Browsing by Subject "Encoding (symbols)"

Now showing 1 - 3 of 3

Open Access
Binary morphological subband decomposition for image coding
(IEEE, 1996) Gürcan, Metin Nafi; Gerek, Ömer Nezih; Çetin, A. Enis
In this paper a binary waveform coding method based on morphological subband decomposition coupled with embedded zero-tree and entropy coding is described. This method can be utilized in text compression or bit-plane coding of images. Binary morphological subband decomposition operations are carried out in the Gallois Field, resulting in a computationally efficient structure. Simulation studies are presented.
Open Access
Noncoherent space-time coding: an algebraic perspective
(IEEE, 2005-06) El Gamal, H.; Aktas, D.; Damen, M. O.
The design of space-time signals for noncoherent block-fading channels where the channel state information is not known a priori at the transmitter and the receiver is considered. In particular, a new algebraic formulation for the diversity advantage design criterion is developed. The new criterion encompasses, as a special case, the well-known diversity advantage for unitary space-time signals and, more importantly, applies to arbitrary signaling schemes and arbitrary channel distributions. This criterion is used to establish the optimal diversity-versus-rate tradeoff for training based schemes in block-fading channels. Our results are then specialized to the class of affine space-time signals which allows for a low complexity decoder. Within this class, space-time constellations based on the threaded algebraic space-time (TAST) architecture are considered. These constellations achieve the optimal diversity-versus-rate tradeoff over noncoherent block-fading channels and outperform previously proposed codes in the considered scenarios as demonstrated by the numerical results. Using the analytical and numerical results developed in this paper, nonunitary space-time codes are argued to offer certain advantages in block-fading channels where the appropriate use of coherent space-time codes is shown to offer a very efficient solution to the noncoherent space-time communication paradigm.
Open Access
A simulation study of forward error correction for lost packet recovery in B-ISDN/ATM
(IEEE, 1993-05) Oğuz, Nihat Cem; Ayanoğlu, E.
We present the results of a simulation study for a virtual circuit connection over an ATM network where forward error correction is performed at both the ATM cell level and the packet data unit (PDU) level. A main conclusion of this study is that at low loads ATM cells from the same source dominate in the switch buffers, while at high loads there is a mixing of ATM cells from different sources. For the latter case. ATM cell level coding performs better, while for the former, PDU level coding performs better. The combination of the two techniques has the best overall performance.