Improved Cooperative Diversity Schemes Based on Superposition Modulation Strategies

In wireless sensor network, cooperative diversity is a very important technology, which enables users to share their antennas by using of the redundant node properties to improve space transmit diversity, also provide resistance to increase the output and channel fading effects. But how to transmit cooperatively during nodes in the wireless sensor network especially the receiving terminal node how to decode to reach a higher efficient data transmission are still some further considerable questions. The paper introduces a superposition modulation strategy based on traditional transmission schemes. By using of this strategy , firstly designs a new symbol mapping method based on the nodes’ link states and power allocation, secondly discusses the receiving terminal node’s decode problems about the signal-to-noise and bit error probability. This optimize arithmetic does not only solve one half of slot in use of the traditional cooperative mode by comparing with the no-cooperative mode and the decode-forward cooperative mode, but also decreases the bit error probability on performance. In addition, the paper proves that this new method could improve three dB of signal-to-noise at most than the traditional transmission mode. The simulation result shows that well link state with suitable power allocation not only transmits their and partners’ data at the same time, but also balances system performances.