We consider an AWGN multiple access channel in which two correlated senders send information to a common receiver. In order to reduce the required transmission power, each one of the senders is encoded independently using a standard turbo code. The correlation model is not assumed to be known at the encoder. The decoder consists of two turbo decoders, each associated to a different sender, which exchange extrinsic information to exploit the correlation existing between the senders. The resulting performance is close to the theoretical limits obtained when separation between source and channel coding is assumed. This occurs even when the correlation between senders and the noise variance are unknown at the decoder site, since they can be estimated jointly with the decoding process with little performance degradation.
Digital transport capabilities to a home served by a fiber-to-the-curb network are limited by the transmission characteristics of the twisted-pair drop cable. However, advanced digital signal processing techniques can substantially increase the data transmission capability over the relatively short lengths of these metallic sections. The purpose of this study is to estimate the maximum achievable information rate versus drop cable length (between 100 to 500 meters), when very high rate asymmetric digital subscriber line (VADSL) modems, with a QAM modulation technique, are used. Different QAM constellations have been analyzed and two types of disturbances have been considered: far-end crosstalk (FEXT) and additive white Gaussian noise (AWGN). Simulation results show that FEXT is a greater impairment than AWGN, and that a 16-QAM constellation outperforms any other number.
Conference Committee Involvement (1)
Internet Quality of Service
9 September 2003 | Orlando, Florida, United States
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.