Transmission of 3D Scenes over Lossy Channels

This paper introduces a novel error correction scheme for the transmission of three-dimensional scenes over unreliable networks. We propose a novel Unequal Error Protection scheme for the transmission of depth and texture information that distributes a prefixed amount of redundancy among the various elements of the scene description in order to maximize the quality of the rendered views. This target is achieved exploiting also a new model for the estimation of the impact on the rendered views of the various geometry and texture packets which takes into account their relevance in the coded bitstream and the viewpoint required by the user. Experimental results show how the proposed scheme effectively enhances the quality of the rendered images in a typical depth-image-based rendering scenario as packets are progressively decoded/recovered by the receiver

GORA: Goodput Optimal Rate Adaptation for 802.11 using Medium Status Estimation,”

Abstract-Rate Adaptation for 802.11 has been deeply investigated in the past, but the problem of achieving optimal Rate Adaptation with respect not only to channel-related errors but also to contention-related issues (i.e., collisions and variations in medium access times) is still unsolved. In this paper we address this issue by proposing 1) a practical definition of the Medium Status in a multi-user 802.11 scenario in terms of channel errors, MAC collisions and packet service times, and a method for its estimation based on measurements; 2) an analytical model of the goodput performance as a function of the Medium Status; 3) a rate adaptation algorithm, called Goodput Optimal Rate Adaptation (GORA), which is based on this model. Unlike other Rate Adaptation schemes proposed in literature, which require either modifications to the IEEE 802.11 standard or cooperation among nodes, GORA is totally stand-alone and standard compliant. In fact, the Medium Status Estimation used by GORA is obtained by using standard MAC counters that are commonly collected by commercial MAC drivers, and no explicit interactions with the other devices in the network is required. Therefore, GORA offers the advantage of being readily deployable on real devices. The performance of GORA is evaluated through NS2 simulations which reveal that, as expected, GORA outperforms other wellknown Rate Adaptation algorithms in several scenarios and can be used as a new reference benchmark

Efficient collision detection for auto rate fallback algorithm

The physical rate adaptation in 802.11 is a deeply investigated, though still open issue. Since 802.11 uses the random access Distributed Coordination Function (DCF) mechanism to access the medium, collisions can occur when two or more stations want to transmit data simultaneously. The challenge of rate adaptation schemes is to adapt the physical transmission rate based on channel-related losses, i.e. collisions should not influence the choice of the rate. In this paper we propose a new rate adaptation algorithm that behaves like Auto Rate Fallback (ARF), but makes use of the RTS/CTS handshake, when necessary, to decide whether the physical transmission rate should be changed. Main advantages of this algorithm are its simple implementation and the good performance it attains in presence of collisions. We evaluate the performance of this new rate adaptation algorithm, comparing it with other well known algorithms, by using the new NS–3 simulator.

A CrossLayer Solution for VoIP over IEEE802.11

A dynamic and distributed multiuser radio resource allocation scheme for a FDMA-TDMA based multicellular system is proposed. User interference measurements and channel estimation at the mobiles are used in order to exploit the multiuser diversity of the system. Basic information bearers (i.e. the subcarrier/time-slot pairs) are efficiently allocated and power loaded to accommodate the users rate-demands and dynamically adapt to the interference produced by neighboring cells. Our solution leverages on the possibility to feed the RRM algorithm with parameters coming from different layers, following a cross-layer approach. A CrossLayer Solution for VoIP over IEEE802.11 | Request PDF. Available from: https://www.researchgate.net/publication/239680232_A_CrossLayer_Solution_for_VoIP_over_IEEE80211 [accessed Aug 08 2018]