With the advancement of multimedia signal processing/compression technology and the wide deployment of wired/wireless networks, there is an increasing demand for multimedia communication services. Advanced multimedia processing often attempts to optimize the coding efficiency and introduces higher dependency among the processed data, resulting in a fundamental challenge to robust multimedia communications. On the other hand, modern communication networks offer multi-dimensional diversity, such as user, frequency, and location, and finer granularity of resources, such as power and spectrum, that have yet to be fully explored for improving the quality of multimedia communications. This special issue brings together the comprehensive survey of modern technologies and state-of-the-art research contributions that address the various aspects of multimedia communications, networking, and applications. In the first set of three invited survey articles, the authors review the related topics in the literature to articulate the observed technical issues and existing solutions.The first article, “Power-aware mobile multimedia: a survey” by Zhang et al, reviews the power management issues for video communication in a power-limited mobile device. Discussion on the characteristics of battery, video source coding, and communication system is presented. A general framework for power-aware cross-layer video delivery is then proposed to maximize the reconstructed video quality or minimize the consumed power. This article also discusses the challenges and future research directions in the field of power-aware mobile multimedia.The second article, “Reliable multimedia broadcasting over dense wireless ad-hoc networks” by Gau et al., presents a comprehensive survey of data dissemination schemes in wireless ad hoc networks, with the focus on broadcast applications. The paper reviews schemes on mitigating the broadcast storming problem as well as a Markov Chain model for analyzing the broadcast schemes proposed in the literature. Based on the analysis, an adaptive adjusted probabilistic scheme is proposed for improving the reliability of broadcasting in dense ad hoc networks.The third article, “Network Coding and Media Streaming” by Thomos and Frossard, surveys the recent research efforts on applying network coding principles to multimedia communication applications. The authors first overview the principles of practical network coding algorithms, describe the potentials of network coding in emerging delivery architectures, and then review the recent work on the application of network coding to media streaming applications. In addition, the challenges for multimedia streaming applications using network coding, such as delay and complexity constraints, are outlined.While systems involve multiple agents with different Quality of Service (QoS) requirements, limited system resources are shared by each user. Efficient and effective resource allocation methods are highly desired to utilize system resources to improve overall system service objectives. The second group of four articles addresses the multi-user resource allocation problem for multimedia over wireless networks in either centralized or decentralized manner.The forth article is entitled "Predictive spectrum access for multimedia users over multi-channel wireless networks" by Shiang et al. This article addresses the problem of channel selection in a decentralized multi-channel wireless network to maximize the multimedia quality. Different channel prediction models are evaluated under two different multiuser interaction scenarios; namely, non-collaborative and collaborative setting. An adaptive channel prediction algorithm is introduced for multimedia users based on the prediction bias and the type of other users.The fifth article, "Uplink power control in QoS-aware multi-service CDMA wireless networks" by Tsiropoulou et al., studies the power control problem in the uplink CDMA systems with QoS consideration to support both delay-sensitive and delay-tolerant users. A game-theoretic problem formulation is presented and a decentralized iterative algorithm is proposed to obtain the game’s equilibrium points.The sixth article, "QoE-driven cross-layer optimization for high speed downlink packet access" by Thakolsri et al., proposes a Quality of Experience (QoE) based cross-layer design framework to support multiple types of multimedia traffic simultaneously. Utility functions to describe the end-to-end QoE for different applications across different protocol layers are presented. Different optimization objectives with experimental results are evaluated to show the effectiveness of adaptation of QoE into the heterogeneous service system.The seventh article, "Optimization of multiservice scheduling for variable bit rate video transmission in DVB-H systems" by Striccoli et al., investigates the problem of transmitting multiple VBR video streams over DVB-H systems, given the constraints of receiver buffer size, available bandwidth and service priorities. The authors propose a window-based approach to optimally multiplex multiple video services by varying the burst durations to reduce possible data losses. The next two articles focus on the cross-layer design for multimedia communications in a single user scenario. More specifically, the eighth article in this special issue, "A MAC centric cross layer approach for H.264 video streaming over HSDPA" by Benayoune et al., examines MAC-level ARQ scheme for video streaming over HSDPA. The packet retransmission limit is adjusted based on different packet importance values inherited from hierarchically compressed video flows.The ninth article, "Always best packet switching: the mobile VoIP case study" by Ghini et al., focuses on improving VoIP quality for VoWLAN. Specifically, the authors focus on the scenario where a mobile device can utilize multiple transmission paths to deliver VoIP traffic. A cross-layer mechanism with adaptive transmission path selection and retransmission control subject to maximum acceptable end-to-end delay is proposed.Finally, the last paper of this special issue tackles the Internet infrastructure improvement issue. The article, "A measurement study on the benefits of open routers for overlay routing", by Tang et al., integrates the concepts of overlay routing and open routers, and studies the advantages of this scheme. The authors analyze the data collected from Planetlab nodes to illustrate the ability of open routers to enable better connectivity and enhance the end-to-end performance. Heuristic method for finding the locations of the open routers is also addressed.We would like to express our grateful thanks to all the authors who made submissions to this special issue, and to the many reviewers for their time and efforts to assist the decision process and to provide constructive feedback to the authors. We hope the papers in this special issue will provide an insightful overview of the existing literature and inspire new research ideas in multimedia communication, networking, and applications.