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Cooperative diversity has been recently proposed as a way to form virtual antenna arrays that provide dramatic gains in slow fading wireless environments. However most of the proposed solutions require distributed space-time coding algorithms, the careful design of which is left for future investigation if there is more than one cooperative relay. We(More)
— In this paper, we present simple opportunistic relaying with decode-and-forward (DaF) and amplify-and-forward (AaF) strategies under an aggregate power constraint. In particular , we consider distributed relay-selection algorithms requiring only local channel knowledge. We show that opportunistic DaF relaying is outage-optimal, that is, it is equivalent(More)
— In this paper, we present single-selection— opportunistic—relaying with decode-and-forward (DaF) and amplify-and-forward (AaF) protocols under an aggregate power constraint. We show that opportunistic DaF relaying is equivalent to the outage bound of the optimal DaF strategy using all potential relays. We further show that opportunistic AaF relaying is(More)
— Practical cooperative diversity protocols often rely on low-cost radios that treat multiple in-band signals as noise and thus require strictly orthogonal transmissions. We analyze the performance of a class of opportunistic relaying protocols that employ simple packet level feedback and strictly orthogonal transmissions. It is shown that the(More)
— In this paper, we show that optimal selection and transmission of a single relay among a set of multiple amplify-and-forward (AF) candidates minimize the outage probability (i.e., outage-optimal) and outperform any other strategy that involves simultaneous transmissions from more than one AF relay under an aggregate power constraint. This outage(More)
—This work evaluates opportunistic relaying in the presence of thermal noise as well as interference, when channel sensing is conducted reactively, in slow fading environments. The studied scenario employs a single gateway that provides access towards several destinations with weak links and exploits a network of intermediate relays. In sharp contrast to(More)
—Backscatter radio is proposed for sensor networks. In that way, the transmitter for each sensor is simplified to a transistor connected to an antenna and therefore, the cost for each sensor's communicator becomes negligible, while energy used for wireless communication per sensor is minimized. A software-defined transceiver is built to transmit a carrier,(More)
—This work derives and evaluates single-antenna detection schemes for collided radio frequency identification (RFID) signals, i.e. simultaneous transmission of two RFID tags, following FM0 (biphase-space) encoding. In sharp contrast to prior art, the proposed detection algorithms take explicitly into account the FM0 encoding characteristics, including its(More)
—Scatter radio achieves communication by reflection and requires low-cost and low-power RF front-ends. However, its use in wireless sensor networks (WSNs) is limited, since commercial scatter radio (e.g. RFID) offers short ranges of a few tens of meters. This work redesigns scatter radio systems and maximizes range through non-classic bistatic(More)