THESIS
2018
xvii, 128 pages : illustrations ; 30 cm
Abstract
The spectral efficiency of small-cell wireless networks is limited by the severe interference
from the neighboring base stations (BSs) as well as the backhaul capacity of the BSs.
In this thesis, we propose a physical layer (PHY) caching scheme to address these two issues.
To address the interference issue, by properly caching some popular contents at the
BSs, the proposed PHY-caching can opportunistically transform the topology of the radio
access network (RAN) from an unfavorable topology (e.g., relay or interference topology)
into a more favorable multiple-input and multiple-output (MIMO) broadcast topology and
enjoy spectrum efficiency gain without large backhaul consumption. To address the backhaul
issue, we consider a joint design of frequency reuse and caching in small-ce...[
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The spectral efficiency of small-cell wireless networks is limited by the severe interference
from the neighboring base stations (BSs) as well as the backhaul capacity of the BSs.
In this thesis, we propose a physical layer (PHY) caching scheme to address these two issues.
To address the interference issue, by properly caching some popular contents at the
BSs, the proposed PHY-caching can opportunistically transform the topology of the radio
access network (RAN) from an unfavorable topology (e.g., relay or interference topology)
into a more favorable multiple-input and multiple-output (MIMO) broadcast topology and
enjoy spectrum efficiency gain without large backhaul consumption. To address the backhaul
issue, we consider a joint design of frequency reuse and caching in small-cell wireless
networks. Spatial caching diversity (i.e., caching different subsets of popular content files at
neighboring BSs) can greatly improve the cache hit probability, thereby leading to a better
overall system performance. A key issue in exploiting spatial caching diversity is that the
cached content may not be located at the nearest BS, which means that to access such content,
a user needs to overcome strong interference from the nearby BSs. Using our proposed
scheme, the benefit of an improved cache hit probability induced by spatial caching diversity
and the benefit of interference coordination induced by frequency reuse can be achieved simultaneously.
Moreover, we further propose an interference-aware dual-mode caching and
user-centric open-loop cooperative transmission scheme that embraces spatial caching diversity
and user-centric open-loop cooperative transmission, and alleviate the interference issue
in the system. For each of the above proposed schemes, we propose corresponding cache
storage capacity allocation algorithms that maximize the spectral efficiency benefits induced
by PHY caching, and quantify the benefits with respect to some important system parameters
such as cache capacity and content popularity distribution. The proposed solution for each
problem is compared with some state-of-the-art baselines, and it is shown through simulations
that significant performance gain can be achieved.
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