• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5C
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• pp.355-363
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• 2005

This paper is discussed about the technology of the performance enhancement in the wireless communication between indoor and outdoor environments. In the outdoor wireless communication, the signal has mainly a severe degradation by the fading effect of channel, but that problem may be overcome by using ordinary multiple antenna technology and array signal processing algorithm. Hence, since the channel has the characteristics of both fading and angle spread in the wireless communication between indoor and outdoor, the ordinary technology cannot solve the signal degradation due to the angle spread. In order to solve the problem, in this paper, the characteristic of the wireless channel between indoor and outdoor is first analyzed and considered the channel models fit to that case. We propose the new multiple antenna algorithm by use of mean steering vector concept, and obtained the results of the performance enhancement. With the results of the performance analyses through of the numerical study and computer simulation, we show that the proposed algorithm has more enhanced signal to noise ratio than the previous algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.10
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• pp.3858-3874
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• 2021

As an essential part of the urban transportation system, precise perception of the traffic flow parameters at the traffic signal intersection ensures traffic safety and fully improves the intersection's capacity. Traditional detection methods of road traffic flow parameter can be divided into the micro and the macro. The microscopic detection methods include geomagnetic induction coil technology, aerial detection technology based on the unmanned aerial vehicles (UAV) and camera video detection technology based on the fixed scene. The macroscopic detection methods include floating car data analysis technology. All the above methods have their advantages and disadvantages. Recently, indoor location methods based on wireless signals have attracted wide attention due to their applicability and low cost. This paper extends the wireless signal indoor location method to the outdoor intersection scene for traffic flow parameter estimation. In this paper, the detection scene is constructed at the intersection based on the received signal strength indication (RSSI) ranging technology extracted from the wireless signal. We extracted the RSSI data from the wireless signals sent to the road side unit (RSU) by the vehicle nodes, calibrated the RSSI ranging model, and finally obtained the traffic flow parameters of the intersection entrance road. We measured the average speed of traffic flow through multiple simulation experiments, the trajectory of traffic flow, and the spatiotemporal map at a single intersection inlet. Finally, we obtained the queue length of the inlet lane at the intersection. The simulation results of the experiment show that the RSSI ranging positioning method based on wireless signals can accurately estimate the traffic flow parameters at the intersection, which also provides a foundation for accurately estimating the traffic flow state in the future era of the Internet of Vehicles.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.109-116
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• 2014

In recent, ISM (Industrial Scientific Medical) band that is 2.4GHz band authorized free of charge is being widely used for smart phone, notebook computer, printer and portable multimedia devices. Accordingly, studies have been continuously conducted on the possibility of coexistence among nodes using ISM band. In particular, the interference of IEEE 802.11b based Wi-Fi device using overlapping channel during communication among IEEE 802.15.4 based wireless sensor nodes suitable for low-power, low-speed communication using ISM band causes serious network performance deterioration of wireless sensor networks. This paper examined a method of identifying channel status to avoid interference among wireless communication devices using IEEE 802.11b (Wi-Fi) and other ISM bands during communication among IEEE 802.15.4 based wireless sensor network nodes in ISM band. To identify channels occupied by Wi-Fi traffic, various studies are being conducted that use the RSSI (Received Signal Strength Indicator) value of interference signal obtained through ED (Energy Detection) feature that is one of IEEE 802.15.4 transmitter characteristics. This paper examines an algorithm that identifies the possibility of using more accurate channel by mixing utilization of interference signal and RSSI mean value of interference signal by wireless sensor network nodes. In addition, it verifies such algorithm by using OPNET Network verification simulator.

• Journal of electromagnetic engineering and science
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• v.12 no.1
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• pp.77-84
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• 2012

This paper introduces our development of a MIMO-OTA system with simplified configuration. The key element of our proposal is the adoption of an antenna branch-controlled configuration for generating multipath delayed waves. The signal processing is carried out on IF band signal with an FPGA in a fading-emulator-type MIMO-OTA measurement system. The proposed scheme is largely different from available system configurations for the fading simulator method of constructing the OTA test environment. We describe the principle of the proposed scheme, channel model incorporated in the system, basic configuration of the developed system, and its performance.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.4
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• pp.1041-1062
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• 2012

In this paper, we propose a hybrid cooperative scheme to improve the secrecy rate for a cooperative network in presence of multiple relays. Each relay node transmits the mixed signal consisting of weighted source signal and intentional noise. The problem of power allocation, the joint design of beamforming and jamming weights are investigated, and an iterative scheme is proposed. It is demonstrated by the numerical results that the proposed hybrid scheme further improves secrecy rate, as compared to traditional cooperative schemes.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.3
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• pp.75-81
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• 2017

This paper estimate a desired signal in a correlation wireless communication. The transmitted signal is mixed with the information signal, interference, and noise in wireless channel, and it is incident on the receiver. In this paper, we apply MUSIC algorithm and sub-array method to recover the total rank of the correlation matrix in order to estimation a desired signal among receiving signals. Through simulation, we analyze to compare the proposed method with the classical MUSIC algorithm. As a result of the simulation, the proposed method improved the resolution about 10degrees compared to the conventional MUSIC algorithm. We prove the superiority of the proposed method for the desired signal estimation in correlation channel.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.3
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• pp.253-262
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• 2003

In this paper, the interference cancellation system, which is used to cancel the feedback signal in the wireless communication system with the same frequency, is studied. The time varying feedback signal generated from transmitter antenna to receiver antenna reduces the performance of the receiver system. the interference cancellation system using adaptive feedback method(AF-ICS) is suggested to prevent the oscillation of the receiver system and maintain the maximum output power of the power amplifier by the reduction of time-varying feedback signal and also this paper conforms that the oscillation disappears from the output signal by cancellation of the feedback signal and the total output power is satisfied the system specification.

• Korean Journal of Agricultural Science
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• v.38 no.4
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• pp.747-752
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• 2011

Wireless technology has enabled farmers monitor and control protected production environment more efficiently. Utilization of USN (Ubiquitous Sensor Network) devices also brought benefits due to reduced wiring and central data handling requirements. However, wireless communication loses signal under unfavorable conditions (e.g., blocked signal path, low signal intensity). In this paper, performance of commercial wireless communication devices were evaluated for application to protected crop production. Two different models of wireless communication devices were tested. Sensors used in the study were weather units installed outside and top of a greenhouse (wind velocity and direction, precipitation, temperature and humidity), inside ambient condition units (temperature, humidity, $CO_2$, and light intensity), and irrigation status units (irrigation flow and pressure, and soil water content). Performance of wireless communication was evaluated with and without crop. For a 2.4 GHz device, communication distance was decreased by about 10% when crops were present between the transmitting and receiving antennas installed on the ground, and the best performance was obtained when the antennas were installed 2 m above the crop canopy. When tested in a greenhouse, center of a greenhouse was chosen as the location of receiving antenna. The results would provide information useful for implementation of wireless environment monitoring system for protected crop production using USN devices.

• International Journal of Advanced Culture Technology
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• v.9 no.4
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• pp.409-416
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• 2021

We are invented the movement composition technique that is to check the food adjacent-package status of the wireless-management movement monitoring level (WMMML) on the movement monitoring communication system. The movement monitoring level condition by the movement monitoring communication system is formatted with the adjacent-package system. As to inspection a wireless RFID of the wireless RFID, we are found of the movement value with wireless RFID by the adjacent upper take form. The concept of movement monitoring level is formatted the reference of wireless-management level for composition signal by the movement package communication system. Further symbolizing a food composition of the WMMML of the medium-minimum in terms of the adjacent-package communication system, and the movement wireless RFID package that was the movement value of the far composition of the Mo-MMCS-FA-_φMED-MIN with 5.80±1.20 units, that was the movement value of the convenient composition of the Mo-MMCS-CO-_φMED-MIN with 4.06±(-0.04) units, that was the movement value of the flank composition of the Mo-MMCS-MO-_φMED-MIN with 0.91±0.07 units, that was the movement value of the vicinage composition of the Mo-MMCS-VI-_φMED-MIN with 0.18±(-0.03) units. The adjacent package will be to look into at the food ability of the adjacent-package communication system with wireless RFID by the movement monitoring level on the WMMML that is supply the wireless communication by the movement monitoring level system. We will be possible to make effort of a communication system by the management signal and to put to use of the delivery data of RFID level by the delivery system.

• Journal of Digital Contents Society
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• v.14 no.3
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• pp.349-356
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• 2013

Products of Wi-Fi devices in recent years offer higher throughput and have longer signal coverage which also bring unnecessary signal interference to neighboring wireless networks, and result in decrease of network throughput. Signal interference is an inevitable problem because of the broadcast nature of wireless transmissions. However it could be optimized by reducing signal coverage of wireless devices. On the other hand, smaller signal coverage also means lower transmission power and lower data throughput. Therefore, in this paper, we analyze the relationship among signal strength, coverage and interference of Wi-Fi networks, and as a tradeoff between transmission power and data throughput, we propose a range-aware Wi-Fi network scheme which controls transmission power according to positions and RSSI(Received Signal Strength Indication) of Wi-Fi devices and analyze the efficiency of the proposed scheme by simulation.