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In this paper, the analysis of an average received signal-to-noise ratio (SNR) for a cooperative communication network with amplify-and-forward (AF) relays is presented. In AF systems, the overall instantaneous SNR at the receiving end can be expressed as the form of a harmonic mean of perhop SNRs. This means that the received SNR can be analyzed by(More)
Hybrid relay systems using Amplify-and-Forward protocol (AF) and Decode-and-Forward protocol (DF) together are introduced in cooperative networks. For hybrid systems, we propose adaptive relay selection scheme to maximize the overall received Signal to Noise Ratio (SNR) at the destination. At first two relays are selected among many according to the(More)
We propose an improved timing estimation method for orthogonal frequency-division multiplexing (OFDM) systems that employ a preamble with time-domain repetitive patterns. The proposed method exploits the unique correlation property of the preamble including its cyclic prefix. Numerical results show that the proposed scheme is robust in fading multipath(More)
A novel method is proposed that can estimate the tag population in Radio Frequency Identification systems by using a Hadamard code for the sub-preamble of the tag response. We formulate the maximum likelihood estimator for the tag population using a given number of the observed footprints. In simulations, the proposed estimator performs considerably better(More)
An adaptive resource assignment scheme for the multi-user cooperative communication systems with amplify-and-forward (AF) relays is investigated. We consider maximizing system capacity while guaranteeing the QoS (Quality of Service) of each user. A resource assignment is proposed using space-time coding with only source-to-relay channel gain information(More)
An adaptive relay allocation scheme for multi-user cooperative communication systems with amplify-and-forward (AF) relays is investigated. We consider maximizing system capacity while guaranteeing the QoS (Quality of Service) of each user. Proposed relay allocation scheme uses space-time coding technique. It performs well in allocating relay nodes to(More)