approach is practically the only choice (e.g., if the UE is tethering, sharing, the cellular connection to other devices). 6.2.4 Open Issues and Future Work We have left several areas out of scope in this study or for partial attention. The first is the Idle Mode mobility. The second is the possible introduction of the evolved bearer to the GPRS and 3G. We stated that each Router Advertisement can contain at most one PIO. This follows the existing 3GPP specifications, but there could be justified use cases to relax the restriction. This topic is also left for further study, mainly because we currently have no robust way to differentiate between 'roles' or 'service' associated to prefixes; that is, there is no prefix coloring readily available [29]. The current design of the evolved bearer still only supports stateless address autoconfig- uration [17], which follows the existing 3GPP standards method of address configuration [15, 16]. However, investigating how to support DHCPv6 [30] and stateful address auto- configuration on the evolved bearer would admittedly be useful regarding the future developments of wireless broadband access. DHCPv6 has a number of administrative aspects that operators are keen on. Finally, we have entirely overlooked the evolved bearer when Proxy Mobile IPv6 (PMIPv6) [31] is used instead of GTP in the EPC [32]. However, we believe it is doable but definitely has additional challenges compared to GTP due a different link realization between the UE and the PGW. 6.3 LTE as the Uplink Access for Home Networks 6.3.1 Homenet at IETF IETF has worked on an interesting topic called Homenet (Home Networking), please see http://tools.ietf.org/wg/homenet/ for the latest status. The work is about introducing IPv6 in small residential home networks. The protocol work results may also find appli- cations in other small networks outside residential domains. IPv6-only home networks are possible but the coexistence of IPv4 is not ruled out. However, IPv4 specific work Deploying IPv6 in 3GPP Networks and e