• Journal of Advanced Navigation Technology
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• v.16 no.1
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• pp.96-102
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• 2012

The goal of mobile internet system is to provide a high-data-rate, low-latency and optimized packet radio access technology supporting flexible bandwidth deployments. Therefore, network architecture is designed with the goal to support packet-switched traffic with seamless mobility, quality of service and minimal latency. An important requirement for the mobile internet system is improved cell-edge BER performance and data throughput. This is to provide some level of service consistency in terms of geographical coverage as well as in terms of available data throughput within the communication coverage area. In a cellular system, however, the signal to interference plus noise power ratio gap between cell-center and cell-edge users can be of the order of 20 [dB]. The disparity can be even higher in a communication coverage limited cellular system. This leads to vastly lower data throughputs for the cell-edge users relative to cell-center users creating a large QoS gap. This paper proposes a analytical approach that tries to reduce inter-cell interference, and shows the SIR and BER performance according to the OFDM system parameters in mobile Internet environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37A no.10
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• pp.885-894
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• 2012

Currently, Demand of data traffic has rapidly increased by popular of smart device. It is very difficult to accommodate demand of data traffic by limited resource of base station (BS). To solve this problem, method has proposed that the Device-to-Device (D2D) reduce frequency overload of the BS and all of the user equipment (UE) inside the BS and neighbor BS don't allow communicating directly to BS. However, in LTE-Advance system cellular link and sharing radio resources of D2D link, the strong interference of the cellular network is still high. So we need to eliminate or mitigate the interference. In this paper, we use the transmission power control method and Soft Frequency Reuse (SFR) resource allocation method to mitigate the interference of the cellular link and D2D link. Simulation results show that the proposed scheme has high performance in terms of Signal to Noise Ratio (SINR) and system average throughput.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.43-51
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• 2015

Upcoming cellular networks such as LTE-advanced and IEEE 802.16m are enhanced by relay stations to support high data rate multimedia services and minimize the shadow zone with low cost. Enhancing the relay stations, however, divides the multihop cellular network into smaller microcells and the distance between microcells is closer, which intends large intra-cell and inter-cell interference. Especially the access link on downlink in the OFDMA cellular network is the throughput bottleneck due to the severe interference caused by base stations and relay stations transmitting large data to mobile stations simultaneously. In this paper, we present interference aware channel allocation algorithm to avoid severe interference on multihop cellular networks with random topology. Proposed algorithm increases SINR(signal to interference plus noise ratio) and decreases number of required control messages for channel allocation, so that increases overall throughput on the networks.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2019.05a
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• pp.392-394
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• 2019

Tunnels and subterranean roads, which are representative evacuation facilities for national or regional disasters, have radio relay broadcasting facilities for legal reasons and convenience reasons. However, this system is limited to radio broadcasting and it is impossible to effectively communicate disaster or emergency situations that occur locally due to broadcasting of national broadcasting without DMB broadcasting. In order to improve this, we construct a remote disaster broadcasting system at each regional disaster station and implement a system to transmit it to each tunnel using internet or LTE network. The system in the tunnel transmits the emergency broadcasting signal through the existing relay equipment through the modulator which decodes the SMS, the media file, the real time broadcasting or the image received by the digital signal and converts it into FM and DMB frequency. The method proposed and implemented in this study can be used to provide efficient information and remote field control in case of emergency in tunnel and underground roadway.

• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.71-76
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• 2015

In this paper, we propose a system model which effectively transmits the data and conducts RF energy harvesting in a wireless communication network of LTE and 5G. Through time switching and power splitting schemes, we find a time & power ratio to show the good performance according to the standard that we set up for transmitting a signal and conducting RF energy harvesting. So selecting optimal time & power ratio, we can efficiently transfer data to other drones and harvest the amount of harvested power simultaneously we desire. Also, according to conducting the performance analysis, we can compare an ideal receiver with the proposed system model. And, we suggest a future direction of research.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.7
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• pp.389-397
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• 2014

This paper focuses on advanced receiver for interference suppression or cancellation from neighbor cells in the 3GPP Rel-12 standard. From UE (User Equipment) perspective, the advanced receiver which can manage inter-cell interference of adjacent cell is required to support and manage fast-growing wireless data traffic. In 3GPP standard, NAICS which is one of approaches to improve SINR and receiver performance by directly suppression or cancellation of data (PDSCH) and control (PDCCH) signal from interference cells is discussed. In this paper, we briefly introduce the concept and candidate receivers for NAICS (Network Assisted Interference Cancellation and Suppression) based on 3GPP Rel-12 standard, and simulation results for basic NAICS receiver performance are provided.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.2
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• pp.32-38
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• 2012

In this paper, we design on nonliner 3 user Dirty Paper Precoding for MIMO adjacant interference signal cancellation based on 3 GPP LTE Release 10. In this paper, in order to reduce the inter-channel interference at the transmitted side, we propose the Dirty Paper Precoding scheme for 3-user MIMO wireless systems using LQ decomposition and Gram-Schmidt algorithm based in its orthonormal basis.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.4
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• pp.31-40
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• 2019

This paper proposes an adaptive PCIe system for TI C66x DSPs. Conventionally, the PCIe system provided by the C66x is a system dependent on the structure in which the primary core writes an application to the DSP memory through the PCIe interface, then activate the secondary core. Due to the dependency between the cores, when developing a project using a PCIe interface, the remaining cores have to be programmed with a concern of the primary core used as the PCIe interface. Therefore, in order to de-couple the connections among the cores, an adaptive PCIe system is proposed, in the paper, in which the cores operate independently compared to the conventional system. Since the core used as the PCIe interface only runs PCIe related operations in the new system, the remaining cores can be fully utilized without concerning the connections with the core for PCIe interface. In order to verify the feasibility of the proposed adaptive PCIe system, the implementations of LTE-A down link, and IEEE 802.11ac are carried out using the evaluation board which includes a TMS320C6670 chip. Altogether, these results support that we demonstrated that the digital signal processing systems with the PCIe Interface can be developed more rapidly by applying the proposed system.

• ETRI Journal
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• v.40 no.1
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• pp.51-60
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• 2018

In Long Term Evolution (LTE) cellular networks, the transmit power control (TPC) mechanism consists of two parts: the open loop (OL) and closed loop. Most cellular networks consider OL/TPC because of its simple implementation and low operation cost. The analysis of OL/TPC parameters is essential for efficient resource management from the cellular operator's viewpoint. In this work, the impact of the OL/TPC parameters is investigated for homogeneous small cells and heterogeneous small-cell/macrocell network environments. A mathematical model is derived to compute the transmit power at the user equipment, the received power at the eNodeB, the interference in the network, and the received signal-to-interference ratio. Using the analytical platform, the effects of the OL/TPC parameters on the system performance in LTE networks are investigated. Numerical results show that, in order to achieve the best performance, it is appropriate to choose ${\alpha}_{small}=1$ and $P_{o-small}=-100dBm$ in a homogenous small-cell network. Further, the selections of ${\alpha}_{small}=1$ and $P_{o-small}=-100dBm$ in the small cells and ${\alpha}_{macro}=0.8$ and $P_{o-macro}=-100dBm$ in the macrocells seem to be suitable for heterogeneous network deployment.

• Journal of Communications and Networks
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• v.18 no.2
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• pp.150-161
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• 2016

Coordinated multi-point transmission (CoMP) techniques are being touted as enabling technologies for interference mitigation in next generation heterogeneous wireless networks (HetNets). In this paper, we present a comparative performance study of uplink (UL) CoMP algorithms for the 3GPP LTE HetNets. Focusing on a distributed and functionally-split architecture, we consider six distinct UL-CoMP algorithms: 1. Joint reception in the frequency-domain (JRFD) 2. Two-stage equalization (TSEQ) 3. Log-likelihood ratio exchange (LLR-E) 4. Symmetric TSEQ (S-TSEQ) 5. Transport block selection diversity (TBSD) 6. Coordinated scheduling with adaptive interference mitigation (CS-AIM) where JRFD, TSEQ, S-TSEQ, TBSD and CS-AIM are our main contributions in this paper, and quantify their relative performances via the post-processing signal-to-interference-plus-noise ratio distributions.We also compare the CoMP-specific front-haul rate requirements for all the schemes considered in this paper. Our results indicate that, with a linear minimum mean-square error receiver, the JRFD and TSEQ have identical performances, whereas S-TSEQ relaxes the front-haul latency requirements while approaching the performance of TSEQ. Furthermore, in a HetNet environment, we find that CS-AIM provides an attractive alternative to TBSD and LLR-E with a significantly reduced CoMP-specific front-haul rate requirement.