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- Kumar, A., et al.
(författare)
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A Scalable Feedback Mechanism for Distributed Nullforming with Phase-Only Adaptation
- 2015
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Ingår i: IEEE Transactions on Signal and Information Processing over Networks. - : Institute of Electrical and Electronics Engineers Inc.. - 2373-776X. ; 1:1, s. 58-70
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Tidskriftsartikel (refereegranskat)abstract
- This paper considers a problem of distributed nullforming, in which multiple wireless transmitters steer a null toward a designated receiver by only adjusting their carrier phases. Since each transmitter transmits at full power, the system maximizes 'power pooling' gains for cooperative communication or jamming, while simultaneously protecting a designated receiver. Analysis in a noiseless setting shows that, while the received power at the designated receiver, as a function of the transmitted phases, is nonconvex with multiple critical points, all of its local minima are also global minima. This implies that a null can be formed using a distributed, scalable protocol based on gradient descent: each transmitter adapts its phase based only on aggregate feedback broadcast by the receiver (so that feedback overhead does not increase with the number of transmitters), along with an estimate of its own channel gain (which can be obtained, e.g., via reciprocity). Simulations show that the convergence rate actually improves with the number of transmitters, and that the algorithm is robust to noise, substantial channel estimation errors, and oscillator drift.
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- Rahman, Mohammad Mahboob Ur, et al.
(författare)
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Simultaneous Energy Harvesting and Sender-Node Authentication at a Receiver-Node
- 2015
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Ingår i: Ubiquitous Wireless Broadband (ICUWB), 2015 IEEE International Conference on. - : IEEE conference proceedings. ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- We consider a system with three single-antenna nodes; Alice talks to Bob over a time-slotted AWGN channel, while Eve's objective is to impersonate Alice. We then consider a setting where, for every received packet, Bob needs to do simultaneous energy harvesting (EH) and sender-node authentication. To this end, Bob employs frequency offset as the decision metric for binary hypothesis testing based authentication framework. Then, assuming separate receive chains for energy harvesting and information decoding, Bob implements two deterministic energy harvesting schemes: i) time-switching (TS) based, ii) static power-splitting (SPS) based. For both EH schemes, we analyze the trade-off between detection performance of the authentication scheme and amount of energy harvested. Numerical results suggest that for the same detection performance, SPS scheme outperforms TS scheme in terms of amount of energy harvested. We also consider a random energy harvesting scheme, the so-called opportunistic EH scheme, whereby Bob utilizes Eve's packets (as labeled by authentication scheme) to harvest energy. There, it is straightforward to see that the normalized mean throughput of EH receive chain increases linearly with an increase in Eve's attack rate.
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