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The use of a millimeter-wave band defined as a 30–300 GHz range is significant element for improving performance of 5th generation (5G) mobile communication systems. However, since the millimeter-wave signal has peculiar propagation characteristics especially toward non-line-of-sight regions, the system architecture and antenna structure for 5G mobile communications should be designed to overcome these propagation limitations. For realization of the 5G mobile communications, electronics and telecommunications research institute (ETRI) is developing central network applying various massive antenna structures with beamforming. In this paper, we have introduced the central network and evaluated the system coverage and capacity through C++ language-based simulations with real geospatial information.

Heterogeneous network (HetNet) is an opportunistic technology that improves network throughput, extends cell coverage, and offloads the network traffic for 5G mobile communication network. HetNet involves a mix of radio technologies and various cell types working together seamlessly. In a HetNet, the coordination between macro cells (MCs) and small cells (SCs) has a positive impact onthe performance of the overall networks, and consequently on the overall user experience. Therefore, the improvement of user-perceived service quality requires high-efficiency network protocol as well as enhanced radio technologies. In this article, we introduce a 5G HetNet comprised of MCs, fixed and mobile SCs. Mobile small cells (mSCs) can be mounted on a car, bus, and train. They have different aspect from the fixed small cells (fSCs), and hence we address the technical challenges for mSCs in this article. We also analyze the network performance under two HetNet scenarios, such as MCs and fSCs, and MCs and mSCs.

This letter proposes an enhanced inter-beam handover (IBH) scheme for millimeter-wave mobile communication systems. The proposed scheme adopts an inter-beam coordinated scheduling to improve the performance of the IBH which can be seriously deteriorated. In addition, the proposed scheme exploits the small-sized low layer messages to reduce the signaling overhead for the IBH by considering the main features of the IBH. Numerical results have shown that the proposed scheme can decrease the handover failure rate and reduce the signaling overhead by 78%∼92% compared with the conventional scheme.Index Terms-Inter-beam handover, coordinated scheduling, mmWave frequency band, handover performance.