Emergency Call Handling - Cisco ASR 5000 Series 3G Home NodeB Administration Manual

HNB Gateway in Wireless Network
impact the system's ability to service subscriber sessions. Congestion control helps identify such conditions and invokes
policies for addressing the situation.
Congestion control operation is based on configuring the following:
 Congestion Condition Thresholds: Thresholds dictate the conditions for which congestion control is enabled
and establishes limits for defining the state of the system (congested or clear). These thresholds function in a
way similar to operation thresholds that are configured for the system as described in the Thresholding
Configuration Guide. The primary difference is that when congestion thresholds are reached, a service
congestion policy and an SNMP trap, starCongestion, are generated.
A threshold tolerance dictates the percentage under the configured threshold that must be reached in order for
the condition to be cleared. An SNMP trap, starCongestionClear, is then triggered.
 Port Utilization Thresholds: If you set a port utilization threshold, when the average utilization of all
 Port-specific Thresholds: If you set port-specific thresholds, when any individual port-specific
 Service Congestion Policies: Congestion policies are configurable for each service. These policies dictate how
services respond when the system detects that a congestion condition threshold has been crossed.
Important:
Administration Guide.

Emergency Call Handling

The HNB-GW supports the handling of Emergency call in accordance with the following standards:
 3GPP TS 25.467 V9.3.0 (2010-06): 3rd Generation Partnership Project; Technical Specification Group Radio
Access Network; UTRAN architecture for 3G Home Node B (HNB); Stage 2 (Release 9)
 3GPP TS 33.102 V9.1.0 (2009-12): 3rd Generation Partnership Project; Technical Specification Group Services
and System Aspects; 3G Security; Security architecture Release 9)
The HNB-GW provides access for all UE/HNB when emergency call initiated. In case of non CSG UEs or non CSG
HNBs, after Emergency call is finished, the context established between the HNB and operator's core network entities
for UEs who can not get access over the HNB is released to prevent the UE from accessing non-emergency services.
HNB-GW handles the emergency call in following way:
 Authentication: In case of emergency call, HNB sends a UE REGISTRATION REQUEST message with
"Registration cause" as emergency call and excludes the "UE Permanent identity" (i.e IMSI) and HNBGW
does not perform access control for emergency call case.
 Single Iu and Single RAB: In case of emergency call, HNBGW does not allow multiple RABs for UE. This
means that UE must have only one Iu connection, either CS or PS, and have only one RAB on that Iu
connection. HNB-GW implements "Single IU, Single RAB policy" when UE registration comes with
Emergency.
The RUA-CONNECT has an IE called "establishment cause" which can take values as "Normal" or
"Emergency". If UE-registration was due to emergency then RUA-CONNECT must contain "Emergency". If
RUA-CONNECT contains "normal" then HNB-GW rejects it.
While rejecting RUA connection or RAB connection the HNB-GW uses following reject cause:
 RUA - Misc: unspecified
OL-25069-03
ports in the system reaches the specified threshold, congestion control is enabled.
threshold is reached, congestion control is enabled system-wide.
For more information on Congestion Control support, refer Congestion Control chapter in System
Cisco ASR 5000 Series 3G Home NodeB Gateway Administration Guide ▄
Features and Functionality - Base Software ▀
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