The High Rate Packet Data (HRPD) is a packet data protocol in the 3G mobile communications network based on CDMA2000. Evolved HRPD (eHRPD) is a method that allows the mobile operator to upgrade their existing HRPD packet core network using elements of the SAE/EPC architecture. Additionally, eHRPD is a more evolutionary path to LTE while also allowing for seamless service mobility — including seamless hand-offs — between the eHRPD and LTE networks.
The diagram below shows the eHRPD core network components for the interworking between E-UTRAN and eHRPD with the following reference points:
H1/H2 – The H1 reference point carries signaling information between a source HRPD Serving Gateway (S-HSGW) and a target HSGW (T-HSGW) for optimized inter-HSGW handoff.
The H2 reference point carries user traffic between a source HSGW (S-HSGW) and a target HSGW (T-HSGW) for optimized inter-HSGW handoff.
A10/A11 – The A10/A11 reference point connects the HSGW and eAN/PCF. It support for PPP-based operation (i.e., terminating the PPP signaling protocol over the main A10 connection with HDLC-like framing)
Gxa – The Gxa reference point connects the Policy and Charging Rules Function (PCRF) in the 3GPP EPC to the HSGW in the 3GPP2 eHRPD access network.
Pi* – The Pi* reference point connects the HSGW to the 3GPP2 AAA Proxy. The Pi* reference point is identical to the STa reference point. This reference point is used to authenticate and authorize the UE and carries PMIPv6 mode related Diameter parameters between the 3GPP AAA server/proxy and the 3GPP2 AAA proxy.
S101 – The S101 reference point connects the MME in the 3GPP EPS to the eAN/ePCF in the 3GPP2 eHRPD access network. This reference point provides tunneling of signaling and data between the UE and the target access network via the source/serving access network.
S103 – The S103 reference point connects the Serving Gateway (S-GW) in the 3GPP EPC to the HSGW in the 3GPP2 eHRPD network. Its function is to forward DL data between the S-GW and the HSGW to minimize packet losses in mobility from E-UTRAN to eHRPD.
S2a – The S2a reference point connects the PDN Gateway in the 3GPP EPC to the HSGW in the 3GPP2 eHRPD network. This reference point provides the user plane with related control and mobility support between eHRPD access and the P-GW.
STa – The STa reference point connects the AAA in the 3GPP EPC to the AAA in the 3GPP2 eHRPD network. This reference point is used to authenticate and authorize the UE and carries PMIPv6 mode related Diameter parameters between the 3GPP AAA server/proxy and the 3GPP2 AAA proxy.
S6b – The S6a reference point between PDN Gateway and 3GPP AAA server/proxy for mobility related authentication if needed. This reference point may also be used to retrieve and request storage of mobility parameters. This reference point may also be used to retrieve static QoS profile for a UE for non-3GPP access in case dynamic PCC is not supported.
A10/A11 — ePCF and HSGW, PPP/Open RP
S2a — HSGW and PDN GW, PMIPv6
L3-7 — Data Traffic, IPSec
User Equipment (UE)
ePCF node
PGW Node Emulation
Network Host (NH)
Security Gateway