Implementing Cooperative Diversity by Using LDPC Code and Space-Time Code

Spatial diversity is an effective method to resist fading effect in wireless channel. Due to the limitation of size, weight and cost, it is difficult to use the multi-antenna technique on the terminal of wireless communication. Cooperative communication allows the sharing of antennas among the single antenna mobile terminals to create a virtual multi-antenna, which further leads to the realization of transmitting diversity. Because of the coherence among the symbols of the LDPC code word, we can create a virtual MIMO system and obtain diversity gain by making space-time coding in the part of the symbols and transmitting them via different users´ antennas. Once diversity gain is obtained, the system performance can be improved effectively, without any rise in the system bandwidth and transmitting power.