Practical large scale antenna systems for 5G cellular communications

In order to increase capacity and reduce power consumption for future cellular networks, new cellular architectures and radio access schemes will be required. Two important technologies for future 5G networks include Cloud-Radio Access Networks (C-RAN) [1] and Large Scale Antenna Systems (LSAS) with hundred's of low power radios to increase the cell capacity with multi-user MIMO multiplexing and beamforming. Although LSAS in theory [2] promises large capacity gains at the fraction of the power consumed by the current macro-basestations; there are many practical challenges that need to be overcome before LSAS can be successfully integrated into current and future cellular networks including: 1) low-power beamforming algorithms and 2) irregular array beamforming. This project examines each challenge and proposes possible solutions

User Detection Performance Analysis for Grant-Free Uplink Transmission in Large-Scale Antenna Systems

In this paper, user detection performance of a grant-free uplink transmission in a large scale antenna system is analyzed, in which a general grant-free multiple access is considered as the system model and Zadoff-Chu sequence is used for the uplink pilot. The false alarm probabilities of various user detection schemes under the target detection probabilities are evaluated

Dominant Channel Estimation via MIPS for Large-Scale Antenna Systems with One-Bit ADCs

In large-scale antenna systems, using one-bit analog-to-digital converters (ADCs) has recently become important since they offer significant reductions in both power and cost. However, in contrast to high-resolution ADCs, the coarse quantization of one-bit ADCs results in an irreversible loss of information. In the context of channel estimation, studies have been developed extensively to combat the performance loss incurred by one-bit ADCs. Furthermore, in the field of array signal processing, direction-of-arrival (DOA) estimation combined with one-bit ADCs has gained growing interests recently to minimize the estimation error. In this paper, a channel estimator is proposed for one-bit ADCs where the channels are characterized by their angular geometries, e.g., uniform linear arrays (ULAs). The goal is to estimate the dominant channel among multiple paths. The proposed channel estimator first finds the DOA estimate using the maximum inner product search (MIPS). Then, the channel fading coefficient is estimated using the concavity of the log-likelihood function. The limit inherent in one-bit ADCs is also investigated, which results from the loss of magnitude information.Comment: to appear in GLOBECOM 2018, Abu Dhabi, UA

Efficient large scale antenna selection by partial switching connectivity

In this work we analyze the benefits of low-complexity radio frequency (RF) switching matrices (SMs) for antenna selection (AS) in large scale antenna systems (LSAS). The reduced RF complexity and insertion losses (ILs) are attained by limiting the number of internal connections in the SM, at the expense of a limited flexibility in the AS. The results presented in this paper demonstrate that partially-connected (PC) SMs outperform conventional fully-flexible (FF) alternatives due to their reduced ILs, which are characterized in this work