in the form of revisions. Further, the OFDM physical layer used by WiMAX is more amenable to MIMO implementations than are CDMA systems from the standpoint of the required complexity for comparable gain. OFDM also makes it easier to exploit frequency diversity and multiuse diversity to improve capacity.
uplink data rate ratios. Typically, 3G systems have a fixed asymmetric data rate ratio between downlink and uplink. What about in terms of supporting advanced IP applications, such as voice, video, and multimedia?
How do the technologies compare in terms of prioritizing traffic and controlling quality? The WiMAX media access control layer is built from the ground up to support a variety of traffic mixes, including real-time and non-real-time constant bit rate and variable bit rate traffic, prioritized data, and best-effort data. Such 3G solutions as HSDPA and 1x EV-DO were also designed for a variety of QoS levels. Perhaps the most important advantage for WiMAX may be the potential for lower cost owing to its lightweight IP architecture. Using an IP architecture simplifies the core network— 3G has a complex and separate core network for voice and data—and reduces the capital and operating expenses.