Copyright © 2008 Fred Daneshgaran et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The explosive growth of multimedia applications over the Internet and the ever-increasing users'
demands over commercial terrestrial digital multimedia broadcasting all over
the world call for efficient physical and cross-layer techniques able to
mitigate the potential problems limiting broadband services over wireless networks.
In this scenario, mobile multimedia is expected to be one of the key services
of future wireless mobile networks. Meanwhile, recent advances in digital
communications have paved the way to a variety of standards aimed at providing multimedia
services over terrestrial broadband networks. For example, DVB-H, T-DVB, T-DMB,
wireless LANs, and wireless MANs are some of the most recent standards enabling
such technology.
Iterative decoding techniques for both source, channel, and joint source-channel coding
and decoding and cross-layering techniques have proven to be very effective for
providing a viable means of achieving capacity-approaching performance at very
reduced computational burden.
This special issue is aimed at highlighting state-of-the-art techniques on the most recent
research advances enabling digital multimedia services over broadband wireless
networks, focused on physical and cross-layering solutions.
The first paper “Lossy joint source-channel coding using raptor codes” by O. Y. Bursalioglu, M. Fresia, G. Caire, and H. V. Poor presents a joint source-channel coding scheme that
combines the advantages and simplicity of entropy-coded quantization with the
robustness of linear codes into a single linear encoding stage. Raptor codes
are exploited in order to guarantee a continuum of coding rates with a single
basic encoding algorithm.
The second paper “A simple scheme for belief propagation decoding of
BCH and RS codes in multimedia transmissions” by Marco Baldi and Franco
Chiaraluce proposes a new technique for decoding classic binary as well
as nonbinary codes through the use of the belief propagation algorithm, which
has proven to be effective in the decoding of low-density parity-check codes.
The focus of the paper is on Reed-Solomon codes included in the CDMA2000
standard.
The third paper “Design of a VLSI decoder for partially structured
LDPC codes” by Fabrizio Vacca, Libero Dinoi, and Guido Masera focuses on
the development of a new class of partially structured low-density parity-check
codes, and discusses the design of the VLSI decoder, as well as a novel
decoding technique called split decoding.
The fourth paper “Turbo decoder
for low power ultra-wideband communication systems” by Esam Obiedat, and Lei
Cao proposes a new method to reduce the computational complexity of
turbo decoding in ultra-wideband systems employing the orthogonal frequency
division multiplexing (OFDM) modulation. A bit-level stopping technique based
on the constrained decoding method is presented with the aim of detecting code
convergence on each OFDM subcarrier.
The fifth paper “System level evaluation of innovative
coded MIMO-OFDM systems for broadcasting digital TV,” by Youssef Nasser, Jean-Francois
Helard, and Matthieu Crussière investigates the application of
space-time codes in single frequency networks for digital TV broadcasting. A 3D
space-time-space block code is proposed in the context of the future
terrestrial digital TV systems using coded MIMO-OFDM techniques.
The sixth paper “Stationary
interference cancellation in upstream coordinated DSL using a turbo-MMSE receiver”
by Issam Wahibi, Meryem Ouzzif, Jérôme Le
Masson, and Samir Saoudi investigates the use of stationary interference
cancellation in upstream digital subscriber lines (DSLs) employing turbo-MMSE
techniques. The use of noise whitening techniques coupled with a mean-squared
error iterative receiver is proposed in order to approach the matched filter
bound of a DSL-coordinated system.
The seventh paper “Iterative
Mean Removal Superimposed Training for SISO and MIMO Channel Estimation” by
Omar Humberto Longoria-Gandara, Ramón Parra-Michel, Luis Miguel Bazdresch, and
Aldo Orozco describes a novel iterative radio channel estimation
algorithm based on a superimposed training estimation technique. The proposed
algorithm is well tailored to SISO as well as MIMO channels.
The eighth paper “Block
iterative/adaptive frequency-domain channel estimation for cyclic-prefixed single-carrier
broadband wireless systems” by Jong-Seob
Baek and Jong-Soo Seo presents a new block iterative/adaptive
frequency-domain channel estimation algorithm. The idea consists in iteratively
estimating the frequency response of the channel by employing a weighted element-wise
block adaptive frequency-domain channel estimation scheme that relies on the soft
information obtained by a soft-input soft-output decoder.
The last paper of this special issue “Real time communications in large scale wireless
networks” by Liang Song and Dimitrios Hatzinakos investigates the use of
large-scale cognitive networking methods in multihop wireless networks. Based
on the proposed method, data packets travel along opportunistic paths using
opportunistically available spectrum in every hop. The proposed algorithm is
key to guaranteeing quality of service in wireless mesh networks for broadband
networks supporting multimedia services, and visual sensor networks for
surveillance.
Acknowledgments
The authors are grateful to the reviewers for their invaluable work and to the authors of the
papers collected in this special issue.
Fred Daneshgaran
Massimiliano Laddomada
Marina Mondin