Simulation Techniques for The QAM (2D) Code

Abstract

Microcomputer-based simulation facilities, built to investigate the performance of bandwidth efficient quadrature amplitude modulation (QAM) type 2-dimensional codes, may be used to investigate the capacity of loop plants. Modulating techniques at baseband frequency are the QAM type, 2-dimensional (2-D) carrierless amplitude and phase or CAP modulation. There is no RF carrier (generally associated with QAM) per se in CAP. The CAP techniques are specifically important in the maximum utilization of available bandwidth. Data rates in copper media can thus be maximized to the full media capacity. In particular, these codes are likely to enhance the bidirectional data rates to T1 (1.544 Mbps in the United States) and to E1 (2.048 Mbps in Europe) in the subscriber loop plants. The extent and limitations are discussed in this Chapter. The feasibility of providing Basic Rate Integrated Services Digital Services (BRISDN at 144 kbps) in the various telephone environments is well documented with the 2B1Q code and is used as a benchmark (see Section 9.7.1) for the success or failure of the other more efficient modulating techniques.