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In multiple-relay cooperative wireless networks, opportunistic relaying is a promising scheme, where the most challenging problem is to choose the best relay efficiently. The traditional opportunistic relay selection scheme is based on the channel conditions of source-relay (S-R) and relay-destination (R-D) links. In comparison with conventional narrowband networks, an appealing merit of impulse radio...
In this paper, we analyze the bit error rate (BER) performance of a single relay selection with network coding (S-RS-NC) scheme in two-way relay channels. In this scheme, two source nodes first broadcast their information to the relays sequentially. A single relay which optimizes the system performance is selected. The selected relay decodes the received signals from two sources, performs network...
In this paper, a cooperative system with two users and one relay is considered. An amplify-and-forward relaying protocol is applied in a half duplex mode. To make the transmission delay as short as possible, the relay forwards for both users simultaneously. We consider transmission schemes with symbol rates 2/3 to demonstrate the tradeoff among performance, delay, and symbol rate. Based on the analysis...
Adaptive modulation has been widely adopted in broadband wireless communication systems to improve spectrum efficiency. On the other hand, user cooperative diversity has been investigated to improve system coverage and efficiency. How to take the advantage of adaptive modulation for user cooperative transmissions to maximize network throughput under the constraint of the bit error rate (BER) requirement...
This paper considers a cooperative network in which binary frequency-shift-keying (BFSK) modulation is employed to facilitate noncoherent communications between a source and a destination with the help of K relays. Proposed is an adaptive cooperative scheme that employs two thresholds as follows. One threshold is used to select retransmitting relays: a relay retransmits to the destination if its decision...
In this paper we propose a relay selection scheme which uses collected location information together with a path loss model for relay selection, and analyze the performance impact of mobility and different error causes on this scheme. Performance is evaluated in terms of bit error rate by simulations. The SNR measurement based relay selection scheme proposed earlier is unsuitable for use with fast...
Recently developed cooperative protocol with distributed path selection provides a simple and practical means of achieving full cooperative diversity in wireless networks. While the best path selection method can significantly improve bit error rate (BER) performance, it may cause unequal power consumption among relay nodes, which may reduce the lifetime of energy-constrained networks. A path selection...
In order to improve the communication efficiency without using multi-antennae terminals, cooperative communications implement one or several single antenna relays to assist the transmission between a source and a destination. The design of such a cooperative network, involves several layers of the OSI model. Transmission and multiplexing techniques are addressed at the physical layer whereas the management...
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