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The performance of the Reed Solomon coder/decoder for an ADSL modem is studied. The proposal incorporates a new faster parallel structure for the RS coding/decoding part of the modem that exploits the single latency operation of the device. The modem is fully compatible with the existing standard of T1E1.4 ANSI Standard Group and ADSL Forum requirements. The proposed structure was simulated and the results confirmed significant savings. Only the coding/decoding part of the modem was simulated. The simulation results of the parallel structure showed approximately 50% improvement in the speed of the RS coding/decoding operation. The correcting possibilities of the RS code were also confirmed and shown in the simulation results. The paper is organized as follows. The specific structure of the modem is presented. A brief introduction to Reed Solomon codes for ADSL applications is then given. Finally, the simulation results are presented.

In this paper we present the simulation results of a concatenated Reed Solomon-convolutional encoder scheme. The structure proposed was designed with the purpose of being used in ADSL applications. RS (255,239) is used as the outer code, which is proposed by the ANSI T1E1.4 Standard Group. The role of the inner code is undertaken by a convolutional encoder, which protects the outer one from random errors, while the RS code is responsible for the correction of burst errors. The noise model used, AWGN, is generally accepted as the worst case for ADSL transmission. A burst impulsive noise was also simulated proving the correcting capabilities of the RS code. The paper is organized as follows: After the introduction, a description of the simulated system is given. Next, the simulation method is described. The results from the simulation are represented, and, finally, the conclusions and some proposals for the improvement of the system are given.