d, optionally, a PCC (policy and charging control) infrastructure for providing dynamic policy and charging rules to the elements policing the user data traffic (typically, the ASN-GW and P-GW). Next Generation Mobile Communications Ecosystem WiMAX WiMAX MS/UE AAA/HSS ASN-GW Synchronization and capability exchange EAP authentication Security handshake Registration Data path setup Service flow setup DHCP discovery Proxy binding update PCC rule retrival Proxy binding acknowledgement DHCP offer/request/ Figure 11.7 Mobile WiMAX to EPS handover. Reproduced with permission from Taaghol et al. © 2009 IEEE [2] 11.5.1.3 Seamless Handover The 3GPP Release 8 specifications mandate that the UE makes the decision for handover between 3GPP mobile WiMAX,2 2 which features some key advantages. First, the UE can make a handover decision based on its up-to-date radio measurements, preconfigured user preferences, and all operator mobility policies downloaded from ANDSF. Second, the UE does not need to send any inter-technology radio measurement to the network. Third, the impact on the 2G/3G and mobile WiMAX access networks is minimized because, for example, there is no need for 3G radio access to receive measurement reports for WiMAX cells and make decisions in handover to WiMAX/EV-DO. In addition, there is no need for 3G radio access to keep track of the available radio resources on the WiMAX side and vice versa. Of course, this approach minimizes the coupling between 3GPP and mobile WiMAX accesses (and the associated upgrade cost) [2]. Another challenge in providing seamless handover is to maintain a consistent level of QoS between 3GPP and non-3GPP networks. WiMAX allows creation of multiple service flows, each with a specific QoS. This is very similar to the 3GPP PDP context activation procedure. In addition to this, classification rules will have to be kept common across both access networks by coordinating appropriate rules. QoS consistency between WiMAX and 3GPP accesses can be provided via the PCC which greatly simplifies 