Performance analysis of ADSL modems under the crosstalk noise from ISDN and a study of performance improvement,
- K. Matsumoto, H. Nakagawa, M. Ueda
- Tech. Report of IEICE,
Asymmetric Digital Subscriber Line (ADSL) is a transmission system capable of realizing rates from 1.5Mbps to 9Mbps over existing telephone lines. In Japanese subscriber lines, however, the data rate performance of ADSL decreases severely when adjacent time compression multiplexing ISDN (TCM-ISDN) lines cause crosstalk noise to ADSL line. We propose using repetition scheme for ADSL system to improve the data rate performance. The transmission of ADSL is synchronized with TCM-ISDN burst, and the repetition scheme is employed only in the Nearend Crosstalk (NEXT) period. We theoretically analyze the performance of the systems with single number of repetition times for all the subchannels, and with adaptive number of repetition times for each subchannel respectively. It is found that the data rate performance of the proposed system is higher than that of the conventional single data rate system.