Muhammad Fainan Hanif

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—In this paper we describe a model for calculating the aggregate interference encountered by primary receivers in the presence of randomly placed cognitive radios (CRs). We show that incorporating the impact of distance attenuation and lognor-mal fading on each constituent interferer in the aggregate, leads to a composite interference that cannot be(More)
—In this paper we consider the capacity of the cog-nitive radio (CR) channel in a fading environment under a " low interference regime ". This capacity depends critically on a power loss parameter, α, which governs how much transmit power the CR dedicates to relaying the primary message. We derive a simple, accurate approximation to α which gives(More)
The problem of maximizing weighted sum rates in the downlink of a multicell environment is of considerable interest. Unfortunately, this problem is known to be NP-hard. For the case of multi-antenna base stations and single antenna mobile terminals, we devise a low complexity, fast and provably convergent algorithm that locally optimizes the weighted sum(More)
—In this paper we describe the effect of imperfections in the radio environment map (REM) information on the performance of cognitive radio (CR) systems. Via simulations we explore the relationship between the required precision of the REM and various channel/system properties. For example, the degree of spatial correlation in the shadow fading is a key(More)
The important problem of weighted sum rate maximization (WSRM) in a multicellular environment is intrinsically sensitive to channel estimation errors. In this paper, we study ways to maximize the weighted sum rate in a linearly precoded multicellular downlink system where the receivers are equipped with a single antenna. With perfect channel information(More)
—In this paper we consider the problem of signal-to-interference-plus-noise ratio (SINR) balancing in the downlink of cognitive radio (CR) networks while simultaneously keeping interference levels at primary user (PU) receivers (RXs) below an acceptable threshold with uncertain channel state information available at the CR base-station (BS). We optimize the(More)