SGSN support for QoS selection based on RAT type is introduced through this feature, this functionality improves the Operator Policy based QoS Control capabilities. Currently, the SGSN supports only PLMN based QoS selection. The Operator policy on SGSN allows the operators to control QoS for visiting subscribers (National or International roaming-in subscribers or MVNO subscribers) on an APN basis depending on the PLMN-ID or IMSI range. APN profiles are configured under the Operator Policy as either default for all APN or specific profiles for particular APN.
The following limitations are encountered when only PLMN based QoS selection is supported:
When co-locating MME and SGSN into the same node, separate Operator Policy can be configured for E-UTRAN on the MME and both GERAN/UTRAN on the SGSN but not for GERAN and UTRAN separately on the SGSN.
The Operator policy currently allows to 'allow' or 'restrict' access to the network based on zone-code (set of LA/SA for 2G/3G and TA for LTE) but does not allow restricting the QoS in specific area of the network based on zone-code.
To overcome the limitations listed above, Operator Policy based QoS Control capabilities are introduced based on RAT-Type or a combination of RAT-Type with PLMN-ID or IMSI range.