[Show abstract][Hide abstract] ABSTRACT: The wireless networks are notoriously error prone and all errors cannot be prevented in real-time communications. The problem of error correction becomes even more challenging in mobile multicast/broadcast applications. The mobile devices are being equipped with multiple modems that could work simultaneously; for example, devices with both GSM (WAN) and WLAN networks such as WiFi. These multi-modal devices can use the second network to improve their error resilience. We propose a P2P approach to establish and utilize an error recovery channel on a secondary network for multi-user video applications. The mobile devices within the vicinity can utilize the WLAN network to form a P2P network for error recovery purpose. We developed and evaluated three error recovery models for error recovery over secondary networks. The proposed models balance the response time, bandwidth utilization, fairness, and unnecessary data received
[Show abstract][Hide abstract] ABSTRACT: Mobile phone besides being communication device is being transformed to another role as an entertainment device. Mobile devices enable the user to access entertainment such as TV anywhere and not limit it to just homes. It is expected that the traditional broadcast multimedia content is multicast instead of unicast to the mobile users to conserve bandwidth. 3GPP is currently working on a standard for multimedia broadcast and multicast services (MBMS). This paper presents an intra-refresh based error resilience technique for video delivery over MBMS. We propose an adaptive intra block refresh rate technique based on the loss statistics from the multicast group and dynamically partitioning multicast groups. The proposed technique improves average PSNR of the received video for all the multicast groups
[Show abstract][Hide abstract] ABSTRACT: Mobile phones have become essential part of modern life and continue to change the way people communicate with each other. The camera phones have become ubiquitous in the recent past and video communication services such as videophone are getting rolled out by cellular providers. This would require video compression algorithms that are resilient to transmission errors and support resource-adaptive playback. We propose a video codec that addresses the two key issues in video delivery to mobile devices: (1) error resilience; and (2) resource adaptive playback. We show that the proposed codec is simple to implement on low-resource terminals such as mobile phones and outperforms MPEG-4 coding in terms of loss tolerance.
[Show abstract][Hide abstract] ABSTRACT: The popularity of mobile/wireless embedded systems running multimedia applications is growing. MPEG4 is an important and demanding multimedia application. With improved CPU, memory subsystem deficiency is the major barrier to improving the system performance. Studies show that there is sufficient reuse of values for caching to significantly reduce the raw required memory bandwidth for video data. Decoding MPEG4 video data in software generates many times more cache-memory traffic than required. Proper understanding of the decoding algorithm and the composition of its data set is obvious to improve the performance of such a system. The focus of this paper is to enhance MPEG4 decoding performance through cache optimization of a mobile device. The architecture we simulate includes a digital signal processor (DSP) to run the decoding algorithm and a two-level cache system. Level-1 cache is split into data (D1) and instruction (I1) caches and level-2 (CL2) is a unified cache. We use Cachegrind and VisualSim simulation tools to optimize cache size, line size, associativity, and levels of caches for a wireless device decoding MPEG4 video.