[show abstract][hide abstract] ABSTRACT: Practical implementation of video compression for distributed sources is currently an active research area. The distributed compression paradigm based on the Slepian-Wolf model has been proposed for low-complexity video compression algorithms and energy efficient wireless sensor networks. In this paper, we consider a joint source-channel resource allocation for sensor network applications based on the Slepian-Wolf paradigm in fading channel environments. The sensor nodes are modeled as a multiuser uplink channel transmitting correlated information. We study an efficient distributed constant bit rate allocation scheme based on the Slepian-Wolf model operating in a multiaccess wireless channel.
Personal, Indoor and Mobile Radio Communications, 2008. PIMRC 2008. IEEE 19th International Symposium on; 10/2008
[show abstract][hide abstract] ABSTRACT: To provide reliable real-time video services in a wireless multipath-fading system, large modifications in transmitting power would be necessary to counteract the extreme variations in channel quality. However, with the availability of diversity such as receiver diversity or multiple channels as in MIMO systems, one can ldquosmooth outrdquo these channel fluctuations, making it possible to support a reliable bit rate channel with efficient power control. Our goals in this work are the following. First to demonstrate a real-time implementable physical layer solution. Second to utilize this physical layer solution along with a practical video encoder to demonstrate the feasibility of a robust real-time cross-layer solution which allows seamless interaction between the application layer and the physical layer to provide a reliable video service. The solution we propose not only makes maximum use of available channel capacity but also makes the best possible use, in real-time, of the compressed video information.
[show abstract][hide abstract] ABSTRACT: This paper focuses on the design of the cross layer between the video application layer and the MIMO physical layer. MIMO
physical layer research has promised an enormous increase in the capacity of wireless communication systems. Also MIMO wireless
systems operate under fading conditions where the channel faces arbitrary fluctuations. Since the wireless channel changes
over each coherence period, the capacity of the wireless channel, given the power constraints, changes. Hence to make efficient
use of the available capacity one needs to adapt the video bit rate. However it is impossible to adapt at the application
layer as changing the parameters of the video takes more time than the coherence period of the channel. In this paper we address
this problem through a novel solution and also investigate its performance through a simulation study.
Journal of Zhejiang University - Science A: Applied Physics & Engineering 09/2006; 7(10):1690-1694. · 0.53 Impact Factor
[show abstract][hide abstract] ABSTRACT: High quality, real-time wireless multimedia services becomes a reality in the future. A major application area is the video tele-presence service, which requires real-time interactive video support over the wireless channel. Video coding and wireless physical layer have been largely developed with little consideration for each other. Video encoder design aims to provide the highest possible encoding quality at the cost of degrading error resilience capability, while wireless physical layer technologies aim to maximize channel capacity. However, since conventional video rate control schemes cannot respond to the sudden capacity fluctuation of the wireless channel, any increase in wireless channel capacity goes unutilized by the video application. In this paper we address this issue by specifically developing a cross-layered solution. Specifically we utilize MIMO technology to guarantee a certain QoS and employ a video layer technology that capitalizes on the available capacity at the physical layer in real-time.
Wireless Networks, Communications and Mobile Computing, 2005 International Conference on; 07/2005
[show abstract][hide abstract] ABSTRACT: Supporting high-quality video transmission across wireless networks demands not only high but also constant bit rate (CBR). In order to provide a CBR channel, large modifications in transmitting power requirement would normally be necessary to inverse extremely high variation in channel fading. However, with a multiple input and multiple output (MIMO) system, sub-channel diversity can "smooth out" aggregate channel fluctuation, making it possible to support a CBR channel with efficient power control. We have devised an optimal antenna transmitting power and bits-per-symbol allocation algorithm that can reduce significantly, the total power consumption required to maintain CBR channels. We also utilize a secondary power control based on leaky bucket paradigm for smooth battery drain and to make peak power utilization to within system requirements. Simulation results reveal that under practical power fluctuation constraints, the scheme can achieve power savings of up to 10 dB with a 4×4 antenna system.
[show abstract][hide abstract] ABSTRACT: Wireless channels provide an extremely challenging scenario to support quality data and multi-media services. In this paper, we consider the scenario of supporting vector delay-limited wireless multimedia services such as Constant Bit Rate (CBR) wireless video, where certain desired amount of data need to be transmitted through a vector channel within a given delay. We focus on the problem of energy minimization under target delay-limited rate and bit error rate constraints. We develop an adaptive modulation scheme for single user wireless systems for generic vector wireless communications systems model. In this paper we extend previous works on this problem to provide a recursive closed form solution that reduces memory requirements and make it suitable for real-time deployments. Through simulations we find improvements in average bit energy as we increase the delay.