Link adaptation, in particular adaptive coded modulation (ACM), is a promising tool for bandwidth-efficient transmission in a fading environment. The main motivation behind employing ACM schemes is to improve the spectral efficiency of wireless communication systems. In this paper, using a finite number of capacity achieving component codes, we propose new transmission schemes employing constant power transmission, as well as discrete- and continuous-power adaptation, for slowly varying flat-fading channels. We show that the proposed transmission schemes can achieve throughputs close to the Shannon limits of flat-fading channels using only a small number of codes. Specifically, using a fully discrete scheme with just four codes, each associated with four power levels, we achieve a spectral efficiency within 1dB of the continuous-rate continuous-power Shannon capacity. Furthermore, when restricted to a fixed number of codes, the introduction of power adaptation has significant gains with respect to average spectral efficiency and probability of no transmission compared to a constant power scheme.
|EURASIP Journal on Wireless Communications and Networking
|Published - 2008
Bibliographical noteFunding Information:
The Project Wonderland is supported by Darkstar and jVoiceBridge for distribution of multimedia information. Project Wonderland technology visualizes information in 3D by showing dynamically generated 3D graphics. Darkstar gives it ability to run on large servers and support massive databases, and jVoiceBridge handles audio communication (VoIP).The proposed enriching cyberspace or enriching Web is based on assessing situations of remote users through fusing information of multiple biological sensors and the related user profile. Our approach is evaluated by checking if the cyberspace environment of the Project Wonderland can be enriched to prevent/deal with misunderstandings in web-based collaborative systems, using multiple biological sensors that are handy in operation and reasonable in cost for web users.
ASJC Scopus subject areas
- Signal Processing
- Computer Science Applications
- Computer Networks and Communications