Jaesheung Shin

An Efficient Small Data Transmission Scheme in the 3GPP NB-IoT System

This letter proposes an efficient small data transmission scheme in the narrow band (NB)-Internet of Things (IoT) system. For the efficient use of radio resources, the proposed scheme enables devices in an idle state to transmit a small data packet without the radio resource control connection setup process. This can improve the maximum number of supportable devices in the NB-IoT system which has insufficient radio resources. Numerical results have shown that the proposed scheme can increase the maximum number of supportable devices by about 60% compared with the conventional scheme.

A group-based communication scheme based on the location information of MTC devices in cellular networks

Recent standardization efforts in the 3rd Generation Partnership Project (3GPP) have made the Long Term Evolution (LTE) system a very attractive radio access technology for various types of devices and applications. However, the system has not yet been optimized to support diverse traffic profiles. In this paper, we propose a group-based communication scheme to alleviate inefficiencies in the radio access network. The proposed scheme groups multiple connections triggered by different User Equipments (UEs). For the efficient grouping of the UEs, the location information of the Machine-Type Communication (MTC) devices is utilized to identify each group. A four-phase system model is presented to analyze each segment of the connection establishment procedure in the access network. We found that the random access procedure is the main variable factor for the communication delay, and we, therefore, carefully design the procedure with details. Simulations are conducted on our LTE testbeds, and the results show that the proposed scheme is very effective in ensuring the system performance of legacy services and in utilizing radio resources within a given delay bound.

A three-step data transmission scheme for machine type devices in 3GPP LTE systems

This paper proposes a three-step data transmission scheme for massive machine type devices (MTDs) in 3GPP LTE systems. To reduce the signaling overhead for MTDs in idle mode, the proposed scheme adopts a modified random access procedure which enables a MTD to transmit a small-sized data packet once it receives the random access response message. Numerical results have shown that the proposed scheme can increase the maximum number of supportable MTDs by about 30 % compared to the conventional schemes.

Performance Evaluation of Moving Small-Cell Network with Proactive Cache

Due to rapid growth in mobile traffic, mobile network operators (MNOs) are considering the deployment of moving small-cells (mSCs). mSC is a user-centric network which provides voice and data services during mobility. mSC can receive and forward data traffic via wireless backhaul and sidehaul links. In addition, due to the predictive nature of users demand, mSCs can proactively cache the predicted contents in off-peak-traffic periods. Due to these characteristics, MNOs consider mSCs as a cost-efficient solution to not only enhance the system capacity but also provide guaranteed quality of service (QoS) requirements to moving user equipment (UE) in peak-traffic periods. In this paper, we conduct extensive system level simulations to analyze the performance of mSCs with varying cache size and content popularity and their effect on wireless backhaul load. The performance evaluation confirms that the QoS of moving small-cell UE (mSUE) notably improves by using mSCs together with proactive caching. We also show that the effective use of proactive cache significantly reduces the wireless backhaul load and increases the overall network capacity.

Resource allocation for device-to-device communications based on graph-coloring

In device-to-device (D2D) systems, neighboring D2D pairs provide unavoidable interference when a same resource is allocated to multiple D2D pairs. And, this interference acts as a major bottleneck which significantly deteriorates the link quality and prevents from achieving the spatial reuse gain. Hence, in this paper, we introduce the graph-coloring theory and propose a resource allocation algorithm for D2D systems in order to properly avoid dominant interference from neighboring D2D pairs. Throughout simulations results, we show that the proposed scheme provides fairly good performance compared to the optimal resource allocation, while drastically reducing the computational complexity, and performance gain over conventional schemes with respect to sum rate of D2D pairs. Moreover, the results on the outage probability illustrate that the proposed scheme improves the link quality compared to that of conventional schemes.

Performance analysis of small-cell base station with cellular and WiFi RATs

As a multiple radio access technologies (multi-RAT) solution to treat increasing mobile traffic, small-cell base station (SBS) using integration of cellular and WiFi technology has attracted interest from academia, industry, and mobile network operators (MNOs). SBS with multi-RAT can steer their traffic between cellular and WiFi RATs by considering channel condition of each RAT. SBS with multi-RAT has different characteristics based on cellular and WiFi RAT. Performance of SBSs with cellular RAT is mainly affected by signal to interference and noise ratio (SINR) of receiver. This has been analyzed in many research studies by using a point process. However, performance of SBSs with WiFi RAT is rarely analyzed despite the different characteristic of WiFi RAT. In this paper, we introduce the analytical model to estimate performance of WiFi RAT using IEEE 802.11 distributed coordination function (DCF) technique. By using our analytical model, we estimate the number of competing and hidden nodes which mainly influence the performance of WiFi RAT. Results of our analytical model are compared with Monte Carlo simulation, and it is shown that our model can estimate the number of competing and hidden nodes in multi-RAT SBS network.

Dynamic RACH preamble allocation scheme

Machine-to-Machine (M2M) communication is used for automated data transmission and measurement between remote electronic devices. Every device that can use M2M communication will become a significant component of the Internet of Things (IoT) and Big Data. And there are many different applications of M2M communication (e.g., fleet management, smart metering, smart grid, and home/factory/city automation). Machine-Type-Communication (MTC) is a new service defined by the 3GPP to enable M2M devices to communicate with each other over LTE-Advanced cellular networks. Since the number of M2M devices can be fairly large compared to the H2H devices, current RACH procedure may cause a QoS degradation of H2H devices. In this paper, we propose a novel dynamic RACH preamble allocation scheme that can adjust the range of available RACH preamble according to network condition dynamically. The dynamic RACH preamble allocation scheme can be an efficient solution that can alleviate the overload problem.

Performance analysis of MPCs with varying characteristics in different multi-tier HetNet scenarios

One of the most efficient solutions for increasing the spectral efficiency of 5G networks is to deploy hierarchical layering of small low-power and short-range base stations (pico/femto cells) underlying macro base stations. The present state-of-the-art requires these small cells to remain fixed with expensive wired backhauls to the core network. The future cellular networks aim at adopting Moving Personal Cells (MPC) in their multi-tier Heterogeneous Networks (HetNets). MPCs are meant to provide a wireless link between the low-powered base stations and the core network. In this paper, the authors have analyzed the performance of MPCs with varying characteristics in different multi-tier HetNet scenarios. With the help of extensive system-level simulations we conclude that MPCs have great potential to improve the overall network throughput. We have also identified that the access link is the main bottleneck for MPCs underlying HetNet.

Radio resource management for moving small-cells with proactive content cache

The moving small-cell (mSC) is one of solutions to accommodate traffic of the moving users cost-effectively. Due to cache storage in mSC, an mSC can directly send its data for its serving users without any intermediate. In the mSC network, broadcast and multicast protocols are utilized to push the cache contents from macro-cell base station to mSCs by using via wireless backhaul (BH) link. In this paper, we propose the radio resource management scheme for wireless BH link. In the proposed scheme, MBSs select one transmission mode between broadcast and multicast modes based on the popularity distribution of cache contents. By performance evaluation, we confirm that the proposed scheme can adaptively enhance the network performance.

Performance analysis for interference cancellation at the receiver in D2D communication

In this paper, we describe the effect of interference cancellation in the receiver for D2D communication. The relationship between nodes for interference cancellation in the receiver is derived and then the effect of interference cancellation is analyzed from perspectives of the number of nodes, the power consumption, and the sum spectral efficiency. In addition, the range of power control for interference cancellation is described. The analysis shows that interference cancellation in the receiver results in the performance gain from the point of view of the sum spectral efficiency in spite of the power consumption.