This work considers the uplink of a Massive MIMO network wherein the base stations (BSs) are randomly deployed according to a homogenous Poisson point process of intensity λ. Each BS is equipped with M antennas and serves K user equipments. A rigorous stochastic geometry framework with a multi-slope path loss model and pilot-based channel estimation is used to analyze the impact of λ on channel estimation accuracy and spectral efficiency. Both maximum ratio and zeroforcing combiners are considered. Interesting analytical insights are provided into the interplay of network parameters such as λ, antenna-UE ratio M/K, and pilot reuse factor. The relative strength of pilot contamination and (inter-and intracell) interference is analytically and numerically evaluated, as a function of λ. It turns out that pilot contamination becomes relevant only for impractical values of M/K ≥ 100.
This paper is on the spectral efficiency (SE) of a dense multi-cell massive multiple-input multipleoutput (MIMO). The channels are spatially correlated and the multi-slope path loss model is considered.In our framework, the channel state information is obtained by using pilot sequences and the BSs are deployed randomly. First, we study the channel estimation accuracy and its impact on the SE as the BS density increases and the network becomes densified. Second, we consider the special case of uncorrelated channels for which the stochastic geometry framework helps us to simplify the SE expressions, and obtain the minimum value of antenna-UE ratio over which the pilot contamination is dominant rather than the inter-and intra-cell interference. Finally, we provide some insights into the obtained SE for the spatially correlated channels, from a multi-cell processing scheme as well as the single-cell ones in terms of the BS density. Our results show that while all the detectors result in nonincreasing SE in terms of the BS density, their area SE increases exponentially as the network becomes densified. Moreover, we conclude that in order to achieve a given SE, the required value of antenna-UE ratio decreases as the level of channel correlation increases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.