the QoS mapping procedures. Figure 11.7 shows a handover from Mobile WiMAX to EPS. In the first step the mobile device is required to synchronize itself with the WiMAX BS and exchange basic capabilities, after which the EAP-AKA procedure is triggered for authenticating the identify presented by the MS/UE. After successful authentication, a three-way handshake is performed (with the PKMv2 protocol) between the MS/UE and BS for exchanging the security keys used over the air interface. Subsequently, the registration process begins, which triggers data path establishment between the BS and the ASN-GW, and then a service flow is set up according to the pre-provisioned subscriber profile that was downloaded from the AAA server during the authentication phase. At this point, the MS/UE assumes that the layer 2 connection is established, and its operating system triggers the DHCP procedure to obtain an IP address. In turn, this triggers a bearer establishment between the ASN-GW and the 2 In the case of handoff to EVDO, the decision is made by eNB. E2E Network Architecture and Mobility Management EPS P-GW by means of Proxy MIP (accomplished with the Proxy Binding Update and Proxy Binding Update Acknowledge messages). During this procedure, the PCRF may be contacted to retrieve policy parameters in the P-GW and ASN-GW (especially if this initial network attachment was a result of intertechnology handover). 11.6 EPS and EV-DO (HRPD) Interworking This section looks into E-UTRAN mechanisms to support active mode mobility between E-UTRAN and cdma2000 HRPD or 1xRTT. To entertain handovers between the two networks, each e-NodeB (eNB) cell is associated with a cdma2000 HRPD SectorID and/or with a cdma2000 1xRTT SectorID (generically referred to as cdma2000 reference cellid). This cdma2000 reference cellid is provided by the eNB to the MME using the cdma2000 message transfer capability over S1-AP³ (S1 Application Protocol) and forwarded to the target system via the S101 (define later) interface and corresponding interface to the cd