19,054 research outputs found
Ultra-Dense Networks: Is There a Limit to Spatial Spectrum Reuse?
The aggressive spatial spectrum reuse (SSR) by network densification using
smaller cells has successfully driven the wireless communication industry
onward in the past decades. In our future journey toward ultra-dense networks
(UDNs), a fundamental question needs to be answered. Is there a limit to SSR?
In other words, when we deploy thousands or millions of small cell base
stations (BSs) per square kilometer, is activating all BSs on the same
time/frequency resource the best strategy? In this paper, we present
theoretical analyses to answer such question. In particular, we find that both
the signal and interference powers become bounded in practical UDNs with a
non-zero BS-to-UE antenna height difference and a finite UE density, which
leads to a constant capacity scaling law. As a result, there exists an optimal
SSR density that can maximize the network capacity. Hence, the limit to SSR
should be considered in the operation of future UDNs.Comment: conference submission in Oct. 201
On the Performance of Multi-tier Heterogeneous Cellular Networks with Idle Mode Capability
This paper studies the impact of the base station (BS) idle mode capability
(IMC) on the network performance of multi-tier and dense heterogeneous cellular
networks (HCNs). Different from most existing works that investigated network
scenarios with an infinite number of user equipments (UEs), we consider a more
practical setup with a finite number of UEs in our analysis. More specifically,
we derive the probability of which BS tier a typical UE should associate to and
the expression of the activated BS density in each tier. Based on such results,
analytical expressions for the coverage probability and the area spectral
efficiency (ASE) in each tier are also obtained. The impact of the IMC on the
performance of all BS tiers is shown to be significant. In particular, there
will be a surplus of BSs when the BS density in each tier exceeds the UE
density, and the overall coverage probability as well as the ASE continuously
increase when the BS IMC is applied. Such finding is distinctively different
from that in existing work. Thus, our result sheds new light on the design and
deployment of the future 5G HCNs.Comment: conference submissio
Wireless Powered Dense Cellular Networks: How Many Small Cells Do We Need?
This paper focuses on wireless powered 5G dense cellular networks, where base
station (BS) delivers energy to user equipment (UE) via the microwave radiation
in sub-6 GHz or millimeter wave (mmWave) frequency, and UE uses the harvested
energy for uplink information transmission. By addressing the impacts of
employing different number of antennas and bandwidths at lower and higher
frequencies, we evaluate the amount of harvested energy and throughput in such
networks. Based on the derived results, we obtain the required small cell
density to achieve an expected level of harvested energy or throughput. Also,
we obtain that when the ratio of the number of sub-6 GHz BSs to that of the
mmWave BSs is lower than a given threshold, UE harvests more energy from a
mmWave BS than a sub-6 GHz BS. We find how many mmWave small cells are needed
to perform better than the sub-6 GHz small cells from the perspectives of
harvested energy and throughput. Our results reveal that the amount of
harvested energy from the mmWave tier can be comparable to the sub-6 GHz
counterpart in the dense scenarios. For the same tier scale, mmWave tier can
achieve higher throughput. Furthermore, the throughput gap between different
mmWave frequencies increases with the mmWave BS density.Comment: pages 1-14, accepted by IEEE Journal on Selected Areas in
Communication
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