An adaptive quasi harmonic broadcasting scheme with optimal bandwidth requirement

The aim of Harmonic Broadcasting protocol is to reduce the bandwidth usage in video-on-demand service where a video is divided into some equal sized segments and every segment is repeatedly transmitted over a number of channels that follows harmonic series for channel bandwidth assignment. As the bandwidth of channels differs from each other and users can join at any time to these multicast channels, they may experience a synchronization problem between download and playback. To deal with this issue, some schemes have been proposed, however, at the cost of additional or wastage of bandwidth or sudden extreme bandwidth requirement. In this paper we present an adaptive quasi harmonic broadcasting scheme (AQHB) which delivers all data segment on time that is the download and playback synchronization problem is eliminated while keeping the bandwidth consumption as same as traditional harmonic broadcasting scheme without cost of any additional or wastage of bandwidth. It also ensures the video server not to increase the channel bandwidth suddenly that is, also eliminates the sudden buffer requirement at the client side. We present several analytical results to exhibit the efficiency of our proposed broadcasting scheme over the existing ones.Comment: IEEE International Conference on Informatics, Electronics & Vision (ICIEV), 2013, 6pages, 8 figure

Up-link performance of the DQRUMA MAC protocol in a realistic indoor environment for W-ATM networks

This paper evaluates by simulation the performance of the distributed queuing request update multiple access (DQRUMA) MAC protocol in a realistic indoor environment. This protocol has been simulated in conjunction with a type-II hybrid-ARQ protocol based on punctured R-S codes for the LLC layer. The analysis was carried out for a multicarrier modulation scheme (OFDM) with QPSK modulation on each carrier. The hidden Markov model (HMM) is used for modelling the physical layer of the system. The performance of the protocol in terms of throughput, mean delay, CLR and p.d.f. of the delay is presented. The pseudo-Bayesian algorithm as well as harmonic back-off are applied to calculate the retransmission probability for the backlogged users.Peer ReviewedPostprint (published version

Relativistic Positioning Systems

The theory of relativistic {\em location systems} is sketched. An interesting class of these systems is that of relativistic {\em positioning systems,} which consists in sets of four clocks broadcasting their proper time. Among them, the more important ones are the {\em auto-located positioning systems,} in which every clock broadcasts not only its proper time but the proper times that it receives from the other three. At this level, no reference to any exterior system (the Earth surface, for example) and no synchronization are needed. Some properties are presented. In the SYPOR project, such a structure is proposed, eventually anchored to a classical reference system on the Earth surface, as the best relativistic structure for Global Navigation Satellite Systems.Comment: 8 pages; 1 figure; to appear in Proc. Spanish Relativity Meeting ERE-2005, Oviedo (Spain); v2: minor formal change