THE design and the optimization of video communications over wireless networks is attracting a lot of attention from both academia and industry. The main challenge is to enhance the quality of service (QoS) support in terms of packet loss rate, end-to-end delay Distortion-Fair Cross-Layer Resource Allocation for Scalable Video Transmission in OFDMA Wireless Networks and minimum guaranteed bit-rate, while providing fairness where needed. The cross-layer approach, i.e., the exchange of information among different layers of the system, is one of the key concepts to be exploited to achieve this goal. Distortion-Fair Cross-Layer Resource Allocation for Scalable Video Transmission in OFDMA Wireless Networks In beyond-3G and 4G wireless system orthogonal frequency division multiple access (OFDMA) has been selected as a key physical (PHY) layer technology to support a very flexible access with high spectral efficiency. In order to exploit the available temporal, frequency and multi-user diversity, Distortion-Fair Cross-Layer Resource Allocation for Scalable Video Transmission in OFDMA Wireless Networks and to provide a given level of QoS, suitable adaptive resource allocation and scheduling strategies have to be implemented. Opportunistic schedulers, as for instance, proportional fair (PF) and maximum signal-to-noise ratio (SNR) schedulers, take advantage of the knowledge of the channel state information (CSI) in order to maximize the spectral efficiency. However, with these schedulers, the final share of throughput often results unfair, especially for the cell-edge users which suffer of data-rate limitations due to high Distortion-Fair Cross-Layer Resource Allocation for Scalable Video Transmission in OFDMA Wireless Networks path-loss and inter-cell interference. In real-time streaming the mismatch between the allocated PHY layer rate and the rate required by the delay-constrained application may cause the loss of important parts of the streams, which significantly degrades the end-user quality of experience (QoE). The provision of acceptableQoE to every user is enabled by the use of a scheduler at the medium access control (MAC) layer which delivers a fair throughput, according to specific utilities and constraints defined by the application. Moreover, the presence of an optimized source rate adaptation technique at the application (APP) layer becomes crucial to improve stability, to prevent buffer Distortion-Fair Cross-Layer Resource Allocation for Scalable Video Transmission in OFDMA Wireless Networks overflow and to maintain video play-back continuity. Rate adaptation is enabled by the use of video encoders that support multiple layers which can be sequentially dropped, thereby providing a graceful degradation. One of the most promising tool is the H.264 Advanced Video Coding (AVC) standard with scalable extension, also known as Scalable Video Coding.