Collision mitigation schemes for orthogonal code hopping multiplexing직교 부호 도약 다중화에서의 충돌 완화 방식에 대한 연구

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An orthogonal code hopping multiplexing (OCHM) scheme has been proposed as a novel statistical multiplexing scheme for orthogonal downlink to accommodate more low-activity bursty users than the number of orthogonal downlink codewords. However, OCHM may cause collisions or perforations among symbols, which degrade the performance of channel decoding when the perforation probability is high. Therefore, we propose several methods to mitigate the performance degradation due to the collisions or perforations in OCHM. First, we propose new log-likelihood ratio (LLR) conversion schemes inserting simple conversion functions between channel demodulator output and channel decoder input in order to improve the decoding performance in various perforation environments. Second, we disperse a collision to many symbols instead of removing a symbol by orthogonal code spreading. Third, we obtain the optimal code rate for varying the traffic load in OCHM, and propose an adaptive code rate control scheme. Finally, we lower symbol collision probability by discarding or delaying excessive frames whose number is larger than a threshold value. The above methods yield a decrease in the required $E_b/N_0$ at the transmitter and save system power.
Advisors
Sung, Dan-Keunresearcher성단근researcher
Description
한국과학기술원 : 전기및전자공학전공,
Publisher
한국과학기술원
Issue Date
2003
Identifier
231111/325007  / 000985021
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 전기및전자공학전공, 2003.8, [ vii, 100 p. ]

Keywords

Adaptive Code Rate; Orthogonal Code Pre-Spreading; Log-Likelihood Ratio; Orthogonal Code Hopping Multiplexing; Symbol Collision Probability; 심볼 충돌 확률; 적응부호화율; 직교 부호 전확산; 대수 우도비; 직교 부호 도약 다중화

URI
http://hdl.handle.net/10203/35161
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=231111&flag=dissertation
Appears in Collection
EE-Theses_Ph.D.(박사논문)
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