itecture can be found in [2]. 5.7 EV-DO Revisions Comparison EV-DO Rev. A/B enables advance, bandwidth hungry, elastic and non-elastic applications to enhance operators' profits. Table 5.2 provides a summary of the technical and performance attributes of the different EV-DO revisions. The data rates and data throughputs are provided on a single 1.25 MHz carrier in Table 5.2. CDMA2000 Evolution and Migration to 3GPP LTE The abandonment of UMB by the major EV-DO operators in 2007/2008 has caused fury in vendors' and lower tier operators' communities. Till now the entire EV-DO industry is looking to find ways to save the billions of dollars they have invested. The answer SO far has been LTE. A number of challenges need to be addressed to complete EV-DO migration to 3GPP-based LTE. First is the availability and allocation of frequencies for LTE. Figure 5.11 shows a possible transi- tion scheme from EV-DO to LTE in a 5 MHz spectrum. EV-DO operators can start from single LTE 1.4 MHz carrier and eventually migrate to full LTE. Secondly, proper handoff boundaries and the inter-working issues at the radio, core and IP levels need to be identified and resolved. Thirdly, seam- less continuity of applications and QoS across two networks will be required. Lastly and importantly, Next Generation Mobile Communications Ecosystem 5 MHz Band 3 EVDO Carriers 625 kHz 625 kHz EVDO 1.25 MHz Carrier EVDO 1.25 MHz Carrier EVDO 1.25 MHz Carrier Guard Band Guard Band 2 EVDO Carriers & 625 kHz LTE 1.4 MHz Carrier EVDO 1.25 MHz Carrier EVDO 1.25 MHz Carrier 1 LTE Carrier Guard Guard Band 1 EVDO Carrier & 625 kHz LTE 1.4 MHz Carrier LTE 1.4 MHz Carrier EVDO 1.25 MHz Carrier 2 LTE Carriers Guard Guard Band 5 MHz LTE Carrier LTE 5 MHz Carrier Figure 5.11 EV-DO migration to LTE multi-mode devices that can support both EV-DO and LTE at multiple frequency bands will be essential. LTE migration will start in data hotspots and as capabilities of LTE grow and start to achieve economies of scale, EV-DO networks will start to fadeout. To keep the CDMA