• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.05a
• /
• pp.43-46
• /
• 2015

Recently, full-duplex communications has been considered as one of the most promising techniques for net-generation mobile communication system. In this paper, we propose a compressed sensing based signal detection technique for full-duplex generalized spatial modulation (FD-GSM) systems. In FD-GSM systems, some antennas are used for signal transmission according to input data and the otehrs are used for detecting signals received over the same frequency band. The self-interference (SI) is assumed to be completely removed by help for the recently proposed SI cancellation techniques. The proposed signal detection technique significantly outperforms the conventional ones in terms of symbol error rate (SER). We will investigate the optimal number of used antennas in FD-GSM systems.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.45 no.1
• /
• pp.78-84
• /
• 2008

In this paper, the reconfigurable annular ring slot antenna with circular polarization diversity is proposed for SDMB(Satellite Digital Multimedia Broadcasting) system. The proposed antenna consists of a ring slot with four tuning stubs. Four PIN diodes are attached to switch circular polarization diversity. By switching the diodes ON or OFF, the proposed antenna can be operated either RHCP mode or LHCP mode. The experimental result shows that the proposed antenna has an impedance bandwidth(VSWR${\leq}$2) of 570MHz(2.47-3.04GHz) at LHCP mode, an impedance bandwidth (VSWR${\leq}$2) of 560MHz(2.45-3.01GHz) at RHCP mode, a maximum gai of 3.1dBi at RHCP mode, 4.76dBi at LHCP mode. The 3dB CP bandwidth of about 100MHz at both RHCP and LHCP mode is achieved at the center frequency 2.63GHz. The proposed antenna is suitable for application such as mobile satellite communications, WLAN(Wireless Local Area Networks), and broadband wireless communication systems.

• Journal of IKEEE
• /
• v.12 no.1
• /
• pp.1-7
• /
• 2008

With the recent development of portable system such as mobile communication and multimedia. Full adders are important components in applications such as digital signal processors and microprocessors. Thus It is important to improve the power dissipation and operating speed for designing a full adder. We propose a new adder with modified version of conventional Ratioed logic and Pass Transistor logic. The proposed adder has the advantages over the conventional CMOS, TGA, 14T logic. The delay time is improved by 13% comparing to the average value and PDP(Power Delay Product) is improved by 9% comparing to the average value. Layouts have been carried out using a 0.18um CMOS design rule for evaluation purposes. The physical design has been evaluated using HSPICE.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.36D no.4
• /
• pp.1-7
• /
• 1999

The demands for the various type of directional coupler, which is for the sampling of the signal levels in mobile communication baseband or transceiver systems, are growing. The proposed dual directional coupler, which has three parallel coupled transmission lines, can provide the dual coupling and good isolation characteristics between the coupling ports. In this paper, the novel analysis method and the design equation of even and odd mode for the dual directional coupler, which is employing the asymmetrically coupled transmission lines, are proposed. Using the proposed method, the dual directional coupler for PCS system has been designed and fabricated. We obtained the desired coupling value and the high directivity of 40dB. Measured results show the validity of this design method.

• Spatial Information Research
• /
• v.18 no.4
• /
• pp.75-88
• /
• 2010

Recent development in wireless communication and mobile positioning technologies make geosensor networks widely used in the various fields of real world. As a result, much research has been done on the middleware that uses limited energy resources efficiently. However, because traditional middleware does not consider the characteristics of sensor node, such as computing power and specification, the existing middleware call not support the sensor nodes with only the restricted system resource. Therefore, in this paper, we design and implement a new Bytecode based Data Service Middleware supporting energy efficiency in geosensor networks. At first, the proposed middleware provides the optimized functions for sensor nodes by using minimum by tee ode instruction set and data manager supporting hardware abstraction. Secondly, the proposed middleware increases the energy efficiency of sensor node through both data aggregation query processing and data filtering that minimize data transmission by eliminating unnecessary data. Finally, we show from our performance analysis that the proposed middleware is more energy efficient than the existing SwissQM.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.43 no.3 s.345
• /
• pp.103-110
• /
• 2006

Turbo code, a kind of error correction coding technique, has been used in the field of digital mobile communication system. As the number of iterations increases, it can achieves remarkable BER performance over AWGN channel environment. However, if the number of iterations Is increases in the several channel environments, any further iteration results in very little improvement, and requires much delay and computation in proportion to the number of iterations. To solve this problems, it is necessary to device an efficient criterion to stop the iteration process and prevent unnecessary delay and computation. In this paper, it proposes an efficient and simple criterion for stopping the iteration process in turbo decoding. By using variance values of noise derived from mean values of LLR in turbo decoder, the proposed algorithm can largely reduce the computation and average number of iterations without BER performance degradation. As a result of simulations, the computation of the proposed algorithm is reduced by about $66{\sim}80%$ compared to conventional algorithm. The average number of iterations is reduced by about $13.99%{\sim}15.74%$ compared to CE algorithm and about $17.88%{\sim}18.59%$ compared to SCR algorithm.

• Journal of the Korean Institute of Telematics and Electronics C
• /
• v.36C no.1
• /
• pp.1-11
• /
• 1999

In this paper, we proposed a design method of parameterized viterbi decoder, which automatically synthsizes the diverse viterbi deciders used in the digital mobile communication systems. It is designed to synthesize a viterbi decoder specified by user-provided parameters. Those parameters are constraint length, code rate generator polynomials of teh convolutional encoder, data rate and bits/frame of the data transmission, and soft decision bits of viterbi decoder. For the design of the parameterized viterbi decoder, we designed a user interface module C-language, and a viterbi decoder module in a hierarchical atructure using VHDL language and its generic statement. For the verification of the parameterized viterbi decoder, we compared our synthesized viterbi decoder with the conventional viterbi decoder which is designed for the IS-95 CDMA system. The proposed design method of the viterbi decoder will be a new method to obtain a required viterbi decoder in a very short time only by supplying the design parameters.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.48 no.9
• /
• pp.1-9
• /
• 2011

In this paper, we propose an efficient method to create clusters of geographically distributed base stations which cooperatively transmit signals in cellular mobile communication systems. The proposed method utilizes a sequential selection approach to choose candidate base stations which can provide maximum weighted sum-rate gain when they participate in the cooperative transmission with the existing cluster. In particular, the proposed method limits the maximum number of base stations in a cluster by considering the system operational and implementation complexities. Moreover, the combinations of clusters dynamically change along with variations of channel environments. Through computer simulations, performance of the proposed method is verified by comparing with the non-cooperative transmission method and the static clustering method. Numerical result shows that the proposed sequential selection based clustering method is especially advantageous for the performance improvement of lower percentile users in terms of average throughput, and thus the proposed method can effectively improve the fairness among users.

• Journal of the Korea Society for Simulation
• /
• v.17 no.3
• /
• pp.1-8
• /
• 2008

It is essential to maintain constant QoS despite of cell overload or erroneous wireless link during transmission because QoS of a multimedia service may be severely degraded by small delay or packet loss. This paper deals with a cell selection method for supporting the QoS of multimedia services over heterogeneous networks. The proposed scheme is based on Fuzzy Multi-Criteria Decision Making (FMCDM), in which uncertain parameters such as user system preference, the communication cost and cell load, and the transmission delay are used in the decision process using the aggregation function in fuzzy set theory. In this scheme, errors in the evaluation parameters impose milder changes on the total evaluation value than in binary logics. Simulation is focused on the average delay and packet loss rate, and the simulation results show that our proposed method provides mobile terminals the optimal performance.

• Journal of Advanced Navigation Technology
• /
• v.21 no.5
• /
• pp.428-434
• /
• 2017

In recent years, owing to the growing user demand for the two-way internet service based on the mobile global broadband communications, a new type of satellite terminal has been developed, known as ESIM(Earth Station in Motion). This service was required by Resolution 158(WRC-15) to study on the coexistence with the co-primary FS(Fixed Service) in 27.5-29.5 GHz as a FSS(Fixed Satellite Service) uplink. In this paper, the average received power on ESIM within -10 dB of beam width of FS and its outage probability was analyzed theoretically and also simulated to account for the azimuth angle with uniform distribution. From the results, it can be concluded that this theoretical analysis is very useful to analyze the interference from ESIM into FS based on the statistical and probabilistic method. Therefore, it is necessary to control the azimuth angle due to a moving terminal as well as the inclination angle of moving path, the operation hours, and the speed of ESIM to protect the co-primary FS.