Learn More
—This paper addresses user coexistence in cognitive radio systems by taking advantage of opportunities that arise during ARQ retransmission. It is shown that if these opportunities are properly exploited, nontrivial rates can be made available to a secondary (cognitive) pair while impinging little or no interference on the primary pair. This can be(More)
— This paper addresses the multiplexing loss that occurs in relay networks due to causality of relays and the half-duplex constraint. We devise relay selection methods to recover the multiplexing loss in decode-and-forward (DF) relay networks, while requiring very little feedback (merely bits/relay). Two network topologies are studied: First the case is(More)
— In this paper, we present a method for estimating the Doppler spread in mobile orthogonal frequency division multiplexing (OFDM) systems. The estimation is based on finding the autocorrelation function of time domain channel estimates over several OFDM symbols. In OFDM systems channel estimation is popularly performed in frequency domain. Channel(More)
—This paper investigates the degrees of freedom of the interference channel in the presence of a dedicated multiple-input multiple-output (MIMO) relay. The relay is used to manage the interference at the receivers. It is assumed that all nodes including the relay have channel state information only for their own links and that the relay has antennas in(More)
Relay networks face a fundamental challenge in terms of spectral efficiency, because relays must repeat the source information. To address this key problem, this paper presents two relay selection protocols that salvage spectral efficiency by adroitly leveraging the multiple relays. Both protocols have the feature of letting the source transmit all or most(More)
—We study a distributed protocol for time-division multiple access (TDMA) with applications in wireless body area networks. Our scheme is derived from a bio-inspired algorithm known as Pulse-Coupled Oscillator, in which each node in the network update its state based on its knowledge of the neighborhood. The protocol we propose is suitable for negotiation(More)