Bao, the functions you mentioned -- symbol mapper, etc. -- are usually integrated in a single IC, not sold as separate components.
Most of the modem functions can be implemented digitally on an FPGA, or better yet, one FPGA for the transmitter and another one for the receiver. If you focus on the system design & digital implementation, you should discover that the only other components you need besides the FPGAs are A/D and D/A converters and amplifers.
I am Bao, a student at California State University, Long Beach. This is my project requirements:
Design a digital communication system capable to transmit digital signal using both QPSK and 16QAM signaling schemes. Data rate about 100 kbps. Input signal to transmitter is human voice, and output signal will be stored in the receiver and then played out from a speaker. Channels will be both wire and wireless. I need help in finding ICs for my project (symbol mapper, quadrature modulators, quadrature oscillators, …)