• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.6
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• pp.671-676
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• 2015

Cooperative networks eliminate shadow area using relay and enhance communication performance by creating virtual multi input multi output (MIMO) system. In this paper, we analyze the performance of cooperative networks which use coherent modulation scheme in source-relay nodes and differential modulation scheme in relay-destination nodes depending on the relay location. We consider the performance analysis of systems with and without the direct transmission between source and destination node where the direct transmission adopts differential modulation scheme. In addition, the performance of the system with fully differential modulation scheme is compared with the system using partially differential modulation scheme. The performance of system is based on the symbol error rate between source and destination node.

• Journal of IKEEE
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• v.13 no.4
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• pp.75-81
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• 2009

The cellular system in the next generation decreases the range of transmission of a signal as well as increases the rate of transmission adapting the method of multi-hop relaying with the relay. However, the fact of decreasing the range of transmission with the method of multi-hop relaying means increasing interferential amount in the outer cell; therefore, the deployment of the relay can affect to the function of the cellular system. In this thesis, the deployment of the relay is determined for the maximum rate of transmission, based on the transmission power of the relay and the variation of interferential amount. The condition to determine the deployment of the relay is analyzed with the mathematical model; in addition, its performance is verified through the result of a simulation. Based on the analysis of this thesis, the established deployment and transmission power of the relay to minimize the average outage probability exist. Furthermore, the relay contributes to enlargement of capacity of cells, decreasing the average outage probability in the situation of less severe interference between cells with reuse of frequency. However, the relay should be restrained in use in the situation of severe interference between cells due to the fact that the outage probability of inter-cells can be increased.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.8C
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• pp.605-612
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• 2008

This paper researches the estimating location using repeater effect adjustment method in CDMA based system. Repeaters are commonly used by commercial and amateur radio operators to extend signals in the radio frequency range from one receiver to another. The repeater signals are increasing arrival time from base station to mobile station. So if we calculates the mobile station using repeater signals, the estimating position error is increased. However nobody researched about adjusting repeater effects. This paper proposes repeater effect adjustment algorithm. For adjusting repeater effects, we make the triangle using mobile station, reference base station and neighbor base station, and then detect the repeater effects using the triangle characteristic. The proposed method system showed the improved performance in estimating parameters and locating positions by computer simulations.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.4
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• pp.571-576
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• 2022

Due to the epochal development of the unmanned technology, the importance of LDT(: Location Detection Technology), which accurately estimates the location of a user or object, is dramatically increased. TOA(: Time of Arrival), which calculates a location by measuring the arrival time of signals, and TDOA(: Time Difference of Arrival) which calculates it by measuring the difference between two arrival times, are representative LDT methods. Based on the signals received from three or more base stations, TOA calculates an intersection point by drawing circles and TDOA calculates it by drawing hyperbolas. In order to improve the radio shadow area problem, a huge number of repeaters have been installed in the urban area, but the signals received through these repeaters may cause the serious error for estimating a location. In this paper, we propose an efficient location estimation technique using the signal received through the repeater. The proposed approach estimates the location of MS(: Mobile Station) employing TOA and TDOA methods, based on signals received from one repeater and two BS(: Base Station)s.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.10A
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• pp.746-751
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• 2009

We propose a dynamic time allocation method in cooperative multiplexing with partial relaying system. This method uses a linear programming and considers protocol that is based on relaying of partial information bits followed by cooperative multiplexing. In this protocol, regardless of the location of relay, the allocation time for each transmission time slots are constant. Using a dynamic time allocation method with considering the location of relay, we can find optimal transmission time slots, and show that the system capacity is optimized.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.445-450
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• 2020

Cooperative networks provides the benefits of performance improvements and capacity increment when the source node transmits signal to the destination node using several relay nodes. In this paper, we consider the cooperative network where the transmission scheme between the source node and relay node use conventional binary signaling, whereas the transmission scheme between thee relay node and destination node adopt the differential space time coding signaling. We analyze the performance of the system depending on the modulation scheme, i.e., coherent and differential modulation, at the source-relay links. The performance depending on the relay location is also compared by considering modulation scheme and the number of relay node.

• Journal of Korea Multimedia Society
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• v.15 no.5
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• pp.615-623
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• 2012

This paper presents T-DMB AEAS (automatic emergency alerting service) receiver model considering emergency region. The proposed receiver model determines the geographical location of the terminal by analysing the received T-DMB signal and displays the AEAS messages only if the location of terminal is similar to the emergency site. First, to determine the geographical location of the terminal, we extract the TII value from the null symbol of the SC and, based on it, calculate the location of transmitter by analysing FIG 0/22 delivering the TII-related data. The proposed algorithm sets the location of transmitter as that of receiver and displays the emergency message only in the case of the similar region. The experiment was conducted in the test environment of low power T-DMB generator based on the T-DMB AEAS messages.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.6
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• pp.1131-1136
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• 2020

Cooperative networks enhance the performance of communication systems by combining received signals from the several relay nodes where the source node transmits signals to relay nodes. In this paper, we analyze the effect of resource allocation in cooperative networks. We assume that the cooperative networks use the conventional modulation scheme between the source and relay nodes, and adopt space-time code between the relays and destination node. Both the synchronous and differential modulations are applied for the conventional scheme and differential modulation is used for the space-time code. We consider relay location and energy allocation for resource allocation, and the performance of cooperative networks depending on the number of relay is also investigated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7C
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• pp.592-600
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• 2012

In this paper, we proposed that decentralized frequency allocation scheme(DFAS) without network entry procedure between relays in mobile relay system. Frequency Indicator(FI) signal which is the reference signal of frequency division of each relay and Energy Detection(ED) region are defined. In addition, the mobile connected to the relay transmits the FI signal to neighbor relays in order to facilitate communication between relays. Finally, by using this scheme, the cell throughput improvement is confirmed.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.3
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• pp.271-276
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• 2016

Cooperative networks enhance the overall communication performance by combining signals from relay nodes and direct signal. In this paper, we analyze the performance of cooperative communication systems which use mixed relaying protocols. By assuming several relay nodes exist between the source node and destination node, we consider the systems use not a single relaying protocol but both decode-and-forward and amplify-and-forward protocols randomly. We analyze the effect of each relying protocol for the overall system performance, and also consider the performance depending on the relay location. Differential modulation scheme which demodulates signal without channel state information is adopted where it can be applicable fast varying channel such as railway environments.