Abstract
In millimeter wave (mmWave) communication systems, beamforming-enabled directional transmission and network densification are usually used to overcome severe signal path loss problem and improve signal coverage quality. The combination of directional transmission and network densification poses a challenge to radio access resource management. The existing work presented an effective solution for dense mmWave wireless local area networks (WLANs). However, this scheme cannot adapt to network expansion when it is applied directly to dense mmWave cellular networks. In addition, there is still room for improvement in terms of energy efficiency and throughput. Therefore, we firstly propose an efficient hierarchical beamforming training (BFT) mechanism to establish directional links, which allows all the small cell base stations (SBSs) to participate in the merging of training frames to adapt to network expansion. Then, we design a BFT information-aided radio access resource allocation algorithm to improve the downlink energy efficiency of the entire mmWave cellular network by reasonably selecting beam directions and optimizing transmission powers and beam widths. Simulation results show that the proposed hierarchical BFT mechanism has the smaller overhead of BFT than the existing BFT mechanism, and the proposed BFT information-aided radio access resource allocation algorithm outperforms the existing corresponding algorithm in terms of average energy efficiency and throughput per link.
Highlights
The growing popularity of the mobile Internet and the Internet of things [1,2,3] as well as the increasing perceptual services [4,5,6] has led to a continued high demand for network capacity, in which more spectrum is needed to support [7]
Unlike the above studies that focus on the sum data rate improvement of the entire millimeter wave (mmWave) wireless local area networks (WLANs) by proper mmWave beam allocation, we focus on the energy efficiency improvement of the entire mmWave cellular network, since the energy consumption problem becomes more prominent in high-capacity network applications
This is because the difference in the number and location distribution of user equipment (UE) leads to the random variation of mutual interference
Summary
The growing popularity of the mobile Internet and the Internet of things [1,2,3] as well as the increasing perceptual services [4,5,6] has led to a continued high demand for network capacity, in which more spectrum is needed to support [7]. The combination of directional transmission and network densification will create new difficulties for radio access resource management, where improper mmWave beam allocation will lead to nonnegligible interferences between communication nodes. In order to reduce the overhead of beamforming training (BFT) in a dense mmWave cellular network, inspired by the BFT mechanism in [19], we propose an efficient hierarchical BFT mechanism to establish directional links. We model the radio access resource management for downlink communication in the dense mmWave cellular network as an optimization problem and design a hierarchical BFT informationaided radio access resource allocation algorithm to improve the downlink energy efficiency of the entire mmWave cellular network by reasonably selecting beam directions and optimizing transmission powers and beam widths.
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