Evgeny Bakin

Analysis of energy harvesting efficiency for power supply of WBAN nodes in heterogeneous scenarios

The paper provides a through analysis of electromagnetic fields harvesting efficiency. We show that harvesting of energy only from ambient sources implies significant limitations in applications with strong QoS requirements, such as modern wireless body-area networks (WBANs). The joint usage of ambient and dedicated sources can enhance the capabilities of EH-supplied WBANs. We also discuss the influence of various additional parameters on overall system performance (e.g. carrier frequency, WBAN mounting way, user movement pattern etc.). The obtained results are based on both laboratory measurements and simulations.

Lower bound of mean user waiting/watching time ratio in wireless video streaming networks

We consider centralized wireless networks for users of video streaming services. If the network is congested, wireless channel resources can be insufficient to satisfy all user requests. In this case QoE with some users may heavily degrade (video playback may periodically interrupt due to rebuffering effect, or startup buffering can take an intolerably long time). These negative effects can be partly reduced by appropriate scheduling of radio resources of the network. In the paper we propose a lower bound for the mean user waiting time spent on startup buffering and rebufferings in all possible schedulers. Through asymptotic analysis and simulation, this bound is compared with the results of a few generic scheduling policies. The proposed bound can be used as a basic performance test for existing and new algorithms of radio resources management in wireless video streaming networks.

Analysis of capacity of picocell with dominating video streaming traffic

This paper focuses on the research of centralized wireless networks where main load is formed with on-line video streaming services. In case of congestion channel resources are not enough for satisfying all the users requirements. This brings to degradation of video playback (appearance of rebufferings, forced transcoding to lower bit rate etc). Congestion has probabilistic nature, since it depends not only on number of users but also on there location relatively to a base station and chosen bit rates of videos. For considered networks we propose a model and two techniques of congestion probability estimation. Basing on these estimations network capacity is analyzed.

Average Delay Estimation in Discrete-Time Systems with Periodically Varying Parameters

In this paper, we consider communication systems with periodically varying parameters, such as success probability when a user requests service. These systems may be described by a Markov chain of a cyclic structure. We concentrate on investigating the average delay value in such systems. In the general case, a direct solution is given with its complexity being linear of the number of Markov chain states. For the case when the parameters of a system are varying slowly, a fast algorithm of the average delay calculation is proposed. Some applications of our results to contemporary communication systems are demonstrated.

Improved sum rate estimation for one coding scheme in S-user vector adder channel

In this work we analyze a coding scheme for an S-user multiple access channel proposed in [1]. For this scheme we consider a maximum likelihood receiver and find a closed-form expression for an upper bound of its error rate. Basing on this result we propose improved sum rate estimation for the scheme.

Scheduling algorithms for tree-based convergecast networks with a random number of messages

In the paper we consider tree-based L-level convergecast networks, in which leaf nodes correspond to data sources (DS), a root node - to a base station (BS), and other nodes - to intermediate repeaters (IR). At a startup phase each DS generates a random number of messages for transmission to a BS. For such a model a lower bound for an average duration of collision-free convergecast is given. Also we propose a collision-free messages transmission scheduling algorithms for which the lower bound is achieved at L → ∞.

Crosstalk-Steady Receivers for Small-Scale WCAN Networks

In the paper we consider small-scale wireless chip-area network (WCAN), consisting with a few couples of simplex communicating devices. In WCAN ultra-wideband technologies are usually used. Since all the couples operate in one frequency band performance of such communication system can sufficiently suffer from crosstalk. We proposed two receivers, named Maximum A-Posteriori (MAP) and Max-Log-MAP, considering crosstalk structure. Simulation results show, that usage of proposed receivers can significantly increase maximum date rate in the system comparing to conventional correlation receiver.

Load balancing routing algorithm for data gathering sensor network

Data gathering sensor network is considered in the paper. In these networks each node is used both as source of data and as retransmitter of packets, going from other nodes. A few important parameters of sensor network (such as lifetime, data rate, channel utilization etc.) depend on chosen routing scheme. Incorrectly chosen scheme results in appearance of bottle-necks, which can highly delay data transmission and lead to rapid battery discharge of particular nodes. In this paper we propose routing scheme for convergecast sensor networks, which decreases number of bottle-necks. Effectiveness of proposed algorithm is shown via simulation.