Title   name
KSIAM 2006 Annual Meeting
  Speaker   Kim, Yoora  
  Date 2006-11-25
  Place 건국대학교
  File  의 1 번째 Real Media 동영상입니다. 의 1 번째 강연자료입니다.
Abstract : The demand for wireless communication services is tremendously increasing but available radiospectrum has a limitation. Hence the problem of maximizing spectral efficiency is one of thekey issues in wireless communication techniques. Several diversity schemes such as spatialdiversity and frequency diversity have developed to improve spectral efficiency.Recently, another form of diversity was studied, called multiuser diversity inherent in a wirelessnetwork with multiple users ( [2], [3], [7]). The strategy of multiuser diversity is similar toTDMA and assigns the channel to only one user who has the best channel condition. It is knownthat multiuser diversity is optimal channel assignment scheme in the sense of maximizing thethroughput of a multiuser system ([2], [6]).As one of the solution to the enhancement of spectral efficiency, adaptive modulation and coding(AMC) technique is used for the single user system. This technique can be applied to themultiuser system with multiuser diversity scheme since it can be treated as a single user modelunder such strategy.In this talk, we study the performance of the finite M-QAM AMC with multiuser diversitytechnique over Nakagami-m fading channel. The Nakagami-m fading model was introducedby Nakagami in the early 1940’s to characterize rapid fading in long distance HF channels ([5],p. 53). The Nakagami-m distribution is known to give the best fit to the land-mobile and theindoor-mobile multipath environment, as well as scintillating ionospheric radio links ([4], p.23). Beyond such experimental excellence, Nakagami-m fading model is universal in the sensethat it becomes the Rayleigh distribution when m = 1 and when m > 1 the Ricean fading canbe closely approximated by Nakagami-m fading model. Moreover, Nakagami-m distributioncovers no fading channel as m goes to infinity.In this talk, we show the average transmission rate and bit error rate with delayed feedbackchannel information as a closed form. Our results are general in the sense that they contain thespecial cases of the previous works ([1], [3]) in which more simple assumptions on the systemmodeling is considered.