82,006 research outputs found
Uplink Performance of Large Optimum-Combining Antenna Arrays in Poisson-Cell Networks
The uplink of a wireless network with base stations distributed according to
a Poisson Point Process (PPP) is analyzed. The base stations are assumed to
have a large number of antennas and use linear minimum-mean-square-error (MMSE)
spatial processing for multiple access. The number of active mobiles per cell
is limited to permit channel estimation using pilot sequences that are
orthogonal in each cell. The cumulative distribution function (CDF) of a
randomly located link in a typical cell of such a system is derived when
accurate channel estimation is available. A simple bound is provided for the
spectral efficiency when channel estimates suffer from pilot contamination. The
results provide insight into the performance of so-called massive
Multiple-Input-Multiple-Output (MIMO) systems in spatially distributed cellular
networks
5G green cellular networks considering power allocation schemes
It is important to assess the effect of transmit power allocation schemes on
the energy consumption on random cellular networks. The energy efficiency of 5G
green cellular networks with average and water-filling power allocation schemes
is studied in this paper. Based on the proposed interference and achievable
rate model, an energy efficiency model is proposed for MIMO random cellular
networks. Furthermore, the energy efficiency with average and water-filling
power allocation schemes are presented, respectively. Numerical results
indicate that the maximum limits of energy efficiency are always there for MIMO
random cellular networks with different intensity ratios of mobile stations
(MSs) to base stations (BSs) and channel conditions. Compared with the average
power allocation scheme, the water-filling scheme is shown to improve the
energy efficiency of MIMO random cellular networks when channel state
information (CSI) is attainable for both transmitters and receivers.Comment: 14 pages, 7 figure
A survey and tutorial of electromagnetic radiation and reduction in mobile communication systems
This paper provides a survey and tutorial of electromagnetic (EM) radiation exposure and reduction in mobile communication systems. EM radiation exposure has received a fair share of interest in the literature; however, this work is one of the first to compile the most interesting results and ideas related to EM exposure in mobile communication systems and present possible ways of reducing it. We provide a comprehensive survey of existing literature and also offer a tutorial on the dosimetry, metrics, international projects as well as guidelines and limits on the exposure from EM radiation in mobile communication systems. Based on this survey and given that EM radiation exposure is closely linked with specific absorption rate (SAR) and transmit power usage, we propose possible techniques for reducing EM radiation exposure in mobile communication systems by exploring known concepts related to SAR and transmit power reduction in mobile systems. Thus, this paper serves as an introductory guide to EM radiation exposure in mobile communication systems and provides insights toward the design of future low-EM exposure mobile communication networks
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