Combination of speech coding and UEP coded modulation technique

• Main Authors: Chyung-Ju Wang, 王瓊珠
• Other Authors: Szu-Lin Su
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/37604565020583586034

碩士 === 國立成功大學 === 電機工程研究所 === 83 === Most of the researches on speech signal coding have put emphasis on the speech quality and the character of source coding , but seldom taked into consideration the effect of channel noise to speech signal transmission. Due to this reason , we combined source coding and channel coded modulation to obtain the better transmission performance without expanding bandwidth. We have studied several broadly accepted speech standards-- ADPCM, CELP,and American IS-96 (speech coding standard for IS -95), and learned the source coding principles and procedures. We have also studied the schemes to estimate the speech quality and selected for the proper methods that can be used in our works. We then used the simulations to find the impacts of individual source coding bit on the speech quality by controlling error bits and divide the coding bits into several groups according to their significance on the quality. The UEP coded modulation scheme is then adopted to give unequal protection capability for different bit groups. Combining such source coding and UEP coded modulation, we can achieve an improvement of communication quality.