Evaluation of the H.264 scalable video coding in error prone IP networks

The Joint Video Team, composed by the ISO/IEC Moving Picture Experts Group (MPEG) and the ITU-T Video Coding Experts Group (VCEG), has standardized a scalable extension of the H.264/AVC video coding standard called Scalable Video Coding (SVC). H.264/SVC provides scalable video streams which are composed by a base layer and one or more enhancement layers. Enhancement layers may improve the temporal, the spatial or the signal-to-noise ratio resolutions of the content represented by the lower layers. One of the applications, of this standard is related to video transmission in both wired and wireless communication systems, and it is therefore important to analyze in which way packet losses contribute to the degradation of quality, and which mechanisms could be used to improve that quality. This paper provides an analysis and evaluation of H.264/SVC in error prone environments, quantifying the degradation caused by packet losses in the decoded video. It also proposes and analyzes the consequences of QoS-based discarding of packets through different marking solutions.

IB-DFE receiver techniques for CP-assisted block transmission within DS-CDMA and MC-CDMA systems

MC-CDMA (MultiCarrier Code Division Multiple Access), currently regarded as a promissing multiple access scheme for broadband communications, is known to combine the advantages of an OFDM-based (Orthogonal Frequency Division Multiplexing), CP-assisted (Cyclic Prefix) block transmission with those of CDMA systems. Recently, it was recognised that DS-CDMA (Direct Sequence) implementations can also take advantage of the beneficts of the CP-assisted block transmission approach, therefore enabling an efficient use of FFT-based (Fast Fourier Transform), chip level FDE (Frequency- Domain Equalisation) techniques. In this paper we consider the use of IB-DFE (Iterative Block Decision Feedback Equalisation) FDE techniques within both CP-assisted MC-CDMA systems with frequency-domain spreading and DS-CDMA systems. Our simulation results show that an IB-DFE receiver with moderate complexity is suitable in both cases, with excellent performances that can be close to the single-code matched filter bound (especially for the CP-assisted DSCDMA alternative), even with full code usage.

A frequency-domain receiver for asynchronous systems employing CP-assisted DS-CDMA schemes

In this paper we consider the uplink transmission within CP-assisted (Cyclic Pre¯x) DS-CDMA (Direct Sequence Code Division Multiple Access) systems and we present a frequency-domain MUD (MultiUser Detection) receiver with iterative estimation and compensation of residual frequency errors. The proposed receiver is suitable for broadband wireless systems, with performances that can be close to the single-user MFB (Matched Filter Bound), even for fully loaded systems and/or in the presence of strong interfering signals. The receiver is powerful enough for typical asynchronous scenarios, requiring only a coarse synchronization between users.

SIC and PIC multiuser detection for prefix-assisted DS-CDMA systems

In this paper we present iterative frequency-domain multiuser detection (MUD) receivers for the uplink transmission of direct sequence code division multiple access systems (DS-CDMA) that combine iterative block decision feedback equalization (IB-DFE) principles with interference cancelation techniques. Both successive interference cancelation (SIC) and parallel interference cancelation (PIC) structures are considered. Our performance results show that the proposed receiver structures have excellent bit error rate (BER) performances, that can be close to the single-user matched filter bound (MFB), even for fully loaded systems and severely time-dispersive channels1.