  We study the problem of transmission of binary input non-linear functions
over a network of mobiles based on CDMA. Motivation for this study comes from
the application of using cheap measurement devices installed on personal
cell-phones to monitor environmental parameters such as air pollution,
temperature and noise level. Our model resembles the MAC model of Nazer and
Gastpar except that the encoders are restricted to be CDMA encoders. Unlike the
work of Nazer and Gastpar whose main attention is transmission of linear
functions, we deal with non-linear functions with binary inputs. A main
contribution of this paper is a lower bound on the computational capacity for
this problem. While in the traditional CDMA system the signature matrix of the
CDMA system preferably has independent rows, in our setup the signature matrix
of the CDMA system is viewed as the parity check matrix of a linear code,
reflecting our treatment of the interference.
