On the Capacity of Quantized Gaussian MAC Channels With Finite Input Alphabet

In this paper, the authors investigate the achievable rate region of Gaussian Multiple Access Channels (MAC) with finite input alphabet and quantized output. With finite input alphabet and an unquantized receiver, the two-user Gaussian MAC rate region was studied. In most high throughput communication systems based on digital signal processing, the analog received signal is quantized using a low precision quantizer. In this paper, they first derive the expressions for the achievable rate region of a two-user Gaussian MAC with finite input alphabet and quantized output. They show that, with finite input alphabet, the achievable rate region with the commonly used uniform receiver quantizer has a significant loss in the rate region compared.