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.

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This paper proposes a new time division multiple access (TDMA) based multi-hop resource(slots) reservation protocol (TMRR) for tactical mobile adhoc networks (T-MANET). TMRR lets a node reserve the channel resource for multi-hop packet transmission in consecutive order, so that the packet transmission between a source node and a multi-hop away destination node is possible within a superframe. This paper evaluates the performance of the proposed protocol via OPNET simulation in terms of the average end-to-end delay and the average throughput in both static and mobile environments. And this paper compares it to that of the Evolutionary-TDMA (E-TDMA) which is a representative reservation-based medium access control (MAC) protocol considering node mobility in MANET. According to the simulation results of the single-hop scenarios, TMRR gives better packet throughput and delay performance than E-TDMA as the offered traffic is increased. For the multi-hop scenarios, the average end-to-end delay of TMRR nodes meets the multi-hop end-to-end delay requirements because a node can transmit the packets to a multi-hop away node within a superframe.

Korean military is developing the next generation military satellite communications system in order to achieve the requirements of future military satellite communication such as high speed, high capacity, survivability, all IP networking, and on-the-move. In this paper, we survey and analyze the research interests about optimal resource allocation and IP networking such as MF-TDMA, random access, satellite IP routing, and PEP. Conventional researches have focused on the increase in channel throughput and efficiency. In addition to these measurements, we consider heterogeneous satellite terminals, full mesh topology, distributed network, anti-jamming, and the like which are the special characteristics of the next generation military satellite communications system. Based on this, we present key research issues and evaluation on the issues by simulation.