• Title/Summary/Keyword: WCDMA

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Speech Packet Transmission Using the AMR-WB Coder with FEC (FEC기능을 추가한 AMR-WB 음성 부호화기를 이용한 음성 패킷 전송)

  • 황정준;이인성
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.40 no.11
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    • pp.63-71
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    • 2003
  • This paper suggests the packet loss recovery method to communicate in real time in the Internet. To reduce the effects of packet loss, Forward Error Correction (FEC) that adds redundant information to voice packets can be used. Adaptive Multi Rate Wideband(AMR-WB) codec which is recently selected by the Third Generation Partnership Project(3GPP) for GSM and the third generation mobile communication WCDMA system and has also been standardized in ITU-T for providing wideband speech services is used. The major cause for speech qualitly degradation in IP-networks is packet loss. So, We recovered single lossy packet by using FEC method and concealed continued errors. The proposed scheme if evaluated in the Gilbert Internet channel model. The high quality of audio maintained up to 30% packet loss.

A Study on Adaptive Interference Canceller of Wireless Repeater for Wideband Code Division Multiple Access System (WCDMA시스템 무선 중계기의 적응간섭제거기에 관한 연구)

  • Han, Yong-Sik;Yang, Woon-Geun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.7
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    • pp.1321-1327
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    • 2009
  • In this paper, as the mobile communication service is widely used and the demand for wireless repeaters is rapidly increasing because of the easiness of extending service areas. But a wireless repeater has a problem the oscillation due to feedback signal. We proposed a new hybrid interference canceller using the adaptive filter with CMA(Constant Modulus Algorithm)-Grouped LMS(Least Mean Square) algorithm in the adaptive interference canceller. The proposed interference canceller has better channel adaptive performance and a lower MSE(Mean Square Error) than conventional structure because it uses the cancellation method of Grouped LMS algorithm. The proposed detector uses the LMS algorithms with two different step size to reduce mean square error and to obtain fast convergence. This structure reduces the number of iterations for the same MSE performance and hardware complexity compared to conventional nonlinear interference canceller.

Research for Application of Interactive Data Broadcasting Service in DMB (DMB에서의 양방향 데어터방송 서비스도입에 관한 연구)

  • Kim, Jong-Geun;Choe, Seong-Jin;Lee, Seon-Hui
    • Broadcasting and Media Magazine
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    • v.11 no.4
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    • pp.104-117
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    • 2006
  • In this Paper, we analyze the application of Interactive Data Broadcasting in DMB(Digital Multimedia Broadcasting) in the accordance with convergence of service and technology. With the acceleration of digital convergence in the Ubiquitous period substantial development of digital media technology and convergence of broadcasting and telecommunication industry are being witnessed. Consequently these results gave rise to newly combined-products such as DMB(Digital Multimedia Broadcasting), WCDMA(Wide-band code division multiple access), Wibro(Wireless Broadband Internet), IP-TV (Internet protocol TV) and HSDPA(High speed downlink packet access). The preparatory stage for the implementation of Interactive Data Broadcasting Service will be reached by the end of December, 2006. DMB is the first result of a successful convergence service between Broadcasting and Telecommunication in new media era. Multimedia technology and services are the core elements of DMB. The Data Broadcasting will not only offer various services of interactive information such News, Weather, Broadcasting Program etc, but also be linked with characteristic function of mobile phone such as calling and SMS(Short Message Service) via Return Channel.

Size Reduction of a Quasi Class-E High Power Amplifier Using Defected Ground Structure (결함 접지 구조를 이용한 유사 E급 전력 증폭기의 소형화)

  • Choi, Heung-Jae;Jeong, Yong-Chae;Lim, Jong-Sik;Jung, Young-Bae;Eom, Soon-Young;Kim, Chul-Dong
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.1
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    • pp.61-68
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    • 2010
  • In this work, a reduced size 20W quasi class-E Power Amplifier(PA) with defected ground structure load-network is presented for WCDMA base station application. Harmonic impedances required for the class E operation are satisfied by applying the dumbbell and the asymmetric spiral DGS. Open impedance for 2nd harmonic frequency which has the highest power and nearly short impedances for other higher order harmonics are provided by the proposed DGS load-network. The maximum Power Added Efficiency(PAE) of 70.2 % at the output power of 43.1 dBm with the saturated power gain of 12.7 dB is achieved by the proposed quasi class-E PA, which is comparable to the performance of the reference class-E PA. Total size of the proposed class-E PA is only $50{\times}50\;mm^2$ and much smaller than the conventional class-E PA that is loaded with a number of open stubs.

Dual-Band Array Antenna Using Modified Sierpinski Fractal Structure (변형된 Sierpinski 프랙탈 구조를 갖는 이중 대역 배열 안테나)

  • Oh, Kyung-hyun;Kim, Byoung-chul;Cheong, Chi-hyun;Kim, Kun-woo;Lee, Duk-young;Choo, Ho-sung;Park, Ik-mo
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.21 no.9
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    • pp.921-932
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    • 2010
  • This paper presents a dual-band array antenna based on a modified Sierpinski fractal structure. Array structure is mirror symmetric, and forms broadside radiation pattern for dual frequency band if the ports are fed with $180^{\circ}C$ phase difference between upper and lower $2{\times}1$ array. To use in-phase corporate feeding circuit, the phase inversion structure is designed by changing the position of patch and ground for upper and lower array. The dimensions of the array antenna is $28{\times}30{\times}5\;cm^3$ and the bandwidth of 855~1,380 MHz(47 %), 1,770~2,330 MHz(27 %) were achieved for -10 dB return loss. The measured gain is 9.06~12.44 dBi for the first band and 11.76~14.84 dBi for the second band. The half power beam width is $57^{\circ}$ for x-z plane and $46^{\circ}$ for y-z plane at 1,100 MHz and $43^{\circ}$ and $28^{\circ}$ at 2,050 MHz, respectively.

The basic experiments for the fabrication of the SPUDT type Inter using the SFIT type filter (SFIT형태를 이용한 SPUDT형 필터제작에 관한 기초실험)

  • You, Il-Hyun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.10
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    • pp.1916-1923
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    • 2007
  • We have studied to obtain the SAW filter for the passband was formed on the Langasite substrate and was evaporated by Aluminum-Copper alloy and thin we performed computer-simulated by simulator. We cm fabricate that the block weighted type IDT as an input transducer of the filter and the withdrawal weighted type IDT as an output transducer of the filter from the results of our computer-simulation. Also, we have performed to obtain the properly design conditions about phase shift of the SAW filter for WCDMA. We have employed that the number of pairs of the input and output IDT are 50 pairs and the thickness and the width of reflector are $5000\;{\AA}$ and $3.6{\mu}m$ respectively. And we have employed that the distances from the hot electrode to the reflector are $2.0{\mu}m$, $2.4{\mu}m$ and the distance from the hot electrode to the ground is $1.5{\mu}m$ respectively. Frequency response of the fabricated SAW filter has the property that the center frequency is about 190MHz and bandwidth at the 3dB is probably 7,8MHz. And we could obtain that return loss is less then -18dB, ripple characteristics is probably 3dB and triple transit echo is less then -25dB after when we have matched impedance.