 5G radios. While this X2 connection is specified by 3GPP, LTE and 5G interworking between two 8 Deployment Aspects Different vendor LTE and 5G Same vendor LTE and 5G Thin LTE layer Open X2 5G3500 Single 5G3500 5G3500 Multi- vendor Single vendor LTE Multiband vendor LTE Multiband LTE Multiband = New 5G vendor = Incumbent LTE vendor Figure 8.27 Two options for 5G overlay from a new vendor on top of LTE network from an existing incumbent vendor. different vendors may be challenging due to the prevalence of vendor-specific imple- mentations, resulting in the need to exchange vendor-specific algorithms. If the operator would like to avoid inter-vendor X2 testing, then another option is to bring a thin layer of LTE (in the current 700, 1800, or 2100 MHz bands, for example) that can be deployed together with a new mid-band 5G carrier. This thin layer provides the anchor point for the LTE coverage network and ensures that many of the benefits of NSA architec- tures can be realized by new 5G-enabled mobile devices, without compromising the user experience of legacy LTE devices. The redirection feature can be used to move legacy LTE mobiles to the LTE multiband network, while 5G-capable mobiles are moved to the thin layer of LTE. These two multivendor options are illustrated in Figure 8.27. A traditional NSA-based solution can combine LTE and 5G data rates together in dual connectivity mode, allowing the user to leverage the full LTE+5G network capacity. This benefit can be obtained with a single vendor solution and with a multivendor solution based on an open X2 interface. If a new vendor with a thin LTE layer is introduced, LTE resources cannot be aggregated between the two vendors, and the aggregated data rate will be lower than with a single vendor. The thin layer solution may still be attractive since a large 5G carrier alone can bring very high data rates without LTE aggregation. New 5G services require a new 5G core network to fully realize the flexibility and capability of 5G including network slicing. The 5G core