controller and Location Registry Overview

ASN Paging Controller and Location Registry Overview
 
 
The ASN Paging Controller and Location Registry (PC/LR) provides the paging and location update to WiMAX subscriber in IEEE 802.16 Mobile WiMAX radio access networks. This service can be used as a standalone product or in combination with ASN Gateway as co-located services on same chassis.
 
Introduction
ASN Paging Controller and Location Registry (PC/LR) supports connection management and mobility across cell sites and inter-service provider network boundaries by processing subscriber control and bearer data traffic.
Each ASN Gateway can concentrate traffic from many radio base stations. This reduces the required number of devices under management and minimizes connection set-up latency by decreasing the number of call hand-offs in the network.
Paging and Idle Mode Operation maintains a track and alert for MSs when they are in idle mode to save battery power. Paging is executed to alert MSs when there is an incoming message. Figure 8 illustrates the paging operation and paging and idle mode elements in the WiMAX network system.
 
ASN Paging Controller and Location Registry in WiMAX Networks
In WiMAX networks, a mobile station is tracked when it is in idle mode. The information is stored to a location register (LR). The tracking area is larger than the cell size because a paging group (PG) comprises multiple cells. When a mobile station moves across paging groups, its location is updated via R6 and/or R4. The paging controller (PG) in ASN-GW retrieves the location from the LR and alerts the paging agent in (PA) in the base station to signal to the mobile station.
Location information for idle mode subscribers is maintained in a location register central database that is co-located on an anchor paging controller. Idle mode can be initiated by the mobile device or the network. The paging controller retains subscriber session context information in addition to supervising paging activities. It also represents an authentication liaison between the user device and the AAA server. As the subscriber roams across cell sites, it is associated with a group of base stations known as a paging group. Location updates to the LR database are conveyed over R6 and R4 messages between the relay paging controller serving ASN and the A-PC/LR. When a remote host attempts to reach an idle mode subscriber device, the anchor paging controller alerts the paging group members when it receives downlink traffic by requesting the paging agent in the base station to signal the idle mode subscriber.
 
Description of PC/LR Support
The PC/LR runs as a stand-alone function in a separate chassis or as an integrated service on same chassis as the Anchor Authenticator (A-PC)/Anchor Datapath (A-DP) ASN Gateway. The idle mode LR database uses distributed software architecture and provides an LR manager task that partitions smaller database volumes across separately running session manager tasks in the system. The implementation is based on a topologically unaware paging scheme in which the A-PC does not have global awareness of all member base stations in a paging group. The A-PC uses a single-step paging operation where paging notifications are sent to the last-reported serving paging controller or directly attached base station.
Idle mode operation is very important in order for any cellular system to keep the mobile device reachable when it is inactive. It enables mobility in addition to conserving battery life. Idle mode paging also eliminates the requirements of independent VLRs/HLRs, when it is supported as an integrated function in the ASN Gateway system.
 
Licenses
The ASN PC/LR service is a separate product from the ASN Gateway. You must purchase the WiMAX Paging Controller/Location Register product license separately to enable this service.
 
Paging and Location Update Procedures
This section provides an overview of the ASN Gateway’s paging and location update procedures.
The system provides following components for the paging controller, paging group and location registry functionality.
 
Paging Controller (PC)
The paging controller is a functional entity that administers the activity of idle mode mobile stations in the network. It is identified by PC ID, which maps to the address of a functional entity in a WiMAX network. In this implementation, the PC is co-located with ASN Gateway. There are two types of PCs:
 
Anchor PC: For each idle mode MS, there is a single anchor PC that contains the updated location information of the MS.
Relay PC: There are one or more other PCs in the network, called relay PCs, that participate in relaying paging and location management messages between the paging agent and the anchor PC.
 
Paging Agent (PA)
The paging agent is a functional entity, implemented in an ASN base station, that handles the interaction between PC- and paging-related functionality.
 
Paging Group (PG)
A paging group is a logical entity comprising one or more paging agents. A paging group resides entirely within a NAP boundary. Paging groups are managed by the network management system and provisioned per the access network operator’s provisioning requirements.
 
Location Register (LR)
A location register is a distributed database, with each instance corresponding to an anchor PC. Location registers contain information about idle mode MSs. The information for each MS includes:
 
An instance of a location register is associated with every anchor PC.
Paging Controller and Location Update functionality supports following operation and procedures in ASN Gateway:
Location Update Procedure
Location Update with Paging Controller Relocation
Paging Operation
MS Initiated Idle Mode Entry
MS Initiated Idle Mode Exit
 
Location Update Procedure
This section describes the secure location update procedure for a WiMAX MS.
The following figure and table provides a high-level view of the steps involved in a secure location update.
Location Update Flow
Location Update Procedure Flow Description
 
Location Update with Paging Controller Relocation
This section describes the secure location update with PC relocation procedure for a WiMAX MS.
The following figure and table provides a high-level view of the steps involved in a secure location update with PC relocation.
Location Update with PC Relocation - Procedure Flow
 
Paging Operation
This section describes the paging operation for a WiMAX MS.
The following figure and table provides a high-level view of the steps involved in the paging operation call flow of an MS.
 
Paging Operation Procedure Flow
Paging Operation Procedure Flow Description
If paging action is authorized, Anchor PC retrieves the MS paging information and constructs Paging_Announce message. The Anchor PC issues one or more Paging_Announce messages based on its knowledge of the Paging Region topology as shown in sections XXXXX.The Anchor PC starts a timer TR4_Paging_Announce when it sends out the first Paging_Announce message and waits for the paging response. The Anchor PC sets a paging re-transmission counter N. If the Anchor PC does not receive a paging response, it retransmits the Paging_Announce message prior to the expiration of the timer TR4_Paging_Announce.If the Anchor PC is topologically aware of the defined Paging Group (PG), including the last BS from which the MS performed location update, the Anchor PC directly issues Paging_Announce messages to all or some subset of the Paging Group members. The members consist of BSs and/or relay PCs in the region.If the Anchor PC is topologically unaware of the Paging region or the BSs defined in the Paging group, the Paging_Announce messages are sent to the known Relay PC(s). The Relay PC(s) forwards the announce message to one or more BSs in the Paging region.
 
MS Initiated Idle Mode Entry
This section describes the MS-initiated idle mode entry procedure for a WiMAX subscriber.
The following figure and table provides a high-level view of the steps involved in MS-initiated idle mode entry call flow of an SS/MS.
MS Initiated Idle Mode Entry Procedure Flow
MS Initiated Idle Mode Entry Procedure Flow Description
 
MS Initiated Idle Mode Exit
This section describes the MS-initiated idle mode exit procedure for a WiMAX subscriber.
The following figure and table provides a high-level view of the steps involved in MS- initiated idle mode exit call flow of an SS/MS.
 
MS Initiated Idle Mode Exit Procedure Flow
MS Initiated Idle Mode Exit Procedure Flow Description
 
Supported Platforms and Software
ASN PC-LR is available for all chassis running StarOS Release 8.0 or later.
 
 

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