• Journal of Broadcast Engineering
• /
• v.21 no.3
• /
• pp.404-411
• /
• 2016

In this paper, we investigate the radio wave radiation pattern to measure the actual field strength for the transmission antenna dipole antenna and the CP-ring antenna being used in our country as FM station, and the comparison was for field application. Compare results, If the transmitting station and the relay station which is located in the middle of a service area has been a useful CP-dipole antenna (four directions). CP-ring antenna having a directivity because the reflection effect of the tower was able to adjust the orientation to prevent the spread of menstrual another service area in the main direction was able to radiate high propagation 5~9dB. Especially, If the transmitting station and the relay station is located on one side of the service area for radiating radio waves in three directions by using the CP-ring antennas focus the orientation of the antenna in populated areas and road area can improve the broadcast reception environment.

• Proceedings of the IEEK Conference
• /
• 2002.07c
• /
• pp.1447-1450
• /
• 2002

In this paper, we propose a new access method named UR (Use. Relay) scheme to improve the channel efficiency in mobile communications. In UR scheme, packets of a data terminal that do not demand real time communications are relayed by other terminals during their inactive periods, which ue communicating with the base station through a fixed channel at that time. Simulation results show that with UR scheme, the blocking probability md the throughput are improved considerably with an allowable increase in the average delay.

• Journal of the Korea Society for Simulation
• /
• v.14 no.3
• /
• pp.33-42
• /
• 2005

One of the imminent problems to be solved within wireless sensor network is to balance out energy dissipation among deployed sensor nodes. In this paper, we present a transmission relay method of communications between BS (Base Station) and CHs (Cluster Heads) for balancing the energy consumption and extending the average lifetime of sensor nodes by the fuzzy logic application. The proposed method is designed based on LEACH protocol. The area deployed by sensor nodes is divided into two groups based on distance from BS to the nodes. RCH (Relay Cluster Head) relays transmissions from CH to BS if the CH is in the area far away from BS in order to reduce the energy consumption. RCH decides whether to relay the transmissions based on the threshold distance value that is obtained as a output of fuzzy logic system, Our simulation result shows that the application of fuzzy logic provides the better balancing of energy depletion and prolonged lifetime of the nodes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2019.05a
• /
• pp.286-287
• /
• 2019

In this paper, we consider an amplify-and-forward (AF) full duplex (FD) massive-antenna relay (or base station) aiding communication between K single-antenna source and destination pairs whose transmissions are overheard by one single-antenna eavesdropper. Maximum ratio combining (MRC) and maximum ratio transmission (MRT) processing is employed at the relay. The secrecy performance of the system is then derived with both relay and destination being equipped with low resolution analog-to-digital converters (ADCs). The results show the detrimental effect of the eavesdropper's presence on the sum rate of the system.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.1
• /
• pp.365-382
• /
• 2021

This paper proposes a novel two-way relaying (TWR) approach for a two-relay wireless network based on non-orthogonal multiple access (NOMA), where two terminals exchange messages with a cellular base station (BS) via two intermediate relay stations (RSs). We propose a NOMA-based TWR approach with two relaying schemes, i.e., amplify-and-forward (AF) and decode-and-forward (DF), referred to as NOMA-AF and NOMA-DF. The sum-rate performance of our proposed NOMA-AF and NOMA-DF is analyzed. A closed-form sum-rate upper bound for the NOMA-AF is obtained, and the exact ergodic sum-rate of NOMA-DF is also derived. The asymptotic sum-rate of NOMA-AF and NOMA-DF is also analyzed. Simulation results show that the proposed scheme outperforms conventional orthogonal multiple access based transmission schemes. It is also shown that increasing the transmit power budget of the relays only cannot always improve the sum-rates.

• Journal of Advanced Navigation Technology
• /
• v.12 no.6
• /
• pp.598-603
• /
• 2008

Relay system is a promising technique for the high downlink throughput or coverage extension in the next generation wireless systems. In this paper, the transmit scheme for orthogonal frequency division multiplexing (OFDM) based relay system with hierarchical modulation is designed. Without using much power from the base station, the proposed scheme can guarantee the cell edge users to get high data rates as the inner cell users. In the simulation, the performance of proposed scheme was compared with the conventional one in which there is no hierarchical modulation. Numerical results show that the proposed scheme can save much power whether the unicast case or multicast case.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.6 no.9
• /
• pp.2098-2117
• /
• 2012

This paper jointly investigates the bandwidth allocation, transmission strategy and relay positions for two-way transmission aware cellular networks with network coding (NC). Our goal is to minimize the transmission power of mobile terminals (MTs). Consider a cellular system, where multiple MTs exchange information with their common base station, firstly, we propose an efficient bandwidth allocation method and then give a transmission strategy for each MT to determine whether to use relay stations (RSs) for its two-way transmission with the BS or not. To further improve the system performance, the optimal positions of RSs are also jointly discussed. A GA-based algorithm is presented to obtain the optimum positions for RSs. Besides, the impacts of frequency reuse on MT's transmission power and system spectral efficiency (SE) under different number of relays are also discussed in our work. Numerical results show that the proposed NC aware scheme can extend MTs' battery life at least 6% more than traditional method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.8 no.6
• /
• pp.656-664
• /
• 1997

This paper introduces a fixed radio-relay link design simulator with which we can select the station site and the frequency and can predict the performance of the radio-relay links. The simulator analyzes the path profile, the fading effects, the availability, the rain attenuation and the interference of the cosidered radio path using the digital terrain data and the rain intensity data. The calculation algorithms used in this simulator are mostly from the recommendations of the ITU-R. All the modules of the simulator are performed in full GUI mode and the input and output parameters are displayed interactively. This simulator could be used to the fixed radio-relay link design and the LMDS design.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.2B
• /
• pp.170-177
• /
• 2009

In this paper, we propose the structures of the NBTC (Narrow-Beam Trisector Cell) and the WBTC(Wide-Beam Trisector Cell) in which directional antennas both at the base station and at the relay station are used. We analyze and compare total capacity of the both systems taking the co-channel interference into consideration for two channel models. Through analysis, we find the effect of LOS (Lind of Sight) path to the total capacity of NBTC structure and that of WBTC structure. Our work may be useful as a guideline to control the interference for the next generation mobile communication and WiBro systems using multi-hop relays.

• Journal of Broadcast Engineering
• /
• v.15 no.2
• /
• pp.157-162
• /
• 2010

In this paper, We propose that the adaptive cooperative relay transmission technique using closed-loop MIMO scheme for duplex communication system. As the mobility between relay and base station is little, closed-loop MIMO is better diversity gain than open-loop MIMO. At this time, more than one relaying terminals are included in one cooperative group to share their transmission and take precoding weight feedback. For minimization of throughput reduction caused by increasing feedback bits, we use codebook-based MRT that limit the number of feedback bits. Among the cooperative relay group, the best relays are selected from the base stataion and get the feedback. A protocol senarios are also proposed for this relay system.