Article

# Variable-Rate Two-Phase Collaborative Communication Protocols for Wireless Networks

Dept. of Electr. & Comput. Eng., Yokohama Nat. Univ.

IEEE Transactions on Information Theory (Impact Factor: 2.62). 10/2006; DOI: 10.1109/TIT.2006.880055 Source: IEEE Xplore

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**ABSTRACT:**Cooperative underwater acoustic communication systems come into prominence in recent years. Since underwater channels are sparse and additive noise entering the system is colored Gaussian noise. Therefore it is very difficult to estimate the underwater channels and theoretically makes it interesting. In this study, the transmission from source to the target recipient is realized by means of a relay system. Orthogonal frequency division multiplexing (OFDM)-based channel estimation problem is solved by using the matching pursuit (MP) algorithm and we obtained excellent error performance.01/2012; -
##### Conference Paper: Joint time offset and fading channel coefficient estimation for cooperative communication systems

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**ABSTRACT:**In this paper, we investigate joint channel gain and time offset estimation for two different data aided methods in cooperative communication with amplify-and-forward (AF) relaying. First one is the Cascaded Estimation (CE) method which channel gain, and time offset consisting of both source-to-relay, and relay-to-destination links are estimated at the destination terminal, second one is Disintegrated Estimation (DE) method which channel gain, and time offset are estimated seperately at the relay for source-to-relay link, and at the destination for relay-to-destination link. Both of the proposed joint estimators are based on Expectation-Maximization (EM) algorithm and, produce a low-complexity solution of itaretive maximum likelihood (ML) estimation. It was observed by the bit error rate (BER) curves, the proposed methods provide good performances with low-complexity.Signal Processing and Communications Applications Conference (SIU), 2013 21st; 01/2013 - [Show abstract] [Hide abstract]

**ABSTRACT:**This paper investigates the diversity-multiplexing tradeoff (DMT) performance of coded cooperation with incremental relaying (CCIR). First, the exact and closed-form DMT expression is derived for CCIR at arbitrary exchange ratio (ER), i.e., the ratio of the time duration of the first phase to that of the whole transmission phase. The result reveals that CCIR outperforms coded cooperation in terms of DMT. Compared with the slotted incremental decode-and-forward protocol, CCIR is more flexible in choosing ER, and performs better in DMT except for low multiplexing gain at high ER. Secondly, asymptotic power allocation, including both source and source-relay asymptotic power allocation, is carried out to improve the DMT performance under a long-term average power constraint. Finally, numerical results are provided to validate the analysis.Wireless Communications & Signal Processing (WCSP), 2012 International Conference on; 01/2012

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