The Journal of Korean Institute of Communications and Information Sciences (한국통신학회논문지)

The Korean Institute of Commucations and Information Sciences (한국통신학회)
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Guard Interval Extension for Individual Users in Uplink OFDMA Mobile Communication Systems

상향링크 OFDMA 이동통신 시스템에서의 개별 사용자의 보호구간 확장

  • Published : 2007.05.31
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Abstract

While the cyclic prefix lengths of downlink OFDMA(Orthogonal Frequency Division Multiple Access) systems are determined based on the maximum delay spreads encountered in cellular environments, the guard interval of uplink OFDMA systems should consider the timing offsets of uplink signals as well as the delay spread lengths. Especially in the cases of initial accesses, handovers, and considerable time elapsed without data transmissions between base and mobile stations in a large cell, uplink timing offsets can be large and a very long guard interval length may be required. In order to keep the small size of the cyclic prefix in uplink OFDMA systems, the systems require a method of extending the guard intervals for users with large timing offsets without affecting the cyclic prefix length of the system. This paper proposes a method extending the guard intervals of individual users in uplink OFDMA systems.

하향링크 OFDMA(Orthogonal Frequency Division Multiple Access) 시스템의 경우 순환전치 구간은 지연확산만을 고려하면 되지만 상향링크 OFDMA 시스템에서는 지연확산과 함께 상향링크 신호의 타이밍 오차를 고려한 보호구간이 필요하다. 특히 셀 반경이 큰 셀에서 초기 액세스를 하는 경우, 핸드오버를 하는 경우, 오래 동안 단말이 기지국과 데이터를 주고받지 않은 경우에는 타이밍 오차가 매우 클 수 있으며 매우 큰 보호구간이 요구될 수 있다. 상향링크 OFDMA 시스템에서 작은 크기의 순환전치 구간을 유지하기 위해서는 시스템의 순환전치 구간은 그대로 둔 체 큰 타이밍 오차가 발생할 수 있는 단말의 보호구간만 증대시키는 방법이 필요하다. 이 논문에서는 상항링크 OFDMA 시스템의 보호구간을 사용자 개별적으로 확장하는 방법을 제안한다.

Keywords

References

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