11 Compatibility Issues

23.0603GPPGeneral Packet Radio Service (GPRS)Release 17Service descriptionStage 2TS

Non-GPRS MSs in A/Gb mode PLMNs that support GPRS shall, without changes, be able to continue operation.

PLMNs that do not support GPRS shall, without changes, be able to continue interworking with PLMNs that do support GPRS.

An A/Gb mode MS shall be able to access GPRS services with GPRS-aware SIMs, and with SIMs that are not GPRS-aware. A GPRS-aware SIM is able to store information in the elementary files EFKcGPRS and EFLOCIGPRS, as defined in TS 51.011 [28].

The compatibility of SIMs and USIMs with A/Gb mode MSs or Iu mode MSs is defined in TS 31.102 [36].

11.1 Interaction between Releases 97/98 and 99

NOTE: Unless specifically indicated, references to release 97 in this clause refer to both release 97 and release 98.

11.1.1 Interactions Between GTP v0 (R97) and GTP v1 (R99)

Support for GTPv0 is removed from 3GPP Rel-8 GTPv1 specification. Therefore, the interactions between GTPv0 (R99) and GTPv1(R99) is not defined and supported, for protocol details see "Removing support for GTPv1 to GTPv0" in TS 29.060 [26].

11.1.2 Interactions Between MS R97 and CN R99

When an R97 MS activates a PDP context and both the SGSN and the GGSN support R99, the QoS profile shall not be converted to R99.

11.1.3 Interactions Between SM R97 and SM R99

The SM protocol shall be backwards compatible.

11.1.4 Interactions Between MAP R97 and MAP R99

The MAP protocol shall be backwards compatible to allow interworking between HLRs and SGSNs that support different releases.

11.1a Interactions between Release 7 and earlier Releases

11.1a.1 Interactions Between CN (R7) and Iu-mode RAN (pre-R7)

A Gn/Gp SGSN supporting R7 or later shall be configured with knowledge of the Release supported by the Iu-mode RAN. In addition to the QoS profile negotiation mechanism defined in clause "Activation Procedures", the Gn/Gp SGSN shall further select specific values of the QoS profile to be compliant with the Release supported by the Iu-mode RAN, as specified in TS 23.107 [58] for that Release, before contacting the GGSN/P-GW, if appropriate, and performing RAB assignment procedures.

11.1a.2 Interactions between CN and RAN to handle Rel‑7 QoS extensions

To avoid that bit rates exceeding 16 Mbps are assigned to UEs potentially not capable of handling NAS QoS extensions introduced in Rel‑7, the RNC indicates a "Higher bitrates than 16 Mbps flag" in the RANAP Initial UE Message, RANAP Relocation Complete, or RANAP Enhanced Relocation Complete as defined in TS 25.413 [56b] to the SGSN. This flag is set depending on the "Access stratum release indicator" defined in TS 25.331 [52]. The "Higher bitrates than 16 Mbps flag" is set to "allowed" if the "Access stratum release indicator" is set to a release of Rel‑7 or higher. Otherwise, it shall be set to "not allowed".

If the SGSN receives the "Higher bitrates than 16 Mbps flag" in RANAP Initial UE Message, RANAP Relocation Complete, or RANAP Enhanced Relocation Complete, it stores it as received in the MM Context of the UE, unless, based on implementation specific logic, the SGSN derives from other information that the UE either supports bitrates higher than 16 MBit/s or not. If "Higher bitrates than 16 Mbps flag" is not included by RANAP (since the employed version of the RANAP protocol does not support this feature), the SGSN sets the corresponding flag in the MM Context of the UE depending on implementation.

NOTE: If the employed RANAP version does not provide the information the SGSN can infer information that the UE is capable of handling NAS QoS extensions introduced in Rel‑7 from MS network capability information, e.g. from information that the UE supports LTE/EPC.

If the "Higher bitrates than 16 Mbps flag" in the MM Context of the UE is set to "not allowed" and if the authorized APN-AMBR is higher than 16 Mbps, the S4-SGSN shall, for non-GBR bearers, restrict the MBR sent to the UE to within 16 Mbps. For GBR bearers, the request shall be rejected if the authorized GBR/MBR is higher than 16 Mbps in the activation and modification procedures.

11.2 Network Configuration for Interaction with E-UTRAN and S4-SGSNs

GPRS idle mode mobility procedures performed by Gn/Gp SGSNs specify a set of sequence number handling functions, e.g. the exchange of sequence numbers during Routing Area Update procedure. E-UTRAN based and S4-SGSN based idle mode mobility procedures don’t specify any such sequence number mappings for mobility scenarios. To avoid interoperation issues a network that deploys E-UTRAN and/or S4-SGSNs shall not configure usage of the feature "delivery order required" for PDP contexts of PDP type IPv4, IPv6, IPv4v6 or Non-IP. Also the network shall not configure usage of lossless PDCP of UTRAN and the GERAN SGSN shall not configure usage of acknowledged mode LLC/NSAPI/SNDCP.

11.3 Interactions between CN and RAN to support higher bit rates

A Gn/Gp SGSN or S4-SGSN supporting QoS extensions available from this release of specification shall be configured with knowledge of the Maximum Bit Rate and Guaranteed Bit Rate supported by the Iu-mode RAN. In addition to the QoS profile negotiation mechanism defined in clause 9.2.2 "Activation Procedures", the Gn/Gp SGSN or S4-SGSN shall further select specific values of the QoS profile to be compliant with the Maximum Bit Rate supported by the Iu-mode RAN, as specified in TS 23.107 [58] for that release, before performing RAB assignment procedures.

For GBR bearers, the Gn/Gp SGSN shall restrict the Guaranteed Bit Rate in the same way as described for the Maximum Bit Rate above. For GBR bearers, the S4-SGSN shall reject an EPS Bearer Activation or Modification including a Guarantee Bit Rate that is not supported by the Iu-mode RAN. RAB Assignment procedures shall not be initiated in this case.