telephones or fixed computing platforms, such as desktop computers, that can access the Internet. The number of mobile devices is expected to continue to grow more rapidly than nomadic and stationary devices. Mobile terminals will be the most commonly used platforms for accessing and exchanging information. In particular, users will expect a dynamic, continuing stream of new applications, capabilities, and services that are ubiquitous and available across a range of devices using a single subscription and a single identity. Versatile communication systems offering customized and ubiquitous services based on diverse individual needs require flexibility in the technology in order to satisfy multiple demands simulta- neously. Wireless multimedia traffic is increasing far more rapidly than voice, and will increasingly dominate traffic flows. The paradigm shift from predominantly circuit-switched air interface design to full IP-based delivery has provided the mobile users with the ability to more efficiently, more reliably, and more securely utilize packet-switched services such as e-mail, file transfers, messaging, browsing, gaming, voice-over Internet protocol, location-based, multicast, and broadcast services. These services can be either symmetrical or asymmetrical (in terms of the use of radio resources in the downlink or uplink) and real-time or non real-time, with different quality of service requirements. The new applications consume relatively larger bandwidths, resulting in higher data rate requirements. In defining the framework for the development of IMT-Advanced and systems beyond IMT- Advanced radio interface technologies, it is important to understand the usage models and technology trends that will affect the design and deployment of such systems. In particular, the framework should be based on increasing user expectations and the growing demand for mobile services, as well as the evolving nature of the services and applications that may become available in the future. The trend toward integration and 