Dereje H. Woldegebreal

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In wireless networks, cooperative transmission is used as a means to combat channel fading. In this system, a source and a relay transmit each others' messages to a common destination using either amplify-and-forward or decode-and-forward strategies; the protocols in cooperative transmission can also broadly be categorized as static and adaptive. The idea(More)
The multiple-access relay channel (MARC) based on network coding has been proposed in recent papers as a means to achieve diversity gain in wireless networks, at the same time reducing the number of transmissions by a relay node. In MARC, multiple sources transmit to a common destination with the assistance of a single relay. In a network-coding-based(More)
For block-fading Rayleigh channels, this work considers a network coding approach to cooperative transmission. The network under consideration consists of two sources, S and P, that transmit to a common destination, D. Using halfduplex channels, S and P transmit their packets to D; they also overhear each other’s transmission. Then both sources cooperate by(More)
In cooperative transmission users are allowed to share antennas to transmit their messages to a common destination. Users employ either amplify-and-forward or decodeand-forward strategies to forward each others’ messages. In network-coding-based cooperative transmission schemes, users are allowed to combine their own and their partner’s message by a(More)
In Wireless Sensor Networks large number of nodes and limited energy available per node calls for designing efficient transmission protocols. Cooperative transmission is one of the protocols which helps wireless nodes to achieve spatial diversity, which translates into reduction in transmission power or increase in coverage area. Cooperative protocol can be(More)
Bit-wise XOR network coding has been shown to perform well in cooperative wireless transmission because of its simple coding operation and overall robustness increase due to combining of several messages. Our aim is to develop a cooperation protocol that uses basic and easy to implement operations but still combines the messages well and achieves good(More)
In Wireless Sensor Networks, designing energy efficient transmission protocols is a key requirement. Network-coded cooperation allows wireless nodes to exploit spatial diversity by relaying received messages, which reduces transmission energy or increases communication reliability. However, relaying redundant messages consumes considerable energy at(More)
This work presents an energy efficiency (EE) investigation of a beam generated by the combination of Recursive Least Square (RLS) algorithm and Kaiser side lobe cancellation technique in smart antenna system. The RLS-Kaiser combination is investigated using energy model which is a function of beam width, range and signal to noise plus interference ratio(More)
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